Thermal interface material and on-vehicle electronic control unit using said thermal interface material

Abstract

Provided are: a thermal interface material which has a thermal conductivity of 8 W / (m·K) or more and in which generation of undesired cracks / voids is suppressed even after undergoing a prescribed temperature cycle test; and an on-vehicle ECU using said thermal interface material. An on-vehicle electronic control unit according to the present invention is characterized in that: a prescribed thermal interface material is interposed between an electronic component and a heat dissipation member; the thermal interface material is obtained by dispersing particles of a thermally conductive filler in a matrix of a resin material; the thermally conductive filler is aluminum nitride and is contained in an amount of 92 mass% or more in the thermal interface material; the resin material is a silicone resin; and the molar concentration of vinyl group structures included in the resin material, when being quantitatively analyzed by a nuclear magnetic resonance device, is 1.7 mol% or less.

Description

Thermal interface material and on-board electronic control device using said thermal interface material

[0001] The present invention relates to a thermal interface material to be interposed between an electronic component and a heat dissipation member, and to an on-vehicle electronic control unit using the thermal interface material.

[0002] The technologies of advanced driver assistance systems (ADAS) and autonomous driving (AD) for automobiles and other vehicles have made great progress in recent years, and further development is expected in the future. In ADAS and AD, electronic control units (ECUs) play a very important role, and many ECUs are installed for various applications and purposes. In this specification, the various ECUs installed in automobiles and other vehicles are collectively referred to as automotive ECUs.

[0003] In-vehicle ECUs perform complex and advanced calculations, and generate a lot of heat from electronic components such as integrated circuits (ICs), so they require heat dissipation using heat dissipation materials such as heat sinks and heat spreaders to prevent thermal runaway.In such cases, thermal interface materials (TIMs, also known as heat dissipation materials or thermal conductive materials) are often placed between the electronic components and the heat dissipation materials to improve heat dissipation efficiency.

[0004] For example, Patent Document 1 (JP 2021-152101 A) teaches an insulating film comprising a resin and an inorganic filler dispersed in the resin, wherein the resin has a viscosity of 50 MPa·s or less at 200°C, the inorganic filler has an average particle diameter in the range of 0.1 μm or more and 20 μm or less, and the content of the inorganic filler in the insulating film is in the range of 50 vol% or more and 85 vol% or less.

[0005] Patent Document 1 teaches that the resin is preferably a polyimide resin, a polyamide-imide resin, or a mixture thereof, and that the inorganic filler may be alumina (Al2O3) particles, alumina hydrate particles, aluminum nitride (AlN) particles, silica (SiO2) particles, silicon carbide (SiC) particles, titanium oxide (TiO2) particles, boron nitride (BN) particles, or the like, with alumina particles being preferred among these.

[0006] According to Patent Document 1, it is possible to provide an insulating film that is easy to reduce voids and has excellent thermal conductivity and voltage resistance.

[0007] Japanese Patent Application Laid-Open No. 2021-152101

[0008] ADAS and AD technologies are expected to continue to develop in the future, which is expected to lead to an increase in the amount of heat generated by ECUs, making the TIM, which affects heat dissipation, increasingly important.

[0009] The thermal conductivity of TIM currently in practical use is said to be limited to around 5 W / (m・K). However, considering the future increase in heat generation by ECUs, it is said that the thermal conductivity of TIM needs to be at least 8 W / (m・K), with 10 W / (m・K) or more being more desirable.

[0010] One possible way to increase the thermal conductivity of TIM is to mix a high-thermal-conductivity filler in at a high ratio. From this perspective, AlN material, which has high thermal conductivity (thermal conductivity ≒ 155 W / (m・K)), is a promising candidate for the filler to be mixed into TIM.

[0011] On the other hand, when considering an in-vehicle ECU, TIM is required to withstand the temperature environment in which the vehicle is used without significant deterioration in performance even after undergoing temperature cycle testing (for example, -40°C ⇔ 105°C, 1000 cycles).

[0012] However, according to the research of the present inventors, when the thermally conductive filler in a conventional TIM (for example, an Al2O3 material (thermal conductivity ≈ 30 W / (m·K))) is simply replaced with an AlN material, it is possible to improve the initial thermal conductivity performance, but it has been found that a temperature cycle test causes the matrix resin and the filler to peel off, causing undesired cracks / voids in the TIM, resulting in a significant decrease / deterioration of the thermal conductivity of the TIM (details will be described later).

