Bumpgate: Difference between revisions

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These manufacturers had engineered GPUs that electrically connected the silicon chip (die) to the substrate (the "green square part") using high-lead solder bumps. High-lead solder bumps were chosen in order to fit the power delivery specifications that these GPUs needed.<ref>{{Cite web |last=Williams |first=Rob |date=29 Sep 2008 |title=NVIDIA at a Disadvantage Due to their Choice of Solder? |url=https://techgage.com/news/nvidia_at_a_disadvantage_due_to_their_choice_of_solder/ |url-status=live |access-date=1 Jun 2025 |website=Techgage}}</ref> To give these solder bumps more strength (especially when operating at high temperatures), it's standard to use an epoxy with silica filler known as underfill. Underfill needs to fit certain specifications, depending on how hot the processor it's used on is expected to get. If it's too hard, the underfill will crack the die. If it's too soft, the bumps will crack because the underfill isn't supportive enough. It also needs to still fit within the right specifications at both high and low temperatures.

In 2006, IBM and Amkor published a study that explained that use of a low Tg underfill was not acceptable with high-lead solder bumps, and high Tg would be necessary to avoid defects.<ref>{{Cite journal |last=Ray |first=S. |last2=Kiyono |first2=S. |last3=Waite |first3=K. |last4=Nicholls |first4=L. |date=2006 |title=Qualification of low-K 90nm Technology Die with Pb-free Bumps on

In 2006, IBM and Amkor published a study that explained that use of a low Tg underfill was not acceptable with high-lead solder bumps, and high Tg would be necessary to avoid defects.<ref>{{Cite journal |last=Ray |first=S. |last2=Kiyono |first2=S. |last3=Waite |first3=K. |last4=Nicholls |first4=L. |date=2006 |title=Qualification of low-K 90nm Technology Die with Pb-free Bumps on a Build-up Laminate Package (PBGA) with Pb-free Assembly Processes |journal=56th Electronic Components and Technology Conference |pages=139-144 |via=IEEE}}</ref> Therefore, because Nvidia and ATI chose to use high-lead solder bumps, they needed a high Tg underfill. However, this study was not out at the time that GPUs from 2005 were made, and the companies ended up using low Tg underfill in these processors.

a Build-up Laminate Package (PBGA) with Pb-free Assembly Processes |journal=56th Electronic Components and Technology Conference |pages=139-144 |via=IEEE}}</ref> Therefore, because Nvidia and ATI chose to use high-lead solder bumps, they needed a high Tg underfill. However, this study was not out at the time that GPUs from 2005 were made, and the companies ended up using low Tg underfill in these processors.

This low Tg underfill would become too soft at high, but normal operating temperatures for these GPUs. When the processor went through normal thermal changes, the solder bumps would soften under heat and harden as they cooled.<ref name=":0">{{Cite web |last=Demerjian |first=Charlie |date=1 Sep 2008 |title=Why Nvidia's chips are defective |url=http://www.theinquirer.net/inquirer/news/1004378/why-nvidia-chips-defective |url-status=dead |archive-url=https://web.archive.org/web/20090520152257/http://www.theinquirer.net/inquirer/news/1004378/why-nvidia-chips-defective |archive-date=20 May 2009 |access-date=1 Jun 2025 |website=The Inquirer}}</ref> This would happen over and over again until they cracked under the thermal stress. When enough solder bumps cracked, it would cause a failure in the unit, hence the term "Bumpgate".

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 These manufacturers had engineered GPUs that electrically connected the silicon chip (die) to the substrate (the "green square part") using high-lead solder bumps. High-lead solder bumps were chosen in order to fit the power delivery specifications that these GPUs needed.<ref>{{Cite web |last=Williams |first=Rob |date=29 Sep 2008 |title=NVIDIA at a Disadvantage Due to their Choice of Solder? |url=https://techgage.com/news/nvidia_at_a_disadvantage_due_to_their_choice_of_solder/ |url-status=live |access-date=1 Jun 2025 |website=Techgage}}</ref> To give these solder bumps more strength (especially when operating at high temperatures), it's standard to use an epoxy with silica filler known as underfill. Underfill needs to fit certain specifications, depending on how hot the processor it's used on is expected to get. If it's too hard, the underfill will crack the die. If it's too soft, the bumps will crack because the underfill isn't supportive enough. It also needs to still fit within the right specifications at both high and low temperatures.
-In 2006, IBM and Amkor published a study that explained that use of a low T<sub>g</sub> underfill was not acceptable with high-lead solder bumps, and high T<sub>g</sub> would be necessary to avoid defects.<ref>{{Cite journal |last=Ray |first=S. |last2=Kiyono |first2=S. |last3=Waite |first3=K. |last4=Nicholls |first4=L. |date=2006 |title=Qualification of low-K 90nm Technology Die with Pb-free Bumps on
+In 2006, IBM and Amkor published a study that explained that use of a low T<sub>g</sub> underfill was not acceptable with high-lead solder bumps, and high T<sub>g</sub> would be necessary to avoid defects.<ref>{{Cite journal |last=Ray |first=S. |last2=Kiyono |first2=S. |last3=Waite |first3=K. |last4=Nicholls |first4=L. |date=2006 |title=Qualification of low-K 90nm Technology Die with Pb-free Bumps on a Build-up Laminate Package (PBGA) with Pb-free Assembly Processes |journal=56th Electronic Components and Technology Conference |pages=139-144 |via=IEEE}}</ref> Therefore, because Nvidia and ATI chose to use high-lead solder bumps, they needed a high T<sub>g</sub> underfill. However, this study was not out at the time that GPUs from 2005 were made, and the companies ended up using low T<sub>g</sub> underfill in these processors.
-a Build-up Laminate Package (PBGA) with Pb-free Assembly Processes |journal=56th Electronic Components and Technology Conference |pages=139-144 |via=IEEE}}</ref> Therefore, because Nvidia and ATI chose to use high-lead solder bumps, they needed a high T<sub>g</sub> underfill. However, this study was not out at the time that GPUs from 2005 were made, and the companies ended up using low T<sub>g</sub> underfill in these processors.
 This low T<sub>g</sub> underfill would become too soft at high, but normal operating temperatures for these GPUs. When the processor went through normal thermal changes, the solder bumps would soften under heat and harden as they cooled.<ref name=":0">{{Cite web |last=Demerjian |first=Charlie |date=1 Sep 2008 |title=Why Nvidia's chips are defective |url=http://www.theinquirer.net/inquirer/news/1004378/why-nvidia-chips-defective |url-status=dead |archive-url=https://web.archive.org/web/20090520152257/http://www.theinquirer.net/inquirer/news/1004378/why-nvidia-chips-defective |archive-date=20 May 2009 |access-date=1 Jun 2025 |website=The Inquirer}}</ref> This would happen over and over again until they cracked under the thermal stress. When enough solder bumps cracked, it would cause a failure in the unit, hence the term "Bumpgate".