[SI-LIST] Re: Need advice on basic 6-layer stackup - board warpage

Graham, I would be quite hesitant to leave a solid plane unbalanced.  Since 
you have options that will not otherwise impair your design, I would employ 
them.

Good luck.

Steve
At 01:18 AM 4/27/2005 +0000, Graham Davies wrote:

>--- In si-list@xxxxxxxxxxxxxxx, "Sol Tatlow" <Sol.Tatlow@xxxx> wrote:
>
> > Steve is absolutely right to
> > advise against non-symmetrical
> > board stacks, and here's an
> > example why: ...
>
>I'm soaking this stuff up. Straight as a banana. Got it.
>
> > ... ask your PCB fabricator ...
>
>Actually, now you mention it, they came up with our new stackup. We
>(I say "we", but this is before I joined) specified a stackup that is
>almost as laughable as your banana boards. They threw it in the trash
>and made a suggestion which we accepted. Note that the entire board
>design was done assuming one stackup but when the board house needed
>to use a completely different one it was approved without pause. See
>what I'm up against?
>
> > ... perhaps ask your populator
> > as well ...
>
>Too small and not enough experience. We're moving elsewhere. As far
>as I can see, the boards with the new stackup are acceptably flat.
>
> > ... type of soldering ...
>
>It's reflow.
>
> > ... lead-free soldering ...
>
>Oh, boy.
>
>Graham.
>
>
>
>
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