This document discusses wave soldering, which is a bulk soldering process used to solder components to printed circuit boards. It involves passing the circuit board over a pan of molten solder that is agitated to form a standing wave. As the board contacts the wave, the components become soldered to the board. While previously used for through-hole components, wave soldering can also be used for surface mount components. It discusses the wave soldering process and some of the equipment involved.

1. WAVE SOLDERING
A SUMMER TRAINING REPORT
Submitted by
MANJEET
Enrollment Number : 07814802813
in partial fulfillment of Summer Internship for the award of the degree
of
BACHELOR OF TECHNOLOGY
IN
ELECTRONICS AND COMMUNICATION ENGINEERING
MAHARAJA AGRASEN INSTITUTE OF TECHNOLOGY
Guru Gobind Singh Indraprastha University, Delhi
2013-2017

2. Maharaja Agrasen Institute of Technology
To Whom It May Concern
I, Manjeet, Enrollment No. 07814802813, a student of Bachelors of Technology (ECE), a class
of 2013-17, Maharaja Agrasen Institute of Technology, Delhi hereby declare that the Summer
Training project report entitled “Wave Soldering” is an original work and the same has not been
submitted to any other Institute for the award of any other degree.
Date: 01/08/2016
Place: New Delhi
MANJEET
Enrollment No: 07814802813
Electronics and Communication Engineering
7E123

3. ACKNOWLEDGEMENT
I am highly grateful to Bharat Electronics Limited, Kotdwara, one of the leading defense
organizations of the nation, for providing me an opportunity to undertake six weeks training at
their manufacturing premises at Kotdwara, Uttarakhand.
It was a great learning experience as I was introduced to various aspects of the working of the
organization, the latest state of the art technologies & machines used in the manufacturing
processes. It was wonderful to see the company striving hard to keep up the national security at
par with the rest of the world. I would like to express my sincerest gratitude towards Mr. Sunil
Srivastava (Sr. Engineer, Human Resource and Development) and Mr. Mohd. Shahid Sami
(Manager) for their regular support and guidance that helped me in successful completion of my
six weeks training. At the end I would like to thank all the staff members of BEL, Kotdwara who
made this training a rich learning experience.
Manjeet
Enrollment Number: 07814802813
7E123/E3

4. PREFACE
With the ongoing revolution in electronic & communication where innovations are taking at the
blink of eye, it is impossible to keep the pace with the emerging trends. Excellence is an attitude
that whole of human race is born with. It is the environment that makes sure that whether the
result of this attitude is visible or otherwise. A well planned, properly executed and evaluated
industrial training helps a lot in including a professional attitude. It provides a linkage b/w the
student and industry to develop an awareness of industrial approach to problem solving, based on
broad understanding of process and mode of operation of organization.
During this period, the student gets the real experience for working in the actual industry
environment. Most of the theoretical knowledge that has been gained during the course of their
studies is put to test here. Apart from this the student gets an opportunity to learn the latest
technology, which is immensely helps in them in building their carrier.
I had the opportunity to have a real experience on many ventures, which increased my sphere of
knowledge to great extent. I got a chance to learn many new technologies and was also
interfaced to many instruments.
And all this credit goes to organization Bharat Electronics Ltd.

5. TABLE OF CONTENTS
S.No. Chapter Page Number
List of Figures and Photographs 01
List of Tables 02
1. Introduction 03
2. Company Profile 04
3. Manufacturing Units 07
4. Wave Soldering 11
4.1 Introduction 11
4.2 Wave Soldering Process 12
4.2.1 Fluxing 12
4.2.2 Isopropyl Alcohol (IPA) 14
4.2.3 Pre-Heating 15
4.2.4 Solder Bath/Pot 19
4.2.5 Solder Wave Zone 19
4.2.6 Hot Air Debridging 22
4.2.7 Cooling Zone 22
5. Wave Soldering Machines 24
6. Conclusion 27
7. References 28

