Jim,

You should know better than to offer anything free to this Technet crowd.  I
would also appreciate a fax of your chart.  thanks.

Ralph Vaughan
Boeing
Fax 770 497-5555

> ----------
> From:         James R. Paulus[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;[log in to unmask]
> Sent:         Wednesday, October 21, 1998 11:13 AM
> To:   [log in to unmask]
> Subject:      Re: [TN] FR4 thermal expansion
>
> I have a comprehensive chart which I can fax you, if you want to provide
> the
> phone #.
> Generally, Z-axis is 60 to 80 ppm (or microinches/inch/C), X is 17-20 ppm,
> and
> Y is 15 to 18 ppm.  Lots of variables however:
> a.  These values are for a temp ramp up to the Tg, which is 135C typically
> for
> FR4.
> b.  Remember that FR4 today can be a material with a Tg as high as 180C.
> Higher Tg FR4's tend to exhibit a slightly lower Z-expansion below the Tg
> than
> 135C types.
> c.  Z-axis is particularly affected by resin:glass ratio.  Higher Resin
> content means greater expansion, which has to be considered in high layer
> count designs.
> d.  Above the Tg,  the X and Y movements get squirrelly because the
> softened
> resin allows the glass fabric to pull back against the expanding matrix,
> resulting in much lower values.
> jimpaulus
>
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