A Brief Overview On PCB Fabrication Process
The backbone for any electronic device is its
printed circuit board to PCB. PCBs act by routing the electrical signal to the
electronics of the device to meet their electrical and mechanical circuit
requirements. This routing of electrical impulse is done by network of copper
pathways which determines the unique role of each part printed on the circuit
board.
Types and
variation
PBCs although in general serves
similar purposes, however the PCB fabrication process slightly varies according
to the type of circuit board that is to be manufactured. Generally there are
three main types:
- Single Sided Circuit Boards
- Double Sided Circuit Boards
- Multi Layered Circuit Board
A brief
manufacturing process
The PCB
fabrication process introduced by leading manufacturers
is elaborate and intensive. A concise account is given below
Design: Any manufacturing process
begins with a design. The most commonly used software for PCB designs are
Altium Designer, OrCAD, Pads, KiCad, Eagle etc.
Printing: After the design has been
finalized the design is printed on a special plotter printer. This is essentially
a photo negative version of the real PCB.
Printing of
copper layers: the basic PCB comprises of a laminate board. This laminate board serves
as the body for receiving the copper. This process whittling away of copper for
the film design
Removing of
extra copper: An alkaline solution is used to eat away the extra copper that is not
covered by photo resist.
Inspection
and alignment: After cleaning, the holes from the earlier are used to align the inner
and outer layers. For alignment the layers are place on optical punch where the
punch drives pin down through the holes to layer up PCB. Another optical punch
is performs the optical inspection.
Laminating: Once the layers are
detected defect free they are laminated and sandwiched which is done by metal
clamps.
Drilling: A computer guided drill is
utilized for making the holes
PCB plating: After the drilling a chemical
solution is used to fuse different layers of PCB together.
Imaging the
outer layers: A photo resist is applied on the outer layer to make it more resistant.
Etching: Any unwanted copper is
removed by etching, tin guard is sued to protect the copper layer during
etching.
Solder Mask: After etching and
cleaning soldering ink along with solder mask is applied. and the boards are
blasted under UV rays. Then baked for the mask to be cured.
Finishing: For silkscreening or
finishing PCBs are plated with gold silver or HASL so that components are able
to solder to pads and protect the copper.
Testing: After finishing touch a
battery of electrical test is run for testing different areas of the circuit.
Cutting and
profiling:
After the piece tests defect free they are cut into different pieces as per
profiling and purposes.
End note
The entire process of PCB manufacture
is elaborate and highly complex requiring a mixture of lot of chemical and high
end precision techniques. Industry experts in PCB fabrication can provide
different high end PCB circuits as per the specifications of your device needs.
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