6. 1
LIST OF FIGURES AND PHOTOGRAPHS
S.No. Figure No. Figure Description Page Number
01 Fig.1 Manufacturing Units 08
02 Fig.2 PCB Tray Movement 13
03 Fig.3 Flux Nozzle 13
04 Fig.4 Reservior Tank 14
05 Fig.5 IPA Reservior 15
06 Fig.6 Conveyor 15
07 Fig.7 Wave Soldering (Through Hole Only) 18
08 Fig.8 Reflow Profile (Surface Mount Only) 18
09 Fig.9 Solder Bath/Pot 19
10 Fig.10 Solder Wave Zone 21
11 Fig.11 A simple wave soldering machine 24
12 Fig.12 A new and fully automated wave soldering machine. 25
13 Fig.13 Wave Soldering machine(Automated Lead Free) operated by a
operator
25
14 Fig.14 14 Internal Structure and different zones of Wave
Soldering machine.
26

7. 2
LIST OF TABLES
S.No. Table Description Page Number
01 Manufacturing Units 07

8. 3
CHAPTER 1
INTRODUCTION
1.1 INTRODUCTION
With the ongoing revolution in the field of electronics & communications where innovations are
taking place at the blink of an eye, it is impossible to keep the pace with the emerging trends.
Excellence is an attitude that whole of human race is born with. It is the environment that makes
sure that whether the result of this attitude is visible or otherwise. A well planned, properly
executed and evaluated industrial training helps a lot in including a professional attitude. It
provides a linkage between the student and industry to develop an awareness of industrial
approach to problem solving, based on broad understanding of process and mode of operation of
organization.
During this period, the student gets the real experience for working in the actual industry
environment. Most of the theoretical knowledge that has been gained during the course of their
studies is put to test here. Apart from this the student gets an opportunity to learn the latest
technology, which is immensely helps in them in building their carrier. I had the opportunity to
have a real experience on many ventures, which increased my sphere of knowledge to great
extent. I got a chance to learn many new technologies and was also interfaced to many
instruments.
The word quality holds out different meaning for different people, but for an industry it is most
important and can be defined as ―The totality of features and characteristics of a product /
services that bear on its ability to satisfy given needs.
And all the credit goes to organization Bharat Electronics Ltd.

9. 4
CHAPTER 2
COMPANY PROFILE
2.1 COMPANY PROFILE
Bharat Electronics Limited (BEL) is a state-owned electronics company with about nine
factories, and few regional offices in India. It is owned by the Indian Government & primarily
manufactures advanced electronic products for the Indian Armed Forces.BEL is one of the eight
PSUs under Ministry of Defence, Government Of India. It has even earned the government's
Navratna status.
Bharat Electronics Limited (BEL) was set up at Bangalore, India, by the Government of India
under the Ministry of Defence in 1954 to meet the specialised electronic needs of the Indian
defence services. Over the years, it has grown into a multi-product, multi-technology, multi-unit
company serving the needs of customers in diverse fields in India and abroad . BEL is among an
elite group of public sector undertakings which have been conferred the Navratna status by the
Government of India.
The growth and diversification of BEL over the years mirrors the advances in the electronics
technology, with which BEL has kept pace. Starting with the manufacture of a few
communication equipment in 1956, BEL went on to produce Receiving Valves in 1961,
Germanium Semiconductors in 1962 and Radio Transmitters for AIR in 1964. In 1966, BEL set
up a Radar manufacturing facility for the Army and in-house R&D, which has been nurtured
over the years. Manufacture of Transmitting Tubes, Silicon Devices and Integrated Circuits
started in 1967. The PCB manufacturing facility was established in 1968. In 1970, manufacture
of Black & White TV Picture Tube, X-ray Tube and Microwave Tubes started. The following
year, facilities for manufacture of Integrated Circuits and Hybrid Micro Circuits were set up.
1972 saw BEL manufacturing TV Transmitters for Doordarshan. The following year,
manufacture of Frigate Radars for the Navy began. Under the government's policy of
decentralization and due to strategic reasons, BEL ventured to set up new Units at various

