Abdul-Rahman
    Yes I have seen an inner plane layer come all the way out to an edge.
    The design was supposed to be "better for RF", but made no difference
    in board performance. The two outside layers were plated aound the edge
    and shorted ( on purpose ) to the inner layer. This was a nightmare to
    build and cost "extra".
    The same performance was achieved by placing a row of vias 100 mils
    from the edge on a "regular" board, at a much lower cost.

Bob Fearon


Abd ul-Rahman Lomax wrote:

> At 05:32 PM 11/8/01 -0500, Mike Reagan wrote:
>
> >you scare me man   thinking that you are design aircraft components and dont
> >know how to use the progam     I think you better fligt test it
>
> Knowing how to use the program is a convenience, not a necessity. The
> necessity is to know how to inspect the gerbers or films and the board itself.
>
> Let me put it this way. If I want reliability of a pcb, I will prefer it to
> be designed by someone who knows electronics and reliability issues, but
> who is a beginner with a piece of software he uses, than by one for whom
> the reverse is true.
>
> (I don't think Mr. Robison is designing "aircraft components." Last we
> spoke, he was designing equipment that might fly *on* a plane, but it does
> not *fly* the plane. If one of his boards fails, if I am correct, it will
> be a nuisance, not a disaster.)
>
> In my experience, boards for hi-rel usage (for me, it has been space
> flight) are reviewed through several different stages, at least. While it
> is obviously best and safest to get the board right in the first place
> (after all, there is a statistical possibility that the later safeguards
> could all fail), the knowledge that negative planes should not go to the
> board edge is widespread. As I mentioned previously, most board houses,
> perhaps all, will already create an edge clearance if you don't put one
> there and you don't clearly specify that you *don't* want one. They have
> been dealing with gerbers with no edge clearance for years, but they have
> probably never encountered a request for planes to go to the edge.
>
> Has anyone reading this received fabricated boards with no inner plane
> clearance? Was it from an established fabricator? (I'd be surprised if it
> *never* happened, but I would also be surprised if it was at all common.)
>
> [EMAIL PROTECTED]
> Abdulrahman Lomax
> Easthampton, Massachusetts USA

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