Re: [SI-LIST] : Equivalent Conductivity of Inner Copper layer in PCB?

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From: jrbarnes@lexmark.com
Date: Tue Oct 31 2000 - 15:03:29 PST


Jason,

IPC-D-317A Design Guidelines for Electronic Packaging Utilizing High-Speed
Techniques gives:

MAXIMUM RESISTIVITIES FOR COPPER
copper thickness maximum resistivity
---------------------- --------------------
E 0.181 ohm-gram/m^2 electrodeposited
Q 0.171 ohm-gram/m^2 electrodeposited
T 0.170 ohm-gram/m^2 electrodeposited
H 0.166 ohm-gram/m^2 electrodeposited
M 0.164 ohm-gram/m^2 electrodeposited
1 ounce and greater 0.162 ohm-gram/m^2 electrodeposited
type 5 0.158 ohm-gram/m^2 rolled wrought
type 6 0.153 to 0.157 ohm-gram/m^2 light cold rolled wrought
type 7 0.152 ohm-gram/m^2 annealed wrought
type 8 0.158 ohm-gram/m^2 as rolled wrought

IPC-MF-150F Metal Foil for Printed Wiring Applications gives:

maximum resistivity for untreated copper foil

copper thickness maximum resistivity @ 20C
---------------------- -----------------------------------
E 0.181 ohm-gram/m^2 electrodeposited
Q 0.171 ohm-gram/m^2 electrodeposited
T 0.170 ohm-gram/m^2 electrodeposited
H 0.166 ohm-gram/m^2 electrodeposited
M 0.164 ohm-gram/m^2 electrodeposited
1 ounce and greater 0.162 ohm-gram/m^2 electrodeposited
type 5 0.160 ohm-gram/m^2 wrought
type 6 0.155 to 0.160 ohm-gram/m^2 wrought depending on temper
type 7 0.155 ohm-gram/m^2 wrought
type 8 0.160 ohm-gram/m^2 wrought

IPC-2222 Sectional Design Standard for Rigid Organic Printed Boards defines:

nominal weight of copper foil (Class I +/-10%, Class II +/-5% by weight):
* E = 1/8 ounces per square foot
* Q = 1/4 ounces per square foot
* T = 3/8 ounces per square foot
* H = 1/2 ounces per square foot
* M = 3/4 ounces per square foot
* 1 = 1 ounces per square foot
* 2 = 2 ounces per square foot
* 3 = 3 ounces per square foot
* 4 = 4 ounces per square foot
* 5 = 5 ounces per square foot
* 6 = 6 ounces per square foot
* 7 = 7 ounces per square foot
* O = unclad
* X = weight not expressed by single digit

Printed Circuit Engineering (Raymon H. Clark, Van Nostrand Reinhold, 1989)
defines:

copper thickness internal layer thickness after processing
----------------- -----------------------------------------
1/8 ounce E 3.5um
1/4 ounce Q 6.0um
3/8 ounce T 8.0um
1/2 ounce H 12.0um
3/4 ounce M
1 ounce 25.0um
2 ounce 56.0um
3 ounce 91.0um
4 ounce 122.0um
5 ounce
6 ounce
7 ounce
>4 ounce minimum foil thickness in IPC-MF-150 minus 13um

base copper thickness external layer thickness after processing
--------------------- -----------------------------------------
1/8 ounce E 20um
1/4 ounce Q 20um
3/8 ounce T 25um
1/2 ounce H 33um
3/4 ounce M
1 ounce 46um
2 ounce 76um
3 ounce 107um
4 ounce 137um
5 ounce
6 ounce
7 ounce
>4 ounce for each additional ounce increase minimum
                        thickness by 30um

MIL-S-13949H Amendment 1 Military Specification Sheet, Printed Wiring Board
General Specification for, and its slash sheets define:

nominal weight of copper foil (Class I +/-10%, Class II +/-5% by weight):
* E = (1/8) 0.146 ounces per square foot 0.0002" 0.005mm
* Q = (1/4) 0.263 ounces per square foot 0.0004" 0.009mm
* T = (3/8) 0.350 ounces per square foot 0.0005" 0.012mm
* H = (1/2) 0.50 ounces per square foot 0.0007" +/-0.00007" 0.0175 +/-0.00175mm
* M = (3/4) 0.75 ounces per square foot 0.0010" +/-0.00010" 0.025 +/-0.0025mm
* 1 = (1) 1.00 ounces per square foot 0.0014" +/-0.00014" 0.035 +/-0.0035mm
* 2 = (2) 2.00 ounces per square foot 0.0028" +/-0.00028" 0.070 +/-0.0070mm
* 3 = (3) 3.00 ounces per square foot 0.0042" +/-0.00042" 0.105 +/-0.0105mm
* 4 = (4) 4.00 ounces per square foot 0.0056" +/-0.00056" 0.140 +/-0.0140mm
* 5 = (5) 5.00 ounces per square foot 0.0070" +/-0.00070" 0.175 +/-0.0175mm
* 6 = (6) 6.00 ounces per square foot 0.0084" +/-0.00084" 0.210 +/-0.0210mm
* 7 = (7) 7.00 ounces per square foot 0.0098" +/-0.00098" 0.245 +/-0.0245mm
* O = unclad
* X = weight not expressed by single digit

Previous discussions on this forum have concluded that surface roughness does
not have a
significant effect on the conductivity/resistivity of copper until you exceed
1-2GHz or so.

                                              John Barnes Advisory Engineer
                                              Lexmark International

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