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September 2004

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Subject:
From:
"Brooks,Bill" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Brooks,Bill
Date:
Tue, 21 Sep 2004 15:10:58 -0700
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Chris' e-mail prompted this inquiry...

I wish to ask a question regarding punching glass laminates.
Suppose that I needed to make a million PCB's but they were not possible to
do any other way than with multi-layer Fr4 type materials. Would you be
stuck with routing the board edges only or is there a more cost effective
solution?

Punching in my experience was always a tool life issue due to the abrasive
nature of the fiberglass. I have done many multi board panels in my career,
including punch and return FR4, CEM1, and 'cracker', or scored board edge
methods.   I am wondering if the life of the punch and die tool could be
extended by precutting the fiberglass cloth in a pattern that left a
'fiberglass free' void where the punch would trim the board leaving a web
much like the typical type we see routed on multiple board panels? The punch
would only be cutting epoxy then. I wonder if that precutting of the cloth
process would significantly increase the cost of the cloth? What about
alignment issues etc....

 Many of you make your living solving problems like this... what suggestions
would you have to solve this problem? Has anyone tried this?

Thanks in advance...

Bill Brooks
PCB Design Engineer , C.I.D., C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
http://pcbwizards.com

-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Tuesday, September 21, 2004 1:31 PM
To: [log in to unmask]
Subject: [DC] punching 4 layer board

Hi All-
I need to know if anyone is getting multi-layer boards with punched
features today. If so, some feedback on the quality. One of our assembly
houses wants to move some high volume boards to a new supplier who has
already tooled up to punch the arrays.

We've used millions and millions of punched CEM1 PCB's and a few million
punched FR4 2 sided. Never had any problems attributed to the punch vs.
routing process.

Need to know if 4 or 6 layer FR4 is another story or no different than 2
sided FR4.

I'm not talking about plated through features, just the board outline (many
boards in an array).

I asked this before and got a little feedback; at the time there was no
feedback from anyone doing it. It seems some of these low cost Chinese
houses do nothing else. Has anyone else run into this?

Thanks in advance,
-Chris
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