3D IC flow heat transfer testing device and method

Abstract

The invention belongs to the field of flow heat transfer testing devices and the technical field of semiconductor chip and integrated circuit packaging heat dissipation, particularly relates to a flow heat transfer testing device and method for a 3DIC, and aims to solve the problem of heat management experiment testing of a 3DIC structure under the condition of high heat flux. The device comprises alternately stacked open type heating sheet slots, micro-channel modules, MCH ceramic heating sheets, interlayer communication columns, a flow distributor and a plurality of temperature measuring elements. Through a reasonably designed fluid distribution system and a precise heat conduction structure, an equivalent substitution experiment scheme of a real 3DIC is realized, the problem of small-space temperature measurement point and heat source arrangement is solved, and the problems of non-uniform flow distribution of gas-liquid two-phase flow in a variable cross-section sub-runner and the like are solved. The device has a real-time temperature monitoring capability, is suitable for thermal management research and multiphase flow pattern observation of 3DIC, and provides a scientific basis for optimization design and performance improvement.

Description

Technical Field

[0001] The present application belongs to the field of chip heat dissipation technology, and specifically relates to a 3DIC flow heat transfer testing device. Background Art

[0002] 3DIC technology can integrate more functional units in the same footprint by stacking chips vertically, greatly improving the integration density of chips, shortening the interconnection distance between chips, and reducing signal delays, thereby improving the overall performance and speed of the circuit and reducing the power consumption of chip operation. In recent years, it has become a hot topic in many fields of research. Effective cooling can maintain the chip operating within a suitable temperature range, improve the chip's operating performance and stability, reduce thermal stress and thermal damage caused by overheating, and improve the reliability and life of the chip.

[0003] Traditional chip cooling technologies mainly include: natural convection cooling, air cooling, liquid cooling, and phase change cooling. Heat pipes, heat sinks, and thermal pastes usually assist these technologies to improve the cooling effect by increasing the cooling surface area and improving the solid heat conduction efficiency. Among them, natural convection cooling is common in low-power devices, relying on the natural flow of air to remove heat; air cooling technology increases the air flow rate and the convection heat transfer coefficient by adding fans, and is widely used in desktop hosts and other high-power devices; liquid cooling and phase change cooling technologies remove heat through the circulation of liquid coolants, with high heat dissipation efficiency, and are suitable for high-power and high-heat-density devices such as servers and high-performance computers.

[0004] However, one of the main technical challenges currently faced is that the high integration and stacking structure of 3DIC make it difficult to dissipate waste heat. The heat generated by the heating elements is concentrated in a small area, forming local hot spots, which affects the stability and life of the chip. In addition, the power consumption of different functional units in 3DIC is different, resulting in uneven heat distribution, which further increases the difficulty of thermal management. The heat of traditional chips is mainly dissipated through the surface of the chip, while the internal heat source of 3DIC needs to pass through multiple chip layers to dissipate heat, making the heat dissipation path longer and more complicated. Air cooling relies on air convection, and the heat dissipation efficiency is relatively low, which cannot meet the cooling needs of local hot spots inside 3DIC. Traditional liquid cooling or phase change cooling solutions require cooling pipes or cold plates on the chip surface or outside the package, while the internal layers of 3DIC are complex and difficult to apply directly. Traditional heat sinks usually rely on the top or bottom of the chip, and the internal layers of 3DIC cannot directly contact these heat dissipation interfaces.

[0005] At present, microchannel cooling technology makes it possible to cool the internal layers of 3DIC. By integrating microchannels inside 3DIC, the cooling fluid flows directly through each layer of the chip to take away the heat, solving the problem of internal heat accumulation. Well-designed microchannel cooling has efficient heat conduction and convection heat dissipation capabilities, and can cope with the high power consumption density and heat flux density requirements of 3DIC. However, there is no clear and feasible flow heat transfer test solution for evaluating and verifying the rationality, efficiency and reliability of microchannel design.

[0006] The current difficulties faced by 3DIC cooling technology include but are not limited to: effective experimental system design for 3DIC, heat load replacement and installation methods, micro-scale temperature measurement methods, connection methods between circulation pipelines and 3DIC test pieces, flow uniformity diversion schemes and flow pattern visualization methods for gas-liquid two-phase flows.

[0007] Taking the prior art document CN101086987A as an example, the structural design of the invention is aimed at the heat transfer problem of two-dimensional planar chips, focusing on reducing the thermal resistance and optimizing the thermal conductivity of single-layer chips, but lacks design and optimization for the vertical direction of 3DIC, does not consider the inlet flow uniformity and phase distribution optimization of the internal gas-liquid multiphase flow, lacks comprehensive testing capabilities for 3DIC flow boiling and heat transfer, and cannot adapt to the testing requirements of 3DIC non-uniform heat loads. The advantage of 3DIC over two-dimensional planar chips is that it can achieve higher integration, shorter signal transmission paths, and higher performance and energy efficiency through vertical stacking. With the rapid development of 3DIC technology, thermal management inside the chip has become a key challenge. There is an urgent need for a technical solution that can provide accurate experimental data for 3DIC, help researchers optimize the heat dissipation design of 3DIC, and ensure the long-term stability and efficient operation of 3DIC, which has important practical value and research value in the modern microelectronics industry. Summary of the invention

[0008] In order to solve at least one technical problem existing in the prior art, the present application provides a 3DIC flow heat transfer testing device, characterized in that it includes:

