Adhesive, rotating electrical machine, electronic component, and aircraft

Abstract

An epoxy resin-based matrix adhesive is constituted using an epoxy resin compound having an allyl group with a functionality of greater than or equal to 2 as a main agent, using an amine-based curing agent having a resin skeleton of bisphenol A type, and a stress relaxation agent is constituted by including at least either one of an ethylene-acrylic acid copolymer and an ethylene-propylene copolymer with an average particle diameter of less than or equal to 10 μm in a range of less than or equal to 20 wt% with respect to the matrix adhesive (101).

Description

Technical Field

[0001] This application relates to adhesives, rotating electrical machines, electronic components, and aircraft. Background Technology

[0002] Generally speaking, adhesives with high heat resistance tend to become brittle after curing, resulting in issues such as low adhesive strength. Furthermore, if thermal stress is applied due to temperature cycling, issues such as decreased adhesive strength leading to cracking or peeling from the adherends can arise. Even epoxy resin adhesives, touted as heat-resistant, only have a heat resistance of around 180°C, but in recent years, adhesives with heat resistance exceeding 200°C have begun to appear on the market.

[0003] In contrast, epoxy resin adhesives with excellent heat resistance and a good balance of overlap shear bond strength and peel strength have been disclosed for use in automotive components, etc. (for example, see Patent Document 1). Furthermore, cured compositions with high glass transition temperatures, i.e., high heat resistance, excellent adhesion, and effective adhesive properties have been disclosed (for example, see Patent Document 2).

[0004] Patent Document 1: Japanese Patent No. 6612498

[0005] Patent Document 2: International Publication No. 2017 / 170881 Summary of the Invention

[0006] On the other hand, the high-temperature heat resistance of electronic materials and driving components such as electric motors was studied. For adhesives that bond components, higher heat resistance and stability under a wider range of ambient temperature changes (temperature cycling) are also required.

[0007] The epoxy resin adhesive described in Patent Document 1 constitutes a matrix of liquid epoxy resin containing at least 50% by mass of greater than or equal to 50% trifunctional epoxy resin. The core-shell toughening agent added as a stress reliever also contains a substance with a low glass transition temperature (Tg) (-110 to -30°C). Therefore, it cannot be said to have a structure with sufficient heat resistance. In addition, the resistance to temperature cycling (thermal shock resistance) is not described and is unclear.

[0008] The cured composition described in Patent Document 2 may be said to have high heat resistance for applications such as optical materials, display elements, and various films for electronic components described in the document (paragraph 0099). However, the glass transition temperature Tg is about 80 to 100°C (Tables 1 to 3), so it cannot be said to have sufficiently high heat resistance. In addition, the resistance to temperature cycling (thermal shock resistance) is not described and is unclear.

[0009] This application discloses a technique for solving the above-mentioned problems, with the aim of providing a stress-relieving adhesive that has high heat resistance and is also resistant to stress during temperature cycling.

[0010] The adhesive disclosed in this application uses an epoxy resin compound having an allyl group with greater than or equal to two functional groups as the main agent, and uses an amine curing agent having a bisphenol A type resin skeleton to form an epoxy resin matrix adhesive. As a stress reliever, at least one of an ethylene-acrylic acid copolymer and an ethylene-propylene copolymer with an average particle diameter of less than or equal to 10 μm is included in the matrix adhesive in a range of less than or equal to 20 wt%.

[0011] The effects of the invention

[0012] According to the adhesive disclosed in this application, in the combination of the adhesive in the matrix and the stress reliever added to the adhesive, the Young's modulus on the low-temperature side can be reduced, and since the glass transition temperature does not change, it is configured to be resistant in a way that maintains the high heat resistance of the matrix adhesive and relieves the stress during temperature changes. By using this adhesive, the reliability of the bonded part is improved. Attached Figure Description

[0013] Figure 1 This is a schematic diagram showing the structure of the stress-relieving adhesive involved in Embodiment 1.

[0014] Figure 2 This is a diagram illustrating a method for evaluating the adhesive strength of the stress-relieving adhesive involved in Embodiment 1.

[0015] Figure 3 This is a graph showing the relationship between the amount of stress reliever added and the bond strength of the stress-relieving adhesive involved in Embodiment 1.

