CN117542945B - A method for bonding a flip-chip MICRO LED chip to a substrate - Google Patents

Abstract

The present invention discloses a method for bonding a flip-chip MICRO LED chip to a substrate, comprising: establishing a three-dimensional solid model and a finite element model of a bonding head, and performing model analysis to determine characteristic parameters of the bonding head; based on the characteristic parameters of the bonding head, determining the weak parts of the bonding head and optimizing the structural mechanical properties of the weak parts; fixing the flip-chip MICRO LED chip on the substrate based on the optimized bonding head, and then performing gold wire bonding on the flip-chip MICRO LED chip placed on the substrate. Performing preliminary bonding based on the optimized bonding head is convenient for reducing large deformation and/or residual vibration generated under the action of impact loads and periodic excitation forces, and is convenient for improving the bonding accuracy of the chip. Performing gold wire bonding on the flip-chip MICRO LED chip placed on the substrate further improves the bonding accuracy and achieves reliable connection.

Description

A bonding method for flip-chip MICRO LED chip and substrate

Technical Field

The present invention relates to the technical field of chip bonding, and in particular to a method for bonding a flip-chip MICRO LED chip to a substrate.

Background technique

At present, MicroLED display technology has attracted widespread attention due to its advantages such as fast response speed, low power consumption, long life and high luminous efficiency, and is considered to be the next generation display technology after LCD. MicroLED display technology requires bonding the MicroLED chip to the substrate for electrical connection to achieve drive control.

In the prior art, a MICRO LED chip is bonded to a substrate through a bonding head. For example, a Chinese invention patent application with publication number CN107134427A, publication date September 5, 2017, and invention name “Chip bonding device and method” provides a chip bonding device, including a carrier, a bonding head structure and a bonding platform. The existing flip chip bonding process includes the following steps: providing a plurality of chips and a substrate to be bonded, wherein the chip includes a device surface; then, placing the plurality of chips on the carrier with the device surface facing upward, and then, using a grabbing and flipping structure to grab and flip the chips; thereafter, handing the chips to the bonding head structure through a handover structure, and the bonding head structure adsorbs a plurality of chips through its chip carrying component. When the plurality of chips are moved by the bonding head structure to above the substrate on the bonding platform, the alignment marks of the chips and the alignment marks of the substrate are aligned through a CCD image sensor, and finally, the chips on the bonding head structure are bonded to the substrate at one time.

The technical problems existing in the above prior art are: when flip-chip MICRO LED chip packaging, the bonding head often produces large deformation and/or residual vibration under the action of impact load and periodic excitation force due to insufficient structural rigidity, which directly affects the bonding accuracy of the chip.

Summary of the invention

The present invention aims to solve at least one of the technical problems in the above-mentioned technology to a certain extent. To this end, the purpose of the present invention is to provide a bonding method for a flip-chip MICRO LED chip and a substrate to improve the bonding accuracy of the MICRO LED chip.

To achieve the above object, an embodiment of the present invention provides a method for bonding a flip-chip MICRO LED chip to a substrate, comprising:

Establish a three-dimensional solid model and finite element model of the bond head, and perform model analysis to determine the characteristic parameters of the bond head;

Based on the characteristic parameters of the bonding head, the weak parts of the bonding head are determined and the structural mechanical properties of the weak parts are optimized;

The flip-chip MICRO LED chip is fixed on the substrate based on the optimized bonding head, and then the flip-chip MICRO LED chip placed on the substrate is bonded with gold wires.

According to some embodiments of the present invention, a three-dimensional solid model and a finite element model of a bonding head are established, and model analysis is performed to determine characteristic parameters of the bonding head, including:

Obtain the flip chip bonding process characteristics and the overall physical structure of the bonding head, and establish a three-dimensional solid model of the bonding head;

Set the finite element simplification principle of the bond head and establish the finite element model of the bond head;

For the three-dimensional solid model and the finite element model, the static and dynamic structural mechanical properties of the bond head are analyzed through the model, the static deformation of the bond head under static load and the dynamic deformation under dynamic load are calculated, and the first constraint modal characteristics of the bond head with the pick-up head assembly installed under braking and non-braking conditions and the second constraint modal characteristics of the bond head without the pick-up head assembly installed under braking and non-braking conditions are analyzed;

The characteristic parameters of the bonding head are determined according to the static deformation, the dynamic deformation, the first constraint modal characteristics and the second constraint modal characteristics.

