Thermally conductive sheet and method for manufacturing the same

Abstract

To provide a thermal conductive sheet that exhibits good thermal conductivity in the thickness direction and is easy to handle on a mechanized line.SOLUTION: A thermal conductive sheet formed by joining multiple strips in parallel contains a resin and a thermally conductive filler, and the flat area ratio is 70% or more, and on at least one main surface, the number of chips having a size of 0.04 mm2 or more and 4.0 mm2 or less adhering per 225 cm2 of the main surface in plan view is 1.0 or more and 20.0 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a thermally conductive sheet and a method for manufacturing the thermally conductive sheet. [Background technology]

[0002] In recent years, the amount of heat generated by electronic components such as plasma display panels (PDPs) and integrated circuit (IC) chips has increased as their performance has improved. As a result, electronic devices that use these components need to take measures to prevent malfunctions caused by temperature increases in the electronic components.

[0003] To prevent malfunctions caused by temperature rise in electronic components, a common method is to promote heat dissipation by attaching a heat sink, heat sink plate, heat sink fin, or other heat sink made of metal to the heat-generating body of the electronic component.When using a heat sink, the heat source and the heat sink are closely attached with a sheet-like member with high thermal conductivity (thermal conduction sheet) in between in order to efficiently transfer heat from the heat source to the heat sink.

[0004] Therefore, a thermally conductive sheet that is sandwiched between a heat generating element and a heat dissipating element is required to exhibit excellent thermal conductivity in the thickness direction.

[0005] For example, in Patent Documents 1 and 2, a thermally conductive sheet is produced by slicing a laminate of primary sheets containing a resin and a thermally conductive filler along a plane parallel to the lamination direction. The thermally conductive sheet thus obtained has a structure in which multiple strips are joined in parallel, and the thermally conductive filler is oriented in the thickness direction, so that it can exhibit good thermal conductivity in the thickness direction. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-5594 [Patent Document 2] Japanese Patent Application Publication No. 2018-89733 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, the manufacturing and inspection lines for thermal conductive sheets have become increasingly mechanized. For example, a pickup arm is used to transport the thermal conductive sheet, using the suction force of multiple suction holes to hold the object. Furthermore, the visual inspection of thermal conductive sheets is becoming increasingly automated, using images of the object captured by a line camera. However, conventional thermal conductive sheets can fall or peel off when transported by a pickup arm. Also, when capturing images of conventional thermal conductive sheets using a line camera, it can take time to adjust the focus, and sometimes the image cannot be captured clearly enough for visual inspection due to poor focus, which can reduce the efficiency of the inspection. That is, conventional thermally conductive sheets have been required to exhibit good thermal conductivity in the thickness direction while also being easy to handle on mechanized production lines. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to achieve the above-mentioned object. Here, the inventors focused on the chips that may be generated during the manufacture of a thermally conductive sheet formed by joining multiple strips in parallel, and the shape of the thermally conductive sheet. The inventors discovered that if the number of chips per predetermined area of ​​the main surface of the thermally conductive sheet is within a predetermined range and the flat area ratio of the thermally conductive sheet is equal to or greater than a predetermined value, the thermally conductive sheet exhibits good thermal conductivity in the thickness direction (hereinafter sometimes abbreviated as "thermal conductivity") while being easy to handle on a mechanized production line. Furthermore, the present inventors discovered that the above-mentioned thermally conductive sheet can be efficiently manufactured using a predetermined manufacturing method, thereby completing the present invention.

[0009] That is, the present invention has an object to advantageously solve the above-mentioned problems, and the thermally conductive sheet of the present invention is a thermally conductive sheet formed by joining a plurality of strips in parallel, the thermally conductive sheet containing a resin and a thermally conductive filler, and having a flat portion area ratio of 70% or more, and at least one of the main surfaces having a planar area of ​​225 cm 2 The size of the contact point is 0.04 mm 2 Over 4.0mm 2 The thermal conductive sheet is characterized in that the number of chips is 1.0 or more and 20.0 or less. A thermal conductive sheet having such properties can exhibit excellent thermal conductivity in the thickness direction. Furthermore, the thermal conductive sheet is easy to handle in mechanized production lines. Specifically, the thermal conductive sheet is sufficiently prevented from falling or peeling when transported by a pickup arm, and the focus can be quickly adjusted when capturing images with a line camera, allowing for efficient visual inspection.

