A few weeks ago many users of the new AMD RX 7900 XT and 7900 XTX reported temperatures on their graphics above 100 ºC. Quickly, AMD came out to say that this was normal and that there was not the slightest problem. Although, most processors and graphics cards protect themselves by “turning off” before reaching 100 ºC, and the reason is their construction.
The processors and GPU of the graphics card are made of silicon, most of which melts at more than 1400ºC . Something that not everyone knows is that other materials are added in current manufacturing processes. The reason for the limit of 100 ºC is really in another point that you can’t even imagine.
Where does the 100 ºC limit come from in processors and graphics?
Well, knowing that silicon melts at 1400 ºC, one might think: ” why do processors “turn off” when they reach 100 ºC? ” Well, the reason, mainly, is in the union that exists between the DIE of the processor or graphics card and PCB. Both elements are created separately and joined by tin.
It is precisely the tin that limits the operating temperature of the processors. The approximate melting temperature of tin is 230ºC, although it may vary depending on the composition of the alloy. Pure tin is not used in the solder, different combinations of materials are used.
We have gone from more than 1400 ºC to approximately 230 ºC, and the limit of 100 ºC is beginning to make more sense. There is still a large margin, one would think that manufacturers could modify the “shutdown” of the chip for its protection at 150 ºC, but it is not recommended at all.
We don’t care that tin melts at 230 ºC, the problem is in the stress of the soldering. When a material heats up it expands and when it cools down it contracts. High as “simple” as this generates strong degradation in tin. So much so that many times a graphics card that doesn’t work , after being subjected to reballing , works perfectly.
Reballing? What’s that?
This is normally only done on graphics cards, removing the GPU from the graphics PCB . It is not done in processors because it is much more complex and because the tin solder is very small.
Put simply, reballing involves heating the GPU until the tin liquefies and can be removed. Then, all this old tin that did not allow conductivity is removed and replaced with new tin. It heats up again and the weld is now perfect.
This process has many problems and difficulties . The first one requires a very specific and expensive machinery . In addition, it requires significant technical knowledge , so as not to break the graphics or damage the GPU due to excessive heat. To top it off, good ventilation is required, as tin is often combined with lead , which is highly toxic.
A bad practice that is used and should not be , is to do it in a home oven . There are several reasons, but the most important is that a part of the tin and lead gasify and stick to the walls of the furnace. Both materials are highly toxic and even if you clean well, these metals can pass into food and when ingested, we would become seriously ill.
Currently, it is what it is
Most likely you think that tin should be replaced by another material. The truth is that there is no better material for the following reasons:
- Tin is very cheap and easy to produce.
- Offers good stability at elevated temperatures (over 50º C)
- It can be shaped quite easily
Unfortunately, we currently do not have an interesting alternative to this material. Other materials are being investigated and some are used, especially for hardware that will be subjected to high thermal stress. But commercially, tin, due to its properties, is the best and most economical solution.