Few questions on DIY PCBs.

We are looking to make our own protos to aid in design. We have CNC machine ability so would just write a program for the thru holes before etching.

Questions:
1. How does a DIY proto person create vias in the board?
2. Is the transfer paper something special or is this something over the counter?
3. Where can I find supplies for this like the boards, acid, liquid tin, etc?


I realize this might not be super cost effective but we have a few designs coming down the pipe and it might help us find problems early as well as have the ability in the future for larger board projects.

With the CNC, why not just mill the tracks? There are some programs out here that are set up for this. If you drill the through holes first, how do you stop the etch fluid from going through the holes and removing part of the solder pad around the holes?

Some people use a special very small brass rivet for the vias, some use a piece of a lead from a resistor or cap.

A lot of information on this is available in the online group of HomebrewPCB.

Yeah, I guess we could just machine the thing complete but I figured the thin copper plate would peel up and be problematic. Is there not a plating procedure or standard method to add vias?

thanks for the website referral. I will certainly go hang around there for a bit and see what I can learn.

fastline said:

We are looking to make our own protos to aid in design. We have CNC machine ability so would just write a program for the thru holes before etching.

Questions:
1. How does a DIY proto person create vias in the board?
There are a few methods. The simplest one Ive seen for creating true vias calls for drilling and electroplating before etching, to create the vias. You can also buy little plugs to stick in the holes. The method I prefer is to simply drill 0.021" holes for vias, and stick an 1/8w resistor leg in and solder the top and bottom.
2. Is the transfer paper something special or is this something over the counter?
You should be able to get it from any Staples/Office Depot/etc. Again, personally I print with a laser printer, and photocopy the design onto an overhead transparency, so I can expose the board with UV
3. Where can I find supplies for this like the boards, acid, liquid tin, etc?
You havent filled in your location so Im not sure where youre from, but I can buy it from a number of stores in the city, so check around. Otherwise, if youre in the states, digikey and mouser will ship those chemicals to you


I realize this might not be super cost effective but we have a few designs coming down the pipe and it might help us find problems early as well as have the ability in the future for larger board projects.

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Replied in-text.

fastline said:

Yeah, I guess we could just machine the thing complete but I figured the thin copper plate would peel up and be problematic. Is there not a plating procedure or standard method to add vias?

thanks for the website referral. I will certainly go hang around there for a bit and see what I can learn.

Click to expand...

The via plating is a expensive process that not too many hobby/prototype level people use.

As far as the milling, they use a pointed single flute engraving cutter to do it and it works real nice.

A paper I haven't tried is called Disolvo paper for the transfer. Remember that generally a modified laminator is required as well.

When I had access to a photolithograhy lab, I printed on polyester paper and coated the boards using a spin coater and baked per the instructions. A technique that I like to use for adhering the exposure mask to the PC board is a little water. The surface tension of the water holds the mask. This is instead of a plate of glass.

A tougher problem is aligning of the mask. I did create two holes just for alignment which would pass a thumbtack. I did the hole prior to coating and it creates minor uniformity issues with the spin coating so the holes need to be near the edge.

I have used the sun for exposure many years ago.