[0009] A left-side open-type heating plate slot and a right-side open-type heating plate slot, the top and bottom of the open-type heating plate slot have closed cavity walls, the opening is located on one side, and the other side walls are closed, the left-side open-type heating plate slot and the right-side open-type heating plate slot are alternately stacked and installed in the vertical direction; an MCH ceramic heating plate, the length, width and height of the MCH ceramic heating plate are consistent with the length, width and height of the inner cavity of the left-side open-type heating plate slot or the right-side open-type heating plate slot, and the MCH ceramic heating plate can be installed in the left-side open-type heating plate slot or the right-side open-type heating plate slot by horizontal insertion; at least one group of microchannel modules, the microchannel module is located between the upper and lower open-type heating plate slots, the microchannel module is tightly fitted with the open-type heating plate slot, and is divided into two left and right spaced apart, and each microchannel module is composed of multiple microchannels; an interlayer communication column, the interlayer communication column is a round The column is located in the center of the two microchannel modules, with a cavity structure around it and consistent with the height of the microchannel modules. It is located vertically between the upper and lower open heating plate slots and fits tightly; a patch-type temperature measuring element is installed on the wall of the open heating plate slot to monitor temperature changes in real time; an inflow interface and an outflow interface, the inflow interface and the outflow interface are respectively located at both ends of the device and connected to the circulation pipeline; a flow distributor, the flow distributor is connected to the inflow interface and the outflow interface, the outer structure of the flow distributor is a boss or base shape with thin-wall features, and it evenly transitions from a circular cross-section to a rectangular cross-section. The flow distributor contains a number of fluid distribution guide plates and a curved special-shaped triangular guide structure located in the middle. The fluid distribution guide plates are located on both sides of the curved special-shaped triangular guide structure and are fixed in a vertical direction. They are located on the side of the flow distributor away from the inflow interface and the outflow interface.

[0010] The length of the microchannel of the microchannel module is consistent with the length of the left open heating plate slot and the right open heating plate slot, and the material of the microchannel includes but is not limited to graphene enhanced copper composite material, aluminum nitride ceramic and copper.

[0011] When flow boiling heat transfer is adopted, the inner wall of the microchannel of the microchannel module is subjected to hydrophilic surface treatment.

[0012] The MCH ceramic heating sheet can be customized according to the heating characteristics and locations of the 3DIC to achieve local point heating, sheet heating and special-shaped pattern heating.

[0013] The interlayer communication column is a solid cylindrical structure with a bottom diameter of less than 1 mm and a ratio of height to cylinder diameter of no more than 5. It is used for heat transfer between micro-bumps and bonding columns of equivalent real 3DIC in the vertical direction. Calculate the equivalent heat transfer resistance by and Calculate the stress and buckling deformation, where k represents the thermal conductivity of the interlayer communication column material, A represents the bottom area of ​​the interlayer communication column, ΔT represents the temperature difference between the two ends of the interlayer communication column, H represents the height of the interlayer communication column, σ represents the stress, F represents the applied force, and F cr represents the buckling load, E represents the elastic modulus of the material, K represents the empirical parameter of the support condition, and I represents the section inertia moment. The calculation method satisfies d represents the bottom diameter of the interlayer communication column. The size of the patch-type temperature measuring element is smaller than the thickness of the MCH ceramic heating plate, and is pasted on the solid surface of the area to be measured by a copper foil sticker.

[0014] The apertures of the inflow interface and the outflow interface are consistent with the pipe diameter of the test circulation loop, and the interface is made of a transparent material and has sufficient temperature resistance.

[0015] The opening height and length of the flow distributor are consistent with the height and total width of the microchannel module. The flow distributor is made of a transparent material and has sufficient temperature resistance.

[0016] An infrared thermal imager is installed above the top of the device to monitor the surface temperature distribution.

[0017] A high-speed camera and a fill light are installed beside the outflow interface, the flow distributor and the test circulation pipeline to record the fluid flow process.

[0018] The fluid used in the test was treated with fluorescent dye, the flow rate was measured by an electromagnetic flowmeter, and transparent material pipelines were used.

[0019] Other equipments equipped in the test device include but are not limited to preheater, condenser, valve, thermal resistance temperature sensor, constant flow pump and liquid storage tank.

[0020] The structures of the multiple microchannel modules are different. The multiple microchannels can be arranged in a single layer or in multiple layers to form a microchannel module. The cross-sectional shape and size of a single microchannel are different along the length direction, and the structural features of the multiple microchannels are different.

[0021] The patch-type temperature measuring element is composed of a PT-100 or thermocouple wire with a layer of heat-conducting copper film attached to the surface.

[0022] The arc-shaped triangular guide structure is optimized by CFD, and the arc satisfies the equation

[0023]

[0024] Before the test, the outer surface of the device and the inner side of the open heater slot are cleaned and dried, the air tightness and water tightness of the device are inspected, the MCH ceramic heater coated with thermal grease on the surface is inserted into the open heater slot to ensure a tight fit without gaps, a patch temperature measuring element is installed on the outer surface of the device, the constant flow pump and valve are adjusted to control the flow rate, the preheater and condenser are adjusted to control the temperature, the temperature is measured using a patch temperature measuring element and a thermal imager, and a high-speed camera is turned on to take photos and videos of the fluid movement. When the above steps are completed and operating normally, the power output channel is turned on to adjust the power of the MCH ceramic heater to control the heating amount, and the flow heat transfer test of 3DIC under the required heat load and working conditions is completed.

[0025] The data processing method is as follows: after the temperature data is transmitted to the computer through the data acquisition device, the Kalman filter or wavelet transform data filtering algorithm is used to remove noise, and the resistance data is converted into temperature data through MATLAB software, and the time domain and frequency domain analysis methods are combined to identify the heat transfer characteristics and transient response in the system; ANSYS Fluent and OpenFOAM are used to simulate the three-dimensional temperature field, and the regional temperature gradient is verified in combination with experimental data. The temperature distribution data captured by the infrared thermal imager is combined with the image processing algorithm to optimize the temperature field information, and the three-dimensional temperature distribution map is generated through the MATLAB image processing toolbox; the fluid flow state is analyzed by high-speed camera and fluorescent staining combined with optical flow method or PIV technology, and the flow type is automatically classified using convolutional neural network, and the flow type conversion law is analyzed in time series through ARIMA or LSTM model.

