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increased solder paste deposits in QFN32-VHHD-2 and QFN32-VHHD-6

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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
This commit is contained in:
Werner Almesberger 2011-03-22 12:26:46 -03:00
parent 7cf2b0d352
commit 3a80f068ba
2 changed files with 27 additions and 4 deletions
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27
modules/INFO
View File

@ -24,10 +24,33 @@ F: qfn
# http://www.nxp.com/package/SOT617-1.html
# http://www.nxp.com/package/SOT617-3.html
#
# Solder paste:
#
# Footprint Center pad Closest NXP (with complete land pattern)
# QFN28-Atmel 2.4 mm for further study
# QFN28-SiLabs 3.3 mm use SiLab's specification
# QFN32-VHHD-2 3.7 mm between SOT818-1 and SOT788-1
# QFN32-VHHD-6 3.4 mm SOT818-1
#
# From NXP:
#
# Package Pad Paste zone Islands Isl. size Isl. gap
# SiLabs 3.25 3.1 3 x 3 0.9
# SOT818-1 3.4 1.75 2 x 2 0.75 0.25
# SOT788-1 4.0 2.4 3 x 3 0.6 0.3
#
# NXP rules (AN10365):
# - paste zone = 35% of pad area
# - paste coverge = 20% of pad area
#
# Our parameters:
#
# Package Pad Paste zone Islands Isl. size Isl. gap Zone Coverage
# QFN32-VHHD-2 3.7 2.15 3 x 3 0.5 0.25 34% 20%
# QFN32-VHHD-6 3.4 1.95 2 x 2 0.75 0.45 33% 19%
#
# Known bugs:
#
# - we should distribute the solder paste in an array of small
# squares instead of just covering the whole center pad.
# - really ought to merge all the various QFN definitions (we have more
# over at gta02-core) into a single QFN file with a big mean table of
# everything

4
modules/qfn.fpd
View File

@ -105,8 +105,8 @@ table
{ pins, variant, X1, Y1, X2, Y2, E, C1, C2, SE, SNX, SNY, SX, SY }
{ 28, "Atmel", 0.24mm, 0.7mm, 2.4mm, 2.4mm, 0.45mm, 4.1mm, 4.1mm, 1mm, 2, 2, 0.8mm, 0.8mm }
{ 28, "SiLabs", 0.25mm, 0.9mm, 3.3mm, 3.3mm, 0.5mm, 4.8mm, 4.8mm, 1.1mm, 3, 3, 0.9mm, 0.9mm }
{ 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 }
{ 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 }
{ 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 }
{ 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 }
set w = 5mil