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Problems making PCBs

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Well I've made several attempts now at making a PCB and all have ended in failure, although my last attempt was a lot better than the first.
The problem I'm having is that my developer (NaOH) removes or damages isolated traces and takes quite a bit longer with more tightly packed traces / pads resulting in even worse damage.
I've tried various exposure times from 1 to 7 minutes using a UV LED array, 1 minute 30 seconds seems to give the best results so far, as for media I'm using a 90gsm tracing paper doubled up which was recommended in a tutorial I found.
As for the developer I've tried various concentrations from super strong to very weak, aside from the greater control with a weaker solution this has not helped.
Apparently adding sodium metasilicate to NaOH can prevent over etching but I'm unsure of the correct concentration.

Any advice would be greatly appreciated.  ;)

Oh and the trace size I'm using is 13mil

The only etchants I've had any success with are ferric chloride and amonium persulphate.

I think the problem with the acid/base etchants is that they produce H2 as part of the chemical process and the bubbles of H2 cause the resist to lift along the exposed edges --with resultant undercutting and damage.

From memory, the good etchants perform an exchange of ions that produce no gassing.

You're confusing developer with etchant.
I'm using a photoresist so you have to develop it with NaOH or similar developer before etching with ferric chloride.

Etching is not my issue, developing is.

i've never heard of tracing paper for exposing circuit boards....

lots of info available on the toner transfer method.

For photoresist developer, NaOH is very tricky to use because results very much depends of concentration and temperature. Few more seconds or few degrees higher temperature and all your effort is gone...

I strongly suggest DP-50 developer, it is practically foolproof and work extremely well. You can get it of ebay, or google for supplier.


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