[0026] The present invention has the following beneficial technical effects:

[0027] 1) In the 3DIC flow test device of the present application, due to the provision of a single-sided open heater slot and an alternating arrangement installation method, the structural strength is ensured, and the proportion of the MCH ceramic heater can be maximized, providing a larger area and space for local customized design of heat sources, which can be more in line with the actual operating conditions of 3DIC, and solves the difficulties of directly using 3DIC heat load, high price, difficult customization of temperature measurement layout, and long processing cycle. From the perspective of structural support and mechanical stability, the provision of slots can provide structural support for each heater, ensuring that their positions remain fixed during the experiment without offset virtual connection. In addition, the MCH ceramic heater itself has a brittle structure, and adding a slot design is conducive to protecting the heater and long-term use. At the same time, the use of a slot design can be closer to the packaging form in the actual 3DIC structure. The purpose of the test is not only to improve the heating performance, but more importantly to ensure the equivalence and reliability of the experiment. Real 3DICs usually have a protective coating structure on the chip. The chip heat-generating area is mainly composed of transistors and other structures. The outermost layer does not actually generate heat. This application is aware of this feature and creatively adopts a slot-shaped design to maximize the simulation of heat transfer behavior in this packaging environment. In addition, the slot can help simulate the structure of the thermal management system in actual applications. During processing, the heater slot can be integrally formed with the microchannel module and the interlayer communication column through 3D printing technology without leaving any gaps. The MCH ceramic heater required for the test only needs to be purchased separately according to the designed slot size and heating performance at a later stage. When replaced, it does not affect the overall structure of the device, and the ceramic heater can be quickly replaced.

[0028] 2) In the 3DIC flow testing device of the present application, the microchannel module can be customized according to design requirements. When conducting flow heat transfer performance tests, the heat dissipation performance and temperature uniformity performance under different design schemes and working conditions can be evaluated. Each microchannel in the microchannel module can have different structural characteristics, providing testers with sufficient selection and design space, with compact size and efficient heat transfer performance; in addition, since the inner wall of the microchannel of the microchannel module is treated with a hydrophilic surface, there is a continuous liquid film on the wall of the microchannel with good wettability. Under heating with local ultra-high heat flux density, the present application can significantly reduce local overheating and optimize the stability of flow boiling.

[0029] 3) In the 3DIC flow testing device of the present application, the MCH ceramic heating plate used has high thermal conductivity, can quickly adjust temperature changes according to the input power, has extremely high power density, can provide large power output in a small volume, can maintain stable performance at high temperatures, will not degrade due to long-term operation, has good corrosion resistance, is suitable for a wide variety of fluid working fluids, is heated evenly in the heating area and has high thermal efficiency, which solves the needs of rapid temperature change and long life in application scenarios with limited space and high-level flow heat transfer tests, and at the same time helps to reduce energy consumption and is beneficial to energy conservation and environmental protection.

[0030] 4) In the 3DIC flow testing device of the present application, since an interlayer communication column is provided, it can effectively replace the structure used to realize vertical communication, power supply and other functions in the real 3DIC. The interlayer communication column is a solid cylinder, which can realize heat conduction between different solids stacked in the vertical direction and convective heat transfer with the fluid. The interlayer communication column in the 3DIC flow testing device of the present application is surrounded by a cavity structure, which is the same as the real 3DIC, providing a test scheme design that is closer to the actual 3DIC structure and heat transfer characteristics.

[0031] 5) In the 3DIC flow testing device of the present application, a custom-designed patch-type temperature measuring element is arranged. The signal transmission line of the patch-type temperature measuring element uses silver-plated copper wire inside, and the outer insulation material uses polytetrafluoroethylene material. The wire diameter is 0.51mm, and it has high precision, high conductivity, corrosion resistance and sufficient mechanical strength. The equivalent diameter of the temperature sensor of the patch-type temperature measuring element does not exceed 4mm. The custom-designed patch-type temperature measuring element can be accurately and conveniently arranged on the wall to be measured in the 3DIC flow testing device of the present application, solving the problem of difficulty in measuring wall temperature in confined space.

[0032] 6) In the 3DIC flow test device of the present application, since the inflow interface and the outflow interface meet the customized national standard requirements, the user can connect to the circulation pipeline by threaded connection or flange connection, which solves the problem of difficult connection and sealing of complex test piece pipelines.

[0033] 7) In the 3DIC flow testing device of the present application, due to the design of the flow distributor, the fluid in each microchannel can be evenly distributed when the fluid enters the microchannel module, reducing the impact of the flow path structure on the flow heat transfer test, avoiding overheating or insufficient cooling in local areas, thereby improving the overall heat exchange efficiency of the heat exchanger; in the outlet area of ​​the microchannel module, the flow distributor is provided with an arc-shaped triangular structure and a fluid distribution guide plate, which can alleviate the flow instability caused by factors such as bubble accumulation and liquid phase blockage. In addition, the flow path of the gas-liquid two-phase flow is optimized, the flow resistance in the pipeline is reduced, and the pressure loss is reduced.

