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August 2012

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Subject:
From:
Guy Ramsey <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Guy Ramsey <[log in to unmask]>
Date:
Thu, 16 Aug 2012 10:34:16 -0400
Content-Type:
text/plain
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text/plain (82 lines)
We are doing 1.5mm by 1mm with 4 mil stencil 20um-38um spheres SAC305
without significant issues. 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Amol Kane
(Asteelflash,US)
Sent: Thursday, August 16, 2012 10:04 AM
To: [log in to unmask]
Subject: Re: [TN] CSP BGAs

Hello Richard,
So you are talking flux only attachment?......I carefully added flux with a
manual dispenser and a fine gauge syringe after printing and placement on
some test vehicles and the BGA did solder (brushing flux BEFORE printing
does not help as the paste deposit does not stick to the pads). However we
will be building hundreds of these assemblies and I need a repeatable
process. There was flux voiding based on the amount of flux each part got. 

I just wanted to validate my hypothesis about the HIP and graping on such
tiny components and see if anybody was already using dip fluxers for such
components

Thanks!
Amol


-----Original Message-----
From: Stadem, Richard D. [mailto:[log in to unmask]]
Sent: Thursday, August 16, 2012 9:51 AM
To: TechNet E-Mail Forum; Amol Kane (Asteelflash,US)
Subject: RE: CSP BGAs

Simply brush a very thin layer of a good tacky flux such as Alpha WS1208
over the pads prior to placement. Even a very thin layer of this flux will
be more than enough to allow good wetting to the pads.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Amol Kane
(Asteelflash,US)
Sent: Thursday, August 16, 2012 8:34 AM
To: [log in to unmask]
Subject: [TN] CSP BGAs

Dear Technetters,

We are going to be assembling some lead-free  1.6x0.8 mm micro BGAs with
0.5mm pitch and 0.17mm dia board pads. Anybody else have experience with
this small a package?....I am concerned that there won't be sufficient flux
in the tiny solder deposit to clean the oxides during reflow, leading to
graping and/or head in pillow situation. Do I need a dip fluxer for the part
to do a flux only attachment, or to augment the amount of flux in the
solderpaste-solder bump system? I am told I have no time to do DOEs to
determine stencil and reflow parameters, so I am turning to technet for
help.....any thoughts?

 

 

Regards,

Amol

 


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