Gaby,

There are many possibilities, depending on what electrical parameter the
coil fails (open connection, loss of inductance, or erratic high-frequency
behaviour......? ).If it's simply an open circuit, you may want to check
whether the internal magnet wire connection comes with any strain-relief
(Any wire slack?). Without the relief, the internal connection may break
when the lead is slightly bent. That happens when you clinch the lead prior
to wavesoldering or when the PCB hole-pitch is slightly off.

If the failure has something to do with high-frequency behaviour,
penetration of contaminant is a possible cause. The contaminant tends to
increase the winding capacitance. Measuring the coils resonant frequency
can tell.

Hope it helps!

KK Chin
Artesyn Technologies
47173 Benicia St.,
Fremont, CA94538

http://www.artesyn.com





Gabriela Bogdan <[log in to unmask]> on 01/08/99 09:39:37 AM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
      to Gabriela Bogdan <[log in to unmask]>

To:   [log in to unmask]
cc:    (bcc: KK Chin)
Subject:  [TN] COILS




Hello!
We are wave soldering through hole coils-the molded type-and experienced
a new problem -for us.
They fail during electrical test, regain their properties-eventually-
after applying pressure on the top of the component, or after
resoldering ,or after
desoldering.
The original solder connections are perfect-checked by cross sectioning
of the mounted component on the circuit.
The sectioned component shows bubbles in the molding and  fine cracks
in the area of coil wire soldering to the leads.
Is somebody there who experienced the same problem?
POPCORNING????
Thanks,
Gaby

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