What's wrong with my amp in EaglePCB?

[Spasticteapot]

I've got a rather peculiar problem - while the BUF634 in the library shows up all nice and neat, the one on my PCB has the pads so close together that they're shorting out. Does anyone know what could be causing this?
Here's a picture:


You can download the files here:
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[jaycee]

The problem is that the "TO220-5G" package definition in the "burr-brown" library is crap. 1.1mm drill holes with a 1.27mm diameter pad - EAGLE correctly realises that this will not work, and enlarges the pads.

The package TI describe for the BUF634T doesnt really make for leaving much clearance between the pins. This is fine for a professional PCB manufacturer, but too tight for hobbyist development.

What I would do here is make a package variant of the BUF634 device that uses the "TO220-5" package that has staggered leads. You will need to bend the leads yourself, but your PCB will be easier to make. A similar chip, Linear Technology's LT1010, has just this configuration.

[Greg Erskine]

hi teapot,

I know whats happening but I don't know why? I'll be very interested when someone works it out.

The pads are resizing as if they were set to auto. I don't know why it is ignoring the real pad size defined in the library.

Look at Tools > DRC > Restring. Pads change size depending on what .drc file is being used.

regards

[Spasticteapot]

I'll admit I'm quite stumped. I'd use the staggered package, but my buffers wouldn't fit (they're actually LME49600s - the pins are too short.)

[nigelwright7557]

Originally Posted by jaycee

- EAGLE correctly realises that this will not work, and enlarges the pads.
.

Thats scary, software that thinks for itself !
I prefer my software to do what I want, not what it thinks is right.