Re: gEDA-user: size of 0402 footprint

[Steve Meier <smeier@xxxxxxxxxxxxxxxxxxx>]

The IPC SM-782A specification for the 0402

in mm

Package

Length min 1.00 
Length max 1.10 
pad separation min 0.40 
pad separation max 0.70 
Width min 0.48 
width max 0.60 
pad length min 0.10 
pad length max 0.30 
height max 0.40

Length = Pad Length + pad separation + Pad Length






Land Pattern 

length is along the x axis
width is along the y axis
both pads are on the x axis

Center of pad to center of pad = 1.30
pad length = 0.9
pad width = 0.7




Note: IPC land pattern specs tend to be pessimistic (larger) then most
component manufacturers recommend.

using the IPC suggestions you end up with a Land Pattern of 2.2mm by 0.7
mm for a device which is 1 mm by 0.5 mm





Steve Meier


On Mon, 2008-07-14 at 10:49 -0400, Dan McMahill wrote:
> Kai-Martin Knaak wrote:
> > On Mon, 14 Jul 2008 00:55:33 -0400, DJ Delorie wrote:
> > 
> >> What's the difference between the RES, CAP, and IND variants?
> > 
> > http://lilalaser.de/tmp/1005_footprints_in_geda_lib.png
> > 
> > The gap seems to be smallest for inductors and largest for resistors. Pad 
> > size is different too.
> 
> small differences in nominal dimensions of the packages.  One problem is 
> that evidentially there is no standard that fully defines what a '1005' 
> (aka 0402 in imperial units) package is.
> 
> You might get some amusement (or you may be disgusted) from this:
> 
> http://www.pcblibraries.com/Forum/forum_posts.asp?TID=1719
> 
> It mentions the lack of standards for SMT resistors but really shows the 
> problem with SOT-23's...
> 
> -Dan
> 
> 
> _______________________________________________
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> geda-user@xxxxxxxxxxxxxx
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