According to some embodiments of the present invention, optimizing the structural mechanical properties of a weak component includes:

An optimization method combining design parameter selection based on sensitivity analysis and optimal solution extraction based on hierarchical analysis method is used to optimize the structural mechanical properties of weak components.

According to some embodiments of the present invention, gold wire bonding is performed on a flip-chip MICRO LED chip placed on a substrate, comprising:

Based on the first gold wire, a gold ball is implanted at the position of the PAD of the flip-chip MICRO LED chip;

The gold wire bonding is completed based on the gold finger connecting the gold ball and the substrate with the second gold wire.

According to some embodiments of the present invention, the second gold wire is connected to the gold ball and the gold finger of the substrate by one of gold wire ball welding, ultrasonic wedge welding, hot pressure welding, and thermosonic welding.

According to some embodiments of the present invention, the bonding method of the second gold wire to the gold ball is spherical bonding.

According to some embodiments of the present invention, before the flip-chip MICRO LED chip is fixed on the substrate based on the optimized bonding head, the method further includes:

Detecting a first thickness of a flip-chip MICRO LED chip and a second thickness of a substrate;

Acquire attribute information of the flip-chip MICRO LED chip and query a preset data table to determine a first preset distance between the upper surface of the flip-chip MICRO LED chip and the lower surface of the substrate and a second preset distance between the lower surface of the flip-chip MICRO LED chip and the upper surface of the substrate;

According to the first preset distance, the first thickness and the second thickness, the actual distance between the flip-chip MICRO LED chip and the substrate is calculated;

It is determined whether the actual distance is consistent with the second preset distance. If it is determined that they are inconsistent, the bonding head for placing the flip-chip MICRO LED chip is moved to make the actual distance consistent with the second preset distance.

According to some embodiments of the present invention, detecting a first thickness of a flip-chip MICRO LED chip includes:

Generate ranging signals for flip-chip MICRO LED chips;

emitting laser according to the ranging signal;

The laser is phase modulated based on a phase modulator to generate positive and negative frequency sidebands, and the modulated laser signal is passed through an optical filter to generate a target optical signal related to the free spectral range of the optical filter;

The time difference between the emission and return of the target light signal is measured; and the first thickness of the flip-chip MICRO LED chip is determined according to the time difference and the light speed information.

According to some embodiments of the present invention, before the flip-chip MICRO LED chip is fixed on the substrate based on the optimized bonding head, the method further includes:

Acquiring a scene image of the upper surface of the substrate;

Preprocessing the scene image to obtain a preprocessed image;

The preprocessed image is processed based on the Gaussian Laplace function with 0 as the center and Gaussian standard deviation as σ, and the discrete points are determined and removed to obtain the target image;

Grayscale processing and region division are performed on the target image to determine several local regions;

Determine the absolute value of the difference between the grayscale value of each pixel and the grayscale values of each adjacent pixel in each local area, and use the largest absolute value as the flatness value of the corresponding pixel to determine whether it is within a preset flatness value range;

Calculate the ratio of the number of pixels in each local area whose flatness values are not within the preset flatness value range to the total number of pixels in the local area, and determine whether it is greater than the preset ratio;

When it is determined that the ratio is greater than the preset ratio, the corresponding local area is determined as the area to be processed, and the area to be processed is flattened.

According to some embodiments of the present invention, the preprocessing includes image noise reduction and image enhancement processing.

The present invention proposes a method for bonding a flip-chip MICRO LED chip to a substrate. Based on a three-dimensional solid model and a finite element model of a bonding head, model analysis is performed to determine characteristic parameters of the bonding head; based on the characteristic parameters of the bonding head, weak components of the bonding head are determined and the structural mechanical properties of the weak components are optimized; preliminary bonding is performed based on the optimized bonding head, so as to reduce large deformation and/or residual vibration under the action of impact loads and periodic excitation forces, and to improve the bonding accuracy of the chip; gold wire bonding is performed on the flip-chip MICRO LED chip placed on the substrate, so as to further improve the bonding accuracy and achieve reliable connection.

Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

FIG. 1 is a flow chart of a method for bonding a flip-chip MICRO LED chip to a substrate according to an embodiment of the present invention;

FIG2 is a flow chart of determining characteristic parameters of a bonding head according to an embodiment of the present invention;

FIG. 3 is a flow chart of performing gold wire bonding on a flip-chip MICRO LED chip placed on a substrate according to an embodiment of the present invention.

Detailed ways

The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

As shown in FIG. 1 , an embodiment of the present invention provides a method for bonding a flip-chip MICRO LED chip to a substrate, including steps S1-S3:

S1. Establish a three-dimensional solid model and a finite element model of the bonding head, and perform model analysis to determine characteristic parameters of the bonding head;

S2. Based on the characteristic parameters of the bonding head, determine the weak parts of the bonding head and optimize the structural mechanical properties of the weak parts;

S3. Fix the flip-chip MICRO LED chip on the substrate based on the optimized bonding head, and then perform gold wire bonding on the flip-chip MICRO LED chip placed on the substrate.

Working principle of the above technical solution: In this embodiment, the characteristic parameters include the static deformation of the bond head under static load, the dynamic deformation under dynamic load, the first constraint modal characteristics of the bond head with the pick-up head assembly installed under braking and non-braking conditions, the second constraint modal characteristics of the bond head without the pick-up head assembly installed under braking and non-braking conditions, etc.

In this embodiment, based on the characteristic parameters of the bond head, the weak parts of the bond head are determined, and the parts that most affect the bond head to produce large deformation and/or residual vibration under various working conditions are determined as weak parts. The structural mechanical properties of the weak parts are optimized to improve the overall mechanical properties of the bond head.

In this embodiment, the flip-chip MICRO LED chip is fixed on the substrate based on the optimized bonding head, and preliminary bonding is performed based on the optimized bonding head, so as to reduce the large deformation and/or residual vibration generated under the action of impact load and periodic excitation force, and to improve the bonding accuracy of the chip.

In this embodiment, gold wire bonding is performed on the flip-chip MICRO LED chip placed on the substrate, so as to further improve the bonding accuracy, ensure the bonding process, ensure the stability of the connection, so that the circuit signal on the chip can be transmitted to the substrate pin, improve the connection quality, and improve the reliability of the package.

The beneficial effects of the above technical solution are as follows: based on the three-dimensional solid model and finite element model of the bonding head, and performing model analysis, the characteristic parameters of the bonding head are determined; based on the characteristic parameters of the bonding head, the weak parts of the bonding head are determined and the structural mechanical properties of the weak parts are optimized; preliminary bonding is performed based on the optimized bonding head, which is convenient for reducing large deformation and/or residual vibration under the action of impact loads and periodic excitation forces, and is convenient for improving the bonding accuracy of the chip, and gold wire bonding is performed on the flip-chip MICRO LED chip placed on the substrate, so as to further improve the bonding accuracy and achieve reliable connection.

As shown in FIG. 2 , according to some embodiments of the present invention, a three-dimensional solid model and a finite element model of a bonding head are established, and model analysis is performed to determine characteristic parameters of the bonding head, including steps S11-S14:

S11, obtaining the flip chip bonding process characteristics and the overall physical structure of the bonding head, and establishing a three-dimensional solid model of the bonding head;

S12, setting the finite element simplification principle of the bonding head and establishing a finite element model of the bonding head;

S13. Analyze the static and dynamic structural mechanical properties of the bond head through the three-dimensional solid model and the finite element model, calculate the static deformation of the bond head under the static load, the dynamic deformation under the dynamic load, analyze the first constraint modal characteristics of the bond head with the pick-up head assembly installed under braking and non-braking conditions, and analyze the second constraint modal characteristics of the bond head without the pick-up head assembly installed under braking and non-braking conditions;

S14, determining characteristic parameters of the bonding head according to the static deformation, the dynamic deformation, the first constraint modal characteristics and the second constraint modal characteristics.

