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本帖最后由 dbit 于 2011-10-7 16:40 编辑 " J. l* u, E) w2 R+ V
123456sz 发表于 2011-10-5 00:30 ![]()
+ o6 Z# H- f2 b7 N8 b7 z6 v2 V) F! j更改铜厚没有反应
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: X% r. }1 u+ r" y G8 r% t% X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。% R ^- v) x- h. \- y
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所有计算依据:IPC-2221标准制定;
- M( d, w* z: n! [: WIPC-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:: i- d- A! D0 Y3 F
Generic Standard on Printed Board Design4 [+ O& v) T- S- G- ?- B
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trace width calc
4 i ^+ Z8 X6 s0 z% }. p4 oArea[mils^2] = (Current[Amps]/(k*(Temp_Rise[deg. C])^b))^(1/c) ; m- [, n: y6 X: W9 G
Then, the Width is calculated:
: {+ F7 L2 p5 S# Y( @Width[mils] = Area[mils^2]/(Thickness[oz]*1.378[mils/oz]) ! C* [% O9 H. S/ E$ t7 ?* J7 c
For IPC-2221 internal layers: k = 0.024, b = 0.44, c = 0.725 * [" T9 L: G3 j% E, J
For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725 % H0 v; d. H, S5 E
where k, b, and c are constants resulting from curve fitting to the IPC-2221 curves
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$ `' N3 d8 E+ v$ w% L( lPCB VIA calculator
1 r3 N9 I/ `8 b4 K9 NResistance = Resistivity*Length/Area ' ]" c! {# g. Q
Area = pi*(Inner_dia + Plating_thk)*Plating_thk
& s2 b; V) x0 tResistivity = 1.9E-6 Ohm-cm (plated copper) * [! Q3 n6 X( W5 m6 Q
(plated copper is much more resistive than pure copper)
% D9 ~ u5 z1 |# yCopper Thermal_Resistivity = 0.249 cm-K/W (at 300K) . a$ `) ?+ U0 x
Est_Ampacity [Amps] = k*(Temp_Rise [deg C])^b*(Area [mils^2])^c
2 H! x. T' `5 n& p* \6 dFor IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725
% u' s5 z9 I* H& A5 k- h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
