Perhaps your capacitor problem has nothing to do with your processes.
The caps may be blowing due to voltage transients on the input when
power is applied. Have you checked on this?


James Sams
Board Designer
Alliant Techsystem, Inc.
401 Defense Hwy.
Annapolis, MD 21401
Tel: 410-266-1837
e-mail: [log in to unmask]



> ----------
> From:         Pierce Pat[SMTP:[log in to unmask]]
> Sent:         Thursday, December 04, 1997 9:45 AM
> To:   [log in to unmask]
> Subject:      [DC] SMD Capacitor Cracking
>
> We are a company new to SMT and are working on a design in which a
> 500V
> Ceramic capacitor with a 1206 pkg. size has an initial 115VAC input
> voltage applied to it. On 50% (5 of 10) units tested, the capacitor
> "blew
> up" (The design works on the 5 that didn't "blow up").  We are no
> where
> near the limits of the device and believe that the capacitors are
> cracking at some point in the assembly process. What I am looking for
> is
> all the possibilities for this occurrence.
> Some additional info: the board size is .407"x2.075", FR4, .031 thick,
> single sided. Assembled in a 7x4 array (28up), scored, panel size
> 3.5"x8.9". Placed in the reflow oven, the capacitor goes in last (at
> end
> of PCB). Thank You in advance!
>
> ##############################################################
> IPC Designers Council Mail List provided as a free service by IPC
> using LISTSERV 1.8c
> ##############################################################
> To subscribe/unsubscribe, send a message to [log in to unmask] with
> following text in the body:
> To subscribe:   SUBSCRIBE DESIGNERCOUNCIL <your full name>
> To unsubscribe:   SIGNOFF DESIGNERCOUNCIL
> ##############################################################
> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
> additional information.
> For the technical support contact Dmitriy Sklyar at [log in to unmask] or
> 847-509-9700 ext.311
> ##############################################################
>

##############################################################
IPC Designers Council Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE DESIGNERCOUNCIL <your full name>
To unsubscribe:   SIGNOFF DESIGNERCOUNCIL
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information.
For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311
##############################################################