Another thing to consider is that TQFP does not specify package size or pin spacing. The pin spacing can be anywhere from .4mm to 1mm and the package size will be different accordingly. So you must check all the dimensions before using a package! I think there should really be a set of packages with something in the name indicating pin spacings - such as TQFP64_.4, TQFP64_.5 and so on.
Moses On Sat, 2010-02-06 at 11:50 -0600, Karl Schmidt wrote: > Stephrac74 wrote: > > I’ve not checked before drawing the PCB that the module was ok…. And what a > > mistake ! > > > I've run into the same problem on high end commercial packages - there is a > high rate of errors in > the parts libs. I almost always spend half my time defining new parts - there > are several reasons: > > 1 - Most large chip library parts don't have the pin placement organized > logically. schematics > ought to convey information in an understandable form - not just hacked > together connections. > > 2 - I always bring out a real ground and power pin - using auto connect > sounds like a time saver - > but real circuit boards need ground and power nets that are designed to > minimize ground noise. Even > on multi layer boards with dedicated power layers there becomes the issue of > separating analog and > digital grounds - knowing how to split ground and power plans for A/D > converter areas and high gain > input sections is a must. > > 3 - added fields that make procurement, ECO, multi source etc. - unless you > hate the buyer. > > This is tedious time consuming work - but it pays in the end. My hunch is > that open-libraries will > end up with lower error rates - should be a field that says who (email) is > the maintainer of a > library part so corrections can be sent off. > > > -------------------------------------------------------------------------------- > Karl Schmidt EMail k...@xtronics.com > Transtronics, Inc. WEB http://xtronics.com > 3209 West 9th Street Ph (785) 841-3089 > Lawrence, KS 66049 FAX (785) 841-0434 > > Let us live so that when we come to die even the undertaker will be sorry. > -- Mark Twain >