Working principle and beneficial effects of the above technical solution: Constrained modal characteristics are usually related to structural dynamics and engineering vibration analysis. In the case of unconstrained free vibration, the structure will exhibit a series of natural frequencies and corresponding modal shapes. In constrained modal analysis, the structure is restricted to vibrate under certain boundary or constraint conditions, which may affect or change its natural frequencies and modal shapes. Constrained modal analysis is mainly used in the following situations: Determine the vibration characteristics of the structure under specific constraint conditions. For example, if the structure is fixed at both ends, its vibration characteristics will be different from the unconstrained free vibration characteristics. Predict the vibration response of the structure under specific constraint conditions during the design process. In structural optimization, constrained modal characteristics can be used as objective functions or constraints. Constrained modal characteristics analysis is usually calculated using finite element method (FEM), finite difference method (FDM) or other numerical methods. These methods are able to handle complex boundary conditions and nonlinear dynamic behaviors.

In this embodiment, when establishing the three-dimensional solid model of the bond head, not only the overall solid structure of the bond head is considered, but also the characteristics of the flip chip bonding process are considered, so as to improve the accuracy of constructing the three-dimensional solid model of the bond head. The finite element simplification principle of the bond head is set, and the finite element model of the bond head is established, so as to facilitate better analysis of relevant parameters. In this embodiment, the static and dynamic structural mechanical characteristics of the bond head are analyzed through the model for the three-dimensional solid model and the finite element model, including data acquisition under various working conditions, including calculating the static deformation of the bond head under static load, the dynamic deformation under dynamic load, analyzing the first constraint modal characteristics of the bond head with the pick-up head assembly installed under braking and non-braking conditions, and the second constraint modal characteristics of the bond head without the pick-up head assembly installed under braking and non-braking conditions; comprehensively realizing comprehensive and accurate model analysis, so as to facilitate accurate determination of the static and dynamic structural mechanical characteristics of the bond head, and then determine the accurate characteristic parameters of the bond head.

According to some embodiments of the present invention, optimizing the structural mechanical properties of a weak component includes:

An optimization method combining design parameter selection based on sensitivity analysis and optimal solution extraction based on hierarchical analysis method is used to optimize the structural mechanical properties of weak components.

Working principle and beneficial effects of the above technical solution: Combining sensitivity analysis and hierarchical analysis to optimize the structural mechanical properties of weak components can effectively determine key design parameters and extract the optimal solution to improve the performance of components. The steps can be: Determine the objective function: First, it is necessary to clarify the objective of weak component optimization. This can be a certain characteristic index, such as maximum strength, minimum flexibility, minimum weight, etc. The objective function can be defined based on these indicators. Select design variables: During the design process, there are many parameters that can affect the performance of the component. Through sensitivity analysis, it can be determined which parameters have the most significant impact on the objective function. These parameters become design variables. Build a model: Use finite element analysis (FEA) or other numerical simulation methods to build a model to predict the impact of design variables on the objective function. Convert physical problems into mathematical problems. Sensitivity analysis: Use sensitivity analysis to evaluate the degree of influence of each design variable on the objective function. This is done by differentiating the model or using specialized software tools. Hierarchical analysis: Based on the results of sensitivity analysis, the design variables are divided into different levels. The most important variables are at the top level, the less important variables are at the next level, and so on. Optimization: At each level, an optimization algorithm (such as genetic algorithm, particle swarm optimization, etc.) is used to find the optimal solution. This is to take into account the variables of each layer at the same time and find the combination of variables that can make the objective function reach the optimal value. Evaluation and feedback: After finding the optimal solution at each level, the solution should be evaluated. This includes checking whether the solution meets certain constraints (such as feasibility, economy, etc.), and comparing the optimal solutions at different levels to determine the overall optimal solution. Finally, the optimal solution is fed back to the original problem and a new round of optimization is carried out. The optimization method that combines the design parameter optimization based on sensitivity analysis and the optimal solution extraction based on the hierarchical analysis method facilitates the accurate and rapid optimization of the structural mechanical properties of weak components.

As shown in FIG. 3 , according to some embodiments of the present invention, gold wire bonding is performed on a flip-chip MICRO LED chip placed on a substrate, including steps S31-S32:

S31, implanting a gold ball at the position of the PAD of the flip-chip MICRO LED chip based on the first gold wire;

S32, completing gold wire bonding by connecting the gold ball and the gold finger of the substrate based on the second gold wire.

Working principle of the above technical solution: In this embodiment, the first gold wire and the second gold wire have the same specifications, both of which are 4N gold wires. Since the resistivity of 4N gold wire is small, it is convenient to realize efficient signal transmission. One end of the second gold wire is fixed on the gold ball, and the other end is fixed on the gold finger of the substrate for connection.

