the process
How are PCB’s (Printed Circuit Boards) made?
The process involves 18 complex steps.
The design
The PCB designer routes the traces and places components based on a schematic diagram.
Printing the design
The design of the PCB is printed onto a film that shows the details and layers of the board.
Creating the substrate
Copper is bonded to both sides of the substrate (epoxy resin and glass fiber) using a large oven.
Printing the inner layers
The design is printed to a laminate using blue photo-sensitive film (photoresist) that covers the structure.
Ultraviolet light
The photoresist and laminate go under ultraviolet lights that harden the photoresist, revealing circuitry.
Remove unwanted copper
A chemical solution eats away at the unwanted copper. The hardened photoresist remains intact.
Inspection
After the photoresist is removed, an X-ray machine is used to inspect the board for any defects.
Pressing the layers
Prepreg (epoxy resin) and copper layers are aligned with metal pins, pressed together, and clamped.
Laminating the layers
The PCB goes through a laminating press, which melts the prepreg epoxy and fuses the layers together.
Drilling
Holes are drilled into the layers by a computer-guided drill to expose the substrate and inner panels.
Plating
The PCB is bathed in chemicals which coat the panel with a thin copper layer and also plates the holes.
Outer layer imaging
Another layer of photoresist is applied to the outside layers and UV light hardens the photoresist.
Plating
The panel is plated with copper a second time. A thin layer of tin guard is then plated to the board.
Etching
Acid removes any unwanted copper. The tin guard layer protects the copper intended to remain.
Solder mask application
The solder mask epoxy is applied and baked onto the board, which gives the board its unique green color.
Silkscreening
Component labels and outlines are silkscreened onto the board using white ink. Then it is coated and cured.
Surface finish
The PCB is plated with a tin finish which will increase the quality and bond of the solder.
Testing
Finally, a technician will perform an electrical test on the board using an ultra fast “flying probe” testing machine.
This video was created by Strange Parts to show the
entire manufacturing process from start to finish.
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