INDUSTRIAL TRAINING AT

Based On

Double Sided Plated Through Hole Printed Circuit Boards.

PRINTED CIRCUIT BOARDS

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

electronic component using conductive pathways.

It is simply a plate made up of dielectric material with very thin layer of copper on it.

The thickness of dielectric material(BASE) of PCB vary from .6 to 3.5 mm and thickness

of Copper layer is between 17 to 35 micron

NEED OF PCB

Every electronic component has wire leads and PCB has holes drilled for mechanical

support and electronic connection of each wire of every component.

These components' leads are then passed through the holes and soldered to the PCB

trace. Which makes electrical connection of components with Conductive Pathways.

DISADVANTAGE OF SINGLE SIDED PCB In Single Sided PCB’s Components are connected to each other via copper tracks at one

side, While Components are mounted on another side. In Single Sided PCBs we can’t mount components on both sides. Which Results in BIG Circuit Boards as Shown…

EVOLUTION OF DOUBLE SIDED BOARDS As Single Sided PCBs fails on large Space Requirement, Then Double Sided PCBs has

came into Practice.

Now, We can place Components as well as Current Pathways on both sides.

But we have to make electrical connection With Jumper (a wire) which may

disconnected from circuit under certain Circumstances.

PTH BOARDS

Metallization of holes by copper plating has been practiced instead of Jumper in 1950s.

Since PWB substrate is an insulating material, and therefore nonconductive, holes must

be metallized first before subsequent copper plating can take place.

The usual metallization procedure is to catalyze the holes with palladium catalyst

followed by electroless

copper plating.

STEPS FOR PCB MAKING

Design Formation

Base Material Selection

Electro less Process

Screen Printing

Etching

Solder Masking

HAL

BBT

PCB DESIGN MAKING

Design and layout broadly includes the perspective of total system

hardware, which includes not only the printed circuit but each and

every component in its final form.

Which Includes Board size, Number of layers, Pad stack sizes, Hole

sizes, Layer thickness, Board thickness, Supply and ground layer

thickness and Component details with specifications

Factors that Vary Design are:-

Resistance & Conductor Dimensioning.

Electromagnetics.

Ground Considration.

SCHEMATIC CAPTURE

Draw Circuit as it is in computer or graph.

Analyze it.

You should have Correct Dimension Footprint of every Component in

Layout Plus also.

FORWARD ANNOTATION

Now we have to forward annotate the circuit into Layout Plus.

This Converts Schematic Components into Layout Foot Prints.

Now we have Components with Net List.

Net list is an Special Feature by which we can detect which pin of an component is

connected to another pin

of Component.

MANUAL CONNECTION & AUTOROUTING

Now, our next step is to Inter Connect Components with each other as per NETLIST.

One can also do this by AutoRouting.

You can start the autorouter by selecting Autoroute → Board from the menu bar. The

autorouter will begin routing the board.

DESIGNED PCB

3D VIEW

With 3d View we can check it out whether the physical appearance of any component may or may not overlap each other.

BASE MATERIAL

FR(Flame Retardent)-1, the most rarely used PCB material. In which paper and phenol is used as laminate material.

FR-2, FR-3, with Combination of Paper-Epoxy FR-4, with glass-epoxy as laminate material. It is the most common PCB material.

STEP -1 SHEARING

When copper-clad laminates are to be sheared, the shear should be set with adequate

Spacing between them.

Now we have to add some dimensions in design size as margin. Using margin has a

safety measure to protect the corners from any type of damage during processing.

STEP-2 DRILLING

Usually we Drill holes with the help of CNC Drilling Machine.

For Drilling, We create a program according to our Drilling requirements . The bit of CNC

machine moves in X & Y Direction for Drilling a hole.

STEP-3 ELECTROLESS PROCESS

After Drilling, Now we have to make Drilled hole Conductive so that current from one Side of PCB can flow to another without JUMPER.

