Hi Tgyee,

We have encountered similar solutions to the pink ring problem, and in
response to my previous em and Technetters' responses, the problem is not
as frequently  related to drilling, as Richard F., of Atototech Canada
alludes.

Best Regards,
Lenny Kurup
 

On Mon, 21 Jul 1997, tgyee wrote:

>      How come chemical vendors almost always emphasize that their oxides 
>      are converted/reduced? Is the reduction process a relatively new 
>      technology?
>      
>      If so, before the reduction process is available, how did PCB shops 
>      prevent pink ring formation?
>      
>      The reason I ask is that, since there is a "pink ring" solution - 
>      reduction of oxide, whenever there is pink ring occurence, one would 
>      point at the reduction process by first instinct, forgiving other 
>      possible pink ring causes. We once faced an extremely painful pink 
>      ring crisis, and were able to end it by improving the oxide reduction 
>      process. However, during the crisis, I found out that I can separate 
>      the oxide-coated copper from the prepreg by using a knife. It was that 
>      easy even without thermal-shocking the board. And after the separation 
>      there was not even a bit of oxide seen on the prepreg side. I 
>      considered this as an evidence of poor lamination.
>         Although we solve the pink ring by oxide reduction, I think may be 
>      we might not have the problem in the first place if the lamination is 
>      in perfect contition.
> 
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