Etched labels

johnsmith1261 · Jan 12, 2010

Hi!

I've seen lots of examples of etching labels for a cheap substitution for silkscreening.

Like on this board (B1, B2, INT, HC-TK07):

I like this idea and generally use it on my boards, but are these floating copper parts totally acceptable electronically?

I mean, I've read that circuit grounds should generally be connected to protective earth in some way (for example through a 100 ohm resistor or directly) to prevent the circuits floating and getting statically charged.
The copper parts of the labels are floating now, so can't they introduce RF noise or be non-advisable in any way?

Thanks,
j

Diver300 · Jan 12, 2010

Isolated parts like that could charge to just about any voltage, but they are so small that there is little energy available. It is also highly unlikely that impedances could change fast enough to cause such a discharge. The impedance to some other part has to be high to hold the charge, but it would have to be suddenly low to release energy.

A person walking around gets charged up. When they touch something, that is a change of impedance and gives a danger of static discharge. A person obviously has a much larger capacitance to earth that a tiny bit of copper, and a person can charge up slowly and then all that energy is released when the person touches something.

Also an isolate copper area could resonate if there is any high frequency signals around. However, tiny bits like that would resonate at terahertz frequencies, so really wouldn't upset any common electronics.

johnsmith1261 · Jan 14, 2010

Diver300 said:
Isolated parts like that could charge to just about any voltage, but they are so small that there is little energy available. It is also highly unlikely that impedances could change fast enough to cause such a discharge. The impedance to some other part has to be high to hold the charge, but it would have to be suddenly low to release energy.

A person walking around gets charged up. When they touch something, that is a change of impedance and gives a danger of static discharge. A person obviously has a much larger capacitance to earth that a tiny bit of copper, and a person can charge up slowly and then all that energy is released when the person touches something.

Also an isolate copper area could resonate if there is any high frequency signals around. However, tiny bits like that would resonate at terahertz frequencies, so really wouldn't upset any common electronics.

Thank you for your quick and detailed reply!
It's much clearer now

Thanks,
j

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