Automotive
hamzasoapz
14-Learnersguide-AURETR006-Solderelectricalwiringandcircuits-converted1.pdf
Solder electrical wiring
and circuits
AURETR006
Solder electrical wiring and circuits
ii
Application
This unit describes the performance outcomes required to solder electrical
components, electrical circuits and system wiring. It involves preparing for the task,
preparing components, circuits and wiring for soldering, carrying out soldering, and
completing workplace processes and documentation.
It applies to those working in the automotive service and repair industry. The
electrical wiring and circuits include those in agricultural machinery, heavy
commercial vehicles, light vehicles, vessels, mobile plant machinery, motorcycles
or outdoor power equipment.
No licensing, legislative, regulatory or certification requirements apply to this unit at
the time of publication.
Pre-requisite Unit
NIL
Competency Field
Electrical
Unit Sector
Technical - Electrical and Electronic
Solder electrical wiring and circuits
iii
Elements and Performance Criteria
ELEMENTS
(Describe the
essential
outcomes)
PERFORMANCE CRITERIA
(Performance criteria describe the performance
needed to demonstrate achievement of the
element)
MAPPING
INFORMATION
1. Prepare to
solder
electrical
wiring and
circuits
1.1. Job requirements are determined according to
workplace instructions.
Page 18 - 25
1.2. Technical procedures and information are
accessed and interpreted.
Page 18 - 21
1.3. Hazards associated with the work are identified
and risks are managed
Page 2, 3
1.4. Tools, equipment and materials are selected
and checked for serviceability.
Page 21 - 24
2. Prepare
components,
circuits and
wiring for
soldering.
2.1. Materials and components to be joined are
selected and prepared according to workplace
procedures and safety and environmental
requirements.
Page 27
2.2. Solder and flux type are identified and prepared. Page 31- 33
2.3. Soldering equipment is cleaned and prepared
ready for use.
Page 38
3. Carry out
soldering of
components,
circuits and
wiring.
3.1. Soldering is carried out according to workplace
quality expectations, and without causing
damage to vehicle, components, electrical
circuits and system wiring
Page 40 - 42
3.2. Soldered connection is inspected visually and
checked to ensure effectiveness.
Page 40 - 42
4. Complete
work
processes.
4.1. Final inspection is made to ensure work is to
workplace expectations and vehicle, vessel or
machinery is presented ready for use.
Page 43, 44
4.2. Work area is cleaned, waste and non-recyclable
materials are disposed of, and recyclable
material is collected.
Page 45
Solder electrical wiring and circuits
iv
4.3. Tools and equipment are checked and stored
and any faulty electrical equipment is identified,
tagged and isolated according to workplace
procedures
Page 45
4.4. Workplace documentation is processed
according to workplace procedures
Page 46 - 49
Solder electrical wiring and circuits
v
Knowledge Evidence
KNOWLEDGE OUTCOMES MAPPING
INFORMATION
• Work health and safety (WHS) and occupational health
and safety (OHS) requirements relating to soldering
electrical wiring and circuits, including procedures for:
o using safety data sheets (SDS) on page 20
o selecting and using personal protective equipment
(PPE)
Page 3,4
o safely handling materials during solder process Page 5,6
o safely operating soldering equipment Page 6 - 8
o identifying and using firefighting and first aid equipment Page 9 -16
• Environmental requirements, including procedures for
trapping, storing and disposing of material released during
soldering process
Page 16,17
• Location and content of workplace preparation and
soldering procedures, SDS and manufacturer specifications
Page 20
• Procedures for preparing to solder electrical wiring and
circuits, including:
o preparing and cleaning components to be soldered,
including selecting appropriate cleaning solutions
Page 36 - 40
o methods of holding components to be soldered Page 39
o soldering fluxes and their application Page 31 - 33
o resin core solder types, diameter and application Page 33
o types and applications of soldering irons Page 27,28
• Procedures for soldering electrical wiring and circuits,
including:
o applying heat and solder to the parts to be joined Page 40 - 42
Solder electrical wiring and circuits
vi
o allowing cooling without movement Page 40 -42
• Work completion procedures for soldering electrical wiring
and circuits, including procedures for final visual inspection
of soldered connections, including:
o manufacturer and workplace specifications for
acceptable soldering standard
Page 45
o post-soldering insulation, including heat shrink sleeving
and application of electrical tape.
Page 44
Solder electrical wiring and circuits
vii
Table of Contents
1 Introduction ................................................................................................. 1
2 Hazards and safety .................................................................................... 2
2.1 Work health safety (WHS) .................................................................................... 2
2.2 Hazards while working on the soldering ............................................................. 2
2.3 Safety ..................................................................................................................... 3
2.3.1 Safely handling materials during the soldering process .......................................... 5
2.3.2 Soldering safety ............................................................................................................ 6
2.3.3 Safety precautions for soldering ................................................................................. 8
2.3.4 Fire safety ...................................................................................................................... 9
2.4 First aid ................................................................................................................. 16
2.5 Environmental requirements .............................................................................. 16
3 Planning and preparation ....................................................................... 18
3.1 Service information ............................................................................................ 18
3.2 Workplace preparation ..................................................................................... 20
3.3 Safety data sheets.............................................................................................. 20
3.4 Tools and equipment ......................................................................................... 22
3.4.1 Soldering iron .............................................................................................................. 22
4 Soldering .................................................................................................... 26
4.1 Operation of soldering ....................................................................................... 27
4.2 Heat application method of soldering ............................................................. 28
4.2.1 Resistance soldering .................................................................................................. 28
4.2.2 Torch Soldering ........................................................................................................... 29
4.2.3 Dip Soldering ............................................................................................................... 30
4.3 Soldering flux ....................................................................................................... 30
4.3.1 Types of flux ................................................................................................................. 31
5 Soldering electrical wiring and circuits................................................... 34
5.1 Soldering iron tip selection ................................................................................. 34
5.2 Component removal tip selection .................................................................... 35
5.2.1 Vacuum desoldering tip selection ........................................................................... 35
5.2.2 Hot air tool tip selection ............................................................................................. 35
5.2.3 Conductive tool tip selection ................................................................................... 35
Solder electrical wiring and circuits
viii
5.3 Preparing for the soldering ................................................................................ 36
5.4 Cleaning and preparation ................................................................................ 36
5.4.1 Plated through hole preparation ............................................................................. 38
5.4.2 Surface mount pad preparation .............................................................................. 39
5.5 Soldering operation ............................................................................................ 40
5.5.1 Soldering wires/ electrical connections .................................................................. 41
5.5.2 Desoldering ................................................................................................................. 42
5.5.3 Fixing mistakes............................................................................................................. 42
6 Work completion procedures and documentation ............................. 43
6.1 Final visual inspection of soldered connections .............................................. 43
6.2 Post-soldering insulation ..................................................................................... 44
6.3 Types of sleeves and sleeving ........................................................................... 44
6.4 Workshop procedures ........................................................................................ 45
6.5 Documentation .................................................................................................. 46
7 References ................................................................................................ 50
Solder electrical wiring and circuits
1
1 Introduction
While repairing complicated wiring system, joining the wires or joining the electronic
components is important. Hence, soldered connections are used in the repair of
electrical wiring to form a continuous and permanent metallic connection having a
constant electrical value. The importance of creating and maintaining a high
standard of work for soldering operations is used in the automotive wiring repair.
Figure 1: Soldering electrical circuits
This unit describes the materials and equipment used in soldering, interconnecting
wiring and components. It also describes and illustrates the preparation and care of
equipment, procedures to be followed, and the soldering techniques necessary to
make a good soldered joint.
