An Expandable Topological Flow Channel and Its Design Method

Abstract

The present invention discloses an expandable topological flow channel with high-throughput heat dissipation and its design method. The flow channel includes: a large inlet structure, a large diffusion structure, and a large outlet structure; the large inlet structure is an inlet for large-area liquid inlet; the topological micro-channel of the large diffusion structure is a three-stage type, including: a front section, a middle section, and a rear section; the fins of the front section introduce the flowing cooling working medium from the secondary channels of the front section to both sides, and cooperate with the first middle fin of the main channel of the front section to make the cooling working medium approach the middle, and the main channel of the front section gradually narrows; the second middle fin of the middle section divides the cooling working medium in the main channel of the front section into first edge fluids, and the first edge fluids gather towards the middle under the influence of the fins of the middle section and are divided into second edge fluids by the shunt fins of the middle section; the second edge fluids converge in the rear section, and the third middle fin of the rear section is used to increase the heat exchange area; the large outlet structure is an outlet for large-area liquid outlet.

Description

Technical Field

[0001] The present invention belongs to the technical field of chip thermal management, and particularly relates to an expandable topological flow channel and a design method thereof. Background Art

[0002] With the development of integrated circuit fabrication and chip packaging technologies and the demand for higher computing power chips, the number of transistors in a chip per unit area has increased significantly, resulting in a rapid rise in the chip power density. The local heat flux density can reach 1000 W / cm 2 ². During the operation of the chip, the temperature continuously increases. If rapid heat dissipation cannot be achieved, it will increase the chip power consumption, limit the multi-core operating frequency of the chip, accelerate chip aging, and seriously lead to chip failure or even burnout. Research shows that more than 95% of the space in an electronic chip is used for heat dissipation, and the temperature of a continuously operating electronic chip should not exceed 85 °C. With the further improvement of chip integration, higher requirements for heat dissipation are put forward, and the further development of chip technology requires more advanced thermal management technology as support.

[0003] Currently, the research on chip microchannel heat dissipation methods focuses on manifold microchannels, jet microchannels, and patch-type external microchannels, etc. Although these heat dissipation methods show relatively strong heat dissipation performance, there are still many deficiencies, such as poor stability of working fluid flow, uneven heat transfer leading to the generation of local hot spots, etc., which restrict the further improvement of the chip heat dissipation level.

[0004] Traditional chip microchannel heat dissipation adopts a parallel structure of multiple horizontal microchannels. It has low processing accuracy requirements and is not easily blocked. However, it also has disadvantages such as unstable flow, poor thermal uniformity, high pump power, etc. There is a large flow difference between different flow channels, and the fluid flow rate in the central flow channel is much higher than that in the edge flow channels. The long flow path leads to a large pressure drop, and the mismatch between the pressure gradient and the temperature gradient results in low heat transfer efficiency, etc. With the increasing heat flux density due to the improvement of chip computing power, the heat dissipation capacity of traditional straight microchannels can no longer match, which has restricted the further development of chip microchannel heat dissipation. As an emerging microchannel design method, the optimization of topological microchannel structures has emerged as the times require.

[0005] Compared with traditional straight microchannels, the flow stability and thermal uniformity of topological microchannels are greatly improved, and it has gradually become an important means to solve the heat dissipation of high-power density chips. The topological microchannel structure realizes the optimization of the microchannel structure based on fluid mechanics, structural mechanics, and fractal geometry, etc. It can reduce the flow resistance of the working fluid and the heat transfer resistance, improve the flow stability and thermal uniformity, and significantly enhance the heat dissipation performance of the microchannel, especially suitable for the heat dissipation of large-size high-heat flux density chips. With the continuous development of lithography technology and microchannel fine processing technology, it has become possible to directly construct topological microchannels on the chip substrate, which can further improve the heat dissipation capacity of chip microchannels.

[0006] Traditional topology channel designs for large-scale heat dissipation often feature a form of "small inlet - large diffusion - small outlet", while in the actual heat dissipation process of chips, it is mainly "large inlet - large diffusion - large outlet". The traditional large-area topology channel design method deviates from the actual heat dissipation conditions. In addition, there are large dead zones at the corners of traditional topology channel designs, which are prone to heat accumulation and cause hot spots. There are also disadvantages such as long calculation time and easy blockage in the pursuit of fine bionic structures, resulting in low practical application value. Summary of the Invention

[0007] The present invention aims to solve the deficiencies of the prior art and provides the following solutions:

[0008] An expandable topology flow channel, comprising: a large inlet structure, a large diffusion structure, and a large outlet structure;