10. 5
places. The second Unit of BEL was set up at Ghaziabad in 1974 to manufacture Radars and
Tropo communication equipment for the Indian Air Force. The third Unit was established at
Pune in 1979 to manufacture Image Converter and Image Intensifier Tubes. In 1980, BEL's first
overseas office was set up at New York for procurement of components and materials.
In 1981, a manufacturing facility for Magnesium Manganese Dioxide batteries was set up at the
Pune Unit. The Space Electronic Division was set up at Bangalore to support the satellite
programme in 1982. The same year saw BEL achieve a turnover of Rs.100 crores. In 1983, an
ailing Andhra Scientific Company (ASCO) was taken over by BEL as the fourth manufacturing
Unit at Machilipatnam. In 1985, the fifth Unit was set up in Chennai for supply of Tank
Electronics, with proximity to HVF, Avadi. The sixth Unit was set up at Panchkula the same
year to manufacture Military Communication equipment. 1985 also saw BEL manufacturing on
a large scale Low Power TV Transmitters and TVROs for the expansion of Doordarshan's
coverage.
1986 witnessed the setting up of the seventh Unit at Kotdwara to manufacture Switching
Equipment, the eighth Unit to manufacture TV Glass Shell at Taloja (Navi Mumbai) and the
ninth Unit at Hyderabad to manufacture Electronic Warfare Equipment. In 1987, a separate
Naval Equipment Division was set up at Bangalore to give greater focus to Naval projects. The
first Central Research Laboratory was established at Bangalore in 1988 to focus on futuristic
R&D. 1989 saw the manufacture of Telecom Switching and Transmission Systems as also the
setting up of the Mass Manufacturing Facility in Bangalore and the manufacture of the first batch
of 75,000 Electronic Voting Machines.
The agreement for setting up BEL's first Joint Venture Company, BE DELFT, with M/s Delft of
Holland was signed in 1990. Recently this became a subsidiary of BEL with the exit of the
foreign partner and has been renamed BEL Optronic Devices Limited. The second Central
Research Laboratory was established at Ghaziabad in 1992. The first disinvestment (20%) and
listing of the Company's shares in Bangalore and Mumbai Stock Exchanges took place the same
year. BEL Units obtained ISO 9000 certification in 1993-94. The second disinvestment (4.14%)
took place in 1994. In 1996, BEL achieved Rs.1,000 crores turnover.
In 1997, GE BEL, the Joint Venture Company with M/s GE, USA, was formed. In 1998, BEL

11. 6
set up its second overseas office at Singapore to source components from South East Asia. The
year 2000 saw the Bangalore Unit, which had grown very large, being reorganized into Strategic
Business Units (SBUs). There are seven SBUs in Bangalore Unit. The same year, BEL shares
were listed in the National Stock Exchange. In 2002, BEL became the first defence PSU to get
operational Mini Ratna Category I status. In June 2007, BEL was conferred the prestigious
Navratna status based on its consistent performance.

12. 7
CHAPTER 3
MANUFACTURING UNITS
3.1 MANUFACTURING UNITS
BEL has a total of nine manufacturing complexes spread throughout the nation with Banglore
being the biggest of them. The details about the different manufacturing units of BEL along
with their product specialities are a s follows:-
Sr. No. COMPLEX STATE
1. Ghaziabad Uttar Pradesh
2. Panchkula Haryana
3. Navi Mumabi Maharashtra
4. Kotdwara Uttaranchal
5. Pune Maharashtra
6. Hyderabad Andhra Pradesh
7. Banglore Karnatka
8. Machlipatnam Andhra Pradesh
9. Chennai Tamilnadu
Table 1 : Manufacturing Units

13. 8
Fig. 1: Manufacturing Units
In 1954 with a factory of Jallahali, Bharat Electronics grew into nine units, spread all over India.
The locations & products of the units are given below:-
1. BANGALORE: This is also called BG Complex. Jallahali unit which is the mother unit is
now a part of the BG Complex. This is the biggest unit with approx. 10,000 employees
working here. Among the products here, the important ones are:
Communication equipment
Air & Doordarshan equipment like mobile van for live telecast etc.
Radar-mobile, one dimensional, 3-dimensional & multi-dimensional Radars are

14. 9
manufactured here. Different range of semi-conductor devices like ICs.
Resistors & black & white color TV picture tube glasses.
ISRO‘s requirements are met at space electronics department at Bangalore. Satellite
launch vehicle was also manufactured here.
2. GHAZIABAD: This is the second unit which was set up in 1974, & approx. 2500
employees working here. Radars & some communication equipment are The products
manufactured here are:
 Radars
 SATCOM
 Microwave components
3. PUNE: To diversify further one more branch was added 1979 & this was in Pune. In
this branch around 700-800 employees are working. The product profile includes:
 Image convertor, image intensifier,
 X-ray tubes
 Batteries
 Electro-optics
4. MACHLIPATNAM: There was one Andhra scientific company, which was a sick unit.
This was taken over by BEL & is called ASCO unit in 1983. The products include:
 Optical & optoelectronic equipment like binoculars, microscopes

