Method for improving quality of inkjet printing nanosilver line

Abstract

The application discloses a method for improving the quality of inkjet printing nano-silver circuit, which comprises the following steps: firstly, selecting the substrate type and measuring the thickness; then, performing plasma modification pretreatment on the surfaces of multiple groups of substrates and recording the pretreatment parameters of each group of samples; then, selecting the printing nozzle model and setting the printing parameters, including constant temperature and humidity, disturbance frequency, printing height and ink drop spacing; then, selecting multiple groups of substrate samples with different treatment parameters, setting different printing parameters for the multiple substrate samples of each group, setting the circuit printing starting point on the surface of the substrate to be printed, and starting inkjet printing of the circuit; after the printing is completed, high-temperature sintering is performed to obtain the nano-silver circuit; and the nano-silver circuit is characterized. According to the characterization results, the optimal pretreatment parameters and printing parameters are selected for inkjet printing of the nano-silver circuit. The application only needs to explore the process parameter combination once, does not need to repeat experiments for multiple times, is very suitable for the batch manufacturing situation, and simplifies the process steps and shortens the production cycle.

Description

Technical Field

[0001] This invention belongs to the field of circuit manufacturing and relates to an improved method based on inkjet printing technology, specifically a method for improving the quality of inkjet-printed nano-silver circuits. Background Technology

[0002] Circuit manufacturing is a crucial component of high-tech industries and a fundamental core element of electronic components and large electrical equipment. Circuit quality significantly impacts the performance of electronic components. With the increasing demand for miniaturization and personalization in electronic products, the ability to manufacture circuits with low resistivity and stable morphology in a simple and efficient manner is of paramount importance for electronic device manufacturing.

[0003] The etching and other processes commonly used in modern electronic circuit manufacturing are highly complex, typically requiring an image transfer process to attach metal to a substrate—a subtractive manufacturing technique. However, the correlation between the process results and parameters is not direct, leading to significant material waste, increased manufacturing costs, and potential environmental pollution. In contrast, inkjet printing, a novel additive manufacturing technique involving the deposition of nanomaterials, simply deposits patterned functional inks onto a substrate and then sintersties them to obtain the desired electronic circuits. Its advantages—independence on substrate material properties, large-area mass production capability, and low cost—offer significant process advantages over traditional electronic manufacturing, making it a promising field for electronic circuit manufacturing.

[0004] Based on this, the present invention proposes a method to improve the quality of inkjet-printed silver nanowires. The method of the present invention optimizes the forming process of inkjet-printed silver nanowires. This process does not require restrictions on the type of substrate material and can meet the needs of flexible / non-flexible electronic device circuit manufacturing at the same time. It aims to broaden the application of inkjet printing technology in the field of circuit manufacturing and improve the efficiency and save costs for the complete manufacturing of flexible / non-flexible electronic devices. Summary of the Invention

[0005] To address the problems of cumbersome processes and low material utilization in existing electronic circuit manufacturing, this invention proposes a method to improve the quality of inkjet-printed silver nanowires. This method optimizes the inkjet-printed silver nanowire forming process, enabling the fabrication of silver nanowires with the required linewidth on the substrate surface without considering substrate material characteristics. The low resistivity of these nanowires results in superior electrical properties and lower parasitic power losses in the circuit system. Furthermore, the circuit fabrication process proposed in this invention requires only one step of process parameter exploration for specific materials, making it suitable for mass production. The quality of the printed circuits can be monitored in real time during manufacturing, allowing for parameter adjustments based on practical experience and improving manufacturing efficiency.

[0006] To solve the above-mentioned technical problems and achieve the intended purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for improving the quality of inkjet-printed nano-silver circuits includes the following steps:

[0008] S1. Select a substrate based on the product type of inkjet-printed nano-silver circuitry, and determine the substrate thickness. a Perform measurements;

[0009] S2. Perform plasma modification treatment on the substrate surface, prepare multiple sets of substrate samples according to different treatment parameters, and record the pretreatment parameters of each set of samples.

[0010] S3. Printing parameter settings, details are as follows:

[0011] A plasma-modified substrate is fixed on the inkjet printing system base and a constant temperature and humidity are set.

[0012] Select the piezoelectric waveform driver, set the perturbation frequency, and observe the ink output status of the print nozzle array under a microscope to determine whether the piezoelectric driver and perturbation frequency are appropriate.

