Designing An iPad Cooling Case

A while back, I was referred to someone who had an issue with overheating iPads (the 3rd gen one). Due to the nature of his work (coaching/sports science), he often uses the iPad under the sun, which contributes a fair amount of heat to the iPad, and it was overheating to the extent that it would shut down. The shutting down was meant to be a safety feature to prevent it from blowing up, but this became a huge inconvenience for him. So the challenge for me was to come up with a solution to cool down the iPad so that he can continue using it under the sun.

RESEARCH

First I did a bit of research on the internet, and found that the new iPad (3rd gen) did have an issue with overheating. An article from Reuters even found that the iPad racked up temperatures of up to 47 deg Celsius after 45 minutes of running an intense action game. It didn’t bother most people (from what I read on the forums) because they will just stop using the iPad when it got too warm and let it cool down, or use it on the table instead of holding it with their hands. But for someone who needs to use the iPad as a sports training tool under the sun, it was a problem.

DESIGN RESEARCH

Next, I explored the possible options for cooling the iPad:

1. Cooling with water – People who overclock their PCs are usually the ones who would try using a water cooling system. You could build one on your own, or buy a system off the shelf. It will work for a PC, but an iPad? I am not too sure. I think one thing for sure is it will make the iPad way too bulky.
2. Using an ice pack – Anything that is zero degrees should cool things down. But, the thing is, it will also cause condensation. There will be water droplets everywhere, your hands gets slippery and oops, you drop the iPad on the ground. Not a good idea.
3. Heat sink – Heat sinks are only effective if there is complete contact between the hot surface and the heat sink; and typically that is achieved by applying heat sink compound or thermal paste between the surfaces. Also sticking a couple of heat sinks at the back of the iPad might make it less ergonomic to carry.
4. Cooling fans – Now this might work. All we need is somewhere to mount the fans, allow the air to move around the back of the iPad and carry the heat off the surface.

FEASIBILITY TEST

Out of the 4 options, I picked the cooling fans since it seemed the most feasible solution. My initial plan was to build a 3D model and run a CFD simulation to test out the concept. But when I started to draft something on SolidWorks, I ended up designing an iPad case which could house two 10mm fans and with channels for directing air across the back of an iPad. Then since I had access to 3D printing,  I decided to just build the prototype, get two 10mm fans and ran an actual test with the iPad. 

On one of the few sunny days in autumn, I borrowed a 3rd gen iPad and subjected it to some ‘heating’. I turned on the iPad, stuck a thermocouple on it’s back and left it under the sun. It was about 30 deg C that day. Once the thermocouple reading reached 45 deg C, I inserted the iPad into the prototype case and turned on the fans, while leaving it under direct sunlight. The good news was that the temperature dropped by 5 deg only after a minute or two with the fans on. But rate of cooling slowed down after that and it dropped to 34 deg C after 20 minutes. 34 deg C is still quite warm but since this is still under direct sunlight, and it was a 30 deg C day, I would say it was quite effective.

DESIGN IMPROVEMENTS

In my opinion, the concept worked. The design just needs a bit of tweaking. Firstly, I didn’t get the dimensions of the iPad right so the case didn’t really fit that well. Secondly, I picked the wrong fans – they were a little too big and they needed a 12V supply. Thirdly, the fans had to be switched on manually – it would be better if there was a temperature controlled switch.

So I got all those sorted out:

• Improved the case design. Even added a slot to mount a wide angle lens for the rear camera.
• Found smaller fans that only required 5V power supply.
• Also got some help with building a temperature sensor circuit that will switch on the fans when it gets too hot (it’s adjustable via a variable resistor).

NEXT PHASE?

Before I went ahead to build a second prototype, I decided to find out how much it would actually cost to 3D print it (The first prototype I got was given to me in kind). To my surprise, it would cost over $600. It would actually be a hundred dollars cheaper to have the case prototyped using CNC machining. On the other hand, all those electronic components plus the fans would only cost less than $20.

Well, if I was making a few thousand of those cases, I could just design moulds and get those parts extruded which would then bring down the cost of each iPad case. But how many people will actually need a cooling case for their iPad??

Also when I was working on this project (back in April), there was already the 4th gen iPad in the market, which was kind of an improvement. There were still complains of the iPad 4 is too warm, but I was thinking, it wouldn’t be long before Apple came up with a newer model that will totally solve the heat issue. Fast forward to today, out comes the iPad Air with a brand new processor! Apple has also stopped manufacturing the 3rd and 4th generation iPads. That’s probably because they realised they were inferior designs!

IN THE END

Although I didn’t get to mass produce these iPad cooling cases, it was overall a good experience. I realised that I would have to work faster if I wanted to make accessories for tablets or smartphones because a newer and better version is always coming out. Also, the cost of commercial 3D printing services is way too high. If I wanted to get 3 prototype cases built, I will be better off buying myself a 3D printer. The cost of thermoplastics for printing doesn’t seem too expensive. Might be cheaper than traditional ink cartridges!

Anyway, thanks for reading, and if you think this iPad cooling case is a good idea and you want to get one, let me know!