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本帖最后由 dbit 于 2011-7-16 19:32 编辑 2 o% ~3 f1 l6 P n C
5 J, z& w" t1 V( a ^! E1 G+ q; j! M所有计算依据:IPC-2221标准制定;7 D/ I6 c9 u( `+ n
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:
9 d3 z7 Q" L: u7 DGeneric Standard on Printed Board Design
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% v* L1 y9 F4 ^# \+ s1 ]trace width calc
. t3 A: g$ _) s( c3 D/ CArea[mils^2] = (Current[Amps]/(k*(Temp_Rise[deg. C])^b))^(1/c)
/ y1 U5 i+ {3 ~& `* {+ `0 j# ZThen, the Width is calculated: " ~2 a1 F* S% m R2 Z5 n
Width[mils] = Area[mils^2]/(Thickness[oz]*1.378[mils/oz])
N0 Z6 `: h$ ^! A# ]For IPC-2221 internal layers: k = 0.024, b = 0.44, c = 0.725 * j4 ]9 ?/ r( g) I% B3 {9 U
For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725
) g# Y+ g$ r- l3 J' Lwhere k, b, and c are constants resulting from curve fitting to the IPC-2221 curves + c. S, _2 B2 }' w. l1 N( B) Y
3 ]# h( b( w! [! U2 }! g: D* jPCB VIA calculator
0 K. x; q/ \4 x2 kResistance = Resistivity*Length/Area 6 w' A3 ~0 b! g! U& R9 j
Area = pi*(Inner_dia + Plating_thk)*Plating_thk 6 E$ C1 T+ J- k+ W+ G; a
Resistivity = 1.9E-6 Ohm-cm (plated copper)
, m4 R( T5 r! Z# Q(plated copper is much more resistive than pure copper)
1 }# W1 c7 m3 R- XCopper Thermal_Resistivity = 0.249 cm-K/W (at 300K)
( l, o5 |1 @2 j, z" M" V! dEst_Ampacity [Amps] = k*(Temp_Rise [deg C])^b*(Area [mils^2])^c 1 v3 q: u% U' C9 l. K* i5 U5 O
For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725 : ~2 J/ R, s* {7 ^) u4 u: g# W" j U+ Q
我做的一个xls方式的计算式,可以算电流的。
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VIA trace IPC-2221.zip
(2.94 KB, 下载次数: 511)
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补充内容 (2011-10-7 16:39):
, [2 _' K2 n0 ?8 J公式有修正,详见31#
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补充内容 (2011-10-7 16:44):3 u) k# X! C8 @
本人目前等级有限,不能直接修改这个附件,请大家到31#去下载,谢谢。另外如果管理员有看到的话,可否帮忙去掉这个附件,把31#的附件放在这,并加注说明。 |
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