Bonding material for heat dissipation substrate, method for manufacturing heat dissipation substrate, and heat dissipation substrate

Abstract

To provide a bonding material for a heat dissipation substrate that enables the manufacture of high-performance heat dissipation substrates through low-temperature, short-time heat treatment.SOLUTION: In a heat dissipation substrate 1, a bonding material for a heat dissipation substrate includes a thermoplastic resin having a glass transition point of 200°C or higher and 300°C or lower, and a thermally conductive material containing at least first particles having a D50 particle diameter of 2 μm or higher and 5 μm or lower and an average aspect ratio of 1.2 or higher. In this bonding material, the content of the first particles is 70 wt% or higher and 100 wt% or lower, when the total mass of the thermally conductive material is 100 wt%. With this bonding material, a bonding layer 40 with excellent bonding strength, heat resistance, and thermal conductivity can be formed at the interfaces between a circuit member 20 and a ceramic member 10 and between a heat dissipation member 30 and the ceramic member 10 by low-temperature, short-time heat treatment.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed herein relates to a bonding material for a heat dissipation substrate, a method for manufacturing a heat dissipation substrate, and a heat dissipation substrate. [Background technology]

[0002] In recent years, there has been an increasing demand for even higher performance in power devices. To meet these demands, semiconductors with high heat generation, such as SiC power semiconductors, are increasingly being used. When using semiconductors with high heat generation, heat countermeasures are important, and substrates with high heat dissipation properties are sometimes used. These heat dissipation substrates have a laminated structure in which, for example, metal heat dissipation members and ceramic members are stacked. In these heat dissipation substrates, heat generated on the circuit side is transferred to the heat dissipation member side via the ceramic members. This suppresses the temperature rise on the circuit side. Furthermore, a bonding material for heat dissipation substrates (hereinafter simply referred to as "bonding material") is used to bond the various components that make up the heat dissipation substrate. Bonding strength, heat resistance, and thermal conductivity are required for these bonding materials.

[0003] An example of a bonding material for a heat dissipation substrate is a brazing filler metal. The brazing filler metal is a paste containing metal powder and organic components (binder resin, organic solvent, etc.). In manufacturing a heat dissipation substrate, the brazing filler metal is applied between two components to be joined. When this laminate is then fired at a high temperature, the organic components in the brazing filler metal are burned away and the metal powder is melted. The molten metal then solidifies, joining the components to be joined. Patent Document 1 discloses an example of a brazing filler metal. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5605423 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional manufacturing methods require high-temperature firing to fully melt the metal powder in the brazing filler metal. For example, when using a brazing filler metal containing silver (Ag) and copper (Cu) as the metal powder, firing at 700°C or higher is required. Furthermore, because firing is typically performed in a batch furnace, it requires a long processing time of 10 hours or more. In response to this, there is a growing demand for bonding materials that can be used to manufacture high-performance heat dissipation substrates with low-temperature, short-time heating, in consideration of environmental impact and manufacturing costs.

[0006] The technology disclosed herein has been made to solve such problems, and aims to provide a bonding material for heat dissipation substrates that can produce high-performance heat dissipation substrates through low-temperature, short-time heat treatment. [Means for solving the problem]

[0007] To address the above-mentioned problems, a bonding material for a heat dissipation substrate having the following configuration is provided.

[0008] The adhesive for a heat dissipation substrate disclosed herein is used for bonding components of a heat dissipation substrate. This adhesive comprises a thermoplastic resin having a glass transition temperature of 200°C or more and 300°C or less, and a D 50 and a thermally conductive material containing at least first particles having a particle diameter of 2 μm or more and 5 μm or less and an average aspect ratio of 3 or more. In the bonding material disclosed herein, when the total mass of the thermally conductive material is taken as 100 wt%, the content of the first particles is 70 wt% or more and 100 wt% or less.

[0009] After extensive research into new bonding materials to replace brazing materials, the inventors came up with the idea of ​​using a thermoplastic resin as a bonding material for heat dissipation substrates. This thermoplastic resin softens when heated to a temperature above its glass transition point. When the objects to be bonded are clamped and cooled in this state, the thermoplastic resin hardens, allowing the objects to be bonded. By adopting a bonding method using this thermoplastic resin, heat dissipation substrates can be manufactured at lower temperatures (approximately 250°C to 300°C) and in a shorter time (approximately 10 minutes) than conventional methods. However, the hardened thermoplastic resin has inferior heat resistance and thermal conductivity compared to a metal layer formed by melting and hardening a brazing material. Therefore, the inventors came up with the idea of ​​using a mixture of a powder material containing thermally conductive particles (hereinafter referred to as a "thermal conductive material") and a thermoplastic resin as a bonding material. After various experiments and studies, they came up with the idea of ​​using a thermoplastic resin as a bonding material. 50 It was discovered that when a thermally conductive material containing 70 wt% or more of non-spherical particles (first particles) with a particle diameter of 2 μm or more and 5 μm or less is used, a bonding layer with excellent heat resistance and thermal conductivity can be formed, even though it is an organic bonding material that hardens a thermoplastic resin. The bonding material disclosed here was made based on this finding, and enables the production of high-performance heat dissipation substrates with low-temperature, short-time heat treatment.

[0010] In one embodiment of the bonding material for heat dissipation substrates disclosed herein, the BET specific surface area of ​​the first particles is 0.4 m 2 / g or more 1.2m 2 / g or less, which can further improve the thermal conductivity of the bonding layer.

[0011] In one embodiment of the bonding material for heat dissipation substrates disclosed herein, the thermal conductive material is D 50 The bonding layer further includes second particles having a particle diameter of 0.01 μm or more and 1 μm or less and an average aspect ratio of less than 2. This can further improve the thermal conductivity and bonding strength of the bonding layer.

[0012] In one embodiment of the bonding material for heat dissipation substrates disclosed herein, the content of the second particles is 10 wt% or more and 30 wt% or less when the total mass of the thermally conductive material is 100 wt%, which can further improve the thermal conductivity and bonding strength of the bonding layer.

[0013] In one embodiment of the bonding material for heat dissipation substrates disclosed herein, the BET specific surface area of ​​the second particles is 0.3 m 2 / g or more 2m 2 / g or less, which can further improve the thermal conductivity of the bonding layer.

[0014] In one embodiment of the bonding material for heat dissipation substrates disclosed herein, the content of the thermoplastic resin is 5 wt% or more and 15 wt% or less when the total mass of the bonding material for heat dissipation substrates is 100 wt%, which allows the bonding layer to achieve both high levels of bonding strength and thermal conductivity.