[0009] The large inlet structure is an inlet for large-area liquid inflow;

[0010] The topology microchannel of the large diffusion structure is a three-stage type, comprising: a front stage, a middle stage, and a rear stage;

[0011] The front stage includes a first axial fin and 5 first middle fins. The front stage starts from the first axial fin, the first axial fin is arranged on the first symmetry axis, the 5 first middle fins are arranged in sequence and approach the second symmetry axis, and there are gaps between the first axial fin and the 5 first middle fins; the fins of the front stage introduce the inflowing cooling working medium from the secondary channels of the front stage to both sides, and cooperate with the first middle fins of the main channel of the front stage to make the cooling working medium approach the middle, and the main channel of the front stage gradually narrows;

[0012] The middle stage includes a second axial fin, a third axial fin, a fourth axial fin, and 3 second middle fins. The middle stage starts from the third axial fin, the third axial fin is arranged on the second symmetry axis, the 3 second middle fins are arranged in sequence and approach the first symmetry axis, reaching the second axial fin on the first symmetry axis, and at the same time, the fourth axial fin is arranged at the end position of the middle stage. There are gaps between the second axial fin, the third axial fin, the fourth axial fin, and the 3 second middle fins; the second middle fins of the middle stage divide the cooling working medium in the main channel of the front stage into a first edge fluid, and the first edge fluid gathers towards the middle under the influence of the fins of the middle stage and is divided into a second edge fluid by the shunt fins of the middle stage;

[0013] The rear section includes three third middle fins. The three third middle fins are arranged in sequence starting from the second axial fin and approach the second symmetry axis. There are gaps between the three third middle fins. The second edge fluid converges in the rear section, and the third middle fins in the rear section are used to increase the heat exchange area.

[0014] The large outlet structure is an outlet for large-area liquid discharge.

[0015] The present invention also provides a design method for an expandable topological flow channel. The design method is used to design the above-mentioned expandable topological flow channel and includes the following steps:

[0016] According to the actual working environment of the chip radiator, establish a double-plane pseudo-three-dimensional topology optimization model, and obtain the physical parameters, heat source distribution, and cooling working medium parameters of the chip radiator;

[0017] Determine the chip working temperature, cooling working medium boundary conditions, and heat source description form. Based on the physical parameters, heat source distribution, and cooling working medium parameters of the chip radiator, determine the basic method of the topology optimization problem, and construct a topology optimization mathematical model by setting the topology optimization objective function;

[0018] Perform finite element mesh division on the three-dimensional topology optimization model and the topology optimization mathematical model, initialize the relevant physical fields of the model, calculate to obtain the topology optimization model, and perform parameter iteration on the topology optimization model to obtain the final topology optimization model;

[0019] Based on the final topology optimization model, use the spline function for fitting to obtain a topology optimization two-dimensional model, and perform symmetric expansion on the topology optimization two-dimensional model to obtain the expandable topological flow channel.

[0020] Preferably, the physical parameters include: radiator width W = 0.5 - 3 mm, radiator length L 2 = 5 - 20 mm, radiator thickness z = 0.1 - 1 mm, radiator inlet length L in = 0.5 - 2 mm, radiator outlet length L out = 0.5 - 2 mm, the material of the radiator, the thermal conductivity k of the radiator material s and the specific heat capacity at constant pressure C of the radiator material p,s and the density ρ of the radiator material s ;

[0021] The heat source distribution includes: the heat source position is the α 1 plane, and the application direction is from the α 1 plane to conduct vertically to the α 2 plane;

[0022] The parameters of the cooling working fluid include: the composition of the cooling working fluid, the thermal conductivity k of the cooling working fluid f , the specific heat capacity at constant pressure C of the cooling working fluid p,f and the density ρ of the cooling working fluid f .

[0023] Preferably, the boundary conditions of the cooling working fluid include: the inlet pressure p in = 10 - 200 Pa, the outlet pressure p out = 0 Pa, and the inlet temperature T in = 293.15 - 313.15 K;

[0024] The description form of the heat source is:

[0025] F = h e (1 - γ)(T s - T)

[0026] where F represents the total heat transfer amount in the design domain, h e represents the heat transfer coefficient of the fins on the α 1 plane, γ represents the topological optimization design variable, T s represents the chip operating temperature, and T represents the temperature in the design domain.

