Self-heating foil for fixing electronic component

Abstract

The invention provides a self-heating foil for fixing an electronic component, and relates to the technical field of connection of different materials, the self-heating foil comprises a plurality of alternately arranged main body layers and at least one auxiliary layer arranged among the plurality of main body layers, each main body layer comprises at least two main body material layers, and the thickness ratio of the auxiliary layer to the main body layer is 1: 2-1: 100. According to the self-heating foil used for fixing the electronic component, the self-heating foil comprises the multiple main body layers arranged alternately and the at least one auxiliary layer arranged between the multiple main body layers, each main body layer comprises the at least two main body material layers, and the auxiliary layers are inserted into the main body layers to eliminate internal stress, so that the self-heating foil can be used for fixing the electronic component. The plasticity of the self-heating foil and the crack resistance of the self-heating foil in the SHS reaction generation process are improved, and stable and firm connection of any element with different materials, space shapes and surface textures is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of joining different materials, and particularly relates to a self-heating foil for fixing electronic components. Background Art

[0002] In the prior art, the known method for joining parts made of different materials (including non-metallic materials) is brazing. There are a wide variety of available solders (classified by type, composition, melting point, and other characteristics), and there are numerous brazing methods: such as induction heating, radiant energy, hot gas, dip brazing, etc. Moreover, the brazing conditions and parameters (such as temperature, holding time, heating and cooling rates, etc.) are variable.

[0003] However, it is not always feasible to obtain a durable and firm connection through traditional brazing methods, which is particularly evident when joining brittle and "complex" materials (such as piezoelectric ceramic materials, parts with textured and / or complex spatial shapes on the surface), small parts (such as integrated circuit components, jewelry accessories), and when joining combinations of the above materials (such as ceramic-metal). The reason for the unsatisfactory connection quality is that it is impossible to flexibly control the variable parameters of the brazing process for a specific connection, that is, to select the optimal thickness of the solder, heating rate, and temperature while taking into account the characteristics of the part materials.

[0004] These problems can be solved to some extent by using a multi-layer self-heating solder, that is, using a structure that includes a solder layer and a reaction layer (self-propagating high-temperature synthesis, i.e., SHS occurs when triggered). In this structure, the solder is heated by the energy released during the SHS reaction process, that is, the energy activated in the reaction layer.

[0005] The problem of controlling reaction kinetics and speed by adopting inner layer structures with different thicknesses is described in the literature Knepper R. et al. Effect of varying bilayer spacing distribution on reaction heat and velocity in reactive Al / Ni multilayers / / Journal of applied physics 105 - 2009 (Literature 1) and Lucadamo G. et al. Microstructure evolution during solid state reactions of Nb / Al multilayers / / Acta Materialia 49, - 2001, P.2813 - 2826. (Literature 2). For example, Literature 1 shows a multi - layer reactive foil made by vacuum deposition method, which contains alternately arranged aluminum (Al) layers and nickel (Ni) layers, and the thickness ratio of Al layer to Ni layer is 3:2 to ensure the average stoichiometric ratio of the foil is Al50Ni46V4; in various schemes, the bilayer thickness range is 10 - 200 nm, and the total thickness range is 5 - 36 μm; Literature 2 shows a multi - layer reactive thin film made of other materials (niobium (Nb) and aluminum (Al)) on a silicon oxide substrate, and the thin film consists of several groups of bilayers with rated thicknesses of 10, 23.2, 54.5, 72, 143 and 333 nm.

[0006] Although the above - mentioned similar structures have a wide range of capabilities for adjusting the thermophysical parameters of SHS reactions, they do not take into account the interaction between layers during the reaction process, which can lead to foil cracking and thermal shock (subsequently causing damage) to the connectors.

