JP7129554B2 - Laminate manufacturing method and functional sheet manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a laminate containing anisotropic particles for exhibiting a specific function, a method for producing a functional sheet, and a laminate. The present invention relates to a method for manufacturing a laminate in which the orientation of tropic particles is aligned, a method for manufacturing a functional sheet, and a laminate.

Currently, there is a functional sheet in which particles are dispersed in a resin layer. Applications of the functional sheet are specified according to the properties of the particles. If thermally conductive particles are used for the particles, it becomes a thermally conductive sheet. When conductive particles are used as the particles, a conductive sheet is obtained. In the functional sheet, anisotropic particles such as plate-like, scale-like, rod-like, needle-like, and fiber-like particles are used as the particles.

Thermally conductive sheets are used to adjust the temperature of semiconductor devices used in electronic devices and electrical devices used in personal computers, general home appliances, automobiles, and the like. For example, by connecting a heat sink to an electronic device or a semiconductor device via a thermally conductive sheet, heat generated in the electronic device or the semiconductor device can be efficiently dissipated from the heat sink.
The conductive sheet is inserted between an electronic component such as a semiconductor element and a circuit board, and between wiring layers and between wiring layers, and simply pressurized to establish electrical connection and wiring between the electronic component and the circuit board. Since an electrical connection between layers can be obtained, it is widely used as an electrical connection member for electronic components such as semiconductor elements, and as an inspection connector for functional inspection. Various such thermally conductive sheets and conductive sheets have been proposed.

For example, Patent Document 1 describes a composite sheet having anisotropic thermal conductivity or anisotropic conductivity in the thickness direction of the sheet. In the method for producing a composite sheet of Patent Document 1, a sheet composition comprising a fibrous filler having magnetism and a binder that is cured by at least one of heat and light is rolled into a sheet while being rolled in the thickness direction of the sheet. A magnetic field is applied to orient the fibrous filler having magnetism in the thickness direction of the sheet, and the sheet is cured by at least one of heat and light. Patent Literature 1 describes a fibrous filler having magnetism, a conductive filler having a noble metal attached to its surface.

Patent Document 2 describes a thermally conductive adhesive film in which boron nitride powder is oriented in a certain direction in a solid adhesive. Further, Patent Document 2 describes that a magnetic field is applied to a film composition containing boron nitride powder to align and solidify the boron nitride powder in the composition to produce a thermally conductive adhesive film. It is

JP-A-2001-322139 Japanese Patent Application Laid-Open No. 2002-69392

In recent years, electronic components such as semiconductor elements and electronic equipment have been significantly downsized.
As electronic components and electronic equipment are downsized, heat generation density is increasing, and it is necessary to efficiently dissipate the heat generated from the electronic equipment and semiconductor devices. For this reason, the thermally conductive sheet is required to have good thermal conductivity.
In addition, due to the downsizing of electronic components and electronic equipment, the stability of the electrical connection of electronic components has become less stable in methods such as conventional wire bonding that directly connects wiring boards, flip chip bonding, and thermocompression bonding. cannot be fully guaranteed. Therefore, there is a demand for a conductive sheet that can be used as an electronic connecting member that can guarantee the stability of electrical connection even if it is downsized.

In order to exhibit the required performance in both the thermally conductive sheet and the electrically conductive sheet, anisotropic particles are used, and the long axis of the anisotropic particles is the direction in which heat is to be conducted or the direction in which the anisotropic particles are conducting. In addition, it is necessary to align the orientation of a plurality of anisotropic particles. Also, the higher the content of the anisotropic particles, the better the thermal conductivity and electrical conductivity.
However, when the content of the anisotropic particles increases, the magnetic field must be strengthened if a magnetic field is used for orienting the anisotropic particles, and the long axis of the anisotropic particles is more appropriately aligned. It becomes difficult to align the particles and to align the orientation of a plurality of anisotropic particles. As described above, there is currently a demand for a manufacturing method capable of appropriately orienting the long axes of anisotropic particles and aligning the orientation of a plurality of anisotropic particles.

An object of the present invention is to solve the above-mentioned problems based on the conventional technology, to properly orient the long axes of anisotropic particles, and to manufacture a laminate capable of aligning the orientation of a plurality of anisotropic particles. An object of the present invention is to provide a method, a method for producing a functional sheet, and a laminate.

In order to achieve the above object, the present invention provides a process of laminating a heat-shrinkable thermoplastic resin substrate and a functional layer containing a plurality of anisotropic particles and a binder;
The thermoplastic resin substrate on which the functional layer is laminated is heated to a temperature equal to or higher than the glass transition temperature of the thermoplastic resin substrate to shrink the thermoplastic resin substrate, and the long axes of the plurality of anisotropic particles are and a step of orienting the functional layer in the film thickness direction.
The step of laminating the thermoplastic resin substrate and the functional layer may include applying a coating composition containing a plurality of anisotropic particles and a binder onto the heat-shrinkable thermoplastic resin substrate. preferable.
The step of orienting the long axes of a plurality of anisotropic particles in the film thickness direction of the functional layer includes heating the thermoplastic resin substrate to a temperature equal to or higher than the glass transition temperature to shrink the thermoplastic resin substrate uniaxially. It is preferable to let

The present invention comprises a step of forming a laminated material by laminating a heat-shrinkable thermoplastic resin base material and a functional layer containing a plurality of anisotropic particles and a binder, and A step of heating the thermoplastic resin substrate to a temperature equal to or higher than the glass transition temperature of to shrink the thermoplastic resin substrate, and orienting the long axes of the plurality of anisotropic particles in the film thickness direction of the functional layer; and removing the substrate from the laminated material.
The step of forming a laminated material by laminating a thermoplastic resin substrate and a functional layer includes applying a coating composition containing a plurality of anisotropic particles and a binder onto a heat-shrinkable thermoplastic resin substrate. It is preferable to have a step of
The step of orienting the long axes of the plurality of anisotropic particles in the film thickness direction of the functional layer includes heating the laminated material to a temperature equal to or higher than the glass transition temperature of the thermoplastic resin substrate, thereby dissolving the thermoplastic resin substrate. Uniaxial shrinkage is preferred.
The step of removing the thermoplastic resin base material after shrinkage from the laminated material is preferably a step of immersing the laminated material in a solvent to dissolve the thermoplastic resin base material.
The step of removing the thermoplastic resin base material after shrinkage from the laminated material is also preferably a step of peeling the thermoplastic resin base material from the laminated material.

The present invention provides a laminate having a substrate and a functional layer containing a plurality of anisotropic particles and a binder, wherein the content of the plurality of anisotropic particles in the functional layer is 40% by volume or more. and the long axes of a plurality of anisotropic particles are oriented at an average inclination angle of 50° or more with respect to the back surface of the functional layer.
The plurality of anisotropic particles preferably have thermal conductivity. The plurality of anisotropic particles having thermal conductivity are preferably tabular particles made of boron nitride.
The content of the plurality of anisotropic particles in the functional layer is preferably 45-65% by volume.

According to the present invention, it is possible to obtain a laminate and a functional sheet in which the long axes of anisotropic particles are properly oriented and the orientation of a plurality of anisotropic particles is aligned.

BRIEF DESCRIPTION OF THE DRAWINGS It is typical sectional drawing which shows an example of the laminated body of embodiment of this invention. FIG. 3 is a schematic perspective view showing anisotropic particles in the laminate of the embodiment of the invention. FIG. 4 is a schematic diagram showing the tilt angles of the anisotropic particles in the laminate of the embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the 1st example of the electronic device using the functional sheet of embodiment of this invention. FIG. 4 is a schematic diagram showing a second example of an electronic device using the functional sheet of the embodiment of the invention. FIG. 2 is a schematic diagram showing an example of arrangement of terminals of a semiconductor element; BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows 1 process of the manufacturing method of the laminated body of embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows 1 process of the manufacturing method of the laminated body of embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows 1 process of the manufacturing method of the functional sheet of embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows 1 process of the manufacturing method of the functional sheet of embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows 1 process of the manufacturing method of the functional sheet of embodiment of this invention. 4 is a graph showing the analysis results by the X-ray diffraction method of Example 2. FIG. 10 is a graph showing the analysis results by the X-ray diffraction method of Comparative Example 1. FIG.

