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本帖最后由 dbit 于 2011-10-7 16:40 编辑 % N/ L/ L# X0 {, W; I1 ^
123456sz 发表于 2011-10-5 00:30 2 O9 t6 g" P! F/ Z7 y9 y t. d
更改铜厚没有反应
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]: r7 ?1 m9 ]) D, ?3 Z) j% S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。
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" ?9 q2 @8 v1 h" y6 G/ A% i; u所有计算依据:IPC-2221标准制定;
( o4 A# C' E! G' ?7 ]3 QIPC-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 |( w& }: f; H" o4 q4 D
Generic Standard on Printed Board Design
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trace width calc% d* g b+ Y5 | w* i2 X- r
Area[mils^2] = (Current[Amps]/(k*(Temp_Rise[deg. C])^b))^(1/c) $ v1 {0 P" O& O) f$ B
Then, the Width is calculated:
$ G& Y: [* j0 o+ ^# I" wWidth[mils] = Area[mils^2]/(Thickness[oz]*1.378[mils/oz]) + I8 y; u, b! O8 ^
For IPC-2221 internal layers: k = 0.024, b = 0.44, c = 0.725
& V$ D) a: S! s4 U) g( P3 eFor IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725
. C$ g; k3 t* a$ x, xwhere k, b, and c are constants resulting from curve fitting to the IPC-2221 curves
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PCB VIA calculator " p5 h; K8 o; o* E5 b# p
Resistance = Resistivity*Length/Area 2 l( ?3 M/ B' ~5 u' v; U
Area = pi*(Inner_dia + Plating_thk)*Plating_thk
& D# B: y/ E( M" M# `, _' s; e6 b$ BResistivity = 1.9E-6 Ohm-cm (plated copper)
, e0 N; e" b" X: e/ i r( u5 d& E(plated copper is much more resistive than pure copper)
7 a8 t* s2 _; G9 ECopper Thermal_Resistivity = 0.249 cm-K/W (at 300K)
) l2 r8 ?% I7 z# b4 ]Est_Ampacity [Amps] = k*(Temp_Rise [deg C])^b*(Area [mils^2])^c d I- `; C' v! q( F: g e4 M
For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725
& ^ n0 h6 r i- b3 `8 w我做的一个xls方式的计算式,可以算电流的。
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