[0013] The present invention was made based on the above-mentioned technical background, and an object of the present invention is to provide a thermal interface material that has a thermal conductivity of 8 W / (m·K) or more and that suppresses the occurrence of undesired cracks / voids even after undergoing a specified temperature cycle test, and an on-vehicle ECU that uses the thermal interface material.

[0014] (I) One aspect of the present invention is an in-vehicle electronic control device having a predetermined thermal interface material interposed between an electronic component and a heat dissipation member, wherein the thermal interface material is a resin material matrix having thermally conductive filler particles dispersed therein, the thermally conductive filler being aluminum nitride and being contained in the thermal interface material at a content of 92 mass% or more, and the resin material being a silicone resin, wherein the molar concentration of vinyl group structures [-Si-CH=CH2] contained in the resin material is 1.7 mol% or less when quantitatively analyzed by a nuclear magnetic resonance (NMR) spectrometer.

[0015] (II) Another aspect of the present invention is a thermal interface material in which thermally conductive filler particles are dispersed in a matrix of a resin material, wherein the thermally conductive filler is aluminum nitride and is contained in the thermal interface material in an amount of 92 mass% or more, and the resin material is a silicone resin, and when the molar concentration of vinyl group structures contained in the resin material is quantitatively analyzed by a nuclear magnetic resonance spectrometer, the molar concentration is 1.7 mol% or less.

[0016] The present invention allows the following improvements and modifications to be freely combined in the on-board electronic control device (I) and thermal interface material (II) according to the present invention. (i) When the void fraction of the thermal interface material is measured using a transparent X-ray inspection device after a predetermined temperature cycle test, the void fraction is 6 area % or less. (ii) The thermal interface material has a thermal conductivity of 8 W / (m·K) or more. (iii) The thermal interface material has a Shore hardness of 50 to 90 Shore OO (double O). (iv) The thermal interface material has a tensile shear bond strength of 0.03 MPa or more.

[0017] Furthermore, the present invention allows the following improvements and modifications to be freely combined in the on-vehicle electronic control device (I) according to the present invention: (v) the heat dissipation member is the housing of the on-vehicle electronic control device; (vi) the thermal interface material is disposed so as to abut against a heat dissipation base formed on the heat dissipation member and the electronic component.

[0018] According to the present invention, it is possible to provide a thermal interface material that has a thermal conductivity of 8 W / (m·K) or more and that suppresses the occurrence of unwanted cracks / voids even after undergoing a predetermined temperature cycle test, and an on-vehicle ECU that uses the thermal interface material. Note that other issues, configurations, and effects will become clear from the description of the embodiments described below.

[0019] 1A is an exploded perspective schematic view showing an example of an in-vehicle ECU according to the present invention. 1B is an exploded perspective schematic view showing the exploded perspective view shown in FIG. 1A from the opposite top and bottom sides. 1C is a partial cross-sectional schematic view of the in-vehicle ECU shown in FIG. 1B. 1D is a fluoroscopic X-ray observation image of Comparative Example 1. 1E is a fluoroscopic X-ray observation image of Example 1. 1F is a graph showing the relationship between the molar concentration of residual vinyl group structures and the void fraction in Comparative Examples 1 to 3 and Examples 1 to 4.

[0020] [Preliminary Study and Basic Concept of the Present Invention] The present inventors investigated a method of incorporating a high thermal conductive filler at a high blending ratio as a means of increasing the thermal conductivity of a TIM. As mentioned above, Patent Document 1 states that Al2O3 particles, AlN particles, SiO2 particles, SiC particles, TiO2 particles, BN particles, etc. can be used as the inorganic filler.

[0021] Here, it was thought that it would be difficult to achieve a thermal conductivity of 8 W / (m・K) or more in a TIM using fillers such as Al2O3 (thermal conductivity ≒ 30 W / (m・K)), TiO2 (thermal conductivity ≒ 10 W / (m・K)), or SiO2 (thermal conductivity ≒ 1.4 W / (m・K)), even when mixed at a high blend ratio. From the perspective of TIM thermal conductivity, fillers such as BN (thermal conductivity ≒ 60 W / (m・K)), AlN (thermal conductivity ≒ 155 W / (m・K)), SiC (thermal conductivity ≒ 160 W / (m・K)), and graphite (bulk thermal conductivity ≒ 200 W / (m・K)) are candidates.

