Details on parameters

A project log for PCB exposure unit

An exposure box for PCBs made of UV LEDs

JohannesJohannes 09/06/2018 at 19:200 Comments

I promised to share some details about timing and chemicals.

So far I used the exposure unit three times. At first with mixed results and the third time with quiet good results. Three is not an adequate sample so future results may vary.

Safety first

Whenever you use chemicals be aware of the potential dangers.

I will not go into detail about all dangers encounters while etching PCBs, but you are generally good to wear personal protection equipment, i.e. safety glasses, gloves and tight clothing.

If in doubt, ask someone who may have some experience in the field or don't do it.

Also: Do not store chemicals in bottles used for food or drinks! Pharmacies sell glass bottles for some bucks. Use them!

Also label every bottle.
Even if there is only one or two.
Even if you are the only one using them.
You know the difference, someone else may not.
And 'someone else' may be the ambulance who try to rescue you after something (else) has gone wrong.
(Thankfully I do not speak from experience)

My current setup for PCB etching is:




While working on the board, I had no time to take photos. So this is the hot bath without etchant.

After treatment

When you finished the last step above, the board is (theoretically) ready for soldering.

Anyway it is easier, if you remove all photoresist and replace it with solder-varnish.

It is way easier to solder to that, even if it says that the photoresist should be easy to solder - it is not.

Photoresist is (partially on the right) removed with alcohol or acetone.

And this is the board with solder-varnish.