GT and the Inner Tensions of Metals
Working with scientific institutes over the last few years has heightened our sensitivity towards the expectations concerning our galvanic layers.
Besides hardness, ductility, electric conductivity, and other specifications customers often wish for particularly even layers.
This is very understandable; nobody wants to commit their parts to have them plated and receive them back bent and crooked.
However, this seemingly simple wish for evenness is not as easily realized as one might think. “Inner tensions” are known and feared by electroplaters of all kinds.
What are these inner tensions?
Galvanic layers build up in grid structures. For example, if only copper atoms are deposited, the grid takes a cubic form. However, electrolytes are usually enriched with additives that cause, for example, bright surfaces. Those additives (or even ions that would not belong into the electrolyte in the first place, like nickel) get built into the grid, too. But since they are of different sizes than copper ions the grid structure gets crooked.
It may also happen that places inside the grid structure get skipped, causing flaws in the grid which also lead to distortion.
Inner tensions in metals manifest in two directions:
- Inner tensions of convex alignment (compressive stress)
- Inner tensions of concave alignment (tensile stress)
Bright copper depositions often show the second type of inner tensions, and it’s generally not easy to change this.
What we do for even depositions:
1) Monitoring: We developed internal procedures that allow us to always keep track of inner tensions of our depositions. Therefore, we can adjust electrolytes in a very timely manner.
2) Adaptation of our bath chemistry (link): If inner tensions exceed the norm, the electrolyte in question must be nurtured into shape.
Advantages of galvano-t
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