An efficient and high-quality microscale metal electrodeposition method

Abstract

A highly efficient and high-quality microscale metal electrodeposition method is designed to solve the problem that it is difficult to achieve highly efficient and high-quality microscale metal electrodeposition in the process of picking up metal microcomponents based on electrochemical deposition. First, through force analysis, the minimum height of the microscale metal required to be deposited for reliable pickup of electrochemical metal microcomponents is calculated; then, COMSOL simulation is used to analyze the influencing factors of microscale metal electrodeposition, and the efficient and high-quality electrodeposition parameter range is obtained; secondly, based on the back propagation neural network (BP), the relationship between the influencing factors and the microscale metal electrodeposition rate is established; finally, with the determined electrodeposition rate as the target value, a genetic algorithm is used to optimize the process parameters of microscale electrodeposition, and experimental verification is performed to achieve highly efficient and high-quality deposition. The present invention is suitable for microscale metal electrodeposition.

Description

Technical Field

[0001] The invention belongs to micro-nano operation, and in particular relates to an efficient and high-quality microscale metal electrodeposition method. Background Art

[0002] The picking technology of micro-components plays an important role in the assembly of complex systems at the micro / nano scale. The picking operation of metal micro-components based on electrochemistry is a reliable and non-destructive method. However, during the picking process, deposition first occurs in the microscale area between the manipulating tool and the operating object. Therefore, the quality and efficiency of microscale metal electrodeposition determine the success rate of subsequent operations. The quality and efficiency of microscale metal electrodeposition are affected by the electrolyte concentration, voltage and relative humidity of the environment, and it is difficult to achieve high-efficiency and high-quality deposition. In view of the above problems, the present invention proposes an efficient and high-quality microscale metal electrodeposition method. Summary of the invention

[0003] The present invention aims to solve the problem that it is difficult to achieve efficient and high-quality microscale metal electrodeposition in the process of picking up metal micro-components based on electrochemical deposition, and proposes an efficient and high-quality microscale metal electrodeposition method, which is carried out according to the following steps:

[0004] Step 1: Based on the force analysis, calculate the minimum height of the deposited microscale metal required to achieve reliable pickup of the electrochemical-based metal micro-component:

[0005]

[0006] In formula (1), F VDW is the van der Waals force per unit length between the micro-wire and the base, A H is the Hamaker constant, R is the radius of the metal wire, in m, and d is the distance between the micro-metal wire and the base, in m;

[0007]

[0008] In formula (2), δ Cu is the shear strength of the deposited micrometal, in MPa, l is the length of the micro-copper wire of the picked-up metal microcomponent, in m, r' is the radius of the deposited copper in the micropipette, in m, r Nozzle is the radius of the pipette nozzle, in m;

[0009] Δr=r'-r Noozle , (3)

[0010] According to the shape of the pipette nozzle, the relationship between the height of the deposited metal in the nozzle and Δr is obtained:

[0011] h=0.0639Δr3 -0.1794Δr 2 +0.2569Δr-0.0094, (4)

[0012] In formula (4), h is the height of the microscale metal electrodeposition in the pipette, in m;

[0013] Step 2: Use COMSOL simulation to analyze the effects of ambient relative humidity, electrolyte concentration, and applied deposition voltage on the rate and quality of microscale metal electrodeposition, and obtain a suitable parameter range;

[0014] Step 3: Based on the back propagation neural network (BP), the relationship between the influencing factors and the microscale metal electrodeposition rate is established. Taking the determined electrodeposition rate as the target value, the genetic algorithm is used to optimize the process parameters of microscale electrodeposition;

[0015] Step 4: 5×10 -8 The deposition rate of m / s was taken as the target parameter of the genetic algorithm. The optimized parameters were used for experimental verification to achieve high-efficiency and high-quality microscale metal electrodeposition.

[0016] As a further illustration of the efficient and high-quality microscale metal electrodeposition method described in the present invention, the COMSOL electrodeposition module is used for simulation in step 2, and the parameter ranges for efficient and high-quality microscale metal electrodeposition are: relative ambient humidity 50%-60%, electrolyte concentration 0.400mol / L-0.600mol / L, and applied voltage 0.15V-0.25V.

[0017] As a further illustration of the efficient and high-quality microscale metal electrodeposition method described in the present invention, the BP neural network in step 3 adopts a 2-5-1 structure, 200 sets of simulation data are used as input and output sample data of the neural network model, 20 sets of data are randomly selected as test sample data, and the remaining 180 sets of data are used as training sample data of the network model. The population size of the genetic algorithm is set to 40, the crossover probability is set to 0.4, the mutation probability is set to 0.2, and the number of iterative optimizations is set to 100.

