From 3a80f068ba047441b9521f0e4df6778ee48d7736 Mon Sep 17 00:00:00 2001 From: Werner Almesberger Date: Tue, 22 Mar 2011 12:26:46 -0300 Subject: [PATCH] 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 --- modules/INFO | 27 +++++++++++++++++++++++++-- modules/qfn.fpd | 4 ++-- 2 files changed, 27 insertions(+), 4 deletions(-) diff --git a/modules/INFO b/modules/INFO index 3691c8a..0c12868 100644 --- a/modules/INFO +++ b/modules/INFO @@ -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 diff --git a/modules/qfn.fpd b/modules/qfn.fpd index 259f5f6..a9b15cc 100644 --- a/modules/qfn.fpd +++ b/modules/qfn.fpd @@ -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