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本帖最后由 dbit 于 2011-10-7 16:40 编辑
1 [/ }, u. I( ^+ m8 O123456sz 发表于 2011-10-5 00:30 ![]() . L2 c1 t' \7 ~: D f, k" H$ [
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。: {8 a9 |- I4 ^% ~9 A! a' ?( }/ u
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所有计算依据:IPC-2221标准制定;5 ~! p% c1 M" y
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:9 v! b8 f7 g; U8 l' M9 a
Generic Standard on Printed Board Design4 Q$ X. j a( X2 _# N
4 a* j B7 o" L. |- xtrace width calc
, [' M: g! G2 _( H% H5 ~; H2 ]Area[mils^2] = (Current[Amps]/(k*(Temp_Rise[deg. C])^b))^(1/c)
. _# D, y0 W& H, j/ l1 }. ]Then, the Width is calculated: * h7 p& m* m, I- f& t+ T6 O! r* a" }
Width[mils] = Area[mils^2]/(Thickness[oz]*1.378[mils/oz]) " i) s* n6 p# I4 E& y# n8 j& ?$ T- I
For IPC-2221 internal layers: k = 0.024, b = 0.44, c = 0.725
8 c# T9 T7 p. n3 [+ ]8 QFor IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725 7 a) k N3 R6 d+ ?. C6 E; n2 O
where k, b, and c are constants resulting from curve fitting to the IPC-2221 curves
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PCB VIA calculator
4 R) e5 ?' C" E/ k* @Resistance = Resistivity*Length/Area
- n- Q' s- [3 W% n4 NArea = pi*(Inner_dia + Plating_thk)*Plating_thk + e2 p+ A8 u7 N1 Z% ~( j
Resistivity = 1.9E-6 Ohm-cm (plated copper)
5 m7 A |- ^# t(plated copper is much more resistive than pure copper) 9 V) r1 w) s, q6 I" f
Copper Thermal_Resistivity = 0.249 cm-K/W (at 300K) 2 z6 q" A/ q6 T8 C* x( n7 O& O0 D
Est_Ampacity [Amps] = k*(Temp_Rise [deg C])^b*(Area [mils^2])^c 1 ] a5 A5 E! F4 {/ X+ F+ b9 g5 ~
For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725
! K/ T! p, J6 A% a+ w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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