[0010] In this specification, the "flat area ratio" refers to the ratio of the flat area of ​​a thermal conductive sheet to the area of ​​the main surface (one of the main surfaces) of the thermal conductive sheet, and can be measured using the method described in the examples. In this specification, the "main surface" of a thermally conductive sheet means the surface of the thermally conductive sheet having the largest area and the surface opposite to the largest surface, and the areas of the two main surfaces are usually substantially equal. In this specification, "chips" refer to minute objects consisting of at least one of the components contained in the thermally conductive sheet. For example, the chips contain resin and / or thermally conductive filler. In one embodiment of the present invention, the chips are composed only of resin and / or thermally conductive filler. Note that chips are generated when a laminate of primary sheets containing resin and thermally conductive filler is sliced ​​to produce a thermally conductive sheet. However, the chips are not limited to this, as long as they adhere to the main surface of the thermally conductive sheet and are composed of at least one of the components contained in the thermally conductive sheet as described above. In this specification, the "planar area of ​​the main surface of 225 cm2" of the thermal conductive sheet 2 The size of the contact point is 0.04 mm 2Over 4.0mm 2 The number of chips that are equal to or less than the specified area (hereinafter, sometimes abbreviated as "number of chips per specified area") can be measured using the method described in the Examples. In this specification, the "size" of chips can be measured using the method described in the Examples.

[0011] In the thermally conductive sheet of the present invention, the volume fraction of the thermally conductive filler is preferably 30% by volume or more and 45% by volume or less. If the volume fraction of the thermally conductive filler is within the above range, the thermal conductivity of the thermally conductive sheet and its ease of handling in mechanized production lines can be further improved. In this specification, the "volume fraction of the thermally conductive filler" can be measured using the method described in the examples.

[0012] In the thermally conductive sheet of the present invention, the thermally conductive filler preferably has a volume average particle diameter of 150 μm or less. If the volume average particle diameter of the thermally conductive filler is equal to or less than the above value, the thermal conductivity of the thermally conductive sheet can be further improved. In this specification, the "volume average particle diameter of the thermally conductive filler" can be measured in accordance with JIS Z8825, and refers to the particle diameter at which the cumulative volume calculated from the smallest diameter side is 50% in the particle size distribution (volume basis) measured by laser diffraction.

[0013] The present invention also aims to advantageously solve the above-mentioned problems, and provides a method for producing a thermally conductive sheet, comprising the step of slicing a laminate of primary sheets containing a resin and a thermally conductive filler using a slicing mechanism along a plane parallel to the lamination direction of the laminate to obtain a thermally conductive sheet formed by joining a plurality of strips in parallel, wherein the slicing mechanism comprises a support base having a sliding surface, a flank surface, a rake surface, and a cutting edge formed at an intersection angle between the flank surface and the rake surface, the cutting edge being disposed so as to protrude from the sliding surface, a gap formed in the support base along the rake surface through which sliced ​​pieces cut from the laminate can pass by contacting with the cutting edge, and The method for producing a thermally conductive sheet according to the present invention includes a sliding plate disposed substantially perpendicular to the rake face and capable of receiving the slices that have passed through the gap, the slicing is performed by pressing the side surface of the laminate against the sliding plate while sliding the laminate so that the end surface of the laminate in the laminate direction becomes the main slicing surface and bringing it into contact with the blade, and the slices cut from the laminate are collected by sliding them along the sliding plate, and when the laminate and the slicing mechanism are viewed from above the sliding plate, the absolute value of the difference between the angle α from the laminate direction to the extension direction of the cutting edge of the blade and the angle β from the laminate direction to the extension direction of the sliding plate is between 0° and 15°.

[0014] In this specification, the "flank" of a blade means the surface on the side along which the laminate, a portion of which has been sliced, advances, and the "scooping" surface of a blade means the surface on the side along which the portion (slice piece) cut from the laminate by slicing advances. In this specification, "substantially perpendicular" means that the angle formed between one side and the other side is within the range of 90±20°. In this specification, the "end surface in the stacking direction" of a laminate means the top and bottom surfaces (or one of them) located at the ends in the stacking direction of a rectangular parallelepiped-shaped laminate formed by stacking multiple primary sheets, and the "side surface in the stacking direction" means the four surfaces (or any of them) other than the end surface in the stacking direction. In this specification, the "main slicing surface" of a laminate means the surface that comes into contact with the cutting edge when slicing of the laminate begins, and that has the longest length in the extension direction of the cutting edge that comes into contact with the surface until one slicing is completed. In this specification, "angle α from the stacking direction of the laminate to the direction of extension of the cutting edge of the blade" refers to the rotation angle when the laminate and slicing mechanism are viewed in a plan view from vertically above the slide surface during slicing, where the stacking direction line is rotated around the point where a line parallel to the stacking direction of the laminate (stacking direction line) intersects with a line extending in the direction of extension of the cutting edge (cutting edge line) until the stacking direction line overlaps with the cutting edge line, and can be in the range of 0°≦α≦90°. Note that when the two lines are parallel, α=0°, and when the two lines are perpendicular, α=90°. In this specification, "angle β from the stacking direction of the stack to the extension direction of the sliding plate" refers to the rotation angle when the stack and the slicing mechanism are viewed in a plane perpendicular to the slide surface during slicing, where the stacking direction line is rotated in the same direction as the angle α, centered on the point where a line parallel to the stacking direction of the stack (stacking direction line) intersects with a line extending in the extension direction of the sliding plate (sliding plate line), until the stacking direction line overlaps with the sliding plate line, and can be in the range of 0°≦β<180°. Note that when the two lines are parallel, β=0°, and when the two lines are perpendicular, β=90°. In this specification, the "absolute value of the difference between the angle α from the stacking direction of the laminate to the extension direction of the cutting edge of the blade and the angle β from the stacking direction of the laminate to the extension direction of the sliding plate" may be abbreviated as "|α-β|". Note that a "rectangular prism" is a three-dimensional shape with six rectangular and / or square faces, but in this specification, a "rectangular prism" is defined as any shape whose overall silhouette is a rectangular prism, and includes shapes with rounded corners.

