controll the individual lamination and etch processes in the individual
facilities.
Bob
-----Original Message-----
From: Barbara Burcham <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Thursday, February 10, 2000 5:00 PM
Subject: Re: [TN] PREPREG AGAIN
>WOW! That is all well and good....but what do you do to acheive controlled
>impedence?
>
>Barbara J. Burcham, CID
>PCB Designer
>Fairfield Industries
>Sugar Land, TX 77478
>281-275-7687 Work
>281-275-7550 Fax
>[log in to unmask]
>
>
>-----Original Message-----
>From: Glenn Pelkey [mailto:[log in to unmask]]
>Sent: Thursday, February 10, 2000 3:53 PM
>To: [log in to unmask]
>Subject: Re: [TN] PREPREG AGAIN
>
>
>Hi all,
>
> I worked for a laminate manufacturer about four years ago. So,
>things
>may have changed, but here's how we addressed this.
>
> The issues pointed out are correct. There were too many factors in
>lamination to get a good, consistent predictor at the PCB fabricator site
by
>testing at the laminate mfr. When you multiply press type, pressure, heat
>profile, board construction, vacuum, load, lag, humidity, age of prepreg,
>and
>multiply that by the number of customers, it just gets even harder to
>specify
>a number. This is especially true when you're producing what's considered
a
>"Standard" product. So, pressed thickness was never specified, but it was
>listed with a "Typical" value range. We also performed "Scaled Flow
>Thickness" measurements periodically which was mentioned in a previous
post.
>(PC-TM-650, Method 2.4.38) Sometimes, the results from this test would
>provide a starting point or early indicator of performance, but still no
>guarantee.
>
> The best bet was for the PCB shop to develop a standard panel which
>could be run through the process and the results measured. If you had some
>correlation to the other factors mentioned, you'd have a better guess at
the
>final thickness.
>
>Glenn
>
>P.S. Let me know if you need the internet links to the laminate suppliers.
>There used to be a couple listening to the Technet.
>
>Brunker Ed <[log in to unmask]> Wrote:
>|
>| Sorry guys,
>| I'm still wrestling with this one.
>| Can you give me the thickness of 1080 X 2 after pressing.
>| Can we work through the reasons for two suppliers giving different
results
>| for the same prepreg bearing in mind that not all manufacturers are in
the
>| western world.
>| Does the pressing process have much impact on finished thickness?
>| Are there any standards with which to control prepreg production?
>| Regards
>| Edward Brunker
>
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