Solder electrical wiring and circuits
2
2 Hazards and safety
2.1 Work health safety (WHS)
Figure 2: Work health and safety
Work health and safety (WHS) govern the safety, health and well-being of people
involved in work or employment. Irrespective of the nature of work, employees must
be able to carry out their responsibilities in a safe and secure work environment
which is free from hazards.
The objectives of WHS are to:
• Ensure health, safety and welfare of employees and other people at work;
• Protect the public from the health and safety risks of business activities;
• Eliminate workplace risks at the source; and
• Involve employers, employees and the organisations that represent them in the
formulation and implementation of health, safety and welfare standards.
NOTE: “The employer must not expose technicians to substances that are hazardous
to health” and “should constantly monitor the process and exhaust gases, fumes
and particulate levels.”
2.2 Hazards while working on the soldering
While working on the soldering electrical wiring and circuits, the technician must be
aware of possible hazards and safety measures associated with them. Here are
some of the possible hazards while working on the soldering electrical circuits and
wiring:
Solder electrical wiring and circuits
3
• Toxic materials: Solder is performed using the lead as the flux. Lead is considered
hazardous which contaminates the skin and enters the human body either
directly through inhalation or indirectly transferred by hand while having food.
Figure 3: Fumes generated during soldering
Solder fume, also known as colophony, is a complex fume containing particles
and gases that are hazardous to health if inhaled.
• Heat: Soldering iron tip will produce high amount of heat which can cause burns.
Any miss handling of the molten solder can come in contact with the eyes or skin
and is dangerous.
• Fire: The heat generated by the soldering iron is enough to start a fire.
• Electrical Hazards: Electric soldering irons lead to electrical hazards like shocks
and burns.
• Spattering: Solder and flux can spit or spatter when heated.
Hazards identification and risk assessment:
Hazard identification is an important step in the safety management process. This
helps in identifying and assessing every hazard related to work and to control or find
the solution at the earliest. Hazard control is an active program of preventing the risk.
While performing a task the technician should assess the possible hazards and risks in
the task and should understand the severity of the hazard to take the necessary
action.
2.3 Safety
While soldering electrical wiring and circuits, individual will be working with the high
temperature equipments and components. Soldering material flux and fumes are
harmful for the individual when it comes in contact with the human skin, hence the
Solder electrical wiring and circuits
4
safety practices has to be followed while working on the soldering operation.
In the automobile service, it is very important to follow the safety practices as we
work with many hazards, some are expected, and some are not. So, one working on
the diagnosis of vehicle should be capable of risk assessment and risk management.
Figure 4: Personal protective equipment
Personal protective equipment (PPE) is designed to protect from specific hazards
and hazardous materials. It is the final protection system to be used and it does not
reduce or eliminate the hazard but only protects the person wearing it.
• Protective Clothing (sleeves) – To prevent from splashes and hot solders
• Face masks – To prevent from toxic lead fumes of solders
• Eye protection (Goggles) – To prevent from sudden splashes
Selecting and using personal protective equipment (PPE):
✓ Eye and Face protection – The equipment must fit properly and be comfortable to
wear. Face masks are used to prevent from toxic lead fumes of solders. Eye
protection (Goggles) are used to prevent from sudden splashes. A technician
should wear all the time in order to protect the eyes from any spillages and this
should meet OSHA standard.
Example – Safety glasses, face shields, chemical splash goggles
✓ Respiratory protective equipment – It prevents from inhaling hazardous chemicals,
asbestos, fumes, brake dust etc.
Example – Air-purifying respirators, supplied air respirator.
Solder electrical wiring and circuits
5
✓ Hearing protective devices – These devices help in noise reduction and provide
comfort while working on noisy machinery.
Example – Earmuffs, hearing bands, ear plugs
✓ Head protection – It is important to wear head protection to prevent any impacts
and penetration of hazards while working under the vehicle.
Example – Hard hats, safety helmets.
✓ Skin protection – Hazards like absorption of harmful substances, chemical or
thermal burns, electrical dangers, bruises, cuts, and fractures can be prevented
by wearing skin protection PPE.
Example – Safety gloves, heat resistance gloves, metal or leather mesh gloves.
✓ Protective clothing – Protective Clothing (sleeves) are work to prevent from
splashes and hot solders. Various protective clothing is available to avoid hazards.
These provide protection against heat, chemical spills and fire sparks.
Example – Uniforms, Overalls.
✓ Foot protection – Foot and leg injuries are caused by slippery surfaces, electrical
hazards, penetrating materials, falling and hot substances. These are prevented
by wearing foot protection.
Example – Safety boots, rubber boots.
Visit PPE for additional information.
2.3.1 Safely handling materials during the soldering process
Solder spillage must be collected and removed using a thick cloth promptly to
prevent air contamination by lead material.
Discard lead solder in an approved container with a lid. The collection container
should be labelled with an approved hazardous waste label.
This must be disposed as per EPA regulations and do not throw them in trash cans.
Control of solder fumes
• Fume extraction should be through an enclosed hood or tip extraction.
• Use the filter boxes with the activated carbon and HEPA filter to extract the fumes.
• Use benchtop filter extract systems
• Rosin-free soldering in well-ventilated areas
Solder electrical wiring and circuits
6
Figure 4: Safe breathing equipment
• All extract systems should be tested at least annually and maintained. Keep a log
of filter changes or mark date on filter/system.
• Do not solder if the extract is not working properly and report immediately.
Handling solder, flux and cleaners
• Solder can spill. Hence, wear eye protection.
• Use rosin-free and lead-free solders wherever possible.
• Keep cleaning solvents in dispensing bottles.
• Always wash hands with soap after soldering.
• As lead can lead to serious long-lasting health effects. Resist the exposure through
accidental absorption from skin, by wearing gloves while handling solder.
• The rosin can cause eye, throat and lung irritation, nose bleeds and headaches
when exposed. Hence, take the necessary respiratory precautions while working
on the rosin flux.
2.3.2 Soldering safety
Safely handling soldering iron:
• Do not touch the tip of soldering iron.
• Always keep the soldering iron to its stand when not in use.
• Turn off the solder when not in use
• Wear Personal protective equipment like goggles, face masks
• Make sure that the working surface in non-flammable
Solder electrical wiring and circuits
7
• Check for availability of fire extinguishers and first aid kits in the workplace
• Conduct soldering in well ventilated workplace
Soldering safety also includes the following:
• Never put activated soldering iron on the work area unattended.
• Do not use soldering iron tip to press or force anything, as this could result in a
sudden forceful release of force causing molten solder to fly off the iron tip.
• The soldering iron is plugin electrical device and must have a current safety test
tag.
• Before use, the technician should visually check that the soldering iron does not
have damage such as melted insulation on the lead, broken or cracked handle
or exposed conductors.
• Don’t use damaged equipment and report the damage.
• For electrical safety, the exposed metal parts such as the tip and heating element
are earthed.
• Don’t solder on any working equipment as contact with the earthed tip may
cause damage to the equipment or soldering iron.
Figure 5: Safe handling of soldering iron
Electrical Safety
• Do not use damaged soldering to body, cable or plug.
• Ensure all soldering irons should have had electrical safety testing within the
required time.
• Make sure to keep the soldering station free of electrical cables to prevent
damage from the heated tip.
Solder electrical wiring and circuits
8
• Use a grounded outlet and grounding prong if a short circuit is a possibility.
2.3.3 Safety precautions for soldering
Before starting
• Inspect for the general work area to ensure no slip/trip hazards are present.
• Ensure the bench top work area is clear.
• Inspect the power lead and soldering iron for obvious damage, including tip
damage.
• Make sure enough ventilation is provided.
Dos and don’ts
• Always leave the soldering iron in the stand when it is warming up.
