have you tried with sulphuric acid and H2O2 added to it?
this should not eat up your plating.
it blackens it but shouldn't eat it up.
regards
st
26.04.2003 19:46:40, "Max Davies" <
max.davies@...> wrote:
>Hi everyone.
>
>A newbie to this group, I am (perhaps over-ambitiously) attempting
>to set up a micro through-hole plating line at home. It's a lot
>more involved than I ever thought it would be, but I now have most
>of it working fine. ...Except what should be the easy bit - the
>final stage - the etching!
>
>
>To give a brief description of what I do...
>
>STAGE 1: Starting with plain, copper-clad board, I do the drilling.
>STAGE 2: Apply photopolymer laminate, then expose & develop. (This
>is positive photopolymer, so the copper which will ultimately become
>tracks is exposed to the air on developing the pattern)
>STAGE 3: Go through a 6-stage process to electroless-plate the
>entire thing (including the holes & edges). The copper cover it puts
>on is pretty thin, but uniform at 1-2 microns.
>STAGE 4: Electroplate the copper - this gives reasonable thickness
>to the copper applied in stage 3 - I aim for 25 microns.
>STAGE 5: Electroplate with tin to 10 microns. This
>(theoretically!) protects the copper from etchant.
>STAGE 6: Remove remaining resist. Then etch. This should leave
>the tin-plated areas untouched, everything else should be zapped.
>
>
>But alas no! Stage 6 fails, because both tin ∗and∗ copper are
>etched, leaving me with a fine, blank piece of fibreglass! It
>matters not whether I use Ferric Chloride or Sulphuric/Peroxide
>etchant - they both destroy what has been so lovingly created!! So
>I reckon there must be something awry with my tin plating.
>
>It's a total impasse, and nothing I do, from increasing/decreasing
>current to re-formulating the tin plating bath according to
>manufacturer's instructions seems to change things.
>
>Does anyone else use a similar process, or have any clue about what
>might be the problem here?
>
>Max.
>
>
>
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