Earl,

Your pictures are up! Go to:

http://www.stevezeva.homestead.com

-Steve Gregory-


> Seth and other fine folks,
>
> I do a lot of work in the R/F MLB world. Who doesn't. In this regard, I
> asked Steve if he'd kindly post two x-section images. Both show blind vias
> not of the micro type. One is shown from a bucket shop not knowing what they
> had done really was pretty good but for obvious plating problems.
>
> The first image shows a "normal" blind via that has been plated over. The
> fill resin was formed in the sequential lamination process. I try to ignore
> all the 7628 material but for its ability to fill the hole to the top with
> resin. Then, the hole/resin fill was plated over. The hole diameter, as I
> recal, was about ten mils. Therefore, it was producible through "norman"
> drilling processes and should have shown no ill effects as the poor plating
> shown. What's really important is the plating over the top. It is robust and
> shows little depression, though exagerated by the micro section, at about a
> mil or so. I rather like it as it is a near perfect depression and suits
> BGA's very well though they need little help self aligning.
>
> The second (color) image shows a "normal" drilled blind via. I think Proto
> Engineering provided this section (how are my latest boards coming?). What's
> interesting here is the possible plating over capability. If filled
> properly, like Sanmina's tech center process and others, it would be plated
> over without much notice.
>