[0034] 8) In the 3DIC flow test device of the present application, an experimental design of an infrared thermal imager is provided, which can monitor the surface temperature distribution of the object to be tested and evaluate the heating uniformity in real time. Since the inlet interface, the outlet interface, the circulation pipeline, the flow distributor, etc. are all made of transparent materials with sufficient temperature resistance, and the fluid working medium used in the test is fluorescently dyed, the laminar flow, transitional flow or turbulent flow state of the fluid can be captured under the design of a high-speed camera and a fill light, and the flow type characteristics of the gas-liquid two-phase flow can also be observed; in addition, the present application also provides experimental test design schemes such as using an electromagnetic flowmeter to measure the fluid flow rate, a preheater for heating the fluid, a condenser for cooling the circulating working medium, a valve for controlling the opening and closing of the connecting pipeline of the 3DIC flow test device, a thermal resistor temperature sensor and a thermocouple for measuring the fluid temperature, a constant flow pump for providing circulation power, and a liquid storage tank for storing the working medium and preventing gas from entering the constant flow pump, which can assist in realizing the specific functions of the 3DIC flow test device of the present application, provide a practical experimental system solution, and solve the technical problems of 3DIC flow heat transfer testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the structure of the 3DIC flow heat transfer test device of the present application;

[0036] Figure 2 It is a schematic diagram of the structure of the 3DIC thermal management test module of the present application without interlayer communication columns and MCH ceramic heating plates;

[0037] Figure 3 It is a right view of the 3DIC thermal management test module of the present application without the MCH ceramic heater plate;

[0038] Figure 4 It is a left view of the 3DIC thermal management test module of the present application without the MCH ceramic heater plate;

[0039] Figure 5 It is a schematic diagram of a single-layer structure of the present application containing only one set of microchannels, heating plate slots and inter-layer communication columns;

[0040] Figures 6-1 to 6-4 These are four microchannel embodiments that may be used in this application;

[0041] Figure 7-1 It is a front view of the 3DIC flow heat transfer test device of the present application;

[0042] Figure 7-2 yes Figure 7-1 AA section view;

[0043] Figure 8-1 is a top view of the 3DIC flow heat transfer test device of the present application;

[0044] Figure 8-2 yes Figure 8-1 BB cross-sectional view;

[0045] Figure 9-1 is a bottom view of the 3DIC flow heat transfer test device of the present application;

[0046] Figure 9-2 yes Figure 9-1 CC section view;

[0047] Figure 10-1 It is a right view of the 3DIC flow heat transfer test device of the present application;

[0048] Figure 10-2 yes Figure 10-1 DD cross-sectional view;

[0049] Fig.11 It is a wireframe diagram of the flow distributor, inflow interface / outflow interface and arc-shaped triangular flow guide structure in the 3DIC flow heat transfer test device of the present application;

[0050] Fig.12 It is a rear view of the flow distributor and the inflow interface / outflow interface in the 3DIC flow heat transfer test device of the present application;

[0051] Figure 13-1 It is the main view of the 3DIC thermal management test module of this application;

[0052] Figure 13-2 This is the EE cross-sectional view of the 3DIC flow heat transfer test device without the MCH ceramic heater;

[0053] Figure 14-1 It is a top view of the flow distributor, inflow interface / outflow interface and arc-surface special-shaped triangular flow guide structure in the 3DIC flow heat transfer test device of the present application;

[0054] Figure 14-2 yes Figure 14-1 FF cross-sectional view;

[0055] Figure 14-3 yes Figure 14-1 HH cross-sectional view;

[0056] Figure 14-4 yes Figure 14-1 JJ sectional view;

[0057] Figure 15-1 It is a left view of the flow distributor and the inflow interface / outflow interface in the 3DIC flow heat transfer test device of the present application;

[0058] Figure 15-2 yes Figure 15-1 LL cross-sectional view;

[0059] Figure 15-3 yes Figure 15-1 MM cross-sectional view;

[0060] Figure 15-4 yes Figure 15-1 NN cross-sectional view;

[0061] Figure 15-5 yes Figure 15-1 OO section view;

[0062] Figure 15-6 yes Figure 15-1 PP cross-sectional view;

[0063] Figure 15-7 yes Figure 15-1 QQ section view;

[0064] Fig.16 It is a schematic diagram of the structure of a real 3DIC;

[0065] Among them: 1-left side open heater slot;

[0066] 2- Microchannel module;

[0067] 3-Open heater slot on the right side;

[0068] 4-MCH ceramic heating plate;

[0069] 5-SMD temperature measuring element;

[0070] 6- Inflow interface / outflow interface;

[0071] 7-Flow distributor;

[0072] 8-inter-layer communication column;

[0073] 9- fluid distribution guide plate;

[0074] 10- Arc surface special-shaped triangular guide structure. DETAILED DESCRIPTION

[0075] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the embodiment of this application will be described in more detail below in combination with specific examples and the drawings in the embodiments. The described embodiments are part of the embodiments of this application, rather than all the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be construed as limiting this application.

[0076] The present invention relates to a device for flow heat transfer testing of 3D integrated circuits (3DICs), and the design of the application is intended to effectively evaluate the heat transfer characteristics in the 3DIC structure, especially the performance under high heat flux density conditions. To achieve this purpose, the present invention provides an innovative testing device, the structure of which includes a left-side open-type heating plate slot 1, a right-side open-type heating plate slot 3, a microchannel module 2, an MCH ceramic heating plate 4, an interlayer communication column 8, a patch-type temperature measuring element 5, an inflow interface and an outflow interface 6, a flow distributor 7, and related auxiliary equipment.

[0077] like Figure 1 to Figure 4 As shown, the left and right open-type heating plate slots are used to accommodate the MCH ceramic heating plate 4. These slots are arranged vertically in an alternating stacking manner, so that the thermal management module of the device can ensure the structural strength of the main body of the 3DIC flow heat transfer test device at different levels and achieve the expected heating effect. In order to ensure the durability and stability of the device, the material of the slot is selected from the carbon fiber reinforced nylon material PAHT-CF with sufficient toughness, strength, rigidity and heat resistance. In terms of structural design, in order to expand the insertion area of ​​the MCH ceramic heating plate, the side wall thickness of the slot is reduced as much as possible while meeting the structural strength. In addition, the left and right open-type heating plate slots are not limited to a single layer with only one slot. Multiple slots can be opened in a single layer for installing multiple MCH ceramic heating plates of the same or different specifications and sizes, so as to realize a variety of distribution modes such as point distribution, uniform distribution, cross distribution of heat sources, and arbitrary adjustment of heat source power, fluctuation frequency and other functions.

