looking for Qi charging receiver coil with TINY converter PCB/board...

Thread Starter

radiance32

Joined Mar 10, 2021
11
Hi Everybody!,

I would like to add inductive wireless charging (Qi standard) to a mobile device.
Unfortunately, the device has an aluminium back, so it won't be possible to use a charging coil on the back.

However, on the front of the device, there is a rather large IPS colour screen made of glass and plastic layers behind it that's only about 0.9 millimetres thick,
so I was thinking of making it so the receiver coil is behind the IPS screen.
The user will have to lay down the device with the front screen on the Qi charging pad, but this is the only way to achieve it.

I have 2 questions:

1. I've already added several things to the device and space is getting very, very limited. There are hundreds of Qi charging receiver coils available on sites like Alibaba etc,
at really cheap prices, but only a few of them have them little circuit board attached to them which converts the signal coming from the coil into 5V DC,
which I solder onto my battery charger mini PCB's 5V DC input (it currently uses a USB Type-C input) that I added to the device.
The problem is space, I've only a tiny amount of space available for the board that creates the 5V DC from the receiver coil.

Does anyone know of a good, thin Qi-compatible receiver coil (max 6cm x 4.2cm and as thin as possible), which comes with the converter board, and the board PCB should be tiny,
and with tiny I mean it should be equal to or smaller than 2cm x 1.5cm, and again, as thin as possible
(eg just a thin PCB with some tiny SMD ICs on it and pads where I can solder my wires on) If you do, please let me know which one and maybe a link to the part(s) information or eBay/element14/Alibaba/etc... sale page)

2. Does anyone think that the magnetic field created by the charger coil in the pad, going through the LCD panel, into the receiver coil which will be stuck on the back of the LCD panel is ok? Would it be in any possible for a setup like this to damage the LCD screen, or, over time cause it to get damaged or fade or degrade in any way?
Since the device will be switched off and not be used while it's lying face-down on the Qi charging pad, it doesn't matter what it does should the LCD be affected in any way while in use, as it won't be in use and switched off during the wireless charging process...

Please reply with simple responses as I've very limited electronics experience, and only really the basics and moderate soldering skills and equipment for everything except complex SMD soldering...

Thank you for your input! I really appreciate anyone here taking the time to read my message and maybe replying with some useful information... :)

Cheers!,
Terrence
 

Thread Starter

radiance32

Joined Mar 10, 2021
11
The only thing inductive charging produces that could affect the LCD is heat. How much? I don’t know.
Hi Yaakov,

Thanks a lot for taking the time to respond...
Do you think the actual induction power transfer with a magnetic field is going to warm up an LCD panel ?
(which is made of glass/plastics films etc...)

I know that when i charge my samsung S8 on a Qi charging pad, the back of the phone becomes warm,
but I'm not sure if it's due to the battery warming up from fast-charging,
or if it's due to the inductive charging coil heatingup (or a combination of both)...

I guess i'll have to give it a try on a unit with a poor LCD panel in it and see if it affects the panel...

Thanks for your time,
Terrence
 

Yaakov

Joined Jan 27, 2019
2,442
Most of the heat is from joule heating in the antennas. It can produce a lot. Special thermal design is needed to prevent it from damaging the phones and batteries long term.
 
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