Arduino ATTiny85 ISP Shield – PCB – Part 1

As promised in Arduino as ISP for ATTiny85 – PCB Revisited, I have transfer printed the design onto a FR4 single sided copper clad board using the modified design.

There were some missing bits in the transfer (as happens from time to time), so I went over the entire trace with a fine Staedtler Lumocolor permanent marker. The Lumocolor is really only ever a backup to toner transfer printing, but I have had some pretty good results using both of them before (Resistance is Not Futile!). You can also see that I’ve filled in the soldering points, that’s so that when I solder, the fillets are stronger (in my humble opinion).The above photo is not too bad, I’ve used a bright white overhead light to illuminate the subject, otherwise it looks like this …

Anyway, enough talk of photography. I didn’t get around to buying any etchant … too poor at the moment, so it’ll have to wait. However, I decided to use some “old” etchant that I haven’t thrown away yet. It should still work, it will probably just take longer and need more agitation than a fresh batch. I guess I’ll find out.

I’ve also printed out the silk layer for applying to the other side. The trick with this is that the copper layer is printed as a normal image, whereas the silk layer is printed as a mirror image. That way, when the two are transferred, they are oriented correctly.

When (if) the etch is finished, I’ll clean the PCB down (acetone and then isopropyl alcohol) and transfer print the silk layer on the top of the PCB and add the pictures of the progress to this article.

Now it’s back to watching telly while I wait for the etch to bite.