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本帖最后由 dbit 于 2011-7-16 19:32 编辑
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) H+ {+ L) `% s% c1 r所有计算依据:IPC-2221标准制定;) M# N8 ^, j" }1 N4 e+ @8 M
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:
/ C4 V. \4 Z1 |- qGeneric Standard on Printed Board Design1 Z8 v& Y+ x( Z1 b+ q# m
[/ C0 z1 @8 {& \7 W0 Y1 Jtrace width calc+ M( c+ w6 f7 f, U- }- X
Area[mils^2] = (Current[Amps]/(k*(Temp_Rise[deg. C])^b))^(1/c) 8 X6 B7 Z) S5 }' V7 ?
Then, the Width is calculated: - V# q! r. s! L
Width[mils] = Area[mils^2]/(Thickness[oz]*1.378[mils/oz]) 8 Y v- d( Y m! _/ m, A) p Q! d
For IPC-2221 internal layers: k = 0.024, b = 0.44, c = 0.725 6 a' @% V8 [4 E! P W5 t
For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725
& h, H: y' q8 nwhere k, b, and c are constants resulting from curve fitting to the IPC-2221 curves
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PCB VIA calculator 5 ?& b" J+ u$ ]9 E
Resistance = Resistivity*Length/Area 2 |$ z6 Q) q/ F
Area = pi*(Inner_dia + Plating_thk)*Plating_thk
W: r3 d1 S q5 y7 u7 `1 QResistivity = 1.9E-6 Ohm-cm (plated copper) ! k/ k% E" w& X# g* _8 n$ J
(plated copper is much more resistive than pure copper)
. }$ d, B; p0 [* r5 ICopper Thermal_Resistivity = 0.249 cm-K/W (at 300K) 5 n& g$ g, i2 h7 W
Est_Ampacity [Amps] = k*(Temp_Rise [deg C])^b*(Area [mils^2])^c ; w- l; L0 a, B% f
For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725 ' V7 S* Z) T% ]1 U
我做的一个xls方式的计算式,可以算电流的。" I6 ] Q& h( e4 ?
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):% P7 X& L; A+ x. }6 x8 P
公式有修正,详见31#1 E4 R) J' l5 `# B9 W( a( X1 s& z
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补充内容 (2011-10-7 16:44):5 c; d8 G" C4 H. d5 [6 _. Y3 R
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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