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Subject: Re: p.c.b forum

Date: 05/04/00 at 1:51 PM
Posted by: John W. Childers
E-mail: jwchilders@goldengategraphics.com
Message Posted:

In Reply to: Re: p.c.b forum posted by shoshi on 05/04/00 at 6:05 AM:

You're welcome!
>Do you use a lot the IPC standard...... I would never finish a PCB if I had to use every thing in there.
My approach to the IPC standard: I use it, but indirectly. The board houses spend a lot of time finding out how to comply with IPC. By spending my time talking to the board house CAM engineers and really finding out what is needed and wanted by them I make my designs manufacturable to IPC standards. A benefit of this approach: I get referrals from board houses, because I do, produce and/or present what is needed and wanted.

>Do you manufacture in the U.S.A or Far east?
So far, only in the US that I know of. As a design service bureau, I don't always know where the boards are being manufactured.

>I found it interesting about enlarging the via's for the current ..
>have you a chart for what current what width of track to use ?

Yes. UL (Underwriters' Laboratory) produces a graph for this. Unfortunately, I don't know where to get an online copy. Go to a big library and ask for UL specifications. There are also similar charts for high voltage, called "creepage distance".

>Via's I use 12mills hole with 20 0r 22 pad.
I've used a lot of that size via too. But I still try to use something larger for better manufacturability. Most board houses would want a larger annular ring than 4 to 5 mils, as in your example. It is a must to work closely with your board houses and give them what they want. They will happily tell you how to make your designs more manufacturable and thus reduce costs.


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