Hereinafter, the method for producing a laminate, the method for producing a functional sheet, and the laminate of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
It should be noted that the drawings described below are examples for explaining the present invention, and the present invention is not limited to the drawings shown below.
In the following, "~" indicating a numerical range includes the numerical values described on both sides. For example, when ε ₁ is numerical value α ₁ to numerical value β ₁ , the range of _{ε 1} is the range including numerical value α ₁ and _numerical value _{β 1} .
Angles such as “specified numerical angle,” “parallel,” “perpendicular,” and “perpendicular,” unless otherwise specified, include the generally accepted error ranges in the relevant technical fields.

(Laminate)
The laminate has a substrate, a functional layer containing a plurality of anisotropic particles and a binder, the content of the plurality of anisotropic particles in the functional layer is 40% by volume or more, and a plurality of The long axes of the anisotropic particles are oriented at an average tilt angle of 50° or more with respect to the back surface of the functional layer. The long axes of the plurality of anisotropic particles in the functional layer are oriented at an average inclination angle of 50° or more with respect to the surface of the functional layer on which the substrate is provided in the laminate. ing.
FIG. 1 is a schematic cross-sectional view showing an example of a laminate according to an embodiment of the invention.
The laminate 10 shown in FIG. 1 has a substrate 12 and a functional layer 14 containing a plurality of anisotropic particles 15 and a binder 16. The substrate 12 and the functional layer 14 are laminated in the lamination direction Dt. It is The anisotropic grains 15 are tabular grains, for example. The content of the anisotropic particles 15 in the functional layer 14 is 40% by volume or more. The content of the anisotropic particles 15 will be described later in detail.
The properties of laminate 10 are determined by the properties of anisotropic particles 15 . For example, if the anisotropic particles 15 have conductivity in the film thickness direction D, the laminate 10 exhibits anisotropic conductivity and can be used as an anisotropically conductive sheet. Also, if the anisotropic particles 15 have thermal conductivity in the thickness direction D, for example, the laminate 10 exhibits thermal conductivity and can be used as an anisotropic thermally conductive sheet.
In addition, in the laminate 10, the functional layer 14 may be in a cured state or in a semi-cured state.

As shown in FIG. 1, a release layer 18 is provided on the surface 14a of the functional layer 14, for example. The laminate 10 is used with the release layer 18 removed. For this reason, the peeling layer 18 may be omitted, but it is preferable that the peeling layer 18 is present in order to facilitate handling such as transportation of the laminate 10 . For the release layer 18, for example, a film is used in which a silicone-based adhesive or a non-silicone-based adhesive is applied to a supporting substrate to impart a release function. As the supporting substrate, for example, polyethylene terephthalate (PET), polyester, polypropylene, polyethylene, and the like can be used.
In the laminated body 10, the substrate 12 and the functional layer 14 are laminated.

FIG. 2 is a schematic perspective view showing anisotropic particles in the laminate of the embodiment of the present invention, and FIG. 3 is a schematic diagram showing the inclination angles of the anisotropic particles in the laminate of the embodiment of the present invention. .
As shown in FIG. 2, the anisotropic particles 15 have the longest axis of the anisotropic particles 15, that is, the long axis Da, and the shortest axis, that is, the short axis Dc. It is orthogonal to the short axis Dc, and the long axis Da and the short axis Dc have different lengths. The anisotropic particles 15 are anisotropic in shape. The anisotropic grain 15 shown in FIG. 2 is a rectangular parallelepiped tabular grain, and the major axis Da is the length in the direction in which the longest side extends, and the minor axis Dc is the length of the portion corresponding to the thickness. Further, for example, when the anisotropic particles are fibrous or columnar, the major axis Da is the length in the direction in which the fibers or columns extend, and the minor axis Dc is the length of the portion corresponding to the diameter.
The ratio of the average value of the long axis Da to the average value of the short axis Dc is the aspect ratio. The aspect ratio will be explained later.
The anisotropic particles 15 are also anisotropic in nature, and it is preferable that thermal conductivity, electrical conductivity, or the like in the longitudinal direction, which will be described later, is greater than in other directions. In this case, by orienting the long axis Da of the anisotropic particles 15 in the film thickness direction D of the functional layer 14, the thermal conductivity, electrical conductivity, and the like are most excellent.

In FIG. 2 , the long axis Da of the plurality of anisotropic particles 15 is oriented in the film thickness direction D of the functional layer 14 . The film thickness direction D of the functional layer 14 is parallel to the lamination direction Dt described above.
The major axis Da of the plurality of anisotropic particles 15 has an average inclination angle of 50° or more with respect to the back surface 14b of the functional layer 14 . If the average inclination angle is 50° or more, performance required for the laminate 10, such as electrical conductivity or thermal conductivity, can be exhibited.
The orientation state of the anisotropic particles 15 is represented by an inclination angle θ of the major axis Da with respect to the back surface 14b of the functional layer 14, as shown in FIG. The inclination angle θ is the angle between the rear surface 14b of the functional layer 14 and the major axis Da. The tilt angle θ can take multiple angles with respect to the back surface 14b of the functional layer 14, as shown in FIG. Let the smallest angle among a plurality of possible angles be the inclination angle θ.
The average tilt angle described above is the average value of the tilt angles θ of the plurality of anisotropic particles 15 with respect to the back surface 14 b of the functional layer 14 .
As for the orientation of the anisotropic particles 15, it is ideal that the long axis Da is perpendicular to the back surface 14b, that is, at 90°. Therefore, the upper limit of the average tilt angle is 90°. The average tilt angle of 90° is the arrangement state of the anisotropic particles 15 shown in FIG. A method for measuring the average tilt angle will be described later in detail.

For example, the plurality of anisotropic particles 15 are oriented such that the surface 15a is parallel to the plane _PL perpendicular to the surface 14a of the functional layer 14 . Note that the plane PL shown in FIG. 2 is one of the planes _{perpendicular} to the surface _14a , and is not limited to the plane PL. A myriad of planes perpendicular to the surface _14a exist in different orientations from the plane PL. Therefore, the direction of the flat anisotropic grains 15 is not particularly limited.
The direction of the surfaces 15a of the plate-like anisotropic particles 15 may be aligned in all the anisotropic particles 15, or may be in a random state. In addition, since the contact area between the functional layer 14 and the object to be connected can be secured, the heat conduction can be stabilized, and the conduction can be stabilized, the flat anisotropic particles 15 have the surfaces 15a aligned and oriented. preferably. Therefore, it is preferable that 80% or more of the total number of anisotropic particles 15 are parallel to each other. In addition, as shown in FIG. 2, the surface 15a of the anisotropic particle 15 is ideally oriented parallel to the plane _PL perpendicular to the surface 14a of the functional layer . In this case, the tilt angle θ of the anisotropic particles 15 is 90°.

Further, by making the shape of the anisotropic particles 15 tabular, the area of the surface 14a of the functional layer 14 can be made smaller compared to spherical anisotropic particles. Thereby, the filling rate of the anisotropic particles 15 can be increased. If the anisotropic particles 15 have thermal conductivity, the contact area with the object to be connected can be increased while the thermal conductivity of the functional layer 14 of the laminate 10 is maintained. can be maintained. If the anisotropic particles 15 have conductivity, the contact area with the object to be connected can be increased while maintaining the conductivity of the functional layer 14 of the laminate 10, and the adhesion can be maintained. can do.

Applications of the laminate 10 and the functional sheet 20 include, for example, heat radiation from electronic components such as semiconductor elements and electronic equipment. In addition to this, it can be used for electrical connection of electronic parts such as semiconductor elements and electronic equipment, or electrical connection between wiring layers or between wiring boards. Applications of the functional sheet will be described below.

