Thermal interface bonding member and method for manufacturing the same

Abstract

To provide a thermal interface bonding member whose manufacturing process is easy and which can improve thermal conductivity, and to provide a method for manufacturing the same.SOLUTION: A thermal interface bonding member 3 is formed of a cured product of a thermosetting resin. A manufacturing method includes a hot-pressing process of polymerizing and curing a monomer of the thermosetting resin. For example, the hot-pressing process includes a first step of performing heating at a first temperature, a second step of performing pressurization while performing heating at a second temperature equal to or higher than the melting point of the monomer of the thermosetting resin after the first step, and a third step of performing pressurization while performing heating at a third temperature equal to or higher than the curing temperature of the thermosetting resin after the second step. The second temperature is higher than the first temperature, and the third temperature is higher than the second temperature.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a thermal interface bonding member and a method for manufacturing the same. [Background technology]

[0002] Since the performance of electronic devices is often determined by the solid-state bonding interface between the electronic device and the circuit board, the performance of the thermal interface material (TIM) that electrically, thermally, and mechanically bonds the solid-state interface is important. Conventionally, composite materials made of flexible organic polymer resins and highly thermally conductive fillers have been used as TIMs, but their thermal conductivity and heat resistance are insufficient.

[0003] Non-Patent Document 1 discloses a TIM containing vertically aligned carbon nanotubes and a thermosetting resin. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Yoshihiro Takahashi, Taketo Yokoi, Toshio Osawa, Masaki Minami, and Masaru Noda, "Development of Heat-Resistant Thermal Interface Materials Using Thermosetting Resins," The Society of Chemical Engineers, 88th Annual Meeting, Abstracts, PA139 (March 2023) Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the TIM disclosed in Non-Patent Document 1 is used, the manufacturing process is complicated, and further improvement in thermal conductivity is desired.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a thermal interface bonding member that can be easily manufactured and has improved thermal conductivity, and a method for manufacturing the same. [Means for solving the problem]

[0007] The thermal interface bonding member according to the present invention is made of a cured product of a thermosetting resin.

[0008] The method for manufacturing a thermal interface bonding member according to the present invention manufactures a thermal interface bonding member made of a cured thermosetting resin by a manufacturing method including a heat pressing step in which a thermosetting resin monomer is polymerized and cured. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a thermal interface bonding member that can be easily manufactured and has improved thermal conductivity, and a method for manufacturing the same. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view of a thermal interface bonding member according to an embodiment. [Figure 2] FIG. 2 is an enlarged view of the thermal interface bonding member of FIG. [Figure 3] FIG. 3 is a schematic diagram showing a method for manufacturing a thermal interface bonding member according to an embodiment. [Figure 4] FIG. 4 is a diagram showing an example of a temperature profile of a heat pressing process performed in three steps. [Figure 5] FIG. 5 is a schematic diagram of a sample for measuring thermal resistance. [Figure 6] FIG. 6 is a graph showing the change in thermal resistance with respect to the heating temperature in the first example. [Figure 7] FIG. 7 is a diagram showing the measurement results of the thermal resistance evaluation according to the second example. [Figure 8] FIG. 8 is a diagram comparing thermal resistance values ​​according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Exemplary embodiments of the present invention will now be described in detail with reference to the drawings.

[0012] 1. Overall structure 1 is a schematic cross-sectional view of a thermal interface bonding member 3 according to this embodiment. The thermal interface bonding member 3 is provided between a first surface 1A to be bonded of a first member 1 and a second surface 2A to be bonded of a second member 2 to be bonded. The thermal interface bonding member 3 bonds the first member 1 to the second member 2 to be bonded.

[0013] The thermal interface bonding member 3 is made only of a cured thermosetting resin. The thermal interface bonding member 3 does not contain any substance other than the cured thermosetting resin, such as a filler. Examples of thermosetting resins include epoxy resin, phenol resin, melamine resin, urea resin, unsaturated polyester resin, diallyl phthalate resin, polyurethane resin, silicone resin, polyimide resin, and mixtures thereof.

[0014] The thermosetting resin preferably includes an epoxy resin. Examples of the epoxy resin include multifunctional epoxy resins having multiple epoxy groups per molecule. Examples of the epoxy resin include aromatic epoxy resins, aliphatic epoxy resins, and alicyclic epoxy resins. Specific examples of the epoxy resin include bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, bisphenol fluorene epoxy resins, dicyclopentadiene epoxy resins, naphthalene epoxy resins, phenol-biphenylene epoxy resins, cresol novolac epoxy resins, phenol aralkyl epoxy resins, alicyclic epoxy resins, tetrabromobisphenol A epoxy resins, aminophenol epoxy resins, aminotriazine epoxy resins, and mixtures thereof.

[0015] More preferably, the thermosetting resin contains a mixture of an epoxy resin and a phenolic resin. The epoxy resins described above can be used. Examples of the phenolic resin include phenolic resins obtained by reacting polyfunctional phenols with aldehydes or the like. The phenolic resin may also be a phenolic resin obtained by further reacting a monofunctional phenol. Examples of the phenolic resin include novolac-type phenolic resins and resol-type phenolic resins. Specific examples of the phenolic resin include benzoxazine resins, in which molecules having a benzoxazine ring undergo ring-opening polymerization to form polybenzoxazines containing a phenolic structure.