[0007] Technologically, the closest is the thin film used for soldering, which can connect different materials, such as integrated circuit components (crystals) to metal, glass or ceramic substrates; the patent application number is CN113894460A, and the patent named "A self - propagating soldering thin film and its preparation method" discloses that the product contains a first solder layer, multi - layer foils and a second solder layer stacked in sequence, where the multi - layer foils contain Ti - Al, Al - Ni layers, and one or more layers of Ti - Ni, Ni - Si, Nb - Si, Al - CuOx, Al - Pt thin layers, and the melting point of the first solder layer and / or the second solder layer is lower than the highest instantaneous triggering temperature of the self - propagating reaction in the multi - layer foils; the thickness of a single - layer foil is 10 - 100 nm, and the total thickness is 10 - 2000 μm. Triggering a self - propagating reaction in the foils, that is, a self - propagating high - temperature synthesis reaction, will instantaneously cause the solder layer to fully melt.

[0008] The disadvantages of the known foils selected as prototypes are that the strength parameters of the brazed welds obtained are unstable, and there are limitations in the combination of available solders and connectable materials. This is because during the brazing process, the foil is subjected to thermal shock, resulting in cracking, that is, it is subjected to thermal energy sufficient to melt the solder but exceeding the tolerance range of the foil; the manner and location (depth, number, and direction) of crack appearance are unpredictable and uncontrollable. Even when the wettability of the surface of the connector is good, once the integrity of the foil layer is damaged, it cannot provide sufficient load-bearing capacity; in addition, even if the cracks are filled with solder, the negative impact of the cracks on the strength of the brazed weld cannot be eliminated because the structure of the foil remains non-uniform and is "broken" by the cracks; the single-crystal structure of the foil layer is destroyed, resulting in the accumulation of internal stress within the layer, ultimately embrittling the entire foil, thereby reducing the brazing strength; the issue of the influence of the foil layer thickness on the mechanical properties of the foil and on the strength characteristics of the connection achieved through the foil has been widely discussed in the prior art. However, the problem of controlling the foil properties by changing the layer thickness has not been fully studied. Summary of the Invention

[0009] The object of the present invention is to overcome the deficiencies existing in the prior art and provide a self-heating foil for fixing electronic components, improving the plasticity of the foil. The self-heating foil can firmly connect any material using different solders while maintaining the functional characteristics of the material.

[0010] The technical solution adopted by the present invention is as follows:

[0011] A self-heating foil for fixing electronic components, wherein the self-heating foil includes a plurality of alternately arranged main layers and at least one auxiliary layer provided between the plurality of main layers. Each main layer includes at least two main material layers, and the thickness ratio of the auxiliary layer to the main layer is 1:2 - 1:100.

[0012] Preferably, for the self-heating foil for fixing electronic components, the materials of the main material layer and the auxiliary layer are each selected from at least one of nickel, aluminum, copper, titanium, silicon, zirconium, silver, vanadium, molybdenum, indium, iron, and the above metal oxides, and the materials of the two main material layers are different.

[0013] Preferably, for the self-heating foil for fixing electronic components, the materials of the main material layer and the auxiliary layer are the same, and the auxiliary layer includes at least two layers.

[0014] Preferably, for the self-heating foil for fixing electronic components, the materials of the main material layer and the auxiliary layer are different.

[0015] Preferably, for the self-heating foil for fixing an electronic component, the main body layer and the auxiliary layer are formed by vacuum deposition, and the vacuum chamber pressure and the sputtering speed when depositing a pair of main body material layers are different from the vacuum chamber pressure and the sputtering speed when depositing the previous pair of main body material layers.

[0016] Preferably, for the self-heating foil for fixing an electronic component, the ratio of the vacuum chamber pressure when depositing a pair of main body material layers to the vacuum chamber pressure when depositing the previous pair of main body material layers is 1:5 - 5:1.

[0017] Preferably, for the self-heating foil for fixing an electronic component, the ratio of the sputtering speed when depositing a pair of main body material layers to the sputtering speed when depositing the previous pair of main body material layers is 1:10 - 2:1.

[0018] Preferably, for the self-heating foil for fixing an electronic component, the unit energy storage value of the self-heating foil is ≥800 J / g.