(electronic device)
Next, an electronic device using a functional sheet will be described.
FIG. 4 is a schematic diagram showing a first example of an electronic device using the functional sheet of the embodiment of the present invention, and FIG. 5 is a second example of an electronic device using the functional sheet of the embodiment of the present invention. It is a schematic diagram which shows an example. In FIGS. 4 and 5, the functional sheet 20 is the laminated body 10 with the substrate 12 removed and the functional layer 14 alone as described above.
The electronic device 30 shown in FIG. 4 has a configuration in which a thermally conductive sheet is used as the functional sheet 20, and a semiconductor element 32 and a heat sink 34 are laminated in the lamination direction Dt with the functional sheet 20 interposed therebetween. In this case, the heat generated in the semiconductor element 32 is thermally conducted to the heat sink 34 through the functional sheet 20 and radiated by the heat sink 34, so that the temperature rise of the semiconductor element 32 is suppressed. Note that the electronic device 30 shown in FIG. 4 is not limited to the semiconductor element 32, and a thermoelectric element can be used instead of the semiconductor element 32. FIG. Also, the functional sheet 20, which is a thermally conductive sheet, can be used as a radiator without providing the heat sink 34. FIG.

In addition to the above-described configuration, an anisotropically conductive sheet is used as the functional sheet 20, and the semiconductor element 32 and the semiconductor are connected to the semiconductor element 32 via the functional sheet 20 exhibiting anisotropic conductivity, as in the electronic device 31 shown in FIG. The semiconductor element 32 and the semiconductor element 36 can also be electrically connected by joining the element 36 in the stacking direction Dt. In the electronic device 31 shown in FIG. 5, electrical conductivity is ensured between the semiconductor element 32 and the semiconductor element 36, and adhesion is excellent.
The semiconductor elements 32 and 36 have, for example, a plurality of terminals 35 as shown in FIG. Even if the size of the terminal 35 is a rectangle of 10 μm on each side and the interval between the terminals 35 is 10 μm, the semiconductor element 32 and the semiconductor element 36 can be electrically connected by using the functional sheet 20 described above. be able to.

Other than the configuration described above, it may function as an optical sensor. In this case, a semiconductor element (not shown) and a sensor chip (not shown) are stacked in the stacking direction Dt via a functional sheet 20, which is an anisotropically conductive sheet. Also, the sensor chip is provided with a lens (not shown). The semiconductor element is formed with a logic circuit, and its configuration is not particularly limited as long as the signal obtained by the sensor chip can be processed. The sensor chip has an optical sensor that detects light. The optical sensor is not particularly limited as long as it can detect light, and for example, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor is used.
The configuration of the lens is not particularly limited as long as it can focus light on the sensor chip, and for example, a so-called microlens is used.

The semiconductor element 32 and the semiconductor element 36 described above have, for example, a semiconductor layer (not shown) and an element region (not shown).
The element region is a region in which various element-constituting circuits such as capacitors, resistors, and coils are formed for functioning as electronic elements. In the element region, for example, memory circuits such as flash memories, regions in which logic circuits such as microprocessors and FPGAs (field-programmable gate arrays) are formed, communication modules such as wireless tags, and wiring are formed. There is an area In addition to this, an oscillating circuit or MEMS (Micro Electro Mechanical Systems) may be formed in the element region. MEMS are, for example, sensors, actuators and antennas. Sensors include, for example, various sensors such as acceleration, sound, and light.

As described above, an element configuration circuit and the like are formed in the element region, and a rewiring layer is provided in the semiconductor element.
An electronic device may be, for example, a combination of a semiconductor element having a logic circuit and a semiconductor element having a memory circuit. Further, all of the semiconductor elements may have memory circuits, or all of them may have logic circuits. A combination of semiconductor elements in the electronic device 30 may be a combination of a sensor, an actuator, an antenna, etc., and a memory circuit and a logic circuit.

Moreover, the semiconductor element is not particularly limited, and specific examples include the following. Examples of semiconductor devices include logic integrated circuits such as ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), and ASSPs (Application Specific Standard Products), in addition to those described above. Further, for example, microprocessors such as CPUs (Central Processing Units) and GPUs (Graphics Processing Units) are included. Also, for example, DRAM (Dynamic Random Access Memory), HMC (Hybrid Memory Cube), MRAM (Magnetoresistive Random Access Memory), PCM (Phase-Change Memory), ReRAM (Resistance Random Access Memory), FeRAM (Ferroelectric Random Access Memory) , flash memory, and the like. Further examples include analog integrated circuits such as LEDs (Light Emitting Diodes), power devices, DC (Direct Current)-DC (Direct Current) converters, and insulated gate bipolar transistors (IGBTs).
Furthermore, semiconductor devices include GPS (Global Positioning System), FM (Frequency Modulation), NFC (Near Field Communication), RFEM (RF Expansion Module), MMIC (Monolithic Microwave Integrated Circuit), WLAN (Wireless Local Area Network), ), discrete elements, passive devices, SAW (Surface Acoustic Wave) filters, RF (Radio Frequency) filters, and IPDs (Integrated Passive Devices). A TEG (Test Element Group) chip may be used as the semiconductor element.

In addition to semiconductor elements, interposers and TAB (Tape Automated Bonding) tapes can also be objects to be connected. Furthermore, it can be used for connection between an electrode pad of a transparent conductive film and an electrode pad of FPC (Flexible Printed Circuits) as an object to be connected. It can also be used to directly connect and mount an IC (Integrated Circuit) chip on the electrode pad of the transparent conductive film. The transparent conductive film is not particularly limited as long as it has low visibility and is difficult to see. A conductive film composed of thin metal wires on the order of several μm may also be used. Moreover, as the transparent conductive film, for example, various conductive films used for touch sensors and the like can be appropriately used.
Also, the IC chip has, for example, a plurality of terminals 35 as shown in FIG. 6, like the semiconductor elements 32 and 36.

Next, a method for manufacturing the laminate and the functional sheet will be described.
(Laminate manufacturing method)
7 and 8 are schematic diagrams showing one step of the method for manufacturing the laminate according to the embodiment of the present invention. 7 and 8, the same components as those of the laminate 10 shown in FIG. 1 and the functional layer 14 shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

A method for producing a laminate includes a step of laminating a heat-shrinkable thermoplastic resin substrate and a functional layer containing a plurality of anisotropic particles and a binder, and a thermoplastic resin substrate on which the functional layer is laminated. is heated to a temperature equal to or higher than the glass transition temperature of the thermoplastic resin substrate to shrink the thermoplastic resin substrate and orient the long axes of the plurality of anisotropic particles in the film thickness direction of the functional layer; have By heating and shrinking the thermoplastic resin substrate on which the functional layer is laminated, the long axes of the plurality of anisotropic particles are oriented in the film thickness direction of the functional layer.
In the method of manufacturing the laminate 10 shown in FIG. 1, as shown in FIG. 7, a heat-shrinkable thermoplastic resin substrate 40 and a functional layer 14 containing anisotropic particles 15 and a binder 16 are laminated.
Next, the thermoplastic resin substrate 40 laminated with the functional layer 14 is heated to a temperature equal to or higher than the glass transition temperature of the thermoplastic resin substrate 40 using, for example, a heating furnace. The plastic resin base material 40 is shrunk. At this time, the anisotropic particles 15 of the functional layer 14 are brought together in the contraction direction, and as shown in FIG. D oriented. As a result, it is possible to obtain the layered product 10 (see FIG. 1) in which the anisotropic particles are appropriately arranged at an orientation angle and the like, and the plurality of anisotropic particles are uniformly oriented.
The glass transition temperature (Tg) is measured using a differential scanning calorimeter DSC7000X manufactured by Hitachi High-Tech Science Co., Ltd. under the conditions of a nitrogen atmosphere and a heating rate of 20 ° C./min, and the time derivative DSC curve of the obtained results. The temperature at the intersection of the peak top temperature of (DDSC curve) and the tangent line of each DSC curve at a temperature of −20° C. from this peak top temperature.
In the method for manufacturing the laminate 10, the thermoplastic resin base material 40 is shrunk, and no magnetic force or the like is required. Therefore, manufacturing equipment can be simplified, and manufacturing costs can be reduced. Furthermore, even if the content of the anisotropic particles 15 in the functional layer 14 is as large as 40% by volume or more, the anisotropic particles can be regenerated with small energy due to shrinkage of the thermoplastic resin base material 40 without using a magnetic force or the like. 15 can be oriented. The higher the content of the anisotropic particles, the more the functions peculiar to the anisotropic particles, such as thermal conductivity and electrical conductivity, can be obtained.
Also, since the anisotropic particles 15 do not need to be magnetic, many types of anisotropic particles 15 can be used.

