On Thu, 6 Nov 2003, yong zhu wrote:

> Dear All,
>
> My device is a thermal in-plane actuator made by MUMPs
> process. It moves mainly forward in-plane under
> applied voltage though a little downwards motion
> occurs. However, the weird thing is that after the
> wire bonding, the device only moves down. I have
> tested a bunch of devices, which all show this
> behavior. I donnot think stiction is the reason
> because stiction is also existing before the wire
> bonding. I am curious what's the cause and how to
> avoid this.
>
Greetings, Yong.

It's hard to say what's going on with this limited information. You need
to think about what is different after you wire bond the chip. For
example, is the chip in a different carrier after wire bonding?

Off the top of my head, and without knowing what this chip *looks* like, I
would say that this reads like an electrostatic effect. Is your substrate
grounded before and after wire-bonding, or does that change?

Just look at the chip. How is the chip different, how is the chip's
surroundings different? These are the sort of questions you need to ask
yourself.

> Many thanks,
>
> Yong
>
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