[0022] On the other hand, when applying a TIM to an electronic component such as an IC, there is a possibility that the TIM may come into contact with the lead wires of the electronic component. To prevent unwanted leakage current in electronic components, it is desirable for the TIM to exhibit electrical insulation. From this perspective, SiC materials are semiconductive, while graphite materials are conductive, which makes them unsuitable for ensuring the electrical insulation of the TIM. For these reasons, AlN materials, which combine high thermal conductivity and electrical insulation, are a promising candidate for the filler.

[0023] Furthermore, when considering an in-vehicle ECU, TIM is required to have its performance maintained even after undergoing temperature cycle testing (for example, -40°C ⇔ 105°C, 1000 cycles) so that it can withstand the temperature environment in which the vehicle is used.

[0024] The inventors investigated the relationship between the filler content and the thermal conductivity of a conventional TIM consisting of a silicone resin matrix and Al2O3 particles as a filler, but simply replacing the filler with AlN particles. The thermal conductivity of the TIM immediately after fabrication and after a temperature cycle test (-40°C ⇔ 105°C, 1000 cycles) were investigated. The results are shown in Table 1.

[0025]

[0026] As shown in Table 1, the thermal conductivity of the TIM immediately after fabrication increased with increasing AlN filler content, achieving a thermal conductivity of 8 W / (m K) at an AlN filler content of 92 mass%. However, it was found that the thermal conductivity of the TIM after the temperature cycle test remained unchanged at AlN filler content of 90 mass% or less, but dropped significantly to less than 8 W / (m K) at AlN filler content of 92 mass% or more.

[0027] To investigate the cause of the decrease in thermal conductivity of the TIM, a transmission X-ray inspection device was used to examine the TIM samples after the temperature cycle test. It was confirmed that clear cracks / voids had occurred within the TIM in samples with an AlN filler content of 92% by mass or more. On the other hand, in samples with an AlN filler content of 90% by mass or less, although it cannot be said that there were no voids, no clear cracks were confirmed within the TIM. Based on these findings, it is believed that the decrease in thermal conductivity in samples with an AlN filler content of 92% by mass or more was due to cracks occurring within the TIM during the temperature cycle test, which resulted in the formation of large voids.

[0028] To investigate the cause of cracks / voids occurring in TIM due to the high AlN filler content, a TIM sample with an Al2O3 filler content of 92 mass% was prepared and cracks / voids in the TIM after a temperature cycle test were examined using a transmission X-ray inspection device. As a result, no clear cracks were confirmed in the TIM sample with an Al2O3 filler content of 92 mass%.

[0029] The inventors investigated and considered the differences between conventional TIM containing Al2O3 filler and TIM containing AlN filler, and concluded that Al2O3 filler has a high bonding ability with silane coupling agents, which is thought to enhance the bonding between the TIM matrix resin and Al2O3 filler via the silane coupling agent.

[0030] In contrast, AlN filler has low bonding strength with silane coupling agents, and it was thought that even with the silane coupling agent, the bonding strength between the TIM matrix resin and AlN filler would not be strong.As a result, repeated thermal expansion and contraction due to temperature cycling caused delamination between the TIM matrix resin and AlN filler, resulting in cracks, which in turn caused the formation of large voids.

[0031] The present inventors focused on the vinyl group structure in cured silicone resins when silicone resins were used as the matrix material for TIMs, and conducted extensive research and studies to determine the relationship between the amount of vinyl group structure remaining and the amount of voids formed. As a result, they discovered that by controlling the molar concentration of vinyl group structures [-Si-CH=CH2] in the cured silicone resin to a predetermined value or less, the occurrence of undesired cracks / voids can be suppressed even after a predetermined temperature cycle test, and a TIM with a thermal conductivity of 8 W / (m·K) or more can be obtained. The present invention was completed based on this finding.

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, for mechanisms and configurations that have the same meaning (including cases where the differences are small), the same reference numerals will be used and duplicate descriptions will be omitted. Furthermore, the present invention is not limited to the embodiments described herein, and can be appropriately combined with known technologies or improved based on known technologies within the scope of the technical concept of the invention.

