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October 2001

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Subject:
From:
"Franck, George" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 10 Oct 2001 13:05:03 -0400
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For a First order Approximation, use the Charts in the IPC-2221 Fig 6-4
"Conductor thickness and width for internal and external layers".

.....  Where
 the copper foil thickness in Fig 6-4. = plating thickness in the hole.

 the Conductor width in Fig 6-4. =  hole dia. * pi (3.141)

Example, Can a 13 mil hole with 1 mil copper plating carry one Amp?

Conductor width is 13* 3.1 = 40 mil
Conductor thickness is 1 mil

Using Fig B (of Fig 6.4):
Cross section in Sq. Mils = 30  (about that anyway)

Using Fig C (of Fig 6.4) Internal conductors:
An internal conductor of 30 Cross section in Sq. Mils will carry 1 amp and
experience a 20 deg C temperature rise.

Answer:  A 13 mil hole with 1 mil copper plating will carry one Amp in most
applications.

For all the derating these charts have seen, this should give you a
conservative answer.  We use this approach to determine the number of laser
vias needed to run power from one layer to the next.  Using it, we have not
had any problems.  On the other hand, we have not made any measurements, so
there is no supporting data.  Just a warm feeling, ..... about 20 deg C.

George Franck, CID
who is hoping to be a CID++


-----Original Message-----
From: Estrada, Roland [mailto:[log in to unmask]]
Sent: Wednesday, October 10, 2001 11:30 AM
To: [log in to unmask]
Subject: Re: [TN] current carrying capacity of PTH


Filled with the lead?
Vias?
Clad Copper thickness?
Plated Copper thickness of the hole by Class 1, 2 or 3?

Lots of questions to look at. I don't know of any charts.
You could calculate this to a certain condition by the circumference of the
nominal hole size, then by the thickness of the board. This would give you a
flat pattern of this area (X and y) then use the standard IPC current charts
from there.

Roland Estrada CID
Lockheed Martin - Dallas

-----Original Message-----
From: Geoff Layhe [mailto:[log in to unmask]]
Sent: Wednesday, October 10, 2001 8:41 AM
To: [log in to unmask]
Subject: [TN] current carrying capacity of PTH


Hi All,
Does anyone have information such as formula, graphs etc  regarding current
carrying capacity of plated through holes?

TIA
Geoff Layhe
www.lamar-uk.co.uk


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