DEPOSIT STRESS ANALYZER
Prevent Deposit Flaking Before It Occurs
A STRESS MEASUREMENT METHOD
APPLICABLE FOR THIN METALLIC COATINGS
ECONOMICAL TO USE
RAPID DETERMINATIONS
ACCURATE RESULTS
PRECALIBRATED TEST STRIPS
SMALL SAMPLE SURFACE AREA
SMALL ELECTROLYTE VOLUME
NEW EASY CALCULATION
Revised date: 12/01/2015
SPECIALTY TESTING & DEVELOPMENT CO.
137 Reynolds Mill Road • YORK, PENNSYLVANIA 17403 • USA
PHONE (717) 428-0186 • FAX (717) 428-0294
www.specialtytest.com
T
1. EQUIPMENT DESCRIPTION
The Deposit Stress Analyzer System is comprised of an economical,
disposable Test Strip, a selection of Plating Cells, and PN 683
Measurement Stand. The Test Strip has a small surface area. It can
be plated in a work tank or in a laboratory setting using an appropriate
Plating Cell. The Cell offers a standard anode to cathode spacing to
ensure uniform current density across the Test Strip legs. After plating,
the Test Strip is placed on a Test Stand to measure in increments
the distance that the Test Strip leg tips have spread. The distance
is included in a formula to calculate the deposit stress in pounds per
square inch. Stress is also determined to be compressive or tensile in
nature. Small permanently mountable plating cells are also available.
See pages 4 and 5.
ST
To determine the thickness of a nickel deposit that weighed .0349 grams,
the calculation would become:
T=
.0349
x .0509 = .000200 inch
8.90
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:
S = UKM÷3T
PN:1194
M=1.714
PN:2042B
M=1.429
PN:270 NI
M=1.000
The measuring device supports the plated test strip over the scale so
the number of scale increments between the tips of the test piece can
be read. The increment reading can then be included in a formula to
calculate the internal deposit stress in pounds per square inch.
where S = pounds per square inch, U = number of increments spread,
T = deposit thickness in inches, K is the strip calibration constant, and
M equals the modulus of elasticity of the deposit ÷
by the modulus of elasticity of the substrate material.
2. TEST PROCEDURE
Each lot of test strips manufactured will respond with slight differences
when used for deposit stress tests. This degree of difference is
determined by the supplier for each lot of test strips manufactured.
The value for K, a calibration factor, is supplied with each lot of test
strips shipped.
Activate using a mild non-alkaline soak cleaner, water rinse, immerse
in 5% sulfuric acid for 15 seconds, and water rinse.
Best results are obtained with a plating set up similar to the photographs
on page 4. Electrical contact should be made at the top of the test strip.
The current density should approximate the value at which work is plated.
The plating test should be continued until the test strip legs deflect from
2-20 units 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 an average
thickness of 150 microinches unless the deposit is soft such as tin. If the
stress is near zero, a reading as low as 1 unit may result.
Where T is in inches,
K=
3TS
UM
Where T is in centimeters,
K=
3TS
2.54 (UM)
For test strip calibration, the value for S is determined by the spiral
contractometer method as a certified value.
3. CALCULATIONS
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:
T=
W
= Inches
D (7.74 cm2) (2.54 cm / inch)
where T = deposit thickness in
inches, W = deposit weight in
grams, D = specific gravity of
the deposited metal in grams
per cubic centimeter and
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÷D)
page 2
4. TABLE OF DENSITY VALUES
(GRAMS/CUBIC CENTIMETER)
Deposited Metal
Density
Cadmium
8.65
Chromium
7.19
Copper
8.96
Gold (Soft)
19.45
Gold (Hard)
17.60
Nickel
8.90
Palladium
12.00
Platinum
21.45
Rhodium
12.44
Ruthenium
12.20
Silver
10.49
Tin
7.30
Zinc
7.13
ST
5. TEST STRIPS
The test strips are made from materials that have spring like properties. Thus, even if the test strip legs are accidentally moved prior
to reading the increments spread, they will return to the correct position so a correct reading can be obtained. They are applicable
for all acidic and alkaline plating chemistries, but certain high cyanide solutions may require an additional resist coating such as a
thin coating of Micro-Shield stop off lacquer diluted 50 percent with acetone and applied with an artist brush.
