Thermally conductive transfer tape, method for manufacturing same, coating film transfer tool, and method for mounting electronic component

Abstract

A thermally conductive transfer tape 1 of the present invention includes a release sheet layer 3 and a thermally conductive sheet layer 2 atop the release sheet layer. The thermally conductive sheet layer 2 includes a matrix resin and a thermally conductive filler. The thermally conductive sheet layer 2 is peeled from the release sheet layer 3 to enable pressure transfer. The thermally conductive transfer tape 1 is loaded onto a winding core in a coating film transfer tool by being wound around the winding core, and the side of the thermally conductive sheet layer 2 is pressure-transferred to a transfer surface. The following are provided: the thermally conductive transfer tape, which, due to the foregoing configuration, can be continuously transferred without dripping; a method for manufacturing the same; the coating film transfer tool; and a method for mounting an electronic component.

Description

Thermally conductive transfer tape, its manufacturing method, coating film transfer tool, and electronic component mounting method

[0001] The present invention relates to a thermally conductive transfer tape suitable for being interposed between a heat-generating portion of an electric or electronic component or the like and a heat sink, a method for producing the same, a coating film transfer tool, and a method for mounting electronic components.

[0002] In recent years, the performance of semiconductors such as CPUs has improved dramatically, resulting in enormous increases in heat generation. Therefore, heat-generating electronic components are equipped with heat sinks, and liquid thermally conductive compositions such as thermally conductive grease or thermally conductive sheets are used to improve adhesion between the semiconductor and the heat sink. For example, when interposing a liquid thermally conductive composition between a heat generating element and a heat sink, a method of applying the composition using a syringe filled with the liquid thermally conductive composition is available, allowing for continuous application. Patent Document 1 proposes a thermally conductive silicone grease containing a specific cyclic organopolysiloxane and crosslinked. Patent Document 2 proposes a thermally conductive silicone grease crosslinked using hydrosilylation catalyst microparticles with a microcapsule structure. Patent Document 3 proposes a thermally conductive silicone grease crosslinked using an organohydrogenpolysiloxane having two or more hydrogen atoms bonded to silicon atoms per molecule.

[0003] JP 2023-026788 A JP 2021-147591 A JP 2021-098804 A

[0004] However, when the liquid thermally conductive composition is sandwiched between a heat generating element and a heat dissipating element, the composition tends to drip from between the heat generating element and the heat dissipating element.

[0005] In order to solve the above-mentioned problems of the prior art, the present invention provides a thermally conductive transfer tape that is non-dripping and allows continuous transfer, a manufacturing method thereof, a coating film transfer tool, and a method for mounting electronic components.

[0006] The first embodiment of the present invention relates to a thermally conductive transfer tape comprising a release sheet layer and a thermally conductive sheet layer thereon, wherein the thermally conductive sheet layer comprises a matrix resin and a thermally conductive filler, and the thermally conductive sheet layer can be peeled from the release sheet layer and transferred under pressure.

[0007] A second embodiment of the present invention relates to a method for producing the thermally conductive transfer tape, which includes the steps of kneading a material containing a matrix resin and a thermally conductive filler to form a compound, rolling the compound to produce a thermally conductive transfer tape of a predetermined thickness, and laminating a release sheet to one side of the thermally conductive transfer tape.A third embodiment of the present invention relates to a method for producing the thermally conductive transfer tape, which includes the steps of kneading a material containing a matrix resin and a thermally conductive filler to form a compound, dissolving the compound in a solvent and applying it to the surface of a release sheet, and drying the applied coating.

[0008] A fourth embodiment of the present invention relates to a coating film transfer tool including the above-mentioned thermally conductive transfer tape, which includes a means for rotatably storing a payout core and a take-up core within a case, a transfer head equipped with a transfer pressure section protruding from the case, a means for paying out the thermally conductive transfer tape from the payout core and transferring the transfer tape to a surface to be transferred using the transfer pressure section, and a means for winding up a release sheet layer separated from the thermally conductive sheet layer onto the take-up core.

[0009] A fifth embodiment of the present invention relates to a coating film transfer tool including the above-mentioned thermally conductive transfer tape, comprising a means for rotatably storing a payout core within a case, a transfer head having a transfer pressure section protruding from the case, a means for paying out the thermally conductive transfer tape from the payout core, and a means for pressing and transferring the transfer tape onto a surface to be transferred using the transfer pressure section, and a means for cutting both the thermally conductive sheet layer and the release sheet layer.

[0010] A sixth embodiment of the present invention relates to a method for mounting electronic components using the thermally conductive transfer tape, which includes a step of pressing and transferring the thermally conductive transfer tape onto a surface of an electronic component that includes a heat-generating portion, and a step of mounting a heat sink on the surface of the thermally conductive sheet layer.