15. 10
 Medical Electronics
5. NAVI MUMBAI: This is an industrial place near Mumbai. This unit makes:
 Glass shells for black & white TV picture tubes
 Shelters for Electronic Equipment
 Train Actuated Warning System
 Electronic Equipment Assembly
6. PANCHKULA: Panchkula & Kotdwara were proposed simultaneously by the Government
in 1985. It was proposed to set up one unit each in Haryana & Uttar-Pradesh. But the place in
U.P. for setting up a BEL unit could not be decided while that at Haryana was decided &
hence this unit started earlier. This unit manufactures only tactical communication equipment
like VHF, UHF transceivers etc.
7. KOTDWARA: This is a unit in Garhwal district of Uttaranchal. This unit manufactures
radio relay, multiplex equipments & exchanges etc.
8. CHENNAI: The eight unit of BEL was established in Chennai. This unit manufactures:
 Tank related electronic equipments
 Optical fire control systems
9. HYDERABAD: This is another unit of BEL which manufactures electronic warfare
equipments.

16. 11
CHAPTER 4
WAVE SOLDERING
4.1 Introduction:-
Wave soldering is a bulk soldering process used in the manufacture of printed circuit boards.
The circuit board is passed over a pan of molten solder in which a pump produces an upwelling
of solder that looks like a standing wave. As the circuit board makes contact with this wave, the
components become soldered to the board. Wave soldering is used for both through-hole printed
circuit assemblies, and surface mount. In the latter case, the components are glued onto the
surface of a printed circuit board (PCB) by placement equipment, before being run through the
molten solder wave.
As through-hole components have been largely replaced by surface mount components, wave
soldering has been supplanted by reflow soldering methods in many large-scale electronics
applications. However, there is still significant wave soldering where surface-mount technology
(SMT) is not suitable (e.g., large power devices and high pin count connectors), or where simple
through-hole technology prevails (certain major appliances).
Surface Mount Technology (SMT) has brought the electronic industry many benefits. Size and
cost reduction as well as increased in quality and reliability have been demonstrated in numerous
cases. There are many success stories and these are driving the industry in the direction of
greater implementation of SMT every day. The major users of SMT have found that SMT is a
process which can result in continuous improvements in product performance.
Many of the users have reported that product life in the field is increased as a result of a “no
repair” goal in the manufacturing environment. This, of course, does not mean that the product is
discarded if it needs repair. What it does mean is that the process engineer has established a very
achievable goal of “no repair”. The processes are being fine tuned every day, with much of the
feed back coming from the repair station. The repair station is a part of the solder process. In less
focused operations, the solder process and repair areas are two separate processes, but
unfortunately seen as necessary to making the product.

17. 12
4.2 Wave Soldering Process :-
There are many types of wave solder machines; however, the basic components and principles of
these machines are the same. The basic equipment used during the process is a conveyor that
moves the PCB through the different zones, a pan of solder used in the soldering process, a pump
that produces the actual wave, the sprayer for the flux and the preheating pad. The solder is
usually a mixture of metals. A typical solder has the chemical makeup of 50% tin, 49.5% lead,
and 0.5% antimony.
The solvents in use within the wave soldering process are Isopropyalchol (IPA) andSenju Flux.
The use of these two solvents within this process are as follows:
4.2.1 Fluxing:-
Flux in the wave soldering process has a primary and a secondary objective. The primary
objective is to clean the components that are to be soldered, principally any oxide layers that may
have formed. There are two types of flux, corrosive and noncorrosive. Noncorrosive flux
requires precleaning and is used when low acidity is required. Corrosive flux is quick and
requires little precleaning, but has a higher acidity.
Flux is applied to the underside of the Printed Circuit Board (PCB) to aid the wave soldering
process. The purpose of the flux is to remove surface oxides, prevent oxidation of the soldering
pads during the pre-heat and soldering process and improve wettability to ensure a strong low
resistance solder joint.
The PCB travels through the fluxer and solderwave machine on a conveyor. Inside the fluxer
machine there are three spray nozzles that move across the width of the PCB. As the PCB passes
through the fluxer unit the nozzles moves along the width of the PCB and flux is sprayed on the
underside of the PCB.

