Sony has an outstanding debt with users. He refrigeration system that you have implemented on both PS4 and PS4 Pro It is very noisy at times of maximum workload. In fact, it becomes annoying. The latest PS4 Pro reviews have toned down this problem slightly and lowered the noise level by a few decibels, but not enough at all to solve this handicap in a fully satisfactory way.
Many users were looking forward to having more information about the PS5’s cooling system to be able to intuit if Sony had managed to solve this problem in its new generation console. The video game forums are full of comments from fans who have expressed their concern, and fortunately, Sony has responded. And it is that a few hours ago posted a video in which one of the heads of the mechanical engineering department completely disassembles the console and reveals how is your cooling system.
There is no doubt that we cannot be sure whether this solution is really effective and whether or not it is silent until we have the console at home, but the information that Sony has revealed confirms that they have taken great care in the design of the PS5’s cooling. On the other hand, it is what he played.
Huge 120 x 45mm turbine-type fan and gigantic copper-rich heatsink look really good, but the most striking feature of this cooling system is the liquid metal which acts as an interface between the core of the SoC and the base of the heatsink. It is very likely that this component is largely responsible for the cooling capacity of this console, and for this reason it is worth getting to know it a little better.
TIM: what is it and why is it so important
The acronym TIM comes from the name in English Thermal Interface Material, and describe what material is used as thermal interface between a chip and the heatsink who is responsible for refrigerating it. If we stick to microprocessors and graphics processors, which are the chips that tend to dissipate the most energy in the form of heat, the TIM acts as an interface between the encapsulation that covers the CPU core and the base of the heatsink.
The mechanism that explains how the transfer of thermal energy takes place between two solid elements is known as conduction, and its efficiency is greater when the contact surface between the two objects is maximum
Manufacturers of semiconductors and heatsinks tend to take great care so that the contact surface between these components is homogeneous and is as polished as possible because it is crucial to maximize it to optimize energy transfer in the form of heat between them. However, no matter how well resolved the metal is, it has small imperfections that are very difficult to correct even if they are machined very precisely.
The mechanism that explains how the transfer of thermal energy takes place between two solid elements it is known as conduction, and its efficiency is greater when the contact surface between the two objects is maximum. The problem is that if these two surfaces are not completely homogeneous, which in this context they never are, those small imperfections end up being occupied by tiny air pockets, which is a poor conductor of thermal energy.
This deficiency, precisely, justifies the existence of the TIM, which in practice is a thermal putty or paste that is placed between the surfaces of the CPU or GPU housing and the heatsink. In this way, the thermal paste forms a thin film of material that fills in the imperfections of the metallic surfaces in contact and favors the conduction of thermal energy, which, precisely, is what we are looking for.
TIM is usually a thermal paste that is placed between the surfaces of the CPU or GPU housing and the heatsink.
Each thermal paste manufacturer has its own recipe, so not all putties have the exact same composition. Some use aluminum oxide; others are boron nitride, zinc oxide or aluminum nitride, and a few, the more sophisticated, contain silver particles in suspension. The composition of a thermal paste is important because conditions its thermal conductivity index, a parameter that measures the ability to transport energy in the form of heat that a material has.
The heat conductivity of metals is significantly higher than that of non-metallic materials, such as thermoplastics or wood, which is why it is so important to introduce metallic particles into thermal paste. In this way we are able to increase the energy transport capacity in the form of heat of the compound, but we also run the risk of increase its electrical conductivity, and this could give us problems if the putty comes into contact with any electrical or electronic component of our computer.
Liquid metal is a good choice, but difficult to handle
As we have just seen, the thermal conductivity index of thermal pastes is higher than that of air, which is a good thermal insulator. Even so, the heat conductivity of these putties is much lower than that of metals, so the ideal TIM would be one with a heat conductivity coefficient as close as possible to that of metals. In that case, why not use a liquid metal as the interface between the CPU / GPU package and the heatsink? In this way we maximize the contact area between metal surfaces, evacuate the air and have high heat transfer capacity.
Using a liquid metal alloy like TIM is a very attractive strategy due to its ability to conduct heat, but it poses a challenge: it is crucial to prevent this component, which also has the ability to conduct electricity, from coming into contact with other elements. of the team. Liquid metal compounds used in electronic applications with the purpose of promoting the transport of thermal energy usually resort to an alloy of gallium, indium and tin known as galinstano.
The thermal conductivity index of liquid metal can be up to 80 times higher than that of a conventional thermal paste
Its thermal conductivity index can be up to 80 times higher than that of a conventional thermal paste, but, in addition to how difficult it is to handle to prevent it from coming into contact with other components, it has a disadvantage that we cannot ignore: gallium greatly weakens aluminum due to the fact that it manages to infiltrate between the crystals that compose it and reduces the force with which they are linked to each other. For this reason, the ideal is that liquid metal alloys that use gallium do not coexist with aluminum surfaces. Copper is a much better option.
The choice of gallium is not accidental. And it is that the melting point of this metal is 29.7 ºC, so it remains in a liquid state at a relatively low temperature. The melting points of indium and tin are higher, but by acting on the proportion of these elements it is possible to play with the melting point of the liquid metal compound. Sony ensures that its engineers they have invested two years in the design of the cooling system of PlayStation 5, which reflects that they are aware that this console must perform better in this area than its predecessor.
We do not know the composition of the liquid metal that acts as TIM in PS5, but it is likely similar to what we just described, and therefore contains gallium. In any case, there is no doubt that an important part of the effort of the engineers of this company has gone to the design of the enclosure, which is responsible for preserve tightness when the metal alloy melts. As we have seen, it is essential that the liquid metal does not come into contact with other components. The following image comes from Sony’s patent which describes the design of the enclosure that confines the liquid metal alloy.
The number 31 of the scheme indicates the location of the metal alloy, and the 33 the presence of the elements that are responsible for sealing and maintaining the tightness of the enclosure when the console is turned on, the metal heats up and reaches its point of fusion. The components identified with the number 16 are capacitors, and the element that has the number 15 is an insulating material that prevents these capacitors from coming into contact with the metal in a liquid state. In the following diagram I have marked in red the enclosure through which metal alloy is distributed when it reaches its melting point.
In this patent Sony indicates that its design guarantees tightness even when the console is reoriented or subjected to vibrations, and this certainly must be the case because the PS5 can be positioned both vertically and horizontally. Also, an accidental bump when the console is in operation should not cause liquid metal to come into contact with other components of the machine. So far it seems that Sony has everything under control.
As I mentioned in the first paragraphs of this article, the cooling system that Sony has designed for PS5 on the wallpaper looks good. Further, liquid metal hardly degrades with state changes, so its useful life should be long. Even more than that of conventional thermal paste. In any case, we will put this cooling system to the test when this console falls into our hands.