With the Lumia 950 XL, Microsoft introduced a water-cooled smartphone to its lineup. While the idea of a water cooled smartphone isn’t new, the 950 XL will be the
first phone to bring this implementation to the mainstream market. However the first phone which came with water cooling tech was NEC’s Medias X N-06E.
Why Smartphone Needs Cooling?
Let’s start by stating the obvious- every smartphone runs the way it does by deploying a processor. These processors are the units responsible for the continuous crunching of bits and, ultimately, giving you the experience you want. This work is done by microscopic transistors that switch states – a process that generates heat. Multiplied to scale, considering how many of these transistors exist in a modern CPU(billions), and you have your question answered. Cooling a CPU is critical to its performance and for a sustained use.
How To Cool A Smartphone?
Throttling ( Performance Suffer )
Let us illustrate with an example- say your phone’s processor runs at 1.0 GHz. This is the phone’s upper maximum, a state where the highest amount of performance can be observed, however it is also the state where the highest amount of heat is generated. To resolve this problem, your phone’s CPU dynamically switches between lower power states when the workload is low(say, 200MHz when you simply type on a keyboard). The problem arises when you undertake a CPU-intesive task such as playing a game.
Here, your CPU needs to run at its highest clock speed(1.0 GHz) to provide you with a seamless experience. However, when the heat generated by the processor, performing at its maximum throughput as it is, reaches a tipping point(hard coded by the CPU manufacturer) the CPU needs to forcefully ‘throttle down’ disregarding a seamless experience. Lo and behold, your experience with a once-seamless game turns into a laggy mess; the tradeoff being that your CPU saved itself from frying itself off the SoC.
Air cooling is implemented by almost every smartphone today. It is the technique generally used to prevent the CPU from overheating and throttling. Essentially, a metal plate is placed in contact with the surface of the CPU. This metal is chosen based on its properties of ease of heat absorption. This metal is then further connected to the body of your smartphone. The heat passes through the metal plate and to the build of your phone and, finally, dissipates. This is the reason your phone gets hot when you put it through a strenuous work load.
While cooling a phone through dissipation via air cooling has proved adequate for quite a long while and probably will for some time to come, some manufacturers are not ready to settle with the limitations air cooling and the subsequent throttling puts on the performance of their CPUs. The solution to a prolonged high-performance state, then, is water/liquid cooling. Water cooling is an instance of liquid cooling so we will concentrate our narrative on liquid from hereon. Liquid cooling typically requires a liquid that has low boiling points and high condensation temperatures to be leveraged.
Simply put, the liquid should be able to absorb the CPU’s heat and dissipate it as fast as it possibly can. As for how it works, the liquid is basically made to absorb the CPU’s heat(without actually coming in contact with it since liquids and electronics are have always been disagreeable with one another) via metallic plates and tubes. The liquid, now turned hot, is then passed away from the CPU to eventually make the body of the smartphone absorb the heat and let it out of the system. Undoubtedly, this keeps the CPU much cooler at the expense of adding additional hardware.
Does water cooling on a smartphone make sense?
Coming back to the reason why the existence of this article was validated- the 950 XL. It houses a water cooled Snapdragon 810 that dissipates heat through its magnesium body. ‘Why?’, you might ask, and you’d be right in your skepticism since phones such as the One Plus Two and the Nexus 6P house the same processor with the simpler air-cooled build.
Water Resistant Vs Water Cooling ?
IPX68 Certification is a one way to make a phone which can still work even when you submerge it inside water. We have seen this happening in most of the Sony flagship xperia series phones, but would you literally dip your phone in water to cool it down. Most of the people would say no to this, they would rather leave the phone idle for cooling it down. Water cooling of smartphones seems to be a much intelligent tech which makes sure that phone does not heat up at the same time.
Why Liquid Cooling in Lumia 950 XL?
The answer lies in two possibilities – the first, Microsoft chose to implement water cooling on its 950 XL since it wanted the throttling of the Snapdragon 810 to be delayed as much as possible; allowing it to perform at its fullest for maximum amount of time. The second might be a purely marketing standpoint.
So does this mean we are going to see more phones with water cooled CPUs in the future? Probably not; because as cool as it can sound (pun unintended) to have water cooling on your phone, with devices getting thinner and lighter and other requirements such as cameras and battery life being a prime issue(causing vendors to invest more in those segments rather than in the additional requirements to implement water cooling), reducing CPU-caused heat needs to be a function of chip design and materials used in heat-dissipation. Let us know if you would rather prefer a water-cooled smartphone to a traditional, air-cooled one in the comments bellow.