Luis,
You are correct that there can be a difference in voiding between the RTS and RSS profiles.
However, in our experience this difference is not nearly as significant as that found when
implementing the LSP profile.
I will send the LSP settings to you separately as this listserv does not accept attachments.
The trials you reference were performed with a water soluble solder paste because this was
considered to be the worst case scenario for voiding. All of our experience and empirical data
shows that the results of implementing the LSP profile is an elimination/reduction of voids when
utilizing ANY type of solder paste, no-cleans (and AIM's 293) included.
Regards,
David Suraski
AIM
----- Original Message -----
From: "Luis Gallegos" <[log in to unmask]>
To: "'TechNet E-Mail Forum.'" <[log in to unmask]>; "'David Suraski'" <[log in to unmask]>
Sent: Wednesday, January 28, 2004 11:31 AM
Subject: RE: [TN] PBGA Void/pin holes
> David
> There is differences on the profiles (RSS & RTS) What is the settings for
> the LSP profile?.
> My next question is. the results are base on a water soluble paste, would it
> be different for the NC293?.
>
>
> thank you
>
> -----Original Message-----
> From: David Suraski [mailto:[log in to unmask]]
> Sent: Wednesday, January 28, 2004 8:44 AM
> To: [log in to unmask]
> Subject: Re: [TN] PBGA Void/pin holes
>
>
> Dear Luis,
>
> I am going to briefly discuss voiding from our perspective. For additional
> information I encourage
> you to visit our more detailed article on this topic located at
> http://www.aimsolder.com/techarticles/tech%20sheet%20BGA%20voiding-%20reduci
> ng%20through%20process%20optimization.pdf
>
>
>
> There is still a debate as to the negative effects of voids. In general,
> large voids that take up a
> high percentage of the volume of the joint are considered problematic.
> These voids are more likely
> to have a more significant effect on the mechanical integrity and heat
> dissipation ability of the
> solder joint. Smaller, evenly dispersed voids that take up a lower
> percentage of the volume of the
> joint are often considered "normal" and non-problematic. I'm sure that
> others can comment more on
> this.
>
>
>
> Voiding can be impacted by the materials in use as well as the SMT process.
> In our experience
> voiding under BGAs can be significantly reduced through process
> optimization.
>
>
>
> Handling- If BGAs are not stored and handled property a variety of
> processing defects can occur,
> including voiding and popcorning. The key is to follow the manufacturers
> recommendations regarding
> moisture levels, baking, storage time, etc. A common practice is to bake
> BGAs and vacuum seal them
> with a bag of desiccant in a Mylar bag.
>
>
>
> Printing- BGA solder defects are often traceable to the printing operation.
> If the printing is
> mis-registered, or if the volume printed is insufficient, it is likely that
> the resulting BGA solder
> joints will not have the desired integrity. For this reason, it is
> imperative that printing
> equipment be properly calibrated, set-up and verified. 100% inspection of
> printed BGA sites may be
> required prior to placement to verify paste coverage, uniformity, and
> volume.
>
> Reflow Profiling- Two types of reflow profiles are most commonly utilized
> when reflowing SMT
> assemblies: Ramp-Soak-Spike (RSS) and Ramp-to-Spike (RTS). Optimizing these
> profiles per the solder
> paste manufacturer's guidelines can help to reduce voiding. In addition,
> one can also utilize the
> "LSP" (low soak profile) profile, which has proven to significantly reduce
> voiding when used in
> conjunction with several types of BGA components. The success of the LSP
> profile lies in its
> ability to dry out the solvent of solder paste before the reflow zone. I'll
> be happy to send
> additional info on the LSP profile to you if you like.
>
>
> Regards,
>
> David Suraski
>
> [log in to unmask]
> AIM
> +1-401-463-5605
> www.aimsolder.com
>
>
>
> > -----Original Message-----
> > From: Luis Gallegos [mailto:[log in to unmask]]
> > Sent: Monday, January 26, 2004 10:02 AM
> > To: [log in to unmask]
> > Subject: [TN] PBGA Void/pin holes>
> >
> > Good morning Technetters.
> > I am having some occasionally voids/pin holes on our PBGA. We are
> currently
> > using NC293 Sn63/Pb37 Aim solder paste. The board is silver plated.
> Printing
> > with a 6 mil stencil.
> > Is it normal to have occasionally voids?
> > We have bake our PBGA's prior to reflow, and also work with the oven
> > profile. Any suggestions.
> > Thank you
> >
> > Luis A Gallegos
> > Automation Senior Technician
> > SANMINA-SCI
> > Pleasant Prairie WI
> > Phone: 262 947-7700
> > [log in to unmask]
> >
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