The beneficial effects of the above technical solution are as follows: one end of the second gold wire is fixed on the gold ball to avoid the problem of metal compound growth, and the gold wire bonding is completed based on the gold finger connecting the gold ball and the substrate with the second gold wire, which further improves the bonding accuracy. At the same time, signal transmission is performed based on the second gold wire to achieve high efficiency and reliability of signal transmission.

According to some embodiments of the present invention, the second gold wire is connected to the gold ball and the gold finger of the substrate by one of gold wire ball welding, ultrasonic wedge welding, hot pressure welding, and thermosonic welding.

The beneficial effects of the above technical solution are: it is easy to achieve stable connection between the second gold wire and the gold ball and the gold finger of the substrate, thereby improving reliability.

According to some embodiments of the present invention, the bonding method of the second gold wire to the gold ball is spherical bonding.

The beneficial effect of the above technical solution is that it facilitates stable and accurate bonding.

According to some embodiments of the present invention, before the flip-chip MICRO LED chip is fixed on the substrate based on the optimized bonding head, the method further includes:

Detecting a first thickness of a flip-chip MICRO LED chip and a second thickness of a substrate;

Acquire the property information of the flip-chip MICRO LED chip and query the preset data table to determine a first preset distance between the upper surface of the flip-chip MICRO LED chip and the lower surface of the substrate and a second preset distance between the lower surface of the flip-chip MICRO LED chip and the upper surface of the substrate;

According to the first preset distance, the first thickness and the second thickness, the actual distance between the flip-chip MICRO LED chip and the substrate is calculated;

Determine whether the actual distance is consistent with the second preset distance. When it is determined that they are inconsistent, move the bonding head for placing the flip-chip MICRO LED chip to make the actual distance consistent with the second preset distance.

Working principle of the above technical solution: In this embodiment, the attribute information includes the shape and size of the flip-chip MICRO LED chip. The preset data table is a correspondence table of preset attribute information-first preset distance and second preset distance, which serves as a bonding process parameter table.

In this embodiment, the actual distance is a value obtained by subtracting the first thickness and the second thickness from the first preset distance.

The above technical solution has the beneficial effect of judging whether the actual distance is consistent with the second preset distance. If it is determined that they are inconsistent, the bonding head for placing the flip-chip MICRO LED chip is moved to make the actual distance consistent with the second preset distance, thereby eliminating the inconsistency between the thickness of the MICRO LED chip and the substrate and the corresponding preset thickness caused by the process of manufacturing the MICRO LED chip and the substrate, and the deviation in the bonding process. It is convenient for the deformation amount of the flip-chip MICRO LED chip and the substrate to be consistent with the preset deformation amount during bonding, so that the flip-chip MICRO LED chip and the substrate have good electrical connectivity, and the signal transmission rate is guaranteed.

According to some embodiments of the present invention, detecting a first thickness of a flip-chip MICRO LED chip includes:

Generate ranging signals for flip-chip MICRO LED chips;

emitting laser according to the ranging signal;

The laser is phase modulated based on a phase modulator to generate positive and negative frequency sidebands, and the modulated laser signal is passed through an optical filter to generate a target optical signal related to the free spectral range of the optical filter;

The time difference between the emission and return of the target light signal is measured; and the first thickness of the flip-chip MICRO LED chip is determined according to the time difference and the light speed information.

The working principle and beneficial effects of the above technical solution: In this embodiment, the laser is phase modulated based on the phase modulator to generate positive and negative frequency sidebands. After the modulated laser signal passes through the optical filter, a target light signal related to the free spectrum range of the optical filter is generated; it is convenient to implement filtering, eliminate irrelevant signals, obtain a stable and consistent target light signal, and achieve signal unification. Measure the time difference between the target light signal from emission to return; determine the first thickness of the flip-chip MICRO LED chip based on the time difference and light speed information. It is convenient to accurately calculate the first thickness of the flip-chip MICRO LED chip.

In one embodiment, the principle of detecting the second thickness of the substrate is consistent with the principle of detecting the first thickness of the flip-chip MICRO LED chip, and will not be described in detail herein.