[0013] Start the inkjet printing system to conduct a nozzle ink output test, observe the ink output status of the print nozzle array in real time, and select the print nozzle model;

[0014] Observe the real-time ejection status of the nozzle, read the ink cartridge height b, and set the printing height according to the ink cartridge height b and the substrate thickness a;

[0015] A preliminary inkjet printing experiment was conducted on the substrate, and the droplet spacing of the printing process was set based on the experimental results.

[0016] S4. Select multiple substrate samples with different processing parameters, set different printing parameters for each substrate sample, set the line printing start point on the surface of the substrate to be printed, and start inkjet printing of the line.

[0017] S5. The printed circuit is sintered at high temperature to evaporate the organic solvent in the nano-silver ink and connect the metallic silver particles into lines to obtain nano-silver circuits.

[0018] S6. Perform structural and morphological characterization and resistivity testing on the nano-silver circuit. Based on the characterization results and the resistivity obtained from the test, select the optimal preprocessing parameters and printing parameters, and use the obtained preprocessing parameters and printing parameters to inkjet print the nano-silver circuit.

[0019] The method proposed in this invention can quickly determine the optimal parameters for forming nano-silver low-resistance circuits based on inkjet printing. Using these optimal parameters for inkjet printing, circuits with excellent electrical properties and low parasitic power loss can be successfully manufactured. This process has no explicit limiting relationship with the properties of the actual selected substrate material. For any substrate, by exploring specific parameter combinations according to the process provided by this invention, nano-silver circuits can be deposited at any position on its surface.

[0020] Compared with existing technologies, the more beneficial effects achieved by this invention are:

[0021] (1) This invention develops a method to improve the quality of inkjet printed nano silver circuits. The method of this invention optimizes the forming process of inkjet printed nano silver circuits, which is more efficient and cost-saving than the original circuit manufacturing technology, while ensuring the quality of the circuits.

[0022] (2) For a specific substrate, the process only needs to explore the combination of process parameters once, without repeated experiments, which is very suitable for mass production, simplifies the process steps and shortens the production cycle. Attached Figure Description

[0023] Figure 1 This is a flowchart of a method for improving the quality of inkjet-printed nano-silver circuits proposed in this invention.

[0024] Figure 2 These are circuit defect diagrams that appear during printing in this embodiment of the invention. (a) indicates a short circuit, (b) indicates an open circuit, (c) indicates an abnormal line shape, and (d) indicates normal line shape.

[0025] Figure 3 These are three-dimensional contour representations of the printed circuits in this embodiment of the invention. (e) to (n) correspond to the three-dimensional contour diagrams of the inkjet-printed circuits after the PI substrate has undergone plasma treatment for 0s, 15s, 30s, 45s, 50s, 52s, 55s, 60s, 75s, and 90s.

[0026] Figure 4 This is a schematic diagram illustrating the printing height setting in an embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram of the printing spacing setting in an embodiment of the present invention.

[0028] 100 - Nozzle, 200 - Substrate, 300 - Ink droplet, 310 - First printing line, 320 - Second printing line. Detailed Implementation

[0029] The circuit fabrication process provided by the present invention will be described in detail below with reference to the accompanying drawings.

[0030] like Figure 1 As shown, the present invention provides a method for improving the quality of inkjet-printed nano-silver circuits, comprising the following steps:

[0031] Step S1: Substrate selection and measurement. Confirm the substrate type for silver nanowire deposition and measure the substrate thickness three times using calipers. Take the average thickness. a This process is applicable to both flexible and non-flexible substrates, but because inkjet printing is a two-dimensional planar processing method, the substrate needs to be as flat as possible. The average thickness can be measured multiple times using a micrometer or vernier calipers.

[0032] For example, the thickness of the deposited substrate was measured three times with calipers and the average was 25 μm. The material was polyimide (PI), which has good biocompatibility, but it is not limited to this. In this embodiment, inkjet printing of silver nanowires will be performed using PI as the substrate.

