3dic flow heat transfer test apparatus and method

Abstract

The application belongs to the field of flow heat transfer test device and the field of semiconductor chip and integrated circuit packaging heat dissipation technology, and particularly relates to a flow heat transfer test device and method for 3DIC, aiming to solve the problem of experimental test of thermal management of 3DIC structure under high heat flow density condition. The device comprises open heating sheet slots, micro-channel modules, MCH ceramic heating sheets, interlayer communication columns, flow distributors and multiple temperature measuring elements which are alternately stacked. Through a rationally designed fluid distribution system and a precise heat conduction structure, an equivalent replacement experimental scheme of a real 3DIC is realized, the problems of temperature measuring point and heat source arrangement in a small space are solved, and the problems of uneven flow distribution of gas-liquid two-phase flow in a variable cross-section shunt are optimized. The device has 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 application belongs to the technical field of chip heat dissipation, and particularly relates to a 3DIC flow heat transfer testing device. BACKGROUND

[0002] 3DIC technology can integrate more functional units in the same footprint by stacking chips in the vertical direction, greatly improving the integration density of the chip, shortening the interconnection distance between chips, reducing signal delay, thereby improving the overall performance and speed of the circuit, reducing the power consumption of the chip, and has become a research hotspot in many fields in recent years. Effective cooling can maintain the chip within the appropriate temperature range, improve the working performance and stability of the chip, 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 cooling technology, liquid cooling cooling technology and phase change cooling technology. Heat pipes, heat sinks and thermal paste are usually used to assist these technologies to improve the cooling effect by increasing the heat dissipation surface area and improving the solid thermal conductivity efficiency. Among them, natural convection cooling is commonly used in low-power devices, relying on the natural flow of air to carry away heat; air cooling cooling technology is to increase the air flow rate by increasing the fan to increase the convective heat transfer coefficient, and is widely used in high-power devices such as desktop computers; liquid cooling cooling technology and phase change cooling technology use liquid coolant circulation to carry away heat, and have high cooling efficiency, suitable for high-power and high-heat-density devices such as servers and high-performance computers.

[0004] However, one of the main technical problems currently faced is that the high integration and stacked structure of 3DIC make it difficult to dissipate waste heat, and the heat generated by the heat-generating 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, leading to uneven heat distribution, further increasing 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 complex. Air cooling relies on air convection, and the cooling efficiency is relatively low, which cannot meet the cooling needs of local hot spots inside 3DIC. Traditional liquid cooling or phase change cooling schemes need to set up cooling pipes or cold plates on the surface of the chip or outside the package, while the internal levels of 3DIC are complex and difficult to apply directly. Traditional heat sinks usually rely on the top or bottom of the chip, while the internal levels of 3DIC cannot directly contact these heat dissipation interfaces.

[0005] At present, micro-channel cooling technology makes it possible to cool 3DIC internally, by integrating micro-channels inside 3DIC, making cooling fluid flow directly through each layer of chips, taking away heat, solving the problem of internal heat accumulation. A reasonable micro-channel cooling design has high heat conduction and convection cooling capacity, which can meet the high power density and heat flux density requirements of 3DIC. However, how to evaluate and verify the rationality, efficiency and reliability of the micro-channel design, there is no clear and feasible flow and heat transfer test scheme.

[0006] Now the 3DIC cooling technology is facing the same difficulty, including but not limited to: the design of an effective experimental system for 3DIC, the replacement of thermal load and its installation method, the temperature measurement method of small scale, the connection method of circulating pipeline and 3DIC test piece, the flow uniformity guide scheme and the flow pattern visualization method of gas-liquid two-phase flow, etc.

[0007] For example, the prior art document CN101086987A, the structure design of this invention focuses on the heat transfer problem of two-dimensional plane chip, pays attention to the reduction of thermal resistance and optimization of heat conduction of single layer chip, but lacks design and optimization in the vertical direction of 3DIC, does not consider the inlet flow uniformity and phase distribution optimization of internal gas-liquid multiphase flow, lacks comprehensive testing capability for 3DIC flow boiling and heat transfer, and cannot meet the testing needs of non-uniform thermal load of 3DIC. The advantage of 3DIC compared with two-dimensional plane chip is that it realizes higher integration, shorter signal transmission path and higher performance and energy efficiency through vertical stacking. With the rapid development of 3DIC technology, the heat management inside the chip becomes a key challenge, and an accurate experimental data for 3DIC is needed to help researchers optimize the heat dissipation design of 3DIC and ensure the long-term stability and high efficiency of 3DIC. This technology has important practical and research value in modern microelectronics industry. SUMMARY

