Manual Workshop

A C Patil College of Engineering, Kharghar, Electronics Department

Electronics Workshop I/ Lab Manual/ SEM IV Page 1

Jawahar Education Societys

A C Patil College of Engineering, Kharghar

Electronics Department

Electronics Workshop I

Lab Manual for SEM IV



Jawahar Education societys

A C Patil College of Engineering, Kharghar, Navi Mumbai

Electronics Department

ELECTRONICS WORKSHOP I

LIST OF EXPERIMENTS

Class: SE Sem: IV

1) Study of soldering techniques

2) Study of PCB techniques

3) Hardware project

a. Experiment based (BEC, ECAD, LICD, ENAS)

b. Application based (IC 741 Op-Amp, IC 555 Timer etc)

4) Software based project

a. Experiments/Application based DSD I & DSD II.



Experiment No 1

Aim :

To study the soldering techniques.

Objective :

To understand soldering techniques, components used for soldering.

Theory :

Soldering is a process in which two or more metal items are joined together by melting and

flowing a filler metal (solder) into the joint, the filler metal having a lower melting point than the

workpiece. Soldering differs from welding in that soldering does not involve melting the work

pieces. In brazing, the filler metal melts at a higher temperature, but the workpiece metal does

not melt. Formerly nearly all solders contained lead, but environmental concerns have

increasingly dictated use of lead-free alloys for electronics and plumbing purposes.

Origin:

There is evidence that soldering was employed up to 5000 years ago in MesopotamiaSoldering

and brazing are thought to have arisen very early in the history of metal-working, probably

before 4000 BCE. Sumerian swords from ~3000 BCE were assembled using hard soldering.

Soldering was historically used to make jewelry items, cooking ware and tools, as well as other

uses such as in assembling stained glass.

Applications:

Soldering is used in plumbing, in electronics and metalwork from flashing to jewelry.

Soldering provides reasonably permanent but reversible connections between copper pipes

in plumbing systems as well as joints in sheet metal objects such as food cans, roof flashing, rain

gutters and automobile radiators.

Jewelry components, machine tools and some refrigeration and plumbing components are often

assembled and repaired by the higher temperature silver soldering process. Small mechanical

parts are often soldered or brazed as well. Soldering is also used to join lead came and copper

foil in stained glass work. It can also be used as a semi-permanent patch for a leak in a container

or cooking vessel.

Electronic soldering connects electrical wiring and electronic components to printed circuit

boards (PCBs).



Components used for Soldering:

1. Solder

2. Solder gun

3. Flux

1. Solder

Solder is a fusible metal alloyused to join together metal workpieces and having a melting point

below that of the workpiece

Soft solder is typically thought of when solder or soldering is mentioned, with a typical melting

range of 90 to 450 C (190 to 840 F It is commonly used inelectronics and plumbing, and when

manually applied is often done so using a soldering ironor soldering gun. Alloys that melt

between 180 and 190 C (360 and 370 F) are the most commonly used. Soldering performed

using alloys with melting point above 450 C (840 F)is called 'hard soldering', 'silver soldering',

or brazing.

For certain proportions an alloy becomes eutectic and melts at a single temperature; non-eutectic

alloys have markedly different solidus and liquidus temperature, and within that range they exist

as a paste of solid particles in a melt of the lower-melting phase. In electrical work, if the joint is

disturbed in the pasty state before it has solidified totally, a poor electrical connection may result;

use of eutectic solder reduces this problem. The pasty state of a non-eutectic solder can be

exploited in plumbing as it allows molding of the solder during cooling, e.g. for ensuring

watertight joint of pipes, resulting in a so-called 'wiped joint'.

For electrical and electronics work solder wire is available in a range of thicknesses for hand-

soldering, and with cores containing flux. It is also available as a paste or as a preformed foil

shaped to match the workpiece, more suitable for mechanized mass-production. Alloys of lead

and tin were universally used in the past, and are still available; they are particularly convenient

for hand-soldering. Lead-free solder, somewhat less convenient for hand-soldering, is often used

to avoid the environmental effect of lead.

