keypad PCB

[haxan]

Hi, can anyone please help me on how to design a PCB for 4 x 4 keypad. Is it possible to make it out of one sided copper cladded board?

 

[jakeselectronics]

Of course its possible =]

Is this a matrix 4x4.... i.e. 8 external connections?

 

[haxan]

Yes it is. i cannot seem to find a way in which only one sided copper PCB can be used without jumpers.

 

[jakeselectronics]

im working on it....
in paint haha, gimmie 2 minutes......
there's got to be a way....

 

[jakeselectronics]

its a bit hard to visualise, but you get the idea....
It involves routing tracks underneath the pushbuttons...

 

[jakeselectronics]

and there's with no doubt a better way of doing it, but like i say, you get the idea

 

[haxan]

wow hehe nice. I have made one when i posted.. its as attached but it has jumper wires

 

[haxan]

oh yeah, i forgot to mention, i am not using standard push button. Using rubber keypad. tracks cannot go underneath them as they have a circular conductor underneath.

 

[jakeselectronics]

you got me curious, so I popped open a 4x4 single sided pcb keypad and this is what i found.

those dog-bone shapped links can be ran down and around below and inbetween the connection pins i think.

I haven't totally worked out how, but its probably possible with your type of pushbuttons.
Although it may look like spaghetti.

And another thing,
the contacts you have made, (2 parallel lines with the line inbetween), I would change that to resemble something that looks like the contacts on the pcb in the attachment.
So that they almost inter-lock. The more area of copper spread out over the whole circle below the push button contact, the more chance of a quicker/better/even contact.

 

[haxan]

its a professional board with jumpers (in blue). Home made PCB's its very hard to do this. Also the software i am using doesnt have curves. For that reason i have a sandwiched keypad style