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

[0009] The left and right open heating sheet slots have closed cavity walls at the top and bottom, and an opening on one side, with the other side wall closed. The left and right open heating sheet slots are alternately stacked vertically. The MCH ceramic heating sheet has the same length, width and height as the internal cavity of the left or right open heating sheet slot. The MCH ceramic heating sheet can be installed in the left or right open heating sheet slot by horizontal insertion. At least one set of micro-channel modules is located between the upper and lower open heating sheet slots. The micro-channel modules are tightly attached to the open heating sheet slots and are spaced apart into left and right two parts. Each micro-channel module is composed of multiple micro-channels. The interlayer communication column is a cylinder located in the center of the two micro-channel modules. The periphery is a hollow structure, and the height is consistent with the micro-channel module. It is located vertically between the upper and lower open heating sheet slots and is tightly attached. The patch type temperature measuring element is installed on the wall of the open heating sheet slot for real-time monitoring of temperature changes. The inflow and outflow interfaces are connected to the circulation pipeline at both ends of the device. The flow distributor is connected to the inflow and outflow interfaces. The flow distributor has a boss or base shape with a thin wall feature. The circular cross-section transitions uniformly to a rectangular cross-section. The flow distributor contains several fluid distribution guide vanes and an arc-shaped special triangular guide structure in the middle. The fluid distribution guide vanes are located on both sides of the arc-shaped special triangular guide structure and are fixed vertically. They are located on the side of the flow distributor away from the inflow and outflow interfaces.

[0010] The micro-channel length of the micro-channel module is consistent with the length of the left and right open heating sheet slots. The micro-channel material includes but is not limited to graphene reinforced copper composite, aluminum nitride ceramic and copper.

[0011] When flow boiling heat transfer is used, the micro-channel inner wall is treated with a hydrophilic surface.

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

[0013] The interlayer communication column is a solid cylinder structure with a bottom surface diameter less than 1mm and a height to diameter ratio not exceeding 5. It is used to equivalent the vertical heat transfer of real 3DIC micro-bumps and bonding columns. Calculate the equivalent heat transfer thermal resistance. And The stress and buckling deformation are calculated, wherein 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, F cr represents the buckling load, E represents the elastic modulus of the material, K represents the support condition empirical parameter, I represents the cross-sectional moment of inertia, and the calculation method satisfies d represents the diameter of the bottom circle of the interlayer communication column. 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 measured area by a copper foil sticker.

[0014] The pore diameters of the inflow interface and the outflow interface are consistent with the pipe diameter of the test circulation loop, the interfaces are made of transparent materials and have 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 transparent materials and has sufficient temperature resistance.

[0016] An infrared thermal imager is installed above the top of the device for monitoring 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 for recording the fluid flow process.

[0018] The fluid working medium used in the test is subjected to fluorescent dyeing treatment, the flow is measured by an electromagnetic flowmeter, and transparent material pipelines are used.

[0019] Other equipment provided by the test device includes but is not limited to a preheater, a condenser, a valve, a thermistor temperature sensor, a constant flow pump and a liquid storage tank.

[0020] The structures of the plurality of microchannel modules are different, the plurality of microchannels can be arranged in a single layer or 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 plurality of microchannels are different.

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

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

[0023]

[0024] Before testing, the outer surface of the device and the inner side of the open heating sheet slot are cleaned and dried, the device is tested for air tightness and water tightness, the MCH ceramic heating sheet coated with heat-conducting silicone on the surface is inserted into the open heating sheet slot to ensure close fitting without gap, the patch type temperature measuring element is installed on the outer surface of the device, the constant flow pump and the valve are adjusted to control the flow rate, the preheater and the condenser are adjusted to control the temperature, the temperature is measured by using the patch type temperature measuring element and the thermal imager, the high-speed camera is started to take photos and videos of fluid movement, when the above steps are completed and normally operated, the power output channel is started to adjust the power of the MCH ceramic heating sheet to control the heating amount, and the flow heat transfer test of the 3DIC under the required heat load and working condition is completed.

[0025] The data processing method is as follows: after the temperature data is transmitted to the computer through the data collector, the Kalman filter or wavelet transform data filtering algorithm is used to remove noise, the resistance data is converted into temperature data through the MATLAB software, the heat transfer characteristics and transient response in the system are identified by combining the time domain and frequency domain analysis methods, the three-dimensional temperature field is simulated by using ANSYS Fluent and OpenFOAM, 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 diagram is generated through the MATLAB image processing toolbox; the flow state of the fluid is analyzed by combining the light flow method or PIV technology through the high-speed camera and fluorescence dyeing processing, the flow pattern is automatically classified by using the convolutional neural network, and the time series analysis of the flow pattern conversion law is carried out by using the ARIMA or LSTM model.