[0078] like Figure 2 As shown in FIG6 , the microchannel module 2 is located between the upper and lower heating plate slots, tightly fitting, and is a key part for achieving efficient heat transfer and evaluating the flow heat transfer performance of 3DIC. The module is composed of multiple microchannels, which can have different structural features, such as length, width, shape, etc., and the microchannel structure in a module can be the same or different. When the purpose is to improve the heat transfer efficiency and detect the efficient flow heat transfer performance of 3DIC, the material of the microchannel is selected from materials with high thermal conductivity, low thermal expansion coefficient and sufficient mechanical properties, such as graphene-enhanced copper composite materials, aluminum nitride ceramics and copper. In addition, when flow boiling heat transfer is adopted, the inner wall of the microchannel needs to be hydrophilic surface treated to enhance the formation of the liquid film and improve the stability of boiling heat transfer. When the purpose is to observe the gas-liquid two-phase flow pattern, the microchannel module can be made of transparent PC, transparent PETG, etc. as materials, manufactured by 3D printing technology, or made of materials such as quartz glass through a specific process.

[0079] MCH ceramic heating sheet 4 is a new type of efficient, environmentally friendly and energy-saving heating element with a cubic structure, and its size matches the size of the slot. According to the specific heating characteristics and position requirements of 3DIC, corresponding to the left and right open heating sheet slots, MCH ceramic heating sheet 4 can be customized on demand to achieve a variety of heating forms such as local point heating, sheet heating, and special-shaped pattern heating. It has the characteristics of high flexibility and micro volume, and can achieve equivalent replacement of heat source heating in real chip work.

[0080] The interlayer communication column 8 is located in the center of the microchannel module 2 and is used to achieve heat conduction between solids and convection heat transfer between fluids in the vertical direction. Its design requires precise control of its structural parameters. The bottom circle diameter of the column should be less than 1 mm, and the ratio of height to bottom circle diameter should not exceed 5. Ensure that its shape and depth meet the design requirements and ensure the heat conduction effect between vertical layers. The chip layers of the real 3DIC to be simulated in this application are connected to the bonding column through micro bumps, such as Fig.16 As shown. The diameter of microbumps and bonding pillars is usually between 10 microns and 30 microns, and its value depends on the packaging technology and design requirements. The distance between microbumps and bonding pillars is usually between 40 microns and 100 microns, with extremely high integration density. In real 3DIC, the interlayers are usually cavities or epoxy resin filled except for microbumps and bonding pillars. Whether it is filled depends on the packaging technology and heat load design. Usually, epoxy resin has poor temperature resistance and may melt and fail in 3DIC with high heat flux density.

[0081] In the flow heat transfer experimental test device proposed in this application, the cavity structure is formed around the interlayer communication column. The design of the interlayer communication column can achieve the equivalent replacement of the heat transfer in the vertical direction of the real 3DIC micro-bump and the bonding column, which greatly reduces the processing difficulty and cost. The specific implementation plan takes into account both heat transfer and structural strength, as described below:

[0082] In terms of heat transfer, heat transfer in the vertical direction can be described by Fourier's law of heat conduction:

[0083]

[0084] Where Q represents the heat conducted vertically through the interlayer communication column 8 (W), k represents the thermal conductivity of the material of the interlayer communication column 8 [W / (m·K)], and A represents the bottom area of ​​the interlayer communication column 8 (m 2 ), ΔT represents the temperature difference between the two ends of the interlayer communication column 8 (K), and H represents the height of the interlayer communication column 8 (m).

[0085] Select materials with the same or close thermal conductivity as the micro-bump and bonding column materials (such as copper, aluminum, and other materials commonly used for micro-bumps and bonding columns) for equivalent design.

[0086] The size of the interlayer communication pillar 8 of the embodiment of the present application is larger than the size of the interlayer micro-bumps and bonding pillars of the real 3DIC chip to be simulated, and the heat transfer area is increased. The thermal resistance of the heat transfer path is controlled by adjusting the height H and the bottom diameter d of the interlayer communication pillar 8 to make it equivalent to the micro-bumps and bonding pillars of the real 3DIC, wherein the thermal resistance calculation method is as follows:

[0087]

[0088] For the equivalent micro-bump and bonding column design, the aspect ratio of the column is adjusted so that the thermal conduction resistance of the interlayer communication column 8 in the vertical direction is the same as that of the micro-bump and bonding column of the real 3DIC.

[0089] Since the interlayer communication column 8 not only needs to conduct heat but also needs to withstand certain mechanical loads, strength design is also key. Stress and strength analysis of the interlayer communication column 8 is used to ensure the stability of the structure.

[0090] When the inter-layer communication column 8 is subjected to pressure in the vertical direction, compression failure may occur. Use the following formula to calculate the maximum load-bearing capacity:

[0091]

[0092] Where σ is the stress (Pa) and F is the applied force (N).

[0093] Ensure that the stress σ does not exceed the yield strength σ of the material yield In this embodiment, copper, which is the same material as that of real micro-bumps and bonding pillars, may also be used as a material with similar mechanical strength.

[0094] The ratio of height to base diameter is derived from the calculation of buckling assessment, using the Euler buckling formula to avoid structural instability:

[0095]

[0096] where F cr represents the buckling load, E represents the elastic modulus of the material, K represents the empirical parameter of the support condition, and I represents the section moment of inertia, which is calculated as follows:

[0097]

[0098] Wherein d represents the bottom circle diameter. In this embodiment, the ratio of the height to the bottom circle diameter is taken as 5 as a safe value.