[0019] Advantages of the present invention:

[0020] (1) For the self-heating foil for fixing an electronic component of the present invention, the self-heating foil includes a plurality of alternately arranged main body layers and at least one auxiliary layer disposed between the plurality of main body layers. Each main body layer includes at least two main body material layers. By inserting the auxiliary layer into the main body layer, the internal stress is eliminated, the plasticity of the self-heating foil and the crack resistance during the SHS reaction are improved, ensuring stable and firm connection of any components with different materials, spatial shapes and surface textures.

[0021] (2) For the self-heating foil for fixing an electronic component of the present invention, the elimination of internal stress is also achieved by adjusting the growth mode of the main body layer and the auxiliary layer during the foil production process, including the selection of the ratio of the vacuum chamber pressure to the sputtering speed when depositing continuously arranged layers. By combining the sputtering speed and the pressure mode within a certain range, the internal stress in the obtained foil can be minimized. Combined with the inserted auxiliary layer, the internal stress in the obtained foil is completely eliminated.

[0022] (3) For the self-heating foil for fixing electronic components of the present invention, the problem of cracking of the multi-layer foil grown by any vacuum deposition method has been well-known. During the growth process of the foil, mechanical stress accumulates in each layer because these growth methods cannot obtain a perfect crystal lattice, and there must be a mismatch in atomic spacing, which leads to the generation of mechanical stress in each layer. If all layers are the same, these stresses will gradually accumulate and eventually cause cracking. The present invention releases these stresses by adding an intermediate layer, thereby forming a structure that does not allow the stress of each layer to accumulate. The present invention proposes two methods to reduce the stress accumulation effect. The first method is to insert auxiliary layers made of the same material as the main material layer, but change the thickness of these auxiliary layers; the second method is to insert auxiliary layers made of other materials. The effects of these two methods are the same, and the auxiliary layers act as buffers to release the stress accumulated in the main layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 FIG. is a schematic structural diagram of the self-heating foil of the present invention.

[0024] Figure 2 FIG. is another schematic structural diagram of the self-heating foil of the present invention.

[0025] Figure 3 FIG. is an X-ray diagram of a self-heating foil specimen with crack-filled tin.

[0026] Figure 4 FIG. is an X-ray diagram of an uncracked self-heating foil specimen.

[0027] Figure 5 FIG. is a schematic structural diagram of a self-heating foil plated with solder. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will be further described below in conjunction with specific embodiments.

[0029] A self-heating foil for fixing electronic components, the self-heating foil includes a plurality of alternately arranged main layers and at least one auxiliary layer disposed between the plurality of main layers, each main layer includes at least two main material layers, and the thickness ratio of the auxiliary layer to the main layer is 1:2 - 1:100.

[0030] The principle of the self-heating foil's operation is the self-propagating high-temperature synthesis reaction (SHS reaction), which is a chemical reaction that forms intermetallic compounds from metals; intermetallic compounds are not alloys but a new crystal structure, and this reaction is accompanied by heat release. To make this reaction occur, at least two different materials are required. In this invention, the materials of the main material layer and the auxiliary layer are each selected from at least one of nickel, aluminum, copper, titanium, silicon, zirconium, silver, vanadium, molybdenum, indium, iron, and the above metal oxides. The materials of the two main material layers are different, the materials of the main material layer and the auxiliary layer are the same, and the auxiliary layer includes at least two layers.

[0031] The materials of the main material layer and the auxiliary layer are each selected from at least one of nickel, aluminum, copper, titanium, silicon, zirconium, silver, vanadium, molybdenum, indium, iron, and the above metal oxides. The materials of the two main material layers are different, and the materials of the main material layer and the auxiliary layer are different.

[0032] The main layer and the auxiliary layer are formed by vacuum deposition. The vacuum chamber pressure and sputtering speed when depositing a pair of main material layers are different from those when depositing the previous pair of main material layers; the ratio of the vacuum chamber pressure when depositing a pair of main material layers to the vacuum chamber pressure when depositing the previous pair of main material layers is 1:5 - 5:1; the ratio of the sputtering speed when depositing a pair of main material layers to the sputtering speed when depositing the previous pair of main material layers is 1:10 - 2:1; the unit energy storage value of the self-heating foil ≥ 800 J / g.

