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Pad Size for TQFP Package??

Hi all,

I'm designing a PCB for a PIC18F8722 which has a TQFP 80 package. This is the PCB I've designed for an SMT type device and I was wondering what the standard pad size is for this? From what I've seen on the web, they look rectangular, but I'm not sure of the dimensions.

Also, does anyone know of free software capable of laying out a PCB (could be manually and not through schematic capture) while also being able to generate the gerber files. I know there are a lot of vendors out there which let you download their software if you pay for them to manufacture your PCBs...but I already have someone for this.

Thanks, weg22

Reply to
weg22
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I'd read the end bit of the datasheet.

Fuck Off

DNA

Reply to
Genome

For the PCB layout check the data sheet as Genome says. If Microchip doesn't put it on their datasheets there'll be a separate sheet for the package.

Eagle is a good package. Their free version will let you do small (3"x4") two-layer boards. It includes schematic capture, layout and plot to Gerber.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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"Applied Control Theory for Embedded Systems" came out in April.
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Reply to
Tim Wescott

Try: gschem

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pcb
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gsch2pcb will convert your gschem schematics into pcb format. QFP packages etc.. are included. Just specify footprint=QFP80 (or whatever) in your schematic attributes. And verify correct output in pcb. 'pcb' will make your gerber files. And let you autoroute or manually adjust layout.

Reply to
pbdelete

I've tried it and I cannot recommend it. Gschem is quite good, but it is very cumbersome to work with. PCB is almost completely useless for what it is meant to do. The problem with pcb is that it doesn't assign netnames to a trace. This seems trivial, but it causes major problems when editing the PCB. Also the copper pours are a nightmare. Another problem with PCB is that it automatically erases the silkscreen when it is over pads. Last but not least, most of the standard SMT footprints are wrong.

If you want something decent, get Eagle like someone else already suggested.

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Reply to nico@nctdevpuntnl (punt=.)
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Reply to
Nico Coesel

If it run on unix too it would be even better..

Reply to
pbdelete

Get Kicad

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100% free and runs on Windows & Linux. Or FreePCB
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together with TinyCAD
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--DF

Reply to
Deefoo

For getting footprint information,

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offers a free footprint viewer called LP Viewer. Lots of footprints for ho-hum parts to the latest icky packaging technology. On the right side of their web page, look for "featured items". You may want to load in a few more libraries from their "library documentation" area.

Usually, the footprint info is in the data sheet or the manufacturer has an area in their web site that has this information.

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Mark
Reply to
qrk

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