We have a 5 zone oven.....and a BGA rework station (tried with some boards
with the OMAP missing and all other parts populated) w/multi zone bottom
heater.

BWET

On Mon, Jan 23, 2017 at 1:54 PM, David Hillman <
[log in to unmask]> wrote:

> 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 <
>> [log in to unmask]> 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>
>>
>
>


-- 
Bob Wettermann
BEST Inc
[log in to unmask]
Cell: 847-767-5745