[0018] The principle of the present invention is:

[0019] The quality and efficiency of the microscale metal deposited between the micropipette of the operating tool and the micro-copper wire of the operating object are the premise and key to the successful electrochemical metal microcomponent picking operation. First, through force analysis, the minimum height of the microscale metal deposited to achieve reliable pickup of metal microcomponents based on electrochemistry is calculated; then, COMSOL simulation is used to analyze the influencing factors of electrodeposition, and the parameter range of efficient and high-quality electrodeposition is obtained; secondly, based on the back propagation neural network (BP), the relationship between the influencing factors and the microscale metal electrodeposition rate is established; finally, with the determined electrodeposition rate as the target value, the genetic algorithm is used to optimize the process parameters of microscale electrodeposition, and experimental verification is carried out to achieve efficient and high-quality microscale metal electrodeposition.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] 1. Conventional microscale metal electrodeposition research requires a large number of experiments. Before the experiment, the present invention uses COMSOL to simulate the micro-metal electrodeposition process, analyzes the main influencing factors of electrodeposition, provides guidance for later experiments, improves the success rate of later experiments, and reduces material loss;

[0022] 2. Based on the back propagation neural network (BP), the relationship between the influencing factors and the microscale metal electrodeposition rate was established. The determined electrodeposition rate was taken as the target value, and the genetic algorithm was used to optimize the process parameters of microscale electrodeposition, achieving high-efficiency and high-quality microscale metal electrodeposition;

[0023] 3. It provides a strong guarantee for the reliable picking operation of metal micro-components based on electrochemistry. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Flow chart of an efficient and high-quality microscale metal electrodeposition method. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail in conjunction with the following embodiments. In this embodiment, an efficient and high-quality microscale metal electrodeposition method is carried out according to the following steps:

[0026] Step 1: Based on the force analysis, calculate the minimum height of the deposited microscale metal required to achieve reliable pickup of the electrochemical-based metal micro-component:

[0027]

[0028] In formula (1), F VDW is the van der Waals force per unit length between the micro-wire and the base, AH is the Hamaker constant, which is 1*10 -19 JR is the radius of the metal wire, which is 40*10 -6 m,d is the distance between the micro-metal wire and the base, which is 2*10 -10 m.

[0029]

[0030] In formula (2), δ Cu is the shear strength of the deposited micro-metal, which is 110Mpa, l is the length of the micro-copper wire of the picked-up metal micro-component, which is 600*10 -6 m, r N ozzle is the radius of the pipette nozzle, which is 10*10 -6 m, r' is the radius of the copper deposited in the micropipette, and r' is calculated by formula (2) to be 16.478*10 -6 m;

[0031] Δr=r'-r Noozle , (3)

[0032] According to the shape of the pipette nozzle, the relationship between the height of the microscale metal electrodeposition in the pipette and Δr is obtained:

[0033] h=0.0639Δr 3 -0.1794Δr 2 +0.2569Δr-0.0094, (4)

[0034] In formula (3), h = 11.497 × 10 -6 m, in order to make the picking more reliable, h = 12 × 10 -6 m.

[0035] Step 2: Use COMSOL simulation to analyze the effects of ambient relative humidity, electrolyte concentration, and applied deposition voltage on the rate and quality of microscale metal electrodeposition, and obtain a suitable parameter range.

[0036] The evaporation of water molecules in the microscale will affect the electrolyte concentration at the tip of the pipette and produce convection, thereby affecting the flow of ions to the cathode. The relative humidity of the environment determines the growth rate and geometric uniformity of the deposited microstructure. Through finite element analysis and modeling, a two-dimensional diffusion model of water evaporation in the pipette nozzle attachment was established in COMSOL. Dirichlet boundary conditions were selected for the pipette nozzle and the main area nearby. The relative humidity of the environment at the pipette opening was set to 100%, and the relative humidity of the surrounding main area was set to 30% to 80% to study the effect of relative humidity on microscale electrodeposition. In a microscale environment with too low relative humidity, the evaporation of the electrolyte can easily lead to the formation of microcrystals at the pipette nozzle, thereby blocking the pipette and preventing further deposition. If the humidity is too high, water will condense on the tip of the micropipette and the surface of the metal microcomponent. Thereby diluting the electrolyte in the curved liquid surface and affecting the electrodeposition process. Therefore, the relative humidity of the environment should be set at 50-60% to meet the requirements of deposition efficiency and quality.

[0037] The COMSOL electrochemical module defines microscale metal electrodeposition as a physical field constraint. A potential load is applied on the cathode substrate and the anode surface as a load constraint, and a boundary constraint is added at each boundary to simulate the effect of voltage and electrolyte concentration on micro-meniscus electrodeposition. The electrolyte concentration is kept at 0.500mol / L, and the voltage range is 0.05V to 0.35V. As the voltage increases, the electrical mobility and charge conversion rate increase, so the deposition rate increases with the increase in voltage. The simulation results show that from 0.05V to 0.25V, the deposition rate naturally increases with the voltage, but when the voltage exceeds 0.25V, the deposition rate increases slowly. In addition, too high a voltage can easily cause uneven copper deposition and hydrogen reduction reaction, resulting in a higher deposition rate at the edge than in the center, resulting in bubbles. Therefore, high voltage is not conducive to the quality of deposited copper. Therefore, the appropriate voltage in the experiment is 0.15-0.25V, which can obtain a higher deposition rate and quality. The electrolyte concentration is 0.2-0.8mol / L, and the anode load voltage is 0.20V. High concentration is the main choice for efficient deposition. However, when the electrolyte concentration is too high, crystal precipitation and pipette nozzle clogging are likely to occur due to the evaporation of water. Low concentration electrolyte can alleviate the clogging problem. However, when the electrolyte concentration is too low, the electrodeposition rate is also too low, and the deposition time will increase. Moreover, low electrolyte concentration can easily cause the appearance of metal ion deficiency areas. Therefore, in order to meet the requirements of high efficiency and non-clogging of the pipette during operation, the electrolyte concentration should be set to 0.400-0.600 mol / L.