Plumbers often use bars of solder, much thicker than the wire used for electrical

applications. Jewelers often use solder in thin sheets which they cut into snippets.

With the reduction of the size of circuit board features, the size of interconnects shrinks as well.

Current densities above 104 A/cm

2 are often achieved and electromigration becomes a concern.

At such current densities the Sn63Pb37 solder balls form hillocks on the anode side and voids on

the cathode side; the increased content of lead on the anode side suggests lead is the primary

migrating species.

Types of Solders

1.1 Lead Solder:

1.2 Lead free solder



1.3 Flux core solder

1.4 Hard Solder

1.1 Lead solder :

Tin/lead solders, also called soft solders, are commercially available with tin concentrations

between 5% and 70% by weight.

solder

The greater the tin concentration, the greater the solderstensile and shear strengths. Alloys

commonly used for electrical soldering are 60/40 Tin/lead (Sn/Pb) which melts at 370 F or

188 C and 63/37 Sn/Pb used principally in electrical/electronic work. The 63/37 is

a eutectic alloy, which:

1. has the lowest melting point (183 C or 361.4 F) of all the tin/lead alloys; and

2. the melting point is truly a point not a range.

In plumbing, a higher proportion of lead was used, commonly 50/50. This had the advantage of

making the alloy solidify more slowly, so that it could be wiped over the joint to ensure

watertightness, the pipes being physically fitted together before soldering. Although lead water

pipes were displaced by copper when the significance of lead poisoning began to be fully

appreciated, lead solder was still used until the 1980s because it was thought that the amount of

lead that could leach into water from the solder was negligible from a properly soldered joint.

The electrochemical couple of copper and lead promotes corrosion of the lead and tin, however

tin is protected by insoluble oxide. Since even small amounts of lead have been found

detrimental to health,Lead in plumbing solder was replaced by silver (food grade applications)

or antimony, with copper often added, and the proportion of tin was increased The addition of

tinmore expensive than leadimproves wetting properties of the alloy; lead itself has poor

wetting characteristics. High-tin tin-lead alloys have limited use as the workability range can be

provided by a cheaper high-lead alloy.

In electronics, components on printed circuit boards (PCBs) are connected to the printed circuit,

and hence to other components, by soldered joints. For miniaturized PCB joints with surface

mount components, solder paste has largely replaced solid solder.

Lead-tin solders readily dissolve gold plating and form brittle intermetallics

Sn60Pb40 solder oxidizes on the surface, forming a complex 4-layer structure: tin(IV) oxide on

the surface, below it a layer of tin(II) oxide with finely dispersed lead, followed by a layer of



tin(II) oxide with finely dispersed tin and lead, and the solder alloy itself underneath. Lead, and

to some degree tin, as used in solder contains small but significant amounts

of radioisotope impurities. Radioisotopes undergoing alpha decay are a concern due to their

tendency to cause soft errors. Polonium-210 is especially problematic; lead-210beta

decays to bismuth-210 which then beta decays to polonium-210, an intense emitter of alpha

particles. Uranium-238 and thorium-232 are other significant contaminants of alloys of lead

1.2 Lead Free Solder:

Pure tin solder wire

Soldering copper pipes using a propane torch and lead-free solder

. Lead-free solders in commercial use may contain tin, copper, silver, bismuth,indium, zinc,

antimony, and traces of other metals. Most lead-free replacements for conventional Sn60/Pb40

and Sn63/Pb37 solder have melting points from 5 to 20 C higher, though solders with much

lower melting points are available.

Drop-in replacements for silkscreen with solder paste soldering operations are available. Minor

modification to the solder pots (e.g. titanium liners or impellers) used in wave-soldering

operations may be desired to reduce maintenance costs associated with the increased tin-

scavenging effects of high tin solders. Since the properties of lead-free solders are not as

thoroughly known, they may therefore be considered less desirable for critical applications, like

certain aerospace or medical projects. "Tin whiskers" were a problem with early electronic

solders, and lead was initially added to the alloy in part to eliminate them.