[0033] The problem of cracking in multi-layer foils grown by vacuum deposition methods is well-known. During the growth of the foil, mechanical stress accumulates in each layer because these growth methods cannot obtain a perfect lattice, and there must be mismatches in atomic spacing, which leads to the generation of mechanical stress in each layer. If all the layers are the same, these stresses will gradually accumulate and eventually lead to cracking. By adding intermediate layers, these stresses can be released, thus forming a structure that does not allow the stress to accumulate in each layer. In this application, two methods for reducing the stress accumulation effect are proposed: the first method is to insert auxiliary layers made of the same material as the main layer but change the thickness of these auxiliary layers; the second method is to insert auxiliary layers made of other materials. The effects of these two methods are the same: the auxiliary layer acts as a buffer to release the stress accumulated in the main layer. By understanding the specific stress accumulated in the main layer, the auxiliary layer that can release these stresses can be calculated and inserted.

[0034] The applicant of this invention has experimentally confirmed that the structural characteristics of the self-heating foil used to fix electronic components determine its plasticity and crack resistance during the occurrence of the SHS reaction, which in turn ensures the stable and firm connection of any components with different materials, spatial shapes, and surface textures.

[0035] The optimal parameters of the self-heating foil were demonstrated as follows. For the purpose of demonstration, samples based on nickel, aluminum, copper, titanium, silicon, zirconium, silver, vanadium, indium, molybdenum, iron, and oxides of the above metals were prepared by different methods (vacuum sputtering method, including magnetron sputtering method). The most suitable layer growth modes and parameters were selected for each sample. The samples had different combinations of layer thicknesses: all layers had the same thickness and different thickness layers were inserted, i.e., layers thinner than the main layer of the foil structure. The ratio of the thickness of the thin layer to the thickness of the main foil layer was variable. For some samples (during vacuum deposition), the sputtering pressure and speed of the continuously arranged layers were also adjusted. Then, the SHS reaction of the samples was initiated and the state of the foil was evaluated. Different means were used to initiate the SHS reaction: a spark generated by a DC power supply passed through a small area of the foil (voltage 6 - 12 V); a short-time point contact was made between the soldering iron tip and the small tail end of the foil (soldering iron tip temperature 350 - 600 °C); a laser was used for a short-time point action on a part of the foil (wavelength 0.3 - 10 μm, power 1 - 100 W / min). Then, the crack situation of the samples was evaluated by visual inspection, radiography, and a bending test with a critical curvature radius of 1 cm. The characteristics of some specimens and the evaluation results of the state after the SHS reaction are shown in Table 1.

[0036] Table 1

[0037]

[0038] As can be seen from the data in Table 1, the qualitative composition and structural characteristics of the self-heating foil have a significant impact on the mechanical properties of the foil. The test results of the samples with the same layer thickness (Samples 1 - 7) were not ideal. Specifically, after the bending test with the critical curvature radius and after the SHS reaction, a large number of cracks appeared, and the crack directions were chaotic and the depths were relatively large. In some cases, they were even through cracks (Sample 6). Inserting auxiliary layers with thicknesses different from the main layer can obtain foils with high plasticity and high crack resistance (Samples 8 - 17). At the same time, on the premise of maintaining good crack resistance, the same energy release level of the SHS reaction can be achieved through different foil layer configurations. For example, by uniformly inserting thin layers made of the main material in different layer thickness ratios, almost no cracks can be generated at different foil thicknesses (Samples 8 - 12); the same effect can also be achieved by changing the insertion interval of the auxiliary layer (Samples 16 and 17). In addition, Samples 8 - 12 were replicated several times, but different layer sputtering modes (pressure and speed) were used during sample production. All these samples showed good crack resistance during the SHS reaction and had the best brazed joint strength characteristics.