[0015] In the method for producing a thermally conductive sheet of the present invention, the angle α is preferably 60° or more and 75° or less. If the angle α is 60° or more and 75° or less, the amount of chips generated by slicing can be sufficiently reduced and the thermal conductivity of the thermally conductive sheet can be further improved.

[0016] In the method for producing a thermally conductive sheet of the present invention, the coefficient of static friction of the surface of the sliding plate that comes into contact with the sliced ​​pieces cut out from the laminate is preferably 0.4 or less, so that the sliced ​​pieces cut out from the laminate can slide smoothly along the sliding plate. In this specification, the "static friction coefficient" can be measured using the method described in the examples. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a thermally conductive sheet that can exhibit good thermal conductivity in the thickness direction and is easy to handle on a mechanized line, and a method for manufacturing the thermally conductive sheet. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view showing an example of a thermally conductive sheet according to the present invention. [Figure 2] FIG. 2 is a perspective view showing an example of the positional relationship between a laminate and a blade when the laminate is sliced ​​by the method for producing a thermally conductive sheet according to the present invention. [Figure 3] 1 is an explanatory view (side view) showing a process for producing a thermally conductive sheet using an example of a method for producing a thermally conductive sheet according to the present invention. [Figure 4] FIG. 2 is a plan view showing a state in which a laminate is sliced ​​using the method for manufacturing a thermally conductive sheet according to an embodiment of the present invention. [Figure 5] FIG. 10 is a plan view showing how a laminate is sliced ​​using a method for manufacturing a thermally conductive sheet according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail. Here, the thermally conductive sheet of the present invention is used by being sandwiched between a heat generating element such as an electronic component and a heat dissipating element such as a metal heat sink, heat sink plate, or heat dissipating fin, and can be manufactured, for example, using the manufacturing method of the thermally conductive sheet of the present invention.

[0020] (thermal conductive sheet) The thermally conductive sheet of the present invention is formed by joining multiple strips in parallel. For example, the thermally conductive sheet 1 in Fig. 1 is formed by joining multiple adjacent strips 2 together at their longitudinal sides. While Fig. 1 shows a case where the multiple strips 2 have approximately the same width, the multiple strips 2 may have different widths. Furthermore, the multiple strips 2 may have the same composition or different compositions. The total number of strips constituting the thermally conductive sheet is not particularly limited, and may be, for example, 30 or more and 300 or less.

[0021] <Composition of the thermal conductive sheet> The thermally conductive sheet includes a resin and a thermally conductive filler, and may further include optional additives.

[0022] <<Resin>> Here, the resin may be at least one of a resin that is liquid at room temperature and atmospheric pressure, and a resin that is solid at room temperature and atmospheric pressure. In this specification, "room temperature" refers to 23°C, and "atmospheric pressure" refers to 1 atm (absolute pressure).

[0023] Examples of resins that are liquid at room temperature and normal pressure include thermoplastic resins that are liquid at room temperature and normal pressure, and thermosetting resins that are liquid at room temperature and normal pressure. Examples of thermoplastic resins that are liquid at room temperature and normal pressure include acrylic resins, epoxy resins, silicone resins, and fluororesins. Furthermore, examples of thermosetting resins that are liquid at room temperature and normal pressure include natural rubber; butadiene rubber; isoprene rubber; nitrile rubber; hydrogenated nitrile rubber; chloroprene rubber; ethylene propylene rubber; chlorinated polyethylene; chlorosulfonated polyethylene; butyl rubber; halogenated butyl rubber; polyisobutylene rubber; epoxy resin; polyimide resin; bismaleimide resin; benzocyclobutene resin; phenolic resin; unsaturated polyester; diallyl phthalate resin; polyimide silicone resin; polyurethane; thermosetting polyphenylene ether; and thermosetting modified polyphenylene ether.

