Testing done at Circo Craft indicates excellent results of CEM3 product
when compared to FR4. This includes not only analysis of manufacturing
process compatability and product acceptability, but also reliability
testing and assessment. The material works well. It's only drawback is a
reduced flexural strength which will need attention when dealing with heavy
component loadings and/or V-groove or breakaway physical dimensions. As
noted in some of the attached postings, there may be differences in each
manufacturers' process and/or constructions which could explain varying
material characteristics.

Dave Rooke
Circo Craft - Pointe Claire

________________________________________________________

>     Just one note of caution when evaluating CEM3 material.  This material 
>     is seen to differ considerably in its mechanical characteristics from 
>     vendor to vendor.  Some vendors in the U.S. like GE and Allied signal 
>     have CEM3 which is much different from for instance, Nanya which is an 
>     Asian supplier.  CEM3 is typically used in double sided applications.  
>     It is much better for punching than FR-4, it is weaker mechanically, 
>     will warp more through the reflow or wave solder.  Price is typically  
>     8% to 10% raw material cost savings than FR-4.  Is largely used in 
>     Japan.
>     
>     Regards:
>     
>     Steve O'Hara
>     [log in to unmask]
>
>
>______________________________ Reply Separator
_________________________________

>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
______________________________ Reply Separator _________________________________

Differences between CEM3 & FR4 on doublesided boards.

Close but no cigar. Expect more through hole plating & assembly problems with
CEM3 & more debris in plating tanks. Might be cost effective if yields are
acceptable to you.


Tom Waznis
______________________________ Reply Separator _________________________________

>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
____________________ Reply Separator (original question) _______________________

>> 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
>     

>El Paso, TX
>Ph: (800) 351-2345
>Fax: (915) 543-4898
>email: [log in to unmask]
>

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