18. 13
Fig. 2 :PCB Tray Movement
Fig. 3 : Flux Nozzle
The flux is pumped from its original container to a reservoir tank in the fluxer and gravity
fed to the spray nozzles. See picture below.
Cleaning of Flux :- Some types of flux, called "no-clean" fluxes, do not require cleaning; their
residues are benign after the soldering process. Typically no-clean fluxes are especially sensitive
to process conditions, which may make them undesirable in some applications.[ Other kinds of
flux, however, require a cleaning stage, in which the PCB is washed with solventsand
/or deionized water to remove flux residue.

19. 14
Fig 4: ReserviorTank
4.2.2 Isopropylalchol (IPA):-
IPA is used within two processes within the wave soldering process.
1) Cleaning of the pallets which are used to hold the PCB as they pass over the fluxer and wave
soldering machine via conveyors. These pallets are removed from the machine on a daily basis
and are placed into two baths each off which contains approx. 100 litres of IPA. This activity
takes place in a location away from the main building at chemical shed number 7 as per “
Emission and Monitoring/Sampling Points” drawing number 401_3. Approx annual usage of
IPA (909K001) used for this particular cleaning process is 4.8T. This contaminated IPA is then
disposed of as hazardous waste.
2) The remaining annual quantity (approx. 3.7T) of IPA (909K001 & 907K009) is used within
the actual wave soldering production process to ensure that the conveyors on the solderwave
machine are clean and free moving at all times. This material is manually filled into a reservoir
on a daily basis and then pumped into a sub-reservoir that the conveyor passes through allowing
the conveyor chain to be cleaned and free to move. Some small quantities of contaminated IPA
will remain within the reservoir and sub-reservoirs and is removed as hazardous waste.

20. 15
Fig. 5: IPA Reservoir
Fig. 6 : Conveyor
4.2.3 Preheating :-
Preheating helps to accelerate the soldering process and to prevent thermal shock. The purpose
of the preheat and flux zones is to prepare the PCB assembly for soldering. To maximize
reaching the established goals, the flux should prepare the terminations and PCB solder pads for
the solder. RMA type fluxes are adequate. If the PCB or the parts do not demonstrate good
solder wetting characteristics, the supplier of these need to improve the solderability.
Concentrated efforts with the suppliers in improving solderability can pay large dividends.

21. 16
The solder wave equipment manufacturers have recognized the importance of preheat and have
included individually controlled bottom side and top side preheat zones with individually
controlled heaters to reduce the gradual nature of the heating zones.
The goals of the process profile in the preheat zone are numerous.:-
A. The heating should be gradual and not exceed 2°C per second. Higher heating rates have
the potential of increasing the temperature differential across the board, which can increase the
amount of warp and twist (and possibly local delaminations) in the board as it exceeds the glass
transition temperature.
B. The heating should be somewhat uniform on the top and bottom side of the board.
During the preheat, the reflow solder side of the board must by necessity be kept a little lower
than the wave solder side, however, top side preheat will increase the uniformity of wave solder
preheat, and will decrease the temperature gradients the PCB is subjected to.
C. The heating should be in line with the needs of the fluxes. No clean fluxes may demand a
little more preheat. Excessive preheat should not be used.
D. The preheat should be uniform across the boards, and not be subject to board loading
and environmental conditions. The preheat zones of most wave solder machines are infrared
heating zones. Uniformity of heating is improving as more and more zones are being added to
the wave solder. However, most users have not applied the same care to the preheat zones of
wave solder equipment as they have to the reflow solder equipment themselves. Typical
problems seen with wave solder equipment preheat zones are usually as a result of the openness
of the throat and the equipment itself, and the environment the machine has been placed in. The
profile is typically established under ideal one board conditions. Then in production numerous
board loading configurations are run, resulting in excessive and different load conditions on the
preheaters.

