PCB etch question

[tom42107]

I etched my first board and have a question. I'm not sure what the discoloration is. I guess it's toner. I've scrubbed the heck out of it, (carefully), and can't seem to get rid of it. Do you think it's toner or something else? Thanks.

 

[tomchr]

Looks like you used a toner transfer process. The discoloration is caused by the etchant seeping through the toner. It's eaten a bit of the copper. That's pretty common with toner transfer, actually.

What you can do is to coat the board with tin. MG Chemicals' Liquid Tin is what I use. It doesn't give you the copper back, but at least it prevents the copper from oxidizing further. It also gives you a surface that's easy to solder to.

Give the board a good scrub with a ScotchBrite (or equivalent) pad before tinning it.

~Tom

 

[tom42107]

Thanks tomchr, it is toner transfer. I'll try the liquid tin.

 

[csom]

This is one of the best video tutorials on Home made PCB. Though it is not in English, it's very detailed and covers every step.
Just wanted to share .
Fabricación de circuitos impresos con el método de planchado - YouTube

 

[dangus]

Fine sandpaper or a scrubbing pad might clean that up if it hasn't etched too deep.

In my experience, the liquid tin was expensive, and not much easier to solder than corroded copper. Better to spray the board with a conformal coating or varnish.

 

[googlyone]

When you make PCB's at home using PCB transfer, you will find that at times it does not work perfectly well. My experience is that the major factors that drive this variation are:
- Cleaning of the PCB prior to ironing
- How well it is scrubbed prior to ironing, I have noticed a correlation between how carefully I prep the pcb surface and how well the transfer works
- Iron temperature and time - you will need to experiment here
- How carefully I "work" the transfer once ironed on

That said, looking at your photo, you have acres of copper in there... if you scrub the PCB with a scourer and solder the bits on it will work just fine.

If on the other hand you are concerned with the aesthetics of the solder side of the PCB, then you might be best off making another board.

 

[tom42107]

Thanks for the tips everyone. I'm not super concerned with the look of the copper but I might try to etch it again. Dangus, is it harder to solder through the varnish? Thanks.