(Tin-Silver-Copper) solders are used by two thirds of Japanese manufacturers for reflow

and wave soldering, and by about 75% of companies for hand soldering. The widespread use of

this popular lead-free solder alloy family is based on the reduced melting point of the Sn-Ag-Cu

ternary eutectic behavior (217 C), which is below the Sn-3.5Ag (wt.%) eutectic of 221 C and

the Sn-0.7Cu eutectic of 227 C (recently revised by P. Snugovsky to Sn-0.9Cu). The ternary

eutectic behavior of Sn-Ag-Cu and its application for electronics assembly was discovered (and



patented) by a team of researchers from Ames Laboratory, Iowa State University, and

from Sandia National Laboratories-Albuquerque.

Tin-based solders readily dissolve gold, forming brittle intermetallics; for Sn-Pb alloys the

critical concentration of gold to embrittle the joint is about 4%. Indium-rich solders (usually

indium-lead) are more suitable for soldering thicker gold layer as the dissolution rate of gold in

indium is much slower. Tin-rich solders also readily dissolve silver; for soldering silver

metallization or surfaces, alloys with addition of silvers are suitable; tin-free alloys are also a

choice, though their wettability is poorer. If the soldering time is long enough to form the

intermetallics, the tin surface of a joint soldered to gold is very dull.

1.3 Flux Core Solder:

Electrical solder with an integrated rosin core, visible as a dark spot in the cut end of the solder

wire.

Flux is a reducing agent designed to help reduce (return oxidized metals to their metallic state)

metal oxides at the points of contact to improve the electrical connection and mechanical

strength. The two principal types of flux are acid flux, used for metal mending and plumbing,

and rosin flux, used in electronics, where the corrosiveness of acid flux and vapors released

when solder is heated would risk damaging delicate circuitry.

Due to concerns over atmospheric pollution and hazardous waste disposal, the electronics

industry has been gradually shifting from rosin flux to water-soluble flux, which can be removed

with deionized water and detergent, instead of hydrocarbon solvents.

In contrast to using traditional bars or coiled wires of all-metal solder and manually applying

flux to the parts being joined, some light hand soldering since the mid-20th century has used

flux-core solder. This is manufactured as a coiled wire of solder, with one or more continuous

bodies of non-acid flux embedded lengthwise inside it. As the solder melts onto the joint, it frees

the flux and releases that on it as well.

1.4 Hard Solder:

Hard solders are used for brazing, and melt at higher temperatures. Alloys of copper with

either zinc or silver are the most common.

In silversmithing or jewelry making, special hard solders are used that will pass away assay.

They contain a high proportion of the metal being soldered and lead is not used in these alloys.

These solders vary in hardness, designated as "enameling", "hard", "medium" and



"easy". Enameling solder has a high melting point, close to that of the material itself, to prevent

the joint desolderingduring firing in the enameling process. The remaining solder types are used

in decreasing order of hardness during the process of making an item, to prevent a previously

soldered seam or joint desoldering while additional sites are soldered. Easy solder is also often

used for repair work for the same reason. Flux or rouge is also used to prevent joints from

desoldering.

Silver solder is also used in manufacturing to join metal parts that cannot be welded. The alloys

used for these purposes contain a high proportion of silver (up to 40%), and may also

contain cadmium.

2. Soldering iron

A soldering iron is a hand tool used in soldering. It supplies heat to melt the solder so that it can

flow into the joint between two workpieces.

A soldering iron is composed of a heated metal tip and an insulated handle. Heating is often

achieved electrically, by passing an electric current (supplied through an electrical cord or

battery cables) through a resistive heating element. Portable irons can be heated by combustion

of gas stored in a small tank, often using a catalytic heater rather than a flame. Simple irons less

commonly used than in the past were simply a large copper bit on a handle, heated in a flame.

Soldering irons are most often used for installation, repairs, and limited production work in

electronics assembly. High-volume production lines use other soldering methods.[1]

Large irons

may be used for soldering joints in sheet metal objects. Less common uses

includepyrography (burning designs into wood) and plastic welding.



