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本帖最后由 dbit 于 2011-10-7 16:40 编辑
- ?. M, K2 |3 i/ J' e123456sz 发表于 2011-10-5 00:30 ![]()
1 l4 E5 K" O: s8 L/ d更改铜厚没有反应
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7 F2 T( r( M" v/ k- o4 p1 }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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所有计算依据:IPC-2221标准制定;
1 i" Q2 B% k$ ?' LIPC-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:
' g- @) \1 n g6 p0 O7 m" P hGeneric Standard on Printed Board Design. |/ q/ C) }# ~
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trace width calc: y4 ~. Q, \% Q C, ?* C1 m9 }: g
Area[mils^2] = (Current[Amps]/(k*(Temp_Rise[deg. C])^b))^(1/c)
+ {8 C5 x4 N9 i3 \4 z% _, Y% uThen, the Width is calculated:
# T4 m( f% w' ?' W+ L, S! v3 |Width[mils] = Area[mils^2]/(Thickness[oz]*1.378[mils/oz]) 5 U: w9 v1 |! h7 Q1 Z" c
For IPC-2221 internal layers: k = 0.024, b = 0.44, c = 0.725
, \0 J' [$ ^4 W: U' Y* T% {' sFor IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725 ( \. f; H9 G$ G6 o$ O+ q
where k, b, and c are constants resulting from curve fitting to the IPC-2221 curves i Y4 |' L6 Q4 f/ m
/ c! g2 Z: @' {7 ^3 w2 ~PCB VIA calculator
3 \) u& y9 G' F: }. XResistance = Resistivity*Length/Area
( m. A( P6 _ }$ `Area = pi*(Inner_dia + Plating_thk)*Plating_thk
2 ~0 Q/ ?4 A6 ?4 sResistivity = 1.9E-6 Ohm-cm (plated copper)
+ l4 Q! d, P. p+ f" y$ Y(plated copper is much more resistive than pure copper)
! ]' T# o2 h: P" L0 G8 r% B8 eCopper Thermal_Resistivity = 0.249 cm-K/W (at 300K) ; O/ S- m4 t. o. v G/ N( M) f! _' f
Est_Ampacity [Amps] = k*(Temp_Rise [deg C])^b*(Area [mils^2])^c ) ~ Y9 S, a5 G2 v: n/ A/ D! f# G
For IPC-2221 external layers: k = 0.048, b = 0.44, c = 0.725
. S" t6 V% m, Q* G% ]我做的一个xls方式的计算式，可以算电流的。! D- x; f0 m# M' X0 C
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发表于 2011-7-25 09:32
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