A silver-silicon contact resistance test screen plate for silicon-based photovoltaic paste and a test method thereof

Abstract

The application discloses a silver-silicon contact resistance test screen plate for silicon-based photovoltaic slurry and a test method thereof. The test screen plate comprises a silicon wafer, and a cross line is marked in the middle of the front surface of the silicon wafer to divide the front surface into four printing areas with the same area. The four printing areas are divided into two groups with two opposite angles as a group. Two printing areas in the first group are arranged into two rows of vertical gate lines according to the opposite angles, and two printing areas in the second group are arranged into two rows of horizontal gate lines according to the opposite angles. Each row of vertical gate lines and horizontal gate lines comprises six gate lines with the same size, and the gate lines are parallel to each other. The application provides a screen plate design and a test method for contact resistance test, so that the performance of the material can be better evaluated, and the conversion efficiency of the battery piece is effectively improved. In addition, the screen plate and the test method can satisfy that two different silver electrodes are printed on the same silicon wafer, the difference in bulk resistance between different silicon wafers is effectively reduced, and the accuracy of the contact resistance test result is ensured.

Description

Technical Field

[0001] The invention discloses a silver-silicon contact resistance test screen for silicon-based photovoltaic slurry and a test method thereof. Background Art

[0002] Optimizing solar cell electrodes is an important means to improve cell performance and reduce production costs. The silver paste on the front of the cell is usually composed of high-purity silver powder, glass system, organic system, etc. Among them, silver powder is a conductive functional phase, and its quality will directly affect the bulk resistance and contact resistance of the electrode material, and thus affect the photoelectric conversion efficiency; the glass system is a high-temperature bonding phase, which plays a decisive role in the sintering of silver powder and the formation of silver-silicon ohmic contact; the organic system, as a key component of the silver powder and glass system, has a significant impact on printing performance and printing quality. Therefore, by testing the contact resistance between silver and silicon in the silver paste, the feasibility of silver powder and glass powder materials can be effectively evaluated, thereby more accurately screening materials.

[0003] Currently, the commonly used contact resistance testing methods are TLM and Core Scan, both of which can measure contact resistance. However, due to differences between silicon wafer sources, if the contact resistance between silver and silicon is evaluated on two different silicon wafers, the accuracy of the measurement results will be uncertain. Therefore, to improve test accuracy, reduce experimental costs, and meet testing requirements, a method is needed to measure the contact resistance of different silver electrodes on the same wafer source.

[0004] Furthermore, while numerous existing cell contact resistance testers exist, their high cost, fragility of the probe array, and high maintenance costs restrict their effective use in the process of screening raw materials and preparing silver paste. Furthermore, some contact resistance test methods, when pressing the silver electrode, tend to deviate from the silver electrode due to the thinness of the cell's secondary grid lines, resulting in a small contact area. This can lead to deviations from the silver electrode during operation, causing the test results to deviate from the theoretical value and compromising the selection of raw materials. Summary of the Invention

[0005] In response to the aforementioned technical problems in the prior art, the present invention aims to provide a silver-silicon contact resistance test screen and testing method for silicon-based photovoltaic pastes. This invention provides a screen design and testing method for contact resistance testing, enabling better evaluation of material performance and effectively improving cell conversion efficiency. Furthermore, this screen and testing method enable the printing of two different silver electrodes on the same silicon wafer, effectively reducing the difference in bulk resistance between wafers and ensuring the accuracy of contact resistance test results.

[0006] The silver-silicon contact resistance test screen for silicon-based photovoltaic paste is characterized in that the test screen includes a silicon wafer, and a cross line is marked in the middle of the front of the silicon wafer to divide it into four printing areas of equal area. The four printing areas are divided into two groups with two diagonals as a group. The first group of two printing areas have two rows of vertical grid lines arranged diagonally, and the second group of two direction areas have two rows of horizontal grid lines arranged diagonally. Each row of vertical grid lines and horizontal grid lines includes 6 grid lines of the same size, and the grid lines are parallel to each other.

[0007] The silver-silicon contact resistance test screen for silicon-based photovoltaic paste is characterized in that the length of each grid line is 15-25 mm, preferably 20 mm.

[0008] The silver-silicon contact resistance test screen for silicon-based photovoltaic slurry is characterized in that the widths of the vertical grid lines in each row are the same, and the width of the grid lines is 0.3-0.5 mm.

[0009] The silver-silicon contact resistance test screen for silicon-based photovoltaic paste is characterized in that each row of vertical grid lines or horizontal grid lines is arranged in the central area of ​​the corresponding printing area.

[0010] The silver-silicon contact resistance test screen for silicon-based photovoltaic paste is characterized in that the spacing between two adjacent vertical grid lines in each row is distributed from dense to sparse from left to right; at the same time, the spacing between two adjacent horizontal grid lines in each row is distributed from dense to sparse from top to bottom.

