From: Mayer, Mike (email@example.com)
Date: Thu Mar 09 2000 - 06:27:03 PST
Wire wrap was not just done by machine. As a student I wire wrapped hundreds
of multibus 1 boards for the University. We used electric wire-wrap guns.
This was early 1980's.
Mike Mayer Artesyn Communication Products, Inc
Senior Hardware Design Engineer Madison, WI
> -----Original Message-----
> From: Cusanelli, Tony [mailto:Tony_Cusanelli@mentorg.com]
> Sent: Thursday, March 09, 2000 5:08 AM
> To: firstname.lastname@example.org
> Subject: RE: [SI-LIST] : why .062?
> A few people asked for the "old guys" to comment on why
> boards are .062.
> Back in the dark ages (30 yrs ago) the boards I first
> designed were merely
> mechanical devices that supported parts. Connectivity was
> accomplished via
> wire-wrap. Parts were heavy and boards had to be thick
> enough to prevent
> breakage, but thin enough to carry. 1/16 inch became the
> right compromise
> and card guides, standard socket boards and chassis were all
> designed to fit
> that thickness.
> Even with today's lighter parts, tracks are thin and need
> some support.
> .032 boards are okay if they are small. Flexing and the pressure from
> connector insertion/extraction will fracture thin traces.
> PS - for you young guys - wire wrap was accomplished with a
> device similar
> to a hollow drill bit that would wrap 6-8 turns of 30 awg
> wire around a
> square or rectangular post. The edges would bite into the
> wire and make a
> gas-tight connection that was tested with a pull device
> (strain gauge). We
> had some PC boards, but they were mostly 2 and four layer.
> Draftsmen just
> could not lay out a board as fast as I could write a wirelist
> for the wiring
> Yes now I feel like a dinosaur.
> -----Original Message-----
> From: Alex Li [mailto:email@example.com]
> Sent: Monday, March 06, 2000 9:36 PM
> To: 'firstname.lastname@example.org'
> Subject: [SI-LIST] : different 4-layer board Stack up (S-P-G-S) ?
> Recently I saw a 4-layer mother board with 100 Mhz 128-bit
> memory bus.
> This board has unusual signal-power-ground-signal stack up.
> I talked to
> one of their engineer for this kind of arrangement. They
> said since most PC
> motherboard has several power plane split and on the top
> level there are a
> lot of components with pads. they think if they route all the
> 128-bit memory
> bus on the back and put it close to ground plane, they have
> much routing
> area and this will help to keep the signals clean.
> This is kind of new idea to me, does anyone see any
> drawback by this
> arrangement ? Will this decrease the decoupling caps performance ?
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