How to repair trace layer of keyboard?

Thread Starter

bypassrestrictions

Joined Jun 1, 2021
94
How to repair trace layer of keyboard?

I have a brand new keyboard, all of a sudden it developed problems few buttons not working, all the physical buttons are working fine and they going down and coming up. I've searched the net for how to repair it, many videos showed how to do it with multimeter and using conductive paint, I've repaired using those methods but still the problem persists.

It is a strange problem where sometimes some buttons and sometimes they don't work. I've checked the alignment of the bubble layer and trace layer and they are aligned, I've checked interface to the PCB and it is fine too, I've checked the trace layer again with multimeter and it is fine too.

When I say I've checked the trace layer, I've only checked the bottom trace layer, I haven't checked the top trace layer. Is there any any device I can construct with Arduino, etc which automatically checks if the trace layer is working fine?
 

crutschow

Joined Mar 14, 2008
29,466
Some keyboard switches use a conductive rubber-like material to make contact across a gap in the PCB trace when the button compresses the material against the trace.
Can you look at that on your keyboard where the buttons make contact?
 

dl324

Joined Mar 30, 2015
14,303
When I say I've checked the trace layer, I've only checked the bottom trace layer, I haven't checked the top trace layer.
You're going to have to look at the top layer where the keys make contact with the board.

If the keyboard is new, is it new enough to still have a warranty? If not, you're going to have to disassemble and look at the contacts for the problematic keys. The keys probably have a carbon compound on the bottom that contacts traces on the PC board. I think it's more likely that the problem will be residue (some oily compound) preventing the keys from closing contacts.

I had that happen with a TV remote that had buttons that needed more and more pressure to work, until they eventually stopped working completely. I bought a replacement at Goodwill and took the other one apart. I saw the residue, cleaned it, and the remote is working again.

If the keyboard was older, having worn traces would be more feasible; but my remote was 25 years old and there was no erosion of the contacts.
 

MrSalts

Joined Apr 2, 2020
1,506
If the buttons are blister "bubble" contacts, you're going to have trouble fixing it because the blister may have firmed poorly during the manufacturing process. Or the conductor on the blister may have been printed poorly.
 

Thread Starter

bypassrestrictions

Joined Jun 1, 2021
94
Some keyboard switches use a conductive rubber-like material to make contact across a gap in the PCB trace when the button compresses the material against the trace.
Can you look at that on your keyboard where the buttons make contact?
I wish I knew the name for that, but I found what you are saying to be present on some keyboards, not in the one I have, mine is a regular keyboard. Inside of my keyboard looks very much like the innards of the keyboard in this video:


You're going to have to look at the top layer where the keys make contact with the board.

If the keyboard is new, is it new enough to still have a warranty? If not, you're going to have to disassemble and look at the contacts for the problematic keys. The keys probably have a carbon compound on the bottom that contacts traces on the PC board. I think it's more likely that the problem will be residue (some oily compound) preventing the keys from closing contacts.

I had that happen with a TV remote that had buttons that needed more and more pressure to work, until they eventually stopped working completely. I bought a replacement at Goodwill and took the other one apart. I saw the residue, cleaned it, and the remote is working again.

If the keyboard was older, having worn traces would be more feasible; but my remote was 25 years old and there was no erosion of the contacts.
It is new and it is under warranty but I don't want to send it to service, I want to repair it myself. In the keyboard I have, it is very much like the keyboard mentioned in the video above, the buttons are plastic, and there is a rubber layer and then a transparent trace layer, this interfaces with the PCB.

I can't notice any carbon compound on the bottom of the rubber layer, it appears to be just rubber. From my observation, there are two trace layers separated by an insulating layer, this prevents the top layers traces from coming in contact with the traces of the bottom trace layer, at the contact points of top and bottom layer, the insulation layer has holes, this allows the top trace layer's contact points to make connection with the bottom layer's contact points when a button is pressed.

How can I check the top layer's traces? Most of the videos I find on the net only show how to check the bottom layer.

If the buttons are blister "bubble" contacts, you're going to have trouble fixing it because the blister may have firmed poorly during the manufacturing process. Or the conductor on the blister may have been printed poorly.
It incorporates that but has a different variation, you can see what the innards of my keyboard looks like in the video I mentioned in this post.
 

Thread Starter

bypassrestrictions

Joined Jun 1, 2021
94
Did he ever say that he actually fixed it? I jumped around. His voice was annoying and his pace was too slow. I'd rather give money to people making cat or dance videos...
He doesn't say if he fixed the keyboard. I only showed it because I didn't give information about what the inside of my keyboard looks like.
 

MrSalts

Joined Apr 2, 2020
1,506
Someone taught that person incorrectly.
The copper traces oxidize. You can refresh the copper surface by polishing with steel wool, a pencil eraser, scotchbrite pads, or fine sand paper. Wipe the silicone polymer pads with rubbing alcohol if you really believe the silicone rubber somehow contains or magically turns into silicone oil but not really necessary. Also, it doesn't help because the OP confirmed this is not that kind of keyboard in post #5.
 

AlbertHall

Joined Jun 4, 2014
11,952
I have fixed several remote controls that had an oily substance on the pads under the buttons but none outside the button area. Where did this substance come from if not the buttons?
 
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