[0011] The present invention provides a thermally conductive transfer tape that includes a release sheet layer and a thermally conductive sheet layer thereon, the thermally conductive sheet layer containing a matrix resin and a thermally conductive filler, and that can be peeled off from the release sheet layer to perform pressure transfer. This allows for a thermally conductive transfer tape that is free from dripping and allows for continuous transfer, as well as a manufacturing method thereof, a coating film transfer tool, and a method for mounting electronic components. The tape is also suitable as a transfer tape for thermal interface materials (TIMs) that are placed between the heat-generating body and the heat-dissipating body of electronic components such as semiconductors.

[0012] FIG. 1A is a schematic perspective view of a thermally conductive transfer tape according to a first embodiment of the present invention, and FIG. 1B is a cross-sectional view of FIG. 1A. FIG. 2A is a schematic perspective view of a thermally conductive transfer tape according to a second embodiment of the present invention, and FIG. 2B is a cross-sectional view of FIG. 2A. FIG. 3A is a schematic front view of a coating film transfer tool according to a first embodiment of the present invention with the cover removed, FIG. 3B is a schematic perspective view of a transfer head and a bearing unit, FIG. 3C is a cross-sectional view along line I-I in FIG. 3A, and FIG. 3D is a schematic perspective view of a transfer head in which the transfer pressure unit is a roller. FIG. 4A is a schematic front view of a coating film transfer tool 23 according to a second embodiment of the present invention with the cover removed, and FIG. 4B is a partially enlarged view of the tip portion of FIG. 4A. FIG. 5 is a schematic cross-sectional view of a thermally conductive sheet according to an embodiment of the present invention incorporated into a heat dissipation structure.

[0013] The present invention provides a thermally conductive transfer tape comprising a release sheet layer and a thermally conductive sheet layer thereon. The release sheet layer can be, for example, a synthetic resin film such as polyethylene terephthalate coated with a silicone resin, or a paper coated with a silicone resin. The thermally conductive sheet layer comprises a matrix resin and a thermally conductive filler and is required to have thermal conductivity and adhesiveness. Thermal conductivity is required as a thermal interface material (TIM) that transfers heat from heat-generating components such as semiconductors to heat dissipation parts. Adhesiveness is also required for mounting on the surface of the heat-generating component. The thermally conductive sheet layer of the thermally conductive transfer tape of the present invention is releasable from the release sheet layer. This allows the thermally conductive sheet layer to be pressed onto a target surface and the release sheet layer to be peeled off. Furthermore, the pressure during pressure transfer can be a manual pressure when using a handheld coating film transfer tool, and preferably 5 to 100 N / 25 mm when using a large mechanical coating film transfer tool held by a robot arm.

[0014] The thermally conductive sheet layer preferably has a thickness of 20 μm or more and 5 mm or less. In the case of a handheld coating film transfer tool, the thickness is preferably 20 to 500 μm, more preferably 20 to 300 μm, and even more preferably 25 to 200 μm. In the case of a large mechanical coating film transfer tool, the thickness is preferably 20 to 5 mm, more preferably 20 μm to 3 mm, and even more preferably 25 μm to 1 mm. The width of the thermally conductive transfer tape is preferably 1 to 100 mm, more preferably 1 to 80 mm, and even more preferably 1 to 50 mm. This allows the width to be adjusted according to the size of the transferred portion. Furthermore, the length is preferably 1 to 30 m in the case of a handheld coating film transfer tool, but can be any length in the case of a large mechanical coating film transfer tool.

[0015] The matrix resin is preferably a curable silicone resin. Silicone resins have high heat resistance and are unlikely to deteriorate even when applied to heat-generating components such as semiconductors. Silicone polymers will be described as matrix resins. Preferred examples of silicone polymers include addition-curable silicone polymers, peroxide-curable silicone polymers, and condensation-curable silicone polymers. These may be used alone or in combination. As an example, in the case of an addition-reaction silicone composition, a compound having the following composition is preferred. A. Matrix Resin The matrix resin contains the following (A1) and (A2): (A1) Base polymer component: a linear organopolysiloxane containing at least two silicon-bonded alkenyl groups per molecule; (A2) Crosslinking component: an organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms per molecule, in an amount of less than 1 mole per mole of silicon-bonded alkenyl groups in component A;

[0016] In addition to the components (A1) and (A2), the composition may contain an organopolysiloxane that does not have a reactive group. For example, this may be unreacted silicone oil, such as dimethylpolysiloxane. In this specification, the total amount of the organic components, base polymer component (A1), crosslinking component (A2), unreacted silicone oil, and silane coupling agent, is 100 parts by mass. Thermally conductive particles: 100 to 3,000 parts by mass per 100 parts by mass of the organic component. Platinum-based metal catalyst: 0.01 to 1,000 ppm by mass relative to the matrix resin. Other additives: silane coupling agent, cure retarder, colorant, etc.; optional amounts.