[0027] Preferably, the method for constructing the topological optimization mathematical model includes:

[0028] Based on the physical parameters of the chip radiator, the heat source distribution, and the parameters of the cooling working fluid, the laminar flow and fluid heat transfer physical fields are added to the pseudo-three-dimensional topological optimization model by using the variable density method, and the properties in the virtual solid-liquid mixed state in the design domain are defined through the material interpolation equation model:

[0029]

[0030] where α(γ) represents the resistance term coefficient, α f represents the reverse osmosis rate in the fluid domain, α s represents the reverse osmosis rate in the solid domain, ρ(γ) represents the density of the virtual solid-liquid state in the domain, C p (γ) represents the heat capacity of the virtual solid-liquid state in the domain, k(γ) represents the density thermal conductivity of the virtual solid-liquid state in the domain, q, q ρ , q Cp and q k represent the optimization parameters, μ in represents the inlet fluid viscosity, and Da represents the Darcy number;

[0031] Set the total heat transfer amount F in the design domain as the topological optimization objective function;

[0032] Set the constraint solid phase fraction and construct the topological optimization mathematical model:

[0033]

[0034]

[0035] Among them, Ψ represents the topology optimization design domain, V Ψ is the volume of the topology optimization design domain, V s represents the set liquid fraction, p represents the pressure, u represents the fluid velocity in the x - direction, v represents the fluid velocity in the y - direction, and μ represents the dynamic viscosity of the fluid.

[0036] Preferably, the method for obtaining the final topology optimization model includes:

[0037] Perform finite - element mesh division on the three - dimensional topology optimization model and the topology optimization mathematical model, and use the Helmholtz filter to solve the mesh - independence and checkerboard problems generated:

[0038]

[0039] Among them, represents the auxiliary function after the topology optimization design variable γ is filtered by the Helmholtz filter, represents the Hamiltonian operator, r m represents the filtering parameter, represents the function after β γ is projected by hyperbolic tangent, and γ represents the optimization parameter;

[0040] Use the optimization iteration algorithm to continuously process the filtering function through the optimization parameters q, γ β and Da, set the maximum number of iteration steps and the iteration termination condition for each step, optimize the topology optimization objective function, and initialize the density field, temperature field, and velocity field of the model to obtain the topology optimization model;

[0041] Use the topology optimization model as the initial value, set the optimization parameters to solve for the next topology optimization model until the final convergence requirement is met to complete the entire continuous optimization process, and output the final topology optimization model.

[0042] Preferably, the method for obtaining the extensible topology flow channel includes:

[0043] Fit the final topology optimization model using the B - spline function to obtain the fitted two - dimensional topology optimization model;

[0044] Using the setting of bilateral symmetry in the boundary conditions for the topological optimization two-dimensional model, taking the bilateral symmetric boundaries as the symmetry axes, performing symmetric expansion multiple times, deleting the overlapping original symmetric condition boundaries, and converting the remaining symmetric boundary conditions into internal boundary conditions to obtain the expandable topological flow channel.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] Based on the variable density topological optimization method, the present invention makes the optimized model match the actual heat dissipation process by correction and reasonably designs the optimization boundary conditions to make it expandable. Under the combined action, it avoids the poor thermal conductivity at the corners in the traditional topological optimization mode. The topological channels designed by this method significantly improve the heat dissipation capacity, solve the problems of mismatch between the traditional topological optimization and the actual heat dissipation process, easy generation of local hot spots in local dead zones, and poor expandability. At the same time, the expandability is applicable to the actual preparation of heat sinks for large-size chips, significantly improving the heat exchange capacity compared with straight channels, and actually using laser etching for processing and preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0048] Figure 1 It is a schematic structural diagram of one of the expandable topological flow channels in the embodiment of the present invention;

[0049] Figure 2 It is a schematic structural diagram of the large diffusion structure in the expandable topological flow channel structure of the embodiment of the present invention;

[0050] Figure 3 It is a schematic flowchart of the method in the embodiment of the present invention;

[0051] Figure 4 It is a schematic structural diagram of the double-plane pseudo-three-dimensional topological optimization model in the embodiment of the present invention;

[0052] Figure 5 It is a schematic structural diagram of the large-size chip heat sink model in the embodiment of the present invention;

[0053] Figure 6 It is a typical silicon-embedded expandable topological channel obtained by laser etching in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0055] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0056] Embodiment 1

[0057] In this embodiment, as Figure 1 、 Figure 2 shown, a scalable topological flow channel includes: a large inlet structure, a large diffusion structure, and a large outlet structure.

[0058] The large inlet structure is an inlet for large-area liquid inlet.

