Did you attempt an adhesion test of the mask in that area?

Might be poor solder mask coverage due to contaminates of some type...the
heat from the soldering iron causing it to separate from the copper or
glass...

Franklin


----- Original Message -----
From: "Lum Wee Mei" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, January 06, 2004 1:45 AM
Subject: [TN] Solder Mask Defects - What casue it.


> Hello,
>
> I have asked Steve to download the picture at his site. Once it ready,
> can someone take a look and give me your opinion what is the likely cause.
>
> Background : The board was partially mounted previously.  It come back
> to mount the remaining 6 chips. The board was washed as per normal with
> Ensolv and assembled immediately.  As the operator solder the chip, she
> noticed scale-like defects appearing on the soldemask around the whole
> stretch of the solder pads. The defects are more prominent on the left
> side compare to right of the chip. This is repeated for the rest of the
> 5 chips.
>
> Being naughty, she touched the board surface with the soldering iron tip
> and found on the same spot the same defect appearing.
>
> One more information : defects found on these 2 boards have a much more
> rough surface compare to other pieces within the same batch.
>
> How the information is sufficent for you to provide opinions.
>
> Thanks and regards,
> Wee Mei
>
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