Compressive Stress– When the resist is outward. Tensile Stress– When the plated surface is outward.
|Test Strip||Tensile Stress||Compressive Stress||Range, PSI||Composition|
|1194||Yes||Yes||1,500 – 145,000||Copper-Iron Alloy|
|270NI||Yes||Yes||200 – 60,000||Pure Nickel|
Best results are obtained with a test set up similar to the above photograph. Anodes should be located at least three inches away from the Test Strip and should be positioned in a parallel plane with the Test Strip. Electrical contact should be made at the top of the Test Strip where there is a void in the masking material. The Test Strip should be immersed until only about 1″ remains above the solution level.
The plating current density should be adjusted with a given electrolyte so as not to cause deposit burning at the Test Strip’s tips, yet sufficient enough to conduct a rapid test. Preferably, the current density should be maintained at the approximate value at which the bath is normally worked.
NOTE: During plating a test strip is exposed to a uniform current density along the legs of the strip. The plating test should be continued until the test strip legs deflect up to 20 units and with a target thickness that does not exceed approximately 100 microinches for the most accurate results. Very low stress may show only 1-2 units.
Test Strip and Anode Considerations
|Metallic Deposit||Test Strip||Anodes*|
|Gold||270NI||Platinum Coated Titanium|
|Palladium||1194NI||Platinum Coated Titanium|
|Rhodium||270NI||Platinum Coated Titanium|
*Two are required, similar in composition, shape and size. Two Anodes 2 3/8″ (61mm) x 2 3/8″ (61mm) (Can be purchased from Kocour Company).
Note: For Electroless Nickel activation is not required for Chemically induced metallic deposition.