[0016] FIG. 2 is an enlarged view of the thermal interface bonding member 3 in FIG. 1. The first bonded surface 1A of the first bonded member 1 and the second bonded surface 2A of the second bonded member 2 are solid, flat surfaces, but have microscopic irregularities. The thermosetting resin that constitutes the thermal interface bonding member 3 is provided so as to fill the gaps caused by the microscopic irregularities of the first bonded surface 1A and the second bonded surface 2A. The first bonded surface 1A and the second bonded surface 2A are in direct contact in part, as indicated by circle 4 in FIG. 2. As shown in FIG. 2, some of the gaps caused by the microscopic irregularities of the first bonded surface 1A and the second bonded surface 2A may not be filled with resin, forming voids 5.

[0017] The mass per unit area of ​​the cured thermosetting resin constituting the thermal interface bonding member 3 is preferably 0.01 mg / cm 2 More than 1.5mg / cm 2 The mass of the cured thermosetting resin per unit area is 0.01 mg / cm or less. 2 More than 1.5mg / cm 2 Within the following range, the micro-irregularities on the first and second bonded surfaces 1A and 2A allow the first and second bonded members 1 and 2 to maintain contact with each other, and the cured thermosetting resin fills in the gaps between the micro-irregularities on the first and second bonded surfaces 1A and 2A, ensuring contact between the first and second bonded members 1 and 2. 2If the mass per unit area is less than 1.5 mg / cm, the number of voids 5 increases, which makes it easier for poor bonding to occur, and the thermal conductivity is easily reduced due to the influence of the voids 5 having high thermal resistance, which is undesirable. 2 If the mass per unit area of ​​the cured thermosetting resin exceeds 0.02 mg / cm, the area where the first member 1 and the second member 2 are in direct contact with each other and have low thermal resistance will decrease, which is undesirable as the thermal conductivity will tend to decrease. 2 More than 1.0mg / cm 2 More preferably, it is 0.03 mg / cm or less. 2 More than 0.45mg / cm 2 or less, and the thermal conductivity can be further increased.

[0018] The average thickness of the cured thermosetting resin constituting the thermal interface bonding member 3 (hereinafter also referred to as the "average thickness of the thermosetting resin") is preferably 0.1 μm or more and 15.0 μm or less. When the average thickness of the thermosetting resin is within the range of 0.1 μm or more and 15.0 μm or less, as described above, the cured thermosetting resin fills in the microscopic irregularities of the first and second bonded surfaces 1A and 2A while ensuring contact between the first and second bonded members 1 and 2, thereby achieving good thermal conductivity. The average thickness of the thermosetting resin is more preferably 0.2 μm or more and 8 μm or less, and even more preferably 0.3 μm or more and 4 μm or less, which further enhances thermal conductivity.

[0019] The value obtained by dividing the average thickness of the thermosetting resin by the arithmetic mean surface roughness Ra of the first and second bonded surfaces 1A and 2A is preferably 0.3 to 10.0. When the average thickness of the thermosetting resin is in the range of Ra to 10 times Ra, as described above, the cured thermosetting resin fills in the microscopic irregularities of the first and second bonded surfaces 1A and 2A while ensuring contact between the first and second bonded members 1 and 2, thereby achieving good thermal conductivity. The value obtained by dividing the average thickness of the thermosetting resin by the arithmetic mean surface roughness Ra of the first and second bonded surfaces 1A and 2A is more preferably 0.5 to 5.0, and even more preferably 1.0 to 3.0, which further enhances thermal conductivity.

[0020] The first and second members 1 and 2 to be bonded by the thermal interface bonding member 3 of this embodiment are made of, for example, Cu. Materials other than Cu include metals such as Ag, Al, and Fe; alloys such as SUS and CuMo alloys; carbon (C)-based materials such as graphite; ceramics such as Al2O3, SiO2, SiC, Si3N4, AlN, and BN; composite materials such as AlCSi; and combinations thereof. The materials constituting the first and second members 1 and 2 may be the same or different. Materials used in semiconductor packages or heat sinks, or heat spreaders for semiconductor power devices, are preferred for the first and second members 1 and 2. At least one of the first and second members 1 and 2 may be a heat generating element such as an integrated circuit (IC) chip.

[0021] The thermal interface bonding member 3 of this embodiment does not contain fillers or carbon nanotubes, unlike conventional techniques, and therefore the gap between the surfaces to be bonded can be made almost zero, allowing the bonded members to come into direct contact with each other. Furthermore, the thermal resistance of the resin itself is lower than when a thermoplastic resin is used, improving thermal conductivity. When the bonded members are devices made of conductive materials, electrical resistance can also be reduced, and bonding strength can be ensured by adjusting the amount of resin. The thermal interface bonding member 3 of this embodiment can be manufactured using a simple manufacturing method, as described below, and can improve thermal conductivity.

[0022] When the first member to be joined 1 shown in FIG. 1 is a heat generating element such as an IC chip, and the second member to be joined 2 is a heat dissipating element such as a heat sink, the thermal interface joining member 3 can efficiently transfer heat from the first member to be joined 1 as a heat generating element to the second member to be joined 2 as a heat dissipating element.

