[stephengillie]

What Coin has managed to do in such a thin package is really impressive. It’s a shame they weren’t able to do it more reliably.

It's a really cool idea. I actually wonder what the technological hurdle was that held them back - mechanical (reliably magnetizing the coils, easy-to-break components due to narrow size), software (programming issues), or QA (reliable SoCs, reliable builds, reliable solders)?

[pjc50]

I suspect flexing the PCB caused the usual problems of hairline cracks in solder joints, resulting in intermittent faults.

[thaumaturgy]

If that's true, I wonder if something like a paper circuit would work? e.g., http://www.instructables.com/id/Paperduino-20-with-Circuit-S...

[pjc50]

Flexible substrates are not a problem - the industrial solution is polyimide (Kapton) or just really thin FR4. The problem is inflexible components. As soon as you bend a curved surface attached to a small flat rectangle (IC), it pulls at the joins.

You might get better results with bare die+wirebonding, then encapsulating with slightly flexible epoxy. That would allow the bondwires to flex and take up the bending. Doesn't help with the discrete components or the battery.

[jaboutboul]

It would have been nice if they shared any of that info. Maybe more of us would be more sympathetic.

[ngoel36]

Very often, the merchant would just assume I was using an Amex e.g. Amex Black....even though the display read VISA. This, of course, caused a decline...not worth the trouble to argue.