[0016] Figure 4A It means Figure 2 A schematic diagram of the fracture modes after the shear test involved.

[0017] Figure 4B It means Figure 2 Schematic diagram of other fracture modes after the shear test involved.

[0018] Figure 5 This graph shows the changes in bond strength when different stress-relieving agents are added to three different matrix adhesives.

[0019] Figure 6 This is a graph showing the temperature dependence of tanδ when the amount of stress reliever added changes in the stress-relieving adhesive according to Embodiment 1.

[0020] Figure 7 This is a graph showing the temperature dependence of Young's modulus when the amount of stress reliever added changes in the stress-relieving adhesive according to Embodiment 1.

[0021] Figure 8 This is a graph showing the change in bond strength of the stress-relieving adhesive before and after the temperature cycling test of the adhesive involved in Embodiment 1.

[0022] Figure 9 This is a schematic diagram showing the structure of the stress-relieving adhesive involved in Embodiment 2.

[0023] Figure 10A This is a partial cross-sectional view showing the structure of an example of a rotary electric machine according to Embodiment 3, namely an IPM electric motor.

[0024] Figure 10B This is a partial cross-sectional view showing the structure of an example of a rotary electric motor involved in Embodiment 3, namely an SPM electric motor.

[0025] Figure 11 This is a cross-sectional view showing the structure of an example of an electronic component involved in Embodiment 4, namely a semiconductor device.

[0026] Figure 12 This is a block diagram illustrating the airflow related to the in-flight air conditioning of the aircraft according to Embodiment 5. Detailed Implementation

[0027] The present embodiment will now be described with reference to the accompanying drawings. Furthermore, in each drawing, the same reference numerals denote the same or equivalent parts.

[0028] Implementation method 1.

[0029] The adhesive involved in Embodiment 1 will now be described.

[0030] [Adjustment of adhesive]

[0031] The adhesive involved in this embodiment 1 is a thermosetting epoxy resin adhesive. The main component, epoxy resin, is a thermosetting component, and an epoxy resin compound having two or more functional allyl groups is used as the main agent. The main agent can be one or a combination of two or more compounds. The curing agent is an amine curing agent having a bisphenol A type resin backbone. The adhesive having the main agent and curing agent constitutes a matrix. Furthermore, relative to the adhesive having the epoxy resin compound as the main agent and the amine curing agent as the matrix, i.e., the epoxy resin adhesive, at least one of ethylene-acrylic acid copolymer and ethylene-propylene copolymer is added as a stress-relieving agent to constitute a stress-relieving adhesive.

[0032] Here, the ethylene-acrylic acid copolymers used as stress relievers are ethylene dimethacrylate, hexamethylene diacrylate, tetramethylene dimethyl methacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, 1,3-butanediol diacrylate, etc.

[0033] In addition, ethylene-propylene copolymers used as stress relievers include propylene glycol diacrylate, tripropylene glycol diacrylate, 2-hydroxypropyl methacrylate, dipropylene glycol diacrylate, and tripropylene acrylate.

[0034] Furthermore, a key feature is that the materials used in these stress-relieving agents have a melting point of approximately 40–100°C.

[0035] Table 1 below shows an example of the adhesive involved in Embodiment 1. An epoxy resin compound having two allyl groups with greater than or equal to two functional groups, namely 4,4'-isopropylidene bisphenol and p-phenyl diisocyanate, is used as the main agent. An amine curing agent having a bisphenol A type resin backbone, namely N,N-diurethane (2,3-epoxypropyl)-4-(2,3-epoxypropoxy)aniline, is used as the additive. An epoxy resin adhesive constituting the matrix is ​​created by adding less than 20 wt% of three stress-relieving agents containing an ethylene-acrylic acid copolymer, namely triethylene glycol dimethacrylate. Amorphous silica is added in a range of less than 5 wt% as a viscosity adjuster and adhesive film thickness adjuster, and the mixture is adjusted to a total of 100 wt%. Furthermore, the main agent, additives, curing agents, etc., are examples and are not limited thereto. For example, if it is the main agent, an epoxy resin compound having two functional groups with greater than or equal to two functional groups can be used.

