Can someone explain why a 3 layer board would warp? It seems that the
structure would be balanced around the middle if it was 1) ground 2) signal
3) ground. I don't fully understand why an odd number of layers warps.
Thanks,
Matt
Matthew Sanders
PWB Procurement Engineer, Trimble Navigation Limited
[log in to unmask]
Phone: (408) 481-7817
Fax: (408) 481-8590
> -----Original Message-----
> From: Charles Barker [SMTP:[log in to unmask]]
> Sent: Saturday, July 04, 1998 9:04 AM
> To: [log in to unmask]
> Subject: Re: [TN] Warpage
>
> Dear L. Ramesh,
> Warpage can be caused by many different things. One frequent cause that I
> have run into is poor board design. It is important to keep the amount of
> copper on each layer balanced about the middle of the board when viewed
> from the edge. As an example, a four layer board with plane layer(s)
> should
> be:
>
> Layer one, signal
> Layer two, plane layer (Power of Ground)
> ========================================= Middle of Board
> Layer three, plane layer (Ground or Power)
> Layer four, signal
>
> If the circuitry NEEDS only ONE plane layer (three layer board), duplicate
> that layer to provide the necessary balance (make it four layers).
> There should always be an even number of layers in a multi-layer board.
>
> There can also be other issues such as the grain direction, size and
> structure of the pre-preg material. One of the board fabricators on
> TechNet
> will have to explain those issues to you. Other causes could be how the
> board is cooled after lamination.
>
> I hope this helps.
>
> Charlie B.
>
>
>
> Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please
> respond
> to "L. RAMESH" <[log in to unmask]>
>
> To: [log in to unmask]
> cc: (bcc: Charles Barker/US/I-O INC)
> Subject: [TN] Warpage
>
>
>
>
> Dear Technetters,
> I would like to know the possible causes for warpage and its control. All
> suggestions is gratefully acknowledged.
> Regards,
>
> L. RAMESH, Tel: +91-8221-26618, 26619,
> Indal Electronics Ltd., 26375, 26584 Extn: 345
> No.12 A, Industrial Area, Fax: +91-8221-26641
> Nanjanagud 571 301, email: [log in to unmask]
> District Mysore, INDIA. web site:www.indalpcb.com
>
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