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

[0027] 1) In the 3DIC flow test device of the present application, the single-sided opening type heating sheet slot and the alternate arrangement installation method are provided, which not only ensures the structural strength, but also maximizes the proportion of MCH ceramic heating sheet, provides more area and local customized design heat source space, and can be more in line with the real operating conditions of 3DIC, solving the problems of difficult control, high price, difficult temperature measurement arrangement and long processing cycle of direct use of 3DIC thermal load. From the perspective of structural support and mechanical stability, the slot can provide structural support for each heating sheet to ensure that their positions remain fixed during the experiment and do not deviate from the virtual connection. Moreover, the MCH ceramic heating sheet itself is relatively fragile, and the addition of a slot design is beneficial to the protection of the heating sheet and long-term use. At the same time, the use of 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. The real 3DIC usually has a protective coating structure on the chip, and the chip heating area is mainly the transistor structure, and the outermost layer itself does not actually heat. The present application is aware of this feature and creatively uses the slot 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. The heating sheet slot can be integrally formed without gaps with the microchannel module and the interlayer communication column through 3D printing technology, and the MCH ceramic heating sheet required for testing can be purchased separately according to the designed slot size and heating performance, which does not affect the overall structure of the device when replaced, and realizes the rapid replacement of the ceramic heating sheet.

[0028] 2) In the 3DIC flow test device of the present application, the microchannel module can be customized and processed according to design needs, and the heat dissipation performance and temperature uniformity performance under different design schemes and working conditions can be evaluated when the flow heat transfer performance test is carried out. Each microchannel in the microchannel module can have different structural characteristics, providing sufficient selection and design space for test personnel, with compact volume and high efficient heat transfer performance; in addition, since the inner wall of the microchannel of the microchannel module is subjected to hydrophilic surface treatment, the microchannel wall has a continuous liquid film, with good wettability, under local super-high heat flux heating, the present application can significantly reduce local overheating and optimize the stability of flow boiling.

[0029] 3) In the 3DIC flow testing device of this application, the MCH ceramic heating element used has high thermal conductivity, can quickly adjust the temperature change according to the input power, has extremely high power density, can provide a large power output in a small volume, can maintain stable performance at high temperature, will not degrade performance due to long-term operation, has good corrosion resistance, is suitable for a wide variety of fluid working media, and is uniformly heated in the heating area with high thermal efficiency. It solves the needs of space-constrained application scenarios and high-level flow heat transfer testing for rapid temperature change and long service life, while also helping to reduce energy consumption and promoting energy conservation and environmental protection.

[0030] 4) In the 3DIC flow testing device of this application, the interlayer communication column can effectively replace the structure in the real 3DIC used to realize vertical communication, power supply and other functions. The interlayer communication column is a solid cylinder, which can realize heat conduction between different solids stacked vertically and convective heat transfer between them and the fluid. The interlayer communication column in the 3DIC flow testing device of this application is surrounded by a cavity structure, which is the same as that of the real 3DIC, and provides 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 this application, due to the arrangement of a custom-designed patch-type temperature sensing element, the signal transmission line of the patch-type temperature sensing element uses silver-plated copper wire inside and polytetrafluoroethylene material for the outer insulation material. The wire diameter is 0.51mm, which has high precision, high conductivity, corrosion resistance and sufficient mechanical strength. The equivalent diameter of the temperature sensor of the patch-type temperature sensing element does not exceed 4mm. The custom-designed patch-type temperature sensing element can be accurately and conveniently arranged on the test wall surface of the 3DIC flow testing device of this application, solving the problem of difficulty in measuring the wall surface temperature in a confined space.

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

[0033] 7) In the 3DIC flow testing device of this 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 influence 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, due to the setting of the arc-shaped triangular structure and the fluid distribution guide plate, can alleviate the flow instability caused by factors such as bubble accumulation and liquid phase blockage. In addition, it optimizes the flow path of gas-liquid two-phase flow, reduces the flow resistance in the pipe, and reduces pressure loss.