[0011] The silver-silicon contact resistance test screen for silicon-based photovoltaic slurry is characterized in that the intervals between two adjacent grid lines in each row of 6 grid lines are 0.2mm, 0.4mm, 0.8mm, 1.6mm, and 3.2mm respectively.

[0012] The silver-silicon contact resistance test screen for silicon-based photovoltaic slurry is characterized in that the area of ​​the silicon wafer is 166mm*166mm.

[0013] The resistance testing method of the silver-silicon contact resistance test screen of the silicon-based photovoltaic paste is characterized in that it includes the following steps: marking a cross line in the middle of the front of the silicon wafer to divide it into four printing areas of equal area, placing the silicon wafer forward into the printing press to print silver electrodes, first placing the first silver paste and printing two rows of vertical grid lines diagonally in the first group of two printing areas of the silicon wafer, rotating the silicon wafer 90° after drying, then placing the second silver paste and printing two rows of horizontal grid lines diagonally in the second group of two printing areas of the silicon wafer, and placing the silicon wafers into a chain drying furnace for sintering after drying. After sintering, take out the silicon wafer for contact resistance testing. The contact resistance test is performed by using two electric touch pens on a DC bridge device to contact two adjacent grid lines of each row of vertical grid lines or horizontal grid lines on the silicon wafer. The resistance test result is displayed on the display screen of the DC bridge device, and the detection is completed.

[0014] The present invention discloses a design and testing method for a silver-silicon contact resistance test screen for silicon-based photovoltaic paste. The screen can print multiple pastes in batches during the printing process and use a bridge device to test the size of the contact resistance between silver and silicon.

[0015] The beneficial effects achieved by the present invention are:

[0016] The present invention optimizes the length and width of the gate lines, as well as the spacing between the gate lines, during contact resistance testing, so that the size of the contact resistance can be more accurately described in the test results. At the same time, the designed test method can simultaneously print two different slurries on the same silicon wafer for testing, reducing the complexity of material evaluation and further reducing experimental costs while meeting the requirements of material evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of the vertical grid line design of the screen in Example 1 of the present application;

[0018] Figure 2 This is a schematic diagram of the structure of the arrangement of vertical grid lines and horizontal grid lines on the screen of this application;

[0019] Figure 3 This is the standard curve drawn according to the test results in Table 1 in Example 1 of the present application;

[0020] Figure 4 This is the standard curve drawn according to the test results in Table 2 in Example 1 of the present application;

[0021] Figure 5 This is the standard curve drawn according to the test results in Table 3 in Example 1 of the present application;

[0022] Figure 6 This is the standard curve drawn according to the test results in Table 4 in Example 2 of the present application;

[0023] Figure 7 This is the standard curve drawn according to the test results in Table 5 in Control Example 1 of this application. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0025] Example 1:

[0026] The screen designed in this embodiment 1 is described as follows Figure 1 As shown, the screen includes a silicon wafer, and a cross line is marked in the middle of the front side of the silicon wafer to divide it into four printing areas of equal area. The four printing areas are divided into two groups with two diagonal corners as a group. The two printing areas in the first group are arranged with two rows of vertical grid lines diagonally, and the two directional areas in the second group are arranged with two rows of horizontal grid lines diagonally.

[0027] The two rows of vertical lines comprise a total of 12 lines, wherein the lines are parallel to each other, with each row consisting of 6 lines, and the two rows of lines are designed to be opposite to each other. Similarly, the two rows of horizontal lines also comprise a total of 12 lines, wherein the lines are parallel to each other, with each row consisting of 6 lines, and the two rows of lines are designed to be opposite to each other.

[0028] In this embodiment 1, two rows of vertical grid lines and two rows of horizontal grid lines are respectively located in the middle position of the four printing areas, and their lengths are both 20 mm. The intervals between two adjacent grid lines in each row of 6 grid lines are 0.2 mm, 0.4 mm, 0.8 mm, 1.6 mm, and 3.2 mm from dense to sparse.

[0029] Furthermore, the size of the cell for the screen matching test is 166*166 mm.