22. 17
Profiling under all conditions is suggested. A considerably worse situation can be encountered.
The environment around the wave solder equipment is normally very warm and uncomfortable.
Venting is added, air conditioning is sometimes made available, and doors to the room are
opened to make the environment more tolerable. All this variable cooling air is typically drawn
into the preheat zone through the bottom of the machine or the throat of the machine. Vents for
fumes accelerate this cooling tunnel. These have very large effects on the control and variability
of the profile, and can result in very large thermal stresses as the part leaves the solder wave.
Shadowing of the preheaters also can result in differentials of preheat across the board. It is
suggested that profiles be run with thermocouples in numerous locations across the board.
Shadowing can result from large components being placed near smaller components, tooling and
fixturing proximity, etc.
E. The temperature differential between the preheat and the wave solder peak should not
exceed 120°C. Of course, less is better. Some of the largest benefits in reduction of thermal
stresses can be achieved in the preheat zone. This recommendation is higher than that normally
given by ceramic chip capacitor suppliers. See notes under “Conclusions”. Some of the results
seen with higher thermal stresses are:
• increased solder fillet sizes
• increased solder bridging
• increased amounts of solder balls
• increased amounts of solder peaking
• increased failures of thermal stress sensitive parts such as ceramic chip capacitors
Trapsto be Avoided
• Preheating from one side only
• Counting on controllers which measure heater temperature
• Establishing the profile under ideal conditions

23. 18
• Using the same profile for all assemblies
• Using solder wave equipment which was designed for through hole soldering, and not having
adequate preheat zones.
• Large gaps between preheat and solder wave which result in large temperature drops.
Attention to the profiles as seen in the preheat zone, and then monitoring the important
parameters
Fig. 7: Wave Soldering (Through Hole Only)
Fig. 8 : Reflow Profile (Surface Mount Only)

24. 19
4.2.4 Solder Bath/Pot :-
The box containing the solder is called the solder bath, which has the capacity of 400kg. The
temperature of the solder bath is 250 – 270 degree Celsius. While the solder is heated up inside
the solder bath, the pump arrangement provides for the hot solder to flow. The solder nozzle then
produces a solder wave. After the solder bath, the conveyor belt is set on the angle of 4 – 7
degrees.
Different combinations of tin, lead and other metals are used to create solder. The combinations
used depend on the desired properties. The most popular combination is 63% tin, 37% lead. This
combination is strong, has a low melting range, and melts and sets quickly. Higher tin
compositions gives the solder higher corrosion resistances, but raises the melting point. Another
common composition is 11% tin, 37% lead, 42% bismuth, and 10% cadmium. This combination
has a low melting point and is useful for soldering components that are sensitive to heat
Fig. 9 Solder Bath/Pot
4.2.5 Solder Wave Zone :-
Most SMT solder wave equipment now have dual zones. The first zone is more agitated to
increase the wetting action of the solder, and the second zone is usually a smoothing zone to
optimize the shape of the fillet and reduce bridging. Some of the waves are separated and some
are adjoining each other in the equipment.

25. 20
As the PCB leaves the preheat zone and enters the solder wave zone, large temperature gradients
are established across the board. The differences in expansion establish twist, bow, bend, and
numerous other stresses across the assembly. These stresses are magnified for thinner boards,
and for large panels of multiple boards which have been pre-routed for separation. Adequate
fixturing and tooling is necessary to keep these stresses to a minimum.
The goalsfor the wavezone are:
A. The peak temperature of the wave solder should be kept to a minimum. Some tests have
shown that reduction of thermal stress between preheat and the wave solder is better
accomplished by reduction of the peak wave temperature (as opposed to increasing the preheat
temperature). A good goal is a peak wave solder temperature of 235°C. With this a peak preheat
temperature of 115°C is allowable, and the temperature does not exceed the glass transition
temperature of the board material. Wave solder peak temperatures of 250°C are common,
however, this requires larger preheat temperatures, and typically results in more stress to the
PCB.
B. Time in the wave should be kept to a minimum. Typical times in the total solder wave are 5
to 8 seconds. Time in the wave exceeding 10 seconds can begin to have detrimental effects on
the solder ability of the parts and the board, result in breakdown of the fluxes making cleaning
more difficult, and greatly magnify the stresses applied to the board.
C. Temperature between the waves should be maintained above the liquidus points. Some
equipment have gaps between the two waves, and with improper venting and room
environments, the solder temperature can go below the solidus temperature, and then be
subjected to another thermal stress in the second wave. This also will defeat the purpose of the
second wave, and greatly diminish the effect of “air knives” if they are used.