[0015] In one embodiment of the bonding material for heat dissipation substrates disclosed herein, the thermoplastic resin contains at least one selected from the group consisting of polyimide resin, PES resin, silicone resin, and polyamide resin, thereby achieving high levels of both bonding strength and thermal conductivity of the bonding layer.

[0016] Another aspect of the technology disclosed herein provides a method for manufacturing a heat dissipating substrate. The method for manufacturing a heat dissipating substrate disclosed herein is a method for manufacturing a heat dissipating substrate in which a first member and a second member are bonded together. This manufacturing method includes an application step of applying the heat dissipating substrate bonding material having the above-described configuration between the first member and the second member, and a bonding step of heating the heat dissipating substrate bonding material at a temperature equal to or higher than the glass transition point of the thermoplastic resin while applying pressure in a direction in which the first member and the second member approach each other. Because this manufacturing method uses the above-described bonding material, a high-performance heat dissipating substrate can be manufactured by a low-temperature, short-time heat treatment. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a cross-sectional view schematically showing an example of a heat dissipation substrate. DETAILED DESCRIPTION OF THE INVENTION

[0018] Preferred embodiments of the bonding material for heat dissipation substrates disclosed herein are described below. It should be noted that matters other than those specifically mentioned in this specification that are necessary for implementing the technology disclosed herein (e.g., the detailed structure of the heat dissipation substrate and the method for preparing the bonding material) can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and the technical common sense in the relevant field. Furthermore, the notation "A to B" indicating a numerical range in this specification means "greater than or equal to A and less than or equal to B," and includes values ​​greater than A and less than B.

[0019] 1. Heat dissipation board The bonding material for heat dissipation substrates disclosed herein is used for manufacturing heat dissipation substrates. This heat dissipation substrate includes a first member and a second member bonded to one surface of the first member. A bonding layer is formed at the interface between the first member and the second member by thermally curing the bonding material for heat dissipation substrates disclosed herein. The structure of the heat dissipation substrate to be bonded will be described below.

[0020] FIG. 1 is a cross-sectional view schematically illustrating an example of a heat dissipation substrate. The heat dissipation substrate 1 shown in FIG. 1 is a laminate in which a ceramic member 10, a circuit member 20, and a heat dissipation member 30 are stacked. The terms "first member" and "second member" mentioned above refer to two members adjacent to each other in the stacking direction among the constituent members of the heat dissipation substrate. For example, if the circuit member 20 in FIG. 1 is the first member, the second member is the ceramic member 10. Also, if the heat dissipation member 30 is the first member, the second member is the ceramic member 10. A bonding layer 40 is formed at the interface between these first and second members (i.e., the interface between the circuit member 20 and the ceramic member 10, and the interface between the heat dissipation member 30 and the ceramic member 10).

[0021] (1) Ceramic materials The ceramic member 10 is a member that insulates the circuit member 20 from the heat dissipation member 30. Conventionally known ceramic materials having insulating and thermally conductive properties can be used for the ceramic member 10. Examples of such ceramic materials include metal nitrides (nitride-based ceramics), metal oxides (oxide-based ceramics), as well as metal borides, fluorides, hydroxides, carbonates, phosphates, and metal carbides (carbide-based ceramics). Specific examples of nitride-based ceramics include silicon nitride (Si3N4) and aluminum nitride (AlN). Specific examples of oxide-based ceramics include alumina (Al2O3). These ceramics can provide good insulation between the circuit member 20 and the heat dissipation member 30 and have excellent thermal conductivity.

[0022] (2) Circuit components The circuit member 20 is a member bonded to the upper surface 10a of the ceramic member 10. A metal plate is used as the circuit member. Examples of metal plates include copper (Cu), aluminum (Al), silver (Ag), platinum (Pt), and palladium (Pd). To form a circuit member with a circuit formed thereon, a metal plate cut to a predetermined size may be used, or the circuit may be formed by etching the metal plate or the bonding layer. Electronic components are mounted on the upper surface 20a of the circuit member 20.

[0023] (3) Heat dissipation material The heat dissipation member 30 is a plate-like member bonded to the lower surface 10b of the ceramic member 10. Although not shown, a cooling device such as a heat sink is attached to the lower surface 30a of the heat dissipation member 30. In the heat dissipation substrate 1 shown in FIG. 1, heat generated on the circuit member 20 side is transferred to the heat dissipation member 30 via the ceramic member 10. The heat dissipation member 30 is then cooled by the cooling device. This makes it possible to suppress a rise in temperature on the circuit member 20 side. Note that the heat dissipation member 30 can be made of a conventionally known metal material with excellent thermal conductivity. Specific examples of such metal materials include copper (Cu), aluminum (Al), silver (Ag), platinum (Pt), and palladium (Pd). These metal materials have suitable thermal conductivity.

[0024] (4) Bonding layer The bonding layer 40 is a layer that bonds the interfaces of the components of the heat dissipation substrate 1 (ceramic member 10, circuit member 20, and heat dissipation member 30). Specifically, a first bonding layer 42 is formed between the upper surface 10a of the ceramic member 10 and the lower surface 20b of the circuit member 20. A second bonding layer 44 is formed between the lower surface 10b of the ceramic member 10 and the upper surface 30b of the heat dissipation member 30. In order to properly bond these components, the bonding layer 40 is required to have excellent bonding strength. Furthermore, since the bonding layer 40 may be heated to 250°C or higher during use of the electronic component, it is required to have high heat resistance. Furthermore, since the bonding layer 40 is a component that exists on the heat dissipation path from the circuit member 20 side to the heat dissipation member 30 side, it is also required to have excellent thermal conductivity.

[0025] The bonding layer 40 is formed by applying a bonding material between the objects to be bonded (between the ceramic member 10 and the circuit member 20, or between the ceramic member 10 and the heat dissipation member 30) and heating the applied material. The composition of the bonding material disclosed herein will be described below.

[0026] 2. Bonding material for heat dissipation board The bonding material for heat dissipation substrates disclosed herein includes at least (1) a thermoplastic resin and (2) a thermally conductive material. The bonding material disclosed herein may also include (3) an organic solvent and (4) other additives.

[0027] (1)Thermoplastic resin The bonding material disclosed herein contains a thermoplastic resin with a glass transition point of 200°C or higher and 300°C or lower. This thermoplastic resin softens when heated to a temperature above its glass transition point. When the bonding objects are sandwiched and cooled in this state, the thermoplastic resin hardens, forming a bonding layer 40. This bonding method eliminates the need for a firing process to melt metal powder, allowing the heat dissipation substrate 1 to be manufactured at a lower temperature and in a shorter time than conventional methods. Note that if the glass transition point of the thermoplastic resin is too low, the bonding layer 40 may soften due to temperature increases during use of the electronic components. For this reason, the glass transition point of the thermoplastic resin is set to 200°C or higher (preferably 210°C or higher, more preferably 225°C or higher, even more preferably 240°C or higher, and particularly preferably 250°C or higher). On the other hand, a thermoplastic resin with a too high glass transition point is difficult to sufficiently soften by a low-temperature, short-time heat treatment, which reduces the bonding strength of the bonding layer 40 after hardening. For this reason, the glass transition point of the thermoplastic resin is set to 300° C. or lower (preferably 290° C. or lower, more preferably 280° C. or lower).