[0017] The thermal conductivity of the thermally conductive sheet layer in accordance with ASTM D5470 is preferably 0.8 to 20 W / m K, more preferably 1.2 to 20 W / m K, and even more preferably 1.5 to 20 W / m K. Such a thermal conductivity is suitable for a thermal interface material (TIM).

[0018] A thermally conductive thin film adhesive layer can be further laminated on the surface of the thermally conductive sheet layer. By laminating a thermally conductive thin film adhesive layer, adhesion to the transfer surface can be further improved. It is preferable to fill the adhesive layer with a thermally conductive filler to improve thermal conductivity.

[0019] The thermally conductive sheet layer preferably contains 100 to 3,000 parts by mass of a thermally conductive filler per 100 parts by mass of the organic component. The thermally conductive filler is preferably inorganic particles such as aluminum oxide (alumina), zinc oxide, magnesium oxide, aluminum nitride, boron nitride, aluminum hydroxide, or silicon carbide. These inorganic particles have high thermal conductivity and are suitable as TIMs (Thermal Interface Materials). One type may be used alone, or two or more types may be mixed together. The average particle size of the thermally conductive particles is preferably in the range of 0.01 to 100 μm. The particle size is measured using a laser diffraction / light scattering method, with the 50% mass particle size being measured. This measurement device is the LA-950S2 laser diffraction / scattering particle distribution analyzer manufactured by Horiba, Ltd.

[0020] The first manufacturing method of the thermally conductive transfer tape of the present invention includes the following steps: (1) Compound Preparation Step: Materials containing a matrix resin and a thermally conductive filler are kneaded to form a compound. In this step, heat resistance improvers such as red iron oxide, titanium oxide, and cerium oxide, flame retardants, and flame retardant assistants may be added. Organic or inorganic particle pigments may be added for coloring or toning purposes. Alkoxy group-containing silicone may be added as a material for filler surface treatment. The resulting compound is preferably depressurized to a pressure of -0.08 to -0.1 Pa and left for approximately 5 to 10 minutes to degas. (2) Rolling and Curing Step: The compound is rolled to produce a thermally conductive transfer tape of a predetermined thickness. Rolling can be performed by roll rolling or press working, but roll rolling is preferred because it allows for continuous production. The resulting thermally conductive sheet has a substantially uniform composition from the inside to the outside. A sheet with a uniform composition exhibits uniform physical properties even after being mounted on electrical or electronic components as a TIM. In one example of roll-rolling, the compound is sandwiched between two synthetic resin films and then rolled from above with a roll. The heat-curing conditions for the molded sheet are preferably a temperature of 90 to 120°C and a time of 5 to 180 minutes. In this specification, curing and crosslinking are the same. (3) Bonding Step: A release sheet is bonded to one side of the thermally conductive transfer tape. The tape is then cut to a predetermined width and length to obtain a thermally conductive transfer tape. A second method for manufacturing a thermally conductive transfer tape according to the present invention includes the following steps: (1) Compound Preparation Step: This is the same as the first manufacturing method. (2) Coating Step: The compound is dissolved in a solvent and coated on the surface of a release sheet. Preferred solvents include hexane, toluene, xylene, methyl ethyl ketone, ethyl acetate, and butyl acetate. The viscosity after dissolution in a solvent is preferably 10 to 3,000 mPa·s when measured using a Brookfield viscometer at a temperature of 23°C. (3) Drying Step The applied coating is preferably dried at a temperature of 50 to 160°C for 1 to 10 minutes. The second method for producing a thermally conductive transfer tape of the present invention can form a coating film with a thinner thickness than the first method, for example, a thickness of 100 μm or less after drying.

[0021] The first coating film transfer tool of the present invention includes the following means: (1) Means for rotatably storing a payout core and a take-up core in a case (housing): The payout core is rotatably stored with a thermally conductive transfer tape wound around it. One end of the release sheet layer is fixed to the take-up core, and as the release sheet layer moves, it is taken up onto the take-up core. The case is made of plastic, metal, or the like. (2) Transfer means: A transfer head equipped with a transfer pressure section protrudes from the case, pays out the thermally conductive transfer tape from the payout core, and the transfer pressure section presses and transfers the transfer tape onto the surface to be transferred. (3) Means for winding up the release sheet layer: The release sheet layer separated from the thermally conductive sheet layer is wound up onto the take-up core.