[0036] Table 1

[0037] Table 1

[0038]

[0039] exist Figure 1 The diagram shows the structure of the stress-relieving adhesive according to Embodiment 1. The stress-relieving adhesive 101, after adjustment and curing, is as follows... Figure 1 As shown, it has a structure in which stress reliever 2 is dispersed in epoxy resin adhesive 1 in the matrix.

[0040] [Creating a shear test piece]

[0041] Next, in order to evaluate the bond strength, shear strength test specimens were created.

[0042] exist Figure 2The method for creating a shear test piece and conducting a shear test are shown. The test piece consists of two SPCC plates 102 (steel plates) arranged in a group. A stress-relieving adhesive 101 is applied to one end of one side of each SPCC plate 102, and the two SPCC plates 102 are sandwiched together. After curing the test piece at 160–200°C, as shown... Figure 2 As shown, shear tests are conducted to evaluate the bond strength by stretching the material upwards and downwards.

[0043] In creating the test piece for evaluating adhesive strength, the surface treatment of the test piece, SPCC board 102, included physical treatments such as atmospheric plasma treatment, deep ultraviolet light treatment, corona discharge treatment, and roughening treatment (laser roughening, grinding, and sandblasting). This is expected to improve adhesion or adhesive strength. Alternatively, applying a chemical treatment using a silane coupling agent as a primer yields the same results. For example, for epoxy resin adhesives, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldioxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride can be used as primers.

[0044] [Evaluation of Bond Strength 1]

[0045] Stress relievers such as Figure 1 As shown, the stress-relieving adhesive 101 is dispersed, but this stress-relieving agent can be used as long as the average particle size is less than or equal to 50 μm. If the average particle size is continuously reduced to a few μm less than or equal to 10 μm, the adhesive strength is improved. That is, the average particle size is preferably in the range of greater than or equal to 1 μm and less than or equal to 10 μm.

[0046] Figure 3 This is a graph showing the relationship between the amount of stress reliever added and the bond strength. The conditions for Comparative Example 1 and Example 1 are described below. Furthermore, the pretreatment conditions were the same.

[0047] <Comparative Example 1>

[0048] • Test piece: SPCC / SPCC

[0049] • Pretreatment of test pieces: degreasing with acetone, grinding with a 400-grit polishing wheel

[0050] • Adhesive thickness: 80–100 μm

[0051] • Adhesive: Main component • Bisphenol A type epoxy resin

[0052] Curing agent... polyamide

[0053] Stress relievers - ethyl carbamates

[0054] <Example 1>

[0055] • Test piece: SPCC / SPCC

[0056] • Pretreatment of test pieces: degreasing with acetone, grinding with a 400-grit polishing wheel

[0057] • Adhesive thickness: 80–100 μm

[0058] • Adhesive: Main component... Epoxy resin compound with allyl groups having greater than or equal to two functional groups.

[0059] Curing agents are amines with a bisphenol A resin backbone.

[0060] Stress reliever - ethylene-acrylic acid copolymer

[0061] The average particle size of the stress reliever is 10 μm.

[0062] Figure 3 The figure shows the change in bond strength when the bond strength without stress reliever is set to 1. In the figure, the stress-relieving adhesive of Example 1 is shown by a solid line, but no decrease in strength is observed when the amount of stress reliever added is increased up to a concentration of 20 wt%. On the other hand, in the adhesive of Comparative Example 1, the strength gradually decreases with the addition of stress reliever, and the strength decreases significantly if the concentration exceeds 10 wt%. Furthermore, the epoxy resin adhesive of Example 1 before the addition of stress reliever (an adhesive used as a matrix, equivalent to...) Figure 3 The stress reliever (0 wt%) showed a bond strength of 16–18 MPa in the above shear test.

[0063] Next, the fracture mode of the test piece from Example 1 after shearing was confirmed.

[0064] Figure 4A and Figure 4B This is a schematic diagram used to illustrate the fracture modes of adhesives after shear tests. Figure 4A This illustrates an interface delamination pattern 104 in which adhesive residue remains on one test piece, namely SPCC plate 102, and delamination occurs at the interface between the other test piece, namely SPCC plate 102 and the adhesive. Figure 4BThe state of the adhesive before and after testing is shown with the addition of the stress-relieving agent 2 involved in this embodiment. Figure 4B In the middle, the fracture occurs inside the adhesive, and the adhesive remains in the two test pieces, namely SPCC plate 102, in the coagulation failure mode 103.