[0033] [On-vehicle electronic control device] FIG. 1A is an exploded perspective schematic view showing an example of an on-vehicle ECU according to the present invention, FIG. 1B is an exploded perspective schematic view showing the exploded perspective view shown in FIG. 1A from the opposite top and bottom sides, and FIG. 1C is a partial cross-sectional schematic view of the on-vehicle ECU shown in FIG. 1B.

[0034] As described above, an in-vehicle ECU is a type of computer that electronically controls various applications / purposes (e.g., engine, transmission, steering, airbags, etc.) in driving an automobile or the like, and has an internal electronic circuit. As shown in Figures 1A to 1C, an in-vehicle ECU 100 is an example in which the cover 40, of the cover 40, base 50, and fasteners 60 that constitute a housing, also serves as a heat dissipation member. An electronic circuit is formed by mounting (electrically connecting) electronic components 10 and connectors 20 on a circuit board 30, and these are housed in the housing (cover 40, base 50) with a TIM 15 interposed between the electronic components 10 and the cover 40.

[0035] Each part will now be described in more detail.

[0036] The electronic component 10 is not particularly limited as long as it is for automotive use, and may be, for example, a semiconductor element such as a central processing unit (CPU), a graphics processing unit (GPU), a system on a chip (SoC), or a double-data-rate synchronous dynamic random access memory (DDR SDRAM). In FIG. 1C , the electronic component 10 is depicted as a ball grid array (BGA) package in which an IC chip 11 is connected to an interposer 12 and connected to a circuit board 30 via bumps 13. Naturally, the electronic component 10 is not limited to a BGA package, and a lead frame type package may also be used.

[0037] The connector 20 is a part that electrically connects the electronic component 10 mounted on the circuit board 30 to an external device. There are no particular limitations on the connector 20, and a conventional connector for use in a vehicle can be used as appropriate.

[0038] The circuit board 30 is a substrate in which metal wiring is formed on an electrically insulating base material, and a conventional in-vehicle circuit board can be used as appropriate, similar to the electronic components 10 and connectors 20. In the example shown in Figures 1A and 1B, fixing holes are provided in the outer peripheral region, and the circuit board is configured to be fixed to the cover 40 by fasteners 60 (e.g., fixing screws).

[0039] The cover 40 and base 50 are combined with fasteners 60 to form a waterproof and dustproof sealed housing. In the example shown in Figures 1A to 1C, the cover 40 also functions as a heat dissipation member, as described above. The TIM 15 is disposed so as to be sandwiched and in contact between the cover 40 and the electronic component 10, and is capable of efficiently transferring heat from the electronic component 10 to the cover 40. Details of the TIM 15 will be described later.

[0040] The heat dissipation pedestal 45 formed on the cover 40 is not an essential component of the present invention, but is preferably formed from the viewpoints of heat dissipation efficiency and assembly efficiency. 1A and 1B show an example in which two heat dissipation pedestals 45 are formed to respectively correspond to two electronic components 10, but a configuration in which one heat dissipation pedestal 45 corresponds to two electronic components 10 may also be used.

[0041] There are no particular limitations on the materials for the cover 40 and the base 50 as long as they have the heat resistance, waterproofness, dustproofness, and thermal conductivity required for in-vehicle use, and metal materials (e.g., aluminum alloys, magnesium alloys, steel materials) or highly thermally conductive resin materials (e.g., polybutylene terephthalate resin (PBT), polyphenylene sulfide resin (PPS), or polyamide resin (PA6) containing thermally conductive fillers) can be used as appropriate. The heat dissipation member is not limited to the cover 40; the base 50 may also function as a heat dissipation member, or both the cover 40 and the base 50 may also function as heat dissipation members.

[0042] In addition to its function as a thermally conductive material, TIM 15 is also required to function as an adhesive / pressure-sensitive adhesive. Before curing, it is preferable for the material to have fluidity from the viewpoint of workability, with a viscosity of, for example, 100 Pa·s or more and 600 Pa·s or less. On the other hand, after curing, it is preferable for the material not to cause displacement or flow due to vibrations or stresses during vehicle operation, with a Shore OO (double-O) hardness of, for example, 50 to 90 and / or a tensile shear bond strength of 0.03 MPa or more. More specifically, it is preferable to use a material with a silicone resin matrix as TIM 15, and a two-component addition reaction type silicone resin is particularly preferable.

