Rich,

The black oxide is not used to prevent pink ring. It is used to improve the
bond between prepreg and copper laminate during lamination of innerlayers.

In the oxide process itself the subsequent post dip does, in a sense, change
(reduce) the copper dendrite structure thus making it more resistant to pink
ring (acid attack on black oxide).

Alternative materials to replace black oxide include reverse and double
treated foils. A new accepted wet process introduced to the industry is a
peroxide/chlorite-based process that, what I believe, changes the copper
surface topography (increased roughened surface) to mimic a reduced oxide.

Black oxide is considered a standard in our industry however, because it can
only be used in an immersion process and requires good pre-cleaning it
becomes a bottleneck in production. The alternative methods are for the
purpose of relieving that bottleneck.

Hope that helps.
Michael Newman




>From: [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] Black oxide process
>Date: Thu, 6 May 1999 10:32:23 -0500
>
>In producing multilayer PCB's, there is an oxide process used to prevent
>pink
>ring.  Usually this process is called the "black oxide process" and
>requires use
>of a reducer solution containing an amine borane.
>
>Is this process considered a standard in the PCB industry and is it's use
>increasing?
>
>Are there alternative processes which accomplish the same objective?
>
>What is the future trend to eliminate pink ring?
>
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