A quantitative evaluation method for the interconnection quality of anisotropic conductive adhesive
Through the combination of image processing and evaluation standards, the number, location and distribution of conductive particles are quantitatively evaluated, which solves the problem of difficulty in quantifying the quality of ACF interconnection and improves the production quality of semiconductor display chips.
Patent Information
- Application Number
- CN202210290834.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-03-23
- Publication Date
- 2025-04-11
- Estimated Expiration
- 2042-03-23
AI Technical Summary
How to quantitatively evaluate the mass of anisotropic conductive glue in semiconductor display chip interconnection, especially the impact of the number, location and distribution of conductive particles on circuit connectivity.
The number and location of conductive particles are obtained through an image processing algorithm, a score table and evaluation criteria are formulated, the distribution uniformity of conductive particles is calculated, and the number, location and distribution of conductive particles are comprehensively evaluated to quantify the ACF interconnection quality.
The quantitative evaluation of ACF interconnection quality is achieved, scientific judgment standards are provided, and the production quality and reliability of TFT-LCD chips are improved.
Smart Images
Figure CN114648506B_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of conductive adhesives, and in particular to a method for quantitatively evaluating the interconnection quality of anisotropic conductive adhesives. Background Art
[0002] At present, the interconnection method of anisotropic conductive film (ACF) is often used in the production of semiconductor display chips. As an important component of semiconductor display chips, TFT-LCD (Thin Film Transistor Liquid Crystal Display) is a key device used in liquid crystal displays, with the characteristics of low power consumption, low radiation, space saving and environmental protection; ACF is a resin glue composed of polymer and conductive particles. During interconnection, the ACF is aligned and bonded to the chip, and pressurized and heated to solidify the polymer in the ACF, and capture the conductive particles between the relatively protruding conductive particles and the electrode, thereby establishing an electrical connection. The number, position and distribution of conductive particles on the TFT-LCD chip using the ACF interconnection method will affect the connectivity of the circuit. The more moderate the number of conductive particles, the better the circuit connectivity; the smaller the position offset of the conductive particles, the better the circuit connectivity; the more uniform the distribution of the conductive particles, the better the circuit connectivity. Therefore, indirectly judging the quality of ACF interconnection by evaluating the number, position and distribution of conductive particles has become a key link in the quality inspection of TFT-LCD. After obtaining the number and position of the conductive particles, how to quantitatively evaluate the quality of ACF interconnection is a technical problem that needs to be solved urgently. Summary of the invention
[0003] The present application provides a quantitative evaluation method for the interconnection quality of anisotropic conductive adhesives, the technical purpose of which is to improve the evaluation method for the interconnection quality of anisotropic conductive adhesives, and effectively quantitatively evaluate the quality of interconnection from three aspects: the number, position and distribution of conductive particles.
[0004] The above technical objectives of this application are achieved through the following technical solutions:
[0005] The present application provides a quantitative evaluation method for the interconnection quality of anisotropic conductive adhesives, which comprehensively and quantitatively evaluates the quality of interconnection from three aspects: the number of conductive particles, the position of conductive particles, and the distribution of conductive particles. Specifically, it includes:
[0006] The number and position of the conductive particles are obtained according to the image processing algorithm;
[0007] The interconnection quality of anisotropic conductive adhesive is quantitatively evaluated based on the number of conductive particles, the location of conductive particles and the distribution of conductive particles.
[0008] The quantitative evaluation of the number of conductive particles includes: formulating a conductive particle number scoring table, a high-intensity conductive particle ratio scoring table, and a conductive particle number evaluation quantitative standard table; calculating the score of the number of conductive particles on each conductive film through the conductive particle number scoring table and the high-intensity conductive particle ratio scoring table; comparing the score with the conductive particle number evaluation quantitative standard table, and obtaining a quantitative evaluation of the quality of anisotropic conductive adhesive interconnection in terms of the number of conductive particles.
[0009] Conductive particle quantity score table: Since the circuit connectivity is best when the number of conductive particles is moderate, when the number of conductive particles is too much or too little, the circuit connectivity will be affected. Therefore, the highest score is obtained when the number is moderate in the score table.
[0010] High-strength conductive particles ratio score table: Since conductive particles can be divided into high-strength conductive particles and low-strength conductive particles according to their degree of pressure, and strong conductive particles contribute more significantly to the connectivity of the circuit, the higher the ratio of high-strength conductive particles on the conductive film, the higher the score.
[0011] Quantitative standard table for conducting particle quantity evaluation: According to the scores in Table 1 and Table 2, each conductive film is divided into four levels: poor, average, good, and very good, so as to achieve the purpose of quantitative evaluation.
[0012] The quantitative evaluation of the conductive particle position includes: calculating the minimum circumscribed rectangle center position (x, y) of the conductive particles on each conductive film, thereby obtaining the skewness and kurtosis in the x-direction and y-direction, and obtaining a quantitative evaluation of the quality of the anisotropic conductive adhesive interconnection at the conductive particle position based on the skewness and kurtosis.
[0013] Evaluate the positional quality of ACF interconnection: Since the conductive particles are affected by a series of random events such as temperature and pressing force during pressing, the distribution in the x and y directions should conform to the normal distribution. Therefore, the calculated skewness and kurtosis are compared with the skewness and kurtosis of the normal distribution to quantitatively and indirectly evaluate the positional quality of ACF interconnection. If the skewness is left-leaning, it means that the ACF has an overall deviation to the right during pressing, and vice versa. If the kurtosis is greater than 3, it means that more conductive films have deviations in this direction during pressing, and vice versa.