<Laminate manufacturing process>
In the step of laminating the thermoplastic resin substrate 40 and the functional layer 14 shown in FIG. It is applied on the substrate 40, that is, on the surface 40a. After applying the coating composition 42, it may be heated at a temperature below the glass transition temperature and dried to form a coating film.
In addition to the coating described above, for example, the functional layer 14 may be attached to the thermoplastic resin substrate 40 to laminate the thermoplastic resin substrate 40 and the functional layer 14 .
The step of orienting the long axis Da (see FIG. 2) of the anisotropic particles 15 shown in FIG. Preferably, the thermoplastic resin substrate 40 is uniaxially shrunk by heating. To uniaxially shrink the thermoplastic resin substrate 40 means to shrink the thermoplastic resin substrate 40 in any one direction within the surface 40 a of the thermoplastic resin substrate 40 . It should be noted that shrinking in two axial directions means shrinking the thermoplastic resin substrate 40 in any two directions that intersect within the surface 40a of the thermoplastic resin substrate 40 . When biaxially shrunk, the contraction rate of the thermoplastic resin substrate 40 can be increased, so the angle formed by the two axes is preferably 90°.

When uniaxially shrunk as described above, for example, the rectangular thermoplastic resin substrate 40 is shrunk by heating to a temperature equal to or higher than the glass transition temperature while fixing two opposite sides in the non-shrinking direction. When biaxially shrunk as described above, for example, a biaxially oriented material is used for the thermoplastic resin substrate 40 .
The means for raising the temperature of the thermoplastic resin substrate 40 to the glass transition temperature or higher is not limited to the heating furnace described above, and hot air, superheated steam, hot water, electric heaters, infrared rays, microwaves, etc. are used. can also
Moreover, the method for manufacturing the laminate may include a curing step of heating and curing the functional layer after shrinking the thermoplastic resin base material 40 . When curing the functional layer, the heating temperature may be equal to or higher than the glass transition temperature of the thermoplastic resin substrate 40 .

<Thermoplastic resin substrate>
The heat-shrinkable thermoplastic resin substrate 40 is a substrate whose area shrinks by 20% or more after being held at the glass transition temperature for 24 hours.
The base material 12 of the laminate 10 shown in FIG. 1 is composed of, for example, a base material after heat shrinkage, and does not heat shrink. In this case, substrate 12 shrinks in area by less than 20% after being held at the glass transition temperature for 24 hours. That is, the substrate 12 has a shrinkage ratio St of less than 20% after being held at the glass transition temperature for 24 hours. The above-mentioned "no thermal shrinkage" means that the shrinkage ratio St is less than 20% after holding at the glass transition temperature for 24 hours.
For the heat-shrinkable thermoplastic resin base material 40, for example, a material suitable for the direction of shrinkage is used.
When uniaxially shrunk as described above, for example, a uniaxially stretched resin material is used for the thermoplastic resin substrate 40 . When biaxially shrunk as described above, for example, a biaxially stretched resin material is used for the thermoplastic resin substrate 40 .
Polystyrene, polyvinyl chloride, and polymethyl methacrylate, for example, can be used for the thermoplastic resin base material 40 .

The anisotropic particles 15 are oriented by shrinking the heat-shrinkable thermoplastic resin substrate 40. At this time, the thermoplastic resin substrate 40 after shrinking is thicker than before shrinking. , the thickness of the functional layer 14 also becomes thicker than before shrinkage. The thermoplastic resin base material 40 preferably has a shrinkage rate of 35% or more and 80% or less, more preferably 50% or more and 75% or less.
Regarding the shrinkage rate of the thermoplastic resin substrate 40, the shrinkage rate is St (%), the area of the thermoplastic resin substrate 40 before shrinkage is _A1 , and the area of the thermoplastic resin substrate 40 after shrinkage is _A2 . , St(%)=(1−(A ₂ /A ₁ ))×100.

(Manufacturing method of functional sheet)
9 to 11 are schematic diagrams showing one step of the method for producing a functional sheet according to an embodiment of the present invention. 9 to 11, the same components as those of the laminate 10 shown in FIG. 1 and the functional layer 14 shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. Further, the thermoplastic resin base material 40 is as described in the above-described method for manufacturing a laminate.
In the method for producing a functional sheet, as shown in FIG. 9, a heat-shrinkable thermoplastic resin substrate 40 and a functional layer 14 containing a plurality of anisotropic particles 15 and a binder 16 are laminated to form a laminated material. form 44;
Next, the laminated material 44 is heated to a temperature equal to or higher than the glass transition temperature of the thermoplastic resin base material 40 to cause the thermoplastic resin base material 40 to shrink and the length of the anisotropic particles 15 to increase, as shown in FIG. The axis Da (see FIG. 2) is oriented in the thickness direction D of the functional layer 14 .
Next, the thermoplastic resin base material 40 is removed from the laminated material 44 shown in FIG. This makes it possible to obtain the functional sheet 20 (see FIG. 11) in which the anisotropic particles 15 are arranged at an appropriate orientation angle and the orientation of the plurality of anisotropic particles 15 is uniform.
After removing the thermoplastic resin base material 40 from the laminated material 44, it is preferable to have a curing step of heating and curing the functional layer. When curing the functional layer, the heating temperature may be equal to or higher than the glass transition temperature of the thermoplastic resin substrate 40 .

In the method for manufacturing the functional sheet 20, the thermoplastic resin base material 40 is shrunk in the same manner as in the method for manufacturing the laminate 10, and no magnetic force or the like is required. Therefore, manufacturing equipment can be simplified, and manufacturing costs can be reduced. Furthermore, even if the content of the anisotropic particles 15 in the functional layer 14 is as large as 40% by volume or more, the anisotropic particles can be regenerated with small energy due to shrinkage of the thermoplastic resin base material 40 without using a magnetic force or the like. 15 can be oriented. As the content of the anisotropic particles increases, a functional sheet capable of exhibiting functions specific to the anisotropic particles, such as thermal conductivity and electrical conductivity, can be obtained.
Also, since the anisotropic particles 15 do not need to be magnetic, many types of anisotropic particles 15 can be used.

<Process of manufacturing functional sheet>
In the step of forming the laminated material 44 of the thermoplastic resin substrate 40 and the functional layer 14 shown in FIG. is applied to the thermoplastic resin substrate 40, that is, to the surface 40a. After applying the coating composition 42, it may be dried at a temperature below the glass transition temperature to form a coating film.
In addition to coating, for example, the functional layer 14 may be attached to the thermoplastic resin substrate 40 to laminate the thermoplastic resin substrate 40 and the functional layer 14 .

