Thanks Joyce,

Good points. What temperature is necessary to create this kind of damage?
Can the die hit this temperature if the heat evacuation is not perfect?

Also, the discoloration really goes along all metallized features and is not localized. Something affected the whole surface to the same extent.

Dean,
EDX did not reveal any contaminant so I wonder if there could be anything else.

Best regards,

Ioan

-----Message d'origine-----
De : Yuan-chia Joyce Koo [mailto:[log in to unmask]] 
Envoyé : September 12, 2017 10:46 AM
À : TechNet E-Mail Forum; Ioan Tempea
Objet : Re: [TN] Die discoloration

over heating?  what is your die attach?  any voiding % more than 25% in any of quadroon?  only one unit or many?  does the part datasheet required heat sink at backplane with multiple stack vias?  any of those vias are good large enough? (datasheet spec for thermal plus 20-30% if your PWB FAB house via recessed to prevent contact... any via outgas resulted die attach problem?)... my guess.
On Sep 12, 2017, at 9:25 AM, Ioan Tempea wrote:

> Dear Technos,
>
> I know many of you, not only Steve Creswick and Wayne Thayer, have 
> experience in microelectronics, so I dare poking you with this 
> situation I'm having.
>
> There's this Ka band MMIC die that was properly working in the 
> beginning, only to see its performance degrading over time. Visual 
> inspection revealed a strange discoloration running along all the 
> metallized features and the glassivation is cracked here and there.
>
> Please see image graciously placed by Stevie G on his website 
> http://stevezeva.homestead.com/MMIC_Die.jpg
>
> What during the assembly process could cause this kind of visual 
> aspect?
>
> Can this be a cause of the degrading performance?
>
> Is it possible the die was like this from manufacturing (improper 
> pre-glassivation cleaning or something)?
>
> Any other impressions?
>
> Thanks,
>
> Ioan Tempea