[0039] The layer schemes given in Table 1 and their distribution in the structure have been tested on different material combinations (not only Al, Ni, Cu, Ti, Ag, Zr), and the influence of the discovered layer thickness ratios on other material combinations (capable of forming self-propagating high-temperature synthesis reactions with each other) to achieve the said technical results is not limited thereby.

[0040] Further research on the samples was carried out by evaluating the strength characteristics of the brazed joints. Tin-based and silver-based solders with various thicknesses (5 - 10 μm) were plated on the replicated samples of foils No. 1 - 17 (each 10 cm × 10 cm). As the parts to be connected by brazing, parts made of different materials were used: metal - metal, ceramic - metal, ceramic - ceramic, crystal - ceramic, crystal - metal, which included thin and brittle crystals (such as quartz, sapphire); the foil was placed between the two parts to be connected, fixed and pressed tightly. After starting the SHS reaction, the obtained connections were tested. The SHS reaction was started by the dot-like action of a short-time current pulse (such as a laser, soldering iron tip) on a part of the foil; the quality of the part connection was evaluated by measuring the shear strength of the brazed joint; the tensile strength limit of the brazed joints of samples No. 1 - 7 did not exceed 20 MPa, and the shear modulus did not exceed 35 MPa; while all the brazed joints of samples No. 8 - 17 had good characteristics: the tensile strength of the brazed joints was between 48 - 72 MPa, and the shear modulus was between 50 - 75 MPa.

[0041] In addition, strength tests were also carried out to achieve connection by melting the surface of the parts only through activating the SHS reaction of the foil without using solder. The characteristics of such connections were also within good index ranges: the tensile strength was between 55 - 60 MPa, and the shear modulus was between 50 - 60 MPa.

[0042] The realization of the technical achievement is attributed to the elimination of the internal stress generated during the production process. The magnitude of the internal stress is proportional to the number of layers of the foil. The more layers there are, the greater the internal stress. The elimination of the internal stress is achieved by inserting auxiliary layers of different thicknesses in the structure of the foil, that is, in the transverse direction of the foil. The frequency and numerical variation of the different thicknesses depend on the total thickness range of the foil. The self-heating foil with different thicknesses is achieved by inserting one or more auxiliary layers. The auxiliary layer can be made of the same material as the main layer or other materials. However, the thickness ratio of the auxiliary layer to the main layer is crucial and should be within the range of 1:2 - 1:100. At the same time, the arrangement frequency of the main layer and the auxiliary layer with different thicknesses can be diverse: regular or variable. Regular means that the main layer and the auxiliary layer with different thicknesses are arranged at a certain rhythm and interval. For example, the auxiliary layer is inserted every 10 pairs of the main material layers. Variable means that the main layer and the auxiliary layer with different thicknesses are arranged at uneven intervals. For example, the auxiliary layer is inserted 5 times every 10 pairs of the main material layers, then 7 times every 12 pairs of the main material layers, and then 10 times every 15 pairs of the main material layers.

[0043] The elimination of the internal stress can also be achieved by adjusting the growth mode of each layer (the main layer and the auxiliary layer) during the foil production process, including the selection of the ratio of the vacuum chamber pressure to the sputtering speed when depositing continuously arranged layers. Combining the sputtering speed and the pressure mode within a certain range can minimize the internal stress in the obtained foil. Coupled with the inserted auxiliary layer, the internal stress in the foil is completely eliminated.

[0044] The present invention is illustrated by the accompanying drawings, in which Figure 1 is a schematic structural diagram of a self-heating foil, and both its main layer and auxiliary layer are made of a pair of materials M1 + M2; Figure 2 is another schematic structural diagram of a self-heating foil, in which the main layer is made of a pair of materials M1 + M2, and the auxiliary layer is made of a third material M3; Figure 3 is an X-ray diagram of a self-heating foil specimen of sample No. 3 with crack-filled tin (appearing as a darker area) (the thickness of all layers in these foil samples is the same); Figure 4 is an X-ray diagram of a non-cracked self-heating foil specimen of sample No. 11; Figure 5 is a schematic structural diagram of a self-heating foil plated with solder, Figure 5 in which 4 is solder and 5 is the self-heating foil.

