ISO 15720:2001 pdf download
ISO 15720:2001 pdf download.Metallic coatings -Porosity tests —Porosity in gold or palladium coatings onmetal substrates by gel-bulk electrography.
k) Set up the equipment and make electrical attachments:
1) apply the calculated current;
2) examine immediately for gross defects;
3) take readings after the prescribed time period:
4) record the results.
7.3 Cleaning
Handle specimens as little as possible and only with tweezers, microscope-lens tissue or clean, soft cotton gloves. Prior to the test, inspect the samples under lOx magnification for evidence of particulate matter. If present, such particles shall be removed by blowing them off with clean, oil-free air. If this is not successful, discard the sample and draw a replacement sample from the batch. Then, clean the samples with solvents or solutions that do not contain chlorinated hydrocarbons, CFCs or other known ozone-destroying compounds. The procedure outlined in the note in 5.2 has been found to give satisfactory results for platings with mild to moderate surface contamination.
NOTE Suggested cleaning procedure.
a) Keep individual contacts separated it there is a possibility of damaging the measurement areas during the various cleaning steps.
b) Clean samples for 5 mm in an ultrasonic cleaner which contains a hot (65 C to 85 °C) 2 % aqueous solution of a mildly alkaline (pH 7.5 to pH 10) detergent.
C) After ultrasonic cleaning, rinse samples under warm running tap water for at least 5 s.
d) Rinse samples ultrasonically for 2 mm in fresh deionized water to remove the last detergent residues.
e) Immerse in fresh methanol or isopropanol and ultrasonically agitate’ for at least 30 s in order to remove the water from the samples.
f) Remove and dry samples until the alcohol has completely evaporated. If an air blast is used for drying, the air shall be oil- free, clean and dry.
g> Do not touch measurement area of the samples with bare fingers after deanirig.
h) Re-inspect samples (under xlO magnification) for particulate matter on the surface. If particulates are found, repeat the cleaning steps. Surface cleanliness is extremely important: contaminants, such as plating salts, organic films and metal flakes, may give erroneous indications of defects and are unacceptable.
7.4 Electrographlc method
Secure the specimens to be tested to gold or platinum lead wires and suspend in the cell so that their measurement areas (see B.3) can be easily seen through the wall of the test vessel (4.1). Place the specimens 13 mm ± 2 mm from the cathode.
NOTE I For longitudinal-shaped contacts, such as pins or posts, where the alternative cell design is used (see Figure 2) the bottom ends or tps of the contacts shall be at a distance from the cathode that is at least 1,5 times their maximum length in the gel solution. The area of the cathode along the bottom of the cell should be not less than the total specimen area in the solution and can be up to twice as large. It the cathode area is too small there will be a risk of excessive hydrogen bubble formation.
The composite test gel solution is prepared from the gel solution (see 5.2) and an indicator and test solution chosen from Table 1. The composite contains by volume, 94,6 % gel solution, 3,4 % test solution and 2 % indicator. It is prepared by melting the gelatin solution at 59 °C ± 1 °C whilst gently stirring, removing from the heat and adding, while stirring, the premixed test solution and then the indicator. Stirring shall be continued for 2 mm to 3 mm in order to thoroughly mix all the components. For consistency, consider the lifespan of the composite gel solution to be 2 h. Testing of the samples shall be accomplished within this time period.
Pour the composite test gel solution into the test vessel, taking care not to introduce bubbles of air into the solution. Allow the gel to solidify.
NOTE 2 It is good pracbce to include with the sample a control specimen that is known to be porous (such as would be produced by scratching the coating to expose substrate). If the control specimen fails to produce a dense opaque pore indication the test results must be discounted and the test repeated using fresh prepared reagents.
