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Subject:	Re: voids in BGA
From:	Rick Thompson <[log in to unmask]>
Reply To:	TechNet E-Mail Forum.
Date:	Mon, 16 Oct 2000 15:27:41 -0700
Content-Type:	text/plain
Parts/Attachments:	text/plain (49 lines)

Tom,

There was an article in the April 2000 SMT Magazine regarding the benefits
of a Ramp-to-Spike profile. According to the author, voiding generally
results from one of three causes; insufficient peak temperature,
insufficient time at temperature, or excessive temperature in the ramp zone.

Rick Thompson

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Thomas Han
Sent: Monday, October 16, 2000 2:49 PM
To: [log in to unmask]
Subject: [TN] voids in BGA


Hi all,  Customers are finding some opens in the PBGA(292 pin 1.27pitch)
that we installed for them.  X-ray shows good even reflow, but has some
small voids in some of the connections.  The gentleman that took the xray
for us tells me that the voids are caused by moisture in the paste, but
that shouldn't cause opens.  We are running an OA process, and the BGAs are
processed thru PnP and forced convection reflow.  I have increased the ramp
temp and that didn't seem to help.  The profile looks good with reflow of
about 55sec(time above 183C) with max temp at 225C.  The whole profile is
about 4.5min.

Any input is greatly appreciated.

Tom

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