According to some embodiments of the present invention, before the flip-chip MICRO LED chip is fixed on the substrate based on the optimized bonding head, the method further includes:

Acquiring a scene image of the upper surface of the substrate;

Preprocessing the scene image to obtain a preprocessed image;

The preprocessed image is processed based on the Gaussian Laplace function with 0 as the center and Gaussian standard deviation as σ, and the discrete points are determined and removed to obtain the target image;

Grayscale processing and region division are performed on the target image to determine several local regions;

Determine the absolute value of the difference between the grayscale value of each pixel and the grayscale values of each adjacent pixel in each local area, and use the largest absolute value as the flatness value of the corresponding pixel to determine whether it is within a preset flatness value range;

Calculate the ratio of the number of pixels in each local area whose flatness values are not within the preset flatness value range to the total number of pixels in the local area, and determine whether it is greater than the preset ratio;

When it is determined that the ratio is greater than the preset ratio, the corresponding local area is determined as the area to be processed, and the area to be processed is flattened.

The working principle of the above technical solution: In this embodiment, before the flip-chip MICRO LED chip is fixed on the substrate based on the optimized bonding head, it also includes obtaining a scene image of the upper surface of the substrate; preprocessing the scene image to obtain a preprocessed image; facilitating the acquisition of accurate images, eliminating the influence of noise, and facilitating the subsequent improvement of the accuracy of image processing.

In this embodiment, the preprocessed image is processed based on a Laplace Gaussian function with 0 as the center and a Gaussian standard deviation of σ, and discrete points are determined and removed to obtain a target image, including:

Wherein, LoG(x, y) is the Laplace function of Gaussian; x, y are the coordinates of the pixel points in the preprocessed image, σ represents the standard deviation, π is the pi, and e represents the natural constant.

Based on the Gaussian Laplace function, the areas where the intensity changes rapidly in the image can be highlighted, and then the discrete points can be accurately determined, the influence of noise pixels can be eliminated, and the target image can be obtained, which is convenient for the noise pixels to detect whether the subsequent substrate is flat.

In this embodiment, the target image is grayed and divided into regions to determine several local regions; the absolute value of the difference between the gray value of each pixel in each local region and the gray value of each of its adjacent pixels is determined, and the largest absolute value is used as the flat value of the corresponding pixel to determine whether it is within the preset flat value range; the ratio of the number of pixels in each local region whose flat values are not within the preset flat value range to the total number of pixels in the local region is calculated, and it is determined whether it is greater than the preset ratio; when it is determined that the ratio is greater than the preset ratio, the corresponding local region is determined to be the region to be processed, and the region to be processed is flattened. It is convenient to accurately determine the region to be processed, that is, the non-flat region, and flatten the region to be processed, avoiding flattening the entire region, thereby improving the speed and pertinence of the flattening process.

The beneficial effects of the above technical solution are: the area to be processed is flattened to avoid flattening the entire area, which improves the rate and specificity of the flattening process, and facilitates the subsequent improvement of the bonding accuracy when the flip-chip MICRO LED chip is fixed on the substrate based on the optimized bonding head.

According to some embodiments of the present invention, the preprocessing includes image noise reduction and image enhancement processing.

The beneficial effects of the above technical solution are: image noise reduction and image enhancement are achieved, and image accuracy is ensured.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims (9)

1. A bonding method of flip-chip MICRO LED chip and substrate, comprising:

Establishing a three-dimensional entity model and a finite element model of the bonding head, performing model analysis, and determining characteristic parameters of the bonding head;

Determining a weak part of the bonding head and optimizing the structural mechanical characteristics of the weak part based on the characteristic parameters of the bonding head;

fixing the flip MICRO LED chip on a substrate based on an optimized bonding head, and performing gold wire bonding on the flip MICRO LED chip placed on the substrate;

Establishing a three-dimensional entity model and a finite element model of the bonding head, performing model analysis, and determining characteristic parameters of the bonding head, wherein the method comprises the following steps:

Acquiring the bonding process characteristics of the flip chip and the overall entity structure of the bonding head, and establishing a three-dimensional entity model of the bonding head;

setting a bonding head finite element simplification principle, and establishing a finite element model of the bonding head;

For the three-dimensional solid model and the finite element model, the static deformation of the bonding head under the static load effect and the dynamic deformation of the bonding head under the dynamic load effect are calculated through the model analysis, the first constraint mode characteristics of the bonding head provided with the pick-up head component under the braking and non-braking working conditions are analyzed, and the second constraint mode characteristics of the bonding head not provided with the pick-up head component under the braking and non-braking working conditions are analyzed;

determining characteristic parameters of the bonding head according to the static deformation, the dynamic deformation, the first constraint mode characteristics and the second constraint mode characteristics;

optimizing structural mechanical properties of a weak part, comprising:

The design parameters based on sensitivity analysis are preferably optimized by an optimization method combining the optimal solution extraction based on analytic hierarchy process to optimize the structural mechanical characteristics of the weak component.