[0038] Step three: Based on the back propagation neural network (BP), the relationship between the influencing factors and the microscale metal electrodeposition rate is established. After analyzing the influencing factors, since the relative humidity of the environment is not the main factor affecting the deposition rate, it is set to 50%. Voltage and electrolyte concentration are selected as the two main factors affecting the input value of the neural network model. The upper and lower limits of the voltage are defined as 0.15-0.25V, and the upper and lower limits of the electrolyte concentration are defined as 0.400-0.600mol / L. The BP neural network structure is 2-5-1, and 200 sets of simulation data are used as input and output sample data of the neural network model. 20 sets of data are randomly selected as test sample data, and the remaining data are used as network model training sample data. The genetic algorithm is used to optimize the process parameters of microscale electrodeposition, with 5×10 -8 The deposition rate of m / s is the target parameter of the genetic algorithm, and the upper and lower boundaries of voltage and electrolyte concentration are set. The size of the genetic algorithm group is set to 40, the crossover probability is set to 0.4, and the mutation probability is set to 0.2. The number of generations of iterative optimization is set to 100. After 100 generations, the convergence condition is met and a satisfactory optimization result is obtained.

[0039] Step 4: When the target deposition rate is 5×10 -8 m / s. After parameter optimization, the optimal voltage was 0.22V and the optimal electrolyte concentration was 0.550mol / L. The optimized parameters were used for experimental verification. After 240s, the height of the micro-metal deposited in the pipette was measured to be 12×10 -6 m, and the quality of microscale metal electrodeposition is good, achieving high-efficiency and high-quality microscale metal electrodeposition.

Claims

1. An efficient and high-quality microscale metal electrodeposition method, characterized in that: The method proceeds as follows: Step 1: Based on the force analysis, calculate the minimum height of the deposited microscale metal required to achieve reliable pickup of the electrochemical-based metal micro-component: In formula (1), F VDW is the van der Waals force per unit length between the micro-wire and the base, δ Cu is the shear strength of the deposited micrometal, in MPa, l is the length of the micro-copper wire of the picked-up metal microcomponent, in m, r' is the radius of the deposited copper in the micropipette, in m, r Nozzle is the radius of the pipette nozzle, in m; Δr=r'-r Noozle , (2) According to the shape of the pipette nozzle, the relationship between the height h of the deposited metal in the nozzle and Δr is obtained: h=0.0639Δr 3 -0.1794Δr 2 +0.2569Δr-0.0094, (3) In formula (3), h is the height of the microscale metal electrodeposition in the pipette, in m; Step 2: Use COMSOL simulation to analyze the effects of ambient relative humidity, electrolyte concentration, and applied deposition voltage on the rate and quality of microscale metal electrodeposition, and obtain a suitable parameter range; Step 3: Based on the back propagation neural network (BP), the relationship between the influencing factors and the microscale metal electrodeposition rate is established, and the determined electrodeposition rate is taken as the target value, and the process parameters of the microscale electrodeposition are optimized by using a genetic algorithm; Step 4: Use the optimized parameters to conduct experimental verification to achieve high-efficiency and high-quality microscale metal electrodeposition.

2. A highly efficient and high-quality microscale metal electrodeposition method as claimed in claim 1, characterized in that: Using COMSOL electrodeposition module for simulation, it was found that the parameter ranges for efficient and high-quality microscale metal electrodeposition are: relative ambient humidity 50%-60%, electrolyte concentration 0.400mol / L-0.600mol / L, and applied voltage 0.15V-0.25V.

3. A highly efficient and high-quality microscale metal electrodeposition method as claimed in claim 1, characterized in that: The BP neural network adopts a 2-5-1 structure. 200 sets of simulated data are used as the input and output sample data of the neural network model. 20 sets of data are randomly selected as test sample data, and the remaining 180 sets of data are used as training sample data of the network model. The population size of the genetic algorithm is set to 40, the crossover probability is set to 0.4, the mutation probability is set to 0.2, and the number of iterative optimization is set to 100.

4. The method of efficient and high-quality microscale metal electrodeposition according to claim 1, characterized in that: 5×10 -8 The m / s deposition speed was the target parameter of the genetic algorithm, and the optimized parameters were used for experimental verification to achieve high-efficiency and high-quality microscale metal electrodeposition.

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