ISO 2179-1986 “Common national standards for Electroplating plating Analysis”

A1 General requirements this method is not applicable to electroplated assemblies because it is difficult to ensure complete removal of the substrate coating.

Note: β-ray backscattering method is more suitable for routine determination of the data layer composition of electrical data assembly.

If an arbitration analysis of the composition of the coating is required, the special sample shall be plated under the same process conditions as the workpiece to be processed and the tin content of the coating shall be determined according to the method in A3.

ISO 2179-1986 “Common national standards for Electroplating plating Analysis”

Preparation of A2 specific sample
A2.1 Hanging plating sample

The 25~30µm tin-lead alloy coating should be plated on an austenite stainless steel plate of about 100mmx80mmx0.5mm. The coating should be easily scraped and peeled off. The specimens that cannot be peeled off should be discarded and prepared again.

Pass.2 Roll plating specimen

2.1 Preparation of de-plating solution, add 50mL of 6%(mass ratio) hydrogen peroxide solution to 50mL of 40%(mass ratio) fluoroboronic acid solution to prepare. A fresh solution should be prepared before use.

2.2 Prepare some copper samples (diameter of about 12mm, length of about 50mm copper rod is more suitable) and the workpiece to be plated together.

2.3 After plating, take a certain number of samples, so that the sum of the quality of the coating is enough to reach about 0.5g, weighing, accurate to 0.00lg. Then immerse in 50mL of de-plating solution (A2.2.1) to remove the coating, clean the label, and collect the label solution in another beaker, dry and weigh the sample again. The tin content was determined according to the method in A3.

ISO 2179-1986 “Common national standards for Electroplating plating Analysis”

Determination of A3 tin
A3.1 Principle

The tin was reduced to divalent tin and determined by iodometry.

Pass.2 range

Tin 10%~90%(mass ratio).

The allowable deviation of tin determination results should be ±0.5%(mass ratio).

Pass.3 reagent

Only analytically pure reagents and fresh distilled water, or boiled and cooled deionized water, can be used during the analysis. A3.3.1 Hydrochloric acid,l)= 1.16-1.18 g/mL.

3.2 Hydrogen peroxide,6%(mass ratio) solution.

3.3Sodium bicarbonate, saturated solution.

A3.3.4 Reduced iron powder, hydrogen reduction, Wuxi.

3.5Starch indicator,10g/L solution.

Mix 1g of soluble starch with water to form a slurry, stir 1 l and add to 100 ml boiling water, and cool for later use.

ISO 2179-1986 “Common national standards for Electroplating plating Analysis”

Standard solution of.3.6 iodate for alloys containing more than 25% tin by mass.

Iodate was dried at 105 ° C, and then 6.0lg of dried iodate was dissolved in 400mL of water containing 1g of sodium hydroxide and 30g of iodide. Diluted to scale in 1000mL volumetric flasks (see A3.8).

1mL of this solution corresponds to 0.010g of tin.

Pass.4 device

All volumetric glassware used shall meet the grade A precision of the corresponding national standards.

A 750mL conical flask with a rubber stopper attached to an appropriate device for the generation and maintenance of an amorous atmosphere, such as a G0cKEL funnel containing saturated sodium bicarbonate solution or a double-ball safety funnel of similar principle. It is also possible to use emotional protective gases (nitrogen, argon or carbon dioxide) in cylinders with pressure reducing valves and pipelines.

ISO 2179-1986 “Common national standards for Electroplating plating Analysis”

5 Preparation of test solution

5.1 Hang plating sample

An analytical sample of 0.5 to 0.8g was weighed to an accuracy of 0.001g and transferred into a 750mL conical flask. 75mL hydrochloric acid (A3.3.1) was added and heated to dissolve it. At the same time, several clear hydrogen peroxide solution (A3.3.2) was added intermittently to promote its dissolution.

5.2 Roll plating specimen

Quantitatively transfer the de-plating solution to a 750mL conical flask. 60mL hydrochloric acid (A3.3.1) was added.

Pass.6 steps

ISO 2179-1986 “Common national standards for Electroplating plating Analysis”

Add enough water to the test solution (A3.5) to make the solution volume 250mL, add 0.5g reduced iron powder (A334), cover and slowly boil until dissolved.

Cap the conical bottle tightly with a rubber stopper with a Getter funnel or double ball safety funnel. Fill the funnel with saturated sodium bicarbonate solution (A3.3.3). Heat the solution to boiling and maintain boiling for more than 30min.

The flask was moved to a heat sink and cooled to below 20 ° C. During the cooling process, it is necessary to replenish saturated sodium bicarbonate solution (A3.3.3) at any time to prevent air inhalation into the bottle.

Remove the rubber stopper and funnel, quickly add 2~3mL starch solution (A3.3.5), clear with iodate standard solution (A3.3.6) until light blue unchanged.

The same amount of reagent was used, but the test solution was not used, according to the same step cycle, and a blank test was performed simultaneously.

ISO 2179-1986 “Common national standards for Electroplating plating Analysis”

Note: It is also possible to use the method of injecting emotional gas. For the specific connection of the device, see Chapter 5 of GB/T10574.1-1989. After adding the test solution (A35), water and reduced iron powder (A33.4) into the flask, plug the rubber stopper and inject the appropriate amount of emotional protective gas.

Heat the solution to boiling, and maintain the boiling for more than 30min; While maintaining the amorous atmosphere, the flask was moved to a radiator and cooled to below 20 ° C. Remove the rubber stopper, quickly add about 20mL of saturated sodium bicarbonate solution (A33.3) and 2 to 3mL of starch solution (A33.5), titrate with potassium iodate standard solution (A33.6) to light blue unchanged.

Pass.7 results show that

The tin content c of the tin-lead coating, expressed as a mass percentage, is calculated as follows:

ISO 2179-1986 “Common national standards for Electroplating plating Analysis”

Where :l’0 Volume of iodate standard solution used to clear the blank solution,mL

v, Volume of one iodate standard solution for clearing the test solution,mL

m0 The mass of the sample taken,g;

m, the mass of tin equivalent to the standard solution of -1mL iodate,g.

Pass.8 Instructions

Calibration of standard solutions of iodate is usually not considered for the accuracy required by this standard. However, if the solution needs to be calibrated, about 0.4g of tin powder with purity of 99.9%(mass ratio) can be weighed, accurate to 0.00lg, and prepared three times according to the method of hanging plating sample (A3.5.1), and measured in parallel.

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