[0022] A second coating film transfer tool of the present invention includes the following means: (1) Means for rotatably storing a payout core in a case (housing): A thermally conductive transfer tape is wound around and rotatably stored on the payout core. (2) Transfer means: A transfer head equipped with a transfer pressure section protrudes from the case, pays out the thermally conductive transfer tape from the payout core, and the transfer pressure section presses and transfers the transfer tape onto a surface to be transferred. (3) Cutting means: Cuts both the thermally conductive sheet layer and the release sheet layer.

[0023] The first and second coating film transfer tools of the present invention may be hand-held types or large mechanical types that are held by a robot arm.

[0024] The electronic component mounting method using the thermally conductive transfer tape of the present invention includes the steps of pressing the thermally conductive transfer tape onto the receiving surface of an electronic component, including a heat-generating element, and mounting a heat sink on the surface of the thermally conductive sheet layer. Supplying the transfer tape to the mounting area of ​​the electronic component and mounting it offers the following advantages: (1) This improves the problem of liquid materials, such as grease, dripping from between the heating element and the heat sink when sandwiched between them. (2) Continuous transfer is possible. (3) The thermally conductive transfer tape is dry, maintaining a clean and dust-free work environment. (4) While sheet-like materials must be cut to a predetermined size (area) in advance and cannot be made to sizes other than the predetermined size, the thermally conductive transfer tape can be supplied to the mounting area of ​​the electronic component in a long form and transferred on the spot to fit the size of the receiving surface. (5) Even if the thermally conductive sheet layer is misaligned or damaged relative to the mounting area of ​​the electronic component, it can be easily corrected by pressing it again. (6) After the second coating film transfer tool presses and transfers the transfer tape onto the surface to be transferred, the thermally conductive sheet layer can be protected with a release sheet layer. The release sheet is peeled off before a heat dissipation member is mounted on the surface of the thermally conductive sheet layer.

[0025] The following description will be made with reference to the drawings. In the following drawings, the same reference numerals indicate the same objects. FIG. 1A is a schematic perspective view of a thermally conductive transfer tape 1 according to one embodiment of the present invention, and FIG. 1B is a cross-sectional view of FIG. 1A. This thermally conductive transfer tape 1 is composed of a thermally conductive sheet layer 2 and a release sheet layer 3. FIG. 2A is a schematic perspective view of a thermally conductive transfer tape 4 according to another embodiment of the present invention, and FIG. 2B is a cross-sectional view of FIG. 2A. This thermally conductive transfer tape 4 is composed of a thermally conductive sheet layer 2, a thermally conductive thin-film adhesive layer 5 on its front surface, and a release sheet layer 3 on its back surface.

[0026] 3A is a schematic front view of a film transfer tool 10 according to a first embodiment of the present invention with its cover removed. This film transfer tool 10 includes a case 13 having two support shafts 11 and 12, a transfer head 14 that protrudes from the left end of the case 13 and has a pressure transfer section 15 at its tip, a payout core 16 and a take-up core 17 rotatably fitted to the support shafts 11 and 12, and a thermally conductive transfer tape 1 having a thermally conductive sheet layer laminated on a release sheet layer. The opening of the pressure transfer section 15 may be covered with a cover (not shown). The thermally conductive transfer tape 1 is wound around the payout core 16, and the transfer tape 1 unwound from the payout core 16 is separated into the release sheet layer and the thermally conductive sheet layer at the pressure transfer section 15. The thermally conductive sheet layer is transferred to the surface to be transferred, and only the release sheet layer is taken up around the take-up core 17. An endless rubber belt 18 is wound around the payout core 16 and the take-up core 17 so that the cores 16 and 17 rotate in unison. The rubber belt 18 may be a resin belt, or the cores 16 and 17 may be gears with concave and convex portions formed to mesh with the gears. The transfer head 14 comprises a head main body 21 having a pressure transfer unit 15 at its tip and a cylindrical support unit 20. The case 13 is provided with a bearing unit 19 that axially supports the support unit 20 of the transfer head 14. FIG. 3B is a schematic perspective view of the transfer head 14 and the bearing unit 19, and FIG. 3C is a cross-sectional view taken along line I-I in FIG. 3A. As shown in FIG. 3B, the support unit 20 of the transfer head 14 is cylindrical and rotatably supported by the bearing unit 19. With the above-described configuration, even if the case 13 of this coating film transfer tool 10 is tilted during use, the transfer head 14 rotates in the direction of arrow 22 in Figure 3C so that the entire pressure transfer portion 15 of the head main body 21 is pressed against the surface to be transferred, thereby ensuring good transfer.

