Dear Frnds,
Is there any IPC Standard document available for footprints specially for smd packages like PQFP, LQFP, DFN etc.How much should be length more than actual pad e.g. 5 mils, 10 mils or 20 mils etc.
Also for 0402 & 0603 components how much should be pad length & width more than the actual component size 0402 -- 1mm x 0.5 mm so what should be pitch & pad size ?
Thanks in advance,
Byee...
The document is "IPC-7351A Generic Requirements for Surface Mount Design and Land Pattern Standard". You have to buy it from www.ipc.org.
The size of the pad depends on where you are using the footprint. IPC-7351A gives the specs for three different footprint sizes - Least, Norminal, and Most. Those footprint sizes are based on the density of the board on which you are using the footprint. "Most" size is used on low density boards, "Nominal on moderate density boards, and "Least" on high density boards.
If you want to look at the recommended footprints, without buying the standard, you can download a free viewer at: **broken link removed**
There's more info available at: **broken link removed**
This is the same viewer available from the IPC footprints site. I just didn't want to give the PCBlibraries bunch a free commercial. They're a manipulative, money grubbing pack of thieves.
That's an outdated copy of the standard. The effective standard is now IPC-7351A, and the method of calculating the footprint pad size has changed completely in the new standard.