[0033] Step S2: Substrate pretreatment. The substrate surface is subjected to plasma modification treatment. Multiple sets of substrate samples are prepared according to different treatment parameters, and the pretreatment parameters of each set of samples are recorded as follows:

[0034] (1) Clean the substrate surface of dust and other contaminants. To avoid dust, water stains, and other debris affecting the deposition of electronic circuits, use a non-woven cloth to wipe the contaminants along one direction of the substrate edges. At the same time, check the substrate for defects such as cracks, bubbles, and breaks. If defects are found, the substrate needs to be replaced. These problems will affect the quality of inkjet printing, thereby affecting the performance of the circuit.

[0035] (2) Plasma modification treatment is applied to the substrate surface. This treatment introduces hydrophilic groups onto the substrate surface, improving the adhesion between the substrate and the ink. The treatment time varies depending on the substrate type. Assuming the treatment gas and the substrate material and surface area are the same, the power... P and time t These factors collectively influence the quality of the treatment. Let's assume the treatment effect is a dimensionless number. A ,0< A <2. A The larger the size, the better the processing effect. A = k 4 P s + k 5 t s , k 4. k 5 represents the correction factor. P s For optimal power, t s The optimal time; if there are x groups of power P 1.P 2… P x ( P 1≥ P 2≥…≥ P x This caused a modified response in the substrate (printing was significantly better than the untreated substrate), with the median value being... P r ,but P s =( P r - P x ) / ( P 1- P x This refers to normalization. k 4. Take the value between 0.8 and 1.2, the median. P r near P Take 0.8, close to P x Take 1.2. t s Similarly.

[0036] When conducting experiments, it is necessary to determine an appropriate plasma treatment time. If the treatment time is too short, the substrate surface will have poor hydrophilicity and hydrophobicity, resulting in unsatisfactory ink droplet aggregation and multiple undulating patterns at the edge of the circuit. Figure 2 As shown in (c); if the processing time is too long, the line will not only have poor flatness, but also internal short circuits and open circuits may occur, such as... Figure 2 As shown in (a) and (b), even satellite ink droplets appear. When performing plasma treatment, the treatment time can be adjusted by printing line arrays with different plasma treatment times on the desired substrate. The line morphology at different treatment times can be observed under a microscope. Groups with large fluctuations or breaks in line morphology are discarded, and the group with the best flatness is selected to obtain its optimal plasma treatment time.

[0037] For example, in step S2, the plasma surface treatment time is 55 seconds. Figure 3 As shown, (e)-(n) are the three-dimensional contour observation results of the PI substrate corresponding to this preferred embodiment after plasma processing for 0s, 15s, 30s, 45s, 50s, 52s, 55s, 60s, 75s, and 90s. The group with plasma processing for 55s is selected, at which time the line contour flatness is optimal.

[0038] S3. Printing parameter settings, details are as follows:

[0039] (1) Temperature and humidity settings: Fix the substrate on the inkjet printing system base and set a constant temperature and humidity. Substrate movement will cause the line deposition position to shift, or even cause the ink droplets to fail to connect into lines. Therefore, the substrate must be completely fixed. For flexible substrates, traceless tape can be used for fixation; for non-flexible substrates, fixing clamps can be used for fixation.

[0040] In a preferred embodiment, in step S3, the ambient temperature and humidity can typically be set to room temperature of 20°C and relative humidity of 50%, and the PI substrate is completely fixed to the inkjet printing system base using traceless tape.

[0041] (2) Disturbance frequency setting: Select the piezoelectric waveform driver and set the disturbance frequency. The piezoelectric waveform driver is associated with the ink output state, and the disturbance frequency is associated with the spatial position of the inkjet printing jet break. The ink output state of the nozzle array can be observed under a microscope to achieve real-time control of the driver and the disturbance frequency. Generally, the ink output speed should be uniform and the jet break phenomenon should appear in the microscopic field of view.

[0042] As a preferred embodiment, the piezoelectric waveform driver selects a sinusoidal periodic drive, the perturbation frequency is set to 80kHz, the observed ink output speed is 3 drops per second, and complete ink droplets should appear in the field of view.

[0043] (3) Nozzle selection. When selecting the nozzle model, you can use the built-in microscope of the inkjet printer to observe the ink output status of each nozzle array. Select a single nozzle in the nozzle array with stable ink output (uniform ink output) and vertical jet shape without deviation (90° to the horizontal plane). After selecting the nozzle, you can preview the print and determine whether the nozzle selection is appropriate based on the printing situation of the specific nozzle, and avoid problems such as scattered ink dots and printhead clogging.

