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IPC-TM-650 TEST METHODS MANUAL
1 Scope
This test method provides a procedure for testing
the porosity of gold electroplated from an alkaline (cyanide),
acid, or neutral gold plating solution on a nickel substrate in
contact with the gold deposit.
2 Applicable Documents
None
3 Materials and Equipment
3.1 Materials
Acetone, Sodium Nitrate, Reagent GD.
(NaNO
3
), Sodium Carbonate, Anhydrous, Reagent GD.
(Na
2
CO
3
), Dimethylglyoxime, Denatured Ethyl Alcohol No. 3A,
Reagent GD. (C
2
H
5
OH), Photographic Paper with Silver
Halide removed. (Kodabromide, glossy finish, single wt. pho-
tographic paper (fixed before use), Ammonium Hydroxide,
Reagent GD. (NH
4
OH)
3.2 Equipment
3.2.1
DC power supply to 0 amp to 1 amp. DC minimum, 0
volts to 10 volts
3.2.2
DC Milliammeter, 0 mA to 100 mA
3.2.3
Electrographic Clamp-Press
4 Equipment/Apparatus
None
5 Procedure
5.1 Solution Make Up
5.1.1 Electrolyte
Concentration: NaNO
3
1% (wt.) Na
2
CO
3
,
Anhydr. 4% (wt.) Distilled water balance by wt. Preparation
of 500 g (Vol. of 485 ± 10 ml.) of solution
5.1.1.1
Obtain the tare weight of 600-ml glass beaker.
5.1.1.2
Add 400 ml of distilled water to beaker.
5.1.1.3
Using agitation and, if necessary, heating to 48.9°C,
dissolve the following in the water:
Sodium nitrate 5 g
Sodium carbonate 20 g
5.1.1.4
After salts are dissolved, add distilled water until the
net weight of the solution is 500 g.
5.1.1.5
Cool the solution to room temperature before use.
5.2 Indicator Solution
The solution is a concentration of
dimethylglyoxime 1% (wt.) denatured ethyl alcohol No. 3A
Balance.
Perform the preparation of 300 g (vol. of 380 ± 10 ml.) of
solution as explained in 5.2.1 through 5.2.4.
5.2.1
Obtain the tare weight of 400-ml glass beaker.
5.2.2
Add 275 ml denatured ethyl alcohol to the beaker.
5.2.3
Using agitation only (do not heat), dissolve 3 g of dim-
ethylglyoxime in the alcohol.
5.2.4
After all additions are dissolved, add denatured ethyl
alcohol until the net weight of the solution is 300 g.
5.3 Electrographic Test
5.3.1 Cleaning Procedure
5.3.1.1
Using a cloth, wash the contact area with alconox
solution.
5.3.1.2
Rinse the contact area in tap water.
5.3.1.3
Rinse the contact area in deionized water.
5.3.1.4
Rinse the contact area with acetone and air dry.
5.4
Cut a piece of silver halide-free photographic paper to a
size slightly larger than the area of the sample or part of the
sample being tested. The dimensions of the photographic
paper should not exceed the dimension of that part of the
sample being porosity tested by more than 0.79375 mm in
any one direction.
5.5
Wet the photographic paper, cut in 5.2 with the electro-
lyte solution prepared in 5.1.1. The photographic paper is
immersed for 30 minutes or more in the electrolyte.
The Institute for Interconnecting and Packaging Electronic Circuits
2215 Sanders Road Northbrook, IL 60062-6135
IPC-TM-650
TEST METHODS MANUAL
Number
2.3.24.1
Subject
Porosity Testing of Gold Electrodeposited on a Nickel
Plated Copper Substrate Electrographic Method
Date
10/85
Revision
Originating Task Group
N/A
Material in this Test Methods Manual was voluntarily established by Technical Committees of the IPC. This material is advisory only
and its use or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of this
material. Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement.
Equipment referenced is for the convenience of the user and does not imply endorsement by the IPC.