[0028] The thermoplastic resin is not particularly limited as long as its glass transition point is within an appropriate range, and conventionally known thermoplastic resins can be used without any particular limitation. Specific examples of thermoplastic resins include polyimide resin, PES resin, silicone resin, and polyamide resin. By using these thermoplastic resins, a bonding layer 40 that combines high levels of bonding ability and heat resistance can be easily formed. Furthermore, from the perspective of the performance of the bonding layer 40, the weight-average molecular weight of the thermoplastic resin is not particularly limited. However, as the weight-average molecular weight of the thermoplastic resin increases, the viscosity of the bonding material tends to increase. For this reason, the weight-average molecular weight of the thermoplastic resin is preferably 5,000 or more, more preferably 10,000 or more, and particularly preferably 20,000 or more. This allows for a bonding material that is easily adhered to the interface of the bonding objects to be obtained. On the other hand, the weight-average molecular weight of the thermoplastic resin is preferably 500,000 or less, more preferably 300,000 or less, even more preferably 200,000 or less, and particularly preferably 100,000 or less. This allows for a bonding material that is easily applied to the bonding objects to be obtained.

[0029] Furthermore, the amount of thermoplastic resin added is preferably set in relation to the total mass of the thermally conductive material, which will be described later. This allows the performance of the bonding layer 40 after curing to be appropriately adjusted. For example, the total mass of the thermoplastic resin relative to the total mass of the thermally conductive material (100 wt%) is preferably 1 wt% or more, more preferably 3 wt% or more, and particularly preferably 5 wt% or more. The greater the ratio of the thermoplastic resin relative to the thermally conductive material, the higher the bonding strength of the bonding layer 40. On the other hand, the total mass of the thermoplastic resin relative to the total mass of the thermally conductive material is preferably 20 wt% or less, more preferably 17 wt% or less, and particularly preferably 15 wt% or less. The lower the ratio of the thermoplastic resin relative to the thermally conductive material, the higher the heat resistance and thermal conductivity of the bonding layer 40.

[0030] (2) Thermally conductive material The thermally conductive material is a powder material containing thermally conductive particles. When this thermally conductive material is added to the bonding material, the thermally conductive particles are dispersed within the bonding layer 40 after hardening. This improves the heat resistance and thermal conductivity of the bonding layer 40. The thermally conductive particles are not limited to a specific material and can be selected without particular limitation from known materials that have a certain level of heat resistance and thermal conductivity. Examples of thermally conductive particles include metal particles such as silver (Ag), copper (Cu), aluminum (Al), iron (Fr), nickel (Ni), palladium (Pb), and platinum (Pt). The thermally conductive particles may also be alloy particles containing the above-mentioned metal elements (e.g., Ag-Pd alloy, Ag-Pt alloy, Ag-Cu alloy, Cu-Ni alloy). The thermally conductive particles are not limited to the above-mentioned metal particles. Other examples of thermally conductive particles include ceramic particles such as alumina (Al2O3), zirconia (ZrO2), silica (SiO2), aluminum nitride (AlN), boron nitride (BN), and silicon nitride (SiN), as well as carbon particles such as carbon and diamond. Among the above, silver and copper are particularly suitable because they have excellent heat resistance and thermal conductivity. The thermally conductive material may also be a mixture of multiple types of thermally conductive particles made of different materials. However, from the perspective of stably forming a thermally conductive network, which will be described later, it is preferable that the thermally conductive particles in the thermally conductive material are made of the same material.

[0031] (a) First particle The thermally conductive material of the bonding material disclosed herein is D 50 The thermally conductive material contains at least first particles having a particle diameter of 2 μm to 5 μm and an average aspect ratio of 1.2 or greater. The content of the first particles is set to 70 wt% to 100 wt% when the total mass of the thermally conductive material is 100 wt%. Experiments have confirmed that using a thermally conductive material containing the first particles as described above can significantly improve the heat resistance and thermal conductivity of the cured bonding layer 40. While not intended to limit the technology disclosed herein, the reason for this effect is presumed to be as follows. As described above, the thermally conductive particles improve the heat resistance and thermal conductivity of the bonding layer 40 by dispersing them within the bonding layer 40. However, if the thermally conductive particles are spaced apart, heat applied to the bonding layer 40 easily passes through the thermoplastic resin. In this case, even if the thermally conductive particles are added, the heat resistance and thermal conductivity of the bonding layer 40 are not sufficiently improved. In contrast, the bonding material disclosed herein contains a large amount of non-spherical particles (first particles) with a certain particle diameter or larger and a high aspect ratio. Therefore, a heat conductive network in which multiple heat conductive particles are connected to each other is formed inside the cured bonding layer 40. As a result, heat conduction via the heat conductive particles is promoted, greatly improving the heat resistance and thermal conductivity of the bonding layer 40.

[0032] The first particles will be described in detail below. First, the first particles in this specification are non-spherical particles with an average aspect ratio of 3 or more. Adding a large amount of such non-spherical particles with a high aspect ratio facilitates the formation of a mesh-like heat-conducting network. The average aspect ratio of the first particles is preferably 3.2 or more, more preferably 3.5 or more, even more preferably 3.7 or more, and particularly preferably 4 or more. This allows for the formation of a more suitable heat-conducting network. Meanwhile, the upper limit of the average aspect ratio of the first particles is not particularly limited, and may be 10 or less, 8.5 or less, 8 or less, 7 or less, 6 or less, or 5.5 or less. Furthermore, the first particles may have any of the above-mentioned average aspect ratios, and the specific shape is not particularly limited. Specific examples of the shape of the first particles include flakes (scales), needles, rods, plates, and ellipsoids.

[0033] In this specification, the term "average aspect ratio" refers to the average value of the maximum dimension / minimum dimension of a plurality of particles. In other words, the average maximum dimension, average minimum dimension, and average aspect ratio here are values ​​that indicate the average particle shape of the particles. Specifically, for example, a scanning electron microscope (SEM) is used to observe a predetermined number of particles contained in the composition (for example, at least 100 particles (preferably 200 to 300 particles) randomly selected), and the maximum and minimum dimensions of each particle are determined. The maximum dimension of each particle is then divided by the minimum dimension to calculate the maximum / minimum dimension (aspect ratio) of each particle. The maximum dimensions, minimum dimensions, and average aspect ratio of the predetermined number of particles can then be arithmetically averaged to determine the average maximum dimension, minimum dimension, and average aspect ratio.

