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本帖最后由 dbit 于 2011-10-7 16:40 编辑
; b2 C9 S7 T( u123456sz 发表于 2011-10-5 00:30 2 N, p0 s6 `! L. z* N4 S8 h
更改铜厚没有反应
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; A t6 g7 |! O6 X4 x/ \6 V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。/ y- g& `$ ]9 w2 Y3 M
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所有计算依据:IPC-2221标准制定;
_7 `% G2 J: M% r8 rIPC-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:
5 _: u" N5 J% b$ NGeneric Standard on Printed Board Design
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4 i f; _0 b! {) y" k$ qtrace width calc
. b0 b& j9 }8 j' r2 g0 |- oArea[mils^2] = (Current[Amps]/(k*(Temp_Rise[deg. C])^b))^(1/c) 8 D9 {! v9 ?5 d) R% z
Then, the Width is calculated: ' E& ]* b9 f, P
Width[mils] = Area[mils^2]/(Thickness[oz]*1.378[mils/oz])
3 _3 n7 W# o* {For IPC-2221 internal layers: k = 0.024, b = 0.44, c = 0.725 , J0 l( i# Y$ |+ G. J4 m) Q
For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725
4 P# K$ y! w9 Z, W% V5 D6 ?: |4 pwhere k, b, and c are constants resulting from curve fitting to the IPC-2221 curves
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; k+ W; B% J1 E b$ P QPCB VIA calculator ' g. w5 l/ _6 | v& ` g2 ?
Resistance = Resistivity*Length/Area 1 {( k% V+ q+ b+ i: Y D" Z) ]
Area = pi*(Inner_dia + Plating_thk)*Plating_thk
( u& }3 V- Y) k5 aResistivity = 1.9E-6 Ohm-cm (plated copper) 4 O4 e- e: I. l4 o% o: e4 H
(plated copper is much more resistive than pure copper)
- l% U/ G/ V5 zCopper Thermal_Resistivity = 0.249 cm-K/W (at 300K) % t, i( K' Q' L9 q$ C3 d
Est_Ampacity [Amps] = k*(Temp_Rise [deg C])^b*(Area [mils^2])^c
6 P4 {. b: n7 ]/ CFor IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725 . E: k5 `# c( ^4 `2 H. ^$ u
我做的一个xls方式的计算式,可以算电流的。
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