[0099] In order to monitor the temperature changes inside the device in real time, the present invention adopts a patch-type temperature measuring element 5. The element is composed of a PT-100 or thermocouple wire with a layer of thermal conductive copper film attached to the surface, and is installed on the wall of the heating plate slot. In order to ensure that the function of the heating plate is not affected, the size of the patch-type temperature measuring element is designed to be smaller than the thickness of the MCH ceramic heating plate, and is attached to the solid surface of the area to be measured by a copper foil sticker. In this embodiment, the area to be measured is distributed in Figure 1 , the position of the patch type temperature measuring element 5 in Figure 8, Figure 9 and Figure 10. In order to ensure the accuracy of the temperature measurement result, the accuracy of the patch type temperature measuring element 5 should not be lower than 1 / 3B level.

[0100] The several left-side open heating plate slots and right-side open heating plate slots, microchannel module, MCH ceramic heating plate and interlayer communication column together constitute a 3DIC thermal management test module, and the 3DIC thermal management test module is located in the center of a 3DIC flow heat transfer test device of the present application.

[0101] like Figure 1 , Figure 11 to Figure 1 As shown in FIG. 5 , the inflow interface and the outflow interface 6 are located at both ends of the device module and are connected to the flow distributor 7 respectively. The aperture size of the interface meets the national standard requirements, has a suitable structural strength, and is consistent with the pipe diameter of the test circulation loop, reducing the local resistance loss and uneven distribution of gas-liquid two-phase flow caused by sudden changes in the flow section. In addition, the interface and the connected pipes are made of transparent materials and have sufficient temperature resistance to observe the flow of the fluid during the test.

[0102] The design of the flow distributor 7 is the key to ensure that the gas-liquid two-phase fluid is evenly distributed to the microchannel module. The shape of the flow distributor 7 shown is a boss or base shape with thin-wall features, and the interior contains a number of fluid distribution guide plates 9 and an arc-shaped triangular guide structure 10 located in the middle. The straight side length of the structure is not less than the distance between the microchannel modules on both sides, ensuring that the fluid working medium will not flow into the interlayer communication column area, ensuring that the fluid entering the inflow interface is effectively distributed to the microchannel modules on both sides, and at the same time, the fluid flowing out of the microchannel modules on both sides flows smoothly into the outflow interface, which can greatly reduce local pressure drop losses and secondary reflux disturbances. In this embodiment, the arc of the arc-shaped triangular guide structure 10 is optimized according to CFD calculations and is fitted by the following function:

[0103]

[0104] The parameter α controls the depth of the arc, β controls the length of the curve, x represents the horizontal position along the fluid channel or the coordinate in the direction of fluid flow, y represents the height of the arc at the x position or the coordinate in the vertical direction, and the unit is the same as x, γ represents the weight of the logarithmic function, which is used to control the rate of change of the curve, and ε is a very small positive number used to avoid the singularity of the logarithmic function. In the current embodiment, y represents the arc height of the arc-shaped triangular guide structure 10, which determines the change in the size of the channel cross-section, thereby affecting the distribution and flow characteristics of the fluid.

[0105] In the above design, is a form of parabola. It is a logarithmic function, which ensures a smooth transition between the two ends of the arc of the arc-shaped triangular guide structure 10 and the adjacent structures, and the middle part has a suitable concave curvature, which is conducive to the efficient diversion of the gas-liquid two-phase flow when passing through the structure, ensuring a smooth transition and greatly weakening the flow separation phenomenon.

[0106] In this embodiment, the value of α is -25.75, the unit of β is millimeter and the value is 22.08, the value of γ is 1.12, and the value of ε is 0.001.

[0107] The working principle of this device is based on the combination of heat conduction and fluid flow heat transfer, which can achieve equivalent replacement of real 3DIC flow heat transfer. The structural diagram of real 3DIC is shown in Fig.16 As shown. First, the MCH ceramic heating plate provides local or overall heating through the open heating plate slots on the left and right sides. During the heating process, heat is transferred in the vertical direction through the interlayer communication columns, and the fluid in the microchannel module begins to flow. The fluid exchanges heat with the wall of the microchannel during the flow process. Due to the high thermal conductivity and surface treatment of the microchannel, the fluid can efficiently absorb or release heat. The fluid enters the device at the inlet interface and is evenly distributed to each microchannel through the flow distributor. After flowing through the microchannel, it is discharged through the outlet interface. With the help of related auxiliary equipment such as condensers, preheaters and working fluid pumps, a complete cycle is formed. Since the auxiliary equipment for flow heat transfer experiments is familiar to people in this field, its functions and effects are not described here.

[0108] In order to monitor the temperature change during the heat transfer process, multiple temperature measuring elements inside and on the surface of the device will record temperature data in real time, and these data can be transmitted to external monitoring equipment through the interface for analysis. At the same time, an infrared thermal imager is installed on the top of the device to further monitor the temperature distribution of 3DIC to obtain more intuitive temperature field information. After the temperature data collected by the temperature measuring element is transmitted to the computer through the data acquisition device, the data filtering algorithm (such as Kalman filtering or wavelet transform) is first used to remove noise to ensure the accuracy of the data. Subsequently, MATLAB software is used to complete the conversion of resistance data to temperature data, and the temperature change trend over time is analyzed using time domain and frequency domain analysis methods to identify the heat transfer characteristics and transient response in the system. The temperature field of the three-dimensional model of this embodiment is simulated using ANSYS Fluent software and OpenFOAM open source program package, and verified in combination with experimental data to analyze the temperature gradient in different regions. The temperature distribution data captured by the infrared thermal imager is optimized by image processing algorithms (such as histogram equalization and edge detection) to ensure the clarity of the temperature field information. At the same time, the two-dimensional thermal imaging data is converted into a three-dimensional temperature distribution map by thermal imaging analysis software (MATLAB's image processing toolbox) to further analyze the local heat conduction in each region.

