JB/T 7704.4-1995 Test methods for electroplating solutions - Dispersibility test
Some standard content:
Mechanical Industry Standard of the People's Republic of China
Test Methods for Electroplating Solutions
Dispersion Power Test
1 Subject Content and Scope of Application
This standard specifies the test method for the dispersion power of electroplating solutions. This standard is applicable to all types of electroplating solutions.
2 Terminology
2.1 Dispersion Power
JB/F 7704. 4- 95
Under certain conditions, the ability of the plating solution to make the coating distribution on the electrode (usually the cathode) more uniform than the initial current distribution. 2.2 Insoluble Anode (Inert Anode)
Under the process conditions of electrolysis, an anode that does not produce an anodic dissolution reaction in the electrolyte. 2.3 Haring Cell
A rectangular plating cell for non-conductive materials. The main electrode and the auxiliary electrode are appropriately arranged to enable the estimation of the dispersion power or the degree of electrode polarization and the potential between the two electrodes.
2.4 Sponge-like coating
Loose and porous sponge-like deposits that are not firmly bonded to the base material. 3 Test method
3.1 Near and far cathode method
3.1.1 Principle of the method
The near and far cathode method is usually carried out in a Haring cell, as shown in Figure 1. Two cathodes of the same area are placed at different distances from the anode (the two distances are in a simple integer ratio). After a certain period of electroplating, the cathode test pieces are taken out. The weight of the coating on the near and far cathodes is weighed, and the dispersion capacity is calculated according to formula (1):
K--(m/m2)
K+(m:/m2)
Where: T—
Dispersion capacity:
-The ratio of the distance between the near and far cathodes and the anode;-The weight gain of the near cathode:
m2-The weight gain of the far cathode+g.
X 100%
The dispersion capacity value calculated by formula (1) is between -100% and +100%. The larger the value, the better the dispersion capacity. Approved by the Ministry of Machinery Industry on June 20, 1995
(1
1996-01-01 Implementation
3.1. 2
JB/T 7704. 4- 95
Figure 1 Dispersion capacity measurement by far and near cathode method
1-DC power supply: 2-Ammeter: 3-Haring trough: 4, 5 far, near cathode, 6-anode test instruments and equipment
DC power supply: 0~10A;
Ammeter: range 0~10A, 0.5 level~1 level;Haring trough: inner cavity size: 150mm×50mm×70mm;Anode: mesh or porous soluble or insoluble anode;Cathode: iron or copper sheet with insulation on the back
Folding balance: range 0~200g+sensitivity 0.0001g. 3.1.3Test steps
After cleaning the cathode test piece according to the requirements of electroplating pretreatment, apply insulating coating on the back, such as acrylic varnish. At 105~3. 1. 3. 1bZxz.net
Dry and cool at 110C, mark the words "far" and "near", and weigh. 3.1.3.2 Clean the anode and put it into the Haring tank, pour in the plating solution to be tested, keep the temperature constant according to the plating solution process conditions, and install the wiring according to Figure 1. 3.1.3.3 Charge the two cathodes into the tank at the same time, and electroplate according to the plating solution process conditions. Generally, electroplate for 30 minutes, then take them out, rinse them, dry them, cool them to room temperature, and weigh them. Calculate the weight gain of the far and near cathodes, and calculate the dispersion capacity according to formula (1). 3.2 Bent cathode method
3.2.1 Principle of method
The dispersion capacity measured by the bent oil cathode method is shown in Figure 2. Bend the cathode into six equal parts as shown in Figure 2, electroplate it, and then measure the coating thickness in the central part of each plane A, B, D, and E. According to the ratio of the coating thickness of each surface B, D, and E to that of the surface A, that is, B/A, D/A, and E/A, use formula (2) to calculate the dispersion capacity:
T = (B/A) + (DI/A) +(E/A2 × 100% 3
The dispersion ability value determined by this method is in the range of (0～~100)%. The larger the value, the better the dispersion ability of the plating solution. 3.2.2 Test instruments and equipment
DC power supply: 0~10A;
Amperemeter: range 0~10A, level 1;
Test tank: inner cavity size 160mm×120mm×160mm; anode: anode material that meets national standards, size 150mm×50mm×5mm; cathode: the length of each side of the curved cathode is 29mm, the thickness is 0.2~0.5mm, and the back is not insulated; thickness gauge: select a suitable thickness gauge according to the type of coating (the measurement error is less than 10%). **+(2)
3.2.3 Test steps
JB/T 7704.4—95
Figure 2 Bent cathode method for measuring dispersion ability
1 DC power supply: 2-ammeter + 3-plating tank: 4-cathode: 5-electrode x
3.2.3.1 Measure 2.5L of the plating solution to be tested in the test tank, keep the temperature constant according to the plating process conditions, clean the bent cathode and anode according to the requirements of pre-plating treatment, and put them in the test tank together. 3.2.3.2 Connect the power supply and adjust to the required current density for electroplating. Generally, when the current density is 50~~100A/m2 (0.5~~1A/dm2), electroplating is 20min; when it is 200A/m (2A/dm2), electroplating is 15min; when it is 300-500A/m (3--5A/dm), electroplating is 10min. Other current densities and electroplating times depend on the properties of the plating solution. 3.2.3.3 Take out the bent cathode, wash, dry and cool. Measure the coating thickness at the center of each surface A, BD, and E respectively. Calculate the dispersion capacity using formula (2).