• Place the soldering iron back in the stand immediately following each use.
• Do not position the head directly over the soldering process.
• Do not breathe solder flux fumes.
• Avoid the contact of the isopropanol solution on skin or objects when cleaning
circuit boards.
• Ensure the board is covered with a lint-free wipe to absorb dissolved resin flux and
minimise isopropanol spills.
• Do not use faulty equipment and report immediately to the supervisor.
• Do not misuse a soldering iron for anything other than soldering electronic
components.
• Avoid touching the soldering iron tip to an electrical cord.
• Do not tap the soldering iron to remove excess solder.
• Do not leave the soldering iron switched on when not in use – this will oxidise the
tip and reduces tip life.
• Never purposefully inhale or drink isopropanol.
Ending the operation and cleaning:
• Make sure the soldering iron tip is well tinned before switching off the soldering
iron.
Solder electrical wiring and circuits
9
• Switch off, unplug and allow the soldering iron to cool down before storing.
• Return unused isopropanol to an approved storage container using a funnel.
• Make sure workbench is the safe, clean and tidy state.
Fire Prevention
• Work on a fire-proof or fire-resistant surface.
• Wear fire-resistant clothing that covers arms and legs to prevent accidental burns.
• Know the location of nearest fire extinguisher and how to use it.
• Soldering should never occur in the immediate vicinity of flammable gases or
liquids.
• Soldering shall only be performed in areas that are free of combustible materials
including trash, wood, paper, textiles, chemicals, flammable dust, liquids and
gases.
• Fire extinguishers must be placed in surrounding work area.
2.3.4 Fire safety
Fire is the most common hazard that creates huge destruction in the workplace. It
results in serious injuries and is dangerous to human life.
WHS for identifying and using firefighting and first aid equipment
• Check for availability and location of fire extinguisher in the workplace.
• Be aware of the emergency evacuation procedure and exit and assembly points
in the workplace.
• Be aware of general emergency contact numbers such as fire service,
Ambulance and police.
• Be aware of the first aid kit location in the workplace
• Seek assistance, professional medical aid immediately in case of burns or physical
injuries.
There are four types of fire that may occur in a workshop.
• Class A fire – These are caused by ordinary combustibles such as wood, cloth,
paper, plastic, rubber and cardboard.
Solder electrical wiring and circuits
10
• Class B fire – These occur because of flammable liquids such as petrol, oil, paint,
kerosene and solvents.
• Class C fire – These occur from flammable gases such as oxy-acetylene, CNG
and LPG.
• Class E fire – These are electrical fires arising from motors, generators, light fittings,
switches, switchboards and cables.
Preventive measures
➢ All workers in an automotive workshop must have responsibilities to ensure that –
a) All flammable waste is appropriately disposed
b) All flammable liquids are sealed and stored
c) Fire hazards are reported to the designated supervisor
d) Damaged electrical equipment is never used
Figure 6: Fire hazards in workshop
➢ Set off the fire alarm so that everybody is made aware of the danger, and make
sure to call 000 for the police and fire service. Provide callers name, the company
name, the address, on-site location of the fire and the extent of the fire.
➢ Stay low if the workshop is filled with smoke.
➢ Use the fire extinguisher to fight the fire if possible.
➢ If the fire is beyond control, evacuate the workplace immediately.
➢ Do not re-enter until the all clear is given.
➢ Ensure that a safe escape route is always maintained in the workshop.
Solder electrical wiring and circuits
11
Firefighting equipment
Firefighting equipment is designed to protect the individuals by extinguishing the fire.
The equipment can be used by trained firefighters or any untrained person at the
scene of a fire.
There are several types of firefighting equipment:
➢ Fire Extinguishers
➢ Fire Blankets
➢ Fire Hose Reels
➢ Signage
➢ Sprinklers
➢ First Aid Kits
➢ Smoke Alarms
Figure 7: Fire extinguishers
1. Water fire extinguishers –
• These extinguish the fire by taking away the heating element from the fire
triangle.
• These are used for class A fire. It should not be used for class B and C fires as it
increases the hazards.
• Never use electrical equipment.
Solder electrical wiring and circuits
12
2. Foam fire extinguishers –
• These separate the oxygen elements from other elements.
• These are water-based and consist of a foaming agent.
• Foaming agent has a blanketing and rapid flame knockdown effect. It stops the
flames and seals vapours thus preventing re-ignition.
• Suitable for class A and B fires.
3. Dry chemical powder –
• They extinguish the fire by interrupting the chemical reaction of the fire triangle.
• It creates a barrier between the oxygen element and the fuel element on class A
fires.
• It is effective on Class A, B and C fires.
4. Wet chemical –
• It extinguishes the fire by removing the heat and re-ignition is prevented.
• It also creates a barrier between the oxygen element and fuel element
• It is used on Class A fires in commercial kitchens.
• Never use a wet chemical fire extinguisher on Class B fires.
5. Carbon dioxide –
• They remove the oxygen from the fire triangle.
• They also help in removing the heat with a very cold discharge.
• They are used on Class B and C fires. They are ideal for electrical fires also as CO2
does not leave any harmful residue.
• They are ineffective on Class A fires.
Using a fire extinguisher:
Installation of fire extinguisher must be according to Australian standard AS2444
Portable Fire Extinguishers and Fire Blankets selection and location.
➢ First, pull the pin. Hold the extinguisher with the nozzle directing away. Now,
release the locking mechanism.
Solder electrical wiring and circuits
13
➢ Point the extinguisher at the base of the fire.
➢ Squeeze the lever slowly and evenly.
➢ Sweep the nozzle from side to side.
Always keep back to a clear exit so that individual can escape quickly and easily in
situations where fire cannot be controlled. Also, leave the area immediately if it is
filled with smoke.
Figure 8: Operation of fire extinguisher
Fire Hoses
Fire hose is another type of firefighting equipment which carries water or another fire
retardant like a foam to extinguish the fire. It is attached to a fire hydrant or a fire
engine. Fire hose reel releases a high stream of water and extinguishers large fires.
They are ideal for Class A fires.
Figure 9: Fire hoses
Solder electrical wiring and circuits
14
Fire hydrant system
The system includes pumps, tanks, fire brigade booster etc. They are used to stop
heavy fires as they carry large amounts of water. The water is supplied with enough
pressure through pipes. Fire hoses are also part of the fire hydrant system.
Figure 10: Fire hydrant system
Fire blankets
These are used in small fires that occur in workplace vehicles. It consists of a fire-
resistant fabric which is used to reduce small fires. It can be wrapped around a
person. They are made of wool with a specially treated chemical and are
flameproof.
Figure 11: Fire blankets
Other equipment
➢ Sprinklers
➢ Water and sand bucket
➢ Firefighting clothing – Protective suit, Safety helmet etc.
Solder electrical wiring and circuits
15
Fire evacuation plan
➢ Activate the fire alarm.
➢ Call 000 in case of a fire emergency and provide necessary details.
➢ Assist the injured only if it is safe to do.
➢ Following emergency exit routes to leave the area.
➢ Never use elevators to evacuate the building.
➢ Use fire extinguishers and other firefighting equipment if the individual is trained
and if it is safe.
➢ Stay low in the presence of smoke.
➢ Follow the instructions of emergency services personnel and chief wardens.
Figure 12: Evacuation signages
Fire warning alarms must be installed in all buildings to decrease the severity of
workplace accidents. The alarms alert the people in the workplace to any fire
outbreak before it becomes life-threatening. The warning alarms must provide a
sound level which is clearly heard throughout the workplace. All the workers must be
accustomed to the warning alarms.
Figure 13: Fire alarm
Solder electrical wiring and circuits
16
2.4 First aid
• Immediately place the burns under cold water for 15 minutes.