[0045] Figure 1The self-heating foil includes a large number of alternately arranged main layers and at least two auxiliary layers. The main layer includes a first main material layer 1 made of material M1 and a second main material layer 2 made of material M2. The auxiliary layer is made of the same material as the main layer, and the thickness of the auxiliary layer is different from that of the main layer. d1 represents the thickness of the first main material layer 1 made of material M1, and d2 represents the thickness of the auxiliary layer made of material M1. At the same time, each layer maintains the alternating order of materials during arrangement. By changing the thickness of the auxiliary layer while keeping the materials of the main layer and the auxiliary layer the same, stress accumulation can be eliminated and the mechanical properties can be improved.

[0046] Figure 2 The self-heating foil includes a large number of alternately arranged main layers and one or more auxiliary layers. The main layer includes a first main material layer 1 made of material M1 and a second main material layer 2 made of material M2. The first main material layer 1 is made of material M1, and the second main material layer 2 is made of material M2. The auxiliary layer is made of a third material M3.

[0047] The self-heating foil includes a large number of alternately arranged main layers and one or more auxiliary layers. The main layer includes a first main material layer 1 made of material M1 and a second main material layer 2 made of material M2. The first main material layer 1 is made of material M1, and the second main material layer 2 is made of material M2. The auxiliary layer is made of a third material M3, or the auxiliary layer is made of a third material M3 and a fourth material Μ4.

[0048] That is to say, the material combination used in the self-heating foil can consist of only a pair of materials, or can consist of three, four or more materials.

[0049] The thickness ratio of the auxiliary layer to the main layer is between 1:2 and 1:100. At the same time, considering the thickness of all layers, the unit energy storage value of the self-heating foil is not less than 800 J / g.

[0050] Figure 3 To show the situation where the self-heating foil of sample No. 3 has cracks, from Figure 3 it can be seen that if no measures are taken and no auxiliary layer is added during the growth of the multi-layer foil, it will definitely crack. Figure 4 To show the situation where the self-heating foil of sample No. 11 has no cracks, from Figure 4 it can be seen that by inserting an auxiliary layer to change the structural parameters, the mechanical properties of the foil are changed, the plasticity of the foil is improved, and the self-heating foil will no longer crack. The cracking of the self-heating foil is a very unfavorable factor for the connection strength. Through the present invention, we have improved the plasticity of the foil, reduced the cracking, and thus improved the strength of the final connection.

[0051] Example 1

[0052] A self-heating foil was prepared to connect ceramic parts and metal parts. The main body layer includes a first main body material layer and a second main body material layer. The material of the first main body material layer is aluminum, and the material of the second main body material layer is nickel. The thickness of the first main body material layer is 30 nm, and the thickness of the second main body material layer is 20 nm. An aluminum-nickel auxiliary layer is provided every 100 layers of the main body layer. The thickness of the auxiliary layer Al is 3 nm, and the thickness of the auxiliary layer Ni is 2 nm. The thickness ratio of the auxiliary layer to the main body layer is 1:10. The main body layer and the auxiliary layer are formed by vacuum deposition. The vacuum chamber pressure and sputtering speed when depositing a pair of main body material layers are different from those when depositing the previous pair of main body material layers. The ratio of the vacuum chamber pressure when depositing a pair of main body material layers to the vacuum chamber pressure when depositing the previous pair of main body material layers is 1:3, and the ratio of the sputtering speed when depositing a pair of main body material layers to the sputtering speed when depositing the previous pair of main body material layers is 1:8.

[0053] In this embodiment, tin-based and silver-based solders with a thickness of 10 μm were used, and the characteristics of the brazed joint are as follows: the tensile strength of the joint is 30 MPa, and the shear modulus of the connection is 53 MPa.