[0027] In Figure 3B, the pressure transfer unit 15 is fixed integrally with the transfer head 14, but as shown in Figure 3D, the pressure transfer unit 15 may be a cylindrical or columnar roller, and the transfer pressure unit 15 may rotate when transferring from the thermally conductive transfer tape 4 to a transfer surface such as the thermally conductive sheet layer 2. When the transfer pressure unit 15 is a roller, it is preferable that the length of the roller is greater than the width of the thermally conductive transfer tape 4 so that it can uniformly press the thermally conductive transfer tape 4. In order to transfer the thermally conductive transfer tape 4 to the transfer surface such as the thermally conductive sheet layer 2, any method of attaching the roller to the transfer head 14 may be used, as long as the roller can rotate while pressing the thermally conductive transfer tape 4 against the transfer surface.

[0028] Fig. 4A is a schematic front view of a film transfer tool 23 according to a second embodiment of the present invention with the cover removed, and Fig. 4B is a partially enlarged view of the tip portion of Fig. 4A. This film transfer tool 23 includes a case 24, a payout core 25 around which the thermally conductive transfer tape 1 is wound so that it can be unwound, a spatula-shaped application part 26 for applying the tape to the surface to be transferred, a button 27 that is provided at a position protruding from the case and moves toward the inside of the case when pressed from the outside, a blade 28 that is connected to the button 27 and moves together with the button 27 to cut the thermally conductive transfer tape 1, an elastic member 29 that presses the button 27 in the direction opposite to the external pressure, and a payout part 30 that pays out the thermally conductive transfer tape 1 toward the application part 26 in conjunction with the movement of the button 27 in the direction opposite to the external pressure.

[0029] When the tip of the spatula-shaped application portion 26 of the film transfer tool 23 is pressed against the surface to be transferred, the application portion 26 presses the adhesive surface of the thermally conductive transfer tape 1 against the surface to be transferred, and when the entire film transfer tool 23 is moved in this state, the thermally conductive transfer tape 1 is unwound from the payout core 25 and applied to the surface to be transferred. The payout core 25 is provided with a brake mechanism that applies tension to the thermally conductive transfer tape 1 to prevent the unwound thermally conductive transfer tape 1 from meandering or sagging. In the film transfer tool 23, a pressing piece 32 is provided on a shaft 31 formed integrally with the case 24, and when the payout core 25 with the thermally conductive transfer tape 1 wound around it is attached to the shaft 31, the pressing piece 32 presses against the inner circumference of the payout core 25, generating a braking force. In the coating film transfer tool 23, a pressing piece 32 applies an appropriate braking force to the payout core 25, so that an appropriate tension is applied to the thermally conductive transfer tape 1 being paid out from the payout core 25, and the thermally conductive transfer tape 1 is paid out from the payout core 25 without meandering or slackening.

[0030] In the film transfer tool 23, a protrusion on the blade 28 is movable within a slot in the button 27, and the blade 28 moves in conjunction with the movement of the button 27. Therefore, in the film transfer tool 23, when the application portion 26 is pressed against the surface to be transferred and the button 27 is pressed into the case, the blade 28 connected to the button 27 moves toward the application portion 26 and cuts the thermally conductive transfer tape 1 near the tip of the application portion 26. As shown in FIG. 4B , the application portion 26 is provided with a recess 36, and when the blade 28 cuts the thermally conductive transfer tape 1, the tip of the blade 28 is inserted into this recess 36. The recess 36 makes it easier to cut the thermally conductive transfer tape 1, and the tip of the blade does not come into contact with anything other than the thermally conductive transfer tape 1, preventing damage to the blade.

[0031] An elastic member 29 is connected to the button 27. The elastic force of the elastic member 29 acts on the button 27 in the direction opposite to the pressure on the button 27 from the outside, i.e., in the direction in which the button 27 protrudes outward from the case. After the thermally conductive transfer tape 1 is cut, when the coating film transfer tool 23 is lifted from the surface to which the tape is to be applied and the external pressure on the button 27 is released, the elastic force of the elastic member 29 pushes the button 27 back in the direction in which it protrudes outward from the case, as shown in Figure 4B.

[0032] Button 27 is provided with a large number of linearly arranged triangular teeth 37, which, when button 27 moves in a direction protruding from the case to the outside, mesh with triangular teeth 30b provided on the outer periphery of the end of payout roll 30a of payout unit 30, causing payout roll 8C to rotate. Payout roll 8C sandwiches thermally conductive transfer tape 1 between itself and driven roll 33, and when payout roll 30a rotates counterclockwise in Figure 4A, the leading end of the cut thermally conductive transfer tape 1 is paid out to a position where it can be applied to the surface to be applied in application unit 26. Triangular teeth 37 and 30b tightly engage with each other when button 27 moves in a direction protruding from the case, but conversely, the tooth surfaces are inclined so that they do not easily engage with each other and slide easily when button 27 moves toward the inside of the case. Furthermore, the payout roll 30a and the cover are provided with a rotation prevention mechanism 34 that prevents the payout roll 30a from rotating in the direction opposite to the direction in which the thermally conductive transfer tape 1 is paid out toward the application section 26. Therefore, when the button 27 moves in the direction protruding from the case, the payout roll 30a also rotates in conjunction with the movement of the button 27, but when the button 27 is pressed into the case, the payout roll 30a does not rotate.

