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QFP footprint -extended outside pad?

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#65035

QFP footprint -extended outside pad? | 15 September, 2011

G'day folks - haven't been around for some time but still soldering on. Question for y'all.

One of my design engineers has shown me a Creative PCI audio card with a TQFP48 attached. 0.4mm pitch. Let's say the pin width is 0.2mm and the pad design has the pads at 0.2mm width also. On each of the 8 outside pads the pad is wider to the "outside" of the pin. Let's guess at 0.05mm or less.

Does anyone know the reasoning behind this? There is a very crude drawing attached to explain. I removed a few cogs from the Spirograph to do the drawing.

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