[0054] Example 2

[0055] A self-heating foil was prepared to connect ceramic parts and ceramic parts. The main body layer includes a first main body material layer and a second main body material layer. The material of the first main body material layer is aluminum, and the material of the second main body material layer is nickel. The thickness of the first main body material layer is 45 nm, and the thickness of the second main body material layer is 30 nm. A titanium auxiliary layer with a thickness of 7.5 nm is provided every 80 layers of the main body layer. The thickness ratio of the auxiliary layer to the main body layer is 1:10. The main body layer and the auxiliary layer are formed by vacuum deposition. The vacuum chamber pressure and sputtering speed when depositing a pair of main body material layers are different from those when depositing the previous pair of main body material layers. The ratio of the vacuum chamber pressure when depositing a pair of main body material layers to the vacuum chamber pressure when depositing the previous pair of main body material layers is 1:5, and the ratio of the sputtering speed when depositing a pair of main body material layers to the sputtering speed when depositing the previous pair of main body material layers is 1:4.

[0056] The characteristics of the brazed joint obtained in this embodiment are as follows: the tensile strength of the joint is 40 MPa, and the shear modulus of the connection is 55 MPa.

[0057] Example 3

[0058] A self-heating foil was prepared to connect a crystal and a metal part. The main body layer includes a first main body material layer and a second main body material layer. The material of the first main body material layer is aluminum, and the material of the second main body material layer is nickel. The thickness of the first main body material layer is 60 nm, and the thickness of the second main body material layer is 40 nm. And a titanium auxiliary layer with a thickness of 10 nm is provided every 50 main body layers. The thickness ratio of the auxiliary layer to the main body layer is 1:10. The main body layer and the auxiliary layer are formed by vacuum deposition. The vacuum chamber pressure and sputtering speed when depositing a pair of main body material layers are different from those when depositing the previous pair of main body material layers. The ratio of the vacuum chamber pressure when depositing a pair of main body material layers to the vacuum chamber pressure when depositing the previous pair of main body material layers is 2:1. The ratio of the sputtering speed when depositing a pair of main body material layers to the sputtering speed when depositing the previous pair of main body material layers is 1:1.

[0059] In this embodiment, tin-based and silver-based solders with a thickness of 10 μm were used. The characteristics of the brazed joint are as follows: the tensile strength of the joint is 45 MPa, and the shear modulus of the connection is 60 MPa.

[0060] Example 4

[0061] A self-heating foil was prepared to connect a metal part and a metal part. The main body layer includes a first main body material layer and a second main body material layer. The material of the first main body material layer is vanadium, and the material of the second main body material layer is zirconium. The thickness of the first main body material layer is 60 nm, and the thickness of the second main body material layer is 60 nm. And a silver auxiliary layer with a thickness of 12 nm is provided every 100 main body layers. The thickness ratio of the auxiliary layer to the main body layer is 1:10. The main body layer and the auxiliary layer are formed by vacuum deposition. The vacuum chamber pressure and sputtering speed when depositing a pair of main body material layers are different from those when depositing the previous pair of main body material layers. The ratio of the vacuum chamber pressure when depositing a pair of main body material layers to the vacuum chamber pressure when depositing the previous pair of main body material layers is 2:1. The ratio of the sputtering speed when depositing a pair of main body material layers to the sputtering speed when depositing the previous pair of main body material layers is 1:3.

[0062] The characteristics of the brazed joint obtained in this embodiment are as follows: the tensile strength of the joint is 48 MPa, and the shear modulus of the connection is 60 MPa.

[0063] Example 5

[0064] To connect the crystal to the crystal preparation, a self-heating foil was prepared. The main body layer includes a first main body material layer and a second main body material layer. The material of the first main body material layer is titanium, and the material of the second main body material layer is aluminum. The thickness of the first main body material layer is 80 nm, and the thickness of the second main body material layer is 80 nm. And a molybdenum auxiliary layer with a thickness of 8 nm is provided every 100 main body layers. The thickness ratio of the auxiliary layer to the main body layer is 1:20. The main body layer and the auxiliary layer are formed by vacuum deposition. The vacuum chamber pressure and sputtering speed when depositing a pair of main body material layers are different from those when depositing the previous pair of main body material layers. The ratio of the vacuum chamber pressure when depositing a pair of main body material layers to the vacuum chamber pressure when depositing the previous pair of main body material layers is 1:4. The ratio of the sputtering speed when depositing a pair of main body material layers to the sputtering speed when depositing the previous pair of main body material layers is 1:5.

