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I make home-made cheap PCBs (I use toner transfer, then acid etching method now, but I might use UV etching someday). I wonder what is the best (and cheap) way to control if there is no problem on connectivity of the traces?

I control the connections by a multimeter, but it takes too much time to check all the connections with it especially if I make 10 or more PCB at a time. Sometimes I see that there are very tiny gaps that disconnects the paths and too hard to see them by bare eye. Is there any spray or can I use camera (webcam) to detect the broken paths, or any smart method?

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    \$\begingroup\$ Use a better process! I don't have any problems with UV and photo-resist boards. \$\endgroup\$ – Leon Heller Jun 23 '13 at 8:58
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The problem of broken (or shorted) traces exists in any (especially DIY) PCB fabrication technology, whether toner transfer or high end photolithographic film process - The difference being the trace widths affected, of course.

Validating trace integrity of multiple boards can be done in a DIY environment by using a home-grown bed-of-nails testing rig, consisting of a bunch of pogo pins on a rigid base, and perhaps a row of LEDs to indicate respective trace continuity.

Pogo Pins (source)

Adafruit has a tutorial on how to set this up.

If it is for a small run with through-hole part spacing and 0.1" trace distances, and the rig is unlikely to be needed again, a functional bed of nails can be set up using a breadboard and some effort.


Even the most expensive fabrication facilities have at least random sampled board integrity testing as an offered service. If anyone tells you a technology change will guarantee no more broken traces, they are merely advocating their preferred approach, without basis in fact.

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  • \$\begingroup\$ I've never had any broken tracks with my home-made boards. \$\endgroup\$ – Leon Heller Jun 23 '13 at 11:11
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    \$\begingroup\$ If its a 'one-off' or just a few boards I find a good light and a strong magnifying glass a great aid. It also helps to use toner transfer paper (dextrin coated) and toner foils to seal the track before etching. I also pre-heat the board (cover with blank sheet first then iron) before I place the transfer paper. \$\endgroup\$ – JIm Dearden Jun 23 '13 at 12:57
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    \$\begingroup\$ Magnifying glass, or a cheap USB microscope works as well. \$\endgroup\$ – Anindo Ghosh Jun 23 '13 at 13:13
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If you are getting disconnected traces, it means your traces are thinner than your process supports.

However, before you change to the UV method, there might be room for improvement in your current process. If you decide to stick with the toner transfer method, and not change anything else in your process, you can increase trace width, for example. You should be able to tell, by trial and error, what's the minimum trace width you can achieve.

Another bit that influences the quality of the toner transfer method is the transfer paper used. I didn't use to get any disconnected traces anyway, but I recently changed the transfer paper because the previous brand was hard to remove from the board. The results were remarkable. I can now make much thinner traces without even having to use a sharpie to fix them or to fix problems near the borders.

For those living in Brazil, it may be useful to know the paper brands. Before I used glossy ink jet paper from a company called Sistem (with I, not Y as in System) and now I use glossy ink jet printer paper from Pimaco/Bic. The latter is MUCH better for tonner transfer.

Also, a new toner helps a lot.

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