### Any deposited metallic coating can be tested for stress using the DSA Method

Nickel Sulfamate Bath Plating Conditions – See Brochure for select work process conditions:

 Recommended Bath Temperature as Degrees Fahrenheit 130 °F Current Density in Amps / Square Foot 30 Plating Current as Amperes 0.25 Plating Time: Minutes and Seconds 4 Min. 12 Sec. Average Deposit Thickness in microinches 100

CALCULATIONS: (for Thickness example is for nickel plating)

The deposit stress is compressive if the resist is on the outside of the Test Strip legs.

The deposit stress is tensile if the plating is on the outside of the Test Strip legs.

It is necessary to know the total units or increments spread between the plated test strip leg tips from both sides of the center line on the Deposit Stress Analyzer and the average deposit thickness in order to calculate the deposit stress. If the deposit thickness cannot be determined by actual measurement, it can be calculated as follows:

T =              W                                    = Inches

‘            D (7.74 cm²)( 2.54cm/inch)

T = deposit thickness in inches,

W = deposit weight in grams,

D= Density of the plated material, g/cm³ (see Table of Density Values for the D)

A = surface area in square centimeters. Since the plated surface area on a test strip is 7.74 square centimeters, the formula for nickel thickness can be shortened as follows:

T=  0.0509 (W divided by D)

To determine the thickness of a nickel deposit that weighed .0349 grams, the calculation would be:

T= .0349 x .0509  = .000200 inch

‘      8.88

After plating a given test strip per the instructions given on page two, solve the equation

S=UKM÷3T,    where

U = Total number of increments spread between the test strip tips: example (2.4+3.1=5.5).

NOTE: The plating test should be continued until the test strip legs deflect up to 20 units spread for the most accurate results. The required plating time can be determined experimentally by examining the degree of spread after each minute of plating.  Metallic deposit recommendation plating thickness is 100 microinches unless the deposit is soft such as tin.  If the stress is near zero, a reading as low as 1 unit may result.

T= Deposit thickness in inches.
M= 1.0000 for PN: 270NI Test Strips the correction factor for the difference in modulus of elasticity values between the deposit (in this case nickel).

* Note: once you determine what the Modulus of Elasticity in PSI then divide that number with the Modulus of Elasticity of the Substrate material (PN:  270NI Pure Nickel Test Strip is 30,000,500) this will give you the M Value.

For plating Gold the Nickel 270 NI Test Strip  Example: 11,200,000 ÷ 30,000,500 = 0.3733

*If your Modulus of Elasticity number is in GPA ÷ that number by 145 to get the PSI

K= The calibration constant value provided by the manufacture.
S= The internal deposit stress in pounds per square inch.

Record the value of S for each.

TEST EQUIPMENT- – All Specialty Testing equipment is designed for 120 Volt

• PN: 800L Plating Test Cell (price includes PN: 404 submersible mini pump).
• PN: 3046 Electric Immersion Heater (Note: Heater maintains ± 2° F).
• PN: 683 Deposit Stress Analyzer Stand
• PN: 15020-2 Rectifier to supply the direct current amperage for plating. A constant current constant voltage power supply is recommended preferably a zero to two amp output with low ripple.
• The desired Test Strips.
• Two Anodes 2 3/8″ (61mm) x 2 3/8″ (61mm) (Can be purchased from Kocour Company).
• GraLab Timer 60 Minutes or equivalent with automatic shut off (Can be purchased from Kocour Company).

Test Set up
1- Plug the rectifier into the automatic timer, which is plugged into a 120 Volt source.
2- Place the anodes in the plating cell anode pockets and connect the red leads to the anodes (If using the 785 series plating cell skip to #5)
3- Place the heater in the 800 series plating cell (see photo above).
4- Set the pump slide bar to its lowest setting. Dampen the suction cups on the submersible pump and fasten it to the side of the cell so it rests on the cell bottom with its side located ½ inch from the cell end wall and the outlet directed toward the cell wall opening. Agitation in the plating side of the cell must be limited to prevent the test strip legs from swaying to favor one anode over the other (see photos above).
5- Fill the cell with the plating bath solution to within 1/2 inch of the top of the cell (If using the 785 cells skip to #8).
6- Plug the heater into the temperature controller and the pump into a 120Volt source (for the 800 series plating cell).
7- Heat the plating solution to the operating temperature (for the 800 series plating cell).
8- Connect the red positive lead from the power supply to the aluminum lug contact provided on the cell. Connect the red leads on the cell to the respective anodes.
9- After following the test strip procedure below for cleaning you will then use the black negative lead to fasten a test strip to the stainless steel support mounted on the cell.
Test Procedure
1- Soak a test strip in a soak cleaner solution at 110-120 °F for 30 seconds then water rinse.
2-Immerse in a 10% by volume hydrochloric acid solution for 15 seconds at room temperature then water rinse and alcohol rinse. Dry completely and weigh the test strip. Record the starting weight.
3-Turn the agitation pump ON and set the timer for the appropriate plating time.
4- Clip a test strip to the stainless steel cross support so the test strip is centered between the cell walls. The test strip leg tips should be approximately 1/16 of an inch from the plating cell bottom.
5- Using a test strip that has been used before, turn on the power supply and adjust at the desired amperage.
6- Remove the sample test strip and replace it with the weighed test strip and begin the plating test.
7- If the rectifier is plugged into the timer it will end the plating cycle.
8- After the test strip is plated remove the test strip from the cell.
9-Rinse the test strip in water, and then rinse it in isopropyl alcohol.
10-Lay the test strip on a paper towel and blot it dry.
11- Place the test strip on the measuring stand. Read and record the total increments spread on both sides of the zero as the value for U (example 2.4+3.1=5.5).
12- Weigh the plated test strip and record the final weight. Subtract the starting weight from the final weight and the difference = W.