[0065] exist Figure 3 In Example 1, when the amount of stress reliever added was 0, the fracture mode after the test was interfacial delamination. However, with continuous addition of stress reliever, the proportion of cohesive failure in the fracture mode increased, confirming a change in the mode. At a stress reliever concentration of 20 wt%, the fracture mode largely exhibited cohesive failure. This demonstrates that at concentrations less than or equal to 20 wt%, without reducing bond strength, a stress-relieving effect is achieved, and cohesive failure is occurring. Based on the observed fracture modes and Figure 3 It can be seen that the preferred concentration of the stress reliever is 10-20 wt%, which is effective in relieving stress.

[0066] The epoxy resin adhesive (matrix adhesive) in Example 1 above, before the addition of the stress reliever, is a high-heat-resistant epoxy resin adhesive with a cured adhesive strength of 16-18 MPa and a glass transition temperature greater than or equal to 200°C. According to... Figure 3 It can be seen that the stress-relieving adhesive of Example 1 does not reduce the adhesive strength up to an addition concentration of 20 wt%, and even at 30 wt%, the adhesive strength is maintained at 10 MPa, which is an effective stress-relieving adhesive.

[0067] In Example 1, an example of adding only one type of stress reliever is shown, but if it is the same type, two or more types can also be added simultaneously. The smaller the average particle size (size) of the added stress reliever, the more finely it is dispersed throughout the adhesive, and the higher the stress-relieving effect. With the same amount added, the smaller the average particle size of the added stress reliever, the higher the cohesion-damaging effect.

[0068] [Evaluation of Bond Strength 2]

[0069] Next, different types of adhesives were prepared for use with the adhesive before the addition of the stress reliever, and the effect of the stress reliever involved in Embodiment 1 was confirmed.

[0070] The matrix adhesive and stress reliever used are described below.

[0071] Matrix adhesive B1: High heat-resistant epoxy resin

[0072] Main component: epoxy resin compound with difunctional allyl groups

[0073] Curing agents...amines with a bisphenol A resin backbone

[0074] Matrix adhesive B2:1 liquid thermosetting epoxy resin

[0075] ···TB2237J manufactured by Sanbon Co., Ltd.

[0076] Matrix adhesive B3: 2-component acrylic

[0077] ···Y612Black made by Shi Min Hardware Co., Ltd.

[0078] Stress reliever SL1: ethyl carbamate

[0079] Stress reliever SL2: Ethylene-acrylic acid copolymer

[0080] Stress reliever SL3: Ethylene-propylene copolymer

[0081] Figure 5 The changes in bond strength before and after the addition of 10 wt% stress reliever (SL1, SL2, SL3) for each substrate adhesive (B1, B2, B3) are shown.

[0082] The six bars on the left side of the figure serve as a comparative example, showing the addition of urethane stress reliever SL1. Regardless of the substrate adhesive, the bond strength decreased after its addition.

[0083] The six bars in the center of the figure include an example of this embodiment: stress reliever SL2, an ethylene-acrylic acid copolymer. When added to the matrix adhesive B1, a high-heat-resistant epoxy resin, as described in this embodiment, the bond strength is slightly increased; however, when added to other matrix adhesives B2 and B3 as comparative examples, the bond strength decreases.

[0084] The six bars on the right side of the figure include an example of this embodiment: the stress reliever SL3, an ethylene-propylene copolymer. When added to the matrix adhesive B1, a high-heat-resistant epoxy resin, as described in this embodiment, the bond strength is slightly increased; however, when added to other matrix adhesives B2 and B3 as comparative examples, the bond strength decreases.

[0085] As described above, it has been determined that at least one of the stress-relieving agents of the ethylene-acrylic acid copolymer and the stress-relieving agents of the ethylene-propylene copolymer described in Embodiment 1 can be added to the matrix adhesive, i.e., the high heat-resistant epoxy resin, according to Embodiment 1.