[0043] The silicone resin may be thermosetting or room temperature curable, but from the viewpoint of environmental load (for example, carbon neutrality), room temperature curable is more preferable.

[0044] Silicone resin is a synthetic polymer material with a main skeleton made of siloxane bonds (Si-O-Si bonds). Silicone resin has excellent heat resistance (over 200°C) and chemical stability, and its elastic properties also give it the advantage of being able to absorb and mitigate vibration and impact. Two-part mixed addition reaction silicone resin cures through an addition reaction between the vinyl group "-Si-CH=CH2" of the main component and the -Si-H group of the curing agent in a catalytic environment (usually a platinum catalyst).

[0045] Cured silicone resins contain the following chemical structures: the main backbone structure (-O-Si-(CH3)2-), the main chain structure (-Si-CH2CH2-Si-), and the vinyl group structure (-Si-CH=CH2). The inventors conducted extensive research into the relationship between the remaining vinyl group structure (-Si-CH=CH2), which is known to indicate the degree of crosslinking, and the cracks and voids that occur within TIM 15. As a result, they discovered that controlling the molar concentration of the remaining vinyl group structure to a predetermined value or below can suppress the occurrence of unwanted cracks and the resulting void formation. The molar concentration of each chemical structure can be measured by quantitative analysis using a nuclear magnetic resonance (NMR) spectrometer.

[0046] Furthermore, when the amount of cracks / voids (hereinafter collectively referred to as the void fraction) generated in TIM 15 is measured within the plane of TIM 15 (transmission in the thickness direction of TIM 15) using a transmission-type X-ray inspection device, it was found that if the void fraction is 6 area % or less, there is no significant change in the thermal conductivity of TIM 15 before and after a specified temperature cycle test (-40°C⇔105°C, 1000 cycles). The void fraction is more preferably 5 area % or less, and even more preferably 4 area % or less.

[0047] An investigation into the relationship between the molar concentration of vinyl group structures [-Si-CH=CH2] in cured silicone resin and the void fraction within the TIM revealed that a void fraction of 6 area percent or less can be achieved by controlling the concentration to 1.7 mol% or less. A molar concentration of vinyl group structures in cured silicone resin of 1.1 mol% or less is more preferable, and a molar concentration of 0.6 mol% or less is even more preferable.

[0048] There are no particular limitations on the method for controlling the molar concentration of the vinyl group structure remaining in the cured silicone resin, but examples include controlling the molar concentration of the main chain structure "-Si-CH2CH2-Si-" and the vinyl group "-Si-CH=CH2" in the base resin before mixing, controlling the mixing ratio of the curing agent, or controlling the amount and chemical activity of the platinum catalyst.

[0049] To increase the adhesive strength and holding power of the TIM, it is preferable that the Shore OO (double O) hardness of the cured silicone resin is 50 or more and 90 or less. A Shore hardness that is too high will result in reduced vibration and stress absorption and relaxation. A Shore hardness that is too low will not ensure sufficient holding power. Furthermore, from the viewpoint of preventing misalignment, the adhesive strength of the TIM after curing is preferably a tensile shear bond strength of 0.03 MPa or more, and more preferably a tensile shear bond strength of 0.04 MPa or more.

[0050] The present invention will be explained in more detail below with reference to various experiments, but the present invention is not limited to the configurations and structures described in these experiments.

[0051] [Experiment 1] (Preparation of silicone resins A to E that make up the TIM) A commercially available two-part addition reaction type room-temperature curing silicone resin was prepared as the resin material that makes up the TIM. By controlling the molar concentrations of the main chain structure "-Si-CH2CH2-Si-" and vinyl group "-Si-CH=CH2" in the base resin before mixing, and by controlling the mixing ratio of the curing agent, two-part addition reaction type room-temperature curing silicone resins A to F were prepared, each with a different molar concentration of vinyl group structure remaining in the silicone resin after curing.

