SMD pad size based on soldering method...

[alank2]

Hi Everyone,

Most of my experience in through hole, but I've done some SMD soldering (by hand) and am looking to do more SMD via reflow oven.

What I have been doing was sizing pads based on this criteria:

2mils on all sides except the side approached from the soldering iron which is 20mils

It has worked fine for hand solder the few SMD projects I've done, but for reflow what is ideal?  What do you use?

Thanks,

Alan

[8086]

I use IPC standard footprints or whatever the datasheet specifies.

[Richard Head]

Me too. Also IPC standard or datasheet footprint. Never had a problem yet.

[alank2]

Thanks guys, it looks like the IPC document is not freely available, but there is some sort of tool that has the footprints that is.  Is this true?

Thanks,

Alan

[zapta]

I use IPC standard footprints or whatever the datasheet specifies.

Same here, with one exception. I was using a small resonator where the recommended pad was too small to hand solder and when I enlarged the pad the stencil allowed too much solder paste, almost shortening to the case. I ended up using the larger pad but with smaller smd cutout so I can can hand solder and use stencils.

[Niklas]

Thanks guys, it looks like the IPC document is not freely available, but there is some sort of tool that has the footprints that is.  Is this true

Have a look at this free IPC viewer:
http://www.pads.com/downloads/lp-viewer-download/

[calexanian]

Consider a hot air station. I find a hot plate and a hot air station to be better and nearly as fast, if not faster than a home made reflow oven. Also IPC standard footprints here as well. Just the standard one in eagle works for me.

[mrflibble]

Consider a hot air station. I find a hot plate and a hot air station to be better and nearly as fast, if not faster than a home made reflow oven.

Another vote for the hot plate + hot air method. Preheating the pcb makes it totally easy.

[alank2]

I checked out the viewer, but how do you know which one to use?  There are three libraries, least, nominal, and most.  Then looking for a 20 pin soic 0.3" width I find 10 different land patterns!  4 of the 10 are one JEDEC standard, 2 are another, and then 4 don't have a standard.