Properties of Electroless Nickel
The properties of electroless nickel including corrosion resistance are influenced by the type of alloy. This can be a low phosphorous nickel coating, a medium phosphorous nickel coating, a high nickel phosphorous coating or a nickel boron coating.
The table below outlines the various properties and nickel alloy type.
Property / Level of alloy 
High a 
Mid a 
MidLow a 
Low a 
MidLow Bb 
Low Bb 
% Phosphorous 
10 – 13 
7 – 9 
4 – 6 
1 – 3 
– 
– 
% Boron 
– 
– 
– 
– 
3 – 5 
0.2 – 1 
Deposit density Range (g/cm^{3}) 
7.6 – 7.9 
8.0 – 8.2 
8.3 – 8.5 
8.6 – 8.8 
8.25 
8.8 
Plating rate (µ/Hr) 
7.5 – 15 
7.5 – 15 
18 – 30 
11 – 19 
– 
– 
Hardness^{c,f} 
400 – 525 
500 – 600 
625 – 750 
725 – 800 
650 – 750 
600 – 700 
Rockwell C (Rc) Hardness 
41 – 46 
45 – 51 
53 – 59 
57 – 61 
54 – 59 
51 – 56 
Hardness after heat treat^{c} 
850950 
8501000 
8501100 
9001100 
11001200 
500600 
Taber wear index^{e,f} 
22 – 24 
16 – 20 
10 – 14 
7 – 12 
3 – 10 
7 – 9 
Coefficient of thermal expansion^{g} 
8 – 10 
10 – 15 
11 – 14 
12 – 15 
– 
– 
Electrical resistivity^{h} 
75 – 110 
40 – 70 
15 – 45 
10 – 30 
40 – 90 
10 – 20 
Thermal conductivity^{i} 
0.010 
0.012 
0.016 
0.015 
– 

Tensile strength (MPa) 
650900 
8001000 
350600 
200400 
– 
– 
Elongation 
1 – 1.25 
0.5 – 1 
0.5 1 
0.5 – 1.5 
0.2 
– 
Modulus of elasticity (GPa) 
55 – 70 
50 – 65 
45 – 65 
55 – 65 
120 
– 
Melting range^{o}C 
880900 
880980 
11001300 
12501360 
10401080 
13501390 
Coercivity (Oe) 
0 
1 – 8 
10 15 
15 – 80 
– 
– 
Magnetic properties^{f} 
Non 
Slightly 
Magnetic 
Magnetic 
– 
Weakly 
Internal stress^{f} 
Neutral to comp 
Slightly tensile 
Slightly comp 
Slightly tensile 
Tensile 
Step by Step procedure for Electroless Nickel Plating PN: (For Deposit Stress Analyzer System)
Step 1: To remove finger oils, dip the test strip in a soak cleaner solution, water rinse.
Step 2: If a nickel strike is necessary, place the test strip in a Wood’s nickel strike bath.
Step 3: With the test strip negatively charged, plate the test strip for 30 seconds at 0.42 amps.
Step 4: Rinse the test strip in water and rinse in isopropyl alcohol and dry.
Step 5: Weigh a PN: 270NI test strip to the nearest thousandth of a gram and record the weight so the weight of the deposit can be determined later after plating. This value is necessary to calculate the deposit thickness prior to calculating the deposit stress.
Step 6: Place it in the electroless nickel alloy plating bath. Plate the test strip until the test strip leg tips separate at a distance of no more than 20 total units spread on the Deposit Stress Analyzer.
Step 7: Then remove the test strip, rinse it in water and isopropyl alcohol, blot it between a folded paper towel and gently pull it from between the layered paper towel to dry it. This will not alter the test strip leg tip spread distance since its tension memory remains unaffected.
Step 8: Place the plated test strip in the PN: 683 Deposit Stress Analyzer and read and record the total number of increments spread between the test strip leg tips. If the test strip leg tips are not close to an even distance from the zero mark on the scale, bend the test strip with a thumb at the top where suspended from the measuring stand gently to cause the leg tips to hang at a more equal distance from the zero mark.
For example, 2.4 on the left side of zero + 3.1 on the right side of zero = 5.5 which becomes the value for U in the formula S = UKM / 3T.
NOTE: The plating test should be continued until the test strip legs deflect from 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 deposits should not exceed and average thickness of 100 microinches. If the stress is near zero, a reading as low as 1 unit may result.
Step 9: Weigh the test strip and obtain the deposit weight by subtraction.
Step 10: Solve the formula T = Grams of Deposit divided by the multiplication of the Deposit Specific Gravity x 7.74 square centimeters x 2.54 centimeters per inch.
The value of T will be in inches.
K is the calibration value determined by Specialty Testing and Development Company and is marked on each package.
M = the plating deposit modulus of elasticity as PSI (pounds per square inch), divided by 30,000,500 PSI (the nickel test strip material modulus of elasticity).
The deposit value for the electroless nickel alloy coating can be obtained from the Table select the mid range that pertains to the alloy that is being deposited. Note the values on the Table are in GPa.
Step 11: Solve the DSA formula to determine the deposit stress as PSI per above chart.
.
Deposit Thickness Formula For Chemically Applied Deposits:
W
T = ────────────────── = cm where
D (87.53cm²) (2.54cm²/in²)
W = Deposit weight in grams,
D = Deposit specific gravity in grams/cm³= 8.88g/cm³ for pure nickel deposits.
Electroless Nickel
The values for E and M are required to accurately solve the Stoney Formula and the value M is required to solve the Deposit Stress Analyzer Formula.
M = EDeposit ÷ ESubstrate
Frequently, the increase that the Modulus of Elasticity effects on the internal deposit stress of electroless applied alloy coatings is not recognized. Numerous formulas for calculating the internal deposit stress of metallic deposits do not include a correction for the difference of the Modulus of Elasticity between the deposit and the substrate material. In such cases, the calculated result can be far from the actual value. Call the supplier of your electroless nickel alloy plating chemistry for the Modulus of Elasticity value of the deposit.
Note: how necessary it is to use the value for M to determine the actual internal deposit stress value in calculating results for the bent strip method or for the spiral contractometer method. Often the results are calculated without incorporating the correct value of E in these formulas by assuming that electroless nickel deposits have a Modulus of Elasticity similar to that of pure nickel deposits, or they fail to include the value for M in the equations altogether.