Hi Yuan!

Their explanations are correct.
Regards,
Motoyo Wajima
Hitachi, Ltd.(Japan)


LI YUAN  $B$5$s$O=q$-$^$7$? (B:
>Does anyone know the CTE above Tg?
>
>My supplier told me that CTEs (in plane)  of HL-832 are as following:
>
>14-16 ppm @ 60-120C
>9.5 ppm @ 120-240C
>5 ppm @ 240-280C
>
>I am very supprised that CTE2 is lower than CTE1. Their explanations are
>as follows:
>
>1)  Regarding alpha2
>As for the Z-direction of CTE, alpha2 is higher than alpha1,
>but XY direction of CTE is different.
>
>Of course alpha2 of resin is higher than alpha1.  On the other
>hand, glass fabric has no Tg and no alpha2.  It's CTE is constant
>--  5ppm/k --- under 800 degC.
>
>Under Tg, resin is hard and solid, so resin's thermal expansion
>(60-80 ppm/k) is stronger than glass fabric's resistance (5ppm/k)
>against resin expansion.
>
>Over Tg, resin is soft, so glass fabric's resistance is stronger than
>resin's expansion.  Therefore, alpha2 of XY is nearly glass fabric's
>CTE  --- around 5ppm/k.
>
>What are your comments? I still think CTE2 (above Tg) should be much
>higher than CTE1 (below Tg), that's what is claimed in many literatures.
>
>Thanks,
>
>
>Yuan Li
>
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***********************************************
Motoyo Wajima
Enterprise Server Division,Hitachi,Ltd.
1 Horiyamashita
Hadano-shi,Kanagawa-ken,259-13 Japan
E-mail:[log in to unmask]
Fax:+81-463-88-2935
***********************************************

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