SMD Package Sizes

Evening all,

I've looked through the forum and can't find a solution for this, so here goes:

I'm looking to use the 40X2 and 20X2 in a project with limited space, so I've gone for the surface mount option. However, the PICAXE website only tells you that the SMD chips are 300mil / 7.62mm SOIC / 44 pin 2mm TPFQs. Can anyone expand on those measurements, eg. pitch and dimensions?

Cheers
 
That's perfect - I didn't see that :)

Can I just confirm though, the Microchip datasheets list the SOIC packages as being 7.5mm wide, the PICAXE website as 7.62 - I presume they are one and the same?
 

srnet

Senior Member
Why is the width of the plastic package itself important ?

The size of the SMT footprint, the pads the leads go on, is the important factor.

The PIC processor data sheets are the reference to use for sizing.
 
The only reason is that the footprints pre-loaded into KiCAD reference the width and pin pitch, no other dimensions :) I simply want to avoid having to create custom footprints
 

rq3

Senior Member
That's perfect - I didn't see that :)

Can I just confirm though, the Microchip datasheets list the SOIC packages as being 7.5mm wide, the PICAXE website as 7.62 - I presume they are one and the same?
No, that is an error on the Picaxe site. The plastic body of a 20 pin SOIC surface mount Picaxe is 7.5mm wide, which doesn't matter at all. It's the surface mount copper pattern on the top surface of the board that counts.

The 7.62mm actually refers to the 0.300 inch through hole row spacing for a standard DIP20 through hole package, and is not correct when referring to a surface mount SOIC package.
 

srnet

Senior Member
The only reason is that the footprints pre-loaded into KiCAD reference the width and pin pitch, no other dimensions :) I simply want to avoid having to create custom footprints
There are dimensions in KiCAD, just use the grid and cursor to measure them.
 
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