Homebrew PCBs

A little different subject from most message traffic: Anyone know of a 
method to (hopefully easily) determine the copper weight on unetched 
material (probably FR-4)?

In my case, I've collected various pieces of copper clad board but have 
no idea if copper is 1/2 oz., 1 oz, or more.

Thanks,
Don

----- Original Message ----- 

From: "Don Jackson AE5K" <don@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Wednesday, November 05, 2008 2:46 PM
Subject: [Homebrew_PCBs] Determining copper weight


>A little different subject from most message traffic: Anyone know of a 
> method to (hopefully easily) determine the copper weight on unetched 
> material (probably FR-4)?
> 
> In my case, I've collected various pieces of copper clad board but have 
> no idea if copper is 1/2 oz., 1 oz, or more.

Peel off a piece of copper and measure the thickness.

Leon

On Wed, 05 Nov 2008 08:46:08 -0600, you wrote:

>A little different subject from most message traffic: Anyone know of a 
>method to (hopefully easily) determine the copper weight on unetched 
>material (probably FR-4)?
>
>In my case, I've collected various pieces of copper clad board but have 
>no idea if copper is 1/2 oz., 1 oz, or more.

I think you'd have to sacrifice a very small area, and peel the foil
back with a knife.  Measure that thickness, and then compare.

Harvey

>
>Thanks,
>Don

Can you peel up a corner and measure the thickness with a dial
indicator?

Thanks for the suggestion(s) for determining copper weight of some 
copper clad material.  I'll see if the old micrometer can tell me 
something.  All three suggestions were to peel a little piece of the 
foil and measure it.

I wonder if another simple method might be to measure overall thickness 
of unetched material and then subtracting the resultant thickness of 
totally etched (no copper left) material.  (Take into account single or 
double sided.)

I didn't easily find a reference to "ounces versus thickness", so for 
anyone looking, this website has a nice chart:

http://www.standardpc.com/laminates.htm

or here is the info:

1/2 oz.    18 um     0.7 mil
1 oz.      35 um     1.4 mil
2 oz.      70 um     2.8 mil
3 oz.     105 um     4.2 mil

For various thickness of materials, here's the mm to mil conversions:

0.4 mm      16 mil
0.6 mm      24 mil
0.8 mm      32 mil
1.0 mm      40 mil
1.2 mm      47 mil
1.6 mm      63 mil

(OK, no quibbling over round offs!)

If anyone finds a neater form, let me know.  I did spend a lot of time 
looking at this groups resources online and may have overlooked this 
information.

Regards,
Don

Here are the details for Cu thickness & clad weight:
 
Copper Weight: it defines the number of ounce copper on 1 sq. ft. area, such
as 0.5, 1.0, 2.0, 3.0 oz, etc. Usually this parameter is used to specify the
thickness of the copper on each layer of the board. It is very easy to work
out the thickness of 1.0 oz copper on 1 sq. ft. board based on the copper
density (8.9 g/cm3), which is 34.29 µm and rounded up to 35 µm. So we have
the following list.

0.5 oz means 17.5 µm copper thichness
1.0 oz means 35 µm copper thichness
2.0 oz means 70 µm copper thichness

Regards,
 
HughAW

  _____  

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of Don Jackson AE5K
Sent: Wednesday, November 05, 2008 6:46 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Determining copper weight



A little different subject from most message traffic: Anyone know of a 
method to (hopefully easily) determine the copper weight on unetched 
material (probably FR-4)?

In my case, I've collected various pieces of copper clad board but have 
no idea if copper is 1/2 oz., 1 oz, or more.

Thanks,
Don


 


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