[0023] 2. Manufacturing method FIG. 3 is a schematic diagram illustrating a manufacturing method of a thermal interface bonding member 3 according to this embodiment. The thermal interface bonding member 3 according to this embodiment is manufactured by a heat press process in which a thermosetting resin monomer is polymerized and cured. For example, a solution containing a thermosetting resin monomer and a solvent is used, and the solvent is volatilized in the heat press process to polymerize and cure the thermosetting resin monomer. For example, as shown in 301 of FIG. 3 , a solution 3A containing a thermosetting resin monomer and a solvent is first dripped onto a first surface 1A of a first member 1 to be bonded. Next, as shown in 302 of FIG. 3 , a second member 2 to be bonded is placed on the first member 1 via the solution 3A, with the second surface 2A of the second member 2 facing the first surface 1A. Next, as shown in 303 of FIG. 3, a heat pressing process is performed in which the first member to be joined 1 and the second member to be joined 2 are pressed with a predetermined pressure in the direction in which they approach each other as indicated by the arrow 6, and then heated. This volatilizes the solvent, polymerizes and hardens the thermosetting resin monomer, and forms a thermal interface bonding member 3 made of a hardened thermosetting resin.

[0024] The thermosetting resin monomer contained in the solution 3A is the above-mentioned thermosetting resin monomer, and may be any monomer that becomes a cured product of the thermosetting resin by the above-mentioned heat pressing step.

[0025] The solvent contained in Solution 3A is not particularly limited, and is a solvent suitable for dissolving thermosetting resin monomers, such as alcohol solvents such as methanol and ethanol, ether solvents such as diethyl ether and ethyl propyl ether, amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide, ketone solvents such as acetone and diethyl ketone, aromatic nonpolar solvents such as benzene and toluene, and lactone solvents such as γ-caprolactone and γ-valerolactone.

[0026] Instead of the solution 3A containing the thermosetting resin monomer and a solvent, a solvent-free melt of the thermosetting resin monomer can be used. The monomer is thermally cured in a liquid state while being uniformly spread between the first member 1 and the second member 2 to be joined, thereby forming a thermal interface bonding member 3 with excellent thermal conductivity. Note that a low viscosity of the monomer solution 3A or melt is preferable because it allows the formation of a thermal interface bonding member 3 with fewer voids 5.

[0027] Solution 3A may further contain additives such as a polymerization initiator such as a thermal polymerization initiator, a phenolic curing agent such as a phenol novolac resin or a cresol novolac resin, or a curing accelerator such as imidazole or piperidine.

[0028] The amount of solution 3A containing a monomer of a thermosetting resin and a solvent supplied to the first bonded surface 1A is set so that the mass per unit area of ​​the cured thermosetting resin formed after the above-mentioned heat pressing step is 0.2 mg / cm. 2 More than 1.5mg / cm 2 Even if the solution 3A containing the thermosetting resin monomer and solvent is supplied in excess, the resin is extruded from between the first bonded surface 1A and the second bonded surface 2A in the above-mentioned heat pressing step. Therefore, the supply amount of the solution 3A is preferably 3.0 mg / cm. 2 It is preferable that:

[0029] In the heat pressing step of volatilizing the solvent and polymerizing and curing the thermosetting resin monomer, for example, heat pressing is performed to cure the thermosetting resin. The heat pressing is performed at a temperature at which the thermosetting resin monomer is polymerized and cured, and is not particularly limited, and depends on the type of thermosetting resin monomer, but is, for example, 100°C or higher and 260°C or lower. The heat pressing is performed for a time sufficient for curing, and is not particularly limited, and depends on the type of thermosetting resin monomer, but is, for example, 10 minutes to 10 hours.

[0030] In the heat-pressing process, preferably, heating is performed at a first temperature (first step), followed by heating and pressing at a second temperature equal to or higher than the melting point of the thermosetting resin monomer (second step), and then heating and pressing at a third temperature equal to or higher than the curing temperature of the thermosetting resin (third step). In the heat-pressing process including the first to third steps, the second temperature is higher than the first temperature, and the third temperature is higher than the second temperature. Depending on the types of thermosetting resin monomer and solvent, the first, second, and third temperatures can be set within the following ranges, for example: The first temperature is a temperature equal to or higher than the boiling point of the solvent, for example, 56°C to 80°C. The second temperature is a temperature equal to or higher than the melting point of the thermosetting resin monomer, for example, 80°C to 120°C. The third temperature is a temperature equal to or higher than the curing temperature of the thermosetting resin, for example, 120°C to 260°C. Heating in the heat pressing step is carried out, for example, by pressing a heater against one or both of the first member to be joined 1 and the second member to be joined 2, heating the first member to be joined 1 and / or the second member to be joined 2 by heating the heater, and conducting the heat to the solution 3A containing the thermosetting resin monomer through the first member to be joined 1 and the second member to be joined 2. Alternatively, a preheated heater or heat bath may be pressed against the second member to be joined 2, or the first member to be joined 1 may be placed on a preheated heater or heat bath, or further heating may be performed in an atmosphere at a predetermined temperature.