[0024] Examples of resins that are solid at room temperature and normal pressure include thermoplastic resins that are solid at room temperature and normal pressure, and thermosetting resins that are solid at room temperature and normal pressure. Examples of thermoplastic resins that are solid at room temperature and pressure include acrylic resins such as poly(2-ethylhexyl acrylate), copolymers of acrylic acid and 2-ethylhexyl acrylate, polymethacrylic acid or its ester, and polyacrylic acid or its ester; silicone resins; fluororesins; polyethylene; polypropylene; ethylene-propylene copolymers; polymethylpentene; polyvinyl chloride; polyvinylidene chloride; polyvinyl acetate; ethylene-vinyl acetate copolymers; polyvinyl alcohol; polyacetal; polyethylene terephthalate; polybutylene terephthalate; polyethylene naphthalate; poly Examples include styrene; polyacrylonitrile; styrene-acrylonitrile copolymer; acrylonitrile-butadiene-styrene copolymer (ABS resin); styrene-butadiene block copolymer or hydrogenated product thereof; styrene-isoprene block copolymer or hydrogenated product thereof; polyphenylene ether; modified polyphenylene ether; aliphatic polyamides; aromatic polyamides; polyamideimide; polycarbonate; polyphenylene sulfide; polysulfone; polyethersulfone; polyethernitrile; polyetherketone; polyketone; polyurethane; liquid crystal polymer; ionomer; and the like. Furthermore, examples of thermosetting resins that are solid at room temperature and normal pressure include natural rubber; butadiene rubber; isoprene rubber; nitrile rubber; hydrogenated nitrile rubber; chloroprene rubber; ethylene propylene rubber; chlorinated polyethylene; chlorosulfonated polyethylene; butyl rubber; halogenated butyl rubber; polyisobutylene rubber; epoxy resin; polyimide resin; bismaleimide resin; benzocyclobutene resin; phenolic resin; unsaturated polyester; diallyl phthalate resin; polyimide silicone resin; polyurethane; thermosetting polyphenylene ether; and thermosetting modified polyphenylene ether. Among these, it is preferable to use, as the resin, a fluororesin that is liquid at room temperature and normal pressure, and a fluororesin that is solid at room temperature and normal pressure. The above-mentioned resins may be used alone or in combination of two or more.

[0025] <<Thermal conductive filler>> The thermally conductive filler is not particularly limited, and examples thereof include particulate materials such as alumina particles, zinc oxide particles, boron nitride particles, aluminum nitride particles, silicon nitride particles, silicon carbide particles, magnesium oxide particles, and particulate carbon materials (e.g., artificial graphite, scaly graphite, exfoliated graphite, natural graphite, acid-treated graphite, expandable graphite, expanded graphite, carbon black, etc.), as well as fibrous materials such as carbon nanotubes (hereinafter sometimes referred to as "CNTs"), vapor-grown carbon fibers, carbon fibers obtained by carbonizing organic fibers, and cut products thereof. Among these, the thermally conductive filler is preferably at least one selected from the group consisting of scaly particulate materials such as boron nitride particles, artificial graphite, flake graphite, expandable graphite, and expanded graphite; and fibrous carbon nanomaterials such as CNTs; more preferably, scaly particulate materials are used, even more preferably, anisotropic graphite such as flake graphite and expanded graphite is used, and particularly preferably, expanded graphite is used. The use of these thermally conductive fillers can further increase the thermal conductivity of the thermally conductive sheet. The thermally conductive filler may be used alone or in combination of two or more kinds.

[0026] The thermally conductive filler preferably has a volume average particle diameter of 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more, and preferably 150 μm or less, more preferably 120 μm or less, and even more preferably 90 μm or less. If the volume average particle diameter of the thermally conductive filler is 150 μm or less, the size of chips generated when slicing the laminate can be prevented from becoming excessively large. Furthermore, if the volume average particle diameter of the thermally conductive filler is within the above range, the thermal conductivity of the thermally conductive sheet can be further improved.

[0027] The volume fraction of the thermally conductive filler in the thermally conductive sheet is preferably 30% by volume or more, more preferably 35% by volume or more, even more preferably 40% by volume or more, and preferably 45% by volume or less, and more preferably 43% by volume or less, based on the total volume of the thermally conductive sheet being 100% by volume. If the volume fraction of the thermally conductive filler in the thermally conductive sheet is 30% by volume or more, the size of chips generated when slicing the laminate can be prevented from becoming excessively large. On the other hand, if the volume fraction of the thermally conductive filler in the thermally conductive sheet is 45% by volume or less, the amount of chips generated when slicing the laminate can be reduced. Furthermore, if the volume fraction of the thermally conductive filler in the thermally conductive sheet is within the above-mentioned range, the thermal conductivity of the thermally conductive sheet can be further improved.

[0028] <<Additives>> Additives that can be optionally contained in the thermal conductive sheet are not particularly limited, and examples thereof include flame retardants, plasticizers, toughness improvers, moisture absorbents, adhesion improvers, wettability improvers, and ion trapping agents. The additives may be used alone or in combination of two or more.

[0029] <Thermal Conduction Sheet Properties> As described above, the thermally conductive sheet must have a flat area ratio equal to or greater than a predetermined value, and the number of chips per predetermined area must be within a predetermined range.

[0030] <<Flat area ratio>> The thermal conductive sheet of the present invention must have a flat area ratio of 70% or more, preferably 75% or more, and more preferably 80% or more. If the flat area ratio is less than 70%, it will not be possible to prevent the sheet from falling or peeling off during transport by a pickup arm, which will impair its handleability in mechanized production lines. The upper limit of the flat area ratio is not particularly limited and can be 100%. The flat portion area ratio can be increased by changing the manufacturing conditions of the thermal conductive sheet to suppress curling, etc. The manufacturing method of the thermal conductive sheet of the present invention described below is preferably used to manufacture a thermal conductive sheet with suppressed curling.