*PN: 1194 Test Strips are made from Copper-Iron Alloy material 0.002 inch thick for deposit stress determinations between
2,000 – 145,000 psi tensile or compressive stress. Use a Wood’s Ni strike if required for 5 seconds at 50asf, 0.42 amps,
to activate for chemical plating.
*PN: 2042B Test Strips are made from Nickel-Iron Alloy material 0.0015 inch thick for tensile deposit stress determinations
between 500 – 80,000 psi. This material self- activates in most electroless plating baths.
*Pricing (Sold in lots of 25 pcs.):
25-75 pcs.
$6.25 each piece
100-475 pcs. $6.10 each piece
500+ pcs.
$ 5.95 each piece
Test For Nickel (100µ inch deposits)
ASF
AMPERES
TIME
10
.083
12 minutes
30
.25
4 min.
**PN: 270NI This is the most sensitive test strip (pure Nickel 0.0011 inch thick) having particular application for low
internal deposit stress values. It is ideal for nickel, electroless nickel & nickel alloys, chromium, tin, silver, gold, palladium,
platinum, and rhodium. These test strips measure a range of 100-50,000 PSI tensile or compressive stress.
**Pricing (Sold in lots of 25 pcs.):
$ 7.00 each piece
Tensile (Matte)
PN: 1194
PN: 2042 B
PN: 270 NI
Compressive (Bright)
PN: 1194
N/A
PN: 270 NI
PN: 3194 Test Strips are made from Copper 194 material. These strips have no masking material and are sold
in lots of 25 pcs. for $3.95 each. These strips have application for thin organic coatings including resists, and thin ceramic
coating.Simply apply the coating on opposite sides of the test strip legs uniformly and cure or bake. They also have an
application for high cyanide chemistries with the use of Micro-Shield stop-off lacquer that can be brush applied
to define the areas for deposition. Remove this lacquer with acetone prior to measuring the spread.
Internal stress exists as an inherent force within electroplated and chemically applied metallic coatings. This induced stress can be
tensile or compressive in nature, causing the deposit to contract or expand in relation to the base material. High levels of stress in
deposits produce micro-cracking and macro-cracking in the applied layers, and in severe cases produce a lack of deposit adhesion
in the form of blistering, peeling, and flaking, wave-like ripples in electroforms, and accelerated corrosion and wear failure.
TEST STRIP AND ANODE CONSIDERATIONS
Metallic Deposit
Test Strip
Anodes*
Cadmium
1194
Cadmium
Chromium
270NI, 2042B
Lead
Cobalt
1194
Cobalt
Copper
1194
Copper
Gold
270NI, 2042B
Platinum Coated Titanium
Nickel
1194
Nickel
Palladium
1194, 2042B
Platinum Coated Titanium
Platinum
270NI, 2042B
Platinum
Rhodium
270NI, 2042B
Platinum Coated Titanium
Silver
1194
Silver
Tin
1194
Tin
Zinc
1194
Zinc
*Two are required, similar in composition, shape and size. Anodes
2x2x1/8” can be purchased from Kocour Company
page 3
T
ST
DEPOSIT STRESS ANALYZER TEST PROCEDURES FOR TEST STRIPS
(COPPER-IRON ALLOY, IRON-NICKEL ALLOY, AND COLD ROLLED NICKEL MATERIAL)
Any deposited metallic coating can be tested for stress using the DSA Method. Note that this test strip material is applicable
for both tensile and compressive stressed deposits. A Wood’s Nickel Strike may be required for chemically applied coatings.
TEST EQUIPMENT
PN: 800L Plating Test Cell (price includes PN: 404 submersible mini pump).
PN: 3046 Electric Immersion Heater (Note: Heater maintains + 1° F).
GraLab Timer 60 Minutes or equivalent with automatic shut off.
PN: 683 Deposit Stress Analyzer Stand with Measuring Scale.
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 Nickel Anodes 2 x 2 x 1/8 inch (Can be purchased from Kocour Company, 4800 South St. Lewis Avenue, Chicago, IL 60632, 1-773- 847-1111).
TEST SET-UP
1.
Place the anodes in the plating cell anode pockets at the cell ends.
2.
Place the heater in the plating cell (see brochure photo).
3.
Set the pump slide bar to its lowest setting (one notch from OFF). Dampen the suction cups on the submersible pump with
water and fasten the pump 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.
4.
