Author Topic: Fat traces?  (Read 2919 times)

markeebee

Fat traces?
« on: November 24, 2010, 09:29:38 AM »
When I etch a board, I think it looks nicer if the traces/tracks are as fat as possible, rather than thin spindly lines.  Also, it etches quicker.

Is there any real reason to keep the traces thin?  I'm guessing that they might pick up noise, and there might be some capacitive effect, but I've never noticed a problem.

R.G.

Re: Fat traces?
« Reply #1 on: November 24, 2010, 09:39:56 AM »
For audio, fat traces are fine. Thin traces let you get more traces on the surface. If you can get the circuit laid out with fat traces, it's more durable, as wide traces are more immune to cracking, if somewhat harder to solder. Ground planes are the ultimate "fat trace" and can be a PITA to solder.
R.G.

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markeebee

Re: Fat traces?
« Reply #2 on: November 24, 2010, 10:00:05 AM »
Thanks RG.  If you could just explain to my doctor that fatter is better.....

Mark Hammer

Re: Fat traces?
« Reply #3 on: November 24, 2010, 11:19:07 AM »
When I see a layout for something I like that has thin traces, I make the image greyscale, then use a "soften" filter to smudge it.  That spreads the traces out a bit, so I then use a "highlight/midtone/shadow" filter to darken those greys that have been added on the perimeter of all traces and pads.  A few runthroughs until its thick enough, then I flip back to a black and white image to clean up the excess.  At that point, there may be a few places where the expansion of pads has made thigs perilously close and at risk for solder bridges.  So I digitally remove some black from the image with a paintbrush or other tool, just to make some space.

Keep in mind as well that with application of heat, some photopaper will occasionally "splat out" so that traces become fatter than they originally were.

And yes, groundplanes can be a royal PITA if too big.  I always try to have a ground-surround on boardsm, but if any segment of it covers too much surface area, it serves as a heat sink when soldering, and makes for lumpy clumpy solder joints.  So I may try and reduce some of that surface area, whether digitally, or with an X-acto blade after transfer (but before etch), just to avoid the problem.

davent

Re: Fat traces?
« Reply #4 on: November 24, 2010, 03:41:16 PM »
With fat traces in ExpressPCB, and i'm sure other programs, you can create pads in large areas of copper that connect to the larger copper area with thin traces so it's much easier to solder to those pads.

These have a bit of that going on.





dave
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Mark Hammer

Re: Fat traces?
« Reply #5 on: November 24, 2010, 03:50:04 PM »
I often find myself editting Express PCB layouts to get rid of these.  They're sound in principle, but I like to tin the entire board, once etched, and those big ground planes interfere, even if the thin connecting traces make soldering of individual pads easier.

Meh.  personal taste.