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本帖最后由 dbit 于 2011-10-7 16:40 编辑
! y3 k4 q. D8 r7 T+ T123456sz 发表于 2011-10-5 00:30 ![]()
) l6 k$ J# n. B, D& z3 O更改铜厚没有反应
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6 P. u6 b) _4 \! [! C2 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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) i: P9 x4 m$ |. K- |( R+ c& B所有计算依据:IPC-2221标准制定;" R7 s+ V# \5 ^1 g8 j2 [" a. D+ n- 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:, T/ o2 ^& ?/ \8 s0 W
Generic Standard on Printed Board Design
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- s2 j, r* Y4 R+ Etrace width calc$ x) [$ K% @. {$ X. _
Area[mils^2] = (Current[Amps]/(k*(Temp_Rise[deg. C])^b))^(1/c) 7 h, Y/ S& T. P R+ O
Then, the Width is calculated:
" A5 e( ?, u2 Q8 @" i. UWidth[mils] = Area[mils^2]/(Thickness[oz]*1.378[mils/oz]) , i& U( v8 a! j3 X4 ]
For IPC-2221 internal layers: k = 0.024, b = 0.44, c = 0.725
: t- E7 ^6 U% ^" vFor IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725 1 w2 @( w2 M9 R( n; M6 C
where k, b, and c are constants resulting from curve fitting to the IPC-2221 curves
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PCB VIA calculator " [4 l6 ~! E& Q
Resistance = Resistivity*Length/Area 1 }2 @0 y% g& X4 y& L
Area = pi*(Inner_dia + Plating_thk)*Plating_thk " Z4 y) h* W, }6 G6 q2 U Y' Z$ [. u' R6 d
Resistivity = 1.9E-6 Ohm-cm (plated copper) 1 f- g, h2 I7 P
(plated copper is much more resistive than pure copper) # p- Q% o6 e) A) f3 r1 T
Copper Thermal_Resistivity = 0.249 cm-K/W (at 300K) / c( V& H* i5 y1 X3 m
Est_Ampacity [Amps] = k*(Temp_Rise [deg C])^b*(Area [mils^2])^c $ _# Q; u6 |' d! C2 y( B4 }
For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725
% V' s: V g) X2 B+ x我做的一个xls方式的计算式，可以算电流的。5 g6 x' h- z" n, u7 V
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发表于 2011-7-25 09:32
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