3.3 Hall trough sample method
3.3.1 Principle of the method
The device for measuring the dispersion capacity using the Hall trough sample method is shown in Figure 3. During the test, the current intensity is generally selected within the range of 0.5~3A. Some plating solutions, such as chromium plating solutions, can be increased to 5~10A. The test time depends on the solution conditions and is generally 10~~15min. After the test, the cathode sample is divided into 8 parts according to Figure 4, and then the thickness of the coating at the center of squares 1 to 8 is measured. 3, 32, and the dispersion capacity is calculated using formula (3):
X 100%
Where: 3, -The coating thickness at the center of a square in squares 2 to 8·umα——The coating thickness at the center of square 1, μm; T
——The dispersion capacity of a corresponding square.
Drawing a thickness distribution curve with the grid number and the thickness of the center of the grid can qualitatively evaluate the dispersibility of the plating solution. The arithmetic mean of the dispersibility of grids 2 to 8 or only grid No. 5 can be used as a representative to compare the dispersibility of the key solution. The dispersibility value measured by this method is between (0 and 100)%. The larger the value, the better the dispersibility. 14
3.3.2 Test instruments and equipment
JB/T 7704. 4-95
Figure 3 Hall slot sample method for measuring dispersibility
1-DC power supply? 2 Amperemeter: 3 Hall slot￥4 Cathode; 5-Anode liquid surface
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Near end
a. DC power supply: 010A:
Figure 4:
Hall slot cathode sample
b. Amperemeter: Range 0～10A, 0.5～1 level: Hall cell: 250mL. Hall cell;
Remote
Anode: Meet the national standard for electroplating anodes, size 64mm×70mm. If an easily passivated anode is used, it should be made into a corrugated shape. Its geometric surface thickness does not exceed 5mm; e.
Cathode: Use a polished iron or copper sheet of 100mm×70mm, thickness 0.2～1mm; Thickness gauge: Choose a suitable thickness gauge according to different plating types (measurement error is less than 10%). 3.3.3 Test steps
3.3.3.1 Pour the solution to be tested into the Hall cell, and insert the cleaned anode plate against the wall of the cell. 3.3.3.2 Install the wiring as shown in Figure 3. And keep the plating solution constant temperature according to the process conditions. 3.3.3.3 Place the cathode that meets the requirements of electroplating pre-treatment close to the tank wall and carry out electroplating by controlling the current intensity and electroplating time according to the process conditions of the plating solution.
3.3.3.4 Disconnect the power supply, take out the cathode test piece, wash it, dry it, and draw a sample diagram according to Figure 4. Measure the thickness of the coating at the center of squares 1 to 8. Use formula (3) to calculate the dispersion capacity.
4 Factors affecting the test results
4.1 K value
In the far-cathode and near-cathode methods, the selection of K value directly affects the determination of dispersion capacity. There are generally three types of K values: 2.3.5. The K value should be selected according to the properties of the plating solution. If the K value is 5, then when some plating solutions are tested at a higher current density, a sponge-like, dendritic or muddy coating will appear at the bottom of the near-cathode surface.Causes a large measurement error. Therefore, it is necessary to select a suitable K value within the working current density range. The working current density range is wider and the plating solution with better dispersibility can select a larger K value, otherwise, a smaller K value should be selected. 15
4.2 Cathode
JB/T 7704. 4-95
No matter which method is used to measure the dispersibility, the cathode must be cleaned according to the requirements of pre-plating treatment to avoid thickness and weight measurement errors. In the far and near cathode method, the back of the cathode must also be insulated. If the insulation of the back of the cathode is not good, the uninsulated back of the cathode may be coated during electroplating, which directly affects the test results. On the other hand. When selecting the cathode material, attention should be paid to the chemical corrosion of certain plating solutions on the cathode, such as the corrosion of chromium plating solution on copper sheets. If necessary, a corrosion-resistant intermediate coating should be applied to the cathode. Such as nickel, and pay attention to the charged tank. 4.3 Anode
The anode must comply with the provisions of the national standard for electric bonding anode. In the far and near cathode method, the anode is often a drilled or mesh anode. To facilitate solution convection, and increase the anode area to reduce the impact of anode polarization on the test results. 4.4 Electrical contact
Electrical contact must be good, so that the measurement results have good reproducibility. Otherwise, it will cause large measurement errors. 5 Test report
The test report should generally include the following: a.
Name and model of the tested plating solution;
This standard number and the test method used;
Test instruments and equipment;
Test conditions:
Test results and calculation formulas:
Test date and test personnel.
Additional instructions:
This standard was proposed by the National Metal and Non-metal Covering Standardization Committee. This standard was drafted by the Wuhan Materials Protection Research Institute of the Ministry of Machinery Industry. The main drafter of this standard is Jiang Xinhua.
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