Values for M For Various Deposit Coatings

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Deposit Stress Analyzer and Modified Stoney Formula M Values for Tensile Deposit Stress Applications

 Stock Material                      1194                       2042B                       270NI

*ESubstrate                         120,690                 144,830                        206,900

Stock Thickness, in               0.0020                   0.0015                         0.0011

 

Metal M Deposit 1194 Test Strip 2042B Test Strip 270NI Test Strip
Cadmium 31,720 0.263 0.219 1.53
Chromium 248,280 2.06 1.71 1.20
Cobalt 206,897 1.72 1.43 1.00
Copper 117,240 0.971 0.810 0.567
Gold 74,480 0.617 0.514 0.360
Nickel 206,900 1.71 1.42 0.9678
Platinum 146,900 1.22 1.02 0.710
Rhodium 289,650 2.400 2.000 1.400
Silver 75,860 0.629 0.524 0.367
Tin 59,310 0.491 0.410 0.287
Zinc 82,760 0.686 0.571 0.400

 

*E, modulus of elasticity of the substrate material in the Stoney Formula.

*M, modulus of elasticity of deposit ÷ modulus of elasticity of

substrate in the modified Deposit Stress Analyzer and Stoney Formulas.

**M, Modulus of elasticity of the deposit in the modified Deposit Stress Analyzer and Stoney formulas.

Stoney Formula:

S = ET² M δ   Where:                                                

                                                   3 L² t

S = Internal deposit stress in megapascals (MPa as dynes/cm²),

T = Substrate thickness in millimeters,

E = Modulus of elasticity of the substrate as determined by the manufacturer of the material

inMPa as dynes/cm²,

δ = Deflection = 1/2 the distance between the two test strip leg tips in millimeters (a dial

calipers is recommended for this measurement).  Note that inches x 25.40 = millimeters),

L = 76.2 mm, the substrate length in millimeters,

t = Deposit thickness in millimeters, and

M = Modulus of elasticity of the deposit ÷ that of the substrate, ED÷ ES

Deposit Stress Analyzer Formulas:

S= UKM¸ 3T

U = Total number of increments spread between the test strip leg tips

T= Deposit average thickness in inches.

M= Modulus of Elasticity, dynes/cm², of the deposit divided by that of the substrate

K= Calibration constant value provided by the manufacture.

S= Internal deposit stress in pounds per square inch, PSI

 

DSA METHOD FORMULAS WITH M INSERTED

The DSA formulas negate the need for use of the Stoney formula.  The DSA formulas that apply when the Modulus of Elasticity of the deposit does not approximate that of the substrate are as follows:

S= UKM¸ 3T ~

S= Internal deposit stress in pounds per square inch, PSI

K= Calibration constant value provided by the manufacture.

M=Modulus of Elasticity, dynes/cm², of the deposit divided by that of the substrate: M=ED÷ES,

U = Total number of increments spread between the test strip leg tips

T= Deposit average thickness in inches.

 

 

 

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