Pad Size for TQFP Package??

[[email protected]]

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

 

[Genome]

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.

Thanks,
weg22

I'd read the end bit of the datasheet.

**** Off

DNA

 

[Tim Wescott]

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

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

Posting from Google? See http://cfaj.freeshell.org/google/

"Applied Control Theory for Embedded Systems" came out in April.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

[[email protected]]

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.

Try:
gschem http://www.geda.seul.org/
pcb http://pcb.sourceforge.net/

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.

 

[Nico Coesel]

Try:
gschem http://www.geda.seul.org/
pcb http://pcb.sourceforge.net/

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.

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.

 

[[email protected]]

[email protected] wrote:

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.

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

 

[Deefoo]

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

Get Kicad (http://www.lis.inpg.fr/realise_au_lis/kicad/), 100% free and runs
on Windows & Linux.
Or FreePCB (http://www.freepcb.com/) together with TinyCAD
(http://tinycad.sourceforge.net/)

--DF

 

[qrk]

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

For getting footprint information, http://www.pcblibraries.com/ 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.