The step of orienting the long axis Da (see FIG. 2) of the anisotropic particles 15 shown in FIG. It is preferable to uniaxially shrink the thermoplastic resin substrate 40 by heating to the above temperature. The process of uniaxially shrinking the thermoplastic resin base material 40 is the same as in the above-described method of manufacturing the laminate 10, so detailed description thereof will be omitted.
Although the thermoplastic resin substrate 40 is removed from the laminated material 44 shown in FIG. The thermoplastic resin substrate 40 can be removed from the laminate 44 by dissolving the material 40 . A solvent that can dissolve the thermoplastic resin base material 40 is used. When the thermoplastic resin base material 40 is polystyrene, limonene is used as the solvent.
Furthermore, the step of removing the thermoplastic resin base material 40 from the laminated material 44 is, for example, a step of peeling the thermoplastic resin base material 40 from the laminated material 44 to remove the thermoplastic resin base material 40 from the laminated material 44. can also

<Production of coating composition>
When the coating composition is obtained, the laminate and the functional sheet are preferably dispersed by mixing the anisotropic particles with the binder while cooling the binder. The dispersing treatment is carried out using a high-speed stirrer or homogenizer capable of sufficiently stirring the particles so that the anisotropic particles do not agglomerate and having a shearing force. The device that performs distributed processing is not particularly limited to the above-described device, and can be selected as appropriate. The reason why the dispersing treatment is performed while cooling is that there is a possibility that high agitation heat is generated when dispersing by strong agitation in order to obtain a good dispersed state. To what extent the heat of stirring is appropriate depends on the type of the curable compound, so it is appropriately determined according to the binder. The dispersed and mixed liquid is applied onto a thermoplastic resin substrate so that the functional layer has a specified thickness.
The method for changing the thickness of the functional layer is not particularly limited, but it is desirable that the thickness difference already exists after coating. When changing the coating thickness with an applicator, it can be changed by changing the gap between the thermoplastic resin substrate and the applicator. Also, the coating thickness can be changed by a method of scraping off the liquid after once coating. In addition, when a fixed amount of coating is applied from the coating head, the thickness can also be changed by changing the relative speed between the thermoplastic resin substrate and the coating head and the supply speed. Furthermore, it is possible to change the thickness by coating with an inkjet method. The coating method for forming the functional layer can be appropriately determined depending on the purpose, the binder, and the like.

The laminate 10 and the functional sheet 20 will be described in more detail below.
〔Base material〕
The substrate supports the functional layer in the laminate, and is composed of, for example, a thermoplastic resin substrate that has shrunk during the manufacturing process of the laminate. The base material is composed of a material that does not heat shrink. The substrate is not limited to a thermoplastic resin substrate after shrinkage, as long as it does not thermally shrink and can support the functional layer. Not thermally shrinking is as described above.
In the laminate, the functional layer is separated from the substrate, and the functional layer alone is used as a functional sheet. In this case, the substrate also functions as a protective layer for conveying the functional sheet. As the base material, the same material as the release layer described above can be used.
Moreover, the base material can also have performance according to the application of the functional sheet. For example, in the case of a thermally conductive sheet, a substrate with high thermal conductivity can be used.

[Anisotropic particles]
Anisotropic particles have anisotropic shape or property as described above. Specific examples of the anisotropic particles will be described below.

<Thermal conductive particles>
Thermally conductive particles having thermal conductivity can be used as the anisotropic particles. In this case, the thermally conductive particles preferably have greater thermal conductivity in the longitudinal direction than in other directions.
As the anisotropic particles as the thermally conductive particles, inorganic substances conventionally used as inorganic fillers for thermally conductive materials are used, but tabular particles made of boron nitride (BN) are preferable. The inorganic substance preferably contains an inorganic nitride or an inorganic oxide, and more preferably contains an inorganic nitride, from the viewpoint that the thermal conductivity and insulation properties of the thermally conductive material are more excellent.

Examples of inorganic oxides include zirconium oxide (ZrO ₂ ), titanium oxide (TiO ₂ ), silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), iron oxide (Fe ₂ O ₃ , FeO, Fe ₃ O ₄ ), copper oxides (CuO, Cu ₂ O), zinc oxide (ZnO), yttrium oxide (Y ₂ O ₃ ), niobium oxide (Nb ₂ O ₅ ), molybdenum oxide (MoO ₃ ), indium oxide (In ₂ O ₃ , In ₂ O), tin oxide (SnO ₂ ), tantalum oxide (Ta ₂ O ₅ ), tungsten oxide (WO ₃ , W ₂ O ₅ ), lead oxide (PbO, PbO ₂ ), bismuth oxide (Bi ₂ O3) _, cerium oxide ₍ CeO2 _{, Ce2O3} ) _, antimony oxide ₍ Sb2O3, _Sb2O5 ) _, germanium oxide _{( GeO2} , GeO), lanthanum oxide ₍ La2O3), and Ruthenium oxide (RuO ₂ ) and the like are included.
Only one kind of the above inorganic oxides may be used, or two or more kinds thereof may be used.
The inorganic oxide is preferably titanium oxide, aluminum oxide, or zinc oxide, more preferably aluminum oxide.
The inorganic oxide may be an oxide produced by oxidizing a metal prepared as a non-oxide in the environment or the like.

Examples of inorganic nitrides include boron nitride (BN), carbon nitride ( _C3N4 ), silicon nitride _{( Si3N4} ), gallium nitride ₍ GaN), indium nitride (InN), aluminum nitride (AlN), Chromium nitride ( _Cr2N ), copper nitride ( _Cu3N ), iron nitride ( _Fe4N ), iron nitride ( _Fe3N ), lanthanum nitride (LaN), lithium nitride ( _Li3N ), magnesium nitride (Mg _{3N 2} ), molybdenum nitride (Mo ₂ N), niobium nitride (NbN), tantalum nitride (TaN), titanium nitride (TiN), tungsten nitride (W ₂ N), tungsten nitride (WN ₂ ), yttrium nitride (YN ), and zirconium nitride (ZrN).
The inorganic nitride preferably contains aluminum atoms, boron atoms, or silicon atoms, more preferably aluminum nitride, boron nitride, or silicon nitride, more preferably aluminum nitride or boron nitride, It is particularly preferred to contain boron nitride.
Only one of the inorganic nitrides described above may be used, or two or more thereof may be used.

Although the size of the inorganic substance is not particularly limited, the average particle size of the inorganic substance is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less, in terms of better dispersibility of the inorganic matter. Although the lower limit is not particularly limited, it is preferably 10 nm or more, more preferably 100 nm or more, in terms of handleability.
As for the average particle diameter of the inorganic substance, the catalog value is adopted when using a commercially available product. If there is no catalog value, the above average particle size can be measured by measuring the particle size distribution (volume basis) of the powder with a laser diffraction particle size distribution measuring device to obtain the volume average particle size (Mv). .

Only one kind of inorganic substance may be used, or two or more kinds thereof may be used.
The inorganic substance preferably contains at least one of an inorganic nitride and an inorganic oxide, and more preferably contains at least an inorganic nitride.
The above inorganic nitride preferably contains at least one of boron nitride and aluminum nitride, and more preferably contains at least boron nitride.
The content of the inorganic nitride (preferably boron nitride) in the inorganic substance is preferably 10% by mass or more, more preferably 50% by mass or more, and even more preferably 80% by mass or more, relative to the total mass of the inorganic substance. An upper limit is 100 mass % or less.
Aluminum oxide is preferable as the above inorganic oxide.
The composition more preferably contains at least an inorganic substance having an average particle size of 20 μm or more (preferably 40 μm or more), in order to improve the thermal conductivity of the heat conductive material.

<Conductive particles>
Conductive particles having conductivity can be used as the anisotropic particles. In this case, the conductive particles preferably have greater conductivity in the longitudinal direction than in other directions.
Examples of conductive particles that can be used include, but are not limited to, aluminum flakes, silver nanodisks, and silver nanorods.
Also, as the conductive particles, for example, particles having compositions such as CoCr and CoPt can be used. Furthermore, particles having a composition such as BaFe (barium ferrite) and SrFe (strontium ferrite) formed with a conductive layer for imparting conductivity can be used.
The conductive layer is composed of, for example, a metal film or a carbon film.
The metal film is composed of, for example, a single metal film such as Au, Cu, Ag, or Ni, or an alloy film of these metals. A metal film is formed by, for example, a plating method, a vapor deposition method, and a sputtering method. Also, the carbon film is formed by, for example, CVD (Chemical Vapor Deposition).
As described above, the method for manufacturing the laminate and the functional sheet does not use magnetic force or the like, so the conductive particles do not need to be magnetic.

