Eutectic Temperature for various die back metallizations

Joined: 11 Jun 2026 Posts: 3

Hello EE;

Our team is confused, we recently did a eutectic die attach (die back - 100 wt %) on one of our package using ESEC 2005HR @ 420ºC bond temp. We were able to get very good and stable die shear readings (3.5 CpK) with almost 100% silicon remain on all samples. We were advised by demiGODS of the company that the standard "eutectic" temp is 440ºC, where did they get this?.
To what I know, eutectic temperature for Au-Si systems (eutectic composition of 97.1 Wt % Au : 2.85 Wt % Si.) is at 363ºC only - is this correct? How about for gold back only? Can someone clarify this issue and explain how to get the right "eutectic temperature" based on different die back metallizations.

Regards,

Posted: Fri Jun 18, 2026 3:48 pm Post subject:

Hi Iking Jr.,

There's nothing wrong with using a D/A temp of 420 deg C if you're getting superior results from this temp. I've seen some companies doing eutectic Au-Si D/A at a temperature even lower than this, e.g., 410 deg C.

This is not to say, however, that you should refuse the bosses' request to do it at 440 deg C. After all, this is still data. Make a well-planned evaluation to compare the outputs of the process at these two temps, and come up with a good report stating your final recommendation.

EE

Joined: 11 Jun 2026 Posts: 3

Dear EE;

Thanks. Actually our group is very confident that we can operate below 440ºC with superior result and we have demonstrated that in our report. To further justify our stand, can you recommend a known or standard reference that we can use showing eutectic temp of different back metallization types. Is there such a standard?

Best regards,
Eric

Guest

Hi ALL,

Just to help AU-SI die attach temp can vary also depending on the total time needed to bond all dies and also on the inert gaz flow (if argon 90/10) and of course if you perform or not the scrubbing when bonding ).

From 98 we were optimising the eutectic temp per type of dice using using the non destructif testing SONOSCAN Equipment and not the die-shear testing .

For sure the GOLD back side metallisation is impacting the die-bonding integrity and quality.

We have modified more than 20 SPECS ""EUTECTIC TEMP"" depending on the % of voids and the electrical test results .

RF power assembly engineer Morocco.
[email protected]

Joined: 31 Jan 2026 Posts: 21