[0031] In the first step at a first temperature, the solvent is removed (dried) at a temperature above the boiling point of the solvent. This prevents voids 5 from forming after curing due to bubbles caused by evaporation of the solvent. The first step is performed for, for example, 10 seconds to 20 minutes. In the second step at a second temperature, the temperature is set to a temperature above the melting point of the monomer of the thermosetting resin, allowing the monomer to melt and penetrate into the gaps between the first bonded surface 1A and the second bonded surface 2A. The second step is performed for, for example, 10 seconds to 20 minutes. In the third step at a third temperature, the temperature is set to a temperature above the curing temperature of the thermosetting resin, and the resin is cured. The third step is performed for, for example, 1 minute to 3 hours. In the heat pressing process including the first to third steps described above, before heating to the heat curing temperature, the temperature is held at or above the boiling point of the solvent for a predetermined time to prevent bubbles from being generated due to the boiling of the solvent during heat curing, and by holding the temperature at or above the melting point of the monomer for a predetermined time, the monomer is uniformly distributed so that it conforms to the unevenness of the joined members, thereby reducing the voids 5 in the cured thermosetting resin after heat curing and increasing thermal conductivity.

[0032] In the second and third steps of the heat pressing, the heat pressing pressure is preferably 0.8 MPa or higher. Increasing the pressure increases the contact area between the bonded members made of Cu or the like, thereby reducing thermal resistance. A heat pressing pressure of 10 MPa or higher is even more preferable. Furthermore, a heat pressing pressure of 40 MPa or lower is preferable. A heat pressing pressure of more than 40 MPa is undesirable because, if the bonded members are devices, the device may be damaged and the effect of reducing thermal resistance is small. The pressure application in the heat pressing process can be performed by, for example, a method of fixing the first bonded member 1 and pressing the second bonded member 2, a method of fixing the second bonded member 2 and pressing the first bonded member 1, or a method of pressing both the first bonded member 1 and the second bonded member 2, but is not particularly limited.

[0033] FIG. 4 shows an example of a temperature profile for a three-step heat-pressing process, including first to third steps. Here, the first temperature is 60°C, the second temperature is 100°C, and the third temperature is 180°C. No pressure is applied in the first step, and the pressure applied in the second and third steps is 10 MPa. In the heat-pressing process shown in FIG. 4, a second member to be joined 2 is placed on a first member to be joined 1 via a solution 3A containing a thermosetting resin monomer and a solvent. The first member is then heated to a first temperature (60°C) from time T0 to time T1. The first temperature (60°C) is then maintained for, for example, 5 minutes from time T1 to time T2 (first step). At time T2, pressure application at 10 MPa begins, and the temperature is increased from the first temperature (60°C) to a second temperature (100°C) from time T2 to time T3. Next, the second temperature (100°C) is maintained for, for example, 10 minutes from time T3 to time T4 (second step). Next, the temperature is increased from the second temperature (100°C) to a third temperature (180°C) from time T4 to time T5. Next, the third temperature (180°C) is maintained for, for example, 90 minutes from time T5 to time T6 (third step). Next, the pressure is released at time T6, and the temperature is decreased from the third temperature (180°C).

[0034] When a solvent-free melt of a thermosetting resin monomer is used instead of the solution 3A containing the thermosetting resin monomer and the solvent, the temperature profile can be such that the first step of maintaining the temperature at 60°C for 5 minutes is omitted from the three-step heat pressing shown in FIG. 4 .

[0035] 3. Action and Effects The thermal interface bonding member 3 of this embodiment is made of only a thermosetting resin and is formed by filling in the gaps of the micro-irregularities on the first bonded surface 1A and the second bonded surface 2A so that the first bonded member 1 and the second bonded member 2 come into contact with each other.

[0036] The thermal interface bonding member 3 of this embodiment, unlike conventional techniques, does not contain fillers or carbon nanotubes, so the gap between the surfaces to be bonded can be made nearly zero, allowing the bonded members to come into direct contact with each other. Furthermore, the thermal resistance of the resin itself is lower than when a thermoplastic resin is used, improving thermal conductivity. When the bonded members are devices made of conductive materials, electrical resistance can also be reduced, and bonding strength can be ensured by adjusting the amount of resin. The thermal interface bonding member 3 of this embodiment does not require complex processes such as forming carbon nanotubes, making the manufacturing method simple and improving thermal conductivity.

[0037] According to the manufacturing method of the thermal interface bonding member 3 of this embodiment, by bonding using a heat press, it is possible to make the gap between the bonding surfaces almost zero, and to increase the contact area between the bonded members made of Cu or the like, thereby reducing the thermal resistance.

[0038] 4. First Example As a first example, the results of testing the change in thermal resistance with heating temperature are shown for Example 1, which uses a thermosetting resin monomer, Comparative Example 1, which uses vertically aligned carbon nanotubes (CNTs) and a thermoplastic resin, and Comparative Example 2, which uses CNTs and a thermosetting resin monomer.