Page 1 of 3 After saturating the photographic paper with electrolyte, press
the paper between two paper towels to ensure any excess
electrolyte is removed from the photographic paper.
5.6
Assemble the sample being tested for porosity and the
photographic paper of 5.5 in the electrographic clamp-press
as explained in 5.6.1 through 5.6.6.
5.6.1
Place a piece of Teflon or equivalent insulating mate-
rial on the platform of the compression spring and piston
device on the clamp-press.
5.6.2
Place the back of the sample or area of sample being
tested on top of and in contact with the Teflon.
5.6.3
Place the silver halide-free photographic paper satu-
rated with electrolyte in 5.5 on top of and in contact with the
face of the sample or area of the sample being tested. The
emulsion side of the paper should be in contact with the test
sample.
5.6.4
Place a piece of pure gold or gold-clad copper on top
of the photographic paper so the gold surface is in contact
with the photographic paper.
The gold or gold-clad material placed on the photographic
paper is to have the same maximum dimensions as that part
of the sample being porosity tested. The minimum dimensions
of the gold or gold-clad material is to be not more than
0.79375 mm shorter than the dimensions of the area being
tested in any one direction. Attach a lead wire to the gold or
gold-clad material in order to make electrical contact.
5.6.5
Place a piece of Teflon or equivalent insulating mate-
rial on the back of the gold or gold-clad material.
5.6.6
Lower the screw of the clamping and screw the
device until the pressure end of the screw is just in contact
with the back of the Teflon and holds the assembly in place.
Do not apply force at this time. See 5.11 for a schematic dia-
gram of assembly.
5.7
Compress the spring of the clamp-press by tightening
the screw device until a pressure is exerted on the assembly
as in 5.6.6.
5.8
Connect a DC power source so the positive (+) voltage
contacts the sample being tested and the negative (-) voltage
is connected to the lead of the gold or gold-clad material of
5.6.6. Apply a current, such that the current density is 250 mA
± 50 mA per square inch of surface in contact with the pho-
tographic paper. Applied voltage should not exceed 10 volts.
If the current density of 250 ± 50 mA/sq. in. cannot be
obtained at 10 volts, then the time of current flow should be
increased while holding the potential at 10 volts. The
increased time of current flow can be calculated by the follow-
ing formula.
Time of current flow (sec) =
250 mA
/sq. in. of surface in contact with paper
Current density in mA
/sq. in. at 10 volts
x 60 sec
The time of the current flow should be 60 ± 1 sec.
5.9
Unclamp the assembly and remove the silver halide-free
photographic paper.
5.10
Apply one to two drops of the indiicator solution from
5.2. to the photographic paper.
5.11
Develop the photographic paper containing indicator
solution by holding the paper over an ammonium hydroxide
solution.
5.12
Dry the photographic paper to which indicator solution
was added and read the test results.
5.13
Observe the porosity test schematic, as shown in Fig-
ure 1.
5.14 Test Results
5.15
Nickel exposure through the gold will show up on the
indicating photographic paper as a red stain. Copper expo-
sure will show up as green stains. This exposure is caused by
pores, cracking, or unplated areas. These stains should be
examined under 10X min, 15X max.
5.15.1 Pores
Pores will show up as fine dots.
5.15.2 Cracking
Cracks will show up as continuous fine
lines.
5.15.3 Unplated Areas
Unplated areas will show up as
large blots or red lines.
IPC-TM-650
Number
2.3.24.1
Subject
Porosity Testing of Gold Electrodeposited on a Nickel Plated Copper
Substrate Electrographic Method
Date
10/85
Revision
Page 2 of 3 IPC-23241-1
Figure 1
Porosity Test Schematic
mA
VM
Power Supply
o-1 a DC
o-10 V
-
+
-
+
Teflon®
Gold Clad Plate
Photographic Paper, Silver Halide Free
Sample Under Test
Teflon®
IPC-TM-650
Number
2.3.24.1
Subject
Porosity Testing of Gold Electrodeposited on a Nickel Plated Copper
Substrate Electrographic Method
Date
10/85
Revision
Page 3 of 3