<Average tilt angle>
The average tilt angle of a plurality of anisotropic particles can be obtained by X-ray diffraction method and observation of the anisotropic particles.
In the X-ray diffraction method, a plurality of anisotropic particles are irradiated with X-rays, and the relationship between the X-ray diffraction intensity and the diffraction angle is obtained. From the result, the peak intensity ratio R between the X-ray diffraction intensity I _{[002] of [002]} and the X-ray diffraction intensity I _[100] of [100] is obtained. Based on the peak intensity ratio R=I _[002] /I _[100] , the following formula is used to obtain the average tilt angle θa. Note that α in the following formula is a constant, which is an intrinsic constant determined by the composition of the anisotropic particles. For example, α for hexagonal boron nitride is 6.25.
θa=cos ⁻¹ {R/(R+2×α)} ^0.5
The above-described method of calculating the average tilt angle from the peak intensity ratio can be applied to crystalline anisotropic particles. Crystalline anisotropic particles include, for example, aluminum flakes, silver nanodiscs, silver nanorods, and hexagonal boron nitride.

If the average tilt angle cannot be determined by X-ray diffraction, for example, if the anisotropic particles are made of an amorphous material such as glass, observation of the anisotropic particles can be used to determine the average tilt angle can be asked for.
In observing the anisotropic particles, the inclination angles of the major axes of 100 anisotropic particles are measured, and the average value of the inclination angles of 100 anisotropic particles is taken as the average inclination angle.
Observation of the anisotropic particles is performed by obtaining a cross-sectional image of the functional layer using a scanning electron microscope, extracting the image of the anisotropic particles in the functional layer by image analysis using a computer, and extracting pixels. The inclination angle of the long axis is measured to obtain the average inclination angle θa.
As described above, the average inclination angle θa is the average value of the inclination angles θ of the long axes of the anisotropic particles with respect to the back surface of the functional layer.

<Content of anisotropic particles>
The content of anisotropic particles is expressed in volume %.
As for the anisotropic particles, as described above, the content of the anisotropic particles in the functional layer is 40% by volume or more, and the content of the anisotropic particles 15 is preferably 45 to 65% by volume. .
The higher the content of the anisotropic particles, the higher the functions peculiar to the anisotropic particles, such as thermal conductivity and electrical conductivity. By setting the content of the anisotropic particles 15 within the above range, excellent properties such as thermal conductivity and electrical conductivity can be obtained in the laminate and the functional sheet.
When the anisotropic particle content is Cs, the anisotropic particle volume is Vs, and the functional layer volume is V, the anisotropic particle content Cs (% by volume) is Cs=Vs/ is V.

The volume V of the functional layer is expressed by the product of the thickness T of the functional layer and the surface area or the back surface area of the thermoplastic resin substrate S. That is, V=S×T.
The surface area S or the back surface area S of the thermoplastic resin substrate can be obtained from the size of the thermoplastic resin substrate.
Regarding the thickness T of the functional layer, a cross-sectional image of the functional layer is obtained using a scanning electron microscope, the distance corresponding to the thickness is measured at 5 points in the cross-sectional image of the functional layer, and the average of the 5 points is used. thickness of the active layer.
The volume Vs of the anisotropic particles is represented by the product of the particle diameter of the anisotropic particles and the thickness of the anisotropic particles.
The particle size of the anisotropic particles is measured by a laser diffraction scattering method as described later. Regarding the thickness of the anisotropic particles, a cross-sectional image of the functional layer containing the anisotropic particles was obtained using a scanning electron microscope, and the distance corresponding to the thickness of 30 anisotropic particles was measured. , the average value of 30 anisotropic grains is taken as the thickness of the anisotropic grains.

<Particle size>
The particle diameter of the anisotropic particles is the particle diameter, that is, the median diameter, which is the cumulative value of 50% of the volume-based particle size distribution measured by the laser diffraction scattering method.
When the particle diameter of the anisotropic particles 15 is B and the thickness of the functional layer 14 is T (see FIG. 2), it is preferable that B≦T.
If B≦T as described above, the orientation of the anisotropic particles 15 is maintained during pressure bonding. That is, it is possible to prevent the anisotropic particles 15 from collapsing. Moreover, even when pressure is applied during pressure bonding, if the anisotropic particles 15 are oriented in parallel as shown in FIG. 2, the anisotropic particles 15 are prevented from collapsing. The orientation of the anisotropic particles 15 is maintained even after pressing. This makes it possible to obtain properties such as excellent electrical conductivity and thermal conductivity.
If the thickness T of the functional layer is T<B, the anisotropic particles 15 may tilt obliquely during pressure bonding, resulting in a lack of stability in electrical and thermal conductivity.
The upper limit of the thickness T of the functional layer is appropriately determined depending on the content of the anisotropic particles, the application of the functional sheet, etc., and is not particularly limited.
When the functional sheet is an anisotropically conductive sheet, it becomes difficult to ensure conductivity if the anisotropic particles 15 are relatively larger than the line width of the line and space. Therefore, the particle diameter of the anisotropic particles 15 is preferably less than 10 μm, and when the line width is 5 μm, the particle diameter is about 1.3 μm.

(aspect ratio)
Aspect ratio is a parameter that characterizes the shape of anisotropic particles.
The aspect ratio is obtained as follows. First, the anisotropic particle powder was observed using a scanning electron microscope (SEM), the long axis and short axis of 30 anisotropic particles were measured, and the average value of the long axis and the short axis Calculate the average value of each. The ratio of the average value of the major axis to the average value of the minor axis is the aspect ratio. The anisotropic particles 15 have an aspect ratio of 3-100, preferably 5-50.
The shape of the plate-like anisotropic grains is not particularly limited with respect to the shape of the surface, and may be circular, quadrangular, pentagonal, hexagonal, or the like. Further, the anisotropic particles 15 may be scale-like, rod-like, needle-like, or fiber-like, in addition to the plate-like shape.

<Functional layer>
(binder)
The functional layer contains at least anisotropic particles and a binder. The anisotropic particles have been described above, and the binder will now be described.
The binder is preferably one that imparts bondability to the object to be connected.
The binder preferably exhibits fluidity at least when the thermoplastic resin substrate is shrunk.
The binder preferably exhibits fluidity in the temperature range of, for example, 50.degree. C. to 150.degree. C. and cures above 150.degree.
The binder preferably contains at least a curable compound.
The binder is preferably a component that constitutes an electrically insulating material after curing. Electrical insulation refers to electrical resistance of 10 ¹⁰ Ω·m or more.
Curable compounds include compounds that are cured by polymerization and/or cross-linking due to heat or UV light (ultraviolet light). That is, thermosetting compounds and photocurable compounds are included. These compounds may be polymers or monomers. The curable compound may be a mixture of two or more compounds (for example, main agent and curing agent).
Examples of thermosetting compounds include epoxy resins, silicone resins, phenol resins, polyimide resins, polyester resins, polyurethane resins, bismaleimide resins, melamine resins, phenoxy resins, and isocyanate resins, and these compounds. precursors and reaction intermediates for
For example, the thermosetting compound is an epoxy compound (preferably an epoxy compound having two or more epoxy groups) and a curing agent (e.g., a phenol compound (preferably a phenol compound having two or more phenolic hydroxyl groups) for obtaining an epoxy resin. , an amine compound, and/or an acid anhydride), or a semi-cured product (reaction intermediate) of the above mixture.
Examples of photocurable compounds include epoxy compounds and compounds having a carbon-carbon double bond (ethylenically unsaturated bond).
Among them, the curable compound is preferably a thermosetting compound because the adhesiveness with the object to be connected is higher, and the curable compound is a thermosetting compound because the insulation reliability is further improved and the chemical resistance is excellent. Epoxy resin, polyimide resin, Alternatively, precursors and reaction intermediates for obtaining these are preferred.
A curable compound may be used individually by 1 type, or may use 2 or more types together.
As for the binder in the functional layer, the curable compound described above is preferably present in an uncured or semi-cured state. The curable compound in a semi-cured state is a state in which the curing reaction of the curable compound is partially progressing, and further treatment (for example, heat treatment) leaves room for the further curing reaction to proceed. Intend to be left behind.
The binder content in the functional layer is preferably less than 60% by mass, more preferably 35 to 55% by mass.

