Ditto,
with the requirements of EMC proofing boards becoming more and more
prevalent, placing anything other than the crystals reference ground
underneath it can surely allow some unwanted cross coupling of the wobbly
signal to others?

Especially so if its very very wobbly (high frequency)..
That with the chance that a poor mask could permit a metal can to touch
tracks make the area that a crystal goes in a keep out area for everything
else.

Unless of course you cant get that last track in without adding another
layer
and then - well good intentions go out of the window while the price comes
through the door.

Matthew Lamkin.

> -----Original Message-----
> From: Kitty Hines [SMTP:[log in to unmask]]
> Sent: Monday, May 06, 2002 3:25 PM
> To:   [log in to unmask]
> Subject:      Re: [DC] Clearin' Crystals
>
> I've always been told to clear planes and traces underneath crystals.
> The higher the frequency the more sensitive the circuit.
>
> -----Original Message-----
> From: Jack C. Olson [mailto:[log in to unmask]]
> Sent: Friday, May 03, 2002 5:36 PM
> To: [log in to unmask]
> Subject: [DC] Clearin' Crystals
>
>
> Informal Poll:
>
> How many of you prevent traces and clear planes underneath crystals?
> I've seen it both ways, and never heard any science one way or the
> other.
> I've also never heard of any problems with a design that had traces
> passing through under the body of a crystal, Have you?
>
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