[0030] The screen printing method and contact resistance testing method of Example 1 of the present invention are as follows:

[0031] First, load the screen into the printing machine, and place the silicon wafer forward into the printer to print the silver electrode. Mark the middle of the front of the silicon wafer with a cross line to divide it into four printing areas of equal area. Place the silicon wafer forward into the printer to print the silver electrode. First, put the first silver paste and print two rows of vertical grid lines diagonally in the first two printing areas of the silicon wafer. After drying, rotate the silicon wafer 90 degrees and then put the second silver paste. The printing status is as follows Figure 2 As shown, two rows of horizontal grid lines are printed diagonally in the second two printing areas of the silicon wafer. After drying, the silicon wafers are uniformly placed in a chain drying furnace for sintering (rapid sintering at 750°C for 1 minute). After sintering, the silicon wafers are taken out for contact resistance testing. The contact resistance test is carried out by using two contact pens on a DC bridge device to contact two adjacent grid lines of each row of vertical grid lines or horizontal grid lines on the silicon wafer, read out the data on the display screen and record it, and stipulate that 5 points are taken on each of the two grid lines, one to one corresponding.

[0032] The mass percentage ratio of the first silver paste is: organic vehicle 6.5%, glass powder 2.1%, silver powder 89.5%, and other additives 1.9%.

[0033] The mass percentage ratio of the second silver paste is: organic vehicle 6.5%, glass powder 2.3%, silver powder 89.5%, and other additives 1.7%.

[0034] Preparation of organic carrier: 10% ethyl cellulose, 5% cellulose acetate, 6% polyamide resin, 5% tributyl citrate, 7% dimethyl phthalate, 30% butyl carbitol, 25% butyl carbitol acetate, and 12% terpineol are stirred and dissolved at 80°C for 2 hours to obtain a uniform organic carrier.

[0035] Preparation of glass powder: 38% PbO, 11% BiO, 7% BO, 5% CaO, 8% SiO, 6% ZnO, 2% TiO, 3% AlO, 1.5% NiO, 2.5% CuO, 7% MnO, 5% LiO, 2% LiF, 1% PbF, 1% WO. Prepare the glass powder and melt it at 1200°C for 4 hours. Pour the molten glass powder into deionized water for quenching, and then ball mill and dry it to obtain micron-sized glass powder.

[0036] BYK110 was used as other additives.

[0037] In Example 1, the first silver paste was used to print two diagonally opposite rows of vertical grid lines in the first two printing areas of the silicon wafer. After drying and sintering, a contact resistance test was performed. The contact resistance test involved contacting two adjacent grid lines in each row of vertical grid lines on the silicon wafer with two styluses on a DC bridge device. The data on the display was read and recorded. Five points were taken on each of the two grid lines, and the average contact resistance was calculated.

[0038] The first silver paste printed electrode was tested for contact resistance. The test results of the adjacent spacing of the vertical grid lines in the first printing area are shown in Table 1, and the test results of the adjacent spacing of the vertical grid lines in the second printing area are shown in Table 2. A standard curve was drawn with the spacing distance L between adjacent grid lines as the horizontal axis and the test resistance data R as the vertical axis. The standard curve drawn based on the test results in Table 1 is shown in Figure 2. Figure 3 As shown in Table 2, the standard curve drawn according to the test results is as follows Figure 4 shown.

[0039]

[0040]

[0041] It can be seen from the test results in Table 1-2 that the contact resistance test results of the screen printed with the same silver paste are relatively stable.

[0042] The second silver paste used in Example 1 was used to print two diagonally opposite rows of horizontal grid lines in the second set of two printing areas on the silicon wafer. After drying and sintering, a contact resistance test was performed. The contact resistance test involved contacting two adjacent grid lines in each row of horizontal grid lines on the silicon wafer with two styluses on a DC bridge device. The data on the display was read and recorded. Five points were taken on each of the two grid lines, and the average contact resistance was calculated.

[0043] The second silver paste printed electrode was tested for contact resistance. The test results of the adjacent spacing of the horizontal grid lines in the first printing area are shown in Table 3. A standard curve was drawn with the spacing distance L between adjacent grid lines as the horizontal coordinate and the test resistance data R as the vertical coordinate. The standard curve drawn according to the test results in Table 3 is shown in Table 3. Figure 5 shown.

[0044]

[0045] From the comparison of the test results in Table 1-2 and Table 3, it can be seen that there are certain differences in the contact resistance test results of the screens printed with different types of silver pastes.

[0046] The above is the specific data of contact resistance obtained by the designed screen printing grid line test. As shown in Table 1-3 and Figure 3-5 The figure shows the stability evaluation data of the same slurry and the contact resistance obtained by printing different slurries on the same silicon wafer.

[0047] From Example 1, it can be seen that the contact resistance values ​​obtained from repeated tests of the same slurry are stable. Figure 3-4 The fitting degree of the midline trend line can reach 99.74%~99.82%, indicating that the contact resistance value obtained by the designed screen test is relatively stable. In addition, by testing the gate electrode printed with different pastes on the same silicon wafer, the contact resistance values ​​obtained by the test show obvious differences. Figure 5 The fitting degree of the midline trend line can reach 99.78%, indicating that the contact resistance obtained by the test is highly accurate.

