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本帖最后由 dbit 于 2011-10-7 16:40 编辑 % j V; N5 ~2 G( E8 A0 l
123456sz 发表于 2011-10-5 00:30 ![]() 7 M. e" r) |* F) c5 w R' w
更改铜厚没有反应
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' j$ F; _4 n7 ?% Y# P: a6 W4 C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。' m" S0 M; M1 e! `, @! }. k/ ?
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所有计算依据:IPC-2221标准制定;
0 F0 ~ c+ E; B" ]. G" C) N& DIPC-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:
0 j0 s7 O& }$ w# e' o* Q/ PGeneric Standard on Printed Board Design
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trace width calc; n d* T% {3 \. C
Area[mils^2] = (Current[Amps]/(k*(Temp_Rise[deg. C])^b))^(1/c) , ?: j3 |+ }& S. s) \ K
Then, the Width is calculated:
8 H3 M2 M/ r6 S6 pWidth[mils] = Area[mils^2]/(Thickness[oz]*1.378[mils/oz])
" |, r" D0 _- Q, vFor IPC-2221 internal layers: k = 0.024, b = 0.44, c = 0.725
8 C/ e( T# z2 E) z3 G6 {For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725
0 s0 { O; x7 h1 E! h6 swhere k, b, and c are constants resulting from curve fitting to the IPC-2221 curves 3 N* V! D+ l5 }& e' N# |
0 |2 Z" E1 d) [" r7 R' gPCB VIA calculator
6 v- W/ w0 U( i/ K& IResistance = Resistivity*Length/Area
$ K+ i9 l. h- i6 lArea = pi*(Inner_dia + Plating_thk)*Plating_thk
7 w2 O# t: @7 R7 G5 u& A/ N9 ]Resistivity = 1.9E-6 Ohm-cm (plated copper) , p) o; K+ b6 g. b
(plated copper is much more resistive than pure copper)
, f' i! D0 Q! e( d/ B DCopper Thermal_Resistivity = 0.249 cm-K/W (at 300K)
" V( d& W+ G! s5 ?9 U! R$ dEst_Ampacity [Amps] = k*(Temp_Rise [deg C])^b*(Area [mils^2])^c : z# F: m: n0 x, h/ k9 j* ?& x. T c
For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725 1 D F8 m/ v( c% X: D
我做的一个xls方式的计算式，可以算电流的。! D) E5 }1 n7 F
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楼主
发表于 2011-10-7 23:04
