One item that's been pending for a good while are the footprints for
standard passive components, i.e., the ubiquitous 0402, 0603, etc.
There is a bewildering variety of pad sizes and keepout areas in
use in the industry. A few examples:
0402 (1005), package about 1 x 0.5 mm, terminals 0.2-0.25 mm:
Package Overall size Outline (keepout)
(pads)
My 0402 [1] - 1.30 x 0.60 1.55 x 0.85
GTA02 (silk) - - 2.0 x 1.1
GTA02 (real) - 1.4 x 0.5 1.7 x 0.8
AVX [2] 1.0 x 0.55 1.7 x 0.55 -
Panasonic [3] 1.0 x 0.5 1.5 x 0.5 * -
Vishay [4] 1.0 x 0.5 1.3 x 0.6 -
0603 (1608), package about 1.6 x 0.8 mm, terminals 0.3 mm:
Package Overall size Outline (keepout)
(pads)
My 0603 [2] - 2.0 x 0.9 2.25 x 1.15
KiCad SM0603 - 2.2 x 1.15 2.3 x 1.3
AVX [2] 1.6 x 0.81 2.3 x 0.8 -
Panasonic [3] 1.6 x 0.80 2.1 x 0.8 * -
Vishay [4] 1.55 x 0.85 2.0 x 0.9 -
[1] http://people.openmoko.org/werner/gta02-core/gta02-core-modules.pdf
[2] http://www.avx.com/docs/Catalogs/accuf-p.pdf
[3] http://industrial.panasonic.com/www-data/pdf/AOA0000/AOA0000CE1.pdf
[4] http://www.vishay.com/doc?20035
* Panasonic specify pad sizes +/- 0.1 mm. Size shown is average.
There are the following goals here:
1) make the keepout area large enough that we won't have problems
fitting the components
2) make the pads large enough that also soldering will go well
3) make the keepout area small enough that it won't routinely get
violated because "everyone knows there's a lot of slack."
If you look at the GTA02 silkscreen, that's precisely what
happened there. Good luck finding the ones that are really too
close :-)
I took my parameters from Vishay's reference and just added a 4 mil
clearance for the keepout area. For 0603, this is also within the
range of Vishay's parameters. For 0402, Vishay are 0.1 mm shorter
than anyone else.
Comments ?
- Werner
_______________________________________________
gta02-core mailing list
[email protected]
https://lists.openmoko.org/mailman/listinfo/gta02-core