[0033] The recess 36 where the blade 28 cuts the thermally conductive transfer tape 1 is located near the tip of the application portion 26. This shortens the distance from the cutting position of the thermally conductive transfer tape 1 to the position where the thermally conductive transfer tape 1 can be applied to the surface to be applied in the application portion 26. This allows the length of the thermally conductive transfer tape 1 that the payout roll 30a pays out in one operation to be shortened. In this way, the payout length of the thermally conductive transfer tape 1 can be freely controlled. When cutting the thermally conductive transfer tape 1, the blade at the tip of the blade 28 is inserted into the recess 36 of the application portion 26 and is not exposed to the outside. In addition, the exit of the coating film transfer tool 23 that dispenses the thermally conductive transfer tape 1 toward the tip of the application portion 26 is narrow, preventing the user's fingers from entering the coating film transfer tool 23. This prevents the blade 28 cutting the correction tape from damaging the user's fingertips or the surface to be applied.

[0034] The film transfer tool 23 has a cover that is openably and closably engaged with the case. A roll cover 35 that rotatably holds a driven roll 33 is also openably and closably engaged with the case. When the cover is engaged with the case and the cover is closed, the roll cover 35 cannot be disengaged from the case and opened from the case 1. In this way, because the film transfer tool 23 has a cover and roll cover 35 that can be opened and closed with respect to the case, it is possible to open them, remove the payout core 25 that has used up the thermal conductive transfer tape 1, and install a new payout core 25 on which the thermal conductive transfer tape 1 has been wound.

[0035] 5 is a schematic cross-sectional view of a heat dissipation structure 40 incorporating a thermally conductive sheet layer according to one embodiment of the present invention. This example shows a thermally conductive transfer tape (thermally conductive sheet layers 41a and 41b) interposed between a heat-generating element and a heat sink of an electronic component, serving as a thermal interface material (TIM). The thermally conductive sheet layer 41b dissipates heat generated by an electronic component 43, such as a semiconductor device. The thermally conductive sheet layer 41b is fixed to a main surface 42a of the heat spreader 42 facing the electronic component 43, and is sandwiched between the electronic component 43 and the heat spreader 42. The thermally conductive sheet layer 41a is sandwiched between the heat spreader 42 and a heat sink 45. The thermally conductive sheet layers 41a and 41b, together with the heat spreader 42, constitute a heat dissipation member that dissipates heat from the electronic component 43. The heat spreader 42 is formed, for example, in the shape of a rectangular plate and has a main surface 42a facing the electronic component 43 and a side wall 42b extending along the outer periphery of the main surface 42a. The heat spreader 42 has a thermally conductive sheet layer 41b provided on the main surface 42a surrounded by the side wall 42b, and a heat sink 45 provided on the other surface 42c opposite the main surface 42a via the thermally conductive sheet layer 41a. The electronic component 43 is, for example, a semiconductor element such as a BGA, and is mounted on a wiring board 44.

[0036] The following description will be given using examples. The present invention is not limited to these examples. Various parameters were measured using the following methods. <Thermal Conductivity> Thermal conductivity was measured using a thermal property measuring instrument, T3Ster DynTIM Tester (manufactured by Mentor Graphics), in accordance with ASTM D5470. Specifically, thermal conductive grease G-746 (manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to both sides of the sheet, and the thermal resistance value was measured. The thermal resistance value was plotted on the vertical axis, and the measured thickness was plotted on the horizontal axis. The slope of the line between the vertical axis and the origin was calculated to calculate the thermal conductivity.

