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Date: Mon, 16 Dec 1996 08:39:54 -0800
From: Steve Collins <<a href="/scripts/wa.exe?LOGON=A3%3Dind96%26B%3D--%26E%3D7bit%26L%3DTECHNET%26P%3D16824872%26T%3Dtext%252Fplain" target="_parent" >[log in to unmask]</a>>
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Organization: TSX Corporation
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	"RwF - ext. 355 - Pat Bailey" <<a href="/scripts/wa.exe?LOGON=A3%3Dind96%26B%3D--%26E%3D7bit%26L%3DTECHNET%26P%3D16824872%26T%3Dtext%252Fplain" target="_parent" >[log in to unmask]</a>>
Subject: Re: CEM-3 vs. FR-4
References: <<a href="/scripts/wa.exe?LOGON=A3%3Dind96%26B%3D--%26E%3D7bit%26L%3DTECHNET%26P%3D16824872%26T%3Dtext%252Fplain" target="_parent" >[log in to unmask]</a>>
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RwF - ext. 355 - Pat Bailey wrote:
> 
> Are there any significant differences/concerns in fabrication, assembly, or
> long term reliability when comparing CEM-3 to FR-4 for double sided PTH
> boards?  Is it compatible with carbon direct metallization?  In what
> product applications is CEM-3 typically used for double sided PTH boards?
>  From what I've been able to gather, it is used quite a bit in Asia but not
> in North America.  Why (availability, end product application/reliability
> reqiuirements, no significant cost advantage...)?
> 
> Regards,
> 
> Pat Bailey
> Zytec Corporation

Pat while in another life we used CEM-3 quite extensivly. The main
problem we has was with Bow & Twist. The material moved around so much
that we ended up switching to FR-4. The movement was around .001 per
linear inch. What our vendors ended up doing was trying to predict the
movement and adjust the drill, Rout & A/W to compensate. An after
thought I have had recently was if we were to have been able to use an
OSP on our boards in our production environment would that have made the
material more stable. We did try an OSP but not for this reason and it
failed in our application using "no clean" assembly techniques.

Steve Collins
PCB Design Supervisor
TSX Corporation
El Paso, TX
Ph: (800) 351-2345
Fax: (915) 543-4898
email: <a href="/scripts/wa.exe?LOGON=A3%3Dind96%26B%3D--%26E%3D7bit%26L%3DTECHNET%26P%3D16824872%26T%3Dtext%252Fplain" target="_parent" >[log in to unmask]</a>


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