Homemade Printed Circuit Boards Electronics & Audio
The ability to make your own printed circuit boards is a real boon to the electronics hobbyist, in so many ways: No more waiting for boards to arrive. It’s economical with no minimum order or shipping charges, and the quality is excellent and fully under your control. Board revisions for revised (or corrected) layout are fast.
I started making my own circuit boards a few years ago and I’ve refined my technique continuously since. I’m at the point where it’s much less trouble for me to make a circuit board to test a design, rather than breadboarding (I really don’t like breadboarding though). I use the toner transfer method, which seems to be the most economical for one-off or small numbers of boards.
First, credit where due – I learned much of what I know from Tom Gootee’s site. I use his method with just a couple of changes and get excellent results.
Most of my boards are double sided. Usually, I use the top as the ‘silkscreen’ but do this in copper – etched from the top layer.
I start by printing the top and bottom layer onto the transfer media, in this case it’s HP glossy presentation paper. I do the printing on my HP laser printer.
To align the layers, I index the edges of the print, by using a ruler (strip of wood in picture below) to space the cut line away by a fixed distance:
I then use a razor knife to make the cut. I do this on two edges, to get a corner that is used to align the prints.
The arrows point to the corners that line up to orient the prints correctly. I use staples to hold the sheets together, leaving the opposite sides open to slip the boards in:
I cut the boards to size and clean them up with 220 grit sandpaper. I then wipe them clean with lacquer thinner (acetone works too) to remove any residue that will stop the toner from sticking:
A clothes iron on max settings (no steam) and lots of pressure and rubbing transfer the toner to the board:
A quick soak in warm water and I can peel the paper off(above, right). A plastic scrubbing pad and warm water are used to remove the rest of the paper from the board.:
Sometimes, there are repairs to do. I used a fine point Sharpie (only this brand works – I’ve tried others) for small areas and a paint marker for larger ones:
Next, it’s time to etch.
The etchant is 1 part muriatic acid to 2-3 parts hydrogen peroxide. Both of these are readily available – the acid is used to clean concrete and brick and can be bought at a home supply or hardware store. The peroxide is sold at the drugstore:
After the etch is done, I rinse thoroughly with water and clean with fine steel wool:
The boards are now ready for tinning and drilling.
After cleaning, if I don’t have any traces to solder on the top layer, I use lacquer to clear coat. I only do this on the top, silkscreen layer. This stops the copper from tarnishing:
To prep for tinning, I give the solder side a very thin coat of plumbing flux. I use this because it makes the solder flow really well, without leaving the hard buildup that rosin flux does.:
I used flux core solder and a cheap soldering iron to do the work::
Melting the solder on the tip and spreading it on the traces. The plumbing flux can eat tips pretty rapidly, therefore it’s best not to use a quality iron for the tinning.
After the boards are tinned, the flux is washed off with warm water and soap.
It’s worth mentioning that tinning before drilling is the correct sequence. If the holes are drilled first, they will fill with solder and you’ll need to drill them out again.
Next, the holes are drilled. I drill the holes free hand, with a Dremel equipped with a chuck. I use HSS bits and just sharpen them occasionally until they wear out or break (almost never). I typically get thousands of holes from a single bit. Others use carbide bits and drill presses but I believe my way is the fastest and cheapest. The boards I’m working on here have one hole size and took less than a minute to drill:
On this particular board, I’m experimenting – surface mounting a through hole DIP IC. Seems to work well:
The board also has a SMD IC, a digital potentiometer:
That was a little trickier to solder with an iron. It’s a pretty good demonstration of the resolution capability of the print and etch.
Another example of a homemade board, this one is a single sided board but is still double side printed – the toner is left on the top layer as the silkscreen. For this one, I protected the silkscreen with a transparent green paint rather than clear lacquer:
A pair of larger ones, these are roughly 4″ x 5″, and have a copper silkscreen:
As shown, there’s really no compromise with quality in these homemade boards. Mastering the process is well worth the effort, if you do any great amount of hobby electronics.