• Cool the affected area with cold running water for several minutes.
• Remove rings before swelling starts.
• Apply a sterile dressing to protect against infection.
• Do not apply lotions, ointments etc., nor prick any blisters.
• Seek professional medical advice where necessary.
• Report to the supervisor and medical consultant regarding the injury.
2.5 Environmental requirements
Waste Management
Soldering waste from the lead soldering and another metal soldering like silver
soldering is considered harmful. Discard lead solder and trap in a container with a
lid. The collection container should be metal and labelled
Waste management of the solder waste includes 3 important processes – trapping
storing and disposing of.
Figure 14: Waste storage
Trapping:
• Collect solder waste in a labelled lidded container and always close the lid when
not in use.
• Label the container as per the local safety authorities to dispose of the solder
waste.
• Use solder sponges to clean and wipe the solder waste together.
Solder electrical wiring and circuits
17
• Used solder sponges and contaminated rags should be collected in a sealable
bag for disposal as hazardous waste.
Storing:
Store the lidded waste containers in the soldering location. Make sure there is no
contamination in the stored container and once the container is filled, seal the
container. Always maintain a single trapping container in the soldering location and
label the container. Only one trap container is allowed at each soldering location.
Disposing:
Once the containers are filled with the solder waste, they should be sealed such that
they do not contaminate the surroundings and inform the local disposing
contractors to remove the filled containers from the work area. Make sure the
disposing of is done promptly.
Solder electrical wiring and circuits
18
3 Planning and preparation
3.1 Service information
Figure 15: Service manuals and reports
The manufacturer specifications, workplace procedures and other technical
information relating to vehicle repair and diagnosis in a workplace can be obtained
from the organization’s website or Manager’s office.
Manufacturer specifications regarding usage of the soldering equipment are listed
below:
• Various systems and system wiring diagrams
• Safety precautions to be exercised while working on soldering system
• Component specifications such as voltage, resistance, material specifications.
• System diagnostic procedures
• Repair instructions
• Diagnostic trouble code descriptions
• Installation procedures
• Final inspection procedures
Service manuals
Factory and aftermarket service manuals, also called as workshop manuals contain
vehicle specifications and service procedures. Factory service manuals cover one or
more models of the same vehicle for a year, while aftermarket service manuals
cover multiple years and/or models in one manual.
Solder electrical wiring and circuits
19
Service manuals include the following:
• Capacities and recommended specifications for all fluids
• Specifications including engine and routine maintenance items
• Testing procedures
• Service procedures including the use of special tools when needed
• Component location information.
• Diagnosis symptoms and flow charts.
While some factory service manuals are printed in one volume, most factory service
information manual is printed in several volumes due to the amount and depth of
information presented. The typical factory service manual is divided into 2 sections.
a. General information
General information includes topics such as:
• Warnings and cautions
• Vehicle identification numbers on the engine, transmission/transaxle and body
parts
• Fastener information and Lock cylinder coding
• Decimal and metric equivalents
• Abbreviation and standard nomenclature.
b. Technical service bulletins
The manufacturer provides information to technician or service personnel on
unexpected problems, updates, or changes in the repair procedures that occur with
a vehicle system, part, or component as an update in a bulletin called the Technical
service bulletins (TSBs).
The TSB consists of the algorithm of service and diagnostic procedures to understand
and identify the fault to perform effective repair.
Technical service bulletins are different from the service information and the repair
procedure as service information and repair manuals are prepared by the
manufacturer while manufacturing the vehicles and include the information of
service requirements of the vehicle. TSB consists of the service procedures of the
unexpected failures which need the changes in the service procedure.
Solder electrical wiring and circuits
20
Note:
• The technician with the right skill and knowledge on the vehicle must know where
to exactly stop the diagnosis.
• The technician should be aware of the seriousness of damage that may be
caused while working on the critical system.
• The person should know his limitations in dealing with every component as it may
cause huge damage to the system.
Hazard communication requirements
The following OSHA requirements must be implemented:
✓ Inventory—Solder wires and fluxes must be included on the laboratory’s chemical
inventory.
✓ Material Safety Data Sheets (MSDS) must be on file in the work area. Request
these from supplier if they were not provided at the time of purchase.
✓ Training and education of employees working with hazardous materials must be
documented.
3.2 Workplace preparation
The preparation of the soldering tool to connect the wires in the wiring repair process
involves the cleaning and tinning of the soldering iron:
• Switch on the soldering iron and leave it to heat up.
• When the soldering iron is heated, clean the tip of the iron by wiping the tip of the
soldering iron with a damp sponge. Always use a damp sponge to frequently
clean the tip of the iron.
• Once the cleaning is done, tin the tip of the soldering iron by applying the light
coat of the solder to the tip. Tinning the tip of soldering iron helps the solder flow
more freely once it heats up.
3.3 Safety data sheets
It is a sheet that contains the information for chemicals used in workshop. It consists
of the following details:
• Safe handling procedure
• Storage procedure
Solder electrical wiring and circuits
21
• Manufacturer chemical ingredients details
• Physical properties
• Precautions
• Safety Handling.
SDS must provide information on the:
• Hazards of the chemical and how to handle it safely, including storage and
disposal.
• Physical and chemical properties of the chemical, as well as potential health and
emergency response measures.
• Environmental effects of the chemical.
Figure 16: Sample solder flux SDS
This information must be set out using the following section headings, with further
detail available in the Model Code of Practice for the Preparation of Safety Data
Sheets for Hazardous Chemicals:
Section 1—Identification: product identifier and chemical identity
Solder electrical wiring and circuits
22
Section 2—Hazard(s) identification
Section 3—Composition and information on ingredients
Section 4—First aid measures
Section 5—Firefighting measures
Section 6—Accidental release measures
Section 7—Handling and storage, including how the chemical may be safely used
Section 8—Exposure controls and personal protection
Section 9—Physical and chemical properties
Section 10—Stability and reactivity
Section 11—Toxicological information
Section 12—Ecological information
Section 13—Disposal considerations
Section 14—Transport information
Section 15—Regulatory information
Section 16—Any other relevant information.
The SDS for the solder flux and wax is issued by the manufacturer which includes the
above information. The solder flux includes the hazardous material made of lead;
hence the SDS includes all the necessary information related to the safe handling of
the Lead.
3.4 Tools and equipment
3.4.1 Soldering iron
A soldering iron is a handheld tool used for soldering. The assembly of the tool
includes a metallic tip with an insulated handle. When the tool is operated by
providing the current, the metallic tip provides heat to the solder.
The solder is a metal alloy which fuses into the gap between the two metals and
joins together. When the solder is heated the material melts and fuses between the
metal to join them permanently.
Solder electrical wiring and circuits
23
Figure 17: Soldering iron
Different types of soldering iron can be selected based on the type of operation,
material to be used on and the application of the soldering iron.
3.4.1.1 Soldering pencils
Soldering pencils are the best and the cheapest soldering iron. These are easy to
use, and compact design makes the storage convenient. These are not suitable for
commercial usage as they do not involve in temperature control.
• Soldering pencil – Repairs where AC is not used
Figure 18: Soldering pencil
3.4.1.2 Soldering gun
The soldering gun is a bit advanced to the soldering pencil used for the normal
soldering applications. The major difference of the soldering gun and the soldering
pencil is the warm-up time of the latter.
Solder electrical wiring and circuits
24
This includes a transformer to convert 110v AC to lower voltage and another
transformer to produce hundreds of amperes of current. This produces high current
using the transformers and this leads to the quick heat up of soldering tip. The
soldering guns are expensive when compared to soldering pencils.
