Connecting without a board mount

[shaun39]

Looking to apply an nRF52 chip in a wearable device... ideally without mounting it on a board.

Is that remotely feasible?

It would still be necessary to connect to 12 GPIO pins (alongside DC/DC for power supply). These connections would ideally be 0.1mm diameter cable, directly to the nRF52 chip. (This is a wearable application where the chip won't be collocated with the battery and sensor.)

How would you go about soldering or otherwise fixing 0.1 mm (or finer) cable to the pins on an nRF52 chip directly? Are there any examples of this being done?

[awneil]

shaun39 said:

Is that remotely feasible?

No.

But, surely, if you have space for a battery - it could go on a PCB there?

Some people are using flexi PCBs in such applications...

[shaun39]

Thank you awneil!

That would seem to settle the matter at a practical level (I'm curious whether anyone has seriously attempted this or if there's a very good reason not to try?).

Follow up question r.e. a flexi-PCB (seemingly the best solution here), where are the best places to design and purchase a flexi-PCB compatible with an nRF52 chip? And in the context of a prototype/ proof of concept (so just a few dozen PCBs initially)?

Are there any generic flexi-PCBs appropriate to use in a case such as this (only real requirement: breaking out GPIO pins).

[ketiljo]

I'm not aware of any modules with flexi PCB, pretty sure it doesn't exist. You either have to use a commercially available module or you have to design it yourself. 

[awneil]

Yes,  I was thinking of people doing chip-level design rather than modules. But there's no particular reason why you shouldn't put a module on a flex PCB.

I have worked with a company which was doing such a thing.

But not come across a flexi module.

Yet ...

[awneil]

shaun39 said:

if there's a very good reason not to try?)

Apart from the plain impracticality of doing it at all, I don't know how you'd manage the impedance control for the antenna connection.

Flexi PCB design is a specialist area, and doing it for RF would be a specialisation within that.