Date:2011-03-22 16:26:46 (8 years 2 months ago)
Author:Werner Almesberger
Commit:3a80f068ba047441b9521f0e4df6778ee48d7736
Message:increased solder paste deposits in QFN32-VHHD-2 and QFN32-VHHD-6

Note that QFN28-Atmel and QFN28-SiLabs still need verifying.
QFN28-SiLabs is quite differnt from NXP's specification.

- modules/INFO: added description of solder paste deposit dimensioning
rules (based on NXP's AN10365)
- modules/qfn.fpd (QFN32-VHHD-2, QFN32-VHHD-6): increased solder paste
deposits according to the rules
Files: modules/INFO (1 diff)
modules/qfn.fpd (1 diff)

Change Details

modules/INFO
2424# http://www.nxp.com/package/SOT617-1.html
2525# http://www.nxp.com/package/SOT617-3.html
2626#
27# Solder paste:
28#
29# Footprint Center pad Closest NXP (with complete land pattern)
30# QFN28-Atmel 2.4 mm for further study
31# QFN28-SiLabs 3.3 mm use SiLab's specification
32# QFN32-VHHD-2 3.7 mm between SOT818-1 and SOT788-1
33# QFN32-VHHD-6 3.4 mm SOT818-1
34#
35# From NXP:
36#
37# Package Pad Paste zone Islands Isl. size Isl. gap
38# SiLabs 3.25 3.1 3 x 3 0.9
39# SOT818-1 3.4 1.75 2 x 2 0.75 0.25
40# SOT788-1 4.0 2.4 3 x 3 0.6 0.3
41#
42# NXP rules (AN10365):
43# - paste zone = 35% of pad area
44# - paste coverge = 20% of pad area
45#
46# Our parameters:
47#
48# Package Pad Paste zone Islands Isl. size Isl. gap Zone Coverage
49# QFN32-VHHD-2 3.7 2.15 3 x 3 0.5 0.25 34% 20%
50# QFN32-VHHD-6 3.4 1.95 2 x 2 0.75 0.45 33% 19%
51#
2752# Known bugs:
2853#
29# - we should distribute the solder paste in an array of small
30# squares instead of just covering the whole center pad.
3154# - really ought to merge all the various QFN definitions (we have more
3255# over at gta02-core) into a single QFN file with a big mean table of
3356# everything
modules/qfn.fpd
105105    { pins, variant, X1, Y1, X2, Y2, E, C1, C2, SE, SNX, SNY, SX, SY }
106106    { 28, "Atmel", 0.24mm, 0.7mm, 2.4mm, 2.4mm, 0.45mm, 4.1mm, 4.1mm, 1mm, 2, 2, 0.8mm, 0.8mm }
107107    { 28, "SiLabs", 0.25mm, 0.9mm, 3.3mm, 3.3mm, 0.5mm, 4.8mm, 4.8mm, 1.1mm, 3, 3, 0.9mm, 0.9mm }
108    { 32, "VHHD-2", 0.26mm, 0.69mm, 3.7mm, 3.7mm, 0.5mm, 5.1mm, 5.1mm, 0.8mm, 3, 3, 0.5mm, 0.5mm }
109    { 32, "VHHD-6", 0.26mm, 0.69mm, 3.4mm, 3.4mm, 0.5mm, 5.1mm, 5.1mm, 1.2mm, 2, 2, 0.7mm, 0.7mm }
108    { 32, "VHHD-2", 0.26mm, 0.69mm, 3.7mm, 3.7mm, 0.5mm, 5.1mm, 5.1mm, 0.8mm, 3, 3, 0.55mm, 0.55mm }
109    { 32, "VHHD-6", 0.26mm, 0.69mm, 3.4mm, 3.4mm, 0.5mm, 5.1mm, 5.1mm, 1.2mm, 2, 2, 0.75mm, 0.75mm }
110110
111111set w = 5mil
112112

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