• Soldering gun – Automotive repairs and general electrical works
Figure 19: Soldering gun
3.4.1.3 Soldering stations
The soldering station is an assembly of the soldering pencil and the power station
which also helps in adjusting the temperature of the soldering tip. The advanced
soldering stations come with electronic temperature control for accuracy. This will
not only heat up the soldering tip to recommended temperature but also maintains
throughout the operation.
• Soldering Stations - Manufacturing
Figure 20: Soldering station
In the commercial facilities for the electrical wiring repairs and rework, repair stations
are used. This includes the complex soldering systems made of different components
Solder electrical wiring and circuits
25
like soldering iron, thermo tweezers, desoldering unit and the hot air gun. Some
assemblies include the cleaning equipment also. The rework stations are expensive
when compared to the soldering pencils and guns.
Figure 21: Rework stations
• Soldering systems (Rework/repair stations) – Desoldering and laboratories.
The selection of the appropriate soldering iron includes the following considerations:
Wattage: Wattage of the iron is the most important consideration while choosing the
soldering iron. Soldering irons range between 20W-60W. The solder with 50W is the
ideal one.
• Temperature control: The application defines the temperature control. Some
operations require temperature control while working on the typical electronic
systems and some does not require temperature control.
• Tip size and shape: The tip cannot be changed on the soldering iron. Hence,
choosing the correct soldering iron tip with specific shape and size is important for
the operation.
Methods to holding components to be soldered
a) When solder is used on electronic components, the heat can damage them if it
is not controlled. To absorb heat, a pair of pointy-nose pliers can be used to hold
the wire on the component side of the soldering
b) Electrical wiring can be twisted or bound at the joints before soldering. This holds
the wires together during the soldering process
c) Ask a colleague to hold the wires to perform the soldering operations
d) Use soldering stand which has crocodile clamps for holding the wires to be
soldered.
Solder electrical wiring and circuits
26
4 Soldering
Figure 22: Soldering circuits in automobiles
Soldering is a process used for joining metal parts to form a mechanical or electrical
bond. It typically uses a low melting point metal alloy which is melted and applied to
the metal parts to be joined and this binds to the metal parts and forms a
connection when the solder hardens.
Soldering is different from welding in which the parts being joined are not melted
and are usually not the same material as the solder.
Soldering is a common practice for joining or assembling electrical components and
wiring. Soldering can be used for plumbing; sheet metal fabrication or automotive
radiator repair. The techniques and materials used are different from those used for
electrical work.
Components for soldering procedure
Figure 23: Soldering components
Solder electrical wiring and circuits
27
A. Component A – Printed circuit board or PCB
B. Component B – Soldering iron stand
C. Component C – Wire clippers
D. Component D - Solder
Soldering is a complicated skill which comes with practice. The ability to solder
effectively will determine how well the prototype or product functions during its
lifespan.
Poor soldering can be an expensive business - causing product failure and
downtime, engineer's maintenance time and customer dissatisfaction. Following the
bad soldering technique can cause major damage.
4.1 Operation of soldering
The soldering methods used for wiring and plain circuit boards are same for both
production and repair work. For the printed circuit boards, the production methods
and repair methods are different.
In the production of the PCB boards, the dip soldering method is used as several
connections are made at the same time. In the soldering repairs, the joints are made
individually using the general technique of soldering wires with special care to
prevent thermal damage to the heat-sensitive and closely packed circuit elements.
Typical Soldering Operations
a. Tinning
Tinning is a preparatory action for the joining of wires or cables. The tinning operation
applies coating or fills the wires or connectors with the solder, such that the wires can
be melted together easily. During the tinning, apply the tip of soldering iron to the
wire and apply the solder coat freely.
Figure 24: Tinning procedure
Solder electrical wiring and circuits
28
b. Soldering
The tinned wires and cables are inserted into solder cups of terminals, or
mechanically wrapped or twisted terminals. The twisted connections and the
activated soldering iron are introduced to the terminal or joint to melt the solder and
fuse the joint.
Figure 25: Soldering procedure
Soft Solder
Soft solder is an alloy consisting of various combinations of tin and lead, with silver
and other additives, which melts at temperatures below 370ºC. It may be in a bar
form to be melted for tinning or in the form of rosin cored wire to use with a soldering
iron.
Hard Solder
The hard solders are mostly confused with high-temperature soft solders. Hard solder
is a silver alloy used when greater mechanical strength and high temperature
exposure is required. When silver soldering electrical equipment or fittings, use
brazing alloy-silver, which is cadmium free, and flux coated brazing rod as per
federal specifications.
4.2 Heat application method of soldering
The heat application method is most commonly used method for soldering joints in
automotive electrical wiring by means of an electrically heated, hand-held
soldering iron. In addition to the conventional iron, a pencil iron is frequently used.
Pencil irons, except for their smaller size, are identical to conventional irons and are
used for precision soldering of small units and minor circuit assemblies.
4.2.1 Resistance soldering
Resistance soldering is frequently used in large volume production where the
operation is standardized. In this method, a low voltage transformer is used and the
metal to be soldered is heated by the resistance to a flow of electric current. The
Solder electrical wiring and circuits
29
work metal is gripped between two electrodes, completing the circuit and heating
the metal for soldering.
Figure 26: Resistance soldering
In another application, a carbon pencil is used as one electrode and the metal to
be soldered forms the other electrode. When contact is established through the
carbon pencil, intense heat is generated at the point of contact. Resistance
soldering is well adapted to the soldering of small parts or for crowded assemblies
where it is desired to restrict heat to a small part of the assembly.
4.2.2 Torch Soldering
Torch soldering is used where high heat is required - as in silver soldering. This process
is suitable for soft-soldering work which is not part of an assembly or when the part to
be soldered can be removed for soldering.
For example, wires may be torch soldered to large contracts that have been
removed from connectors. Torch soldering is not suitable for soldering small parts.
Figure 27: Torch soldering
Solder electrical wiring and circuits
30
4.2.3 Dip Soldering
Figure 28: Dip soldering
Dip soldering is the process of immersing connections in molten solder; one or more
connections can be made in a single operation. This process is used on printed
circuits, where the conductor pattern is on one side of the board and the
components on the opposite side. Joints are mechanically secured, dipped first into
flux, then into molten solder.
4.3 Soldering flux
A flux is a chemical purifying agent. In soldering metals, flux provides three functions:
it eliminates rust from the components to be soldered; it closes air out as a result
ending extra rust, and by making easy mix improves dripping individuality of the fluid
solder.
Figure 29: Soldering flux usage
When the solder melts and forms a joint between two metal surfaces, it forms a
metallurgical bond by chemically reacting with the other metal surfaces. A good
bond requires two things: a solder that is metallurgically compatible with the metals
Solder electrical wiring and circuits
31
being bonded and good metal surfaces free of the oxides, dust, and grime that
prevent good bonding.
Remove grime and dust by cleaning the surfaces or preventing them with good
storage techniques. Oxides, on the other hand, need another approach.
Oxides are formed on almost all metals when oxygen in the air reacts with the metal.
Oxidation on iron is commonly called rust, but oxidation affects tin, aluminium,
copper, silver and nearly every metal used in electronics. Oxides make soldering
more difficult or even impossible, preventing a metallurgical bond with the solder.
Oxidization happens all the time, but it happens much faster at higher temperatures
— like when soldering flux cleans metal surfaces and reacts with the oxide layer,
leaving a surface primed for a good solder bond.
Flux remains on the surface of the metal while soldering, which prevents additional
oxides from forming due to the high heat of the soldering process. As with solder,
there are several types of flux, each with key uses and some limitations as well.
4.3.1 Types of flux
For many applications, the flux included in the core of the solder wire is enough.