[0031] <<Number of chips per specified area>> The thermally conductive sheet of the present invention has a planar area of ​​225 cm when observed from at least one of its main surfaces. 2 The size of the contact point is 0.04 mm 2 Over 4.0mm 2 The number of chips that is equal to or less than 1.0 must be 1.0 or more and 20.0 or less, preferably 15.0 or less, more preferably 10.0 or less, and even more preferably 8.0 or less. The inventors' research has revealed that the presence of chips on the main surface of a thermally conductive sheet allows the chips to be focused on during imaging by a line camera, enabling efficient focus adjustment. On the other hand, it has also been revealed that an excessive number of chips on the main surface of a thermally conductive sheet impairs thermal conductivity in the thickness direction, presumably due to variations in the thickness of the thermally conductive sheet. That is, by having a chip count of 1.0 or more per given area, the thermally conductive sheet of the present invention allows efficient focus adjustment during imaging by a line camera, ensuring ease of handling in mechanized production lines. On the other hand, by having a chip count of 20.0 or less per given area, the thermal conductivity of the thermally conductive sheet in the thickness direction is ensured. The number of chips per given area can be efficiently controlled within the above-mentioned range by using the manufacturing method of the thermally conductive sheet of the present invention described below. Also, the number of chips per given area can be reduced by decreasing the volume fraction of the thermally conductive filler contained in the laminate (i.e., the volume fraction of the thermally conductive filler contained in the thermally conductive sheet) or increasing the volume fraction of the resin contained in the laminate (i.e., the volume fraction of the resin contained in the thermally conductive sheet).

[0032] The chips may have any shape, such as fibers, powder, or chips. The thermal conductive sheet of the present invention is not particularly limited as long as it satisfies the above-mentioned number of chips per predetermined area, and the size is 0.04 mm 2 Chips less than 4.0mm in size 2 However, in order to further improve the thermal conductivity of the thermal conductive sheet and to improve the appearance, chips of less than 0.04 mm in size may be attached to the main surface. 2 Chips less than 4.0mm in size 2 In other words, from the viewpoint of further improving the thermal conductivity of the thermal conductive sheet while improving the appearance, it is preferable that all chips adhering to the main surfaces are smaller than 0.04 mm in size. 2 Over 4.0mm 2 It is preferable that the size of all chips adhering to the main surface is within the range of 0.04 mm. 2 Over 2.0mm 2 It is preferable that the range is within the following range: 0.04 mm 2 Over 0.8mm 2 It is more preferable that the content is within the following range.

[0033] The size of the chips can be reduced, for example, by increasing the volume fraction of the thermally conductive filler contained in the laminate (i.e., the volume fraction of the thermally conductive filler contained in the thermally conductive sheet) or by reducing the volume fraction of the resin contained in the laminate (i.e., the volume fraction of the resin contained in the thermally conductive sheet).The size of the chips can also be reduced, for example, by reducing the volume average particle diameter of the thermally conductive filler contained in the laminate (i.e., the volume average particle diameter of the thermally conductive filler contained in the thermally conductive sheet).

[0034] The thermally conductive sheet of the present invention may satisfy the above-mentioned condition for the number of chips per specified area on both main surfaces, or may satisfy the above-mentioned condition for the number of chips per specified area on one main surface but not on the other main surface. From the viewpoint of further improving the thermal conductivity in the thickness direction of the thermally conductive sheet, it is preferable that the above-mentioned condition for the number of chips per specified area on one main surface is satisfied, and the number of chips per specified area on the other main surface is less than 1.0, and more preferably 0 (undetectable).

[0035] <<Other properties>> The planar area of ​​the thermally conductive sheet is not particularly limited and can be adjusted appropriately depending on the application of the thermally conductive sheet. The thermally conductive sheet preferably has an average thickness of 1000 μm or less, more preferably 500 μm or less, even more preferably 150 μm or less, and preferably 20 μm or more, more preferably 50 μm or more, and even more preferably 80 μm or more. An average thickness of 1000 μm or less allows for greater freedom in placement of the thermally conductive sheet within a device when mounted. Furthermore, an average thickness of 20 μm or more ensures sufficient strength of the thermally conductive sheet.

[0036] (Method of manufacturing thermal conductive sheets) The method for manufacturing a thermally conductive sheet of the present invention is used to manufacture a thermally conductive sheet that contains at least a resin and a thermally conductive filler and has a structure in which a plurality of strips are joined in parallel. In particular, the method for manufacturing a thermally conductive sheet of the present invention is preferably used to manufacture the thermally conductive sheet of the present invention described above.

