Kathy,

My company has been doing quite a bit of research into this area lately.  We've
been using an Omega meter to perform contamination measurements of our
system for quite a while.  However, we have become aware that the mixture
used in an Omega meter is not particularly effective at dissolving OA flux.

We have investigated SIR testing, but do not feel that it will provide the process
information that we need.  It can only be performed on boards that were
designed with an SIR test pattern in it.  An SIR test pattern is a series of
interlaced traces.  When you put a potential across these traces, you will
promote dendritic growth.

The most promising lead we've found is a test procedure that is currently being
developed by IPC.  They are basically trying to develop a test that uses the
Omega meter to measure the ionic contamination but utilizes a different
procedure to facilitate dissolving the flux.  The current procedure that they are
looking at includes:  sealing the board in a bag containing 75% alcohol and 25%
water.  Then you put the bag in a water bath at 80C for an hour.  You then dump
the bag into the Omega meter and measure the contamination level.

We just started looking into this, and we are getting ready to start this testing.
If you like, I would be glad to send you a copy of IPC's preliminary procedure.

Kevin

Kevin Stokes                                                                                             Reliability Supervisor
Acu-Rite Incorporated                                                                         Phone: (716) 661-1836
1 Precision Way                                                                                      FAX:  (716) 661-1793
Jamestown, NY 14701                                                                email:  [log in to unmask]


-----Original Message-----
From:   Kathy Palumbo [SMTP:[log in to unmask]]
Sent:   Monday, June 29, 1998 4:40 PM
To:     [log in to unmask]
Subject:        [TN] Contamination Testing for Water Soluble Flux Residue

I was told that water soluble flux does not leave ionic contaminants behind,
and if you want to test for contaminants you should do a surface Resistivity
test.

My questions are as follows:

1.  Is this entirely true, or can some sort of correlation be made between
the two different types of tests.
2.  If surface Resistivity testing is being done should ionic contamination
testing ever be done?
3.  Are there any Ionic Contamination Testing systems available so we can do
this test in house?
4.  Are there any Surface Resistivity Testing systems available so we can do
this test in house?

Thanks in advance for you responses!

Kathy Palumbo
Viking Components

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