However, there are several applications where the additional flux is extremely useful,
such as surface-mount soldering and desoldering. In all cases, the best flux to use is
the least acidic flux that will work on the oxides of components and result in a good
solder bond.
4.3.1.1 Rosin flux
Rosin flux is one of the oldest types of flux based on refined and purified pine sap.
Rosin flux is still used nowadays with the different flux blends to enhance its
performance. The flux flows easily to remove oxides quickly and helps to remove
foreign particles from the surface of the metal being soldered.
Figure 30: Rosin flux
Solder electrical wiring and circuits
32
Rosin flux is acid when liquid, but when it cools it becomes solid and inert. As rosin
flux is inert and solidifies, it can be left on a PCB without harming the circuit until the
circuit will warm to the point where the rosin may become liquid and start
distributing away at the connection.
• Rosin Flux – PCB, Copper wires, semi-conductors
4.3.1.2 Organic acid flux
Organic acid flux is one of the common water-soluble organic acid fluxes. Weak
acids like citric, lactic and stearic acids are used in organic acid flux. The weak
organic acids are combined with solvents like isopropyl alcohol and water.
Organic acid fluxes are stronger than rosin fluxes and clean the oxides much more
quickly. Additionally, the water-soluble nature of the organic acid flux allows the PCB
to easily clean with regular water and protect components that should not get wet.
As the organic acid residue is electrically conductive and will affect the operation
and performance of a circuit, remove the flux residue when soldering is completed.
• Organic Acid Flux – Reflowing soldering through hole components
Figure 31: Organic acid flux pen
4.3.1.3 Inorganic acid flux
Inorganic acid flux works better with stronger metals such as copper, brass and
stainless steel. It's a blend of stronger acids like hydrochloric acid, zinc chloride, and
ammonium chloride.
Inorganic acid flux requires complete cleaning after use to remove all the corrosive
residues from the surfaces, which will weaken or destroy the solder joint if left in
place. Inorganic acid flux should not be used for electronic assembly work or
electrical work.
• Inorganic Acid Flux – Brazing copper pipes
Solder electrical wiring and circuits
33
Figure 32: Inorganic acid flux
4.3.1.4 Rosin core solder
Rosin cores runs through the centre of the solder wire. This embedded rosin flux helps
the solder, flow and bond to the parts being soldered. Solder is also available in a
number of diameters, with 0.02", 0.063" and 0.04" being common solder
diameters. They are commonly used with copper wires and semiconductor
materials.
Rosin core solder has channels inside filled with rosin flux. As flux melts before the
solder, the embedded flux automatically cleans the joint before the solder flows into
it. Rosin core solder should always be used for electronics. Both lead and lead-free
solder can be filled as rosin core.
Never use acid core solder for electronics as it is intended for plumbing and sheet
metal work only, and the acid residue will corrode and ruin electrical joints. Acid flux
remains chemically active at room temperature, while rosin flux becomes inert and
harmless once the joint cools.
Application – Electrical appliances, wiring and finer electronic work
Solder electrical wiring and circuits
34
5 Soldering electrical wiring and circuits
The soldering wire or a circuit includes the following procedures like:
• Cleaning the area before the solder
• Selection of the solder and soldering tip
• Selection of the heating capacity as per the manufacturer
• Selection of the soldering iron
• Holding the joint safely
• Applying the heat and solder and time to apply the solder
• Holding the soldering iron
• Cooling the soldering join
• Cleaning the solder after the solder
• Final inspection of the joint
5.1 Soldering iron tip selection
The size and shape of the soldering iron tip will influence the rate of heat transfer.
Larger tips with more surface area will transfer heat faster than smaller tips.
Figure 33: Soldering iron tips
Solder electrical wiring and circuits
35
Tip size is based on the size of the component. While there is no exact rule about
how the size of a soldering iron tip should compare to the size of the termination, if
the tip extends too far beyond the edges of the joint, it could come in contact with
another component or the surface of the board. Where possible, the width of the
soldering iron tip should be slightly smaller than the width of the pad.
5.2 Component removal tip selection
The size and shape of the component removal tip will influence the rate of heat
transfer. Larger tips with more surface area will transfer heat faster than smaller tips.
5.2.1 Vacuum desoldering tip selection
The smallest tip should be selected providing that the tip fits over the component
lead and allows room for molten solder and air to pass through it. The outside
diameter of the tip should not cover the pad completely or touch the circuit board
base material or solder mask. If the tip extends too far beyond the edges of the joint,
it could meet another component or the surface of the circuit board.
5.2.2 Hot air tool tip selection
The smallest tip should be selected providing that the proper airflow is delivered to
the leads and solder joints. If the tip is too large it may extend beyond the edges of
the component and cause reflow to adjacent components or burn the surface of
the circuit board.
Good solder joints
The joints are acceptable when they are shiny, concave in nature and free of dirt. It
must fully cover the pad on which the components pass through.
Cold solder joints
These joints must be rejected since they are dull, convex in nature and not oxidation
free. They must be resoldered.
5.2.3 Conductive tool tip selection
The smallest tip should be selected providing that the tip fits over the entire
component and contacts all the leads evenly. If the tip is too large it may extend
beyond the edges of the component and contact another component or the
surface of the circuit board.
Solder electrical wiring and circuits
36
5.3 Preparing for the soldering
Each workplace will have its own policies and procedures and practices. Electrical
wiring diagrams must be referred for correct requirements. However, the following
are basic and vital in performing the soldering process:
• Anti-static protection (mats)
• Clean surfaces & ventilation
• Removal of surface oxidation
• Manufacturer specification to be followed for soldering iron selection as per the
material to be soldered.
Preparation procedures also include:
• Once the tools are pre-inspected and arranged, plug in soldering iron and let it
heat up.
• Leave the soldering iron until it heats up to 800 degrees Fahrenheit.
• Always apply the solder to the tip of the new soldering iron before using.
• Once the iron reaches the required temperature, clean the tip of the iron on a
wet sponge or damp sponge or steel wool by gently touching the tip of the
soldering iron to the sponge and clean off any old bits of solder that might be
stuck to it.
• Hold solder wire as recommended by cutting a piece of it off the roll, and then
makes a coil at one end with a short lead at the other which eases holding it
steady and apply just the right amount of solder.
• Adhere to the manufacturer specification of soldering material as per the
soldering joints like wire to wire or wire to lead or on the PCB board.
• Soldering electrical components on a circuit board need less preparation. Hold
them in the position to be seated in the board using clips.
5.4 Cleaning and preparation
Cleanliness is important in the soldering operation. Soldering should be done in a
clean, dust free environment.
A. Keep cleaning solvent such as parts cleaner, electrical terminal cleaners,
electrical wiring corrosion removers in dispensing bottles to avoid cold joints.
B. Place the soldering iron in its stand and plug it in.
Solder electrical wiring and circuits
37
C. Wait for the soldering iron to heat up.
D. Moisten the sponge with cleaning solvent.
E. Wipe the tip of the iron on the damp sponge. This will clean the tip.
F. Melt a little solder on the tip of the iron (This is called tinning and check the
manufacturer's instructions related to tinning the tip).
Preparation procedures for cleaning also includes:
• Ensure the soldering operation is not performed in the colder areas so that the
soldering iron will not be cooled.
• Parts contaminated with dirt, oil, grime, grease, etc., cannot be successfully
soldered.
• Ensure that the parts are mechanically clean before soldering.
• Clean the parts with a cloth or brush dipped in alcohol or other approved solvent.
• Badly corroded parts may be cleaned using the special procedures.
• Use abrasive brushes to clean the component mechanically before soldering.
