PCB footprint documentation

[claessens]

I'm looking at PCB footprints for design. Component manufacturers describe well their dimensions but seldom their PCB footprint. Does it exist books or Website about this ? Thanks for help.

 

[buzzp]

There are industry standard footprints for things like transistors, some diodes (careful with these), etc. Usually the package is referenced: transistors may be TO-92, TO-220, etc Diodes maybe DO-41 or DO-35. The same will apply to SMT components. If they dont reference a 'package' then I would contact them for footprints. Generally, if a footprint is not given then it can be got from the pin dimensions, etc. There are web sites dedicated to the PCB designer that would likely have standard footprints. I am sorry I cant give you any web addresses. Our PCB designer handles these sorts of things. Good Luck.

 

[electricuwe]

If you buy a PCB design software it will include usually footprints of a lot of standard components. The only thing you have to do is to check if these footprints are suitable for the components you intend to use. For components not included in the libaries look at the manufacturers datasheet for creating your own footprints (If no datasheet is available you shouldn't use the component).

I can strongly recommend to do this work carefully, because failing to create proper footprints is responsible for more than half of the PCB design errors (my experience from supervising students creating PCB designs).

 

[SteveSmith]

electricuwe is correct in that you should always double check the library parts supplied with your software as they are rarely correct for your needs. If it's surface mount footprints you need here are a couple of sources:

http://www.ipc.org

- go to their IPC-SM-782 land pattern calculator

http://www.smtplus.com

- they sell books, calculators & libraries

http://www.pcbstandards.org/downloa...lators/Landpattern/Landpattern Calculator.xls

- a metric only thru hole & surface mount calculator

ALso you might want to get from the IPC their standards
IPC-2221 & IPC-2222 for general design standards.

Regards, Steve Smith
Product Engineer
Staco Energy Products Co.

http://www.stacoenergy.com