We made this possible with the help of Electroless Process. The function of the ELECTROLESS copper operation is to metalize the

entire board with a thin deposit of copper. This Process includes processes like Cleaning, Activator solution Dip, Copper Solution

Dip etc.

ELECTROPLATING

Because we obtain a thin layer of copper at the surface inside the hole of PCB so we

have to make it thicker so that layer got RIGIDNESS. To Achieve this we do Electroplating In which, we deposit Copper from

anode(Copper Bar) to Cathode(PCB). After electroplating now we have 20 microns of copper at the surface

of PCB.

NEGATIVE PRINTING

The photographic image is transferred to copper clad laminate by the screen printing technique.

This technique has been used for a long time for printing cloth, panels and so on, and

reaches its maximum degree of accuracy when applied to PCB manufacture. In the process of negative printing the portion where tracks and pads are situated is

kept open. Rest of the portion of PCB is covered with etch resistive ink. User can use any color of etch resist ink.

ELECTROPLATING AND TINPLATING

Electroplating is done to increase the thickness of Tracks(paths) so that it can withstand with more current and Voltage.

Now tin plating is also done on copper plated PCB tracks to protect them from Ammonia Reaction during Etching.

AMMONIA ETCHING

Alkaline etching with ammonium hydroxide is increasingly used because of its continuous operation, compatibility with most metallic and organic resists, high capacity for dissolved copper, and fast etch rates.

Etching solutions are operated at 120 to 130°F and are well suited to spray etching.

Efficient exhaust systems are required because ammonia fumes are released during operation.

Cu + Cu(NH3)42+ → 2Cu(NH3)4

+

4Cu(NH3)2+ + 8NH3 + O2 + 2H2O → 4Cu(NH4)42+ + 4OH-

 GREEN MASKING

Masking is the process just same as the Screen printing process. In this process the solder masking ink is used to avoid any cause of short circuit. The master artwork for solder resist pattern is prepared and then the solder mask is

applied to PCB by screen printing. The PCBs are dried in air and then thermally cured in the hot air electric oven at 120 C,

for about 60 min.

HAL (HOT AIR LEVELLING)

The bare copper on the printed circuit board generally tends to deteriorate with time resulting in an inferior appearance and making soldering difficult.

So, we coat the remaining copper pads with Solder and tin mixture. These solder coatings have very good shelf life, short solder wetting

time during assembly and very high mechanical stability. Due to the presence of solder on copper, the PCB can withstand

multiple soldering and de-soldering operations during the assembly cycle, with no adverse effect on the solderability of the board.

LEGEND PRINTING

To facilitate assembly and repair jobs, the position and the value of the component is marked on each side of the PCB.

This process is same as masking and printing but white colored ink is used at the place of green and blue.

FINAL SHEARING, ROUTING ETC.

As the last step of PCB Manufacturing ,final Shearing and Routing is done.

Now we cut PCB according to original Required Size Required. Routing is the Process by which any desired shape is given to PCB like

circle, Triangular etc.

BBT Bare board testing generally checks for short-circuits between tracks and

continuity of tracks.

These tests can be performed by fully automatic machines which can test up to

50,000 nodes and networks.

The cuts and shorts in case of single-sided and double-sided PCBs can also be

detected by the age-old method of visual inspection by optical means.

Visual inspection is a very manual approach in that it makes use of people,

good lighting, some type of training defining what is acceptable and what is

not, and good operator judgment.

Usually a comparison to a known good product or the artwork is made.

If the operator has seen the board often, he or she becomes more skilled at

finding faults and looking for faults in likely locations.

As product complexity has increased, we find that many modern products are

not suited to this method.

BBT

CAPITAL REQUIRED TO SETUP PCB INDUSTRY

SINGLE SIDED PCB INDUSTRY COST Starts from Rs. 5,00,000 (without Land

and Building) DOUBLE SIDED PCB INDUSTRY COST Starts from Rs. 25,00,000 (Without Land

and Building) MULTI LAYER PCB INDUSTRY COST

Starts From Rs. 5,00,00,000 (Without land and Building)

THANKS!!...