Fill the cell with the plating bath to be evaluated to within one half inch of the top of the cell.
5.
Connect the positive lead from the power supply to the aluminum anode contact provided on the cell.
Connect the red leads on the cell to the respective anodes.
6.
Use the negative lead to fasten a given test strip to the stainless steel support mounted on the cell.
7.
Plug the rectifier into the automatic timer.
8.
Plug the timer, heater and pump into a 120 Volt source.
9.
Heat the plating solution to the operating temperature.
TEST PROCEDURE
1.
Soak clean a sample test strip in a soak cleaner solution at 110 - 120°F for 30 seconds to remove any contamination, then water rinse.
2.
Immerse in a 5% by volume hydrochloric acid solution for 30 seconds at room temperature, then water rinse.
3.
Place the sample test strip in the plating cell by clipping the test strip to the stainless steel cross support so as to have the test
strip centered between the cell walls with the test strip leg tips approximately 1/16th inch from the plating cell bottom. In this
position, the top of the test strip should be approximately 3/16th inch above the support cross bar.
4.
Turn the agitation pump ON and set the timer for the appropriate plating time.
5.
Use a sample test strip to adjust the plating current to the specified amperage. Maintain this rectifier setting for all other test
strips to be plated.
6.
Replace the sample test strip with the one to be evaluated. This test strip should be conditioned as above and exposed to the
plating solution about 30 seconds prior to beginning nickel deposition to assist in surface activation.
7.
Set the timer for the desired plating time and turn on the power supply.
8.
Use the timer to end the plating cycle.
9.
At the end of the plating cycle, remove the test strip from the cell.
10. Rinse the test strip in water, then rinse it in isopropyl alcohol. Lay the test strip on a paper towel and blot it dry with another
paper towel. A paper towel can be folded over and the test strip can be pulled through it.
11. Place the test strip on the measuring stand as near to two minutes as possible, and read and record the total increments spread
as the value for U.
DESPOSIT STRESS EQUATION
1.
For critical certifiable work, average the results of these plated test strips.
2.
Solve the following equation for the internal deposit stress and record this value as pounds/square inch.
S = UKM ÷ 3T
page 4
ST
TEST STRIP MATERIAL: COPPER-IRON ALLOY 0.0020 INCH THICK, PN: 1194
PLATING CONDITIONS FOR NICKEL
Temperature
130
Current Density
30
Plating Current
0.25
Plating Time:
4
Deposit Thickness
100
PLATING:
ºF
Amps/square foot
Amps
Minutes 12 seconds (95% cathode efficiency)
Microinches
DEPOSIT STRESS EQUATION
Solve the equation S = UKM ÷ 3T as follows:
U = Total increments spread of the test strip leg tips on both sides of the zero line.
T = Deposit thickness in inches.
K = The calibration constant value provided by the manufacture.
M = 1.714. The correction factor for the difference in the modulus of elasticity between the deposit and that of the
substrate = EDeposit ÷ ESubstrate = 206900 ÷ 120,690 = 1.714.
S = The internal deposit stress in pounds per square inch.
S=
PSI
2
2
Note: 1 PSI x 703.1 kgm ÷ PSI = kgm .
TEST STRIP MATERIAL: IRON-NICKEL ALLOY 0.00150 INCH THICK, PN: 2042B.
Note that this test strip material is applicable for tensile stressed deposits only. It cannot be used for compressive stressed deposits.
It is self- activating for chemical plating. Any deposited metallic coating can be tested for stress using the DSA Method
PLATING CONDITIONS FOR NICKEL PLATING:
Temperature
130
ºF
Current Density
30
Amps/square foot
Plating Current
0.25
Amps
Plating Time:
3
Minutes 9 seconds (95% cathode efficiency)
Deposit Thickness
75
Microinches
DEPOSIT STRESS EQUATION
Solve the equation S = UKM ÷ 3T as follows:
U = Total increments spread of the test strip leg tips on both sides of the zero line.
T = Deposit thickness in inches.
K = The calibration constant value provided by the manufacture.
M = 1.429. The correction factor for the difference in the modulus of elasticity between the deposit and that of the
substrate = EDeposit ÷ ESubstrate = 206900 ÷ 144830 = 1.429.
S = The internal deposit stress in pounds per square inch.
S=
PSI
TEST STRIP MATERIAL: PURE COLD ROLLED NICKEL 0.0011 INCH THICK, PN: 270NI.
