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Subject:	Re: RF Assembly Issues
From:	"Sauer, Steven T." <[log in to unmask]>
Reply To:	TechNet E-Mail Forum.
Date:	Mon, 2 Apr 2001 07:51:50 -0400
Content-Type:	text/plain
Parts/Attachments:	text/plain (45 lines)

Morning Marty,
Along with "designed geometries" (knowing what your process should yield), a
"designed reflow profile" should be developed.  Bottom only terminations and
in your case a ceramic component together pose a challenge but not out of
reach.  Without knowing your layout (i.e. location of Xceiver on substrate,
other components, substrate thickness/layer count) several quick changes to
the reflow profile could fix the problem:  change orientation of substrate
entering oven or slow the conveyor.  It's apparent that not enough thermal
energy is being transferred to the solder connections.  To truly understand
the local and global thermal characteristics of the reflow profile, a data
logger with thermocouples should be used.  I would bet  the solder paste at
the Xceiver is liquidous less than 15 seconds (look at the recommended
reflow profile from the solder paste manufacturer -- some recommend above
liquidous 45 - 90 seconds).  If all else fails, require the component to be
hand soldered -- this may cheaper in the long run.

Hope this helps.

Steve Sauer


-----Original Message-----
From: Marty Brooks [mailto:[log in to unmask]]
Sent: Thursday, March 29, 2001 6:12 PM
To: [log in to unmask]
Subject: Re: [TN] RF Assembly Issues


Thanks everyone for your input.

Steve - I think the bottom only terminations of the chip does pose a
problem.  Have other assembly shops had problems with devices like this and
how have they overcome them?  The chip is a ceramic base with gold plated
terminations.

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