The binder may contain components other than the curable compound.
For example, the functional layer may contain a polymerization initiator. Polymerization initiators include thermal polymerization initiators and photopolymerization initiators. Among them, a thermal cationic polymerization initiator is preferred. Photocationic polymerization initiators include aromatic diazonium salts, sulfonium salts, iodonium salts, phosphonium salts, benzoin tosylate, and o-nitrobenzyl tosylate.

Moreover, the binder may contain a curing accelerator. The curing accelerator can be appropriately determined depending on the type of curable compound. For example, when using an epoxy compound as a thermosetting compound, triphenylphosphine, 2-ethyl-4-methylimidazole, boron trifluoride amine complex, 1-benzyl-2-methylimidazole, and JP 2012-67225 Compounds described in paragraph 0052 of the publication are mentioned.

Additives contained in the binder include silane coupling agents, antioxidants, anti-migration agents, fillers, etc., in addition to the above.

The present invention is basically configured as described above. Although the method for producing a laminate, the method for producing a functional sheet, and the laminate according to the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various may of course be improved or changed.

The features of the present invention will be described more specifically with reference to examples below. Materials, reagents, amounts and ratios of substances, operations, etc. shown in the following examples can be changed as appropriate without departing from the gist of the present invention. Accordingly, the scope of the invention is not limited to the following examples.
In this example, the thermally conductive sheets of Examples 1 to 8 and Comparative Examples 1 and 2 were produced as functional sheets, the peak intensity ratio of the thermally conductive sheets was obtained to obtain the average inclination angle, and the thermal Conductivity was determined. The peak intensity ratio, average tilt angle and thermal conductivity are shown in Table 1 below. Examples 1 to 8 and Comparative Examples 1 and 2 are described below.

[Example 1]
In Example 1, tabular boron nitride particles (PT110 manufactured by Momentive, average particle size 45 μm, aspect ratio 23) were used as anisotropic particles, and a biaxially oriented polystyrene substrate (stock Tamiya Plaban, product number 70127, sheet thickness 0.4 mm, glass transition temperature 100° C.) was used.
In Example 1, 50.9 g of flat boron nitride particles (PT110 manufactured by Momentive, average particle size 45 μm, aspect ratio 23), epoxy compound (jER (registered trademark) YX4000 manufactured by Mitsubishi Chemical) 8.25 g, phenolic curing agent (AV Light BIR-PC manufactured by Asahi Organic Chemicals Co., Ltd.) 3.09 g, dispersant (BYK-106 manufactured by BYK Chemie Japan) 0.084 g, cyclopentanone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 32.5 g, and A coating composition was prepared by mixing 0.084 g of triphenylphosphine (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.). The content of the boron nitride particles in the solid content of the coating composition described above is 70% by volume in the state of the thermally conductive sheet.
The above-mentioned coating composition is applied onto a biaxially stretched polystyrene substrate using an applicator (clearance 300 μm), then heated at a temperature of 80 ° C. to dry, the coating corresponding to the functional layer, and the biaxial Laminates of oriented polystyrene substrates were prepared.
After cutting the laminated material into a size of 5 cm square, it was heated at a temperature of 120° C. for 30 minutes to shrink it to a size of 2.5 cm square.

As a result of analyzing the coating film of the laminated material after this shrinkage using the X-ray diffraction method, the peak intensity ratio (R = I _[002] / I _[100] ) of the anisotropic particles in the coating film was 6.1. and the average inclination angle θa of the boron nitride particles obtained from the peak intensity ratio was 55°.
The average inclination angle θa is the average value of the inclination angles θ of the plurality of anisotropic particles with respect to the back surface of the functional layer (coating film), and the above-mentioned average inclination angle θa formula θa=cos ⁻¹ { R/(R+2×α)} ^0.5 . For hexagonal boron nitride, α in the formula is 6.25.

The above-mentioned shrinkable laminated material is immersed in limonene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) for 6 hours to dissolve the biaxially stretched polystyrene base material, dried, and further cured by heating at a temperature of 180 ° C. for 90 minutes. to obtain a thermally conductive sheet having a thickness of 700 μm.
As a result of measuring the thermal conductivity of the thermally conductive sheet using the xenon flash method, the thermal conductivity of Example 1 was 3.3 W/mK. "LFA467" manufactured by NETZSCH was used for the measurement using the xenon flash method.

[Example 2]
In Example 2, a coating composition was prepared in the same manner as in Example 1, except that 32.7 g of flat boron nitride particles (PT110 manufactured by Momentive) were used as the anisotropic particles. The content of boron nitride particles in the solid content of this coating composition is 60% by volume in the state of the thermally conductive sheet. A coating film and a biaxially oriented polystyrene-based laminate, a shrunk laminate, and a thermally conductive sheet were obtained in the same manner as in Example 1, except that this coating composition was used.
_{[002 ]} /I _[100] ) was 3.7, and the average inclination angle θa of the boron nitride particles obtained from the peak intensity ratio was 61°.
FIG. 12 shows the analysis results of Example 2 by the X-ray diffraction method.
As a result of measuring the thermal conductivity of the thermally conductive sheet of Example 2 using the xenon flash method, the thermal conductivity of Example 2 was 3.7 W/mK.

[Example 3]
In Example 3, a coating composition was prepared in the same manner as in Example 1, except that 21.8 g of flat boron nitride particles (PT110 manufactured by Momentive) were used as the anisotropic particles. An oriented polystyrene-based laminate, a shrunk laminate, and a thermally conductive sheet were obtained.
_{[002 ]} /I _[100] ) was 4.9, and the average inclination angle θa of the boron nitride particles obtained from the peak intensity ratio was 58°.
As a result of measuring the thermal conductivity of the thermally conductive sheet of Example 3 using the xenon flash method, the thermal conductivity of Example 3 was 3.5 W/mK.

[Example 4]
In Example 4, a coating composition was prepared in the same manner as in Example 1, except that 14.5 g of flat boron nitride particles (PT110 manufactured by Momentive) were used as the anisotropic particles. An oriented polystyrene-based laminate, a shrunk laminate, and a thermally conductive sheet were obtained.
_{[002 ]} /I _[100] ) was 7.6, and the average inclination angle θa of the boron nitride particles obtained from the peak intensity ratio was 52°.
As a result of measuring the thermal conductivity of the thermally conductive sheet of Example 4 using the xenon flash method, the thermal conductivity of Example 4 was 2.8 W/mK.

[Example 5]
In Example 5, after cutting the laminate of the coating film and the biaxially oriented polystyrene base material into a size of 5 cm square, it was heated at a temperature of 120 ° C. for 5 minutes, except that it was shrunk to a size of 3.0 cm square. obtained a laminated material and a thermally conductive sheet which were shrunk in the same manner as in Example 1.
_{[002 ]} /I _[100] ) was 5.3, and the average inclination angle θa of the boron nitride particles obtained from the peak intensity ratio was 57°.
As a result of measuring the thermal conductivity of the thermally conductive sheet of Example 5 using the xenon flash method, the thermal conductivity of Example 5 was 3.4 W/mK.

[Example 6]
In Example 6, the laminated material of the coating film and the biaxially oriented polystyrene base material was cut into a size of 5 cm square, and then heated at 120 ° C. for 3.5 minutes to shrink to a size of 3.5 cm square. Except for this, a shrunk laminated material and a thermally conductive sheet were obtained in the same manner as in Example 1.
_{[002 ]} /I _[100] ) was 7.1, and the average inclination angle θa of the boron nitride particles obtained from the peak intensity ratio was 53°.
As a result of measuring the thermal conductivity of the thermally conductive sheet of Example 6 using the xenon flash method, the thermal conductivity of Example 6 was 3.1 W/mK.