Types

Soldering iron in use

2.1 Simple iron

For electrical and electronics work, a low-power iron, a power rating between 15 and 35 watts, is

used. Higher ratings are available, but do not run at higher temperature; instead there is more

heat available for making soldered connections to things with large thermal capacity, for

example, a metal chassis. Some irons are temperature-controlled, running at a fixed temperature

in the same way as a soldering station, with higher power available for joints with large heat

capacity. Simple irons run at an uncontrolled temperature determined by thermal equilibrium;

when heating something large their temperature drops a little, possibly too much to melt solder.

2.2 Portable iron

Small irons heated by a battery, or by combustion of a gas such as butane in a small self-

contained tank, can be used when electricity is unavailable or cordless operation is required. The

operating temperature of these irons is not regulated directly; gas irons may change power by

adjusting gas flow.

2.3 Temperature-controlled soldering iron

Simple irons reach a temperature determined by thermal equilibrium, dependent upon power

input and cooling by the environment and the materials it comes into contact with. The iron

temperature will drop when in contact with a large mass of metal such as a chassis; a small iron

will lose too much temperature to solder a large connection. More advanced irons for use in

electronics have a mechanism with a temperature sensor and method of temperature control to

keep the tip temperature steady; more power is available if a connection is large. Temperature-

controlled irons may be free-standing, or may comprise a head with heating element and tip,

controlled by a base called a soldering station, with control circuitry and temperature adjustment

and sometimes display.

A variety of means are used to control temperature. The simplest of these is a variable power

control, much like a light dimmer, which changes the equilibrium temperature of the iron without

automatically measuring or regulating the temperature. Another type of system uses a thermostat,



often inside the iron's tip, which automatically switches power on and off to the element. A

thermal sensor such as a thermocouple may be used in conjunction with circuitry to monitor the

temperature of the tip and adjust power delivered to the heating element to maintain a desired

temperature.

Another approach is to use magnetized soldering tips which lose their magnetic properties at a

specific temperature, the Curie point. As long as the tip is magnetic, it closes a switch to supply

power to the heating element. When it exceeds the design temperature it opens the contacts,

cooling until the temperature drops enough to restore magnetisation. More complex Curie-point

irons circulate a high-frequency AC current through the tip, using magnetic physics to direct

heating only where the surface of the tip drops below the Curie point

3. Soldering Gun

A soldering gun is an approximately pistol-shaped tool for soldering metals using tin-

based solder to achieve a strong mechanical bond with good electrical contact. The tool has a

trigger-style switch so it can be easily operated with one hand. The body of the tool contains a

transformer with a primary winding connected to mains electricity when the trigger is pressed,

and a single-turn secondary winding of thick copper with very low resistance. A soldering tip,

made of a loop of thinner copper wire, is secured to the end of the transformer secondary by

screws, completing the secondary circuit. When the primary of the transformer is energized,

several hundred amperes of current flow through the secondary and very rapidly heat the copper

tip. Since the tip has a much higher resistance than the rest of the tubular copper winding, the tip

gets very hot while the remainder of the secondary warms much less. A tap on the primary

winding is often used to light a pilot lamp which also lights the workpiece.

The soldering gun is useful when soldered joints must be made intermittently. A constant-heat

device has to be set in a safe place when powered but not actually in use, to prevent damage or

injury. The fast-switching gun cools quickly enough to be set down a few seconds after use.

4. Flux:

Rosin Used As Flux For Soldering



The purpose of flux is to facilitate the soldering process. One of the obstacles to a successful

solder joint is an impurity at the site of the joint, for example, dirt, oil or oxidation. The

impurities can be removed by mechanical cleaning or by chemical means, but the elevated

temperatures required to melt the filler metal (the solder) encourages the work piece (and the

solder) to re-oxidize. This effect is accelerated as the soldering temperatures increase and can

completely prevent the solder from joining to the workpiece. One of the earliest forms of flux

was charcoal, which acts as a reducing agent and helps prevent oxidation during the soldering

process. Some fluxes go beyond the simple prevention of oxidation and also provide some form

of chemical cleaning (corrosion).

