I have attached some of PCB's showing strange PCb track. (zoom out file to 50% for clarity).

What is their purpose. Shouldn't they be straight way connected?

 

Hello,

The wiggled lines can be seen as delay lines.
This is done to have signals to arrive at the same time at the end of the line.

Bertus

 

The wiggled lines can be seen as delay lines.
This is done to have signals to arrive at the same time at the end of the line.

Bertus

Indeed -- Or, perhaps, printed inductors...

Best regards
HP

 

Since someone went to a lot of trouble to make all the wiggles I doubt they should "be straight way connected".

Inductance is one possibility, equal delay another, so is some small but defined resistance.

What is this thing where you found this board?

 

Those lines look eeriely similar to heating pads... perhaps they're there to keep the PCB at a constant temperature because it's a very sensitive type of circuit?

 

I can't know the reason in this particular circuit, but when we did things like that on computer motherboards, it was in order to have (electronically) equal trace lengths. It might make a difference if it is clock distribution, or parallel data.

 

they look like printed inductors, quite a bit of consuumer electronics had to put them on to reduce em radiation. the govt put on limits for interference.

 

It might make a difference if it is clock distribution, or parallel data.

One last possibility is high accuracy analog to digital conversion

 

It would help to know the boards application?
Max.

 

It is very fast DIO board (upto 50Mhz).
I have noticed that tracks which had small distance between them, only those where made wiggled.
Tracks which had large distance very straight lines.

So I think correct reason would be
This is done to have signals to arrive at the same time at the end of the line.

 

if the wiggles were to make the signals arrive at the same time, they would probably be different lengths to compensate for the rest of the board or circuitry.

 

if the wiggles were to make the signals arrive at the same time, they would probably be different lengths to compensate for the rest of the board or circuitry.

Except for the two at the left, they are different lengths,

 

those wiggles dont look very long, it takes about 11 inches to make a nano second of delay, unless that is an extremely high frequency board (not normally phenolic pcb) the delay difference would be neglagable.

 

Found in the Wiki description on Delay Lines.

"In modern computers operating at gigahertz speeds, millimeter differences in the length of conductors in a parallel data bus can cause data-bit skew, which can lead to data corruption or reduced processing performance. This is remedied by making all conductor paths of similar length, delaying the arrival time for what would otherwise be shorter travel distances by using zig-zagging traces."
Max.

 

Hello,

The wiggled lines can be seen as delay lines.
This is done to have signals to arrive at the same time at the end of the line.

Bertus

The technical term is: "data race".

 

Indeed -- Or, perhaps, printed inductors...

Best regards
HP

Printed inductors are mainly spirals - on some of the pld floppy disk drives the spindle motor was pretty much built on a circular PCB, the coils were flat air-cored units glued to the PCB, these were surrounded around all of them by a zig-zag track - that was the PG winding.

 

and most of those printed circuit boards are fiberglass not phenolic. phenolic isnt stable enough and the impedance changes with humidity. plus the length of the traces isnt enough to make much difference at the frequencies that phenolic will work at. even the curves in the traces have to be proper, a right angle like those will cause an impedance bump with reflections. have to read up on stripline or microstrip for more info if you want it.

 

is there a temperature sensitive component above that section of the board? Heat sensor, crystal, ... ? I agree that it could be for a heating element.

There are bed heaters for RepRap 3D printers using a similar design on PCBs - no though-hole components on-board though.