Dendrites from the Anode?

Hi

I have been conducting some test on dendrite growth on gold plated copper (with nickel barrier) printed circuit board pads. After applying a small quantity of water and biasing with 15v I observed a dendrite emanating from the cathode. From the literature I have read the dendrite grows from the cathode. Placing 15 volts directly on the pads with no current limiting caused large quantities of gas bubbles that damage the dendrites.

So, I placed a resistor in series 500K ohms.

However, this produced a dendrite from the anode. I have measure the polarity and it is correct. A search on the internet reviled a site that said batteries can produce

anode to cathode dendrites if overcharged.

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Is this correct and if so how can dendrites for from on the anode surely metal ions (M+) migrate from the anode to the cathode.

In addition if the circuit is connected with the resistor (1M ohms) in series with the earth then dendrites grow from the anode.

15v+ - --- gold plated Cu pads --- =A6 1M ohm =A6 GND

However, if the resistor is in series with the +V supply then dendrites

grow from the Cathode??

15v+ - =A6 1M ohm =A6 --- gold plated Cu pads ---=20 =A6=20 GND=20

Cheers=20

WayneL=20

Reply

Reply to
WAYNEL
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If the location of the resistor changes the effect, then I expect you=20 have a supply that is not completely isolated from ground and an=20 experiment that is not completely isolated from ground (or other=20 inadvertent conduction paths). Try it with a 9 volt battery and the=20 whole experiment in a glass dish sitting on an inverted glass dish and=20 see if it doesn't change the result.

Reply to
John Popelish

I read in sci.electronics.design that WAYNEL wrote (in ) about 'Dendrites from the Anode?', on Tue, 23 Aug 2005:

You have three metals present. Under those conditions, the most electropositive migrates to the cathode, while the most electronegative migrates to the anode. This is a bit simplified, but it explains the basic mechanism.

If that really happens, and you can explain it, you stand to get a Nobel Prize. But I suspect that your experiment or report contains an inadvertent error.

--
Regards, John Woodgate, OOO - Own Opinions Only.
If everything has been designed, a god designed evolution by natural selection.
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Reply to
John Woodgate

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