Homebrew PCBs

Hi Guys,

I buy all my PCBs from "Surplus" dealers. Now that I have a bit of 
collection going AND that some of my designs are getting a bit 
more "powerful", the weight of copper is getting important.  Does 
someone know what the thickness of copper is for the different weights?

Example 1 oz. copper is .001" thick or something similar

Thanks

Chris

Hi Chris,

Try this URL 
http://www.streamlinecircuits.com/streamline/pg_thickResist.shtml

Your guess was pretty close; 0.0014" for 1 ounce copper cladding.  
The 1 ounce info is correct (I've seen that number before), the half 
ounce thickness in microns is wrong; should be closer to 18um.  And 
the first entry is 0.125 ounce, not 125...

Regards,
Dennis

--- In Homebrew_PCBs@yahoogroups.com, "lcdpublishing" 
<lcdpublishing@...> wrote:
>
> Hi Guys,
> 
> I buy all my PCBs from "Surplus" dealers. Now that I have a bit of 
> collection going AND that some of my designs are getting a bit 
> more "powerful", the weight of copper is getting important.  Does 
> someone know what the thickness of copper is for the different 
weights?

> 
> Example 1 oz. copper is .001" thick or something similar
> 
> Thanks
> 
> Chris

Thanks much Dennis - that's what I was looking for!

Chris



--- In Homebrew_PCBs@yahoogroups.com, "dl5012" <dl5012@...> wrote:
>
> Hi Chris,
> 
> Try this URL 
> http://www.streamlinecircuits.com/streamline/pg_thickResist.shtml
> 
> Your guess was pretty close; 0.0014" for 1 ounce copper cladding.  
> The 1 ounce info is correct (I've seen that number before), the 
half 
> ounce thickness in microns is wrong; should be closer to 18um.  
And 
> the first entry is 0.125 ounce, not 125...
> 
> Regards,
> Dennis
> 
> --- In Homebrew_PCBs@yahoogroups.com, "lcdpublishing" 
> <lcdpublishing@> wrote:
> >
> > Hi Guys,
> > 
> > I buy all my PCBs from "Surplus" dealers. Now that I have a bit 
of 
> > collection going AND that some of my designs are getting a bit 
> > more "powerful", the weight of copper is getting important.  
Does 

> > someone know what the thickness of copper is for the different 
> weights?
> > 
> > Example 1 oz. copper is .001" thick or something similar
> > 
> > Thanks
> > 
> > Chris
>

--- In Homebrew_PCBs@yahoogroups.com, "lcdpublishing"
<lcdpublishing@...> wrote:
>
> Hi Guys,
> 
> I buy all my PCBs from "Surplus" dealers. Now that I have a bit of 
> collection going AND that some of my designs are getting a bit 
> more "powerful", the weight of copper is getting important.  Does 
> someone know what the thickness of copper is for the different weights?
> 
> Example 1 oz. copper is .001" thick or something similar
> 
> Thanks
> 
> Chris
>
I saw the following on a web site and wanted to follow thru on the
math, so here it is:

Density of copper is 8.94 grams / cc. (cc = cm * cm * cm)
Recall that there are 454 grams per pound (3 places, rounded)

Thickness in um = 
    0.5 * 10000           454
---------------------- * ---- = 17 um
2.54 * 2.54 * 16 * 144   8.94

Some of the numbers used (for reference):
0.5 = ounces/sq-foot (amount of copper)
10000 = um/cm (microns per cm)
2.54 = cm/inch
16 = ounces/pound
144 = square inches/square foot

It boils down to:
oz/sq-ft * 34.16 = micron thickness 
   (applying a 25.4 um/mil conversion)
oz/sq-ft * 1.34 = mills thickness (thousandth of inch)

A calculator program comes in handy to figure this out, along with
some unit analysis to make sure it all fits.

I saw other references, but this "formula" seems to have some basis on
it.  If some of the constants are wrong, feel free to correct them. 
One reference indicates a density of 8.92 grams / cc for copper.

As a side note, sometimes I hear on _This Old House_ (the PBS TV show)
the rain gutter workers refering to 20 oz copper stock.  Turns out
that those guys measure it the same way, so it is probably a copper
industry standard.  I suspect that 1 oz copper wouldn't work in that
application.

Hopefully this will help someone.

On Thu, 31 Aug 2006 21:06:53 +0200, lcdpublishing  
<lcdpublishing@...> wrote:

> Hi Guys,
> I buy all my PCBs from "Surplus" dealers. Now that I have a bit of
> collection going AND that some of my designs are getting a bit
> more "powerful", the weight of copper is getting important.  Does
> someone know what the thickness of copper is for the different weights?
> Example 1 oz. copper is .001" thick or something similar
> Thanks
> Chris


1oz/sq ft is 35um
0.5oz/sq ft is 18um
2oz/sq ft is 70um

1um is 10^-6m.

ST

On Fri, 01 Sep 2006 00:18:05 +0200, herby1620 <herby1620@...> wrote:

> Thickness in um =
>     0.5 * 10000           454
> ---------------------- * ---- = 17 um
> 2.54 * 2.54 * 16 * 144   8.94
> Some of the numbers used (for reference):
> 0.5 = ounces/sq-foot (amount of copper)
> 10000 = um/cm (microns per cm)
> 2.54 = cm/inch
> 16 = ounces/pound
> 144 = square inches/square foot



I certainly know _why_ i love the SI! That's just frightening...

I certainly also love google - enter the following line as a search term:

8920kg/m^3*1ft^2*35micrometer in oz

and you get

1.0230976 ounces

The good thing about google calculator is it can deal with units and do  
the conversions for you. And if you have a mistake in the formula, like  
divide somewhere instead of multiplying, the result will just not come out  
in the correct unit. If i do that on paper i need to engage brain to check  
that....
Sadly it does not (yet) know the density of copper automatically it seems.


ST

Google is cool!  I am going to have to experiment more with that 
function of it.  




--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@...> wrote:
>
> On Fri, 01 Sep 2006 00:18:05 +0200, herby1620 <herby1620@...> 
wrote:
> 
> > Thickness in um =
> >     0.5 * 10000           454
> > ---------------------- * ---- = 17 um
> > 2.54 * 2.54 * 16 * 144   8.94
> > Some of the numbers used (for reference):
> > 0.5 = ounces/sq-foot (amount of copper)
> > 10000 = um/cm (microns per cm)
> > 2.54 = cm/inch
> > 16 = ounces/pound
> > 144 = square inches/square foot
> 
> 
> 
> I certainly know _why_ i love the SI! That's just frightening...
> 
> I certainly also love google - enter the following line as a 
search term:
> 
> 8920kg/m^3*1ft^2*35micrometer in oz
> 
> and you get
> 
> 1.0230976 ounces
> 
> The good thing about google calculator is it can deal with units 
and do  
> the conversions for you. And if you have a mistake in the formula, 
like  
> divide somewhere instead of multiplying, the result will just not 
come out  
> in the correct unit. If i do that on paper i need to engage brain 
to check  
> that....
> Sadly it does not (yet) know the density of copper automatically 
it seems.

> 
> 
> ST
>