[0039] <Method for measuring thermal resistance> Thermal resistance was measured using a steady-state method. Figure 5 is a schematic diagram of the sample for measuring thermal resistance. As shown in Figure 5, samples were prepared in which a thermal interface bonding member 13 was sandwiched between the bonding surfaces (first bonding surface 11A, second bonding surface 12A) of two Cu blocks (first bonding member 11, second bonding member 12) arranged above and below each other, and thermal resistance was measured. For each sample, the upper Cu block was heated to a predetermined temperature using a heater while applying a predetermined pressure, and the lower Cu block was cooled using a chiller. A heat flux q was applied perpendicular to the surface of the sample, and the sample was left to stand until it reached a steady state. The temperatures of the upper and lower Cu blocks in the steady state were measured using a radiation thermometer. From the temperature profile of the Cu block, the temperatures at the end points of the Cu block, i.e., the temperatures at the end points of the sample, were extrapolated to determine the temperature difference ΔT. The temperature difference ΔT was then divided by the heat flux q to obtain the thermal resistance R. therm The thermal resistance R therm The heat flux q used in the calculation is the average value of the heat fluxes of the upper and lower Cu blocks.

[0040] <Measurement of thermal resistance during temperature cycle heating> In Example 1, a thermosetting resin solution was dropped onto a first surface of a first member made of a Cu block, and a second member made of a Cu block was placed on the first member with the thermosetting resin solution interposed between them, with the second surface facing the first surface. The second member was then heated in a temperature cycle of repeated temperature increases and decreases by adjusting the voltage input to the heater, and thermal resistance was measured under a pressure of 0.8 MPa. The temperature cycle was room temperature → 45°C → room temperature → 72°C → room temperature → 95°C → room temperature → 120°C → room temperature → 153°C → room temperature → 172°C → room temperature.

[0041] The thermosetting resin solution used was E1 resin monomer (ENEOS Corporation) containing epoxy resin monomer (Celloxide 2021P, Daicel Corporation), phenolic resin monomer (Bisphenol F, Honshu Chemical Industry Co., Ltd.), and benzoxazine (Pd-type benzoxazine, Shikoku Chemical Industry Co., Ltd.) in a mass ratio of 1:0.4:4, with acetone as the solvent. The concentration of the mixture in the solution was 4.3 vol%. The amount of thermosetting resin solution supplied to the first bonded surface was 40 to 60 μL, and it was applied by spin coating. The applied amount was 60 μL, and the resin monomer concentration and the area of ​​the bonded surface of the Cu block were 1.0 cm. 2 , the density of thermosetting resin is 1.1 g / cm 3 From this, the mass of resin per unit area supplied to the first bonded surface is calculated to be 2.85 mg / cm 2 When applying by spin coating, part of the supplied thermosetting resin solution is blown away from the first surface to be joined by centrifugal force. Also, part of the thermosetting resin solution supplied to the first surface to be joined is pushed out from between the first and second surfaces to be joined. Therefore, the mass of resin per unit area between the first and second surfaces to be joined is 2.85 mg / cm. 2 It's getting smaller.

[0042] In Comparative Example 1, vertically aligned CNTs synthesized on a substrate were impregnated with a thermoplastic resin solution by spin coating. The vertically aligned CNTs were then pressed against the first surface of a first bonded member made of a Cu block and heated to 110°C to remove the solvent and transfer the vertically aligned CNT / thermoplastic resin composite. The second bonded member, made of a Cu block, was then placed on the first bonded member with the vertically aligned CNT / thermoplastic resin composite interposed between them, with the second bonded member facing the first bonded member. The second bonded member was then heated in a temperature cycle of repeated heating and cooling, and thermal resistance was measured under a pressure of 0.8 MPa. The temperature cycle was room temperature → 50°C → room temperature → 64°C → room temperature → 76°C → room temperature → 99°C → room temperature → 130°C → room temperature → 156°C → room temperature.

[0043] The thermoplastic resin solution used was a resin solution (manufactured by JSR Corporation) containing a styrene-isoprene copolymer as the thermoplastic resin and toluene as the solvent, with a concentration of 7.2 vol %.

[0044] In Comparative Example 2, the thermosetting resin solution used in Example 1 was used instead of the thermoplastic resin solution of Comparative Example 1, and the solution was heated in a temperature cycle of repeated temperature increases and decreases, and the thermal resistance was measured under a pressure of 0.8 MPa. The temperature cycle was room temperature → 45°C → room temperature → 56°C → room temperature → 93°C → room temperature → 119°C → room temperature → 143°C → room temperature → 168°C → room temperature.

[0045] Fig. 6 shows a graph showing the change in thermal resistance with respect to the heating temperature in the first example. 601 in Fig. 6 is the graph for Comparative Example 1. As the heating temperature increases, the thermal resistance decreases, and after heating at 156°C, the thermal resistance decreased by 57 mm. 2 It was confirmed that the thermal resistance was reduced to 1000 K / W and that the thermal resistance was maintained even when the temperature was returned to room temperature.

[0046] 6 is a graph of Comparative Example 2. As the heating temperature increases, the thermal resistance decreases. After heating at 168°C, the 2 It was confirmed that the thermal resistance was reduced to 1000 K / W and that the thermal resistance was maintained even when the temperature was returned to room temperature.

