“PCB”-AMIT NIKAM

-ASHI NAGARIYA

CONTENTS What is a PCB? Materials of a PCB Parts of a PCB 1.Components 2. Pads 3. Traces 4. Layers 5. Jumper 6. Solder Mask 7. Silk screen Multilayer PCB Advantages Disadvantages Uses References

What is a PCB?

• Printed Circuit Board• Electronic Board that connects circuit

components• PCB is populated with electronic

components • PCBs are rugged, inexpensive, and can be

highly reliable• Mass manufacturing

MATERIALS OF PCB• Conducting layers are typically made of thin

copper foil.• The board is typically coated with a solder

mask that is green in color. Other colors that are normally available are blue and red.

• Unwanted copper is removed from the substrate after etching leaving only the desired copper traces or pathways

PARTS OF A PCB• Components• Pads• Traces• Layers• Jumper• Solder Mask• Silk screen

COMPONENTS• Components are the actual devices used

in the circuit.• This includes input/output connections.• I/O ports, including power supply

connections, are also important in the PCB design.

PADS• Location that components connect to.• You will solder components to the pads

on the PCB.• Pads will connect to traces.• Pads have an inner diameter and outer

diameter.

TRACES• Traces connect pads together.• Traces are essentially the wiring of the

PCB.• Equivalent to wire for conducting signals• High current traces should be wide• Signal traces usually narrower than

power or ground traces.

LAYERS

• Two layers- TOP and BOTTOM• Most of the components reside on the

top layer• Fewer traces on the top layer• Components are soldered to the pads

on the top layer of PCB • Higher circuit densities• Most soldering done on bottom layer

JUMPERS• Often, many signal wires need to exist in

too small of a space and must overlap.• Running traces on different PCB layers

is an option.• Multilayer PCBs are often expensive.• Solution: use jumpers

SOLDER MASK• Protect copper traces on outer layers from

corrosion• Areas that shouldn't be soldered may be

covered with polymer resist solder mask coating

• Designed to keep solder only in certain areas• Prevents solder form binding between

conductors and thereby creating short circuits

SILK SCREEN• Printing on the solder mask to designate

component locations• Readable information about component

part numbers and placement.• Helpful in assembling, testing and

servicing the circuit board

MULTILAYER PCBS• More then a top and bottom layer.• Typically there will be a power plane,

ground plane, top layer, and bottom layer.

• Sometimes signal layers are added as needed.

ADVANTAGES• Small• Compact• Contained in a convenient, rugged board• The circuit board fabrication cost (pcb cost) is lower with mass

quantity production.• Electronic circuit characteristics are maintained with a proper circuit

board design. • Component wiring and assembly can be mechanized in a circuit

board manufacturing facility. • PCB’s offer uniformity of electrical characteristics from assembly to

assembly. • The location of electronic parts is fixed and so it simplifies

components identification and maintenance of equipment. • Inspection time is reduced because printed circuitry eliminates the

probability of error. • Chances of wrongly wiring or short-circuited wiring are minimized.

DISADVANTAGES• Re designing is required for the new type of

circuit operation. • Very hard to get repaired if it gets damaged.• We can not update it , once printed. • Etching of this PCB generates chemicals

which are the harmful for the environment.....

USESIndustrial PCB Manufacturing• Some examples of PCBs that Tabtronics

has manufactured for industrial use include:

• Controls for ultrasonic technologies• Flex circuits with piezoelectric transducers• Field controls for water treatment systems• Process thickness measurement control

Medical PCB Manufacturing• Some examples of PCBs that Tabtronics has

manufactured for medical use include:• Dosimeter product assembly• 2-axis body movement tracking device used by

doctors and researchers• Eye measurement product with

remote transmitter and receiver• Hospital inventory control devices

REFERENCES

• www.pcbexpress.com• A Practical Guide to high-speed printed

circuit board layout