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August 2005

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Subject:
Re: Spam: [TN] GaAs and BeO Coefficient of Therma Expansion curve
From:
"Creswick, Steven" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Creswick, Steven
Date:
Mon, 29 Aug 2005 14:15:35 -0400
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text/plain
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Sundog,

I don't have any curves but consider CTE of BeO to be 7.2-7.6 ppm in the range of 25-300°C [based on data from 4 sources], whereas I only have one data point for GaAs in the 25-300°C range and that is 6.5 ppm

Since the AuSn eutectic is right at 280°C [or maybe 282°C as I have seen in some places], you should be placing the device under compression as the substrate cools down.  This is better than the alternative!

Pretty funky aspect ratio on the chip!

Like to know if anyone else has better values so as to update my database...

Steve Creswick - Gentex Corporation


-----Original Message-----
From: Sundog [mailto:[log in to unmask]]
Sent: Monday, August 29, 2005 1:34 PM
To: [log in to unmask]
Subject: Spam: [TN] GaAs and BeO Coefficient of Therma Expansion curve


Dear all,

Does anyone has a GaAs CTE curve (vs. temperature). I am trying to solder a
10mmx1mmx0.14mm GaAs die to a BeO substrate with AuSn solder. I am not
quite sure if there CTE is matched well enough.


Thanks
Sundog

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