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本帖最后由 dbit 于 2011-10-7 16:40 编辑 3 J2 \( E6 j, h3 L* a0 P
123456sz 发表于 2011-10-5 00:30 ![]()
8 I9 g8 Z6 E. o" @$ f+ z更改铜厚没有反应
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谢谢你帮忙查出问题，另外过孔不需要铜厚，我已去掉，线宽的公式中，没有除铜厚，现修正。* K" L3 w P" `1 B" d2 k# E
2 K* l% {5 @$ }* w$ m: J( L所有计算依据:IPC-2221标准制定;, ^; r! Q. R0 z+ d- n
IPC-2221标准描述:是由IPC组织制定的关于PCB设计的通用标准,英文名为:$ j* J! S S4 h; Y: ?& _7 T
Generic Standard on Printed Board Design( ]: P- v& a4 Q
4 }, R, Q9 M8 Z( d/ j1 O" S0 Etrace width calc* ]/ } y7 f* k* w% v- w# R) Q
Area[mils^2] = (Current[Amps]/(k*(Temp_Rise[deg. C])^b))^(1/c) , L! B$ y& ?; P/ M W
Then, the Width is calculated: 2 U* u( l0 s$ P0 r$ z! p, b
Width[mils] = Area[mils^2]/(Thickness[oz]*1.378[mils/oz])
" j& {& J1 \1 B. YFor IPC-2221 internal layers: k = 0.024, b = 0.44, c = 0.725 8 m5 |9 G! R' ~
For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725
z* {7 O% K6 N) Bwhere k, b, and c are constants resulting from curve fitting to the IPC-2221 curves 8 S/ t) r) A7 ~ E2 M9 g) l# J
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PCB VIA calculator
6 f. ~# ^$ t1 x9 z0 H MResistance = Resistivity*Length/Area
. \0 q% t" V2 l+ @+ XArea = pi*(Inner_dia + Plating_thk)*Plating_thk 9 l) Y; O4 F; e' |
Resistivity = 1.9E-6 Ohm-cm (plated copper) / {3 f2 H9 F$ ]/ j; ~' \
(plated copper is much more resistive than pure copper)
, J& s L" [# u5 s+ aCopper Thermal_Resistivity = 0.249 cm-K/W (at 300K) / Q1 O) c1 q) I4 J& D" I; j
Est_Ampacity [Amps] = k*(Temp_Rise [deg C])^b*(Area [mils^2])^c " _. B. h( L) l& U- D
For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725 % l9 Z2 z. _' m" M8 Q
我做的一个xls方式的计算式，可以算电流的。
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发表于 2011-7-25 09:32
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