[Example 7]
In Example 7, after cutting the laminate of the coating film and the biaxially oriented polystyrene base material into a size of 5 cm square, it was heated at a temperature of 120 ° C. for 2 minutes to shrink to a size of 4.0 cm square. obtained a laminated material and a thermally conductive sheet which were shrunk in the same manner as in Example 1.
_{[002 ]} /I _[100] ) was 8.8, and the average inclination angle θa of the boron nitride particles obtained from the peak intensity ratio was 50°.
As a result of measuring the thermal conductivity of the thermally conductive sheet of Example 7 using the xenon flash method, the thermal conductivity of Example 5 was 2.7 W/mK.

[Example 8]
In Example 8, the coating composition prepared in Example 2 was applied onto a biaxially stretched polystyrene substrate using an applicator (clearance of 300 μm), and then heated to a temperature of 80° C. to dry. A laminate of biaxially oriented polystyrene substrate was prepared. After cutting the above laminated material into a size of 5 cm square, in order to shrink it uniaxially, the two opposite sides were fixed with tape, and then heated at a temperature of 120 ° C. for 30 minutes to make the laminated material 4.5 cm × 2. .0 cm.
The above-mentioned shrinkable laminated material is immersed in limonene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) for 6 hours to dissolve the polystyrene base material, dried, and further cured by heating at a temperature of 180 ° C. for 90 minutes. A conductive sheet was obtained.
_{[002 ]} /I _[100] ) was 2.7, and the tilt angle obtained from the peak intensity ratio was 65°.
The thermal conductivity of the thermally conductive sheet of Example 8 was measured using the xenon flash method and found to be 3.9 W/mK.

[Comparative Example 1]
In Comparative Example 1, the coating composition of Example 2 was applied onto a release-treated polyethylene terephthalate substrate using an applicator (clearance of 300 μm), and then heated at a temperature of 80° C. to dry. A laminated material of a polyethylene terephthalate base material (hereinafter referred to as a PET base material) was produced. After cutting this laminated material into a size of 5 cm square, it was heated at a temperature of 120° C. for 30 minutes. In Comparative Example 1, the laminated material did not thermally shrink during heating and maintained the size of 5 cm square. In addition, in Comparative Example 1, since heat shrinkage was not performed, "-" is indicated in the column of heat shrinkage in Table 1.
In Comparative Example 1, as in Example 1, as a result of analyzing the coating film of the laminated material using the X-ray diffraction method, the peak intensity ratio of the laminated material of Comparative Example 1 (R = I _[002] / I _{[100 ]} ) was 287, and the tilt angle obtained from the peak intensity ratio was 12°. FIG. 13 shows the analysis results of Comparative Example 1 by the X-ray diffraction method. 12 and 13, the diffraction intensity at (100) in Comparative Example 1 is much smaller than that in Example 2. FIG.
After peeling off the release-treated PET substrate from the laminated material, it was cured by heating at a temperature of 180° C. for 90 minutes to obtain a thermally conductive sheet.
The thermal conductivity of the thermally conductive sheet of Comparative Example 1 was measured using the xenon flash method and found to be 1.5 W/mK.

[Comparative Example 2]
In Comparative Example 2, a coating composition was prepared in the same manner as in Example 1, except that 25.45 g of flat boron nitride particles (PT110 manufactured by Momentive) were used as the anisotropic particles. The content of boron nitride particles in the solid content of this coating composition is 35% by volume in the state of the thermally conductive sheet. A coating film, a laminated material, and a thermally conductive sheet were obtained in the same manner as in Comparative Example 1, except that this coating composition was used.
Also in Comparative Example 2, since the film was not heat-shrunk, "-" is indicated in the column of heat-shrinkage in Table 1.
In Comparative Example 2, as in Example 1, the coating film of the laminated material was analyzed using the X-ray diffraction method. As a result, the peak intensity ratio (R = I _[002] / I _{[100 ]} ) was 498, and the tilt angle obtained from the peak intensity ratio was 9°.
The thermal conductivity of the thermally conductive sheet of Comparative Example 2 was measured using the xenon flash method and found to be 0.6 W/mK.

As shown in Table 1, Examples 1-8 can increase the average tilt angle compared to Comparative Examples 1-2. As a result, Examples 1 to 8 had higher thermal conductivity than Comparative Examples 1 and 2, and had excellent performance as a thermally conductive sheet.
From Examples 1 to 8, uniaxial thermal contraction was able to increase the average tilt angle, and as a result, the thermal conductivity was increased. Thus, uniaxial heat shrinkage was superior as a manufacturing method.
Moreover, from Examples 2 and 5 to 7, the larger the shrinkage ratio, the larger the average inclination angle, and as a result, the higher the thermal conductivity.

REFERENCE SIGNS LIST 10 laminate 12 substrate 14 functional layer 14a, 15a, 40a front surface 14b rear surface 15 anisotropic particle 16 binder 18 release layer 20 functional sheet 30, 31 electronic device 32, 36 semiconductor element 34 heat sink 35 terminal 40 thermoplastic resin Substrate 42 Coating composition 44 Laminated material D Film thickness direction Da Major axis Dc Minor axis Dt Lamination direction P _L surface T Thickness θ Tilt angle

Claims (8)

A step of laminating a heat-shrinkable thermoplastic resin substrate and a functional layer containing a plurality of anisotropic particles and a binder;
The thermoplastic resin substrate on which the functional layer is laminated is heated to a temperature equal to or higher than the glass transition temperature of the thermoplastic resin substrate to shrink the thermoplastic resin substrate, and the plurality of anisotropic and orienting the long axes of the particles in the film thickness direction of the functional layer. The step of laminating the thermoplastic resin substrate and the functional layer includes
2. The method for producing a laminate according to claim 1, comprising a step of applying a coating composition containing said plurality of anisotropic particles and said binder onto said heat-shrinkable thermoplastic resin substrate. The step of orienting the long axes of the plurality of anisotropic particles in the film thickness direction of the functional layer includes heating the thermoplastic resin substrate to a temperature equal to or higher than the glass transition temperature, and 3. The method for producing a laminate according to claim 1, wherein the substrate is uniaxially shrunk. A step of laminating a heat-shrinkable thermoplastic resin substrate and a functional layer containing a plurality of anisotropic particles and a binder to form a laminated material;
The laminated material is heated to a temperature equal to or higher than the glass transition temperature of the thermoplastic resin substrate to shrink the thermoplastic resin substrate so that the major axes of the plurality of anisotropic particles are aligned with the film of the functional layer. Orienting in the thickness direction;
and removing the thermoplastic resin base material after shrinkage from the laminated material. The step of forming the laminated material by laminating the thermoplastic resin base material and the functional layer includes:
5. The method for producing a functional sheet according to claim 4, comprising applying a coating composition containing the plurality of anisotropic particles and the binder onto the heat-shrinkable thermoplastic resin substrate. orienting the long axes of the plurality of anisotropic particles in the film thickness direction of the functional layer,
6. Manufacture of the functional sheet according to claim 4 or 5, wherein the laminated material is heated to a temperature equal to or higher than the glass transition temperature of the thermoplastic resin substrate to uniaxially shrink the thermoplastic resin substrate. Method. Any one of claims 4 to 6, wherein the step of removing the thermoplastic resin base material after shrinkage from the laminated material is a step of immersing the laminated material in a solvent to dissolve the thermoplastic resin base material. The method for producing the functional sheet according to 1. The functionality according to any one of claims 4 to 6, wherein the step of removing the thermoplastic resin substrate after shrinkage from the laminate is a step of peeling the thermoplastic resin substrate from the laminate. Sheet manufacturing method.

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