The easiest way to observe areas of possible stress in such a composite
system, is to illuminate with a polarised light source (s or p polarised
HeNe). Illuminate at an angle of about 30 degress to the surface normal, and
view the reflected light through a polariser. By orienting the polariser,
you will see modulations in the reflected light intensity, indicative of
residual stress in the system.

K. Cazzini (Ph.D)


----- Original Message -----
From: "li shifeng" 
To: 
Sent: Friday, January 25, 2002 9:35 PM
Subject: [mems-talk] any method to measure residul stress in bonding
membrane


> Hi, friendsI am interest to measure the residual stress in glass membrane
> after Si-Glass bonding. As i know, eventhough thermal coefficient is
> pretty closed between silicon and Preyx7740, there is some stress left
> after bonding. The residual stress affects membrane vibriation
> performance somehow.Anyone has done similar experiment before or has the
> same idea? maybe you can share some information. any information
> will appreciated. thanksshifeng
>
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