Note that this test strip material is applicable for the determination of tensile and compressive stressed
deposited metallic coatings. It is the most sensitive test strip and is autocatalytic for most chemically applied coatings.
PLATING CONDITIONS FOR NICKEL PLATING:
Temperature
130
ºF
Current Density
30
Amps/square foot
Plating Current
0.25
Amps
Plating Time:
2
Minutes 6 seconds (95% cathode efficiency)
Deposit Thickness Target
50 Microinches
*
If the above test conditions cause the test strip leg tips to spread beyond 24 units due to high internal deposit stress, reduce the
deposition time and the deposit thickness for the test to improve accuracy.
DEPOSIT STRESS EQUATION
Solve the equation S = UKM ÷ 3T as follows:
U = Total increments spread of the test strip leg tips on both sides of the zero line. T =
Deposit thickness in inches.
K = The calibration constant value provided by the manufacture.
M = 1.000, the correction factor for the difference in the modulus of elasticity between the deposit and that of the
substrate = EDeposit ÷ ESubstrate = 206900 ÷ 206900 = 1.000.
S = The internal deposit stress in pounds per square inch.
S=
PSI
page 5
TABLE 1
Values for M to Determine Compressive and Tensile
Deposit Stress for Various Deposited Coatings
Stock Material
E*
Stock Thickness, in
Metal
Cadmium
Chromium
Cobalt
Copper
Gold
Nickel
Platinum
Rhodium
Silver
Tin
Zinc
M**
31,720
248,280
206,897
117,240
74,480
206,900
146,900
289,650
75,860
59,310
82,760
1194
120,690
0.0020
0.263
2.06
1.72
0.971
0.617
1.71
1.22
2.400
0.629
0.491
0.686
2042B
144,830
0.0015
270NI
206,900
0.0011
0.001
Values for M***
0.219
0.153
1.71
1.20
1.43
1.00
0.810
0.567
0.514
0.360
1.43
1.00
1.02
0.710
2.000
1.400
0.524
0.367
0.410
0.287
0.571
0.400
E* modulus of
of elasticity
elasticity of the substrate
substrate material
M** modulus
modulus of
of elasticity
elasticity of
of the
the deposit
deposit
modulus of
of elasticity
elasticity of
of the
the deposit/modulus
deposit/modulus of
of elasticity
elasticity of
of the
the substrate
M*** modulus
stubstrateinin
the modified
modified Deposit
Deposit Stress
StressAnalyzer
Analyzerand
Formula.
electroless
alloy deposits,
the
StoneyFor
Formulas.
For nickel
electroless
check
the
Table
at
www.specialtytest.com.
For
other
alloy
deposits,
obtain
nickel alloy deposits check the Table at www.specialtytest.com. For other the
Modulus
of Elasticity
the supplier.
alloy
deposits,
obtain from
the Modulus
of Elasticity from the supplier.
NOTE: P/N Z042 B is only applicable for tensile stress determinations.
TABLE 2
Electrolyte
Cadmium
Chromium
Copper (cyanide)
Copper (acidic)
Gold (soft)
Gold (hardened)
Nickel
Palladium
Platinum
Rhodium
Silver
Tin(alkaline)
Tin (acidic)
Zinc (acidic)
Zinc (cyanide)
Zinc (alkaline)
Approximate Deposition Rates for Metals
% Efficiency
Amps
ASF*
µ"/Minute
Deposit, µ" **
95
20
80
98
93
40
95
95
85
60
99
60
70
98
98
85
98
85
80
0.33
2.90
0.16
0.33
0.08
0.33
0.33
0.25
0.04
0.08
0.16
0.25
0.42
0.25
0.25
0.25
0.25
40
350
20
40
10
40
40
30
5
10
20
20
50
30
30
30
30
26.1
10
30.8
36.3
26
44.5
31.7
37.5
2.55
4.37
59.4
15
107.8
22.4
30.8
36.2
30.2
24
200
20
100
100
100
75
75
100
200
20
200
200
200
200
200
200
Note: Zinc Cyanide dissolves the resist. Use stop-off lacquer over the resist, then remove with acetone and measure.
*Convert amps per square foot to amps per square decimeter by
dividing the numbers shown above by 10
** Average deposit thickness recommended on test strips.
page 6