2. The bonding method of the flip-chip MICRO LED chip to the substrate according to claim 1, wherein the gold wire bonding of the flip-chip MICRO LED chip placed on the substrate comprises:

implanting gold balls at the PAD position of the flip-chip MICRO LED chip based on the first gold wires;

and (5) connecting the gold ball with the gold finger of the substrate based on the second gold wire to finish gold wire bonding.

3. The bonding method of flip-chip MICRO LED chip and substrate according to claim 2, wherein the second gold wire is connected to the gold ball and the gold finger of the substrate by one of ultrasonic wedge bonding, thermocompression bonding, and thermosonic bonding.

4. The bonding method of flip-chip MICRO LED chip and substrate according to claim 2, wherein the bonding method of the gold ball and the gold finger of the substrate is gold ball bonding.

5. The bonding method of flip-chip MICRO LED chip and substrate according to claim 2, wherein the bonding mode of the second gold wire to the gold ball is ball bonding.

6. The method of bonding a flip-chip MICRO LED chip to a substrate of claim 1, further comprising, prior to securing the flip-chip MICRO LED chip to the substrate based on the optimized bond head:

Detecting a first thickness of the flip-chip MICRO LED chip and a second thickness of the substrate;

Acquiring attribute information of the flip MICRO LED chip, inquiring a preset data table, and determining a first preset distance between the upper surface of the flip MICRO LED chip and the lower surface of the substrate and a second preset distance between the lower surface of the flip MICRO LED chip and the upper surface of the substrate;

according to the first preset distance, the first thickness and the second thickness, calculating to obtain the actual distance between the flip MICRO LED chip and the substrate;

And judging whether the actual distance is consistent with the second preset distance, and moving a bonding head for placing the flip MICRO LED chip to enable the actual distance to be consistent with the second preset distance when the actual distance is inconsistent with the second preset distance.

7. The method of bonding a flip-chip MICRO LED chip to a substrate of claim 6, wherein detecting the first thickness of the flip-chip MICRO LED chip comprises:

Generating a ranging signal for flip-chip MICRO LED chips;

Transmitting laser according to the ranging signal;

Performing phase modulation on laser based on a phase modulator to generate positive and negative frequency sidebands, and generating a target optical signal related to the free spectral range of an optical filter after the modulated laser signal passes through the optical filter;

Measuring a time difference between the emission and return of the target optical signal; and determining the first thickness of the flip-chip MICRO LED chip according to the time difference and the light speed information.

8. The method of bonding a flip-chip MICRO LED chip to a substrate of claim 1, further comprising, prior to securing the flip-chip MICRO LED chip to the substrate based on the optimized bond head:

Acquiring a scene image of the upper surface of the substrate;

preprocessing the scene image to obtain a preprocessed image;

Processing the preprocessed image based on a Gaussian Laplace function with 0 as a center and a Gaussian standard deviation sigma, determining discrete points and removing the discrete points to obtain a target image;

carrying out graying treatment and region division on the target image, and determining a plurality of local regions;

Determining the absolute value of the difference value between the gray value of each pixel point in each local area and the gray value of each adjacent pixel point, taking the maximum absolute value as the flat value of the corresponding pixel point, and judging whether the maximum absolute value is in a preset flat value range;

Calculating the ratio of the number of pixel points with the flat value not in the preset flat value range in each local area to the total pixel points in the local area, and judging whether the ratio is larger than the preset ratio;

and when the determined ratio is larger than the preset ratio, determining the corresponding local area as the area to be processed, and carrying out planarization processing on the area to be processed.

9. The method of bonding a flip-chip MICRO LED chip to a substrate of claim 8, wherein the preprocessing includes image noise reduction and image enhancement processing.