[0109] In addition, the high-speed camera and fill light installed near the outflow interface can capture the details of the fluid flow during the test, and combined with the fluorescent dyeing treatment of the fluid, the flow state and flow pattern of the gas-liquid two-phase flow are more clearly visible. Among them, the flow state includes laminar flow, transitional flow and turbulent flow, and the flow pattern includes bubbly flow, annular flow, elastic flow, plunger flow, stratified flow, etc. The gas-liquid two-phase flow state recorded by the high-speed camera is processed by video data, and the flow field is analyzed by optical flow method or particle image velocimetry PIV technology to obtain the velocity vector field. At the same time, machine learning algorithms (such as convolutional neural networks CNN) are used to identify flow patterns, automatically classify different flow patterns of gas-liquid two-phase flow, and visualize the flow path and flow pattern in combination with the fluorescent dyeing effect of the fluid. The time series data of flow pattern changes are further used to study the regularity of flow pattern conversion through time series analysis models (such as ARIMA or LSTM).

[0110] Specific experimental test steps and numerical simulations are added below to further illustrate this application:

[0111] Taking the 3DIC-7nm-NC model as an example, the chip size is 50mm×50mm, and 5 chips are stacked at equal intervals in the vertical direction. The HFE7100 electronic fluorine liquid flow boiling cooling method is used for heat dissipation. The boiling point of HFE7100 electronic fluorine liquid is 61℃ and the density is 1520kg / m 3, the specific heat capacity at constant pressure is 1183 J / (kg·℃), the microchannel width is 0.4 mm, the height is 0.6 mm, the length is 54 mm, the microchannel material is copper, the coolant flow rate is 50 ml / min, the ambient temperature is 25℃, and the coolant inlet temperature is 30℃.

[0112] The experimental data of a single chip under three different power consumption conditions of 2W, 4W, and 6W are tested. The test steps are as follows:

[0113] 1. Clean and dry the device, complete the air tightness and water tightness test, and insert the MCH ceramic heating plate with appropriate thickness of thermal conductive silicone grease coated on the surface into the open heating plate slot to ensure a tight fit without gaps;

[0114] 2. Install the SMD temperature measuring element, adjust the constant flow pump and valve to control the flow rate, adjust the preheater and condenser to control the temperature, use the SMD temperature measuring element and thermal imager to measure the temperature, and turn on the high-speed camera to take photos and videos of the fluid movement;

[0115] 3. Record the temperature of the chip and coolant when the HFE-7100 working fluid is not boiling;

[0116] 4. Start the DC controllable direct current power supply equivalent chip cooling condition, adjust the power consumption of each layer of chips to be consistent, and reach 2W, 4W, and 6W in turn. Record the changes in chip surface temperature and coolant outlet temperature under different power consumptions, and focus on observing the phase change behavior of the working fluid in the microchannel;

[0117] 5. Data acquisition: monitor the temperature distribution of 3DIC in real time through the patch temperature measuring element 5 and the infrared thermal imager, use a high-speed camera to record the boiling of the working fluid and the gas-liquid two-phase flow state, use a pressure gauge and a differential pressure gauge to record the pressure and differential pressure data, and use a flow meter to read the flow data;

[0118] 6. Data conversion processing, flow pattern visualization and acquisition device temperature distribution.

[0119] Furthermore, the gas-liquid two-phase flow pattern and temperature distribution of HFE7100 under the current working conditions were simulated using the OpenFOAM open source package. The liquid thermal conductivity of HFE7100 was set to 0.07W / (m·K), the microchannel thermal conductivity was 385W / (m·K), the liquid flow rate was 0.5m / s, the phase change latent heat was 112kJ / kg, and the surface tension was 13.6mN / m. The calculation results showed that under the condition of low power consumption of 2W, HFE-7100 did not reach the phase change boiling temperature, the outlet coolant temperature was 36℃, and the cooling effect mainly depended on single-phase liquid cooling. When the power consumption increased to 4W, the chip surface temperature reached 63℃, and phase change began to occur in some areas of the microchannel. The cooling effect was significantly enhanced, and bubbly flow appeared. Under the condition of high power consumption of 6W, HFE-7100 boiled in large quantities in the microchannel, forming a stable two-phase flow, the chip surface temperature was controlled within 78℃, and the cooling efficiency was significantly improved. The gas-liquid two-phase flow patterns are mainly annular flow and slug flow, which conforms to the boiling cooling characteristics under high heat flux.

[0120] This device constructs a heat transfer physical model equivalent to the real 3DIC, simulates the real working environment of 3DIC, designs a practical flow heat transfer experimental test scheme, can provide accurate heat transfer data, and provides a scientific basis for optimizing design and performance improvement. For example, this device can be used to evaluate the cooling effect of different cooling liquids, different refrigerant flow rates, different microchannel structure types, different heat source powers, different heat source sizes and shapes, etc., to help design efficient cooling systems and optimize the numerical model of microscale multi-physics flow boiling. This embodiment provides a well-designed 3DIC flow heat transfer test device, through which a solid foundation is provided for research and development in related fields.

[0121] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A 3DIC flow heat transfer test device, characterized in that: include: A left-side open-type heating plate slot and a right-side open-type heating plate slot, the top and bottom of the open-type heating plate slot have closed cavity walls, the opening is located on one side, and the other side walls are closed, the left-side open-type heating plate slot and the right-side open-type heating plate slot are alternately stacked and installed in the vertical direction; an MCH ceramic heating plate, the length, width and height of the MCH ceramic heating plate are consistent with the length, width and height of the inner cavity of the left-side open-type heating plate slot or the right-side open-type heating plate slot, and the MCH ceramic heating plate is installed in the left-side open-type heating plate slot or the right-side open-type heating plate slot by horizontal insertion; at least one group of microchannel modules, the microchannel modules are located The microchannel module is tightly fitted with the open heating plate slot between the upper and lower open heating plate slots, and is divided into two left and right spaced parts, each of which is composed of multiple microchannels; an interlayer communication column, which is a cylinder located in the center of the two microchannel modules, with a cavity structure around it, and is consistent with the height of the microchannel module, and is located between the upper and lower open heating plate slots in the vertical direction and tightly fitted; a patch-type temperature measuring element, which is installed on the wall surface of the open heating plate slot for real-time monitoring of temperature changes; an inflow interface and an outflow interface, which are respectively located at both ends of the device and connected to the circulation pipeline; A flow distributor, the flow distributor is connected to the inflow interface and the outflow interface, the external structure of the flow distributor is a boss or base shape with thin-wall features, and the circular cross-section evenly transitions to a rectangular cross-section. The flow distributor contains a plurality of fluid distribution guide plates and an arc-shaped triangular guide structure located in the middle. The fluid distribution guide plates are located on both sides of the arc-shaped triangular guide structure and are fixed in a vertical direction, and are located on the side of the flow distributor away from the inflow interface and the outflow interface.

