PC board traces

[NATY]

just a matter of curiosity,....why is it that some boards, instead of a point to point trace

instead have a squiggle to them...thought about parallel trace interference

and also some small series resistance (uOhm ? ) or is there some other

purpose,....or just cosmetic?..

 

[schmitt trigger]

Some designers use the copper traces as low valued resistors...for instance to measure a current.

Although esentially free, the problem with this approach is twofold:

1) The initial tolerance, since it depends how accurately the board manufacturer controls the etching
2) Worse still, the temperature drift. Copper has a HUGE temperature coefficient, about +3.9% each 10C. Since the current will produce self heating, plus the heating from other components make this approach very low precision, unless temperature compensation is applied.

I've also seen traces like this used as fuses of last resort. In other words, if an overcurrent condition occurs, the trace will burn up and prevent a fire. The problem here is the lack of precision....same as 1) above. Additionally the board is rendered useless.

 

[RCinFLA]

The most common use of 'squiggle' lines is for balancing time delay on high speed memory lines.

The attached picture is of Sony PS2 portable player, processor to memory connections.

 

[Sceadwian]

Varied distance between two lines will help avoid setting up a transmission line situation, the varied track will not have a single impedance, could very well act as a bandpass and band reject filter although at specific frequencies.

 

[crutschow]

A squiggly line can also be used for a low value inductor in RF circuits.