[0037] (Example 1) 1. Preparation of thermally conductive transfer tape (1) Preparation of release sheet A fluorine-based release agent was applied to one side of a 12 μm thick polyethylene terephthalate film in a dry weight of 0.2 g / m 2The film was coated with a gravure coater so that the dry weight of the fluorine-based release agent was 0.4 g / m2, and then dried with hot air to form a heavy release surface. 2 The resulting mixture was coated with a gravure coater so that the thickness was 1 / 4 of the original thickness, and then dried with hot air to form a light-release surface, yielding a release sheet. (2) Silicone Component: A commercially available addition reaction type silicone rubber was used, which consisted of a diorganopolysiloxane having a weight average molecular weight of 77,844 and containing two or more alkenyl groups per molecule as the main component, and an organohydrogenpolysiloxane having a weight average molecular weight of 1,240 as the "crosslinking agent." CAT. PL-56 (manufactured by Shin-Etsu Silicones Co., Ltd.) was used as the platinum catalyst. The amount of platinum catalyst added was 2.22 parts by weight per 100 parts by weight of silicone rubber. (3) Thermally conductive particles: Alumina A: AKP30 (Sumitomo Chemical Co., Ltd., amorphous, D50 = 0.3 μm) dry-treated with octyltriethoxysilane. Alumina B: AZ2L-75 (Nippon Steel Chemical & Material Co., Ltd., spherical, D50 = 2 μm). Aluminum nitride: TFZ-S20P (Toyo Aluminum K.K., amorphous, D50 = 20 μm). (4) Preparation of compound: A compound was prepared by kneading materials containing silicone polymer and thermally conductive filler. The resulting compound was reduced in pressure to -0.1 Pa and left for 10 minutes to degas. (5) Coating process: The compound was dissolved in a solvent and coated on the heavy release surface of a release sheet to form a thermally conductive sheet layer. Toluene was used as the solvent. The viscosity after dissolution in the solvent was 300 mPa·s when measured at 23°C using a Brookfield viscometer. (6) Drying process The coated film was dried at 150°C for 3 minutes. The total thickness of the obtained thermally conductive transfer tape was 80 μm. (7) Sheet characteristics The thermally conductive transfer tape obtained as described above was evaluated. The composition and evaluation results are summarized in Table 1 below.

[0038]

[0039] 2. Lamination of Thermally Conductive Thin Film Adhesive Layer to Thermally Conductive Transfer Tape (1) Silicone Component of Thermally Conductive Thin Film Adhesive Layer In addition to the commercially available addition reaction type silicone rubber and platinum catalyst used in the thermally conductive sheet layer, an MQ resin with a weight average molecular weight of 175,000 was used. Toluene was used as a solvent to prepare the coating liquid. The amounts of platinum catalyst, MQ resin, and toluene added were 98 parts by weight, 3.43 parts by weight, and 230 parts by weight, respectively, per 100 parts by weight of silicone rubber. MQ resin is a compound having an M unit (general formula: RSiO １／２ where R is a monovalent organic group such as a methyl group or a phenyl group) and a Q unit (general formula: SiO ４／２ It is a silicone resin with a three-dimensional structure that is soluble in solvents such as toluene. By mixing it with an addition reaction type silicone rubber and curing it, it becomes possible to adjust the release force. The MQ resin for adjusting the release force is the MQ resin R3SiO １／２ Units / SiO ４／２ Those with a molar ratio of units of 0.6 to 1.8 and a number-average molecular weight (Mn) of 5,000 to 300,000 are commercially available and are preferably used. (2) Coating Liquid for Thermally Conductive Thin Film Adhesive Layer: Alumina A, which was used for the thermally conductive sheet layer, was added to the silicone component and thoroughly stirred to prepare a coating liquid for the thermally conductive thin film adhesive layer. The amount of alumina A added was 70 parts by weight per 100 parts by weight of the silicone component excluding toluene. (3) Coating of Thermally Conductive Thin Film Adhesive Layer: The coating liquid for the thermally conductive thin film adhesive layer was applied to the thermally conductive sheet layer of the thermally conductive transfer tape using a die coater in an environment of 23°C and 50% RH, and then crosslinked in an oven at 150°C for 100 seconds to form a thermally conductive thin film adhesive layer with a thickness of 16 μm after drying, thereby obtaining a thermally conductive transfer tape with a thermally conductive thin film adhesive layer.

[0040] 3. Mounting in a Coating Film Transfer Tool The obtained thermally conductive transfer tape with a thermally conductive thin film adhesive layer was cut to a length of 10 m and a width of 6 mm to produce the thermally conductive transfer tape with a thermally conductive thin film adhesive layer shown in Figure 2. The total thickness of the obtained thermally conductive transfer tape with a thermally conductive thin film adhesive layer was 96 μm. This thermally conductive transfer tape with a thermally conductive thin film adhesive layer was wound around a payout core with the release sheet facing inward, and incorporated into a release sheet winding-type coating film transfer tool shown in Figure 3.

[0041] 4. Mounting on electronic components Using the coating film transfer tool, the thermally conductive thin film adhesive layer and the thermally conductive sheet layer were pressed and transferred onto the substrates 41b and 41a as shown in Figure 5. A heat sink was then mounted on the surface of the thermally conductive sheet layer 41a. As a result, it was confirmed that the thermally conductive sheet layer was made of cured silicone and therefore did not drip, allowing for continuous transfer.

