This standard specifies the determination method of cathode current efficiency of electroplating solution. This standard is applicable to all kinds of electroplating solution. JB/T 7704.3-1995 Electroplating solution test method cathode current efficiency test JB/T7704.3-1995 Standard download decompression password: www.bzxz.net
This standard specifies the determination method of cathode current efficiency of electroplating solution. This standard is applicable to all kinds of electroplating solution.

Mechanical Industry Standard of the People's Republic of China
Test Methods for Electroplating Solutions
Cathode Current Efficiency Test
1 Subject Content and Scope of Application
This standard specifies the method for determining the cathode current efficiency of electroplating solutions. This standard applies to all types of electroplating solutions.
2 Terminology
2.1 Cathode Current Efficiency
JB/T 7704.3 95
According to Faraday's law, the ratio of the actual mass of the deposited coating to the electrochemical equivalent when a unit of electricity passes through the cathode. Usually expressed as a percentage.
2.2 Coulombmeter
An electrolytic cell that measures the amount of electricity based on the electrochemical action produced according to Faraday's law. 3 Principle of the method
After the plating tank of the electroplating solution to be tested is connected in series with a copper coulometer for electroplating, the mass of the substance actually precipitated on the cathode due to the electrode reaction is first accurately weighed. According to Faraday's law, the amount of electricity passing through the electrode is calculated using the weight coulometer, and then the cathode current efficiency of the solution to be tested in the plating tank is calculated. The weight coulometer used in this method is a copper coulometer. 4 Experimental device, instruments and equipment
4.1 Copper coulometer
4.1.1 Experimental device
The copper coulometer usually uses a glass container as a plating tank, in which three plates are placed. That is, high-purity copper plates or electrolytic copper plates are placed on both sides of the container as anodes. A copper sheet is placed in the middle as a cathode (as shown in Figure 1). 6
Figure 1 Schematic diagram of coulombmeter for measuring current efficiency
1 DC power supply: 2-Amperemeter: 3-Test bath: 4-Copper coulombmeter: 5-Test bath cathode+ 6-Copper coulombmeter cathode: 7-Test bath anode: 8-Copper coulombmeter anode Approved by the Ministry of Machinery Industry on 1995-06-20
1996·0101 Implementation
4.1.2 Test solution
JB/T 7704. 3--- 95
The solutions were prepared with chemically pure reagents. The solution composition is as follows: sulfuric acid (H2SO4*=1.84g/mL) 25 mL/L; copper sulfate (CuSO4·5H2O)
Ethanol (CH.OH))
4.1.3 Test conditions
Temperature: 18~25℃;Www.bzxZ.net
125 g/L;
50mL/L
Cathode current density: 20~200A/m (0.2~2A/dm2): Plating time: 10~30min.
4.2 DC power supply: 0~10A.
4.3 Amperemeter: range 0~10A, 0.5~1 level. 4.4 Analytical balance: range 0~200g, sensitivity 0.0001. 4.5 Anode: Select materials that meet national standards according to the type of plating to be measured. 4.6 Cathode: Select according to the type of plating to be measured.
5 Test steps
5.1 Pour the plating solution to be tested and the copper coulometer solution into their respective plating tanks, and keep the temperature constant according to their process conditions and test conditions. 5.2 Clean the copper anode of the coulometer and the anode of the plating solution to be tested and put them into the two plating tanks respectively. Install the wiring as shown in Figure 1 (two plating tanks are connected in series).
5.3 Clean, blow dry and weigh accurately the cathode of the coulometer and the cathode of the electroplating solution to be tested according to the requirements of pre-plating treatment. 5.4 Place the two cathode pieces in their respective tanks with electricity at the same time, and electroplate according to the process conditions. Take out the two cathode pieces with electricity after the specified time. Clean, blow dry and weigh accurately.
6 Calculation of results
The cathode current efficiency is calculated according to the following formula:
Where:
Cathode current efficiency:
n=mx:186 ×100%
ml—actual weight gain of the cathode sample of the plating solution to be tested·g:-actual weight gain of the cathode sample of the copper coulometer, named mo
Da-—electrochemical equivalent of the precipitated substance on the cathode of the plating solution to be tested·/(A·h); 1.186
electrochemical equivalent of copper·/(A·h).
7 Factors affecting the test results
7.1 Current density
The cathode current density of the copper coulometer should be controlled within the range of 20~200A/m2 (0.2~2A/dm). If the current density is too large, a rough and loose copper plating layer may be produced on the cathode, affecting the measurement results. The cathode current density of the plating solution to be tested should be determined according to the process requirements or the purpose of the test. 7.2 Temperature
During the experiment, the temperature of the copper coulometer should be controlled at 18~25℃. If the temperature is too low or too high, the current efficiency of the copper coulometer will decrease, and the measured amount of electricity will be inaccurate, which will affect the measurement results. The temperature of the plating solution to be tested should be determined according to the electroplating process requirements or the purpose of the test. 7.3 Electroplating solution
7.3.1 When measuring highly corrosive electroplating solutions, the electrolyte may corrode certain cathodes, affecting the measurement results, such as chromium plating solutions. It is not appropriate to use the copper plate directly as the cathode, but the ordinary nickel-plated layer with a density of 5 to 10 um electroplated on the copper plate should be used as the cathode to be tested. 10
JB/T 7704. 3--95
7.3.2 Some electroplating solutions are easy to produce replacement reactions with the cathode copper sheet (such as silver plating solution), which will affect the measurement results. At this time, the cathode test piece must be charged into the tank.
8 Test report
The test report should generally include the following contents: a.
The name and model of the tested plating solution;
This standard number:
Test instruments and equipment:
Test conditions:
Test results:
Test date and test personnel.
Additional instructions:
This standard is proposed by the National Metal and Non-metal Covering Standardization Committee. This standard is under the jurisdiction and drafting of the Wuhan Materials Protection Research Institute of the Ministry of Machinery Industry. The main drafter of this standard is An Zhiling
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