2. The device according to claim 1, characterized in that: The length of the microchannel of the microchannel module is consistent with the length of the left open heating plate slot and the right open heating plate slot, and the material of the microchannel includes but is not limited to graphene enhanced copper composite material, aluminum nitride ceramic and copper.

3. The device according to claim 1, characterized in that: When flow boiling heat transfer is adopted, the inner wall of the microchannel of the microchannel module is subjected to hydrophilic surface treatment.

4. The device according to claim 1, characterized in that: The MCH ceramic heating sheet is customized according to the heating characteristics and locations of the 3DIC to achieve local point heating, sheet heating or special-shaped pattern heating.

5. The device according to claim 1, characterized in that: The interlayer communication column is a solid cylindrical structure with a bottom diameter of less than 1 mm and a ratio of height to cylinder diameter of no more than 5. It is used for heat transfer between micro-bumps and bonding columns of equivalent real 3DIC in the vertical direction. Calculate the equivalent heat transfer resistance by and Calculate the stress and buckling deformation, where k represents the thermal conductivity of the interlayer communication column material, A represents the bottom area of ​​the interlayer communication column, ΔT represents the temperature difference between the two ends of the interlayer communication column, H represents the height of the interlayer communication column, σ represents the stress, F represents the applied force, and F cr represents the buckling load, E represents the elastic modulus of the material, K represents the empirical parameter of the support condition, and I represents the moment of inertia of the section. The calculation method satisfies d represents the bottom circle diameter of the inter-layer communication column.

6. The device according to claim 1, characterized in that: The size of the patch-type temperature measuring element is smaller than the thickness of the MCH ceramic heating sheet, and is pasted on the solid surface of the area to be measured by a copper foil sticker.

7. The device according to claim 1, characterized in that: The apertures of the inflow interface and the outflow interface are consistent with the pipe diameter of the test circulation loop, and the interface is made of a transparent material and has sufficient temperature resistance.

8. The device according to claim 1, characterized in that: The opening height and length of the flow distributor are consistent with the height and total width of the microchannel module. The flow distributor is made of a transparent material and has sufficient temperature resistance.

9. The device according to claim 1, characterized in that: An infrared thermal imager is installed above the top of the device to monitor the surface temperature distribution.

10. The device according to claim 1, characterized in that: A high-speed camera and a fill light are installed beside the outflow interface, the flow distributor and the test circulation pipeline to record the fluid flow process.

11. The device according to claim 10, characterized in that: The fluid used in the test was treated with fluorescent dye, the flow rate was measured by an electromagnetic flowmeter, and transparent material pipelines were used.

12. The device according to claim 1, characterized in that: Other equipments equipped in the test device include but are not limited to preheater, condenser, valve, thermal resistance temperature sensor, constant flow pump and liquid storage tank.

13. The device according to claim 1, characterized in that: The structures of the multiple microchannel modules are different. The multiple microchannels are arranged in a single layer or in multiple layers to form a microchannel module. The cross-sectional shape and size of a single microchannel are different along the length direction. The structural features of the multiple microchannels are different.

14. The device according to claim 1, characterized in that: The patch-type temperature measuring element is composed of a PT-100 or thermocouple wire with a layer of heat-conducting copper film attached to the surface.

15. The device according to claim 1, characterized in that: The arc-shaped triangular guide structure is optimized by CFD, and the arc satisfies the equation 16. A method for testing a 3DIC flow heat transfer testing device, using the device according to any one of claims 1 to 15 for measurement, characterized in that: Before the test, the outer surface of the device and the inner side of the open heater slot are cleaned and dried, the air tightness and water tightness of the device are inspected, the MCH ceramic heater coated with thermal grease on the surface is inserted into the open heater slot to ensure a tight fit without gaps, a patch temperature measuring element is installed on the outer surface of the device, the constant flow pump and valve are adjusted to control the flow rate, the preheater and condenser are adjusted to control the temperature, the temperature is measured using a patch temperature measuring element and a thermal imager, and a high-speed camera is turned on to take photos and videos of the fluid movement. When the above steps are completed and operating normally, the power output channel is turned on to adjust the power of the MCH ceramic heater to control the heating amount, and the flow heat transfer test of 3DIC under the required heat load and working conditions is completed.

17. The method according to claim 16, wherein the data processing method is as follows: after the temperature data is transmitted to the computer through the data acquisition device, the Kalman filter or wavelet transform data filtering algorithm is used to remove noise, and the resistance data is converted into temperature data through MATLAB software, and the heat transfer characteristics and transient response in the system are identified by combining time domain and frequency domain analysis methods; the three-dimensional temperature field is simulated by ANSYS Fluent and OpenFOAM, and the regional temperature gradient is verified by combining experimental data, the temperature distribution data captured by the infrared thermal imager is combined with the image processing algorithm to optimize the temperature field information, and the three-dimensional temperature distribution map is generated by the MATLAB image processing toolbox; the fluid flow state is analyzed by high-speed camera and fluorescent staining combined with optical flow method or PIV technology, the flow type is automatically classified by using convolutional neural network, and the flow type conversion law is analyzed by time series through ARIMA or LSTM model.

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