[0086] [Changes in glass transfer temperature]

[0087] Next, the change in glass transition temperature caused by the addition of stress relievers will be explained. Glass transition temperature (Tg) is a physical property value that serves as an indicator of heat resistance. Generally, stress relievers are soft materials with low glass transition temperatures; therefore, by adding them to the adhesive matrix, the glass transition temperature of the adhesive decreases accordingly with the amount added.

[0088] In the combination of the matrix adhesive and stress reliever described in Embodiment 1, dynamic viscoelasticity (DMA) tests were conducted within a concentration range where the adhesive strength did not decrease even with the addition of the stress reliever. Here, the combination of matrix adhesive B1 and stress reliever SL2 was evaluated. The temperature dependence of tanδ (loss tangent) and Young's modulus (E') are shown below as the measurement results.

[0089] Figure 6 This is a tanδ curve representing the temperature dependence of tanδ when the horizontal axis is set to temperature and the vertical axis is set to tanδ, and the amount of matrix adhesive B1 and stress reliever SL2 added varies. Figure 6 In the study, the glass transition temperature from the peak value of tanδ to that of the matrix adhesive B1 and the stress reliever SL2 with 20 wt% added to the matrix adhesive B1 was approximately 240°C. No change was observed even when stress reliever SL2, which has a glass transition temperature of 40–100°C and is lower than that of the matrix adhesive, was added.

[0090] That is, in the combination of the adhesive and stress reliever of the matrix involved in Embodiment 1, it is known that even if the stress reliever is added within the range where the adhesive strength is not reduced, the high heat resistance of the matrix adhesive will be maintained.

[0091] [Changes in Young's modulus]

[0092] Figure 7 This is a graph showing the temperature dependence of Young's modulus as the amount of matrix adhesive B1 and stress reliever SL2 added varies. Figure 7 In this process, if stress reliever SL2 is continuously added to the base adhesive B1, the Young's modulus decreases accordingly with the amount added. Specifically, at temperatures below or equal to 150°C, adding 20 wt% of stress reliever SL2 reduces the Pa from several GPa to less than or equal to 1 GPa, down to approximately one-fifth. This reduction in Young's modulus in the low-temperature region alleviates stress during thermosetting and provides the adhesive with resistance to use in environments with significant temperature differences.

[0093] Figure 8This graph shows the changes in bond strength before and after temperature cycling tests for base adhesive B1 and base adhesive B1 with the addition of 20 wt% stress reliever SL2. Here, the temperature cycling test was conducted for 100 cycles within the range of -10°C to 130°C. Furthermore, the bond strength is shown as a change when the initial value is set to 1. The addition of 20 wt% stress reliever SL2 suppresses the decrease in bond strength after temperature cycling tests and demonstrates tolerance to stress during temperature cycling. Additionally, the stress-relieving adhesive with the addition of 20 wt% stress reliever SL2 maintains the coagulation failure mode after temperature cycling tests, indicating a potential improvement in reliability.

[0094] As described above, according to Embodiment 1, an epoxy resin compound having a difunctional allyl group is used as the main agent, and an amine curing agent having a bisphenol A type resin skeleton is used to form an epoxy resin matrix adhesive. As a stress reliever, at least one of an ethylene-acrylic acid copolymer and an ethylene-propylene copolymer with an average particle diameter of less than or equal to 10 μm is added to the matrix adhesive in a range of less than or equal to 20 wt%. Therefore, it is possible to provide an epoxy resin matrix adhesive with high heat resistance and adhesive strength that maintains a glass transition temperature of greater than or equal to 200°C, and a stress-relieving adhesive that has resistance to temperature cycling by reducing Young's modulus.

[0095] Implementation method 2.

[0096] The adhesive involved in Embodiment 2 will now be described.

[0097] [Viscosity Adjustment]

[0098] The stress-relieving adhesive described in Embodiment 1 above controls the particle size of the added stress-relieving agent to be in the range of 1 μm to 10 μm, thereby allowing for viscosity adjustment to obtain an adhesive with a viscosity of 3 Pas to 300 Pas. If the viscosity is within this range, it can maintain a viscosity that prevents sagging when applied to a wall surface. Furthermore, when used in narrow gaps, the viscosity can be adjusted by reducing it. This allows for the production of adhesives with higher thixotropic properties the smaller the particle size.

