Hi guys

I come across this today, this is a PCB in a lithium battery for a cordless power tool (this: http://www.ryobi.co.nz/power-tools/products/list/family/brushless)

From my quick google search, I can understand that it maybe used to reduce reflection. But I don't understand these curly tracks are required in a lithium battery pack. I mean they don't do high frequency (in GHz range) in these battery right? So why did the design do that?

 

That board looks like it was laid out with tape and/or marker. I didn't realize this was done anymore. Very time and skill intensive.

Designed by North Korean workers in a slave shop?

 

Mmm... date codes suggest it was designed in 2012, lots of free PCB design tools available I believe.

 

lots of free PCB design tools...

None that produce work like that, AFAIK.

 

None that produce work like that, AFAIK.

I mean whoever designed the board could use one of those free tools, unless they really want to do it by hand.

 

It was done with a PCB drawing tool.
Some people are just insistent about converting corners to a radius (easily done with better tools).

The key indicator that it is a drawing program is that the radius around the vias is too consistent so the "gap" setting on the copper pours is used. See yellow circles. Nobody would cut tape that way.

 

Eagle can do those kind of curves.

 

The problem is that with sharp trace corners the electrons have to slow down too much, and then re-accelerate into the straight PCB trace. With the curved traces, they can lean into the curve and with appropriate safety gear lean all the way over so that their tiny little knees are scraping the trace. This cuts down on the resistance and improves their capacity for maintaining speed along the long PCB traces.

This picture of a high-speed electron leaning into a curved PCB trace was taken with an extremely high resolution electron microscope. Notice the curved trace just off the electron's knee

 

The problem is that with sharp trace corners the electrons have to slow down too much, and then re-accelerate into the straight PCB trace. With the curved traces, they can lean into the curve and with appropriate safety gear lean all the way over so that their tiny little knees are scraping the trace. This cuts down on the resistance and improves their capacity for maintaining speed along the long PCB traces.

This picture of a high-speed electron leaning into a curved PCB trace was taken with an extremely high resolution electron microscope. Notice the curved trace just off the electron's knee
View attachment 139964

In my bad-ass projects, the electrons don't wear no stinking helmets.

 

Fake. Here's the real microphotograph:

 

I used to draw PCB traces with sharp corners in the old days... until I noticed that the copper started peeling off at those sharp edges, and were also more prone corrosion over time ... those problems disappeared completely after I started drawing traces with a radius of at least 0.031" at the corners.

 

I used to draw PCB traces with sharp corners in the old days... until I noticed that the copper started peeling off at those sharp edges, and were also more prone corrosion over time ... those problems disappeared completely after I started drawing traces with a radius of at least 0.031" at the corners.

That's huge compared to the 5 mil track/ space I use in my designs.

 

That's huge compared to the 5 mil track/ space I use in my designs.

I normally use 0.013" wide traces, separated by at least 0.010", the thinnest traces I'm willing to risk are about 0.007" ... but you have to keep in mind that my etching technique is a bit unconventional.

 

I normally use 0.013" wide traces, separated by at least 0.010", the thinnest traces I'm willing to risk are about 0.007" ... but you have to keep in mind that my etching technique is a bit unconventional.

Interesting, he seemed to know what your trace width was before you said it.

 

Interesting, he seemed to know what your trace width was before you said it.

I actually got it wrong the first time around... I meant to say 0.015" radius at the corners, not 0.030" ... but the larger the radius, the better, anyway

 

That's huge compared to the 5 mil track/ space I use in my designs.

I do too when someone holds my hand and makes the PCB for me.
If you would read @cmartinez's posts, you'd realize he makes his own PCBs in his back yard - so his 0.007 - 0.010" traces are impressive.

 

In my bad-ass projects, the electrons don't wear no stinking helmets.

Oh yeah?! Well. It's your kind of electrons that drive insurance rates so high for the rest of us. Reckless and inconsiderate!

 

Oh yeah?! Well. It's your kind of electrons that drive insurance rates so high for the rest of us. Reckless and inconsiderate!

That's ok, my electrons don't carry insurance either. With a spin quantum number of 1/2, they don't go far and they don't move fast.

 

That's ok, my electrons don't carry insurance either. With a spin quantum number of 1/2, they don't go far and they don't move fast.

That explains the traffic jams in your designs... maybe you should consider tunneling them for a change...

 

Interesting. I find that helmets protect your brain. If you don't have a brain then you don't need a helmet. If you consider the nature of it all; helmet - no helmet - it all seems to sort itself out in the long run. Darwinism I think it's called. That's why I want to call for a ban on warning labels. Let nature solve the problem.