MIL-STD-865D
as a constant flow rate and the use of abrasive type covers such as "Scotch Brite" it is possible to deposit layers of metals such as nickel in excess of 0.030 inch without layering or sandwiching. The solution manufacturers list a normal maximum thickness build-up for each solution in their literature.
b. Use a lamination technique whereby layers of a harder more difficult to activate materials are laminated with a softer, more easily activated material. A typical example would be to plate 0.002 inch copper acid, polish and repeat until the
desired thickness, is obtained. Copper acid deposits are easy to activate and, therefore, a simple reliable procedure is being used. Grain growth is in horizontal layers for soft metals and vertical layers in hard metals. Thus, alternating layers of hard and soft deposits dissipate or eliminate stress much the same as the theory behind plywood.
4.3 Anodes.
4.3.1 Anode materials and shapes. The removable anodes are available in a wide range of standard sized and three basic shapes. They are as follows:
a. Cylindrical - for plating inside diameters. b. Concave - for outside diameters.
c. Flat or block shaped - for flat shapes
d. Bulk blocks of graphite material are available for manufacturing special shapes.
The anodes shall be of high purity dense (minimum bulk density of 1.74 glcc and a maximum grain size of 0.008 inches) graphite, platinum, platinum plated titanium, of 90 percent platinum and 10 percent iridium unless otherwise authorized by the responsible engineering organization. Separate anodes should be kept for use with each plating solution. Each anode should be dedicated to a solution and should be identified with solution code and polarity. Anodes that have been used for reverse current cleaning and etching operations should be marked as such and should not be used with forward current.
4.3.2 Anode selection.
4.3.2.1 Anode selection for preparatory steps. The cleaning, de-oxidizing, etching and activation steps usually require much less time than the plating steps. Therefore, close matching of the anode for preparatory steps is not as important as in the plating steps. To insure that thorough and uniform preparatory operations have been carried out, it is desirable to use adequate size tools for those operations, recommend that the preparatory tools cover a minimum of 10 percent of the area to be plated.
4.3.2.2 Anode selection for plating steps. Metal is deposited essentially only in the area of the tool to work contact. As a result, the following should be considered when selecting an anode:
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