Last thought on this topic:

Over the past 18 months, CALCE has seen a significant increase in ceramic
capacitor failures (thermal shock cracks, flex cracks, manufacturer flaws)
among its customers. In terms of pure speculation, its possible that the
huge demand for capacitors during the boom may have lead to some relaxation
in process control.

What this implies is that your process was borderline to begin with, and
then the addition of caps with larger flaws or a lower fracture toughness
simply lead to the introduction of failures where there were none before.

Best Regards
Craig


-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Bartkowaik Christine
Sent: Friday, August 17, 2001 6:56 AM
To: [log in to unmask]
Subject: Re: [TN] To wave or not to wave, that is the question...


Kevin:

We have no problem with 1uf caps (TANT). Thus I suspect:
1-      thermal shock
2-      too long a time in the wave >2 s

I would not suspect moisture if the boards have already been thru a reflow
oven and have not sat long.

Chris

        -----Original Message-----
        From:   Kevin Stokes [SMTP:[log in to unmask]]
        Sent:   Thursday, August 16, 2001 4:26 PM
        To:     [log in to unmask]
        Subject:        [TN] To wave or not to wave, that is the question...

        Old problem: mounting ceramic capacitors to the bottom side of an
assembly and your customer wants you to wave them on.

        We are having problems with 0805 0.22 uF and 0.1 uF caps going
through wave and cracking during the process.  We are following all of the
standard protocols (preheat, etc.).  My understanding is that 0805s are
typically capable of handling this process.

        Anyone got any ideas short of moving the cap to the top or doing a
double sided reflow?

        Kevin

        Kevin Stokes
        Reliability Manager
        Kimball Electronics Group
        (812) 634-4207


----------------------------------------------------------------------------
-----
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
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 delivery of Technet send the following message: SET
Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
----------------------------------------------------------------------------
-----

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
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 delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------