[0034] Next, the first particle D 50 The particle diameter is 5 μm or less. It has been confirmed through experiments that the thermal conductivity of the bonding layer 40 decreases when non-spherical particles exceeding 5 μm are added. This is presumably because the heat conduction network in the bonding layer 40 becomes simple when the high aspect ratio non-spherical particles become too large. From the viewpoint of further improving the thermal conductivity of the bonding layer 40, it is preferable to use a first particle having a diameter of 5 μm or less. 50 The particle diameter is preferably 4.9 μm or less, more preferably 4.8 μm or less, even more preferably 4.7 μm or less, and particularly preferably 4.6 μm or less. 50 The lower limit of the particle size is not particularly limited from the viewpoint of improving heat resistance and thermal conductivity. 50 If the particle diameter is too small, the first particles tend to aggregate together. In this case, it is difficult to form an appropriate heat conduction network. From this viewpoint, the D 50 The lower limit of the particle size is set to 2 μm or more (preferably 2.3 μm or more, more preferably 2.5 μm or more, and particularly preferably 2.8 μm or more). 50 The "particle size" is the particle size corresponding to the cumulative 50% from the smallest particle size side in the volume-based particle size distribution determined by a laser diffraction particle size distribution measuring device.

[0035] Next, the content of the first particles relative to the total mass of the thermally conductive material is 70 wt% or more. Experiments have confirmed that the thermal conductivity of the bonding layer 40 decreases when the content of the first particles is less than 70 wt%. This is presumably due to a shortage of the first particles, which are the main material of the thermally conductive network. Furthermore, if an excessive amount of thermally conductive particles, which are finer than the first particles, is added, the bonding strength may decrease significantly. This is presumably due to the thermoplastic resin in the bonding layer 40 being divided by the thermally conductive particles. Note that, from the viewpoint of forming a bonding layer 40 with excellent thermal conductivity and bonding strength, the content of the first particles is preferably 75 wt% or more, and particularly preferably 80 wt% or more. Meanwhile, there is no particular upper limit to the content of the first particles. For example, the thermally conductive material may be entirely made of first particles (the content of the first particles is 100 wt%). Experiments have confirmed that a high-performance bonding layer 40 can be formed even in this case. However, taking into consideration the addition of second particles described below, the upper limit of the content of the first particles is preferably 99 wt % or less, more preferably 95 wt % or less, and particularly preferably 90 wt % or less.

[0036] The BET specific surface area of ​​the first particle is 0.4 m 2 / g or more is preferable, and 0.45m 2 / g or more is more preferable, and 0.5m 2 / g or more is more preferable, and 0.55m 2 / g or more is particularly preferred. As the BET specific surface area increases, the first particles tend to come into contact with each other, and a more suitable heat conduction network can be formed. On the other hand, if the BET specific surface area is too large, the first particles tend to aggregate with each other. From this perspective, the BET specific surface area of ​​the first particles is 1.2 m 2 / g or less is preferable, and 1m 2 / g or less is more preferable, and 0.8m 2 / g or less is particularly preferred.

[0037] (b) Second particle In addition, the thermal conductive material is D 50It is preferable to further include second particles having a particle diameter of 0.01 μm or more and 1 μm or less and an average aspect ratio of less than 2.0. This has been confirmed to further improve the bonding strength and thermal conductivity of the bonding layer 40. The reason for this effect is presumed to be as follows. The second particles are spherical particles smaller than the first particles. When these first particles and second particles are mixed, a complex thermal conductive network is formed in which large non-spherical particles (first particles) are connected via the small spherical particles (second particles). This is presumed to further improve the thermal conductivity of the bonding layer 40. Furthermore, when the position of the thermal conductive particles in the bonding layer 40 becomes complex, the thermoplastic resin and the thermal conductive particles are firmly bonded due to an anchor effect. This is presumed to further improve the bonding strength of the bonding layer 40.

[0038] As described above, the second particles in this specification are spherical particles with an average aspect ratio of less than 2.0. Such spherical particles easily enter the gaps between the first particles, which are non-spherical particles. This allows for the formation of a more suitable heat conduction network. Furthermore, the average aspect ratio of the second particles is preferably 1.8 or less, more preferably 1.5 or less, and particularly preferably 1.3 or less. This allows for the formation of a more suitable heat conduction network. Meanwhile, the lower limit of the average aspect ratio of the second particles is 1 or more (i.e., a perfect sphere).

[0039] Also, the second particle D 50 The particle diameter is 1 μm or less. This allows the second particles to more easily enter the gaps between the first particles, thereby forming a more suitable heat conduction network. From the viewpoint of further improving the thermal conductivity of the bonding layer 40, the D 50 The particle diameter is preferably 0.9 μm or less, particularly preferably 0.8 μm or less. 50 If the particle diameter is too small, the second particles will aggregate, making it difficult for the second particles to enter the gaps between the first particles. 50The particle size is set to 0.01 μm or more (preferably 0.05 μm or more, more preferably 0.1 μm or more, even more preferably 0.15 μm or more, and particularly preferably 0.2 μm or more).

[0040] Furthermore, the content of the second particles relative to the total mass of the thermally conductive material is preferably 1 wt% or more, more preferably 5 wt% or more, and particularly preferably 8 wt% or more. This allows a sufficient amount of the second particles to enter the gaps between the non-spherical first particles, forming a more suitable thermally conductive network. On the other hand, if there are too many microscopic second particles, the thermoplastic resin of the bonding layer 40 is likely to be disrupted by the thermally conductive particles. In this case, the bonding strength of the bonding layer 40 may be significantly reduced. From this perspective, the content of the second particles is preferably 30 wt% or less, more preferably 25 wt% or less, and particularly preferably 20 wt% or less.

[0041] The BET specific surface area of ​​the second particle is 0.3 m 2 / g or more is preferable, and 0.35m 2 / g or more is more preferable, and 0.4m 2 / g or more is more preferable, and 0.45m 2 / g or more is particularly preferred. If the BET specific surface area of ​​the second particles is large, the contact area with the first particles becomes large, and therefore a suitable heat conduction network is more likely to be formed. On the other hand, if the BET specific surface area is too large, the second particles are more likely to aggregate with each other. From this perspective, the BET specific surface area of ​​the first particles is preferably 2 m 2 / g or less is preferable, and 1.5m 2 / g or less is more preferable, and 1m 2 / g or less is particularly preferred.

