Hi Bob - in our testing, the package preformed better using a lead-free
temperature reflow profile - we had much less warpage and other associated
temperature impacts which we attributed to the package designers optimizing
their package construction characteristics for a lead-free reflow
temperature profile (its a lead-free part, so most frequent use would be in
a lead-free process). We were using a 12 zone oven so lots of room to
profile creation - how many zones in your oven?

As for VP - I have never put a BGA in a VP process yet. It should work
provided the condensing VP fluid doesn't cause the BGA to physically move.

Dave

On Mon, Jan 23, 2017 at 1:48 PM, Bob Wettermann <[log in to unmask]> wrote:

> Hi Dave:
>
> This is SAC process.
>
> For rework we have tried to go "backwards" to Sn63 to reduce max temp. The
> results were better. Customer did not want to go throiugh the rel testing
> reqts of a bismuth-based alloy.
>
> Any thoughts on using a vapor phase reflow instead?
>
> BWET
>
> On Mon, Jan 23, 2017 at 1:29 PM, David Hillman <david.hillman@
> rockwellcollins.com> wrote:
>
>> Hi Bob - I have done process compatibility testing with the TI OMAP BGA
>> and the use of a inert atmosphere has no impact on the warpage
>> characteristics of the package (been there, done that, have the Tshirt).
>> Are you using a tin/lead soldering process or a lead-free soldering
>> process? POP technology was "born" in the lead-free era and as such, that
>> package isn't a fan of a tin/lead soldering profile.
>>
>> Dave Hillman
>> Rockwell Collins
>> [log in to unmask]
>>
>> On Mon, Jan 23, 2017 at 11:29 AM, Bob Wettermann <[log in to unmask]>
>> wrote:
>>
>>> Dear Technetters:
>>>
>>>
>>>
>>> We have a Class 3 customer with very complex, high density placements
>>> (think cell phone for the military). This board is laden w/0201s, 0.4mm
>>> pitch BGAs, shields, mirrored BGAs and the TI Omap POP (0.4/0.5mm pitch).
>>>
>>>
>>> The problems in this board assembly for some time have been isolated to
>>> this OMAP part.  We have lots of shorts and opens (randomly-spaced) as
>>> confirmed by electrical testing, dye and pry and cross sectioning. The
>>> Omap
>>> has been shown to warp 5-7 mils depending on the reflow profile.( It is a
>>> no clean SAC305 process). We have profiled the reflow process by
>>> embedding
>>> TCs in the corners of the balls of the device (ball interface with the
>>> board where all of the problems are) , the die,  neighboring components
>>> etc. We dialed in the profile as low of a temp as possible.
>>>
>>>
>>> We are running several DOEs to come up with a placement/rework process.
>>>
>>> As part of the investigation the client is fixated on nitrogen reflow
>>> being
>>> part of the solution to these warped BGAs. Nitrogen reflow IMHO is the
>>> solution for joint aesthetics, wetting issues and enhanced reliability of
>>> the interconnection.
>>>
>>>
>>> ? Does anyone have experience with hot air reflow using nitrogen where
>>> its
>>> addition helped to mitigate warpage issues?
>>>
>>>
>>> Thanks!
>>>
>>>
>>> --
>>> Bob Wettermann
>>> BEST Inc
>>>
>>
>>
>
>
> --
> Bob Wettermann
> BEST Inc
> [log in to unmask]
> Cell: 847-767-5745 <(847)%20767-5745>
>