[0059] The topological microchannel of the large diffusion structure is of a three-stage type, including: a front stage, a middle stage, and a rear stage; the front stage includes a first axial fin and 5 first middle fins. The front stage starts from the first axial fin, and the first axial fin is arranged on the first symmetry axis. The 5 first middle fins are arranged in sequence and approach the second symmetry axis. There are gaps between the first axial fin and the 5 first middle fins; the fins in the front stage introduce the inflowing cooling working medium from the secondary channels in the front stage to both sides, and cooperate with the first middle fins in the main channel of the front stage to move the cooling working medium closer to the middle. The main channel in the front stage gradually narrows; the middle stage includes a second axial fin, a third axial fin, a fourth axial fin, and 3 second middle fins. The middle stage starts from the third axial fin, and the third axial fin is arranged on the second symmetry axis. The 3 second middle fins are arranged in sequence and approach the first symmetry axis to reach the second axial fin on the first symmetry axis. At the same time, a fourth axial fin is arranged at the end position of the middle stage. There are gaps between the second axial fin, the third axial fin, the fourth axial fin, and the 3 second middle fins; the second middle fins in the middle stage divide the cooling working medium in the main channel of the front stage into a first edge fluid, and the first edge fluid gathers towards the middle under the influence of the fins in the middle stage and is divided into a second edge fluid by the shunt fins in the middle stage; the rear stage includes 3 third middle fins, and the 3 third middle fins are arranged in sequence and approach the second symmetry axis starting from the second axial fin. There are gaps between the 3 third middle fins; the second edge fluid converges in the rear stage, and the third middle fins in the rear stage are used to increase the heat exchange area.

[0060] In this embodiment, the spacing between the fins is 0.1 - 0.2 mm. The spacing between the fins on the shaft and the middle fins is relatively large. The three sections of fins are evenly distributed transversely along the flow path. The length of each fin is about 0.5 mm. When the middle fins approach the fins on the shaft, the area will increase significantly. Vertically, they approach the two side symmetry axes in a stepped manner, and the spacing between the fins is similar. At the front end, a larger number of fins are arranged to increase the number of secondary channels and slow down the liquid distribution flow rate, making the liquid distribution more uniform. The fins in the middle and rear sections mainly play a role in disturbing the fluid.

[0061] The channels formed between the fins on the shaft and the middle fins are the main channels, that is, the channels with a larger width along the flow path direction are the main channels, and there are 2 in total; the channels formed between the middle fins are the secondary channels, that is, the channels with a narrower width perpendicular to the flow path direction are the secondary channels, and there are 9 in total. The main channels and the secondary channels are basically perpendicular to each other. The first 5 middle fins in the front section form 4 secondary channels, which are evenly distributed transversely and tend to narrow along the flow path; the 3 second middle fins in the middle section form 2 secondary channels with similar widths; the 3 third middle fins in the rear section are formed with similar widths; after the multi-fin diversion, it finally presents a shape with multiple secondary channels evenly distributed between the two main channels. The main channels and the secondary channels intersect with each other to realize the overall flow process of liquid distribution - multi-liquid diversion - outflow.

[0062] The large outlet structure is an outlet for large-area liquid outflow.

[0063] In this embodiment, in the overall model setting of "large inlet - large diffusion - large outlet", it conforms to the current actual chip heat dissipation method. "Large inlet" refers to the large inlet structure, whose inlet area for liquid inflow is large. As a result, at the same flow rate, the cooling working medium has a larger flow rate, the liquid distribution is more uniform, and the heat dissipation capacity and temperature uniformity of the cooling working medium can be significantly improved.

[0064] "Large diffusion" and the large diffusion structure mean that the process area for the cooling working medium to flow and exchange heat within the design domain is large, and the fluid can fully carry out the flow and heat transfer process within the domain, such as Figure 2As shown, it is a topological microchannel expanded symmetrically about the second axis of symmetry. The topological microchannel formed within the domain is divided into three segments, including a front segment, a middle segment, and a rear segment. The front fins introduce the central fluid from the secondary channels to both sides, and cooperate with the first middle fins in the main channel to move towards the middle. The secondary channels achieve a more uniform large-area liquid distribution; in the middle segment, the central liquid is further divided into the first edge liquid by the second middle fins in the middle. At the same time, the liquid on the edge side tends to gather towards the middle more, and convects with each other to form local vortices, strengthening the disturbance between fluids. The two parts of the liquid are fully mixed. The larger-sized main channel speeds up the fluid flow rate. At the same time, the second middle fins in the middle segment also introduce some central fluid into the second edge fluid. The second edge fluid converges in the rear segment. At the same time, the fins increase the convective heat transfer area, preventing the temperature of the edge fluid in the rear segment from rising, forming a basic process of uniform liquid distribution in the front segment, strengthening the mixing and disturbance between the central fluid and the edge fluid in the middle segment, and rapid outflow and further strengthening of the disturbance in the rear segment, which perfectly fits the large-size chip heat dissipation problem targeted by the proposal.