[0052] [Experiment 2] (Measurement of the molar concentration of vinyl group structures remaining in cured silicone resins) For cured silicone resins A to F, a quantitative analysis of the molar concentration of vinyl group structures [—Si—CH═CH2] remaining in the resin was performed. Using an NMR device (JEOL Ltd., Model: ECA-500FT-NMR) under specified measurement conditions (measurement nuclide: 1H, magnetic field strength: 11.7 T (500 MHz for 1H nuclei), observation frequency range: -2.5 ppm to 12.5 ppm (45° pulse), number of data points: 16,384 points, measurement mode: 13C decoupling, repetition time: 30 s, number of accumulations: 256, measurement solvent: deuterated chloroform, measurement temperature: room temperature), the molar concentration of vinyl group structures [—Si—CH═CH2] was measured. The results are shown in Table 2 below.

[0053] [Experiment 3] (Preparation of TIMs for Comparative Examples 1 to 3 and Examples 1 to 4) Commercially available AlN powder (Tokuyama Corporation, average particle size D50 = 120 μm) was prepared as the thermally conductive filler for the TIM. A TIM precursor was prepared by thoroughly mixing 95 to 96 mass% of AlN powder with uncured silicone resins A to F. Next, each TIM precursor was poured into a mold with a diameter of 50 mm and a depth of 1 mm and cured under appropriate conditions to prepare the TIM samples for Comparative Examples 1 to 3 and Examples 1 to 4.

[0054] [Experiment 4] (Investigation of TIM Properties) Each TIM sample (Comparative Examples 1-3 and Examples 1-4) prepared in Experiment 3 was subjected to a Shore hardness test in accordance with ASTM D2240 to measure Shore OO (double-O) hardness. Tensile shear bond strength was also measured in accordance with JIS K6850. Using a precision universal testing machine (Shimadzu Corporation, Model: AGS-H 500N), the maximum load was measured at a tensile speed of 5 mm / min, and the tensile shear bond strength was calculated by dividing the load by the shear area. The results of Shore OO hardness and tensile shear bond strength are shown in Table 2.

[0055] [Experiment 5] (Measurement of Void Fraction in TIM After Temperature Cycle Test) To simulate an automotive ECU, pseudo-circuit boards (PSBs) were fabricated using the TIM samples (Comparative Examples 1-3 and Examples 1-4) fabricated in Experiment 3 and placed on electronic components. A temperature cycle test (-40°C ⇔ 105°C, 1000 cycles) was performed on the fabricated PSBs. Next, the void fraction in the TIM was measured for each PSB that underwent the temperature cycle test using a fluoroscopic X-ray inspection system (Shimadzu Corporation, Model: Xslicer SMX-1010). The measurement conditions were: spatial resolution: equivalent to 5 μm on a JIMA RT RC-05 microchart; X-ray output: maximum tube voltage: 90 kV; maximum tube current: 250 μA. The results are shown in Table 2.

[0056]

[0057] Fig. 2A is a fluoroscopic X-ray image of Comparative Example 1, and Fig. 2B is a fluoroscopic X-ray image of Example 1. Fig. 3 is a graph showing the relationship between the molar concentration of the residual vinyl group structure and the void fraction in Comparative Examples 1 to 3 and Examples 1 to 4.

[0058] As shown in Table 2, lowering the molar concentration of vinyl group structures remaining in the cured silicone resin reduces the void fraction in the TIM after the temperature cycle test. As is clear from Figures 2A and 2B, in Comparative Example 1, which has a high molar concentration of residual vinyl group structures, cracks occur in the TIM after the temperature cycle test, resulting in the formation of large voids. However, in Example 1, which has a low molar concentration of residual vinyl group structures, no cracks occur in the TIM even after the temperature cycle test, and only small voids are observed. Furthermore, as shown in Figure 3, it can be seen that in order to achieve a void fraction of 6 area percent or less after the temperature cycle test, it is necessary to control the molar concentration of residual vinyl group structures to 1.7 mol% or less.