[0099] The viscosity of an adhesive can be adjusted not only by the particle size of the stress reliever, but also by the materials of the base adhesive, the type and particle size of the stress reliever, and the presence and method of surface treatment when applying it to the substrate. Furthermore, it can also be adjusted by adding fillers.

[0100] [Addition of filler]

[0101] To adjust the viscosity to a range of 3 Pas to 300 Pas, fillers can be added from a selection of materials, including fused silica, amorphous silica, glass such as insulated glass, minerals composed of silicates such as mica and talc, and engineering polymers such as polyethylene and polypropylene. The appropriate filler should be chosen based on factors such as cost and weight reduction.

[0102] For example, in applications such as semiconductors and other electronic components, molten silica is added as a filler to ensure insulation. To improve thermal conductivity, powders (in flake, spherical, needle-like, and special shapes) of materials with high thermal conductivity, such as boron nitride (BN), alumina (Al2O3), aluminum nitride (AlN), and silver (Ag), can be added as fillers. By adjusting the amount added, a binder with the desired thermal conductivity can be manufactured. Furthermore, to improve electrical conductivity, silver or carbon (C) materials can be added.

[0103] The thermal conductivity of a stress-relieving adhesive, such as that described in Embodiment 1, without the addition of fillers is about 0.2 W / k·m, but by adding silver powder as a filler, it was found that it could be improved to about 100 W / k·m.

[0104] The amount of these fillers added varies depending on their purpose, but they can achieve their purpose and exert their effectiveness by adding them in the range of 20 to 85 wt% for the matrix adhesive.

[0105] Furthermore, the thickness of the cured adhesive can be controlled by adjusting the size of the added filler. In this case, the maximum particle size can be added using materials that do not flatten during bonding.

[0106] Figure 9 This is a schematic diagram showing the structure of the stress-relieving adhesive 101 according to Embodiment 2. The stress-relieving adhesive 101 after adjustment and curing is as follows... Figure 9 As shown, the adhesive 1 has a structure in which a stress reliever 2 and a filler 3 are dispersed in an epoxy resin matrix. Here, the filler 3 added to the adhesive 1 can be surface-treated to improve the adhesion between the adhesive 1 and the filler 3. Specifically, silane coupling agents such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-ethoxypropylmethyldimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropyltriethoxysilane are used.

[0107] According to Embodiment 2, based on the same effects as Embodiment 1, by adding fillers to the stress-relieving adhesive, the viscosity can be adjusted. Furthermore, by adjusting the type and amount of the added fillers, the function can be improved accordingly to the purpose of the adhesive.

[0108] Furthermore, in the above embodiments, it is shown that the filler can be selected from glass, silicate minerals, engineered polymers, ceramics, silver, and carbon, but multiple selections are also possible. That is, at least one selected from glass, silicate minerals, engineered polymers, ceramics, silver, and carbon is sufficient.

[0109] Implementation method 3.

[0110] The rotary motor according to Embodiment 3 will now be described using the accompanying drawings. In the rotary motor according to Embodiment 3, a stress-relieving adhesive as described in Embodiments 1 or 2 is used for bonding the constituent components.

[0111] As an example of its application in rotating electric machines, in Figure 10A The image shows an IPM (Inter-Permanent Magnet) motor. Figure 10B The diagram shows an example of an SPM (Surface Permanent Magnet) motor. The figures are partial axial cross-sectional views, showing magnets 202 bonded to the rotor core 203, which serves as the rotation axis for shaft 204, using a stress-relieving adhesive 101. The magnets 202 used here can be any of the following: ferrite magnets, neodymium magnets, samarium cobalt magnets, alnico magnets, bonded magnets, or alloys thereof. The magnets 202 are bonded to the rotor core 203, but may be made of, for example, die-cast parts or electromagnetic steel sheets composed of layers of thin iron plates.

[0112] Figure 10A The IPM motor is configured such that magnet 202 is embedded in rotor core 203. Figure 10B The SPM motor is configured such that the magnet 202 is bonded to the rotor core 203. The required bonding strength, viscosity, etc. are different, but the stress-relieving adhesive 101 shown in Embodiment 1 or 2 above can be used for bonding.