[0065] "Large outlet" refers to the large outlet structure, which has a large outlet area, speeds up the flow process of the fluid working medium, and at the same time reduces the pressure drop at the outlet part, avoiding the problem of local countercurrent before the "small outlet".

[0066] Embodiment 2

[0067] In this embodiment, as Figure 3 shown, a design method for an expandable topological channel includes the following steps:

[0068] S1. According to the actual working environment of the chip radiator, establish a double-plane pseudo-three-dimensional topological optimization model, and obtain the physical parameters, heat source distribution, and cooling working medium parameters of the chip radiator.

[0069] In this embodiment, first construct a physical model of the radiator and simplify it into a double-plane pseudo-three-dimensional topological optimization model, as Figure 4 shown, including the α 1 plane and the α 2 plane. Among them, the α 1 plane is regarded as the bottom plane of the radiator, and the α 2 plane is regarded as the middle cross-section of the chip radiator.

[0070] The physical parameters include: the width of the radiator W = 0.5 - 3 mm, the length of the radiator L 2 = 5 - 20 mm, the thickness of the radiator z = 0.1 - 1 mm, the inlet length of the radiator L in = 0.5 - 2 mm, the outlet length of the radiator L out = 0.5 - 2 mm, the material of the radiator, the thermal conductivity k s of the radiator material, the specific heat capacity at constant pressure C p,s of the radiator material, and the density ρs , in this embodiment, the radiator material can be copper or silicon; the heat source distribution includes: the heat source position is the α 1 plane, and the application direction is from α 1 plane and conducts vertically to the α 2 plane; the coolant parameters include: the coolant composition, the thermal conductivity k of the coolant f , the specific heat capacity C at constant pressure of the coolant p,f and the density ρ of the coolant f , in this embodiment, the coolant is water, acetone, HFE-7100, ethanol.

[0071] S2. Determine the chip operating temperature, the coolant boundary conditions, and the heat source description form. Based on the physical parameters of the chip radiator, the heat source distribution, and the coolant parameters, determine the basic method of the topology optimization problem, and construct a topology optimization mathematical model by setting the topology optimization objective function.

[0072] The coolant boundary conditions include: the inlet pressure p in = 10 - 200 Pa, the outlet pressure p out = 0 Pa, and the inlet temperature T in = 293.15 - 313.15 K;

[0073] The heat source description form is the product of the fin heat transfer coefficient h 1 of the α plane and the solid phase fraction in the design domain, and then the product of the chip operating temperature T e and the difference between the design domain temperature T:

[0074] F = h e (1 - γ)(T s - T)

[0075] 0 ≤ γ ≤ 1

[0076] where F represents the total heat transfer in the design domain, h e represents the heat transfer coefficient of the fins of the α 1 plane, h e = 10 5 - 10 8 W / (m 3 ·K), γ represents the topology optimization design variable, T s represents the chip operating temperature, T s = 358.15 K, T represents the temperature in the design domain, 0 represents the heat dissipation material (solid domain), and 1 represents the coolant (fluid domain).

[0077] In this embodiment, the method for constructing the topology optimization mathematical model includes:

[0078] Based on the physical parameters of the chip radiator, the heat source distribution, and the cooling working fluid parameters, the laminar flow and fluid heat transfer physical fields are added to the pseudo-three-dimensional topology optimization model using the variable density method. The fluid flow is defined as incompressible flow, and only heat conduction and convective heat transfer are considered in the heat transfer process, while heat radiation and viscous dissipation of the fluid are not considered. A non-isothermal flow multi-physics field coupling interface is set up, and the properties ρ(γ), C p (γ), and k(γ) in the virtual solid-liquid mixed state within the design domain are defined through the material interpolation equation model:

[0079]

[0080] Among them, α(γ) represents the resistance term coefficient, α f represents the osmotic rejection rate in the fluid domain, α f = 0, α s represents the osmotic rejection rate in the solid domain, ρ(γ) represents the density of the virtual solid-liquid state within the domain, C p (γ) represents the heat capacity of the virtual solid-liquid state within the domain, k(γ) represents the thermal conductivity of the density of the virtual solid-liquid state within the domain, q, q ρ , q Cp and q k represent optimization parameters, set to 0.01 - 0.05, μ in represents the inlet fluid viscosity, Da represents the Darcy number, Da = 10 -6 ~10 -3 ;

