Visit to a PCB fabricator
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    I designed a PCB for a robotics workshop held in our college recently. We needed 20 PCBs in all, so we decided to get them fabricated at a local pcb fabricator in the suburbs. I jumped on the opportunity to capture the whole pcb fabrication process on camera.

The fabricator's setup was typical by Indian standards. It looked chaotic at first sight, but as usual, there was order in disorder. Although it wouldn’t be right for me to comment on the working conditions, I can sum it up in one word - "pathetic". The owner was friendly and gave us a small walk-through of the entire process. The shop was primarily divided into two sections, one was the mechanical, where cutting, drilling and polishing took place while in the other half, printing, etching and tinning was done.

The whole process starts with cutting of copper clad boards into appropriate sizes. Parallely, a screen is prepared for 'printing' the pcb pattern on the boards. It’s an usual screen printing process.

1. A negative is developed from the pcb layout
2. A positive layout is then developed on a printing screen, which consists of a finely woven fabric.
3. The pattern is then printed on the pcb by placing it under the screen and applying the colour over it.
4. The printed board is then dried in an oven.
5. Now the board is etched using ferric chloride solution in an etching tank.
6. After etching the board is washed
7. Holes are then drilled (one at a time - the most time consuming process of all )
8. The PCBs are polished using a steel wool
9. If necessary, solder mask is applied using the same screen printing technique
10. The board is tinned
The PCB is now complete and ready to ship!

click to enlarge:-

PCBs being cut into required sizes	Stack of pre cut PCBs	The developed screen
Application of colour on the screen, (screen printing)	The printed pcbs are left to dry on a nail stand	The oven
You can see the pcbs with and without solder mask	Etching tank, most hazardous place of all !	Drilling
There were in all four small drill press in this shop	The PCBs are polished before tinning.	Application of the solder mask
The tinning machine consists of a rotating roller dipped in molten solder	A close up	The finished PCBs being cleaned
	Our PCB !

28 march 2006