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February 2004

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Wed, 4 Feb 2004 19:12:53 -0800
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----- Original Message -----
From: "Mike McMonagle" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, February 04, 2004 12:29 PM
Subject: [TN] 0805 Pad Geometry


> Looking for feedback on what pad geometries are being used these days
> for standard 0805 chips. We are primarily a high-rel, low volume high
> temp alloy shop, but have recently pulled in a standard Sn63 board in
> volume that the customer is looking for a little layout assistance on.
> Pad dimensions are way too large and pad-to-pad spacing too tight,
> contributing to big fillets and squeeze balls at the component edges. It
> could be worked through aperture changes in the stencil, but the fab is
> being spun for another reason anyway so now's a good time to fix 'em up.
> Seems that almost every component manufacturer is calling out there own
> pad preferences, many of which are contradictory to IPC design
> guidelines. Also, any new comments on the pros and cons of using pads
> that are slimmer than the termination width of the component? TIA for
> the insights....
>
> Mike
>

Mike,
I looked at the 0805 part in my library and it has 50mil X 40mil pads spaced
80mil apart (center to center).  Those measurements are X,Y if the part is
viewed vertically.  I don't think I tailor that part very often, and it has
always worked without any incidents ever being reported to me.
Good luck.
Richard

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