[0037] The method for manufacturing a thermally conductive sheet of the present invention includes a step of slicing a laminate of primary sheets containing a resin and a thermally conductive filler using a slicing mechanism in a plane parallel to the stacking direction of the laminate, thereby obtaining a thermally conductive sheet comprising multiple strips joined in parallel.

[0038] <Laminate> The laminate that is the material for the thermally conductive sheet is formed by laminating a plurality of primary sheets that contain a resin and a thermally conductive filler, and optionally further contain additives. The resin, thermally conductive filler, and additives that can be used are the same as those in the thermally conductive sheet of the present invention described above, and the preferred embodiments are also the same as those in the thermally conductive sheet of the present invention described above, so explanations will be omitted below.

[0039] The laminate has a structure in which a plurality of primary sheets are laminated as described above. 2, the laminate 10 has a total of six faces, including a top face 11 and a bottom face 12 (stacking direction end faces) which are the main faces of the primary sheets located at the ends of the stacking direction D, and four stacking direction side faces 13 to 16 which are formed by the side faces of the primary sheets stacked in the stacking direction D. Here, the top face 11 and the bottom face 12 which are the stacking direction end faces are equal faces, and each of the stacking direction side faces 13 to 16 are equal faces. In FIG. 2, an example is shown in which the laminated body is a cube, but the scope of the present invention is not limited to this.

[0040] The laminate can be obtained by laminating, folding or winding a primary sheet obtained by molding a resin composition containing a resin and a thermally conductive filler, and optionally further containing additives, into a sheet. In a laminate formed by laminating primary sheets, the adhesive strength between the surfaces of the primary sheets is usually sufficient due to the pressure applied when laminating the primary sheets. However, if the adhesive strength is insufficient or if it is necessary to sufficiently prevent delamination of the laminate, the lamination may be performed with the surfaces of the primary sheets slightly dissolved in a solvent, or with an adhesive applied to the surfaces of the primary sheets or with an adhesive layer provided on the surfaces of the primary sheets, or the laminate formed by laminating the primary sheets may be further pressed in the lamination direction.

[0041] <Slice mechanism> The slicing mechanism must include at least a support base, a blade whose cutting edge protrudes from the sliding surface of the support base, a gap formed in the support base along the cutting surface of the blade, and a sliding plate that is approximately perpendicular to the cutting surface of the blade and is capable of receiving slices that pass through the gap.

[0042] 3(a) to 3(c), an example of a slicing mechanism includes a support base 20 having a slide surface 21, a blade 30 having a rake face 31, a flank 32, and a cutting edge formed by the intersection angle of the rake face 31 and the flank 32, a gap 40 provided adjacent to the rake face, and a slide plate 50 arranged approximately perpendicular to the rake face 31 of the blade 30 and capable of receiving sliced ​​pieces 60 produced by slicing. In the example of FIG. 3, the blade 30 is fixed to the support base 20, and the slide plate 50 is fixed to the support base 20 via the blade 30. As shown in Fig. 3(b), slices 60 cut out from the laminate 10 during slicing pass through a gap 40 provided on the rake face 31 side of the blade 30. The slices that have passed through the gap 40 then reach a sliding plate 50 as shown in Fig. 3(c), slide (slide down) on the surface of the sliding plate 50, and are delivered to, for example, a collection unit (not shown) that has been prepared in advance.

[0043] Here, the coefficient of static friction of the surface of the sliding plate that comes into contact with the sliced ​​pieces cut from the laminate is preferably 0.4 or less, more preferably 0.2 or less, so that the sliced ​​pieces cut from the laminate can slide smoothly along the sliding plate. The shape of the sliding plate is not particularly limited, but is preferably rectangular when viewed from above from the sliding surface side of the slicing mechanism, and more preferably has a rectangular shape with the long side extending parallel to the cutting surface of the blade and the short side extending perpendicular to the cutting surface of the blade. In this specification, the term "rectangle" also includes shapes with rounded corners.

[0044] As described in Patent Document 1 (JP 2021-5594 A), the slicing mechanism may include a guide member disposed opposite the rake face of the blade, and an auxiliary guide member disposed in contact with the rake face of the blade and facing the guide member. By providing the slicing mechanism with a guide member, or by providing the slicing mechanism with a guide member and an auxiliary guide member, curling of the thermally conductive sheet can be suppressed. However, it has become clear that adopting such a configuration can cause slices to become clogged in the gap between the guide member and the rake face (or between the guide member and the auxiliary guide member if the rake face is equipped with an auxiliary guide member), resulting in a problem of reduced yield of the thermally conductive sheet. Therefore, from the perspective of improving yield, it is preferable that the slicing mechanism used in the thermally conductive sheet manufacturing method of the present invention does not include both the guide member and the auxiliary guide member described above. In addition, by using the thermally conductive sheet manufacturing method of the present invention, it is possible to efficiently manufacture thermally conductive sheets in which curling is suppressed and a flat area ratio is ensured to be equal to or greater than a predetermined value, even without using the guide member and auxiliary guide member described above.

