Used to buzz WAY too often, that's why I haven't buzzed in 'bout 15 years :)
Durn bees :)
--
George Patrick
Tektronix, Inc.
Central Engineering, PCB Design Group
P.O. Box 500, M/S 39-512
Beaverton, OR 97077-0001
Phone: 503-627-5272 Fax: 503-627-5587
http://www.tektronix.com <http://www.tektronix.com>
http://www.pcb-designer.com
It's my opinion, not Tektronix'
-----Original Message-----
From: Jay DeKing [mailto:[log in to unmask]]
Sent: Thursday, December 11, 2003 21:47 PM
To: [log in to unmask]
Subject: [DC] OT: Re: [DC] Manufacture adjusting Gerber's
This post is definitely a bit off topic, but I guess I'm spoiled from
the PADS listserver ... which is notoriously off-topic on a regular
basis ...
I think that I should re-subscribe to this list at my work e-mail
address, so I can read it during the day. I always seem to finally get
around to reading the DC list at about 11 or 12 pm, when I have a bit of
a buzz on and am getting ready for bed. It just doesn't do much good at
that point ;-) I'm scanning through it right now, knowing that I should
understand what's going on, but it just isn't sinking in!
Sorry for the OT post. This list is always so professional, and I like
it that way!
I can't believe that 10 years ago I used to work with a buzz on every
day. At the time, I was *sure* that it gave me a creative edge. Ugh.
(By the way, if anybody wants to contribute any comments about that,
please send to me off-list. I don't want to contaminate DC with that
kind of thread. One OT post is enough.)
Jay
On Wed, 2003-12-10 at 11:39, Kowalewski, Andy wrote:
> It's to do with the plating of the barrel in a multilayer board.
>
> When the hole is drilled, the external surfaces have complete copper
> coverage and so the annular ring isn't evident until after imaging and
> etching. Hence you can add the thickness of the plating to the pad size
> for an annular ring requirement.
>
> On the inner layers, imaging and etching have already been completed so
> when the hole is drilled, it needs to 'see' enough copper around the
> hole so that the plating of the barrel makes good contact to the
> innerlayer pad. That hole size is the drilled hole, but the final hole
> size is the one specified by the designer and relies on an oversize
> drilled hole to be plated up. So the annular ring is specified 'worst
> case', which is before plating.
>
>
> Andy K.
> Sychip Inc
> Office (972) 202 8852
>
> -----Original Message-----
> From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Stan
> Radzio
> Sent: Wednesday, December 10, 2003 10:34 AM
> To: [log in to unmask]
> Subject: Re: [DC] Manufacture adjusting Gerber's
>
> Gary,
> I was following you right up to the point where you said "for
> inner layers". I don't mind looking like an idiot asking questions that
> are obvious to everyone else. Could you explain why you are using the
> drill hole size versus the finished hole size on inner versus outer
> layers? Said another way: what is the manufacturing process that you
> are accommodating with this design decision?
>
> Thanks,
> -Stan
>
>
> -----Original Message-----
> From: Gary Ferrari [mailto:[log in to unmask]]
> Sent: Tuesday, December 09, 2003 5:12 PM
> To: [log in to unmask]
> Subject: Re: [DC] Manufacture adjusting Gerber's
>
>
> Ted,
>
> The board fabricator always drills with a larger drill bit to compensate
> for shrinkage of the laminate. This is why the designer uses the drilled
> hole size when calculating lands for inner layers. The finished hole
> size is used for calculating outer layer land sizes.
>
> The board fabricator is not requred to automatically adjust
> inappropriate spacing. They usually will contact the designer and
> explain the problem. That is, if you use a decent board fabricator.
>
> Regards,
>
> Gary
>
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"Whether it's Osama bin Laden, Saddam Hussein or Kim Jong Il, much of
today's news is dominated by pricks." - Jon Stewart, "The Daily Show"
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