I forget the details as this was going back to about 1970 but, in a
former life, we did just this kind of thing to reduce barrel cracking.
However, if I remember rightly, the electrolytic flash coating was only
about 5 µm. I forget which order they came in but the flash coating and
the 20 µm main plating were done in different baths, one being sulphate
and the other pyrophosphate. The theory behind it is that the main
plating had a better throwing power, while the flash coating had a
better adhesion to the electroless copper, because of epitaxial growth.
Again, if my memory serves me correctly, we used this technology for
only a short while, perhaps 12 months, after which it was replaced by a
single bath which had sufficient quality in both aspects to no longer
justify the extra step. Remember that this was in the relatively early
days of through hole plating, and finding the right solution (no pun
intended) was quite an adventure.
I see no justification for doing this today – copper plating has come a
long way in 40 years!
Brian
On 02/11/2010 06:16, Uppina Nagaraj wrote:
> Hi All,
>
> We have a low build electroless Copper plating for Through Hole
> metalization, which's giving around 0.5 to 0.6microns of Copper.
>
> The subsequent processes are pattern image printing followed by
> pattern plating (electrolytic copper plating).
>
> One of our customer has a requirement to do flash Copper plating
> (electro plating) of around 8 to 10 microns, immediately after
> electroless Copper plating, prior to pattern image printing.
>
> I want some inputs on the above.....
>
> Is there a distinct advantage on PTH reliability by having
> 8-10microns of electroplated copper immediately after
> electroless Copper plating.
>
> Will having additional flash plating have better Thermal
> stress& Thermal Shock performance.
>
> Thanks!
> U.Nagaraj
>
>
>
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