diff --git a/modules/INFO b/modules/INFO index 91eb934..3691c8a 100644 --- a/modules/INFO +++ b/modules/INFO @@ -66,6 +66,22 @@ F: mmcx-f-edge N: 73415-0961 # USB A plug for SMT +# +# Note: the signal pads are enlarged by 0.2 mm and their center is shifted by +# 0.1 mm with respect to the reference. +# +# According to the data sheet, the leads terminate at (2.00+/-0.10 mm)/2+ +# 2.48 mm = 3.48+/-0.10 mm from the center. The reference footprint puts the +# edge of the pads at (2.00+/-0.10 mm)/2+2.6 mm = 3.6 mm+/-0.10 mm, so the +# maximum lead end could be at 3.58 mm while the minimum pad edge could be at +# 3.5 mm. +# +# Assuming that the pad is intended to extend a bit beyond the lead, we need +# to add 0.2 mm to compensate for these tolerances. (The pad tolerance may not +# be intended to be used this way, however, we still have to consider small +# errors in registration, which also amount to about 0.1 mm, so the calculation +# remains valid.) +# F: usb_a_plug_smt # SOT-323 package with counter-clockweise or clockwise pin assignment diff --git a/modules/usb_a_plug_smt.fpd b/modules/usb_a_plug_smt.fpd index 63fd404..5be3095 100644 --- a/modules/usb_a_plug_smt.fpd +++ b/modules/usb_a_plug_smt.fpd @@ -3,7 +3,7 @@ frame pad { table { h, w } - { 2mm, 1.2mm } + { 2mm+2*enlarge, 1.2mm } __0: vec @(w/2, h/2) __1: vec @(-w/2, -h/2) @@ -18,7 +18,9 @@ frame pads { { 3, -1mm } { 4, -3.5mm } - __0: vec @(0mm, 2.6mm) + set enlarge = 0.1mm + + __0: vec @(0mm, 2.6mm+enlarge) __1: vec .(x, 0mm) frame pad . }