Steve

This is incredible. Change your supplier as top priority :-)  Seriously, as the others
say, the "bubbles" are probably due to solvent/water entrapment in the track corners.
However, I see another problem which may/may not be related. Am I correct in thinking
that it has been hot and humid where you are, lately? If so, it would seem that there
has been hygroscopic contamination left on the board. On your first photo, see the
myriad white points between the tracks? This looks like vesication to me. The most
common cause is hygroscopic contamination (ionic or non-ionic) which pumps atmospheric
humidty across the mask layer (all polymers can allow humidity through). The osmotic
pressure rises until it actually lifts the mask off the surface, locally, forming a
vesicle or, if you like, a microblister (see my book for detailed explanation). This
could possibly be the cause of your bubbles along the track edges, as well, although
these seem rather gross: the photo I use to illustrate vesication also has bubbles
along some of the track edges, but the vesication between the tracks is on a similar
scale. Whatever, it is a totally unacceptable fault.

Brian

"Stephen R. Gregory" wrote:

> Hi all!
>
> We just got some boards in at receiving inspection that have thousands of
> little "bubbles" in the soldermask all over the boards...they seem to
> concentrate all along the edges of the features of the board. You can see
> pictures of it at:
>
> http://www.driveway.com/share?sid=e25a88c4.8e904&name=Pictures
>
> One picture is bubblemask.jpg, the other is bubblemask2.jpg...what would
> cause that? It's a LPI...don't know the brand name. I'm thinking that either
> the boards weren't dry or cleaned well prior to soldermasking them. I'm
> rejecting the boards of course...
>
> My freedrive is filling up fast with all the pictures of the "pretty boards"
> that we get from our vendors!!!
>
> -Steve Gregory-
>
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