Craig Niederberger wrote: > What I'm struggling with is a footprint for a LM2575 with a TO-220-5 > footprint, which has 5 pins, each pin with max dimensions 0.038 in x > 0.025 in
By coincidence I did a similar 5-pin TO220 footprint for my first geda project a few months ago. It was called PENTAWATT and had the even pins shifted. So there was more space between the pins. > Element[0x00 "TO-220 5 pin" "" "" 10000 10000 0 4800 0 100 ""] > ( > Pin[ 0 0 6000 1400 6700 4600 "Pin_1" "1" 0x00000101] This is 7 mil annular ring, 7 mil clearance to the next net and 3.5mil clearance of the mask. However, the fabs that do my boards (Basista, Beta-Layout) insist on 8 mil minimum annular ring for their regular service. Clearance may be as low as 6 mil, though. Hole thickness 46 mil is a good value for TO220 type footprints. The pentawatt footprint on my little practice board was drilled according to the same numbers and the component fits just fine. > Element[0x00 "2mm header" "" "" 10000 10000 0 4800 0 100 ""] > ( > Pin[ 0 0 5450 4900 7900 3000 "Pin_1" "1" 0x00000101] This is 19.5 mil clearance to the next net, 12 mil annular ring and 12 mil mask clearance. 20 mil clearance is a lot. Are there large voltages between the pins? I'd reduce mask clearance to 4 mil or less. After all, only the pad is supposed to be exposed. ---<(kaimartin)>--- PS: This is my pentawatt footprint. I did it with the pcb GUI according to a metric data sheet. Hence the random looking numbers for pin positions. Element[0x0 "PENTAWATTV" "" "" 12590 46145 0 0 0 100 0x0] ( Pin[0 0 6600 2000 8600 4600 "" "1" 0x00000101] Pin[6693 -15748 6600 2000 8600 4600 "" "2" 0x00000001] Pin[13386 0 6600 2000 8600 4600 "" "3" 0x00000001] Pin[20079 -15748 6600 2000 8600 4600 "" "4" 0x0000001] Pin[26772 0 6600 2000 8600 4600 "" "5" 0x00000001] ElementLine [-7087 -14173 -7087 -33071 1000] ElementLine [-7087 -27559 33858 -27559 1000] ElementLine [28347 -14173 28347 -3937 1000] ElementLine [33858 -33071 33858 -14173 1000] ElementLine [-7087 -33071 33858 -33071 1000] ElementLine [1575 -14174 1575 -3938 1000] ElementLine [-1575 -14173 -1575 -3937 1000] ElementLine [25197 -14173 25197 -3937 1000] ElementLine [11811 -14173 11811 -3937 1000] ElementLine [14961 -14173 14961 -3937 1000] ElementLine [33858 -14173 23622 -14173 1000] ElementLine [10236 -14173 16536 -14173 1000] ElementLine [-7087 -14173 3150 -14173 1000] ) -- Kai-Martin Knaak [EMAIL PROTECTED] http://lilalaser.de/blog _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user