Mark

Which CTE are you interested in (X/Y or Z) and over which temperature range?
The temperature range is especially important for the Z-axis CTE.  I've
looked into this over the last few years because I was finding seemingly
conflicting information.  I found some FR4 materials with published Z-axis
CTE values of approximately 75 ppm/C and others at 175 ppm/C.  This didn't
make sense until I started looking at the range of temperatures that were
used in the test.  If testing is limited to below the Tg of the resin
system, the CTE will be 75ppm/C or less.  If the temperature range starts
below and goes above the Tg values will be 150 ppm/C or higher.  Z-axis CTE
for FR4 above Tg may be as high as 300ppm/C.

I hope this helps.

> ----------
> From:         Mark Gilbert[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;Mark Gilbert
> Sent:         Thursday, January 25, 2001 1:18 PM
> To:   [log in to unmask]
> Subject:      [TN] TCE for FR-4
>
> Does anyone know the thermal coefficient of expansion for FR-4 offhand?
>
> Best Regards,
> Mark Gilbert, Product Engineer
> FOX Electronics
> For Frequency Control Solutions. . . Fast:
> 1-888-GET2FOX, ext. 2289
> Direct Line: 941-690-2289
> Fax: 941-693-1554
>
> http://www.foxonline.com/
>
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