[0047] 603 in Figure 6 is a graph of Example 1. Before the temperature cycle, the thermal resistance was 180 mm 2 K / W, but as the heating temperature increases, the thermal resistance decreases rapidly, and after heating at 172°C, the 2 It was confirmed that the thermal resistance was reduced to 172°C / W, and that the thermal resistance was maintained even when the temperature was returned to room temperature. The thermal resistance value after heating at 172°C for Example 1, which used a thermosetting resin, was smaller than the thermal resistance of Comparative Example 2, which used the same thermosetting resin and CNT. Unlike Comparative Example 2, Example 1 does not contain CNT, so the gap between the joined surfaces can be made almost zero, and the joined members come into direct contact with each other.

[0048] 5. Second Example As a second example, the results of measuring the thermal resistance of Example 2, a thermal interface bonding member made of a cured product of a thermosetting resin, and Comparative Example 3, a thermal interface bonding member made of a thermoplastic resin, are shown.

[0049] <Manufacturing of thermal interface bonding materials> The thermal interface bonding member of Example 2 was manufactured as follows. A thermosetting resin solution to be used as the thermal interface bonding member was dropped onto the first bonding surface of a first bonding member made of a Cu block. The second bonding member made of a Cu block was then placed on the first bonding member with the thermosetting resin solution interposed between them, with the second bonding surface of the second bonding member facing the first bonding surface. The resin was then cured by heat pressing for 90 minutes at a temperature of 180°C under a pressure of 0.8 MPa. The same thermosetting resin solution as in Example 1 was used, and the amount supplied to the first bonding surface was 20 μL. The amount of thermosetting resin solution supplied, the concentration of the resin monomer, and the area of ​​the bonding surface of the Cu block (1.0 cm2) were all determined. 2 , the density of thermosetting resin is 1.1 g / cm 3 The mass of resin per unit area is calculated as 0.95 mg / cm 2 It is calculated as follows.

[0050] A thermal interface bonding member of Comparative Example 3 was manufactured as follows. Similar to Example 2, the thermoplastic resin solution used in Comparative Example 1 was used instead of the thermosetting resin solution, and heat pressing was performed for 90 minutes at a temperature of 80°C under a pressure of 0.8 MPa. The amount of thermoplastic resin solution supplied to the first bonding surface was 14 μL. The amount of thermoplastic resin solution supplied, the resin concentration, and the area of ​​the bonding surface of the Cu block (1.0 cm2) were all determined. 2 , density of thermoplastic resin is 0.92g / cm 3 The mass of resin per unit area is calculated as 0.93 mg / cm 2 It is calculated as follows.

[0051] FIG. 7 is a diagram showing the measurement results of the thermal resistance evaluation according to the second example. 701 in FIG. 7 is a diagram showing the evaluation results of the thermal resistance of the thermal interface bonding member of Comparative Example 3. The horizontal axis indicates the vertical position of the structure in which the second bonded member / thermal interface bonding member / first bonded member are stacked, and the vertical axis indicates the temperature. In Comparative Example 3, the thermal resistance graph shows two straight line segments with a predetermined slope and a central steep slope portion connecting the two straight line segments. The magnitude of the temperature difference in the steep central portion corresponds to the magnitude of the thermal resistance of the thermal interface bonding member. The magnitude of the thermal resistance is 80.3 mm 2 It was K / W.

[0052] 702 in Fig. 7 shows the evaluation results of the thermal resistance of the thermal interface bonding member of Example 2. In Example 2, the temperature difference in the central part connecting the two straight line parts is smaller than that in Comparative Example 3, and it was confirmed that the thermal resistance is smaller. The magnitude of the thermal resistance is 3.5 mm 2 It was K / W.

[0053] FIG. 8 shows the results of measuring the thermal resistance of three samples of Example 2 and two samples of Comparative Example 3. In FIG. 8, TSR indicates the thermal resistance of Example 2, and TPE indicates the thermal resistance of Comparative Example 3. As shown in FIG. 8, in Comparative Example 3, the thermal resistance of two samples was about 80 mm 2 K / W and approximately 120mm 2 In contrast, in Example 2, the thermal resistance of the three samples was approximately 3.5 to approximately 20 mm 2 It was confirmed that the thermal resistance was a small value of 1000 kJ / W, and that there was little variation. This is thought to be due to the fact that the thermal resistance of the thermosetting resin itself is smaller than the thermal resistance of the thermoplastic resin itself. In addition, in Example 2, the thermal resistance was reduced and the variation in thermal resistance between samples was also reduced due to the effect of maintaining and fixing the joined parts in direct contact with each other during the polymerization and hardening process of the thermosetting resin monomer.

[0054] 6. Third Example In the third example, the amount of resin solution dropped was changed to produce thermal interface bonding members made of a cured product of a thermosetting resin, and the thermal resistance and adhesiveness were evaluated.