[0081] The total heat transfer amount F within the design domain is set as the topology optimization objective function;

[0082] The solid phase fraction is set as a constraint, and a topology optimization mathematical model is constructed:

[0083]

[0084]

[0085] Among them, Ψ represents the topology optimization design domain, V Ψ is the volume of the topology optimization design domain, V s represents the set liquid phase fraction, V s = 0.1 - 0.5, p represents pressure, u represents the fluid velocity in the x direction, v represents the fluid velocity in the y direction, and μ represents the dynamic viscosity of the fluid.

[0086] S3. Perform finite element mesh division on the three-dimensional topology optimization model and the topology optimization mathematical model, initialize the relevant physical fields of the model, calculate to obtain the topology optimization model, and perform parameter iteration on the topology optimization model to obtain the final topology optimization model.

[0087] The method for obtaining the final topology optimization model includes:

[0088] Perform finite element mesh division on the three-dimensional topology optimization model and the topology optimization mathematical model, and use the Helmholtz filter to solve the generated mesh independence and checkerboard problems:

[0089]

[0090] Among them, represents the auxiliary function after the topology optimization design variable γ is filtered by the Helmholtz filter, represents the Hamiltonian operator, r m represents the filtering parameter, represents that is the function after the hyperbolic tangent projection of γ β represents the optimization parameter;

[0091] Use the optimization iteration algorithm to continuously process the filtering function through the optimization parameters q, γ β and Da, set the maximum number of iteration steps and the iteration termination condition for each step, optimize the topology optimization objective function, and initialize the density field, temperature field, and velocity field of the model to obtain the topology optimization model; in this embodiment, the moving asymptote algorithm MMA or SNOPT is selected as the optimization iteration algorithm, and the filtering function is continuously processed through the parameters q, γ β and Da, and different optimization parameter values are used for each step of the optimization process. Set the maximum number of iteration steps and the iteration termination condition for each step. When |F i+1 -F i |≤n, where F i is the objective function value obtained in the i-th iteration, i is the iteration step number, the maximum number of iteration steps is set to 100, n is the iteration convergence upper limit, and the parameter values are set as shown in Table 1:

[0092] Table 1

[0093]

[0094] Initialize the density field, temperature field, and velocity field of the model, and obtain the topology optimization model through the first-step calculation. Use the topology optimization model as the initial value, set the optimization parameters to solve for the next topology optimization model until the final convergence requirement is met to complete the entire continuous optimization process, and output the final topology optimization model.

[0095] S4. Based on the final topology optimization model, use the spline function for fitting to obtain the topology optimization two-dimensional model, and perform symmetric expansion on the topology optimization two-dimensional model to obtain the expandable topology flow channel.

[0096] In this embodiment, the method for obtaining the expandable topology flow channel includes:

[0097] Import the final topology optimization model into CAD, fit it using B-spline functions to obtain the optimized two-dimensional topology model after fitting; for the optimized two-dimensional topology model, utilize the bilateral symmetry setting in the boundary conditions, take the two-sided symmetric boundary as the axis of symmetry, repeat the symmetric expansion multiple times, delete the overlapping original symmetric boundary conditions, convert the remaining symmetric boundary conditions into internal boundary conditions to obtain an expandable topological flow channel, and then perform symmetric expansion on the expandable topological flow channel to obtain a large-size chip radiator model, as Figure 5 shown.

[0098] Then, import the expandable topological flow channel after fitting into the CFD software, set the physical properties of the fluid working medium and the solid material, and add relevant boundary conditions; set the heat source characteristics according to the boundary conditions, including the form of heat source action, heat source location, and heat source size, and set the characteristics of the fluid working medium, including the inlet temperature T in , inlet pressure p in , outlet pressure p out , to construct a fluid-solid coupling heat transfer simulation model; perform mesh division on the model, set the convergence conditions and the maximum number of iteration steps, and select the Simple solution method for solving. Then change the inlet pressure p in of the fluid working medium and the liquid phase fraction V s , and repeat the above steps to obtain multiple topological channels and the corresponding temperature fields and velocity fields, and calculate the relevant heat transfer data:

[0099]

[0100] T max = max(T 1 , T 2 ,..., T n )