[0034] 8) In the 3DIC flow test device of the present application, the experimental design of the infrared thermal imager is provided, which can monitor the surface temperature distribution of the object to be tested in real time and evaluate the heating uniformity. Since the inflow interface, outflow interface, circulating pipeline, flow distributor and the like are all transparent and have sufficient temperature resistance, and the fluid working medium used for testing is subjected to fluorescent dyeing treatment, the flow state of laminar flow, transition flow or turbulent flow can be shot under the design of high-speed camera and fill light, and the flow pattern characteristics of gas-liquid two-phase flow can also be observed. In addition, the present application also provides an experimental test design scheme, which adopts an electromagnetic flowmeter to measure the fluid flow, a preheater to heat the fluid, a condenser to cool the circulating working medium, a valve to control the opening and closing of the connecting pipeline of the 3DIC flow test device, a thermal resistance type temperature sensor and a thermocouple to measure the fluid temperature, a constant flow pump to provide circulating power, a liquid storage tank to store the working medium and prevent gas from entering the constant flow pump, and the like, which can assist in realizing the specific functions of the 3DIC flow test device of the present application, provide a practical experimental system scheme, and solve the technical problems of 3DIC flow heat transfer test. BRIEF DESCRIPTION OF DRAWINGS

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

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

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

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

[0039] Figure 5 is a single-layer structural schematic diagram of the present application containing only one group of microchannels, heating sheet slots and interlayer communication columns;

[0040] Figures 6-1 to 6-4 is four kinds of microchannel embodiments that can be used in the present application;

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

[0042] Figure 7-2 is an A-A sectional view of Figure 7-1 ;

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

[0044] Figure 8-2 is a B-B sectional view of Figure 8-1

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

[0046] Figure 9-2 is a C-C sectional view of Figure 9-1

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

[0048] Figure 10-2 is a D-D sectional view of Figure 10-1

[0049] Figure 11 is an isometric view of the flow distributor, inflow / outflow interface and arc-shaped special triangular flow guide structure in the 3DIC flow heat transfer test apparatus of the present application;

[0050] Figure 12 is a back view of the flow distributor and inflow / outflow interface in the 3DIC flow heat transfer test apparatus of the present application;

[0051] Figure 13-1 is a front view of the 3DIC thermal management test module of the present application;

[0052] Figure 13-2 is an E-E sectional view of the 3DIC flow heat transfer test apparatus without MCH ceramic heating sheet;

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

[0054] Figure 14-2 is a F-F sectional view of Figure 14-1

[0055] Figure 14-3 is a H-H sectional view of Figure 14-1

[0056] Figure 14-4 is a J-J sectional view of Figure 14-1

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

[0058] Figure 15-2 is a L-L sectional view of Figure 15-1 ​​​​​​​

[0059] Figure 15-3 is Figure 15-1 a M-M sectional view of the figure 1;

[0060] Figure 15-4 is Figure 15-1 a N-N sectional view of the figure 1;

[0061] Figure 15-5 is Figure 15-1 a O-O sectional view of the figure 1;

[0062] Figure 15-6 is Figure 15-1 a P-P sectional view of the figure 1;

[0063] Figure 15-7 is Figure 15-1 a Q-Q sectional view of the figure 1;

[0064] Figure 16 is a schematic diagram of the structure of the real 3DIC;

[0065] wherein: 1-left open heating sheet slot;

[0066] 2-microchannel module;

[0067] 3-right open heating sheet slot;

[0068] 4-MCH ceramic heating sheet;

[0069] 5-patch temperature measuring element;

[0070] 6-inflow interface / outflow interface;

[0071] 7-flow distributor;

[0072] 8-interlayer communication column;

[0073] 9-fluid distribution guide vane;

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

[0075] In order to make the purpose, technical scheme and advantages of the application clearer, the technical scheme of the embodiments of the application will be described in more detail below in combination with specific examples and the accompanying drawings in the embodiments. The described embodiments are part of the embodiments of the application, not all the embodiments. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the application, and cannot be understood as a limitation of the application.

[0076] The present application relates to a device for 3D integrated circuit (3DIC) flow heat transfer test, the design of the application aims to effectively evaluate the heat transfer characteristics in 3DIC structure, especially the performance under high heat flux density conditions. In order to achieve this purpose, the present application provides an innovative test device, which comprises a left open heating fin slot 1, a right open heating fin slot 3, a microchannel module 2, an MCH ceramic heating fin 4, an interlayer communication column 8, a patch temperature measuring element 5, an inflow and outflow interface 6, a flow distributor 7 and related auxiliary equipment.

[0077] As shown in Figures 1 to 4 , the left and right open heating fin slots are used to accommodate the MCH ceramic heating fin 4, which are vertically arranged in an alternating stack, so that the heat management module of the device can ensure the structural strength of the 3DIC flow heat transfer test device body 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 to be carbon fiber reinforced nylon material PAHT-CF, which has sufficient toughness, strength, stiffness and heat resistance. In terms of structural design, in order to expand the insertion area of the MCH ceramic heating fin, the thickness of the side wall of the slot is thinned as much as possible under the premise of meeting the structural strength. In addition, the left and right open heating fin slots are not limited to a single layer with only one slot, and multiple slots can be opened in a single layer for installing multiple MCH ceramic heating fins of the same or different specifications and sizes, to realize various distribution modes of heat sources such as point distribution, uniform distribution and cross distribution, and to realize the functions of arbitrary adjustment of heat source power and fluctuation frequency.

