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本帖最后由 dbit 于 2011-10-7 16:40 编辑
* k* z& S, F% K' Z123456sz 发表于 2011-10-5 00:30 ![]() q. O0 l' x* m: t* A
更改铜厚没有反应
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( O/ ~ w: @( Q- I, b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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所有计算依据:IPC-2221标准制定;
: v6 [2 I: o/ {' c) JIPC-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:
2 c6 B/ i9 W/ o& YGeneric Standard on Printed Board Design
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trace width calc! m/ g9 ?8 Y# R0 I
Area[mils^2] = (Current[Amps]/(k*(Temp_Rise[deg. C])^b))^(1/c)
% h& V1 z! w/ D( n, }% \9 HThen, the Width is calculated: & ?, a: i: C" ~
Width[mils] = Area[mils^2]/(Thickness[oz]*1.378[mils/oz]) 0 O, w- K8 ?' N, }- u7 ]
For IPC-2221 internal layers: k = 0.024, b = 0.44, c = 0.725
, R6 V4 a' h3 P1 b- PFor IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725 : H4 v1 m: S6 H2 T/ Z* D
where k, b, and c are constants resulting from curve fitting to the IPC-2221 curves
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3 R) ~3 y h* y: f* X" _PCB VIA calculator
' D4 N8 ?$ a$ m, P( J6 O! f0 {Resistance = Resistivity*Length/Area , R# d* V- x' b. `" ]( Z, J$ `
Area = pi*(Inner_dia + Plating_thk)*Plating_thk ) n4 F" q$ X% ?* Q
Resistivity = 1.9E-6 Ohm-cm (plated copper)
9 ?/ n" u. R9 O' m% Z(plated copper is much more resistive than pure copper)
7 A/ v9 H/ C. {" J* U7 CCopper Thermal_Resistivity = 0.249 cm-K/W (at 300K)
9 s4 V/ U2 b/ p9 Y" m+ ^7 yEst_Ampacity [Amps] = k*(Temp_Rise [deg C])^b*(Area [mils^2])^c
8 h% Y: @/ I5 Q9 g' }/ F) SFor IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725
/ J C3 _: i& v8 n/ G我做的一个xls方式的计算式，可以算电流的。, Q0 H" }2 D; k6 r0 C" y' |$ M" Q
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楼主
发表于 2011-10-7 23:04