[0101] where, R represents the thermal resistance, T w represents the cross-sectional temperature, T ave represents the average temperature, A represents the mesh surface of the contact surface between the fluid and the solid, T n represents the temperature data of the nth mesh, A n represents the area of the nth mesh, and N represents the number of meshes; based on the calculation results, compare with the straight channel, as shown in Table 2:

[0102] Table 2

[0103]

[0104] It can be seen from the table that the average temperature, the highest temperature, and the equivalent thermal resistance value of the topological channel are significantly lower than those of the straight channel. The average temperature of the topological channel is 27.54 K lower than that of the straight channel, the highest temperature is 13.41 K lower than that of the straight channel, and the thermal resistance is 0.737 K·cm lower than that of the straight channel 2 / W, the thermal resistance of the straight channel is 235.73% of that of the topological channel. It can be seen that the topologically optimized three-dimensional channel structure obtained by the method of the present invention is significantly superior to the traditional straight channel design in terms of heat dissipation capacity and temperature uniformity.

[0105] Example 3

[0106] In this embodiment, a method for preparing the expandable topological flow channel is also provided:

[0107] Import the expandable topological flow channel structure into CAD software, and draw according to the required channel area of 2 cm 2 Reserve the anodic bonding area, the liquid inlet and liquid distribution areas, and perform filling treatment on the areas to be etched to obtain a two-dimensional CAD pattern to be etched.

[0108] Determine relevant parameters such as the etching laser intensity, etching method, and etching time. The processing equipment is an ultraviolet laser marking machine. The nanosecond ultraviolet etching technology and vertical two-way etching are adopted. The laser intensity is 2 - 5 W, the pulse width is 1 ns, the pulse frequency is 40 KHz, the speed is 1000 mm / a, and the etching time is 1.5 h - 2.5 h.

[0109] Place a silicon wafer with an area of two inches and a thickness of 550 μm in the laser etching processing area, and etch according to the relevant set parameters to obtain a typical topological channel structure with a depth of 300 μm, as Figure 6 shown, which will be applied to the preparation of an actual chip radiator in the future.

Claims

1. An expandable topology flow channel, characterized in that: include: Large import structure, large diffusion structure and large export structure; The large inlet structure is an inlet for liquid inlet over a large area; The topological microfluidic channel of the large diffusion structure is a three-section type, including: a front section, a middle section and a rear section; The front section includes a first axial fin and five first middle fins. The front section starts from the first axial fin. The first axial fin is arranged on the first symmetry axis. The five first middle fins are arranged in sequence and close to the second symmetry axis. Gaps are provided between the first axial fin and the five first middle fins. The fins of the front section introduce the inflowing cooling medium from the front section secondary channel to both sides, and the first middle fins cooperate with the front section main channel to bring the cooling medium close to the middle. The front section main channel gradually narrows. The middle section includes a second axial fin, a third axial fin, a fourth axial fin and three second middle fins. The middle section starts from the third axial fin. The third axial fin is arranged on the second symmetry axis. The three second middle fins are arranged in sequence and approach the first symmetry axis to reach the second axial fin on the first symmetry axis. At the same time, the fourth axial fin is arranged at the end position of the middle section. Gaps are provided between the second axial fin, the third axial fin, the fourth axial fin and the three second middle fins. The second middle fin of the middle section divides the cooling medium in the main channel of the front section into a first edge fluid. The first edge fluid gathers toward the middle under the influence of the fins of the middle section and is divided into a second edge fluid by the diverter fins of the middle section. The rear section includes three third middle fins, which are arranged in sequence from the second axial fins and close to the second symmetry axis, and gaps are provided between the three third middle fins; the second edge fluid is collected in the rear section, and the heat exchange area is increased by using the third middle fins of the rear section; The large outlet structure is an outlet for discharging liquid over a large area.

2. A method for designing an expandable topological flow channel, the method for designing an expandable topological flow channel is used to design the expandable topological flow channel according to claim 1, characterized in that: The following steps are involved: According to the actual working environment of the chip heat sink, a dual-plane pseudo three-dimensional topology optimization model is established, and the physical parameters, heat source distribution and cooling medium parameters of the chip heat sink are obtained; Determine the chip operating temperature, cooling fluid boundary conditions and heat source description form, determine the basic method of topology optimization problem based on the physical parameters of the chip heat sink, the heat source distribution and the cooling fluid parameters, and construct a topology optimization mathematical model by setting the topology optimization objective function; Performing finite element meshing on the three-dimensional topology optimization model and the topology optimization mathematical model, initializing model-related physical fields, calculating to obtain a topology optimization model, and performing parameter iteration on the topology optimization model to obtain a final topology optimization model; Based on the final topology optimization model, a spline function is used to fit a topology optimization two-dimensional model, and the topology optimization two-dimensional model is symmetrically expanded to obtain the expandable topology flow channel.

