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# Metric Formula for the Deposit Stress Analyzer System

Calculations: (For Thickness)

If the test strip legs are spread outward on the side that has been plated (plated side out and resist side in) the deposit stress is tensile in nature. If the test strip legs are spread inward on the side that has been plated, the deposit stress is compressive in nature. 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:

W
T  =    ──────────   =   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
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
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 6.25 the Metric would be 1.1152.

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