[0045] <Slice> In the method for manufacturing a thermal conductive sheet of the present invention, when slicing using the above-mentioned slicing mechanism, it is necessary to adjust the positions of the blade and the laminate so that the end surface in the stacking direction (not the side surface in the stacking direction) becomes the main slicing surface. In the past, when a thermally conductive sheet was obtained by bringing a laminate into contact with a blade on a support table, the side surface in the stacking direction was used as the main slicing surface in order to reduce the impact on the blade. However, the inventors' investigations revealed that using the side surface in the stacking direction as the main slicing surface placed a load on the end surface in the stacking direction, resulting in excessive chipping. This point will be explained using FIG. 2 as an example. In FIG. 2, assume that the laminate 10 is slid in a direction perpendicular to the stacking direction D, and sliced ​​with the main slice surface as the stacking direction side surface 13. In this case, the greatest load is placed on the bottom surface 12 (the stacking direction end surface), which is adjacent to the main slice surface and is the surface at the end of the cutting. It is presumed that fraying easily occurs on the bottom surface 12 because a structure is formed in which the thermally conductive filler oriented in a direction perpendicular to the stacking direction D overlaps. Many of these frayed pieces fall onto the sliced ​​pieces from the stacking direction side surface 16 and adhere in large quantities as chips, exceeding the upper limit of the number of chips per given area for the thermally conductive sheet of the present invention described above. 2, suppose that the laminate 10 is slid in the stacking direction D and sliced ​​with the main slice surface being the top surface 11, which is the end surface in the stacking direction. In this case, the greatest load is placed on the side surface 13 in the stacking direction, which is adjacent to the main slice surface and is the surface at the end of the cut. However, according to the inventors' research, it has become clear that the side surface in the stacking direction is less likely to fray than the end surface in the stacking direction, and the number of chips that fall onto the sliced ​​piece can be significantly reduced. Based on the above findings, the method for manufacturing a thermal conductive sheet of the present invention slices the laminate so that the end faces in the stacking direction become the main slice surfaces. This slicing method makes it easy to control the number of chips per given area within the above-mentioned range.

[0046] Furthermore, when slicing, when the laminate and slicing mechanism are viewed in a plane from the slide surface side, the absolute value of the difference between the angle α from the stacking direction of the laminate to the extension direction of the cutting edge of the blade and the angle β from the stacking direction of the laminate to the extension direction of the slide plate (|α-β|) must be greater than or equal to 0° and less than or equal to 15°.

[0047] When |α-β| is between 0° and 15°, the sliding plate can effectively receive the slices produced by slicing when the laminate comes into contact with the cutting edge while suppressing deformation, and the decrease in the flat area ratio of the slices used as thermally conductive sheets can be suppressed. When |α-β| exceeds 15°, it is presumed that this is because the probability of the slices coming into contact with the sliding plate at their corners increases, but curling of the thermally conductive sheets obtained as slices cannot be suppressed, and the flat area ratio decreases. Figure 4(a) to (d) show examples where |α - β| is between 0° and 15°. For Figure 4(a) to (d), the values ​​of α, β, and |α - β| are as follows: Note that in Figures 4 and 5, the angles are not necessarily the exact numerical values, and may be increased or decreased as appropriate from the indicated numerical values ​​for ease of understanding. (a) α=65°, β=65°, |α-β|=0° (b) α=65°, β=80°, |α-β|=15° (c) α=65°, β=50°, |α-β|=15° (d) α=70°, β=65°, |α-β|=5°

[0048] Note that (e) and (f) in Figure 5 are examples where |α-β| exceeds 15°. For (e) and (f) in Figure 5, the values ​​of α, β, and |α-β| are as follows: (e) α=65°, β=115°, |α-β|=50° (f) α=45°, β=65°, |α-β|=20°

[0049] The angle α is preferably 60° or more, more preferably 62° or more, and even more preferably 65° or more, and is preferably 75° or less, more preferably 72° or less, and even more preferably 70° or less. If the angle α is within the above range, the amount of chips generated by slicing can be sufficiently reduced, and the thermal conductivity of the thermal conductive sheet can be further improved.

[0050] The angle β is preferably 50° or more, more preferably 60° or more, and even more preferably 65° or more, and is preferably 90° or less, more preferably 85° or less, and even more preferably 80° or less. When the angle β is within the above-mentioned range, curling of the heat conductive sheet obtained as slices can be sufficiently suppressed, thereby increasing the flat area ratio. As a result, dropping and peeling during transportation by a pickup arm can be sufficiently suppressed, further improving handleability in mechanized production lines.

