Steve,

First, thanks for the heads up.

Did Coil Craft say that the problem extended to any other product lines?

Are the inductors cracking in the assembly process (i.e. due to the heat encountered
in the soldering and other processes), or are they cracking during actual use?

Based on the picture, I would say that the cracking appears limited to the "case" or
shield, but that may not be the case in every instance. Did Coil Craft say whether
or not the crack in the "case" affected the coils electrical performance or the
shielding capability?

Notwithstanding Coil Craft's admission of a problem, I would still ask the following
two questions.

Are you possibly cooking these puppies a little too much during a Lead Free
soldering process with possibly an improper profile?

If they are cracking in use, I would think that an additional engineering evaluation
would be in order just to make sure that there wasn't too much current being pumped
thru the inductors which could cause them to heat up far beyond their intended
design use or anything encountered during the assembly process.

As a side issue, I just couldn't help but notice that the two diodes shown in the
picture happen to be packaged such that when oriented with the case positioned so
that the part number text was "right reading" that there are two "polarity
indicators", a notch and a band, obviously both identifying the Cathode, and that
the "polarity indicators" are on the left. These guys must have been anticipating
IPC-7351.  ;^)

Just out of curiosity, one can not help but notice all of the bright shinny vias in
the picture, are they unprotected bare copper?

JaMi



----- Original Message -----
From: "Steve Gregory" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, October 29, 2004 2:04 PM
Subject: [TN] Cracked Cases on SMT Power Inductors from Coil Craft...


> Hi All!
>
> I just discovered a problem with some SMT Coil Craft Power Inductors, it's their
MSS1260 series. The problem is that the cases are cracking. I don't know if any of
you have experienced this, or know anything about this issue, so I thought I would
share what I just learned this afternoon. Take a look at:
>
> http://www.stevezeva.homestead.com/files/CrackedCoil.jpg
>
> We just discovered these on assembled product..naturally :^(
>
> I called Coil Craft and spoke with their Quality representative, and they said
that they are aware of the issue, and have changed their assembly processes back on
September 16th to address the issue.
>
> The reason that the coil cases were cracking, was because they were filling the
entire cavity between the surface of the winding around the coil, and the inside
surface of the case with potting compound. During subsequent heating, the expansion
of the potting compound would stress the case and cause it to crack. I was told that
inductors made after September 16th would only have potting compound in the
> corners to allow for expansion.
>
> So if any of you have any of these sitting around in your stockroom, I wouldn't
use them without inspecting them to see if the cavity is completely full of potting
compound.
>
> -Steve Gregory-
>
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