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Fri, 9 Apr 1999 13:42:42 -0600 |
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You would use "sticky flux". The same viscous flux that is used in
solder-paste. Contact your Solder Paste Vendor. My impression is they all
sell the stuff now for BGA and flip-chip attach. It is often applied to the
BGA balls by dipping the BGA into a controlled thickness of flux that is
squeegeed onto a surface plate or squeegeed directly onto the board with a
stencil. The BGA attach is done with no-clean for very fine pitch balls. I
don't work at an assembly shop but I believe I've described is actually
being done.
Gary P.
-----Original Message-----
From: Ryan Chase [mailto:[log in to unmask]]
Sent: Friday, April 09, 1999 1:19 PM
To: [log in to unmask]
Subject: Re: [TN] bare boards with solder paste
Is that little bit of flux enough to stop the parts from bouncing off the
PCB? The Y-movements on my Mydata are quite violent and without
the tackiness of the paste the parts would definitely be thrown right
off the PCB.
Ryan
Date sent: Fri, 9 Apr 1999 08:26:35 -0600
Send reply to: "TechNet E-Mail Forum." <[log in to unmask]>,
"Peterson, Gary D" <[log in to unmask]>
From: "Peterson, Gary D" <[log in to unmask]>
Subject: Re: [TN] bare boards with solder paste
To: [log in to unmask]
> I found that the solid solder deposit is terrific for fine pitch parts.
We
> used a commercial process called Precision Pads Technology (PPT) to solder
> mini-bgas we developed in-house. The parts had 10-mil balls on 20-mil
> pitch. They were a breeze to solder with the PPT solder deposits on the
> boards. I also found that the PPT allowed us to solder PLCCs in
Vapor-phase
> Reflow systems (not very popular these days due to the CFC ban) without
all
> of the solder wicking up the leads. I'd use it for all of our boards it
> were up to me ... I'm not sure why it hasn't caught on in the industry.
>
> Gary D. Peterson
> Sandia National Labs
>
> -----Original Message-----
> From: Lustig, Steven K.. [mailto:[log in to unmask]]
> Sent: Thursday, April 08, 1999 4:48 PM
> To: [log in to unmask]
> Subject: [TN] bare boards with solder paste
>
>
> TechNetters,
>
> Does anyone have experience using boards that come in with a form of
> solder paste already on the pad so that all you need to do is apply some
> flux (much less precisely than solder paste application needs to be) and
> then go ahead and place your parts, followed by reflow? My boss has a
> brochure from one of the companies which offers this service and I was
> wondering how well they work.
>
> Thanks.
>
> -Steve
>
> Steven K. Lustig
> Process Engineer
> EMS Technologies, Inc.
> Norcross, GA
> (770) 263-9200 x4714
> [log in to unmask]
>
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-----------------------
Ryan Chase
Manufacturing Engineer
GE Harris
403-214-4502
Fax 403-287-3107
[log in to unmask]
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847-509-9700 ext.312
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