[0078] As shown in Figure 2 and Fig. 6, the microchannel module 2 is located between the upper and lower heating fin slots and is tightly fitted, which is the key part of realizing efficient heat transfer and evaluating the flow heat transfer performance of 3DIC. The module is composed of multiple microchannels, which can have different structural characteristics such as length, width and shape, and the microchannel structures within a module can be the same or different. When the purpose is to improve the heat transfer efficiency and detect the high-efficiency flow heat transfer performance of 3DIC, the material of the microchannel is selected to be a material with high thermal conductivity, low thermal expansion coefficient and sufficient mechanical properties, such as graphene reinforced copper composite material, aluminum nitride ceramic and copper. In addition, when flow boiling heat transfer is used, the inner wall of the microchannel also needs to be treated with hydrophilic surface to enhance the formation of liquid film and improve the stability of boiling heat transfer. When the purpose is to observe the flow pattern of gas-liquid two-phase flow, the microchannel module can be made of transparent PC, transparent PETG, etc. as the material, which is manufactured by 3D printing technology, or can be made of quartz glass and other materials processed by a specific process.

[0079] The MCH ceramic heating sheet 4 is a new type of high-efficiency environmentally friendly and energy-saving heating element, which adopts a cubic structure, and the size thereof is matched with the size of the slot. According to the specific heating characteristics and position requirements of the 3DIC, the MCH ceramic heating sheet 4 can be customized as required, corresponding to the left and right open-type heating sheet slots, to realize various heating forms such as local point heating, sheet heating and special-shaped pattern heating, and has the characteristics of high flexibility and micro volume, and realizes the equivalent replacement of the heat source heating in the real chip working.

[0080] The interlayer communication column 8 is located in the center of the microchannel module 2, and is used to realize the heat conduction between solids and the convection heat transfer with the fluid in the vertical direction. Its design needs to accurately control its structural parameters, the bottom circle diameter of the column should be less than 1 mm, and the ratio of the height to the bottom circle diameter should not exceed 5, so as to ensure that the shape and depth meet the design requirements and ensure the longitudinal interlayer heat conduction effect. The chip layers of the real 3DIC to be simulated in the present application are connected through micro bumps and bonding columns, as shown in Figure 16 The diameter of the micro bump and the bonding column is usually between 10 microns and 30 microns, and the value depends on the packaging technology and design requirements, and the micro bump and the bonding column spacing is usually in the range of 40 microns to 100 microns, with extremely high integration density. In addition to the micro bump and the bonding column, the interlayer of the real 3DIC is usually a cavity or filled with epoxy resin, and whether it is filled depends on the packaging technology and thermal load design, and the epoxy resin has poor temperature resistance and may melt and fail in high heat flux 3DIC.

[0081] In the flow heat transfer experimental test device proposed in the present application, the space around the interlayer communication column is a cavity structure, and the design of the interlayer communication column can achieve the equivalent replacement of the vertical heat transfer of the micro bump and the bonding column in the real 3DIC, greatly reducing the processing difficulty and cost. The specific implementation scheme also considers the heat transfer and structural strength, as follows:

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

[0083]

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

[0085] A material (such as copper, aluminum and the like commonly used for micro bumps and bonding columns) with the same or similar thermal conductivity as the material of the micro bump and the bonding column is selected for equivalent design.

[0086] The size of the interlayer communication column 8 of the embodiment of the present application is larger than the size of the real 3DIC chip interlayer micro-bump and bonding column to be simulated, the heat transfer area is increased, and the thermal resistance of the heat transfer path is controlled by adjusting the height H and the bottom surface diameter d of the interlayer communication column 8, so as to be equivalent to the micro-bump and bonding column 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 cylinder is adjusted so that the vertical conduction thermal resistance of the interlayer communication column 8 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 conducts heat but also needs to bear a certain mechanical load, the strength design is also critical, and the stress and strength analysis of the interlayer communication column 8 is used to ensure the stability of the structure.

[0090] When the interlayer communication column 8 is subjected to pressure in the vertical direction, compression failure may occur. The following formula is used to calculate the maximum bearing capacity:

[0091]

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

[0093] Ensure that the stress σ does not exceed the yield strength σ yield The embodiment selects the same material copper as the real micro-bump and bonding column, and materials with similar mechanical strength can also be used.

