Metric Formula  for the Deposit Stress Analyzer System:

CALCULATIONS: (For Thickness)

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 measuring block scale 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                   = cm

.               D (7.74 cm²)

T = deposit thickness in cm

W = deposit weight in grams,

D= Density of the plated material, g/cm³ (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:

Note: If using x-ray for thickness it would = T after the deposit thickness is known and the number of increments spread between the test strip leg tips has been determined, the deposit stress can be calculated thus:

Calculate the Deposit Stress:

S = UKM÷3T                          where:                 S = kg/cm²

U = number of increments spread (See Table B for conversion),

T = deposit thickness in cm,

K = the test strip calibration constant will be labeled on each lot of test strips,

M= the modulus of elasticity of the deposit ÷ by the modulus of elasticity of the substrate material (See Table A).

TEST STRIP MATERIAL RECOMMENDED PLATING CONDITIONS FOR PLATING See table 2 page 8 of DSA Brochure

Note: If the test conditions cause the test strip leg tips to spread beyond 20 units, reduce the deposition time and the deposit thickness for the test to improve accuracy.

FOR PN: 1194 – COPPER–IRON ALLOY 0.00508 cm thick (deposit stress from 105 to 10194 kg/cm²)

DEPOSIT STRESS M value for nickel plating M = 1.715 The correction factor for the difference in the modulus of elasticity between the deposit and that of the substrate = EDeposit ÷ ESubstrate = 2110813 ÷ 1230797 = 1.715 kg/cm².

FOR PN: 270NI – PURE COLD ROLLED NICKEL 0.0011 INCH THICK  (deposit stress from 14 to 4218 kg/cm²)

DEPOSIT STRESS M value for nickel plating M = 1.0000 The correction factor for the difference in the modulus of elasticity between the deposit and that of the substrate = E Deposit ÷ E Substrate = 2110813 ÷ 2110813= 1.0000 kg/cm²

TABLE A                                        (Values for M)

     
Test Strip Material        1194  270NI
E Substrate       1,230,797 2,110,813
Stock Thickness, cm       0.00508 0.002794
Metal      E Deposit Value   M M
Cadmium   562,883   0.4573 0.2667
Cobalt   2,528,896   2.0547 1.1981
Chromium   2,151,601   1.7481 1.0193
Copper   1,121,688   0.9114 0.5314
Gold (Soft)   787,221   0.6396 0.3729
Nickel   2,110,813   1.715 1.0000
Palladium   1,193,068   0.9693 0.5652
Platinum   1,743,715   1.4167 0.8261
Rhodium   3,660,781   2.9743 1.7343
Sliver   774,984   0.6297 0.3671
Tin   414,820   0.337 0.1965
Zinc   984,026   0.7995 0.4662

E Substrate= modulus of elasticity of the substrate material (test strip material).

E Deposit = modulus of elasticity of the plating deposit.

M= modulus of elasticity of the E Deposit ÷ modulus of elasticity of the E Substrate

Table B   (U factor conversion) (*English is the increments spread on the Deposit Stress Analyzer)

Note:  If the increments spread is 6.5 the Metric would be 1.1598

English Metric               English Metric     English Metric
0 0         8.5 1.5172   17 3.034
0.5 0.0891   9 1.6066   17.5 3.1236
1 0.1782   9.5 1.6957   18 3.2129
1.5 0.2675   10 1.785   18.5 3.3025
2 0.3569   10.5 1.8741   19 3.3914
2.5 0.4452   11 1.9635   19.5 3.4807
3 0.5353   11.5 2.0528   20 3.5688
3.5 0.6247   12 2.1419   20.5 3.6595
4 0.7138   12.5 2.2308   21 3.7486
4.5 0.8031   13 2.3206   21.5 3.8377
5 0.8917   13.5 2.4097   22 3.9273
5.5 0.9816   14 2.4991   22.5 4.0161
6 1.0707   14.5 2.5882   23 4.1057
6.5 1.1598   15 2.6773   23.5 4.1951
7 1.2497   15.5 2.7667   24 4.2842
7.5 1.3388   16 2.8558   24.5 4.3735
8 1.4279   16.5 2.9454   25 4.4629