for those new to PCB layout.? Thermal relief pads are very important as they enable good solder connections where otherwise the heat from the iron would be drawn-away by attached surrounding copper.

Funny thing,

I just finished checking a fairly complex PCB layout (not Ham related) for a product I am developing. I notice that many places where a trace runs between two pads, it is NOT centered, and therefore the spacing is not optimized. The designers tell me if it passes the design rule distance checks (DRC) in the software (Altium in this case), it's good and no further work is done.

I guess I am an old dinosaur who did a lot of layout in the old days and made sure using eyeballs that every trace (most of which were not "impedance designed") was centered between adjacent non-connected pads.

I am about to be extinct, or does anyone worry about this kind of stuff?

73,

Paul K2AYZ

开云体育

If impedance, crosstalk, or voltage are not an issue and the spacing meets the criteria specified, no, I don’t think it matters. ?Aesthetics (typically) isn’t a design issue in PCBs, at least not for the traces. ?All engineering is a trade off. ?Routing a trace to be centered would mean (probably) a longer trace, which is a BAD THING albeit a very minor bad thing.

Hi, Clark,

Thanks for the feedback - I am now proud of my acceptance of the efficiency of the uncentered traces!?

I have been burned by the care needed to route traces for 100 MHz and Gig Ethernet traces, but that's another story.

Always something to learn.

73,

Paul K2AYZ

开云体育

Robert: w0w, you taught me something! ?I never understood why those were there!!!!!

Un-centered traces between evenly spaced pins such as those on ICs and connectors offends my sense of artistic perfection.? Just the way my mind works (or doesn't). ;-)
--
Jon Titus, KZ1G
Herriman, UT USA

You dinosaur, me pond scum...
Red Tape, Blue Tape, Black Tape, DIY pads.....6x8 foot tapeups...? Ah, the xxxx old days!

I have been using DipTrace since it was introduced for home projects.? For 'aesthetics' I set the design rules for a generous keep away.?
Paul, I believe the expression is "pride in workmanship".

Kicad 5.0 is now out with many significant improvements
? ??

Yes, the days of staring for hours at a light table with six layers of pin registered mylar, at four times actual size. Trying to figure out where to cut and pull up tape and pads to make a design revision.?

Absolutely true genius was demonstrated by many board designers as they, time after time, pulled off the impossible task of adding components and layout changes on an already overpopulated layout.

The allure of electric drafting erasers. Well, that's another topic.?

On a side note, a company I worked for designed their own graphics processor chips. They had layer plots hanging from the walls of a two story room. I was looking at one closely and noticed drawings of Dilbert and crew tucked into some the obscure areas of the top metal layer.

Tom, wb6b

--

开云体育

Yeah, I had to do that. ?One time I was working over a large backplane board. ?I, and the board layout person, missed one TINY detail. ?The daughter board connectors were swapped, left for right, oops. ?We ended up building the board with the connectors on the back side for one of the prototypes. ?It worked.

I remember at a small startup, we we had a run of prototype boards made. The people assembling them were complaining that the ICs were going in tight. When it came time for testing, we plugged a board into the backplane of the main system.?

The new boards were one row of pins narrower than the full width to fit the dual 44 pin card edge connectors.?

We used a great little PCB shop, nearby. Small shop, but great service. He, looked into what happened and was deeply apologetic. He apologized that his son had been with him, at the shop, over the weekend and played with the camera adjustments, without being noticed.

That was a big lesson for all of us to not discount feedback when it seems it must be odd but no big deal.

The board shop made new boards overnight for free. I think we ate the cost of the parts and labor, as we were amiss in not doing QA on the boards. Some blame was past back and forth between us, but we got over it and chalked it up to lessons learned. ?

Yes, it was truly a lesson, that even though we were ourselves pushing our limits to get a design finished, we were amiss in not stopping and covering the basics when something was commented about and questioned by folks.

One clarification to earlier an post, I was the electronics engineer, not the board designer. I could wear many hats and do board tape-up and modifications. I was in awe of what the the true board designer professionals, at the companies I've worked, could do and relied on their talent. I mostly determined critical layout constraints for ground loops, important signals, crosstalk considerations, heat generation and overall shape of the design.?

Tom, wb6b