[0094] The ratio of height to bottom circle diameter is derived from the calculation of buckling evaluation, and the Euler buckling formula is used to avoid structural instability:

[0095]

[0096] Where F cr represents the buckling load, E represents the elastic modulus of the material, K represents the support condition empirical parameter, and I represents the cross-sectional moment of inertia, and the calculation method is as follows:

[0097]

[0098] Where d represents the bottom circle diameter, and the ratio of height to bottom circle diameter in the embodiment is taken as 5 as a safety value.

[0099] To monitor temperature changes inside the device in real time, this invention employs a patch-type temperature sensing element 5. This element consists of a PT-100 or thermocouple wire with a thin thermally conductive copper film attached to its surface, and is mounted on the wall of the heating element slot. To ensure that the function of the heating element is not affected, the size of the patch-type temperature sensing element is designed to be smaller than the thickness of the MCH ceramic heating element, and it is attached to the solid surface of the area to be measured using copper foil stickers. In this embodiment, the area to be measured is distributed in... Figure 1 The positions of the patch-type temperature sensing element 5 are marked in Figures 8, 9, and 10. To ensure the accuracy of the temperature measurement results, the accuracy of the patch-type temperature sensing element 5 should be no less than 1 / 3B grade.

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

[0101] like Figure 1 , Figures 11 to 1 As shown in Figure 5, the inlet and outlet ports 6 are located at both ends of the device module and are connected to the flow distributor 7, respectively. The port diameters meet national standards, possess appropriate structural strength, and are consistent with the pipe diameter of the test circulation loop to reduce local resistance losses and uneven gas-liquid two-phase flow distribution caused by abrupt changes in the flow cross-section. Furthermore, both the ports and the connected pipes are made of transparent material and possess sufficient temperature resistance to allow for observation of fluid flow during testing.

[0102] The design of the flow distributor 7 is crucial to ensuring the uniform distribution of the gas-liquid two-phase fluid to the microchannel modules. The flow distributor 7 shown is shaped like a boss or base with thin-walled features. Internally, it contains several fluid distribution guide vanes 9 and a centrally located arc-shaped triangular guide structure 10. The length of the straight side of this structure is not less than the distance between the two microchannel modules, ensuring that the working fluid does not flow into the interlayer communication column area. This guarantees that the fluid entering through the inlet is effectively distributed to the microchannel modules on both sides, while the fluid flowing out of the microchannel modules flows smoothly into the outlet, significantly reducing local pressure drop loss and secondary backflow disturbance. In this embodiment, the arc of the arc-shaped triangular guide structure 10 is optimized based on CFD calculations and fitted using the following function:

[0103]

[0104] where parameter a controls the depth of the arc, parameter b 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, unit is the same as x, g represents the weight of the logarithmic function, which is used to control the rate of change of the curve, and e 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 special triangular guide structure 10, which determines the change of the channel cross-sectional size, thereby affecting the distribution and flow characteristics of the fluid.

[0105] In the above design, is a form of a parabola, is a logarithmic function, which ensures that the two ends of the arc of the arc-shaped special triangular guide structure 10 are smoothly transitioned with the adjacent structures, and the middle part has a suitable concave curvature, which is beneficial to the efficient distribution of gas-liquid two-phase flow fluid when passing through the structure, ensures smooth transition, and greatly weakens the phenomenon of flow separation.

[0106] In the current embodiment, the value of a is -25.75, the unit of b is millimeter and the value is 22.08, the value of g is 1.12, and the value of e is 0.001.

[0107] The working principle of the device is based on the combination of heat conduction and fluid flow heat transfer, which realizes the equivalent replacement of real 3DIC flow heat transfer. The structure diagram of the real 3DIC is shown in Figure 16 Firstly, the MCH ceramic heating sheet provides local or overall heating through the left and right opening type heating sheet slot. During the heating process, heat is transmitted in the vertical direction through the interlayer communication column, and at the same time, the fluid in the microchannel module starts to flow. The fluid exchanges heat with the microchannel wall 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 through the inflow interface, is uniformly distributed into each microchannel through the flow distributor, flows through the microchannel, and then is discharged through the outflow interface. With the help of related auxiliary equipment such as condenser, preheater and working medium pump, a complete cycle is formed. Since the auxiliary equipment for flow heat transfer experiment is familiar to those skilled in the art, its function and role will not be repeated here.