For many years, the most common type of flux used in electronics (soft soldering) was rosin-

based, using the rosin from selected pine trees. It was ideal in that it was non-corrosive and non-

conductive at normal temperatures but became mildly reactive (corrosive) at the elevated

soldering temperatures. Plumbing and automotive applications, among others, typically use an

acid-based (muriatic acid) flux which provides cleaning of the joint. These fluxes cannot be used

in electronics because they are conductive and because they will eventually dissolve the small

diameter wires. Many fluxes also act as a wetting agent in the soldering process, reducing

the surface tension of the molten solder and causing it to flow and wet the workpieces more

easily.

Fluxes for soft solder are currently available in three basic formulations:

1. Water-soluble fluxes - higher activity fluxes designed to be removed with water after

soldering (no VOCs required for removal).

2. No-clean fluxes - mild enough to not "require" removal due to their non-conductive and

non-corrosive residue. These fluxes are called "no-clean" because the residue left after

the solder operation is non-conductive and won't cause electrical shorts; nevertheless

they leave a plainly visible white residue that resembles diluted bird-droppings. Because

discernible flux residue on circuit boards is a defect for all three classes of electronic

circuit boards (ranging from cheap consumer electronics to high-reliability, mission

critical applications), this application requires cleaning of these fluxes as well. (Typically

brushing with 99% isopropyl alcohol as the solvent and wiping with lint-free non-

synthetic (e.g., cotton) wipes.)

3. Traditional rosin fluxes - available in non-activated (R), mildly activated (RMA) and

activated (RA) formulations. RA and RMA fluxes contain rosin combined with an

activating agent, typically an acid, which increases the wettability of metals to which it is

applied by removing existing oxides. The residue resulting from the use of RA flux

is corrosive and must be cleaned. RMA flux is formulated to result in a residue which is

not significantly corrosive, with cleaning being preferred but optional.

Flux performance needs to be carefully evaluated; a very mild 'no-clean' flux might be perfectly

acceptable for production equipment, but not give adequate performance for a poorly controlled

hand-soldering operation.



Experiment No 2

Aim :

Study of PCB techniques.

Objective :

To understand different type of techniques and how to make PCB

Theory:

A printed circuit board, or PCB, is used to mechanically support and electrically

connect electronic components using conductive pathways, tracks or signal

traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to

as printed wiring board(PWB) or etched wiring board. Printed circuit boards are used in virtually

all but the simplest commercially produced electronic devices.

A PCB populated with electronic components is called a printed circuit assembly (PCA), printed

circuit board assembly or PCB Assembly(PCBA)

Types of Printed Circuit Boards

Single Sided Board

This is the least complex of the Printed Circuit Boards, since there is only a single layer of

substrate. All electrical parts and components are fixed on one side and copper traces are on the

other side. Single-sided PCB means that wiring is available only on one side of the insulating

substrate. The side which contains the circuit pattern is called the solder side whereas the other

side is called the component side. These types of boards are mostly used in case of simple

circuitry and where the manufacturing costs are to be kept at a minimum. Nevertheless, they

represent a large volume of printed boards currently produced for professional and non-

professional grades.



The single-sided boards are manufactured mostly by the print and etch method or by the diecut

technique by using a die that carries an image of the wiring pattern; and the die is either

photoengraved or machine-engraved. Normally, components are used to jump over conductor

tracks, but if this is not possible, jumper wires are used. The number of jumper wires on a board

cannot be accepted beyond a small number because of economic reasons, resulting in the

requirement for double-sided boards.

Double Sided Board

This is the most common type of board, where parts and components are attached to both sides

of the substrate. In such cases, double-sided PCBs that have connecting traces on both the sides

are used. Double-sided Printed Circuit Boards usually use through-hole construction for

assembly of components.

With two-sided boards, traces can now cross over each other, increasing density without point-

to-point soldering.

