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本帖最后由 dbit 于 2011-10-7 16:40 编辑 " }& e% m$ w v9 U2 J' m* h
123456sz 发表于 2011-10-5 00:30 ![]() : i! h, Z, L% Y5 M1 ?
更改铜厚没有反应
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' m- I j) P6 W/ c2 Z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。. U: ~0 {+ R% M t: L/ `4 [$ O
( e. L% q& K3 n2 @所有计算依据:IPC-2221标准制定;2 H! l/ _5 w! L3 u
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:( G3 | n2 q: s# A9 A1 b2 y
Generic Standard on Printed Board Design
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trace width calc8 S4 C; d2 q0 C. e" K; @! |9 F) Y/ \
Area[mils^2] = (Current[Amps]/(k*(Temp_Rise[deg. C])^b))^(1/c)
, J& G2 q: \; _- N! R" p$ T$ [6 }Then, the Width is calculated: 4 b9 h2 _* a1 ?
Width[mils] = Area[mils^2]/(Thickness[oz]*1.378[mils/oz])
/ U$ \) B5 H+ D) ^For IPC-2221 internal layers: k = 0.024, b = 0.44, c = 0.725 , q1 B: F% S- _/ X5 z6 l
For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725 7 G: `3 Q ~0 N5 n2 ]8 m
where k, b, and c are constants resulting from curve fitting to the IPC-2221 curves 2 T+ C5 [4 R* l0 V
, g3 j5 I; k9 x( D9 V3 o) K2 _PCB VIA calculator ( \$ v. }% Q8 p& b
Resistance = Resistivity*Length/Area
) i$ O u3 T$ q- F9 QArea = pi*(Inner_dia + Plating_thk)*Plating_thk 2 T( @# ~0 y8 i
Resistivity = 1.9E-6 Ohm-cm (plated copper) 7 ?6 F, O+ m6 b. v, l7 h
(plated copper is much more resistive than pure copper) 3 r) _3 |$ u$ F- n+ y) ~
Copper Thermal_Resistivity = 0.249 cm-K/W (at 300K) 5 V8 |1 }+ d- J4 O; a% m
Est_Ampacity [Amps] = k*(Temp_Rise [deg C])^b*(Area [mils^2])^c
V1 A: B# _% f, s* q0 VFor IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725
% Q* j- a$ D9 K+ }5 a我做的一个xls方式的计算式，可以算电流的。
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楼主
发表于 2011-10-7 23:04