[0108] To monitor the temperature changes during heat transfer, multiple temperature measurement elements inside and on the surface of the device record temperature data in real time, which can be transmitted to external monitoring equipment 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 the 3DIC, to obtain more intuitive temperature field information. After the temperature data collected by the temperature measurement elements is transmitted to the computer through the data acquisition device, first, use data filtering algorithms such as Kalman filtering or wavelet transform to remove noise and ensure data accuracy. Subsequently, use MATLAB software to complete the conversion of resistance data to temperature data, and use time domain and frequency domain analysis methods to analyze the trend of temperature change over time to identify the heat transfer characteristics and transient response in the system. Use ANSYS Fluent software and OpenFOAM open source package to simulate the temperature field of the three-dimensional model of this embodiment, and verify it combined with experimental data, analyze the temperature gradient in different regions. The temperature distribution data captured by the infrared thermal imager is optimized through image processing algorithms such as histogram equalization and edge detection to ensure the clarity of the temperature field information. At the same time, through the thermal imaging analysis software (image processing toolbox of MATLAB), the two-dimensional thermal imaging data is converted into a three-dimensional temperature distribution map, to further analyze the local heat conduction of each region.

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

[0110] The following adds specific experimental test steps and numerical simulation to further illustrate the present application:

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

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

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

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

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

[0116] 4. Start the DC controllable direct current power supply equivalent chip heat dissipation working condition, adjust the power consumption of each layer of chip to be consistent, and reach 2W, 4W, 6W in turn, record the change of chip surface temperature and cooling liquid outlet temperature under different power consumption, and focus on observing the phase change behavior of the working medium in the micro-channel;

[0117] 5. Data acquisition, real-time monitoring of 3DIC temperature distribution through patch type temperature measuring element 5 and infrared thermal imager, recording of working medium boiling and gas-liquid two-phase flow state using high-speed camera, recording of pressure and differential pressure data using pressure gauge and differential pressure gauge, and reading of flow data using flowmeter;

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

[0119] Further, the open source program package OpenFOAM is used to simulate the gas-liquid two-phase flow pattern and temperature distribution of HFE7100 under the current working condition. The liquid thermal conductivity of HFE7100 is set to 0.07 W / (m·K), the microchannel thermal conductivity is set to 385 W / (m·K), the liquid flow rate is set to 0.5 m / s, the phase change latent heat is set to 112 kJ / kg, and the surface tension is set to 13.6 mN / m. The calculation results show that under the condition of low power consumption of 2 W, HFE-7100 does not reach the phase change boiling temperature, and the outlet cooling liquid temperature is 36℃. The cooling effect mainly depends on single-phase liquid cooling. When the power consumption increases to 4 W, the chip surface temperature reaches 63℃, and the phase change occurs in some areas of the microchannel. The cooling effect is obviously enhanced, and bubble flow appears. Under the condition of high power consumption of 6 W, HFE-7100 boils in the microchannel, forming stable two-phase flow. The chip surface temperature is controlled within 78℃, and the cooling efficiency is significantly improved. The gas-liquid two-phase flow pattern is mainly annular flow and slug flow, which is consistent with the boiling cooling characteristics under high heat flux.

[0120] The device simulates the real working environment of 3DIC by constructing a heat transfer physical model equivalent to the real 3DIC, designs a feasible flow and heat transfer experimental test scheme, and can provide accurate heat transfer data, which provides a scientific basis for optimization design and performance improvement. For example, the device can be used to evaluate the cooling effect of different cooling liquids, different coolant flow rates, different microchannel structure types, different heat source powers, different heat source sizes and shapes, etc., to help design an efficient cooling system and optimize the numerical model of microscale multi-physical field flow boiling. The embodiment provides a well-designed 3DIC flow and heat transfer test device, which provides a solid foundation for research and development in the related field.

[0121] The above merely describes a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed in the present application can be easily thought of by those skilled in the art, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A 3DIC flow heat transfer testing device, characterized in that, include: A left-side open-type heating element slot and a right-side open-type heating element slot, the top and bottom of the open-type heating element slot having sealed cavity walls, with the opening located on one side and the other side walls sealed. The left-side open-type heating element slot and the right-side open-type heating element slot are alternately stacked in the vertical direction; an MCH ceramic heating element, the length, width, and height of which are consistent with the length, width, and height of the inner cavity of the left-side open-type heating element slot or the right-side open-type heating element slot, the MCH ceramic heating element being installed in the left-side open-type heating element slot or the right-side open-type heating element slot by horizontal insertion; at least one set of microchannel modules, the microchannel modules... Located between two open heating element slots, the microchannel module is tightly fitted to the slots and consists of two spaced-apart left and right sections. Each microchannel module comprises multiple microchannels. An interlayer communication post, cylindrical in shape, is positioned in the center of the two microchannel modules. It has a hollow periphery and is the same height as the microchannel modules, vertically positioned between the two open heating element slots and tightly fitted. A patch-type temperature sensing element is mounted on the wall of the open heating element slot for real-time temperature monitoring. An inflow and outflow interface are located at opposite ends of the device and connected to the circulation pipeline. A flow distributor is connected to the inlet and outlet ports. The flow distributor has a shape with a thin-walled boss or base, transitioning smoothly from a circular cross-section to a rectangular cross-section. The flow distributor contains several fluid distribution guide vanes and an arc-shaped triangular guide structure in the center. The fluid distribution guide vanes are located on both sides of the arc-shaped triangular guide structure and are fixed vertically, on the side of the flow distributor away from the inlet and outlet ports.

