FP3(+) backside angular stripes: Are they important? If yes, how to repair/replace?

[kolAflash]

What are the angular stripe patterns on the backside of the FP3(+) for?
You can see them when you remove the backside cover.
Are those maybe antennas?

Some parts of those stripes are worn off on my FP3.
Can this cause technical problems?
If yes, if there a way to fix this or a replacement part?
Maybe a special coating / lacquer with which they can be repainted?

[rkbwde]

Could be antennas or a ground conductor plain.

Do have problems with low signal strength in phone or WiFi networks ? Or blue tooth ? Or NFC ?

[AnotherElk]

Here’s something interesting …

Fixing Weak signal fairphone 3

Just to share an experience on fairphone 3, that had with time weaker and weaker reception. Ended up obliged to leave phone outside even in major cities, remembered me early mobile phone network… I found out the pattern of the antenna at the back (upper right) was damaged and cut in several places. I managed to fixed it using a conductive paint, not sure how long time it will last but I am now back with normal reception. Purist will argue i did not probably did not matched excalty the impedan…

[Incanus]

@kolAflash

What are the angular stripe patterns on the backside of the FP3(+) for?

Please check:

Fixing Weak signal fairphone 3

Just to share an experience on fairphone 3, that had with time weaker and weaker reception. Ended up obliged to leave phone outside even in major cities, remembered me early mobile phone network… I found out the pattern of the antenna at the back (upper right) was damaged and cut in several places. I managed to fixed it using a conductive paint, not sure how long time it will last but I am now back with normal reception. Purist will argue i did not probably did not matched excalty the impedan…

[rkbwde]

I asked a friend who is an expert. He thinks that those are combined antennas for phone, WiFi and bluetooth. However, a repair with conductive paint will probably not work as you need to match layout and impedance exactly for the antennas to work properly. On the other hand, if it doesn’t work you don’t have anything to lose

So if you experience problems you may need a new module - which shouldn’t be a problem with a Fairphone

[kolAflash]

@El_Grinch

I found out the pattern of the antenna at the back (upper right) was damaged and cut in several places. I managed to fixed it using a conductive paint, not sure how long time it will last but I am now back with normal reception.

@El_Grinch
Could you share which conductive paint that was and where to buy it? Thanks

 

@rkbwde

Do have problems with low signal strength in phone or WiFi networks ? Or blue tooth ? Or NFC ?

I currently use that FP3+ only for ROM image testing. So I’ve got no SIM card in that phone and I didn’t use Bluetooth or NFC. But WLAN / WiFi seems to work fine.

 

@rkbwde

[…] So if you experience problems you may need a new module - which shouldn’t be a problem with a Fairphone

Unfortunately I couldn’t find that replacement part in the official store.
https://shop.fairphone.com/shop/category/spare-parts-4?category=4&filters=35-37
But I’d guess one can be found at eBay.

[El_Grinch]

Blockquote Could you share which conductive paint that was and where to buy it? Thanks

Hate to say it was on amazon, called liquiwire, but there are a lot of different other products. If you are in big town, most serious electronic shop should have similar product to fixed damaged PCB.
It is like ink, so i had to put several thin layer and let it dry in between. Be very careful not to short circuit existing strip, respecting as much as you can original pattern, and remove battery while doing it in case!
I saw it exist also other silver base paste.
Did it a week ago, so far so good, but not sure how it will evolve with time.
If you are in france DM me, i got 50 ml, enough to paint 100s of FPs and probably wont use it anymore.

[kolAflash]

@El_Grinch Thanks for the hint!
Tried it and seems to work well.

Liquiwire 50ml Electrical Conductive Paint for PCB and Electrical Circuit
https://www.amazon.de/dp/B07XBGZRV7

I applied it with a small steel wire instead of a brush.

I measured the resistance of the dried paint with a Multimeter. It seems to be about 20 to 200 times higher then the existing metal stripes. I hope that’s not too much.
(measured 1 Ohm for the original metal stripes and 20 to 200 Ohm for the conducting paint)