[0065] The characteristics of the brazed joint obtained in this embodiment are as follows: the tensile strength of the weld is 49 MPa, and the shear modulus of the joint is 58 MPa.

[0066] Example 6

[0067] To connect two metal parts without using solder, a self-heating foil was prepared. The main body layer includes a first main body material layer and a second main body material layer. The material of the first main body material layer is titanium, and the material of the second main body material layer is aluminum. The thickness of the first main body material layer is 50 nm, and the thickness of the second main body material layer is 50 nm. And a titanium-aluminum auxiliary layer is provided every 100 main body layers. The thickness of the Ti in the auxiliary layer is 5 nm, and the thickness of the Al in the auxiliary layer is 5 nm. The thickness ratio of the auxiliary layer to the main body layer is 1:10. The main body layer and the auxiliary layer are formed by vacuum deposition. The vacuum chamber pressure and sputtering speed when depositing a pair of main body material layers are different from those when depositing the previous pair of main body material layers. The ratio of the vacuum chamber pressure when depositing a pair of main body material layers to the vacuum chamber pressure when depositing the previous pair of main body material layers is 1:1. The ratio of the sputtering speed when depositing a pair of main body material layers to the sputtering speed when depositing the previous pair of main body material layers is 1:10.

[0068] The characteristics of the brazed joint obtained in this embodiment are as follows: the tensile strength of the weld is 50 MPa, and the shear modulus of the joint is 53 MPa.

[0069] From the test results of Examples 1 - 6, it can be obtained that the present invention provides a self-heating foil that is plastic and not prone to cracking during the SHS reaction, and can firmly connect any material using different solders while maintaining the functional characteristics of the material.

[0070] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A self-heating foil for fixing electronic components, characterized in that The self-heating foil comprises multiple alternating main layers and at least one auxiliary layer arranged between the multiple main layers, each of the main layers comprises at least two main material layers, and the thickness ratio of the auxiliary layer to the main layer is 1:2-1:

100.

2. The self-heating foil for fixing electronic components according to claim 1, characterized in that The materials of the main material layer and the auxiliary layer are both selected from nickel, aluminum, copper, titanium, silicon, zirconium, silver, vanadium, molybdenum, indium, iron and at least one of the above metal oxides, and the materials of the two main material layers are different.

3. The self-heating foil for fixing electronic components according to claim 2, characterized in that The main material layer and the auxiliary layer are made of the same material, and the auxiliary layer includes at least two layers.

4. The self-heating foil for fixing electronic components according to claim 2, characterized in that The main material layer and the auxiliary layer are made of different materials.

5. The self-heating foil for fixing electronic components according to claim 1, characterized in that The main layer and the auxiliary layer are formed by vacuum deposition, and the vacuum chamber pressure and sputtering speed when vacuum depositing a pair of main material layers are different from the vacuum chamber pressure and sputtering speed when depositing the previous pair of main material layers.

6. The self-heating foil for fixing electronic components according to claim 5, characterized in that The ratio of the vacuum chamber pressure during vacuum deposition of a pair of main material layers to the vacuum chamber pressure during deposition of the previous pair of main material layers is 1:5-5:

1.

7. The self-heating foil for fixing electronic components according to claim 5, characterized in that The ratio of the sputtering speed when vacuum depositing a pair of host material layers to the sputtering speed when depositing the previous pair of host material layers is 1:10-2:

1.

8. The self-heating foil for fixing electronic components according to claim 1, characterized in that The unit energy storage value of the self-heating foil is ≥800J / g.

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