[0113] As described above, when an electric motor in which the constituent components are bonded using stress-relieving adhesive 101 is used in an automobile, the bonding strength of the stress-relieving adhesive 101 does not decrease even in environments with significant temperature variations, such as the engine compartment, thus maintaining the reliability of the electric motor. Furthermore, the physical properties can be adjusted simply by modifying the added filler, therefore the same substance can be used for both the substrate adhesive and the substrate adhesive containing the stress-relieving agent.

[0114] Implementation method 4.

[0115] The electronic components involved in Embodiment 4 will now be described using the accompanying drawings.

[0116] The electronic components involved in Embodiment 4 require high heat resistance, and are therefore, for example, power devices that can handle large current flows of several hundred amperes. As described above, these electronic devices require heat resistance of around 200°C. Furthermore, power semiconductor devices made of wide-bandgap semiconductors such as SiC or GaN can operate at temperatures greater than or equal to 300°C; therefore, the module materials used to achieve this operational capability, such as connection materials and packaging materials, also require high heat resistance.

[0117] Figure 11 A cross-sectional structure of a semiconductor device is shown as an electronic component according to this embodiment. In this semiconductor device, a stress-relieving adhesive as described in Embodiment 1 or 2 above is used when bonding the constituent components.

[0118] In the figure, the semiconductor device has a semiconductor component 303 on a substrate 302. The electrodes (not shown) of the semiconductor component 303 and the electrodes (not shown) on the substrate 302 are connected by a wiring material 304, such as a wire. The semiconductor component 303 is encapsulated by an encapsulation material 305. The semiconductor component 303 is mounted on the substrate 302 by a stress-relieving adhesive 101.

[0119] Stress-relieving adhesive 101 is not limited to the above. Any amount of boron nitride, aluminum oxide, aluminum nitride, silver powder (in flake, spherical, needle-like and special shapes) can be added as needed to improve thermal conductivity.

[0120] In addition, the substrate 302 can be a printed wiring board made by laminating glass laminates using epoxy resin, a ceramic substrate made by laminating and sintering ceramic layers, or a lead frame made by stamping thin pure copper plates.

[0121] According to Embodiment 4, the electronic component has a member bonded by the stress-relieving adhesive described in Embodiments 1 or 2, thus exhibiting excellent heat resistance. Furthermore, when installed in a device equipped with the aforementioned electronic component, such as a power conversion device, for driving or controlling various automotive devices, the bonding strength of the stress-relieving adhesive 101 does not decrease even in environments with significant temperature variations, such as engine compartments, thus maintaining the reliability of the electronic component.

[0122] Implementation method 5.

[0123] The aircraft involved in Embodiment 5 will now be described using the accompanying drawings.

[0124] Figure 12 This is a block diagram illustrating the airflow related to the in-flight air conditioning of the aircraft according to Embodiment 5. A typical jet engine 401 is configured to introduce external gas, generate compressed air via a compressor, and intermittently burn it with fuel in the combustion chamber. The air exhausted from the combustion chamber is cooled to an arbitrary temperature by passing through heat exchangers 402 in each unit. Alternatively, a portion of the compressed air generated by the compressor 403 is introduced and sent to the aircraft's air conditioning system, where it is cooled and ventilated to the cabin. Additionally, air is directly introduced from external gas via heat exchangers 404 to the compressor 403.

[0125] Here, the external air temperature outside the aircraft is 0–40°C at ground level and -40–0°C at altitudes greater than or equal to 10,000 meters. Therefore, the components and sensors mounted in the heat exchangers 402, 404, and compressor 403 are designed to be exposed to temperatures ranging from 100–200°C to -40°C caused by the operation of the engine 401. Here, heat exchanger 402, located near the heat source close to the engine, requires a heat resistance of approximately 200°C. Heat exchangers 404 and compressor 403 operate at temperatures lower than 200°C, but are required to be usable at both high and low temperatures. The adhesive described in Embodiment 1 or 2 has high-temperature heat resistance and can be used for bonding sensor components mounted in heat exchangers 404 and compressor 403 in applications such as heat exchanger 402 and at temperatures around -10°C to 130°C.

