Re. Bubbles  on the vias.

Francis is quite on the dot. More so the Electrolytic copper continues to
accumulate organic contamination. This is easily checked by Potassium
Permanganate treatment -
The organic embedded in the plated copper matrix will vaporise during solder
and outgas.
am keen to be corrected.
Anil.
-----Original Message-----
From: Francis Lai <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Friday, July 16, 1999 8:45 PM
Subject: Re: [TN] Sloder bubbles on the VIAs


>"Tempea, Ioan" wrote:
>
>> Hi,
>>
>> now that the problem with the blistering solder mask is fixed ( we sent
the
>> boards back since backing them was of no use), I have another one.
>>
>> Some of our assemblies have a high density of VIAs. On these products,
>> pretty often we get after wave some solder bubbles over the VIAs, some of
>> them exploded, like degassing. Since on some we see the same bubbling
even
>> on the fiducials, I wonder if the humidity is the only one to blame, I
even
>> wonder if there's any issue related to humidity at all.
>>
>> So, what could it be? Incompatibility between flux and solder sounds
>> possible?
>>
>> I would appreciate any input,
>>
>> Ioan
>
>Dear Ioan :
>
>To me it sounds like copper plating problem. The surface of the base copper
>probably was not cleaned enough, it caused blisters. I think if you do a
tape
>test after copper plating, probably, copper plated will peel.
>
>Please correct me if I am wrong!!!
>
>Francis
>
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