[0014] The quantitative evaluation of the distribution of conductive particles includes: obtaining the distribution of conductive particles on each conductive film through kernel density estimation, calculating the KL divergence between the distribution and the uniform distribution, judging the uniformity of the distribution of conductive particles on the conductive film according to the KL divergence value, and completing the quantitative evaluation of the quality of anisotropic conductive adhesive interconnection in the conductive particle distribution.
[0015] Ideally, the conductive particles are evenly distributed on the conductive film, which can be regarded as a uniform distribution. However, the actual conductive particles are not evenly distributed. Therefore, an indicator needs to be calculated to describe the gap between the actual conductive particle distribution and the ideal uniform distribution. KL divergence is often used to measure the difference between the two distributions, so it can be used to indirectly describe the uniformity of the conductive particle distribution. The closer the KL divergence value is to 0, the closer the distribution of the conductive particles is to a uniform distribution, that is, the distribution of the conductive particles is more uniform and has a stronger ability to resist interference from individual outliers; the larger the KL divergence value, the less uniform the distribution of the conductive particles.
[0016] The beneficial effect of the present application is that the present application provides a quantitative quality assessment method for the number, position and distribution of conductive particles, so that a quantitative basis is provided for comprehensive judgment of the quality of ACF interconnection. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 A flowchart of a method for quantitatively evaluating the quality of ACF interconnection provided in a specific embodiment of the present application;
[0018] Figure 2 A schematic diagram of an image showing the number and position of conductive particles detected in a specific embodiment of the present application;
[0019] Figure 3 A schematic diagram of calculating the minimum circumscribed rectangle of a conductive particle in a specific embodiment of the present application;
[0020] Figure 4 This is a schematic diagram of the distribution of conductive particles obtained by performing kernel density estimation on the conductive particles on the conductive film in a specific embodiment of the present application. DETAILED DESCRIPTION
[0021] The technical solution of the present application will be described in detail below with reference to the accompanying drawings.
[0022] Figure 1 A flowchart of a method for quantitatively evaluating the quality of ACF interconnection provided in a specific embodiment of the present application is shown in FIG. Figure 1 As shown, the method includes:
[0023] (1) The number and position of conductive particles obtained by the image processing algorithm, such as Figure 2 shown.
[0024] (2) Develop a scoring table for the number of conductive particles (as shown in Table 1), a scoring table for the proportion of high-intensity conductive particles (as shown in Table 2), and a quantitative standard table for the number and quality of conductive particles (as shown in Table 3).
[0025] (3) Evaluate the quality of ACF interconnection according to the quality criteria corresponding to the scores.
[0026] (4) Calculate the center position (x, y) of the minimum circumscribed rectangle of the conductive particles on each conductive film, such as Figure 3 shown.
[0027] (5) Calculate the skewness S and kurtosis K in the x-direction and y-direction.
[0028] (6) The quality of the ACF interconnection is evaluated based on the calculated skewness and kurtosis.
[0029] (7) The distribution of conductive particles on the conductive film is obtained by kernel density estimation, such as Figure 4 shown.
[0030] (8) Calculate the KL divergence between this distribution and the uniform distribution.
[0031] (9) The uniformity of the conductive particle distribution is evaluated based on the calculated KL divergence.
[0032] (10) Comprehensive evaluation of the number of conductive particles, conductive particle positions, and conductive particle distribution is performed to complete the quantitative evaluation of the ACF interconnect quality.
[0033] Table 1 Conductive particle quantity score table
[0034] Quantity range Score ＜15 -1 15～25 1 25～30 2 30～35 1 ≥35 -1
[0035] Table 2 High-strength conductive particles percentage score table
[0036] High-intensity particle ratio range Score ＜50％ -1 50％～75％ 1 75％～90％ 2 ≥90％ 3
[0037] Table 3 Quantitative evaluation criteria for the number and quality of conductive particles
[0038] Score Conductive particle quantity and quality ≤0 Poor 1 generally 2 better ≥3 very good
[0039] The above are exemplary embodiments of the present application, and the protection scope of the present application is defined by the claims and their equivalents.
Claims
1. A quantitative evaluation method for the interconnection quality of anisotropic conductive adhesive, characterized in that: include: The number and position of the conductive particles are obtained according to the image processing algorithm; Quantitatively evaluate the interconnection quality of anisotropic conductive adhesive from the number of conductive particles, conductive particle positions and conductive particle distribution; The quantitative evaluation of the number of conductive particles includes: formulating a conductive particle number score table, a high-intensity conductive particle ratio score table, and a conductive particle number evaluation quantitative standard table, calculating the score of the number of conductive particles on each conductive film through the conductive particle number score table and the high-intensity conductive particle ratio score table, comparing the score with the conductive particle number evaluation quantitative standard table, and obtaining a quantitative evaluation of the quality of anisotropic conductive adhesive interconnection in terms of the number of conductive particles; The quantitative evaluation of the conductive particle position includes: calculating the minimum circumscribed rectangle center position (x, y) of the conductive particles on each conductive film, thereby obtaining the skewness and kurtosis in the x-direction and y-direction, and obtaining a quantitative evaluation of the quality of the anisotropic conductive adhesive interconnection at the conductive particle position based on the skewness and kurtosis; The quantitative evaluation of the distribution of conductive particles includes: obtaining the distribution of conductive particles on each conductive film through kernel density estimation, calculating the KL divergence between the distribution and the uniform distribution, judging the uniformity of the distribution of conductive particles on the conductive film according to the KL divergence value, and completing the quantitative evaluation of the quality of anisotropic conductive adhesive interconnection in the distribution of conductive particles; Among them, in the conductive particle quantity score table, the number of conductive particles in the range of 25-30 scores the highest; in the high-intensity conductive particle proportion score table, the higher the proportion of high-intensity conductive particles, the higher the score.