[0126] As described above, in the aircraft according to Embodiment 5, the components constituting devices such as heat exchangers and compressors, as well as sensors, are bonded using the stress-relieving adhesive 101 described in Embodiments 1 or 2. Therefore, it not only has high heat resistance but also maintains bonding strength in environments ranging from -40°C to 200°C. Thus, it is possible to realize an aircraft equipped with a device having highly reliable adhesive joints between components.

[0127] Other implementation methods.

[0128] (1) Stress Relief Agent

[0129] In embodiments 1 to 5 described above, one type of stress reliever is shown. However, when the stress reliever is an ethylene-acrylic acid copolymer, at least one of the following can be selected: ethylene dimethacrylate, hexamethylene diacrylate, tetramethylene dimethyl methacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, and 1,3-butanediol diacrylate.

[0130] In addition, when the stress reliever is an ethylene-propylene copolymer, it is acceptable to select at least one of propylene glycol diacrylate, tripropylene glycol diacrylate, 2-hydroxypropyl methacrylate, dipropylene glycol diacrylate, and tripropylene acrylate.

[0131] As a stress reliever, multiple options can be selected from the aforementioned ethylene-acrylic acid copolymer and ethylene-propylene copolymer.

[0132] (2) Surface treatment

[0133] Furthermore, while the surface treatment of the test piece in Embodiment 1 has been described, when bonding the structural components shown in Embodiments 3 to 5, surface treatment can improve the bonding strength. Specifically, physical treatments such as atmospheric plasma treatment, deep ultraviolet light treatment, corona discharge treatment, and roughening treatment (laser roughening, grinding, sandblasting) can be performed as pretreatment. Alternatively, the same effect can be obtained by applying a silane coupling agent as a primer as a chemical treatment. For example, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldioxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride can be used as primers for epoxy resin adhesives.

[0134] This invention describes various exemplary embodiments and examples, but the various features, methods and functions described in one or more embodiments are not limited to the application of a specific embodiment, and can also be applied to the embodiment alone or in various combinations.

[0135] Therefore, numerous variations not illustrated within the scope of the technology disclosed in this application are envisioned. These include variations of at least one structural element, additions, omissions, and combinations of at least one structural element with structural elements from other embodiments.

[0136] Explanation of the label

[0137] 1: Epoxy resin adhesive (matrix adhesive), 2: Stress reliever, 3: Filler, 101: Stress-relieving adhesive, 102: SPCC board, 103: Coagulation failure mode, 104: Interface peeling mode, 202: Magnet, 203: Rotor core, 204: Shaft, 302: Substrate, 303: Semiconductor component, 304: Wiring material, 305: Encapsulation material, 401: Engine, 402, 404: Heat exchanger, 403: Compressor.

Claims

1. An adhesive, An epoxy resin compound with an allyl group having two or more functional groups is used as the main agent. Epoxy resin-based matrix adhesives are constructed using amine curing agents with a bisphenol A-type resin backbone. As a stress reliever, at least one of ethylene-acrylic acid copolymer and ethylene-propylene copolymer with an average particle diameter of less than or equal to 10 μm is contained in a range of less than or equal to 20 wt% relative to the matrix adhesive.

2. The adhesive according to claim 1, wherein, When the stress reliever is an ethylene-acrylic acid copolymer, it is at least one selected from diethylene methacrylate, hexamethylene diacrylate, tetramethylene dimethyl methacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, and 1,3-butanediol diacrylate. In the case where the stress reliever is an ethylene-propylene copolymer, it is selected from at least one of propylene glycol diacrylate, tripropylene glycol diacrylate, 2-hydroxypropyl methacrylate, dipropylene glycol diacrylate and tripropylene acrylate.

3. The adhesive according to claim 1 or 2, wherein, The filler is contained in a proportion of greater than or equal to 20 wt% and less than or equal to 85 wt% relative to the matrix adhesive.

4. The adhesive according to claim 3, wherein, The filler is selected from at least one of glass, silicate minerals, engineered polymers, ceramics, silver, and carbon.

5. A rotary electric motor having constituent components bonded by an adhesive as described in any one of claims 1 to 4.

6. An electronic component having constituent members bonded by an adhesive as described in any one of claims 1 to 4.

7. An aircraft having constituent parts bonded by an adhesive as described in any one of claims 1 to 4.

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