Figure 34: Soldering iron tip cleaning
Before inserting a component into a plated through hole for through-hole soldering,
or onto pads for surface mount soldering, it is necessary to remove any excess
solder.
• If a component was previously soldered at the rework location, it leaves the older
solder residue as the solder has already been heated twice. Repetitive soldering
may affect the physical composition of the metals as every time the solder is
reheated, the molecular structure tends to become increasingly brittle.
Solder electrical wiring and circuits
38
• The solder needs to remain ductile in order to absorb the stresses of expansion
and contraction caused by heating and cooling.
• Excess solder in a plated through hole or excess solder on surface mount pads
may interfere with the proper placement of the new component.
5.4.1 Plated through hole preparation
5.4.1.1 Vacuum desolder tool method
Solder removal by absorbing or drawing is not recommended for removal of solder
from a plated hole. A powered vacuum desoldering tool is recommended.
The powered vacuum desoldering tool has a heated tip with a hole in the centre to
vacuum melt solder away. There are different tip sizes depending on the size of the
job. The diameter of the tip should match the width of the pad. A larger tip will
extend over the edge of the pad and could potentially burn the board.
• Clean the area to be soldered.
• Inspect the hole. If there is not enough solder covering the pad to provide proper
heat transfer, the hole should be filled with solder.
• Filling the hole improves the thermal linkage between the desolder tooltip and the
solder in the hole. This ensures a rapid melt and reduces the possibility for pad or
hole damage.
• Place the heated desoldering tip onto the pad until the solder melt. Do not apply
any downward or sideways pressure on the pad.
• After the solder melts, activate the vacuum and suck the solder through the hole
in the tip into the solder storage chamber.
• It should only take a few seconds for all the solders to be removed.
• After the solder is vacuumed from the hole, lift the tool and continue the vacuum
for an additional few seconds to make sure that the solder has had enough time
to travel through the tip into the storage chamber.
• If needed, remove solder from the remaining holes so that the component can
be inserted without force.
• Clean the area.
Solder electrical wiring and circuits
39
5.4.2 Surface mount pad preparation
5.4.2.1 Solder Braid Method
Solder Braid is made from copper with a powdered flux inside the copper strands.
Solder braid will absorb the solder when the heat is applied to the braid and solder
surface.
• Solder braid comes in different widths. Select a size that matches the width of the
pad, or just slightly smaller, where possible.
Note: Most solder removal braid comes with a powdered flux inside the copper
strands. Adding additional flux will help to transfer the heat faster and helps to
improve the absorption or capillary action of the copper braid.
• Select a soldering iron tip to match the width of the pad. If the tip is too large for
the braid; it will hang over the edges and could burn the board or the solder
mask. If the tip is too small, it will take much longer to heat up the braid.
• Add a small amount of liquid flux to the braid.
• Place braid over the pad and rest the iron tip on the braid.
• Apply the heat; it is important to avoid putting any downward or sideways
pressure on the pad since the adhesive resin underneath the pad is being heated
at the same time.
• Adhesion between the circuit board and the pad is at its weakest when heated.
Sideways pressure against the pad can lift the pad off the circuit board surface.
The weight of the soldering iron should apply enough contact to heat the solder
braid quickly. The heat that passes through the braid should melt any solder that
remains on the pad within a few seconds.
5.4.2.2 Vacuum desolder tool method
The powered vacuum desoldering tool has a heated tip with a hole in the centre to
vacuum (absorb) melted solder away. There are different tip sizes depending on the
size of the job. The diameter of the tip should match the width of the pad. A larger
tip will extend over the edge of the pad and could potentially burn the board.
• Apply a small amount of liquid flux to the pad.
• Place the heated tip onto the pad until the solder melt. Do not apply any
downward or sideways pressure on the pad; the weight of the hand-piece tip is
enough.
Solder electrical wiring and circuits
40
• After the solder melts, activate the vacuum and suck the solder through the hole
in the tip into the solder storage chamber.
• It should only take a few seconds for all the solders to be removed. After the
solder is vacuumed from the pad, lift the tool. Continue the vacuum for an
additional few second to make sure that the solder has had enough time to travel
through the tip into the storage chamber.
• Any other pads should be prepared exactly like the first.
• Clean the area.
5.5 Soldering operation
• Make sure the joint is mechanically secure with the holding equipment like
tweezers. Possibly make sure that the joint is held rigid during the cooling period
when the joint cannot be held securely.
• Apply flux-core solder at the exact point between the metal and the soldering
iron and hold the iron directly against the assembly.
• Melt the solder on the joint.
• Place the soldering iron firmly against the junction.
• Do not apply heat to the work any longer than the time necessary to melt the
solder on all parts of the joint.
• Do not use excess solder than recommended.
• Do not pile up solder around the joint, as this results in difficult inspection and
material wastage.
• Ensure proper care should be taken while working on the silver-coated wire to
prevent absorption during solder application.
• When the soldering iron is not in use, keep it in a holder. This will protect the
operator against burns and the iron against damage.
• When the solder joint has been made, hold the work firmly in place until the joint
has set.
• Disturbing the finished work will result in a mechanically weak joint, with high
electrical resistance.
• Allow solder joints to cool naturally. Do not use liquids or air blasts.
Solder electrical wiring and circuits
41
• If the correct amount of solder is used and instructions are followed carefully,
there should be no or little excess flux remaining on the finished joint.
• If cleaning is necessary, remove excess flux by brushing the joint with a stiff brush
dipped in methyl alcohol or a similar approved solvent.
• Use alcohol carefully and avoid contact between alcohol and wire insulation.
• For cleaning printed circuit connections, use a cotton gauze stick for small areas
and a lint-free clean cloth for larger areas and board edges.
5.5.1 Soldering wires/ electrical connections
1. Safely position the soldering iron while it is heating up. While the soldering iron is
heating, remove an appropriate amount of the protective insulation from the
wires with wire strippers.
2. Twist the wires together to make a good mechanical connection between them.
3. Tint the soldering iron tip and gently heat up the wires while placing the solder
opposite to the soldering iron.
4. Identify a good solder joint and confirm solder has been drawn into the joint
completely.
5. Once the electrical connection has been made, slide insulator sleeve cover over
the joint and use a heat gun to shrink the tubing around the joint.
6. Place the heated iron onto the terminal to get it hot enough to melt the solder
applied to the end of the crimped wire tabs.
7. Take care not to use too much solder as the wire insulation starts to melt if the
terminal gets too hot.
8. Once the electrical connection has been made, wait for it to cool down without
moving the solder joint.
9. Once it is cool enough, place the heat-shrink tubing over the terminal, heat it up
with a heat gun, and place the connection into service.
Methods of holding components to be soldered:
1. When solder is used on electronic components, the heat can damage them if it is
not controlled. To absorb heat, a pair of POINTY-NOSE pliers can be used to hold
the wire on the component side of the soldering.
2. Electrical wiring can be twisted or bound at the joins before soldering. This holds
the wires together during the soldering process.
Solder electrical wiring and circuits
42
3. Ask a colleague to hold the wires so you can perform the soldering operations.
4. Use soldering stand which has crocodile clamps for holding the wires to be
soldered.
5.5.2 Desoldering
Desoldering is the process of removing solder at a joint to disconnect two
components, wires or materials.
One might have to replace a component that's gone bad, or if there is any change
in the design. To desolder wires, one can just heat up the connection and wiggle
them around until they come free. If there is slack, just cut the wire at the
connections, strip, and resolder as necessary.
With leads that are mounted through holes on a circuit board, it takes a little more
concentration. To desolder something delicate, it’s best to use a desoldering pump,
or bulb which will suck up the molten solder and remove it from the joint. Soldering
wicks or braided copper wire also work well to suck up unwanted solder.
