Rudy- I'm providing some more information that may be of help. (Any SIR
information provided by industry suppliers should be gathered using an industry
accepted IPC Test Method or equivalent.) I'd also wish to thank you for your
many contributions to TechNet over the years.

(1.) We first presented the data on our fusing fluid work as paper NWC TP
6789 & IPC-TP-719 in 1987 & 1988 respectively, with an expanded  version
available later.  The expanded version includes the  quantitative measurement of the
organic contamination levels plus the  ionic levels, all data obtained on
identical single fabrication batch test PWBs.  SIR and electromigration resistance
data are also included. Data is provided on  both IR fused and unfused
(control) boards. These papers included data on  a new water insoluble fusing fluid
that afforded higher SIR values. This new  technology was rejected by the PWB
industry since they were locked in to use  post-fusing water wash processes.

(2.) You may also find the work done by Boeing presented in 1981
(IPC-TP-383) of interest, as it shows the effect of developing test methods and  removal
methods to clean off organic contamination from the PWAs that permited  them
to pass Mil second level testing. That was our first clue that organic  fusing
fluid contamination was involved in degrading SIR to unacceptable  levels.

(3.) The first time two SEM labs identified lead oxide (not lead chloride)
as responsible for degrading SIR can be found in IPC-TP-135 (1976) as well as
reprinted in one of the 1977 IPC Tech Reviews. (The lead was removed by a
unique method described in the paper. In subsequent years, the lead
identification cast from this paper was used to monitor the presence of lead  oxide on
other problem PWAs. As more information was gained, the paper was  expanded.
In this case reversible telecom circuit failure was directly related  to
humidity level. Raise the humidity, PWAs fail. Lower the humidity and the  PWAs
work just fine. In this case a method was found to identify and cure the
problem to restore the PWAs to proper field performance life.

(I have copies of the various papers/versions noted above in my hard  copy
files plus a draft of the lead test method.)

Bill  Kenyon
Global Centre Consulting
3336 Birmingham Drive
Fort Collins, CO  80526
Tel: 970.207.9586 Cell: 970.980.6373
email:  [log in to unmask]


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