[0044] (4) Print height settings. For example... Figure 4 As shown, observe the ink stream ejected from the selected nozzle and read the vertical distance between nozzle 100 and the point where a single complete ink droplet is generated. b Set the final print height h = k 1 a + k 2 b , a The thickness of the substrate is 200. b This refers to the height of the ink cartridge (the height of a complete ink droplet). k 1. k Both 2 represent high-level correction factors. The selection rules for correction factors are as follows:

[0045] 1) a The average of multiple measurements of the substrate (if the 5 measurements are respectively) l 1, l 2, l 3,l 4, l 5, and l 1≥ l 2≥ l 3≥ l 4≥ l 5), a = ( l 1+ l 2+ l 3+ l 4+ l 5) / 5, and must be greater than 5. l 5. k The correction factor is 1.0-1.2. When the substrate height fluctuation is small, take 1.0 and when the height fluctuation is large, take 1.2.

[0046] 2) b The selected nozzle cartridge height is the spatial distance between the jet ejection point and the individual droplet formation point, typically taken as 750µm. When the nozzle cartridge height exceeds 750µm... k 2. Take 0.8; when the nozzle cartridge height is below 750µm, k 2 is 1.2.

[0047] 3) The nozzle movement process (printing process) has no substantial impact on the ink droplet printing height.

[0048] During inkjet printing, it is crucial to select the correct and appropriate print height. If the print height is set too low, ink droplets may not form properly, resulting in significant fluctuations or even breaks in the printed circuit. Furthermore, a print height that is too low will cause the print head to be too close to the substrate surface, compromising safety. Conversely, a print height that is set too high may cause ink droplets to form prematurely before contacting the substrate. This excessively high droplet velocity upon contact can lead to sputtering, resulting in fluctuating circuit patterns and even satellite droplet phenomena. When setting the print height, a 3D optical surface profilometer can be used to observe the quality and morphology of the printed circuit. Adjusting the print height based on practical experience will ensure high-quality printing.

[0049] In a preferred embodiment, the deposition substrate is 25μm polyimide (PI). Observing the selected nozzle, the optimal cartridge height is read as 750μm when there are no satellite ink droplets and the circuit flatness is good. The final printing height is set to 775μm.

[0050] (5) Setting the droplet spacing. First, set the maximum droplet spacing to conduct a pre-printing experiment to generate an independent droplet sequence, i.e., as shown below. Figure 5 The first line of printed lines 310 shown is observed using an optical microscope, and the radius of each individual ink droplet 300 is measured. The nozzle voltage is adjusted multiple times, and the printing and observation are repeated to obtain the average radius r. Because when the spacing between ink droplets 300 is set to the radius of a single ink droplet, such as... Figure 5The second line of print, 320, shows overlapping droplets with the most evenly aligned droplet edges. Therefore, the droplet spacing is set to the average value r. A larger droplet spacing is typically 100μm. The droplet spacing depends on the specific nozzle model selected. After selecting the droplet spacing, a test print can be performed. However, when the nozzle movement speed is too fast, the droplet spacing will change. In this case, the droplets undergo a falling motion in the vertical direction and a uniform linear motion in the horizontal direction. The droplet spacing can be calculated using a formula. ds=k 3 *v*R / Q . v This represents the nozzle movement speed (m / s) during the printing process. R The volume of a single ink droplet (m 3 ), Q Volumetric flow rate (m³) 3 / s), k 3 is the correction factor. k 3 is generally taken as 0.8-2.0.

[0051] The droplet spacing also has a significant impact on the printing quality of lines. If the droplet spacing is too large, the droplets will not connect, resulting in open circuits or defects such as holes and cracks in the lines. If the droplet spacing is too small, the lines will have multiple unevenness and poor flatness. Observe the line shape and adjust the droplet spacing setting based on practical experience.

[0052] In a preferred embodiment, the deposition substrate material is polyimide (PI). An inkjet printing pre-printing experiment is conducted through a selected nozzle. The initial droplet spacing is set to 100 μm. The printing circuit is observed in an optical microscope and the radius of a single droplet in an independent droplet sequence is measured. Subsequently, the nozzle voltage is adjusted multiple times, and the printing and observation are repeated. Finally, the average radius of a single droplet is determined to be 15 μm. Therefore, the inkjet printing droplet spacing is set to 15 μm.