5.5.3 Fixing mistakes
Soldering is pretty forgiving, and it’s usually pretty easy to fix a mistake. If one has to
put down a little too much solder or position something incorrectly, reheat the joint,
melt the solder, and then reposition the component as needed.
Solder can be heated and cooled as many times needed to get the joint the way
needed.
Solder electrical wiring and circuits
43
6 Work completion procedures and documentation
6.1 Final visual inspection of soldered connections
• Visually inspect the electrical connections for loose joints or cold joints
• Once soldered area is cool, inspect the joint, it should be shiny and firm
• Clean any excess flux from the joint
• Inspect the continuity of the solder joints
• Check that the insulators are fixed properly
• Inspect the circuit or system for working condition
• No evidence of burnt smell when system is On
• Inspect flexible and spiral plastic conduit
• Make sure no moisture or water entered the systems.
• During the final inspection of the soldered joint, the joint will have a bright silvery
appearance, with smooth fillets and feathered non sharp, edges and the entire
joint will be covered with a smooth even coat of solder, and the outline of the
joint will be visible.
Figure 35: Final inspection of soldered joint
✓ Inspect the poor soldering joint with the following conditions:
• Dull grey, chalky, or granular appearance - evidence of a cold joint.
• Hair cracks or irregular surface - evidence of disturbed joint.
• Greyish, wrinkled appearance - evidence of excessive heat.
• Partially exposed joint - evidence of insufficient solder.
Solder electrical wiring and circuits
44
• Scorched wire insulation or burned connector inserts.
Figure 36: Final inspection of soldered circuit board
Post soldering clean-up procedure
Clean the flux left behind by the solders from the electrical circuits. Use cleaning
solvents to remove flux. Wipe down the work area surfaces with sponge, since they
involve chemicals. Wash hands with soap and water to get rid of contamination.
Choosing solvents for cleaning must withstand very high temperatures.
6.2 Post-soldering insulation
Most electronic repairs involve at least some degree of soldering and wiring. Many
projects have a printed circuit board, PCB. The connections that are made to many
of these items will be exposed. In many cases, it is not a problem to expose, but for
others, it is not wise to leave the connections exposed.
Sleeving is particularly true when connections carry high voltages. Special sleeves
must be used to protect such connections. Additionally, sleeves can be used when
wiring small multiway connectors where exposed wires could bend slightly and short
to one another. Using sleeves prevents accidental short circuits.
6.3 Types of sleeves and sleeving
There are several ways in which exposed terminals and soldered connections can be
insulated and protected from being accidentally touched.
Solder electrical wiring and circuits
45
Methods of insulating solder joints:
Figure 37: Protection of soldered joints with sleeves
Heat shrinks: Heat-shrink terminals are a shrinkable plastic tube used to insulate wires,
providing abrasion resistance and environmental protection for electrical joints and
terminals. They are fast to fit and waterproof and mostly used to minimise the risk of
inhaling solder and resin fumes.
Liquid Tape: Liquid Tape is a rubber coating for solder joint insulation. The flexible
coating exhibits excellent protection from acid, alkaline, and abrasion, as wells as
sealing out moisture and salt permanently. Liquid Tape has the strongest dielectric
protection.
PCV Insulating tape: It's typically made of slightly stretchy PVC vinyl, and is backed
with a pressure sensitive rubber-type adhesive. It has good insulative properties and is
perfect for protecting wire splices and providing extra insulation on electrical cords.
6.4 Workshop procedures
Post soldering clean-up procedure
Clean the flux left behind by the solders from the electrical circuits. Use cleaning
solvents to remove flux. Wipe down the work area surfaces with sponge, since they
involve chemicals. Wash hands with soap and water to get rid of contamination.
Choosing solvents for cleaning must withstand very high temperatures.
Once the automotive systems are inspected and repaired, follow the below house-
keeping rules:
• Ensure the work area is cleaned and there is no waste lying on the floor.
• Clean and wipe all the oil spills on the floor to avoid slips, trips and falls.
• Do not leave the tools on the workshop floor.
• Clean the tools and equipment after completion of the task.
Solder electrical wiring and circuits
46
• Inspect the tools for physical damages and tagout any faulty tools and report to
the supervisor.
Tagout: The tagout is a safety practice to reduce the risk of technicians using tools
and equipment which are found unsafe or that are in the process of being serviced.
The tagged-out tool avoids the accidental usage of the faulty tools.
Figure 38: Tagout of faulty equipment
• The tools must be stored back in the designated place.
• Precision measuring equipment like dial gauges, Vernier calipers, screw gauges,
etc. and specialist diagnostic tools such as scan tools and multimeter should be
stored in moisture free manufacturer provided containers in line with the
manufacturer’s procedure.
• Adhere to the safe environmental procedures for cleaning and disposing of non-
recyclable materials.
• The recyclable materials must be disposed to the authorized dealer.
6.5 Documentation
It is very important to document the procedure performed on the system before and
after a service or a diagnosis.
Repair Order (RO)
A repair order (RO) is written for every vehicle brought into the shop for service. RO is
also called as service or work orders. ROs contain information about the customer,
the vehicle, the customer’s concern or request, an estimate of the cost for the
services, and the time the services should be completed.
RO is a legal document used for many other purposes, such as payroll and general
record keeping. Legally, RO protects the shop and the customer. Every shop may
enter different information onto the original RO.
Solder electrical wiring and circuits
47
Most ROs contain the following information:
• Complete customer information
• Complete vehicle identification
• The service history of the vehicle
• The customer’s complaint
• The preliminary diagnosis of the problem
• An estimate of the amount of time required for the service
• An estimate of the costs of the parts involved in the service
• The time the services should be completed
• The name or other identification of the technician assigned
• The actual services performed with their cost
• The parts replaced during the services
• Recommendations for future services
• The total cost of the services
Figure 39: Sample repair order
Solder electrical wiring and circuits
48
➢ Diagnostics report
The diagnosis report is a report of diagnosis generated or manually prepared by
the technicians which consist of the following information:
• Complete vehicle information
• The service history of the vehicle
• Concern being diagnosed
• The diagnosis tool and equipment used
• The diagnosed fault codes generated
• The live data, the freeze frame data for the diagnosis done
• The technician’s observations
• The procedure involved to resolve the generated concern.
• The conclusion and summary of the diagnosis.
This data helps the technician in understanding and registering the diagnosis,
making the customer understand the repairs and diagnosis done on the vehicle.
This also helps as a quick reference for the workshop if any complaint arises. And
as per the law, the reports must be procured in the workshop for further
assistance.
Figure 40: Sample diagnostic report
Solder electrical wiring and circuits
49
Importance of documenting diagnostic process
• The technician can keep track of the process e.g. the details of the tests and
their results.
• The technician can see the build-up of information which will help them
eventually recognize the fault.
• The business can communicate accurately with the customer from the start of
the diagnostic procedure until the repair is completed and paid for.
• The business can obtain authority to repair at the appropriate stages as the
procedure is worked through.
• There is an accurate record if there is any dispute over the work done.
• There is a service record that helps as a reference for future jobs.
Solder electrical wiring and circuits
50
7 References
https://safety.eng.cam.ac.uk/safe-working/copy_of_soldering-safety
https://www.safeworkaustralia.gov.au/sds
http://www.techni-tool.com/site/MSDS/488so788.pdf
https://www.howacarworks.com/accessories/working-on-the-wiring-system
https://www.popularmechanics.com/cars/how-to/a643/2705606/
http://jasonkrugman.com/classes/risd/soldering_safety_procedures.pdf
http://econofix.com/wirepair.html
http://www.circuitrework.com/guides/7-1-2.html
* All images are taken from Google and clipart
