Peter,
There is a similar device called the Huntron meter that is also an
excellent electronics test/troubleshooting tool. It is similar to a
curve tracer, but applies an extremely low current/low voltage source
through the ground plane. Every portion of the circuit that is
accessible can be tested. With the ground connected, you can read the
component's "signature" with the positive probe, or you can
automatically scan all of the nodes using a small fixture. A known-good
unit is used, or you can have it establish reference patterns by
averaging. A forward-biased diode has a waveform shaped like a chair,
for example. An inductor is a circle or oval, depending on the value.
This can be used to quickly scan all of a particular component's leads,
or you can use it for checking the assembly itself. It is very useful
for testing BGAs prior to assembly or upon removal without having to
power it up. No electronics shop should be without one. Check it out at
www.huntron.com
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of
[log in to unmask]
Sent: Wednesday, July 20, 2005 10:40 AM
To: [log in to unmask]
Subject: Re: [TN] Component Failure analysis
Peter,
After you've done the preliminary x-ray looksee .. curve tracing is
another very useful, first pass, non-destructive way to gain some
insight as to what's going on with a part. It won't necessarily tell you
what the root cause of the failure is, but the waveforms displayed by
tracing pin-pin, pin-rail, pin-gnd, etc., will reflect any opens,
shorts, leakages and other unusual conditions in the device. This is all
helpful information in the FA process.
One drawback is that a curve tracer will see everything else in the
circuitry that is on the same net as the pins you're interested in,
which can add a good bit of confusion to the interpretation of the
waveforms. In an ideal situation, the part is powered up (VCC-GND), and
your pins are isolated from the outside world. It can be performed on
the board, but it requires careful attention to C/T stimulus voltage,
currents, and technique. It's a snap for parts already removed from the
board.
It is often helpful to perform the same curve trace analysis on a known
good part so you have those waveforms to compare against those of your
failed part. If you have multiple vendors for this part, stay with the
same vendor and die rev. for the comparison.
Any outside lab will have a curve tracer.
Bruce Tostevin
Benchmark Electronics
Hudson, NH
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Peter Lee
Sent: Tuesday, July 19, 2005 1:58 AM
To: [log in to unmask]
Subject: [TN] Component Failure analysis
Technet,
What are possible failure analysis (destructive or non-destructive and
what are the pro/cons) I could conduct on the component level (of an IC)
to determine failure mode/root cause?
We are measuring internal shorts between leads on a SOIC after
soldering.
Troubleshooting has pointed towards that failure is component (not
soldering
process) related. I am looking for an independent lab that can offer
such service.
Rgds,
Peter
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