[0059] [Experiment 6] (Measurement of Thermal Conductivity of TIM After Temperature Cycle Test) The TIM samples of Examples 1 to 4 prepared in Experiment 3 were subjected to a temperature cycle test (-40°C ⇔ 105°C, 1000 cycles). Next, the specific heat of the TIM samples subjected to the temperature cycle test was measured using a differential scanning calorimeter (TA Instruments Japan, Model: DSC 2000), the density was measured using an electronic hydrometer (Alpha Mirage, Model: EW-300G), and the thermal diffusivity was measured using a thermal diffusivity measurement device (iPhase, Model: Mobile Q3). The thermal conductivity at room temperature was calculated from the measured specific heat, density, and thermal diffusivity. As a result, it was confirmed that all of the TIM samples of Examples 1 to 4 achieved a thermal conductivity of 8 W / (m·K) or higher.

[0060] The above-described embodiments and experiments have been described to aid in understanding the present invention, and the present invention is not limited to the specific configurations described. For example, it is possible to replace part of the configuration of the embodiments with configurations that are within the technical common sense of those skilled in the art, and it is also possible to add configurations that are within the technical common sense of those skilled in the art to the configuration of the embodiments. That is, it is possible to delete, replace, or add part of the configurations of the embodiments and experiments described in this specification to the extent that they do not deviate from the technical concept of the invention. For example, the heat dissipation material used in the present invention is not limited to use in automotive ECUs, but can also be used as a heat dissipation material for inverters, converters, and other devices other than those on automotive systems.

[0061] 100...In-vehicle electronic control device, 10...Electronic component, 11...Chip, 12...Interposer, 13...Bump, 15...Heat dissipation material, 20...Connector, 30...Circuit board, 40...Cover, 45...Heat dissipation base, 50...Base, 60...Fastener

Claims

1. An on-vehicle electronic control device having a predetermined thermal interface material interposed between an electronic component and a heat dissipation member, wherein the thermal interface material is a resin material matrix having thermally conductive filler particles dispersed therein, the thermally conductive filler is aluminum nitride and is contained in the thermal interface material at a concentration of 92 mass% or more, and the resin material is a silicone resin, and when the molar concentration of vinyl group structures contained in the resin material is quantitatively analyzed using a nuclear magnetic resonance spectrometer, the molar concentration is 1.7 mol% or less.

2. An on-vehicle electronic control device according to claim 1, wherein when the void ratio of the thermal interface material is measured using a transparent X-ray inspection device after the thermal interface material has been subjected to a predetermined temperature cycle test, the void ratio is 6% by area or less.

3. An on-vehicle electronic control device according to claim 1, wherein the thermal interface material has a thermal conductivity of 8 W / (m·K) or more.

4. An on-vehicle electronic control device according to claim 2, wherein the thermal interface material has a thermal conductivity of 8 W / (m·K) or more.

5. An on-vehicle electronic control device according to any one of claims 1 to 4, wherein the thermal interface material has a Shore hardness of 50 or more and 90 or less in Shore OO.

6. An on-vehicle electronic control device according to any one of claims 1 to 5, wherein the thermal interface material has a tensile shear adhesive strength of 0.03 MPa or more.

7. An on-vehicle electronic control device according to any one of claims 1 to 6, wherein the heat dissipation member is a housing of the on-vehicle electronic control device.

8. An on-vehicle electronic control device according to claim 7, characterized in that the thermal interface material is arranged so as to abut against a heat dissipation base formed on the heat dissipation member and the electronic component.

9. A thermal interface material comprising a resin material matrix having thermally conductive filler particles dispersed therein, wherein the thermally conductive filler is aluminum nitride and is contained in the thermal interface material at a content of 92 mass% or more, and the resin material is a silicone resin, and when the molar concentration of vinyl group structures contained in the resin material is quantitatively analyzed using a nuclear magnetic resonance spectrometer, the molar concentration is 1.7 mol% or less.

10. The thermal interface material according to claim 9, wherein when the void fraction of the thermal interface material is measured using a transparent X-ray inspection device after a predetermined temperature cycle test, the void fraction is 6% by area or less.

11. The thermal interface material of claim 9, wherein the thermal interface material has a thermal conductivity of 8 W / (m·K) or greater.

12. The thermal interface material of claim 10, wherein the thermal interface material has a thermal conductivity of 8 W / (m·K) or greater.

13. The thermal interface material according to any one of claims 9 to 12, characterized in that the thermal interface material has a Shore hardness of 50 or more and 90 or less, Shore OO.

14. The thermal interface material according to any one of claims 9 to 13, characterized in that the thermal interface material has a tensile shear bond strength of 0.03 MPa or greater.

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