[0042] The thermally conductive transfer tape of the present invention is suitable as a transfer tape for thermal interface materials (TIMs) that are placed between the heat generating element and the heat dissipating element of electronic components such as semiconductors. It is also suitable as a correction tape for TIM materials.

[0043] DESCRIPTION OF SYMBOLS 1, 4 Thermally conductive transfer tape 2 Thermally conductive sheet layer 3 Release sheet layer 5 Thermally conductive thin film adhesive layer 10, 23 Coating film transfer tool 11, 12 Support shaft 13, 24 Case 14 Transfer head 15 Pressure transfer section 16, 25 Payout core 17 Take-up core 18 Endless rubber belt 19 Bearing section 20 Support section 21 Head body 26 Adhesion section 27 Button 28 Blade 29 Elastic member 30 Payout section 31 Shaft 32 Pressing piece 33 Follower roll 34 Rotation prevention mechanism 35 Roll cover 36 Recess 37 Triangular teeth 40 Heat dissipation structure 41a, 41b Thermally conductive sheet layer 42 Heat spreader 43 Electronic component 44 Wiring board 45 Heat sink

Claims

1. A thermally conductive transfer tape comprising a release sheet layer and a thermally conductive sheet layer thereon, wherein the thermally conductive sheet layer contains a matrix resin and a thermally conductive filler, and the thermally conductive sheet layer can be peeled from the release sheet layer and transferred under pressure.

2. The thermally conductive transfer tape according to claim 1, wherein the thermally conductive sheet layer has a thickness of 20 μm or more and 5 mm or less.

3. The thermally conductive transfer tape according to claim 1 or 2, wherein the matrix resin is a curable silicone resin.

4. The thermally conductive transfer tape according to any one of claims 1 to 3, wherein the thermal conductivity of the thermally conductive sheet layer in accordance with ASTM D5470 is 0.8 to 20 W / m·K.

5. The thermally conductive transfer tape according to any one of claims 1 to 4, further comprising a thermally conductive thin film adhesive layer on the surface of the thermally conductive sheet layer.

6. A thermally conductive transfer tape according to any one of claims 1 to 5, wherein the thermally conductive sheet layer contains 100 to 3,000 parts by mass of a thermally conductive filler per 100 parts by mass of a matrix resin.

7. A thermally conductive transfer tape according to any one of claims 1 to 6, wherein the thermally conductive filler is at least one selected from the group consisting of aluminum oxide, zinc oxide, magnesium oxide, aluminum nitride, boron nitride, aluminum hydroxide, and silicon carbide.

8. The thermally conductive transfer tape according to any one of claims 1 to 7, which is a thermal interface material tape to be interposed between a heat generating element and a heat sink of an electronic component.

9. A method for producing a thermally conductive transfer tape according to any one of claims 1 to 8, comprising the steps of: kneading a material containing a matrix resin and a thermally conductive filler to form a compound; rolling the compound to produce a thermally conductive transfer tape of a predetermined thickness; and laminating a release sheet to one side of the thermally conductive transfer tape.

10. A method for producing a thermally conductive transfer tape according to any one of claims 1 to 8, comprising the steps of: kneading a material containing a matrix resin and a thermally conductive filler to form a compound; dissolving the compound in a solvent and applying the compound to the surface of a release sheet; and drying the applied coating.

11. A coating film transfer tool including the thermally conductive transfer tape described in any one of claims 1 to 8, characterized in that it comprises: means for rotatably storing a payout core and a take-up core within a case; means for a transfer head equipped with a transfer pressure section protruding from said case, which pays out said thermally conductive transfer tape from said payout core and presses and transfers said transfer tape onto a surface to be transferred with said transfer pressure section; and means for winding up a release sheet layer separated from said thermally conductive sheet layer onto said take-up core.

12. A coating film transfer tool including the thermally conductive transfer tape described in any one of claims 1 to 8, characterized in that it comprises: means for rotatably storing a payout core in a case; means for a transfer head equipped with a transfer pressure section protruding from said case, which pays out said thermally conductive transfer tape from said payout core and presses and transfers said transfer tape onto a surface to be transferred with said transfer pressure section; and means for cutting both said thermally conductive sheet layer and said release sheet layer.

13. A method for mounting electronic components using the thermally conductive transfer tape described in any one of claims 1 to 8, comprising the steps of: pressing and transferring the thermally conductive transfer tape onto a surface of an electronic component that includes a heat-generating portion; and mounting a heat sink on the surface of the thermally conductive sheet layer.

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