Re: Alloy-42

Nirmal Jain (
Mon, 22 Apr 96 12:23:41 EDT

Hi Steve,

You can model alloy42 leadframes in two ways. One way would be to
get the frequency dependant permeability (mu) data from the
alloy 42 vendor and use that data in the software to get discrete Ls
at different frequencies. This may be time consuming. If the software
is using some analytical expression, it may be fast enough but
may not be very accurate. I am not sure whether this data is available
from the vendors. When I tried to get this data a while ago, was

Another, more popular way is to characterize your leadframe/package
designs for L. Here you would be doing L measurements on Cu and alloy42
leadframes/packages and getting an effective mu for alloy42 and use that in
all your future models.

You can refer to the following papers for further information :-

Hope it helps; Best Wishes


PS At low freq the difference in L between alloy42 and Cu
is pretty significant. May be by a factor of ten at couple of
MHz. Alloy42 L is 10-20% higher than Cu at few hundred MHz.

Electrical Characterization and modeling of SSN for Leadframe packages.
Masayuki Miura, Naohiko Hirano, Yoichi Hiruta and Toshio Sudo
Toshiba Corp, Japan.


HF L measurement and characterization of Alloy42 and Cu packages.
W-Y Yip, C-T Tai, A. Sparkman, R Sharma and H. Astrain
43rd ECTC, 635-640

>I'm looking for information on models of packages with Alloy-42
>(feromagnetic) leadframes.
>Any information on modeling techniques, software packages used,
>or sample data would be appreciated.
>I would also be interested if anyone has modeled the same package
>with both Alloy-42 and copper leadframes and can comment on the
>relative differences.
>Steve Majors
>Harris Semiconductor

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