[0053] Step S4: Formal printing. Select multiple substrate samples with different processing parameters. Set different printing parameters for each substrate sample, set the circuit printing start point, import the circuit model.bmp file and set the circuit printing start point, then start printing. The printing start point can be recorded in real time using the inkjet printing system's built-in positioning function.

[0054] Example: The substrate samples are grouped as follows:

[0055] Multiple substrate samples with the same pretreatment parameters are grouped together. Different printing parameters are selected for each substrate sample in the group for observation and screening. Different pretreatment parameters are selected for different groups of substrate samples. This allows for multi-parameter combinations to select the optimal parameters.

[0056] In a preferred embodiment, the deposition substrate is 25μm polyimide (PI), which undergoes plasma treatment for 55s, followed by inkjet printing through a selected nozzle. The printing height is 775μm, and the droplet spacing is 15μm, resulting in high-quality circuitry. Figure 2 As shown in (d).

[0057] Step S5: High-temperature sintering of the circuit. Place the printed substrate into a vacuum drying oven for high-temperature sintering of the circuit. Ensure the printed substrate is firmly fixed. After sintering, a circuit sample with nano-silver circuitry will be obtained.

[0058] In a preferred embodiment, the sintering temperature is 150 °C and the sintering time is 45 min.

[0059] S6. Characterize the structure and morphology of the nano-silver circuit and test its resistivity. Based on the characterization results and the measured resistivity, select the optimal preprocessing and printing parameters, and use these parameters for inkjet printing of the nano-silver circuit. The specific tests are as follows:

[0060] (1) Three-dimensional profile test. Using a 3D profiler, three longitudinal sections of the prepared line are arbitrarily selected for three-dimensional profile observation. The nonlinear error of the profile is calculated, and the line groups with unstable profiles are eliminated. The groups with excellent profiles are selected and the average cross-sectional area of ​​the three longitudinal sections is calculated. S .

[0061] (2) SEM test. The distribution of nano-silver particles inside the circuit was observed using an SEM electron microscope. Circuit groups with more pores were discarded, and the circuit group with the lowest porosity was selected.

[0062] (3) Resistivity test. A probe instrument is used to test the resistivity at a fixed length. L line resistance R The obtained average cross-sectional area S Substitute into the resistivity formula ρ = RS / L Calculating resistivity helps evaluate electrical performance. The lower the resistivity, the better the circuit performance, the smaller its parasitic resistance, and the less unnecessary electrical loss.

[0063] It should be noted that the substrate type of this invention is not limited. Although polyimide was used as a flexible substrate in the above example, it can actually be a flexible substrate or a rigid substrate.

[0064] Advantages of this invention:

[0065] This invention provides a method for improving the quality of inkjet-printed silver nanowires. It is a complete process flow for depositing low-resistivity electronic circuits on a substrate, broadening the application of inkjet printing technology in the field of circuit manufacturing. By exploring the optimal combination of process parameters for inkjet printing on the desired substrate according to the process steps provided by this invention, silver nanowires with low resistivity and smooth morphology can be printed on the substrate.

[0066] The process provided by this invention utilizes inkjet printing technology, which is simpler and more convenient than conventional etching or mask manufacturing. While ensuring the quality of circuit manufacturing, it can achieve array-style mass production to a certain extent, greatly saving material and machine costs.

