Olson, Jack C wrote:-
>I was under the impression that black oxide provided more "tooth" for
>bonding copper to the substrate material.  Recently I was told is was just
>to protect the surface during handling. Since I can't find it in Coombs
>Handbook, can anyone briefly explain?
Hi Jack
You are right, the reason for oxide treat of copper foil is to improve
the bond strength. It makes handling more difficult as it is easily
marked. Early oxides were cuprous and readily attacked by acids. They
could also be quite thick and hence led to pink ring phenomenon around
holes. Nowadays the norm is to reduce the oxide coating to cupric by
post treatment. This is impervious to acid attack and is also much
thinner which prevents pink ring formation.
There are alternative finishes but, as far as I know, none of them give
higher bond strengths than reduced oxide.
Paul Gould
[log in to unmask]
Teknacron Circuits Ltd
Fax: 1983 865141
Tel: 1983 866531

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