2. The apparatus according to claim 1, characterized in that: The length of the microchannel module is the same as the length of the left open heating element slot and the right open heating element slot. The materials of the microchannel include, but are not limited to, graphene-reinforced copper composite material, aluminum nitride ceramic and copper.

3. The apparatus according to claim 1, characterized in that: When using flow boiling heat transfer, the inner wall of the microchannel in the microchannel module undergoes a hydrophilic surface treatment.

4. The apparatus according to claim 1, characterized in that: The MCH ceramic heating element is customized according to the heating characteristics and location of the 3DIC, achieving localized point heating, sheet heating, or irregular pattern heating.

5. The apparatus according to claim 1, characterized in that: The interlayer communication post is a solid cylindrical structure with a base diameter of less than 1 mm and a height-to-diameter ratio not exceeding 5. It is used for heat transfer in the vertical direction between the microbumps and bonding posts of an equivalent real 3DIC. 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 base 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, and F represents the applied force. cr Let E represent the buckling load, K represent the elastic modulus of the material, K represent the empirical parameter of the support condition, and I represent the moment of inertia of the cross section. The calculation method satisfies the following conditions: d represents the diameter of the bottom circle of the interlayer communication column.

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

7. The apparatus according to claim 1, characterized in that: The inlet and outlet ports have the same orifice diameter as the test circulation loop, and the ports are made of transparent material with sufficient temperature resistance.

8. The apparatus 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 transparent material and has sufficient temperature resistance.

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

10. The apparatus according to claim 1, characterized in that: A high-speed camera and supplementary lighting are installed next to the outflow interface, flow distributor, and test circulation pipeline to record the fluid flow process.

11. The apparatus according to claim 10, characterized in that: The working fluid used in the test was treated with fluorescent dye, the flow rate was measured by an electromagnetic flow meter, and a transparent pipe was used.

12. The apparatus according to claim 1, characterized in that: Other equipment included in the testing apparatus includes, but is not limited to, a preheater, a condenser, valves, a resistance temperature sensor, a constant flow pump, and a liquid storage tank.

13. The apparatus according to claim 1, characterized in that: The multiple microchannel modules have different structures. The multiple microchannels are arranged in a single layer or 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 characteristics of multiple microchannels are different.

14. The apparatus according to claim 1, characterized in that: The patch-type temperature sensing element is composed of PT-100 or thermocouple wire with a layer of thermally conductive copper film attached to its surface.

15. The apparatus according to claim 1, characterized in that: The arc-shaped triangular flow guide structure was optimized using CFD, and the arc satisfies the equation 16. A test method for a 3DIC flow heat transfer test apparatus, wherein the measurement is performed using the apparatus described in any one of claims 1-15, characterized in that: Before testing, the outer surface of the device and the inner side of the open-type heating element slot are cleaned and dried. The device is tested for air tightness and water tightness. The MCH ceramic heating element with thermal grease coated on its surface is inserted into the open-type heating element slot to ensure a tight fit without gaps. A patch-type temperature sensing 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 the patch-type temperature sensing element and a thermal imager. A high-speed camera is turned on to take pictures and videos of the fluid movement. After the above steps are completed and the device is running normally, the power output channel is turned on to adjust the power of the MCH ceramic heating element to control the heating amount. The flow heat transfer test of 3DIC under the required heat load and operating 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, noise is removed by Kalman filtering or wavelet transform data filtering algorithm, and the resistance data is converted into temperature data by MATLAB software. Combined with time domain and frequency domain analysis methods, the heat transfer characteristics and transient response of the system are identified; 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 a three-dimensional temperature distribution map is generated by the MATLAB image processing toolbox; the fluid flow state is analyzed by high-speed photography and fluorescence staining combined with optical flow method or PIV technology, the flow pattern is automatically classified by convolutional neural network, and the flow pattern transformation law is analyzed by time series analysis by ARIMA or LSTM model.

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