Atmospheric Effect on Dendrite Growth

Well, obviously, the atmosphere can have no direct affect on dendrite growth, as it doesn't touch the dendrite growth region. Some gasses can dissolve in electrolytes, if not sealed, and may have an effect.

Thanks, but tin whisker as form by a different phenomenon. They are not dendrites.

Cheers

see

WayneL

Thick-film hybrid circuits often used silver for the circuit traces, and dendrite growth between traces which had a DC voltage difference was a serious problem. The solution was to alloy the silver with palladium, which either eliminated or greatly reduced the growth. I'm not enough of a chemist to know why, but I'm sure anyone interested should be able to find quite a body of information in publications relating to hybrid circuits. The IEEE has a professional group which deals with hybrid circuits, and I'm sure the associated Transactions journal has a lot about this.

Roy Lewallen

Most theories of dendrite growth attribute this habit to differential concentrations of impurities on certain crystal faces, edges, corners, etc. But these theories were devised for metal melts.

J.J.

Bell Labs may have published info on dendrites as the telephone companies had trouble with dendrites in sealed crystal filters. One of the repair practices was to put a "megger" on selected connections and burn the dendrite clear. I seem to remember Bell Labs publishing something on the problem. The filter problem (I think) involved Tin. The problems I remember were in the 1950's time frame.

Bill K7NOM

Marconi Co uk had problems with tin whisker growth on electro tinned brass parts in crystal filters. Grew 10 to20mm whiskers of tin in an inert nitrogen atmosphere within a year or so. Shorted out the variable caps mostly. When the tin plating was oil immersed to re-?flow after plating the problem went away. Relevant to replacing lead with tin for solder process. At the time it was said that the plating process resulted in stress in the tin lattice.

Oxygen would of course be reduced along with Cu++, and it's hard to say whether this could affect dendrite growth. My guess is not, but I can't be sure. Since you are experimenting with it, try it out. Certainly I would be pretty confident that an Ar atmosphere would not affect dendrites, as Ar is inert, and it is hard to see how the small ampount that would dissolve in the electrolyte could have any effect at all. CO2 - well, hard to say. It would affect the pH, and that itself might cause a change.

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Eagle Pitcher (the battery company) had some problems with their sealed = batteries and dendrite growth when dischaged and left un-used. I recall = a topic on wiskers, but I dont know if its the same chemical process.

Cheers

I am trying to calculate if the atmosphere has an affect on the growth of dendrites, e.g. copper. Eliminating the atmosphere and growing dendrites in a vacuum may prove to be difficult to run, as the electrolyte will outgas and thus evaporate. However, if a test was constructed using Argon or any other inert gas would one notice an effect? Consider another test. Rather than using an inert gas, used CO2, could this effect the growth of a dendrite. Are there papers on the atmospheric effect on dendrite growths? Can anyone propose any potential effects the atmosphere may have? Or is the electrolyte the "dendrite's atmosphere" and this vehicle may pick up atmospheric contaminates that could produces various species?

Cheers

WayneL =20 Most theories of dendrite growth attribute this habit to differential concentrations of impurities on certain crystal faces, edges, corners, etc.=20 But these theories were devised for metal melts.

J.J. Bell Labs may have published info on dendrites as the telephone = companies had trouble with dendrites in sealed crystal filters. One of the repair practices = was to put a "megger" on selected connections and burn the dendrite clear. I seem to remember = Bell Labs publishing something on the problem. The filter problem (I think) involved Tin. = The problems I remember were in the 1950's time frame.

Bill K7NOM

What is going on with this thread? My reader is choking on it big time. Won't dwonload any headers after this one:(

Bob

Back in the 70's, we had a problem with dendritic growth inside of T-03 power transistor cases. The experts at the time couldn't determine the cause but speculated that it was due to migration of the hard die solder. How and why was never explained. The lot of transistors was replaced and the problem "went away."

Al