[0042] The surfaces of the second particles are preferably coated with an organic protective layer. This can suppress aggregation of the second particles. It has also been confirmed that when an organic protective layer is formed on the surface of microparticles of 1 μm or less, the second particles can be sintered by heating at a temperature lower than the melting point of the second particles. This allows the first particles to be sintered via the second particles even at low temperatures that do not burn off the thermoplastic resin. While not limiting the technology disclosed herein, this phenomenon is presumed to be due to the decomposition of the organic protective layer during heating and the reduction of the surfaces of the second particles. The components of the organic protective layer are not particularly limited, and conventionally known organic components used to protect this type of inorganic particles can be used without particular limitation.

[0043] (c) Other heat-conducting particles The thermally conductive material may contain thermally conductive particles other than the first and second particles. Examples of the other thermally conductive particles include third particles, which are spherical particles larger than the second particles, fourth particles, which are non-spherical particles smaller than the first particles, and fifth particles, which have an aspect ratio intermediate between the first and second particles. Specifically, the third particles are D 50 The fourth particle is a thermally conductive particle having a particle diameter of more than 1 μm and an average aspect ratio of less than 2. 50 The fifth particles refer to thermally conductive particles having a particle diameter of less than 2 μm and an average aspect ratio of 3 or more. The fifth particles refer to thermally conductive particles having an average aspect ratio of 2 or more but less than 3. Even when these thermally conductive particles are contained, a thermally conductive material containing 70 wt% or more of the first particles described above can form a bonding layer 40 with favorable performance. However, if a large amount of other thermally conductive particles is contained, the formation of a thermally conductive network may be hindered. For this reason, the content of other thermally conductive particles relative to the total mass of the thermally conductive material is preferably 20 wt% or less, more preferably 10 wt% or less, even more preferably 5 wt% or less, and particularly preferably 1 wt% or less. Furthermore, from the perspective of forming a more favorable thermally conductive network, it is preferable that the thermally conductive material does not contain any thermally conductive particles other than the first and second particles (i.e., the content of other thermally conductive particles is 0 wt%).

[0044] (3) Organic solvents The bonding material disclosed herein may contain an organic solvent. The organic solvent may be any solvent capable of dissolving a thermoplastic resin, without any particular limitation. This allows the preparation of a bonding material that can be easily applied to the bonding objects. However, the bonding material does not need to contain an organic solvent as long as it has a viscosity that allows it to be appropriately applied to the bonding objects.

[0045] The organic solvent for the bonding material disclosed herein preferably evaporates at a temperature below the glass transition point of the thermoplastic resin. This allows the organic solvent to evaporate during the heat treatment for curing the thermoplastic resin, facilitating the formation of the bonding layer 40. Examples of such organic solvents include alcohol-based solvents such as terpineol, texanol, dihydroterpineol, and benzyl alcohol; glycol-based solvents such as ethylene glycol and diethylene glycol; glycol ether-based solvents such as diethylene glycol monoethyl ether, butyl carbitol (diethylene glycol monobutyl ether), and triethylene glycol dimethyl ether; ester-based solvents such as isobornyl acetate, ethyl diglycol acetate, butyl glycol acetate, butyl diglycol acetate, butyl cellosolve acetate, butyl carbitol acetate (diethylene glycol monobutyl ether acetate), γ-butyrolactone, methyl benzoate, and propylene carbonate; hydrocarbon-based solvents such as toluene and xylene; aprotic polar solvents such as N-methylpyrrolidone (NMP), and mineral spirits. The organic solvent may be a mixture of two or more of the above-mentioned solvents.

[0046] The content of the organic solvent in the bonding material is not particularly limited. For example, when the entire bonding material is taken as 100% by mass, the content of the organic solvent may be 1% by mass to 70% by mass, 5% by mass to 60% by mass, or 10% by mass to 50% by mass. However, the content of the organic solvent is not limited to the above range, and may be appropriately adjusted to achieve a viscosity that makes it easy to apply to the bonding objects.

[0047] (4) Other ingredients The bonding material disclosed herein may contain various additives as needed. As additives, conventionally known additives that can be used in general organic bonding materials can be appropriately selected as long as they do not significantly impair the effects of the technology disclosed herein. Examples of such additives include dispersants, antifoaming agents, leveling agents, and antioxidants.

[0048] 3. Heat dissipation substrate manufacturing method According to the technology disclosed herein, there is provided a method for manufacturing a heat dissipation substrate using the bonding material having the above-described configuration. The method for manufacturing a heat dissipation substrate includes a coating step and a bonding step. The manufacturing method will be described below.

[0049] (1) Coating process In the application step, the bonding material having the above-described configuration is applied between the first member and the second member. As described above, the first member and the second member here refer to two members adjacent in the stacking direction among the constituent members of the heat dissipation substrate. For example, if the circuit member 20 in FIG. 1 is the first member, the second member is the ceramic member 10. Also, if the heat dissipation member 30 is the first member, the second member is the ceramic member 10. The bonding material disclosed herein forms a bonding layer 40 between these members.

[0050] The means for applying the bonding material is not particularly limited, and any conventionally known application means (such as screen printing) can be used without any particular restrictions. The bonding material is then applied to one (or both) of the first and second members, and the respective components are laminated. This allows the bonding material to be applied between the first and second members. Furthermore, the applied bonding material may be subjected to a drying process. This prevents the bonding material from flowing out before hardening.

[0051] (3)Joining process In the bonding process, the heat dissipation substrate bonding material is heated while applying pressure in a direction that brings the first and second members closer together. In the manufacturing method disclosed herein, when the glass transition point of the thermoplastic resin is X°C, the heating temperature in the bonding process is set to X±50°C. This bonds the first and second members. Specifically, when the bonding material is heated near the glass transition point of the thermoplastic resin (i.e., within a range of ±50°C), the thermoplastic resin softens. When the bonding objects are sandwiched and cooled in this state, the thermoplastic resin hardens, allowing the bonding objects to be bonded. The heating temperature in this process varies depending on the glass transition point of the thermoplastic resin and is not limited to a specific temperature. However, the glass transition point of the thermoplastic resin is at most 300°C. Therefore, in the manufacturing method disclosed herein, the constituent members of the heat dissipation substrate can be bonded without performing a baking process at a high temperature (approximately 900°C) that would melt the metal powder.

[0052] Furthermore, in the manufacturing method disclosed herein, the bonding material can be sufficiently hardened even if the heating time is set to 120 minutes or less (preferably 60 minutes or less, more preferably 45 minutes or less, even more preferably 30 minutes or less, and particularly preferably 20 minutes or less). This allows for significant reductions in environmental impact and manufacturing costs. Meanwhile, the heating time in this step is preferably 5 minutes or more, more preferably 7.5 minutes or more, and particularly preferably 10 minutes or more. This prevents a decrease in bonding strength due to insufficient softening of the bonding material.

