First go at etching a pcb – plastic tray was a problem.

[prof328]

Absolutely new to electronics, and my first post.

I bought a pcb starter kit from Maplins, decided to try the hydrochloric acid and peroxide etchant, bought the components and mixed a small batch.

However when I came to etch the solution did not work as I imagined, after three unsuccessful attempts I concluded the plastic/polythene tray was causing the problem.

The acid seemed to be attacking the plastic tray and forming a slimy film that interfered with the etch process.

To verify this I bought a ceramic dish, mixed a new batch of etchant and tried again, the experience was in complete contrast worked as expected with no slime generation.

Nowhere, had I read that the etchant used may be a problem with plastic trays.

Just thought I would post this in case it may save someone else the same problem.

Incidentally, I have yet to produce a workable pcb my new problem is the fine traces between pins, they fail to etch properly leaving tiny connections between the pads and the traces, but I will persevere, I can’t make the pads any smaller so I will thin the trace at that point in the hope to get better clearance.

 

[jpanhalt]

Hydrochloric acid + hydrogen peroxide is a powerful oxidizer. A cheap polystyrene tray might be affected. I suspect a polypropylene or high-density polyethylene tray would be stable. Ferric chloride is less reactive toward plastics.

John