Technetters Hello again;

We are having a problem with a Token crystal oscillator. During the month
of April there was a fallout spike of plus 10% from testing in
manufacturing.  The supplier was contacted and some defective components
returned.  After their evaluation they indicated that the components were
damaged due to over-heating.  They attached a copy of the desired
temperature profile we should be using.

We ran the mole through the oven and came up with the real profile (note,
the thermocouple was attached to the body of the resonator).  They are
having trouble actually interpreting the wording of the spec, especially
when compared to the recommended profile for the solder paste.

The component spec has a cautionary note as follows:  "Heating conditions
shall be within 20 seconds at +230 deg C min, but peak temperature shall
be lower than +240 deg C.  The profile figure shows a breakout above +200
deg C and states the maximum time above 200 should be 20 seconds.  The two
statements together seem confusing and we are asking for some
clarification.

To add confusion to the issue the solder paste spec:  Qualitek 670I
No-Clean Paste (Sn63/Pb37) shows a recommended profile for reflow of
Minimum Temp 205 deg C ranging from approx. 180 deg C with a minimum time
of 60 seconds.  Again it appears using this paste we cannot meet the
component reflow profile?

We then looked at our current profile and found the following:

We are above 200 deg C for about 45 seconds, the peak temperature is 218
deg C.

Any help/comments would be appreciated.




                        P.  Lance Mayes

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------
                        Mfg. Trainer