[0053] The surface pressure when clamping the first member and the second member is preferably 5 MPa or more, and particularly preferably 15 MPa or more. This can prevent a decrease in bonding strength due to the occurrence of a gap between the bonding objects and the bonding layer 40. On the other hand, the upper limit of the surface pressure in the bonding process may be 200 MPa or less, 150 MPa or less, 100 MPa or less, or 50 MPa or less.

[0054] As described above, by using the bonding material disclosed herein, it is possible to bond the components of a heat dissipation substrate without performing high-temperature, long-term firing treatment. Furthermore, the bonding material disclosed herein can form a bonding layer 40 that has excellent heat resistance, thermal conductivity, and bonding strength. Therefore, the technology disclosed herein makes it possible to easily manufacture a high-performance heat dissipation substrate.

[0055] 4. Other Embodiments One embodiment of the technology disclosed herein has been described above. However, the technology disclosed herein is not limited to the above-described embodiment. The technology disclosed herein encompasses various modifications and variations of the above-described embodiment.

[0056] In the above-described embodiment, a heat dissipation substrate 1 having a three-layer structure including a ceramic member 10, a circuit member 20, and a heat dissipation member 30 is manufactured. However, the technology disclosed herein is not limited to the structure of the manufactured object (heat dissipation substrate). For example, some heat dissipation substrates have an intermediate layer interposed between the above-mentioned components to improve performance. The bonding material disclosed herein can also be used to bond this intermediate layer to other components (such as ceramic members, circuit members, and heat dissipation members).

[0057] The bonding material disclosed herein can also contribute to the realization of a two-layer heat dissipation substrate. A typical heat dissipation substrate has a structural characteristic in which the difference in thermal expansion coefficient between the metal plate and the ceramic member is very large. In contrast, conventional bonding materials (brazing filler metals) cannot mitigate the difference in thermal expansion coefficient between the two members, resulting in a risk of the substrate curvature after firing. For this reason, conventional manufacturing methods have suppressed substrate curvature by bonding metal plates to both sides of the ceramic member. In contrast, the bonding material disclosed herein is a flexible bonding material containing a thermoplastic resin. This flexible bonding material can mitigate stress between the metal plate and the ceramic member. As a result, even when a metal plate is bonded to only one side of the ceramic member, the substrate can be less curved. In other words, the bonding material disclosed herein can mitigate stress between the metal plate and the ceramic member, thereby realizing a two-layer heat dissipation substrate in which a ceramic member and a circuit member are bonded.

[0058] [Test example] Test examples relating to the technology disclosed herein will be described below. Note that the following description is not intended to limit the technology disclosed herein to the content shown in the test examples.

[0059] <First test> In this test, we investigated thermoplastic resins suitable for joining ceramic parts and metal parts.

[0060] 1. Sample Preparation (1) Sample 1 In this sample, D 50 The first particles are flake-shaped Ag particles (average aspect ratio: 5.5) with a particle diameter of 2.8 μm, and the second particles are D 50A thermal conductive material was used, which was a mixture of first particles and second particles, which were spherical Ag particles with a particle diameter of 0.2 μm (average aspect ratio: 1.4). The mixing ratio of the first particles to the second particles in the thermal conductive material of Sample 1 was 90:10. Next, in Sample 1, a polyester resin with a glass transition point of 70°C was used as the thermoplastic resin. The content of the thermoplastic resin was set to 9 wt% when the total weight of the thermal conductive material was 100 wt%. Next, in this test, γ-butyrolactone was used as the organic solvent. The content of the organic solvent was set to 25 wt% when the total weight of the thermal conductive material was 100 wt%. The above materials were kneaded using a three-roll mill to prepare the bonding material of Sample 1.

[0061] (2) Sample 2 For Sample 2, the bonding material was prepared under the same conditions as for Sample 1, except that the thermoplastic resin was changed to a polyimide resin (glass transition point: 185°C).

[0062] (3) Sample 3 For Sample 3, the bonding material was prepared under the same conditions as for Sample 1, except that the thermoplastic resin was changed to a polyimide resin (glass transition point: 250° C.).

[0063] (4) Sample 4 For Sample 4, the bonding material was prepared under the same conditions as for Sample 1, except that the thermoplastic resin was changed to a polyimide resin (glass transition point: 270°C).

[0064] (5) Sample 5 For Sample 5, the bonding material was prepared under the same conditions as for Sample 1, except that the thermoplastic resin was changed to a polyimide resin (glass transition point: 320° C.).

[0065] (6) Sample 6 For Sample 6, the bonding material was prepared under the same conditions as for Sample 1, except that the thermoplastic resin was changed to PES resin (glass transition point: 225°C).

[0066] 2.Evaluation Test (1) Preparation of the laminate In this test, an alumina plate and a copper plate were prepared as the objects to be joined. A bonding material was applied to the surface of the alumina plate. The area of ​​the applied area was set to 2 cm x 2 cm. The thickness of the applied material was set to 20 μm. The bonding material on the alumina plate was then dried by heat treatment at 130°C for 15 minutes. Next, a copper plate was stacked on top of the dried bonding material, and a hardening process was performed using a high-precision hot press machine (manufactured by Tester Sangyo Co., Ltd.) while applying a surface pressure of 30 MPa. This hardening process involved heat treatment at 280°C for 15 minutes. This resulted in the production of a test piece in which the alumina plate and the copper plate were bonded via the bonding layer.

[0067] (2) Bond strength evaluation The alumina and copper test pieces were fixed to the upper and lower chucks of a tensile testing machine (Shimadzu Corporation, Universal Testing Machine Autograph), and tensile shear tests were performed in accordance with JIS K6850:1999, JIS C5016-1994, and JIS C6481-1996. Specifically, a tensile load perpendicular to the bonded surface of the test piece was applied at a specified loading rate. The adhesive strength of the bonding layer was measured from the tensile load (breaking force) at which the test piece broke. The measurement results were evaluated using the following indices. The results are shown in the "Bonding Strength" column of Table 1.

[0068] "◎": Adhesion strength is 5N / mm 2 That was all. "Good": Adhesive strength is 2N / mm 2 More than 5N / mm 2 It was less than. "△": Adhesive strength is 1N / mm 2 More than 2N / mm 2 It was less than. "×": Adhesion strength is 1N / mm 2 It was less than.

