Re: [SI-LIST] : CDM and HDM models of

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From: D. C. Sessions ([email protected])
Date: Mon Mar 20 2000 - 07:00:42 PST


Jan Vercammen wrote:
>
> hello,
>
> I have a question that concerns electrostatic discharge (ESD). I am asked to give ESD
> specs for a thermal printhead. The printhead is an assembly of a ceramic carrier and
> a large number of silicon chips. We have asked for a data interface based on CMOS LVDS
> (low voltage differential switching).
>
> I have no idea of the CMOS process, do I think it is not that advanced. Let us assume
> between 1.25 and 0.5micron.

Unlikely. Economics alone are making anything over 500 nm pretty scarce;
350 nm is much more common and the sweet spot is moving down fast.

> (1) Which figures should I specify for CDM (1R-200pf) and HBM (1.5kR-100pf)?
>
> (2) I have found figures of 1500V for HBM and 500V for CDM. Are these numbers acceptable,
> too high or too low?

500 v CDM is pretty standard. This is your automated-assembly condition and
most assembly equipment is safe for 500 v HBM parts. More is useless, less is
dangerous.

HBM is more variable. 2000 v is pretty standard for stuff that will be handled
with moderate care, but printheads are likely to be abused in ways that more
'internal' parts won't be. On the other hand, if the contacts are reasonably
well protected (ie, almost anything is likely to contact ground first) then
1500 v might be acceptable. You really need to know the application.

-- 
D. C. Sessions
[email protected]

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