[0048] In Example 1, the difference between the two slurries is mainly reflected in the difference in the glass system and content in the slurry. Through internal testing, it is preliminarily determined that the filling difference between the slurries is obvious. Therefore, this method is used to test the contact resistance of the two slurries and then screen the excellence of the glass.

[0049] Example 2:

[0050] The screen printing method of Example 2 is the same as that of Example 1, except that the line width and the spacing between different lines are changed. In Example 2, the line width is set to 500 μm, and the spacing between two adjacent lines in each row of 6 lines is distributed from dense to sparse, respectively, at 0.2, 0.4, 0.8, 1.6, and 3.2 mm.

[0051] For the screen of Example 2, the contact resistance test was carried out using the first silver paste printed electrode in Example 1. The test method was repeated in Example 1. The test results are shown in Tables 4 and Figure 6 shown.

[0052]

[0053] Comparative Example 1:

[0054] The screen printing method of Comparative Example 1 was repeated in Example 1, with the only difference being the line width and the spacing between different lines. In Comparative Example 1, the line width was set to 300 μm, and the spacing between two adjacent lines in each row of 6 lines was distributed from dense to sparse, respectively, at 0.5, 1, 2, 4, and 8 mm.

[0055] For the screen of comparative example 1, the contact resistance test was carried out by printing the electrode with the first silver paste in example 1. The test method was repeated in example 1. The test results are shown in Table 5 and Figure 7 shown.

[0056]

[0057] From the comparative example 1, it can be seen that the contact resistance value obtained by the designed screen test is less stable. Figure 7 The fitting degree of the midline trend line is only 99.19%, which is significantly lower than the test results in Example 1-2. This shows that the setting of the grid line interval is crucial in screen design.

[0058] In the examples of this invention, the length and width of the silver electrode grid lines designed in the screen have been extensively tested experimentally, ensuring that the silver-silicon contact resistance values ​​obtained after screen printing are highly stable and accurate, effectively reducing testing costs. Furthermore, the screen design ensures that different slurries can be printed and tested simultaneously, reducing the difference in contact resistance values ​​between different sources and enabling more accurate contact resistance measurements.

[0059] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be considered as being limited to the specific forms described in the embodiments.

Claims

1. A resistance test method for a silver-silicon contact resistance test screen for silicon-based photovoltaic paste, characterized in that The test screen includes a silicon wafer, a cross mark is marked in the middle of the front side of the silicon wafer to divide it into four printing areas of equal area, the four printing areas are divided into two groups with two diagonally arranged diagonally two rows of vertical grid lines, and the second group of two printing areas are arranged diagonally two rows of horizontal grid lines, each row of vertical grid lines and horizontal grid lines includes 6 grid lines of the same size, and the grid lines are parallel to each other; The length of each grid line is 15-25 mm, and the width of each grid line in each row of vertical grid lines is the same, which is 0.3-0.5 mm. From left to right, the intervals between two adjacent lines in each row of vertical lines are arranged from dense to sparse; and from top to bottom, the intervals between two adjacent lines in each row of horizontal lines are arranged from dense to sparse. The intervals between two adjacent grid lines in each row of 6 grid lines are 0.2mm, 0.4mm, 0.8mm, 1.6mm, and 3.2mm respectively; The testing method includes the following steps: marking a cross line in the middle of the front side of the silicon wafer to divide it into four printing areas of equal area, placing the silicon wafer forward into a printing machine to print silver electrodes, first placing the first silver paste and printing two rows of vertical grid lines diagonally in the first two printing areas of the silicon wafer, rotating the silicon wafer 90 degrees after drying, then placing the second silver paste and printing two rows of horizontal grid lines diagonally in the second two printing areas of the silicon wafer, placing the silicon wafers into a chain drying furnace for sintering after drying, taking out the silicon wafers after sintering to perform a contact resistance test, wherein the contact resistance test is performed by using two electric touch pens on a DC bridge device to contact two adjacent grid lines of each row of vertical grid lines or horizontal grid lines on the silicon wafer, and the resistance test result is displayed on the display screen of the DC bridge device, indicating that the test is completed.

2. The method for testing the resistance of a silver-silicon contact resistance test screen for a silicon-based photovoltaic paste according to claim 1, characterized in that The length of each grid line is 20 mm.

3. The resistance testing method of a silver-silicon contact resistance testing screen for a silicon-based photovoltaic paste according to claim 1, characterized in that Each row of vertical grid lines or horizontal grid lines is arranged in the center area of ​​the corresponding printing area.

4. The method for testing the resistance of a silver-silicon contact resistance test screen for a silicon-based photovoltaic paste according to claim 1, characterized in that The area of ​​the silicon wafer is 166 mm*166 mm.

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