[0067] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several technical improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for improving the quality of inkjet-printed nano-silver circuits, characterized in that, Includes the following steps: S1. Select a substrate based on the product type of inkjet-printed nano-silver circuitry, and determine the substrate thickness. a Perform measurements; S2. Perform plasma modification treatment on the substrate surface, prepare multiple sets of substrate samples according to different treatment parameters, and record the pretreatment parameters of each set of samples. S3. Printing parameter settings, as follows: A plasma-modified substrate is fixed on the inkjet printing system base and a constant temperature and humidity are set. Select the piezoelectric waveform driver, set the perturbation frequency, and observe the ink output status of the print nozzle array under a microscope to determine whether the piezoelectric driver and perturbation frequency are appropriate. Start the inkjet printing system to conduct a nozzle ink output test, observe the ink output status of the print nozzle array in real time, and select the print nozzle model; Observe the real-time ejection status of the nozzle, read the ink cartridge height b, and set the printing height according to the ink cartridge height b and the substrate thickness a; A preliminary inkjet printing experiment was conducted on the substrate, and the droplet spacing of the printing process was set based on the experimental results. S4. Select multiple substrate samples with different processing parameters, set different printing parameters for each substrate sample, set the line printing start point on the surface of the substrate to be printed, and start inkjet printing of the line. S5. The printed circuit is sintered at high temperature to evaporate the organic solvent in the nano-silver ink and connect the metallic silver particles into lines to obtain nano-silver circuits. S6. Characterize the structure and morphology of the nano-silver circuit and test its resistivity. Select the optimal preprocessing parameters and printing parameters based on the characterization results and the measured resistivity. Use the obtained preprocessing parameters and printing parameters to inkjet print the nano-silver circuit. In step S2, the plasma modification treatment is a plasma modification treatment, and the pretreatment parameters include the pretreatment time. t and power P The preprocessing effect is set to dimensionless. A ,0< A <2; A The larger the value, the better the processing effect; therefore, the preprocessing effect... A = k 4 P s + k 5 t s , k 4. k 5 represents the correction factor. P s For optimal power, t s The optimal time; Define x groups of power P 1. P 2… P x ,in P 1≥ P 2≥…≥ P x This causes the substrate to produce a modified response, with the median value being... P r ,but P s =( P r - P x ) / ( P 1- P x ); if the median value P r Closer P 1, k 4 is taken as 0.8, if the median value is closer P x , k 4 is taken as 1.2; k 5 can be 0.7 or 1.

3. t s Calculation method and P s same; In step S3, a correction factor is introduced into the calculation when setting the print height. h = k 1 a + k 2 b , k 1. k Both 2 are height correction factors, and the selection rules for the correction factors are as follows: k The correction factor is set to either 1.0 or 1.

2. a This is the average of multiple measurements of the substrate thickness; b The threshold is set to the nozzle cartridge height and the spatial distance between the jet ejection point and the point where a single ink droplet is generated. b 0, when the nozzle cartridge height is higher than the threshold. b At 0 o'clock, k 2. Take 0.8; when the nozzle cartridge height is lower than b At 0 o'clock, k 2 is taken as 1.2; In step S3, the ink droplet spacing is determined as follows: First, a preliminary inkjet printing experiment was conducted with the maximum droplet spacing set to generate an independent droplet sequence. The printed path was observed using an optical microscope, and the radius of each individual droplet was measured. The nozzle voltage was adjusted multiple times, and the printing and observation were repeated to obtain the average radius r. The droplet spacing was then set. ds=r .

2. The method for improving the quality of inkjet-printed silver nanowires according to claim 1, characterized in that, In step S1, the substrate thickness is measured at least three times in different regions using vernier calipers, and the average thickness of the multiple measurements is taken as the substrate thickness. a .

3. The method for improving the quality of inkjet-printed silver nanowires according to claim 1, characterized in that, In step S3, the temperature range is 18℃~30℃ and the relative humidity is 40%~60% under constant temperature and humidity conditions.

4. The method for improving the quality of inkjet-printed silver nanowires according to claim 1, characterized in that, In step S3, the method for determining whether the constant voltage electric drive and the disturbance frequency are appropriately selected is as follows: The ink output state of the nozzle array is observed under a microscope. A uniform ink output speed and the appearance of jet breakage in the microscopic field of view indicate a suitable condition.

5. The method for improving the quality of inkjet-printed nano-silver circuits according to claim 1, characterized in that, In step S6, a 3D profilometer is used to arbitrarily cut the longitudinal section of the prepared nano-silver circuit for three-dimensional profile observation, calculate the nonlinear error of the profile, eliminate the circuit group with unstable profile, and select the group with excellent profile; calculate the average cross-sectional area of ​​the longitudinal section. The distribution of silver nanoparticles inside the silver nanowires was observed using SEM electron microscopy. The circuit groups with more pores were discarded, and the circuit groups with the lowest porosity were selected. Testing a fixed length using a prober L line resistance R The obtained average cross-sectional area S Substitute into the resistivity formula ρ = RS / L Calculate resistivity to aid in the evaluation of electrical performance.

Images