26. 21
Fig. 10 : Solder Wave Zone
Trapsto be Avoided :-
• Increasing wave temperature to improve solderability
• Increasing time in wave to improve solderability
• Increasing temperatures to reduce solder balls, bridges, skips, etc.
• Establishing wave profiles once, and not monitoring frequently
• Adding forced air cooling directly after wave solder
• Using fixturing which adds stress to the boards
• Convey or transfer systems which drop boards or introduce the possibility of twisting boards
by mechanical jamming in the conveyor.

27. 22
4.2.6 Hot Air Debridging:-
The concept of using hot air blowing on the solder joints immediately after the wave to minimize
bridging and solder fillet size, is an excellent idea. The air temperature immediately at the exit of
the orifice is typically set near 275°C, and the impinging air on the part/board assembly is
typically less than 230°C. This concept was developed with SMT assemblies in mind, and has
been shown to be an excellent improvement.
4.2.7 Cooling Zone:-
It is important that the PCBs be allowed to cool at a reasonable rate. If they are cooled too fast,
then the PCB can become warped and the solder can be compromised. On the other hand, if the
PCB is allowed to cool too slowly, then the PCB can become brittle and some components may
be damaged by heat. The PCB should be cooled by either a fine water spray or air cooled to
decrease the amount of damage to the board.
After the board assembly leaves the solder wave and the hot air debridging area, it enters a very
critical area. It is very important to let the stresses applied by the large heat and mechanical
warp, twist, and expansion differences relieve themselves in a natural slow manner. Some very
recent data indicates that thermal shock stresses applied by cooling after the wave can be more
detrimental than that applied by the heat stress of the wave itself.
The process engineer might have a tendency to supply forced air cooling directly after the wave
solder and hot air debridging areas. Some wave solder equipment is being supplied with fans and
some even have “CHILLER” zones. There are multiple reasons given for this attempt at cooling.
One is that the board needs to be cooled for people to handle it. Another is that the fans are there
and are turned on without reason.
Both of these are not valid technically and need further consideration. Another reason is that the
solder needs to be cooled rapidly to establish fine grain solder fillets (represented by nice “shiny”
solder joints).

28. 23
While cooling can help this, it has been shown that the fine grain structure achieved this way is
only temporary. The stresses set up in the solder fillet and the board are relieved in less than 24
hours at room temperature and the solder structure begins to coarsen. Fatigue testing of various
solder joints have shown that the perceived advantage of shiny joints is not proven out.
Other sources of excessive thermal stresses can be found to be applied by:
• large heatsinks on the top side of the board which have not reached high temperatures during
the process
• excessive venting of the wave solder machine directly after or above the wave zone.
• room air inlets under the wave solder machine or through the exit and input throats of the
machine.
Air conditioned or winter air rushing through the machine can cause very stressful profiles.

29. 24
CHAPTER 5
WAVE SOLDERING MACHINES
5.1 Different types of Wave Soldering Machines :-
There are different varieties of machine for wave soldering. Here the internal structure and some
machines are depicted in figures.
Fig. 11 : A simple wave soldering machine

30. 25
Fig. 12 : A new and fully automated wave soldering machine.
Fig. 13 Wave Soldering machine(Automated Lead Free) operated by a operator

31. 26
Fig. 14 Internal Structure and different zones of Wave Soldering machine.

32. 27
CONCLUSION
The six weeks of summer training at BEL, KOTDWARA unit generated a lot more interest in
my subject.
It made me more aware of the scope of Electronics & Communication Engineering. It has also
made me appreciative of an industrial work environment.
Undergoing training on the indoor substation has helped me integrate conceptual knowledge with
real life application. I was fortunate to have personal guidance from experienced professionals
who took been interest in explaining the working details of various equipments.
I feel that without this opportunity, my own understanding of this subject and also the motivation
to acquire more knowledge would have remained incomplete.
Well, regarding future scope I think my training has given me enough motivation and an
exposure that I will try to join defence services or get linked up with the defence of the country.
“To know the technical know-how, industrial training is the best way to move forward.”

33. 28
REFERENCES
[1] THE MAIN RESOURCES OF THE WORK WERE THE FACULTY OF HRD
DEPARTMENT.
[2] WEBSITE:
 http://www.bel-india.com/
 https://en.wikipedia.org/wiki/Wave_soldering
 http://www.kemet.com/