[0055] <Production of Thermal Interface Bonding Members of Samples 1 to 7> The thermal interface bonding member of Sample 1 was manufactured as follows. A thermosetting resin solution for the thermal interface bonding member was dropped onto the first bonding surface of a first bonding member made of a Cu block. A second bonding member made of a Cu block was placed on the first bonding member with the thermosetting resin solution interposed between them, with the second bonding surface of the second bonding member facing the first bonding surface. A heat press process was performed using the three-step temperature profile shown in Figure 4 and a pressure of 10 MPa in the second and third steps to harden the resin. The thermosetting resin solution used was 2.5 μL of a resin solution prepared by adjusting the concentration of E1 resin monomer (manufactured by ENEOS Corporation) described in Example 1 with acetone to a concentration of 5.4 vol%. The amount of thermosetting resin solution supplied, the concentration of the resin monomer, and the area of ​​the bonding surface of the Cu block (1.0 cm2) were all determined. 2 , the density of thermosetting resin is 1.1 g / cm 3 From this, the mass of resin dropped per unit area (calculated supply amount of resin [mg / cm 2 ]) is calculated to be 0.15 mg / cm 2 It is calculated as follows.

[0056] Samples 2 to 7 were produced in the same manner as Sample 1, except that resin solutions having the concentrations shown in Table 1 were dripped in the volumes shown in Table 1. Table 1 also shows the mass of resin dripped per unit area (calculated amount of resin supplied), calculated in the same manner as Sample 1.

[0057] [Table 1]

[0058] <Evaluation of Adhesion> The adhesiveness of the resulting thermal interface bonding members of Samples 1 to 7 to the bonded members was examined. The results are shown in Table 1. Under each sample condition, the number of thermal interface bonding members that showed good adhesion out of the total number of members produced is shown in Table 1 as a fraction. In Sample 1, bonding failure occurred, and in all three of the three members, the first bonded member and the second bonded member could not be bonded. In Samples 2 to 7, the adhesiveness was good. The cured thermosetting resin filled in the gaps of the micro-irregularities between the first bonded surface of the first bonded member and the second bonded surface of the second bonded member, and hardened, maintaining the bonded state between the first bonded member and the second bonded member. A 0.15 mg / cm 2 It was confirmed that a larger amount of resin was required.

[0059] <Evaluation of thermal resistance> The thermal resistance of the obtained thermal interface bonding members of Samples 2 to 5 was measured. The results are shown in Table 1. The calculated amount of resin supplied was 0.30 mg / cm 2 In sample 2, the thermal resistance was measured for three thermal interface bonding materials, and the values ​​were 18.7 to 44.6 mm. 2 The thermal resistance of samples 3 to 5 was measured using one thermal interface bonding material each, and the thermal resistance was 15 to 17 mm. 2 A low thermal resistance of 0.6 mg / cm was obtained. The calculated resin supply amount for sample 3 was 0.6 mg / cm 2 The calculated resin supply amount for Sample 4 was 1.2 mg / cm 2 The calculated resin supply amount for sample 5 was 2.4 mg / cm 2 Although the amount of resin supplied is significantly different between the first and second joined members, the resin is pushed out by the pressure applied in the heat pressing process, and the mass of resin per unit area between the first and second joined members becomes approximately the same, which is thought to have resulted in similar thermal resistance.

[0060] <Evaluation of electrical resistance> The electrical resistance of the thermal interface bonding members obtained in Samples 2 to 7 was examined. The electrical resistance was measured with a tester, and those that showed a resistance value of 0 Ω were determined to be electrically connected, and are indicated by "O" in Table 1. Samples 2 to 7 had an electrical resistance of 0 Ω, confirming that the first bonded member and the second bonded member were not insulated from each other by the thermal interface bonding member made of a cured thermosetting resin.

[0061] <Production of Thermal Interface Bonding Members of Samples 8 to 12> Similar to Sample 7, 20 μL of a resin solution with a resin monomer concentration of 43 vol% was used, and three stages of heat pressing were performed to produce thermal interface bonding members for Samples 8 to 10. The calculated resin supply amount for Samples 8 to 10 was 9.5 mg / cm 2 It is calculated as follows.

[0062] Similar to Samples 8 to 10, thermal interface bonding members of Samples 11 and 12 were manufactured by two-stage heat pressing using 20 μL of a resin solution with a resin monomer concentration of 43 vol%. The two-stage heat pressing has a temperature profile that omits the first step, in which a temperature of 60°C is maintained for 5 minutes, compared to the three-stage heat pressing shown in FIG. 4, and the pressure conditions in the second and third steps are 10 MPa, the same as the heat pressing in FIG. 4. The calculated resin supply amount for Samples 11 to 12 was 9.5 mg / cm. 2 It is calculated as follows.

[0063] Similar to Samples 8 to 10, a thermal interface bonding member of Sample 13 was manufactured by performing a heat treatment without pressure using 20 μL of a resin solution with a resin monomer concentration of 43 vol%. The heat treatment without pressure was performed in the same manner as the three-stage temperature profile shown in FIG. 4, except that no pressure was applied.