3. A design method for an expandable topological flow channel according to claim 2, characterized in that: The physical parameters include: radiator width W = 0.5 ~ 3mm, radiator length L2 = 5 ~ 20mm, radiator thickness z = 0.1 ~ 1mm, radiator inlet length L in =0.5~2mm, radiator outlet length L out =0.5~2mm, radiator material, radiator material thermal conductivity k s , Radiator material constant pressure specific heat capacity C p,s and heat sink material density ρ s ; The heat source distribution includes: the heat source position is the α1 plane, and the application direction is vertically conducted from the α1 plane to the α2 plane; The cooling medium parameters include: cooling medium composition, cooling medium heat conduction coefficient k f , constant pressure specific heat capacity of cooling medium C p,f and cooling medium density ρ f .

4. A method for designing an expandable topological flow channel according to claim 3, characterized in that: The cooling medium boundary conditions include: inlet pressure p in =10~200Pa, outlet pressure p out =0Pa and inlet temperature T in =293.15~313.15K; The heat source description form is: F=h e (1-γ)(T s -T) Where F represents the total heat transfer in the design domain, h e represents the heat transfer coefficient of the fin in the α1 plane, γ represents the topology optimization design variable, T s represents the chip operating temperature, and T represents the temperature in the design domain.

5. A method for designing an expandable topological flow channel according to claim 4, characterized in that: The method for constructing the topology optimization mathematical model includes: Based on the physical parameters of the chip heat sink, the distribution of the heat source and the parameters of the cooling medium, the variable density method is used to add laminar flow and fluid heat transfer physical fields to the pseudo three-dimensional topology optimization model, and the properties of the virtual solid-liquid mixed state in the design domain are defined by the material interpolation equation model: Among them, α(γ) represents the resistance coefficient, α f represents the reverse permeability in the fluid domain, α s represents the reverse permeability in the solid domain, ρ(γ) represents the virtual solid-liquid state density in the domain, C p (γ) represents the heat capacity of the virtual solid-liquid state in the domain, k(γ) represents the density thermal conductivity of the virtual solid-liquid state in the domain, q, q ρ ,q Cp and q k represents the optimization parameter, μ in represents the inlet fluid viscosity, Da represents the Darcy number; Setting the total heat transfer F in the design domain as the topology optimization objective function; Set the constrained solid phase fraction and build the topology optimization mathematical model: Where Ψ represents the topology optimization design domain, V Ψ Design domain volume for topology optimization, V s represents the set liquid phase fraction, p represents the pressure, u represents the velocity of the fluid in the x direction, v represents the velocity of the fluid in the y direction, and μ represents the dynamic viscosity of the fluid.

6. A method for designing an expandable topological flow channel according to claim 5, characterized in that: The method for obtaining the final topology optimization model includes: Finite element meshing is performed on the three-dimensional topology optimization model and the topology optimization mathematical model, and the resulting mesh independence and checkerboard problems are solved using a Helmholtz filter: in, represents the auxiliary function after the topology optimization design variable γ is filtered by the Helmholtz filter, represents the Hamiltonian operator, r m Indicates the filtering parameters. Indicates that The function after hyperbolic tangent projection, γ β represents the optimization parameters; Using the optimization iterative algorithm, by optimizing the parameters q, γ β and Da perform continuous processing on the filter function, set the maximum number of iteration steps and the iteration termination condition of each step, optimize the topology optimization objective function, and initialize the density field, temperature field and velocity field of the model to obtain the topology optimization model; The topology optimization model is used as the initial value, and the optimization parameters are set to solve the next topology optimization model, until the final convergence requirement is reached to complete the entire continuous optimization process, and the final topology optimization model is output.

7. A method for designing an expandable topological flow channel according to claim 5, characterized in that: The method for obtaining the expandable topological flow channel includes: The final topology optimization model is fitted using a B-spline function to obtain a fitted topology optimization two-dimensional model; The topology optimization two-dimensional model uses the bilateral symmetry setting in the boundary conditions, takes the bilateral symmetric boundaries as the symmetry axis, repeats the symmetric expansion multiple times, deletes the overlapping original symmetric condition boundaries, converts the remaining symmetric boundary conditions into internal boundary conditions, and obtains the expandable topology flow channel.

Images