Hardware Design Question

[yummy_potatoes]

While I was looking around on the bottom of the motherboard, I noticed something about the traces that appeared to be buses: some of their wires have a LOT of "kinks" in them.

I didn't see anything like this on the X3, but then, those traces are hidden well by the enamels and color coatings.

I was just wondering why most motherboards in general have these same patterns (I've since looked at several computer motherboards.)

Is it for interference reasons, or simply to make all the traces the same length?

 

[Martin C]

It's basically to reduce the amount of layers a PCB has.

No two tracks can cross - this would involve a third layer (as most PCBs are a top and bottom layer).

Therefore, tracks may need to be routed in order to allow for other tracks to get to their destination too.

Although there's more track than needed, it's still a lot cheaper than a three-layer PCB.

Because the tracks are usually thin, resistance is very low so it won't affect data lines.

Martin

 

[Hudson]

Sometimes traces snake back and foward on themselves to keep them the same lenght also.
I used to work in R&D at a router company and on our 1+ gig stuff we had to careful to keep the traces on the buses the same lenghts, made for some interesting looking prototypes at times

 

[Martin C]

Sometimes traces snake back and foward on themselves to keep them the same lenght also.
I used to work in R&D at a router company and on our 1+ gig stuff we had to careful to keep the traces on the buses the same lenghts, made for some interesting looking prototypes at times

oops- yes, that too!

Martin

 

[yummy_potatoes]

Thanks, I never noticed it on anything but stuff with high speed ICs and fairly large data busses. It's amazing that a device could be transfering data so fast that having the length off just the tiniest bit would throw the system out of whack.

 

[TokenUser]

Thanks, I never noticed it on anything but stuff with high speed ICs and fairly large data busses. It's amazing that a device could be transfering data so fast that having the length off just the tiniest bit would throw the system out of whack.

Not to mention eliminating right angles on the trace so electrons don't go flying "off the track" and cause interference

 

[Hudson]

I beleive that the right angels are taken off so the electrons don't slow down too much at the corners :wink:

....joking of course :lol: