This announcement gives people a strong reason to wait till the Dogwood batch to get improved cooling.
There was no mention of heat pipes in Birch in the announcement, so I presume that Purism has decided to scrap that idea and instead use a metal sheet that will connect directly to the metal frame to dissipate heat. That will be a lot cheaper than heat pipes, which I understand are quite expensive to implement, because they have to be customized to the phone, so they don’t really make much sense for low-volume production.
I assume what happened is that Purism realized that it needed better cooling, and then it started asking suppliers what it would cost and how long it would take. After hearing the cost and the time to implement heat pipes, it started searching for a cheaper solution. This means redesigning the board to move the i.MX8MQ to the other side, so there will be many changes.
The fact that a graphite sheet isn’t enough cooling shows how hard it is to use a processor like the i.MX8MQ that wasn’t designed for mobile phones. The kernel bugs that Purism is having to solve also show how hard it is to use a new SoC which doesn’t yet have good mainline Linux support.
All this work makes me appreciate just how hard it is to design a phone that is able to run on 100% free software. It would have been much easier for Purism to use a chip that already had good kernel support like Allwinner A64 or Rockchip RK3328.
The other question is whether it would have been better for Purism to announce immediately that it had found problems in its Aspen batch and leave people hanging as to what would happen next, or to wait until it figured out what it was going to do before making an formal announcement. If it had done the former, would people have freaked out even more than they did and would more people have canceled their orders?
Purism caused a lot of speculation when nobody received phones, but there also would have been a lot of speculation if Purism had made an announcement on Sept 24 that it had encountered severe problems and hadn’t decided what to do about it. Purism might also have thought that it could solve the problems within a month, so it could still ship Aspen on time.