How to Etch your own circuit board?

[lgehrig4]

Hi,

I purchased an etching kit from RadioShack for a small amp project. I cleaned the copper on both sides and followed the directions to a "T", but it did not work. The directions say to leave it in the solution for about 20min. In 20min almost no copper left the board. I left it in over an hour and still not all the copper dissolved, however some of the areas that were not supposed to dissolve did.

Does anyone have any advice, tricks or knowledge that they can pass on to me? The directions are lame and I'm sure there is more to it than they explain.

Thanks
Jeff

[jackinnj]

it helps if the etchant is warm -- but don't warm it on a gas stove since the reaction releases hydrogen.

i now prefer to use hydrogen peroxide and muriatic acid. the hydrogn peroxide can be bought at the drugstore for under a buck for a quart, the muriatic acid is at the hardware store -- used to clean stone, it's pretty nasty stuff (Dilute hydrochloric acid). The HCl acts to accelerate the oxidizing effect of the H2O2 -- it takes less time than ferric chloride.

[richie00boy]

If you had to expose the board to UV light to create the mask then I'd say that you either didn't expose it for long enough or didn't clean all the residue off after developing.

[RetroAudio]

jackinnj - how many parts acid to peroxide do you use?

[nick_g_evans]

I have just started to do this myself also. My first couple tries were hideous, but my third was a clean success!

As you have probably heard, there are several ways to mask the copper. The some ways I know of are permenent marker, laser print transfers, and the Radio Shack stickers.

I had no success getting those Radio Shack stickers to stay on, and I don't recommend them.

The only way I've tryed to etch with is using a permenent marker. It may sound like it wouldn't give good results, but with good planning, patients, and a steady hand, a nice turn-out can be had.

To ensure good results with this method be sure to clean the board before hand and after etching. In both cases I used fine-grit sandpaper, soap and water, and alcohol.

I used a Sharpie to mask. When I drew the traces, I copied and pcb layout I had found online and used the IC I needed to make sure it would line up correctly. When applying the marker, make sure that there is a thick layer of ink covering the traces, or the solution will eat right through the copper underneath.

There are a couple tricks I have heard and learned with this method. One I learned is to pull the board out mid-etch, wipe the board, and go back over the traces with the marker. This will leave thicker copper tracks and more unwanted copper disolved.

Another trick is to completely mask a whole row of a DIN IC and separate the pads with a knife after etching. This will allow for wider pads for the IC and better alignment.

Follow these steps and you should quickly learn how to cheaply and easily etch with just a marker and some solution.

I plan to try the laser printer iron-on masking next. I read a review somewhere that the best paper for this is Staples photo paper. We'll see how that turns out.

Oh yeah, by the way, make sure you don't get any solution on your hands. If you do, don't eat any crackers or anything. I did, and get not get to sleep that night because I could not get the taste and smell out of my mouth.

I hope all this helped.

[ingrast]

You may want to check Think & Tinker for a dry resist process I use and recommend.

Select only the chapters relevant for you, there are procedures and products for through hole, multilayer and solder mask processes also.

You may substitute an ironing appliance for laminator - be ready to spoil some trials - but cut no other corners. I can routinely make .01" tracks this way after tunning carefuly the process.

Rodolfo

[markp]

I use dry transfers, toner iron-ons, and sharpies to get the patterns I want. Make sure the board is very clean and oil free(no fingerprints) and the dry transfers stick fine and work well. The best method is to get some laser printer transpearancy sheets and print your pattern on them and iron the pattern onto the board, it takes practice to get the right tempuratures on the iron but its worth it! You can go over the iron-on with a sharpie if you wish. If you have very wide traces you can go over them with nail polish. When done acetone takes the polish and toner transfer off the traces.

[kmj]

here's one:
Devil H@ck's page

[TwoSpoons]

Pulsar for the toner transfer method. Read through and you'll see that toner alone is porous, leading to pinholing. Toner reactive film is supposed to fix this. They also have a sponging technique for etching, that I've not tried.

I've had good results using toner transfer, and ammonium persulfate etchant.

Keeping your etch bath at 50C is essential, also constant agitation for even etching.

[jacco vermeulen]

With luck you can find a HP flatbed plotter in a dumpster.
The pens should be filled with etch resistant ink.

a PCB board can be positioned on the plotter bed, the circuit is directly written on the board by the pens.