look like your real world situation is exceeding ipc class 3... you  
got discoutinueity fault without stress test... you either redesign  
or write a better contract and/or better vendor qual to cover your  
own requirement... (space is different animal compare to the class  
3... class 3 is not space grade... at least not equivalent according  
to my knowledge... ).
On Oct 18, 2017, at 8:06 PM, Zilber Gil wrote:

> Thanks,
> Vendor sees it on HATS coupon, after the test. No discontinuity was  
> observed. He did cross section, and found that the pad lifting  
> comply to IPC 6012 class 3, as we requested. No pad lifting  
> observed before the stress. Thus, he sends us the boards.
> No changing in the process or material on the vendor side.
> Regards,
> Gil
>
>
>
> נשלח ממכשיר הSamsung שלי
>
>
> -------- הודעה מקורית --------
> מאת: Yuan-chia Joyce Koo <[log in to unmask]>
> תאריך: 18.10.2017 17:38 (GMT+02:00)
> אל: TechNet E-Mail Forum <[log in to unmask]>, Zilber Gil  
> <[log in to unmask]>
> נושא: Re: [TN] Pad lifting or lifted land
>
> you didn't see that from your vendor qualification unit?  does
> thermal stress is part of vendor qual?  does your contract said
> comply to ipc and equivalent to qual unit (equivalent or better)?
> did you change material/process? (CTE of filler material)... do you
> have sample saved from your qual  batch as witness sample, so you can
> go back to your vendor?  (normally qual unit add 2x reflow cycle, for
> example: top 2x, bottom 1x plus rework 1x - 4x +2 for qual... if you
> don't see any issue on qual unit, you go for production... that
> including thermal shock 10x check for discontinueity... fully
> populated unit).
> 90% of pad lift is major flaw, unless you did something strange, that
> not covered  in initial  qual (or your vendor is really crappy...
> good one will work with you and find out what hack is gone  wrong and
> make sure  no other customer see the same  fault).
> jk
> On Oct 18, 2017, at 10:22 AM, Zilber Gil wrote:
>
> > Fellow TechNetters:
> >
> > I have a problem of lifted land (via`s pad) after reflow. More the
> > 90% of the pads show it on both sides of the PCB (Vias are filled
> > and cap plating).
> > According to IPC lifted land after thermal stress is allowed.
> > In many cases, a conductor is connected to these pads and in this
> > case, the reliability of the connected area to the lifted pad is
> > probably very poor (most of the PCBS worked after the assembly, but
> > one show discontinuity. Many vias are under BGAs connected as a dog
> > bone to the BGA pads).
> > I contacted the manufacturer and he told me that the PCBs are ok
> > according to IPC thus they will not compensate us.
> >
> >
> > Now I have a few questions:
> > 1. IPC did not mention any conductor connected to these pads, why?
> > What about reliability issues in this case (obviously poor?)?
> > 2. Do I have any case against the manufacturer?
> > 3. At IPC 6012 and Mil-prf-55110 lifted land refer to the pad of
> > the vias, but it is not verbally written. It is showed on the
> > pictures (at the MIL). Thus, one can interpret that lifted land,
> > i.e. component pad, can be lifted from the board and it is
> > acceptable...?? (imagine a BGA "jumping" up and down during
> > vibration... :)
> > 4. After that issue, I am going to change our spec and not allowed
> > any lifted land (before or after thermal stress).
> >
> > Thank you for your inputs,
> >
> > Gil Zilber
> > Elta Systems Ltd.
> > The information contained in this communication is proprietary to
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> > confidential or privileged information, and is intended only for
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> > intended addressee, please be aware that any use, disclosure,
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>
> The information contained in this communication is proprietary to  
> Israel Aerospace Industries Ltd. and/or third parties, may contain  
> confidential or privileged information, and is intended only for  
> the use of the intended addressee thereof. If you are not the  
> intended addressee, please be aware that any use, disclosure,  
> distribution and/or copying of this communication is strictly  
> prohibited. If you receive this communication in error, please  
> notify the sender immediately and delete it from your computer.
>