[0069] (3) Heat resistance evaluation In this test, test pieces for evaluating heat resistance were prepared and evaluated. First, each bonding material was applied to a film so that the thickness after curing was approximately 200 μm. Then, the bonding material was cured by heat treatment at 280°C for 90 minutes. The cured bonding material was then cut into pieces measuring 1 x 4 cm to prepare test pieces. For the heat resistance evaluation, these test pieces were heat treated at 200°C for 3,000 hours. The weight ratio (%) of the test piece after heat treatment was measured, assuming the weight of the test piece before heat treatment was 100 wt%. The measurement results were evaluated using the following indices. The results are shown in the "Heat Resistance" column in Table 1.

[0070] "Excellent": The weight loss rate was 10% or less. "Good": The weight loss rate was more than 10% and 30% or less. "△": The weight loss rate was more than 30% and 50% or less. "X": The weight loss rate was more than 50%.

[0071] (4) Thermal conductivity evaluation In this test, test pieces for evaluating thermal conductivity were prepared and evaluated. In this test, each bonding material was first applied to a coating so that the thickness after curing was approximately 500 μm. The bonding material was then cured by heat treatment at 280°C for 90 minutes. The cured bonding material was then cut into 1 x 1 cm pieces to prepare test pieces. The thermal conductivity of these test pieces was then measured using a cyclic heating radiation thermometer (Bethel Thermowave Analyzer TA). The measurement results were evaluated using the following indices. The results are shown in the "Thermal Conductivity" column of Table 1.

[0072] "Excellent": Thermal conductivity was 80 or more. "Good": Thermal conductivity was 50 or more and less than 80. "△": Thermal conductivity was 30 or more and less than 50. "X": The thermal conductivity was less than 30.

[0073] (5) Overall evaluation In this test, each sample was comprehensively evaluated based on the above-mentioned evaluation criteria.

[0074] "◎": All evaluations were "◎". "Good": There was at least one "Good" in each evaluation, and no "Good" or "Poor" ratings. "△": There was at least one "△" in each evaluation and no "×" "×": There was one or more "×" in each evaluation.

[0075] [Table 1]

[0076] As shown in Table 1, in the first test, samples 3, 4, and 6 were confirmed to have excellent bonding layer performance. Specifically, it was found that to ensure excellent bonding strength, it is necessary to use a thermoplastic resin with a glass transition point of 300°C or less. It was also found that to ensure excellent heat resistance, it is necessary to use a thermoplastic resin with a glass transition point of 200°C or more. Furthermore, a comparison of sample 2 and sample 6 revealed that the bonding strength and heat resistance of the bonding layer are largely influenced by the glass transition point of the thermoplastic resin, rather than the type of thermoplastic resin.

[0077] <Second test> In this test, the appropriate content of thermoplastic resin was investigated.

[0078] 1. Sample Preparation (1) Sample 7 For Sample 7, the bonding material was prepared under the same conditions as for Sample 4 in the first test, except that the content of the thermoplastic resin relative to the total mass (100 wt%) of the thermal conductive material was changed to 3 wt%.

[0079] (2) Sample 8 For Sample 8, the bonding material was prepared under the same conditions as for Sample 4 in the first test, except that the content of the thermoplastic resin relative to the total mass (100 wt%) of the thermal conductive material was changed to 5 wt%.

[0080] (3) Sample 9 For Sample 9, the bonding material was prepared under the same conditions as for Sample 4 in the first test, except that the content of the thermoplastic resin relative to the total mass (100 wt%) of the thermal conductive material was changed to 15 wt%.

[0081] (4) Sample 10 For Sample 10, the bonding material was prepared under the same conditions as for Sample 4 in the first test, except that the content of the thermoplastic resin relative to the total mass (100 wt%) of the thermal conductive material was changed to 17 wt%.

[0082] 2.Evaluation Test In the second test, test pieces were prepared according to the same procedure as in the first test. The bond strength, heat resistance, and thermal conductivity of these test pieces were then evaluated. The results are shown in Table 2.

[0083] [Table 2]

[0084] As shown in Table 2, excellent bonding layers were formed in all of Samples 7 to 10. Among these, Samples 8 and 9 exhibited particularly high performance. This indicates that the preferred range of thermoplastic resin content relative to the total mass of the thermal conductive material is 5 wt% to 15 wt%.

[0085] <Third Test> In this test, we investigated suitable thermal conductive materials.

[0086] 1. Sample Preparation (1) Sample 11 For Sample 11, the bonding material was prepared under the same conditions as for Sample 4 in the first test.

[0087] (2) Sample 12 In Sample 12, the bonding material was prepared under the same conditions as Sample 11, except that the type of the first particles was changed.50 The Ag particles are flake-shaped (average aspect ratio: 8.5) with a particle diameter of 4.65 μm.

[0088] (3) Sample 13 In Sample 13, the bonding material was prepared under the same conditions as Sample 11, except that a thermal conductive material containing third particles was used. Specifically, the third particles added in Sample 13 were D 50 The Ag particles were spherical (average aspect ratio: 1.2) with a particle diameter of 3.2 μm, and the content ratio of the first particles, the second particles, and the third particles in the thermal conductive material of Sample 13 was 70:10:20.

[0089] (4) Sample 14 For Sample 14, the bonding material was prepared under the same conditions as for Sample 11, except that a thermally conductive material consisting only of the first particles (i.e., a first particle content of 100 wt%) was used. Note that the first particles used in Sample 14 are the same as those in Sample 11.

[0090] (5) Sample 15 In Sample 15, the bonding material was prepared under the same conditions as Sample 11, except that the type of second particles was changed. 50 The particles are spherical Ag particles with a particle diameter of 0.8 μm (average aspect ratio: 1.1).

[0091] (6) Sample 16 For Sample 16, the bonding material was prepared under the same conditions as Sample 11, except that the ratio of the first particles to the second particles was changed. Specifically, the content ratio of the first particles to the second particles in the thermal conductive material of Sample 16 was 80:20. The first particles and second particles used in Sample 16 were the same as those in Sample 11.

[0092] (7) Sample 17 In Sample 17, the bonding material was prepared under the same conditions as Sample 11, except that the type of first particles was changed. 50The Ag particles are flake-shaped (aspect ratio: 7.0) with a particle diameter of 5.5 μm.

[0093] (8) Sample 18 For Sample 18, the bonding material was prepared under the same conditions as Sample 13, except that the ratio of the first particles, the second particles, and the third particles was changed. Specifically, the content ratio of the first particles, the second particles, and the third particles in the thermal conductive material of Sample 18 was 50:10:40. The first particles, the second particles, and the third particles used in Sample 18 were the same as those in Sample 13.

[0094] (9) Sample 19 For Sample 19, the bonding material was prepared under the same conditions as for Sample 11, except that the ratio of the first particles to the second particles was changed. Specifically, the content ratio of the first particles to the second particles in the thermal conductive material of Sample 19 was 50:50. The first particles and second particles used in Sample 19 were the same as those in Sample 11.