[0064] [Table 2]

[0065] <Evaluation of thermal resistance> The thermal resistance of the thermal interface bonding members of Samples 8 to 13 was measured. The results are shown in Table 2. Samples 8 to 10, which were manufactured by three-stage hot pressing, had a thermal resistance of 0.6 mm. 2 K / W~11.1mm 2 K / W and 20mm 2 A low thermal resistance of less than 1000 K / W was obtained. Samples 11 and 12, which were manufactured by two-stage hot pressing, had a thermal resistance of 0.1 mm. 2 Low values ​​of K / W and 65mm 2 The thermal resistance was a high value of 51.3 mm / W, and there was a large variation. In the two-stage heat press, the first step of maintaining the temperature at 60°C was omitted, so the thermal resistance may not decrease due to the influence of voids caused by bubbles due to evaporation of the solvent in the resin solution, which is thought to be why the thermal resistance varied between samples. Sample 13, which was produced by heat treatment without pressure, had a thermal resistance of 51.3 mm / W. 2 The thermal resistance was as high as 1000kJ / W.

[0066] <Measurement of the average thickness of thermosetting resin> The average thickness of the thermosetting resin in the obtained samples 8 to 13 was measured. The results are shown in Table 2. To determine the average thickness of the thermosetting resin, the second bonded member was peeled off from the first bonded member in each of the thermal interface bonding members of samples 8 to 13, and the surface of the first bonded surface of the first bonded member, on which some of the cured thermosetting resin remained in island-like shapes, was observed with a white light confocal microscope (manufactured by Lasertec Corporation). The actual average thickness was determined from the difference between the average height of the surface of the layer of cured thermosetting resin and the average height of the first bonded surface. The measurement limit for the actual average thickness is approximately 1.0 μm.

[0067] <Calculating the resin mass per unit area from the measured average thickness> The resin amount per unit area (mass of resin per unit area) of Samples 8 to 13 was calculated from the measured average thickness of the thermosetting resin obtained above. The results are shown in Table 2. The calculation of the resin amount from the measured average thickness was performed using the density of the thermosetting resin, 1.1 g / cm. 3 was calculated using

[0068] <Calculation of the value obtained by dividing the measured average thickness by the arithmetic average surface roughness Ra of the bonded surfaces> The arithmetic mean roughness Ra of the first bonded surface of the first bonded member and the second bonded surface of the second bonded member of the Cu block used in Example 3 was 1.25 μm. The measured mean thickness was divided by 1.25 to calculate the arithmetic mean surface roughness Ra of the bonded surfaces. The results are shown in Table 2.

[0069] In Samples 8 to 10, the measured average thickness of the cured thermosetting resin was small, ranging from 1.3 μm to 1.4 μm, and the variation was small. The calculated mass of resin per unit area was also 0.14 mg / cm. 2 ~0.15mg / cm 2 The values ​​obtained by dividing the measured average thickness by Ra were also small, ranging from 1.04 to 1.12, and the variation was also small. These small values ​​and small variations correspond to low thermal resistance values ​​and small variations.

[0070] For Samples 11 and 12, which were manufactured using a two-stage hot press, the measured average thickness of Sample 11 was less than 1.0 μm, which is below the measurement limit, and the calculated mass of resin per unit area was 0.11 mg / cm 2 The measured average thickness was less than 0.80, and the value obtained by dividing the measured average thickness by Ra was small, corresponding to low thermal resistance. However, in sample 12, the measured average thickness was 8.5 μm, which was thick, and the calculated mass of resin per unit area was 0.94 mg / cm. 2 The value obtained by dividing the measured average thickness by Ra is 6.80, which is large and corresponds to a high thermal resistance.

[0071] For sample 13, which was produced by heat treatment without pressure, the measured average thickness was 4.1 μm, and the calculated resin mass per unit area was 0.45 mg / cm 2 The measured average thickness divided by Ra was 3.28, which corresponds to a high thermal resistance. It is thought that because no pressure was applied, less resin was extruded from between the first and second bonded surfaces, resulting in a thicker measured average thickness and higher thermal resistance. [Explanation of symbols]

[0072] 1, 11 First member to be joined 1A, 11A 1st surface to be joined 2, 12 Second member to be joined 2A, 12A 2nd surface to be joined 3, 13 Thermal interface bonding materials 3A Solution containing thermosetting resin monomer and solvent 5 void

Claims

1. A thermal interface bonding material made of a cured thermosetting resin.

2. This process involves a heat press process that polymerizes and hardens the thermosetting resin monomer. A method for manufacturing a thermal interface bonding member made of a cured product of a thermosetting resin.

3. The heat pressing step includes: a first step of heating at a first temperature; a second step of applying pressure while heating at a second temperature equal to or higher than the melting point of the monomer of the thermosetting resin after the first step; a third step of applying pressure while heating at a third temperature equal to or higher than the curing temperature of the thermosetting resin after the second step, The second temperature is higher than the first temperature, and the third temperature is higher than the second temperature. The method for manufacturing the thermal interface bonding member according to claim 2 .

4. The heat pressing step involves dropping a solution containing a monomer of the thermosetting resin and a solvent onto the joining interface of a first member to be joined, placing a second member to be joined to the first member to be joined via the solution, and heating the first member to be joined while pressing the second member to the first member to the second member in a direction that brings them closer to each other. The method for manufacturing the thermal interface bonding member according to claim 2 or 3.

5. The heat pressing step is performed at a pressure of 10 MPa or more. The method for manufacturing the thermal interface bonding member according to claim 2 .

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