Rod:
You might try this, it requires a little more work and an AA, but it will
tell you if the chromate is completely removed from your work. Providing
that the conversion coating is chromate based. Check with your supplier.
Take a 2x2,3x3, whatever, copper laminate coupon sample. One uncleaned
sample laminate and one cleaned laminate, two 30 to 50 percent nitric
solution in beakers that the coupons will fit into. Immerse each coupon into
a beaker for about a minute. Take the nitric solution and analyze for
chrome.
Good Luck,
Michael Newman
Process Engineer
"X" Circuits, Inc.
>From: Rudy Sedlak <[log in to unmask]>
>Reply-To: "TechNet E-Mail Forum." <[log in to unmask]>, [log in to unmask]
>To: [log in to unmask]
>Subject: [TN] No Chromate Test, but an alternate
>Date: Wed, 22 Sep 1999 10:36:12 EDT
>
>Yet another test for cleanliness:
>
>Put a drop of the 0.1N Silver Nitrate solution often used for titrating in
>labs on to the Copper.
>
>If the surface is dirty, the Copper turns black slowly, unevenly, and the
>black will rub off.
>
>If the surface is clean the Copper turns black INSTANTLY, evenly, and will
>not rub off (except with a pencil eraser).
>
>It is a judgement call, (no numbers, drives ISO people bonkers!) but a real
>good test.
>
>Rudy Sedlak
>RD Chemical Company
>
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