[0095] 2.Evaluation Test In the third test, test pieces were prepared according to the same procedure as in the first test. The test pieces were then evaluated for bonding strength, heat resistance, and thermal conductivity. The results are shown in Table 3.

[0096] [Table 3]

[0097] As shown in Table 3, in Samples 11 to 16, bonding layers with excellent overall performance were formed. On the other hand, in Sample 17, the thermal conductivity of the bonding layer was reduced. This is due to the D 50It is speculated that this is because the particle diameter became too large, resulting in a simplified heat conduction network within the bonding layer. Furthermore, a decrease in the thermal conductivity of the bonding layer was confirmed in Sample 18 as well. This is speculated to be because a large amount of coarse spherical particles (third particles) was mixed in, preventing the formation of an appropriate heat conduction network. Next, a decrease in bonding strength was confirmed in Sample 19. This is speculated to be because a large amount of minute spherical particles (second particles) was mixed in, making it difficult to ensure the continuity of the thermoplastic resin. Furthermore, the results of Sample 14 showed that even when using a thermal conductive material consisting only of first particles, it was possible to form a bonding layer with excellent bonding strength, heat resistance, and thermal conductivity. From the above results, it can be seen that the thermal conductive material is D 50 It was found that it is sufficient to include at least 70 wt % or more of first particles having a particle diameter of 2 μm or more and 5 μm or less and an average aspect ratio of 1.2 or more.

[0098] The technology disclosed herein has been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above. In other words, the technology disclosed herein encompasses the aspects described in items 1 to 9 below.

[0099] <Item 1> A bonding material for a heat dissipation substrate used to bond components of a heat dissipation substrate, a thermoplastic resin having a glass transition point of 200°C or higher and 300°C or lower; D 50 a thermal conductive material including at least first particles having a particle diameter of 2 μm or more and 5 μm or less and an average aspect ratio of 3 or more; Contains The bonding material for a heat dissipation substrate, wherein the content of the first particles is 70 wt% or more and 100 wt% or less when the total mass of the thermally conductive material is 100 wt%.

[0100] <Item 2> The BET specific surface area of ​​the first particles is 0.4 m 2 / g or more 1.2m 2 2. The bonding material for heat dissipation boards according to item 1, wherein the bonding strength is 1 / g or less.

[0101] <Item 3> The thermally conductive material is D 50 3. The bonding material for heat dissipation substrates according to item 1 or 2, further comprising second particles having a particle diameter of 0.01 μm or more and 1 μm or less and an average aspect ratio of less than 2.

[0102] <Item 4> 4. The bonding material for heat dissipation boards according to item 3, wherein the content of the second particles is 10 wt% or more and 30 wt% or less when the total mass of the thermally conductive material is 100 wt%.

[0103] <Item 5> The BET specific surface area of ​​the second particles is 0.3 m 2 / g or more 2m 2 5. The bonding material for heat dissipation boards according to item 3 or 4, wherein the bonding strength is 1 / g or less.

[0104] <Item 6> 6. The bonding material for heat dissipation boards according to any one of items 1 to 5, wherein the total mass of the thermoplastic resin relative to the total mass of the thermally conductive material is 5 wt % or more and 15 wt % or less.

[0105] <Item 7> 7. The bonding material for heat dissipation boards according to any one of items 1 to 6, wherein the thermoplastic resin includes at least one selected from the group consisting of polyimide resin, PES resin, silicone resin, and polyamide resin.

[0106] <Item 8> A method for manufacturing a heat dissipation substrate in which a first member and a second member are bonded, comprising: a coating step of coating the heat dissipation board bonding material according to any one of items 1 to 7 between the first member and the second member; a bonding process in which the heat dissipation board bonding material is heated while applying pressure in a direction in which the first member and the second member approach each other; It is equipped with When the glass transition point of the thermoplastic resin is X°C, the heating temperature in the bonding step is X±50°C.

[0107] <Item 9> A first member; a second member joined to one surface of the first member; and A heat dissipating substrate, wherein a bonding layer is formed at the interface between the first member and the second member by thermally curing the bonding material for a heat dissipating substrate according to any one of items 1 to 7. [Explanation of symbols]

[0108] 1 Heat dissipation board 10 Ceramic materials 20 Circuit components 30 Heat dissipation material 40 Bonding layer

Claims

1. A bonding material for a heat dissipation substrate used to bond components of a heat dissipation substrate, a thermoplastic resin having a glass transition point of 200°C or higher and 300°C or lower; D ５０ a thermal conductive material including at least first particles having a particle diameter of 2 μm or more and 5 μm or less and an average aspect ratio of 3 or more; Contains A bonding material for a heat dissipation substrate, wherein the content of the first particles is 70 wt % or more and 100 wt % or less when the total mass of the thermal conductive material is 100 wt %.

2. The BET specific surface area of ​​the first particles is 0.4 m ２ / g or more 1.2m ２ The bonding material for heat dissipation substrates according to claim 1, wherein the bonding strength is 1 / g or less.

3. The thermally conductive material is D ５０ The bonding material for heat dissipation substrates according to claim 1 , further comprising second particles having a particle diameter of 0.01 μm or more and 1 μm or less and an average aspect ratio of less than 2.

4. The bonding material for heat dissipation substrates according to claim 3 , wherein the content of the second particles is 10 wt % or more and 30 wt % or less when the total mass of the thermally conductive material is 100 wt %.

5. The BET specific surface area of ​​the second particles is 0.3 m ２ / g or more 2m ２ The bonding material for heat dissipation substrates according to claim 3, wherein the bonding material has a viscosity of 1000 MPa or less.

6. 2. The bonding material for heat dissipation substrates according to claim 1, wherein a total mass of the thermoplastic resin relative to a total mass of the thermally conductive material is 5 wt% or more and 15 wt% or less.

7. The bonding material for heat dissipation substrates according to claim 1 , wherein the thermoplastic resin comprises at least one selected from the group consisting of polyimide resin, PES resin, silicone resin, and polyamide resin.

8. A method for manufacturing a heat dissipation substrate in which a first member and a second member are bonded, comprising: a coating step of coating the heat dissipation substrate bonding material according to any one of claims 1 to 7 between the first member and the second member; a bonding process of heating the heat dissipation board bonding material while applying pressure in a direction in which the first member and the second member approach each other; It is equipped with When the glass transition point of the thermoplastic resin is X°C, the heating temperature in the bonding step is X±50°C.

9. A first member; a second member joined to one surface of the first member; Equipped with A heat dissipation substrate, wherein a bonding layer formed by thermally curing the bonding material for a heat dissipation substrate according to any one of claims 1 to 7 is formed at the interface between the first member and the second member.

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