The Double Sided Printed Circuit Board that we offer are individual PCB that are stepped up

onto a bigger panel, tooled with fiducial marks to assist assembly and and are bridged (using

break out pips) or scored so boards can be freed from the panel. It allows many PCB to be

manufactured at once and also means many PCB can be assembled together that reduces the

process time

The double sided printed circuit boards are available in various technical specifications and some

of them are:



Hot air solder leveling tin lead

Companies exempt from rohs regulations

Electro less nickel

Immersion gold

Immersion tin

Surface coatings

Photo image able solder resist in various colors (green, red, blue)

Various colors (white, black, yellow)

Component notation (silk screen legend) two pack epoxy ink

Multi Layered Board

Multi layered PCB consists of several layers of substrate separated by insulation. Most common

multilayer boards are: 4 layers, 6 layers, 8 layers, and 10 layers. However, the total number of

layers that can be manufactured can exceed over 42 layers. These types of boards are used in

extremely complex electronic circuits.

To increase the area available for the wiring even more these boards have one or more conductor

pattern inside the board. This is achieved by gluing (laminating) several double-sided boards

together with insulating layers in between. The number of layers is referred to as the number of

separate conductor patterns. It is usually even and includes the two outer layers. Most main

boards have between 4 and 8 layers, but PCBs with almost 100 layers can be made. Large super



computers often contain boards with extremely many layers, but since it is becoming more

efficient to replace such computers with clusters of ordinary PCs, PCBs with a very high layer

count are less and less used. Since the layers in a PCB are laminated together it is often difficult

to actually tell how many there are, but if you inspect the side of the board closely you might be

able count them.

The vias described in the section about double-sided PCBs always penetrate the whole board.

When there are multiple layers of conductor patterns, and you only want to connect some of

them, such vias waste space that could be used to route other wires. 'Buried ' and 'Blind ' vias

avoid this problem because they only penetrate as many layers as necessary. Blind vias connect

one or more of the inner layers with one of the surface layers without penetrating the whole

board. Buried vias only connect inner layers. It is therefore not possible so see such vias by just

looking at the surface of the PCB.In multi-layer PCBs whole layers are almost always dedicated

to Ground and Power. We therefore classify the layers as Signal, Power or Ground planes.

Sometimes there is more than one of both Power and Ground planes, especially if the different

components on the PCB require different supply voltages.



PCB MANUFACTURING PROCESS:

INSTRUCTION:

Use clamper for handling PCB in the lab as etching solution is dangerous to skin.

1) Get the printout of the artwork on transparent sheet that is artwork film.

2) Clean the copper side of the PCB uing steel wool.

3) Use dip coationg machine:

a. Place the PCB in the clamper attached to the machine and dip the PCB in

photoresist using up/down switch.

4) Use of Oven:

a. Place the PCB in the oven at 50oC for 5 minutes to dry.

5) Use of ultraviolet exposure unit:

a. Place the artwork film inside (front side downward) and copper side of PCB

downward above the film.

b. Expose PCB to UV exposure for 2.5 minutes.

6) Using the clamper place the PCB in the developer for 1.25 minutes and wash the PCB

with water.

7) Dip the PCB into the photoresist dye solution to get the coloured tracks.

8) Wash the PCB with water and and clean the PCB using steel wool.

9) Use of shearing machine:

a. Use the shearing machine to cut the unwanted PCB

10) Use of drilling:

a. PCB is ready for drilling.(1mm for components)



PCB Making Procedure

Students are required to follow steps for making PCB layout.

Step 1) Make neat and complete circuit diagram of the project .

Use any circuit maker otherwise use LiveWire .

For example

Inverting Amplifier :

Figure shows the circuit diagram of Inverting Amplifier using 741op-amp.

Step 2) To get the print of layout on PCB follow the steps given below:

a. Open your complete circuit diagram in Livewire software which helps us to get the layout for

PCB.

b. Then on the GUI(front panel) of Live wire software go to Tools then click on the option

convert to Design to Printed Circuit Board. As shown in the figure below.



C. Here Click on option as shown in above figure and then click on Next button.



d. After doing above procedure the other software called PCB Wizard will get open

automatically



If you are able to get above message on PCB Wizard software , then circuit layout is completed and

correct.

Real World

Unpopulated



Solder Side Artwork

Finally after making PCB mount your components and solder it carefully.

Then do testing and see the result.

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