[0051] When slicing the laminate, the pressure applied when pressing the side surface of the laminate in the stacking direction against the slide surface is preferably 0.05 MPa or more, more preferably 0.10 MPa or more, particularly preferably 0.20 MPa or more, and preferably 0.50 MPa or less, and more preferably 0.40 MPa or less. If the pressure is 0.05 MPa or more, the thickness precision of the thermally conductive sheet obtained by slicing the laminate can be ensured, while if the pressure is 0.50 MPa or less, crushing of the laminate can be suppressed. In addition, from the viewpoint of slicing the laminate easily, the temperature of the laminate when slicing is preferably set to be −20° C. or higher and 30° C. or lower. [Example]

[0052] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. In the examples and comparative examples, the following evaluation and measurement methods were used:

[0053] <Volume fraction of thermally conductive filler> The volume fraction of the thermally conductive filler in the thermally conductive sheet was calculated using the amount and specific gravity of the thermally conductive filler added and the amount and specific gravity of each resin added. <Flat area ratio> The thermally conductive sheet was placed on a horizontal table, and an image of the thermally conductive sheet was taken from directly above (at a 90-degree imaging angle relative to the surface of the thermally conductive sheet) using a 3D camera (Basler; model number "acA1600-60gm"; 1600 x 1200 pix). For the image, six bar lights (CCS; model number "LDL2-275X") were used to illuminate the thermally conductive sheet. The height of the thermally conductive sheet was measured for the obtained image, and any distorted areas (i.e., areas where the thermally conductive sheet was floating above the table due to curls or wrinkles) were excluded to identify the flat areas. Image processing (smoothing, edge processing, and binarization) was then performed, and the distance of the shortest side of the flat area was defined as the short side L (cm) and the distance of the longest side was defined as the long side W (cm) of the flat area. The area of ​​the main surface of the thermally conductive sheet was determined as S (cm). 2 ) and the flat area ratio was calculated using the following formula. Flat area ratio (%)=(L×W) / S×100 <Identifying chip size, number of chips per specified area> A thermally conductive sheet (150mm x 150mm x 0.1mm) was placed on an inspection stage (200mm x 200mm transparent acrylic plate). A white LED bar light (model number "LDL2-275X" manufactured by CCS; color temperature 7,800K; power consumption 27W) was irradiated from an angle of 40 degrees perpendicular to the surface of the thermally conductive sheet on the inspection stage (50 degrees relative to the surface of the thermally conductive sheet). Images were captured from directly above using an 8K monochrome CMOS line camera (manufactured by Basler; model number "raL8192-12gm"; 8192px x 1px), obtaining an 8-bit monochrome image of the sheet surface. The image was captured by scanning the light and camera parallel to the surface of the thermally conductive sheet. The monochrome image obtained as described above was subjected to image processing (smoothing and edge processing), and then binarized to identify the location of the foreign object, and a foreign object image was obtained by cutting out only the location of the foreign object. From the obtained foreign object image, images of chips were visually picked out, and the major axis length l (mm) and minor axis length s (mm) of the chips were measured from the number of pixels and image resolution, and the chip size was calculated using the following formula. Chip size (mm 2 )=l×s And the size is 0.04mm 2 Over 4.0mm 2 The number of chips N (unit: pieces) that were less than or equal to the size of the chips was counted. The area of ​​the main surface of the thermal conductive sheet was then calculated as S (cm 2 ) and the number of chips per given area was calculated using the following formula. Number of chips per specified area (pieces / 225cm 2 )=N / S×225 The chips were ranked as follows based on the size of the chips whose sizes were identified as described above. A: All observed chips were 0.04 mm in size. 2 Over 0.8mm 2 Within the following range B: All observed chips were 0.8 mm in size. 2 Super 2.0mm 2 Within the following range C: All observed chips were 2.0 mm in size 2 Super 4.0mm 2 Within the following range <Thermal conductivity in the thickness direction> For the thermal conductive sheet, the thermal diffusivity α(m 2 / s), specific heat at constant pressure Cp (J / g K) and specific gravity ρ (g / m 3 ) were measured by the following methods. <<Thermal diffusivity α in the thickness direction>> Measurements were performed using a thermal diffusivity and thermal conductivity measuring device (manufactured by iPhase Corporation, product name "iPhase Mobile 1u") in accordance with the provisions of ISO 22007-3. <<Specific heat at constant pressure Cp>> Using a differential scanning calorimeter (manufactured by Rigaku, product name "DSC8230"), the specific heat was measured at 25°C under conditions of a temperature increase of 10°C / min. <<Specific gravity ρ (density)>> Measurement was carried out using an automatic hydrometer (manufactured by Toyo Seiki Co., Ltd., trade name "DENSIMETER-H"). Then, each measurement value is calculated using the following formula: λ=α×Cp×ρ The thermal conductivity λ (W / m K) of the thermal conductive sheet in the thickness direction at 25°C was calculated by substituting the above formula into the following. Evaluation was then carried out according to the following criteria. A: Thermal conductivity λ is 30 W / m K or more B: Thermal conductivity λ is 20 W / m K or more and less than 30 W / m K C: Thermal conductivity λ is less than 20 W / m K <Average thickness> Using a film thickness meter (manufactured by Mitutoyo, product name "Digimatic Indicator ID-C112XBS"), the thickness was measured at five points in total, the center and four corners of the thermal conductive sheet, and the average value of the measured thicknesses was calculated. <Yield> The mass of the laminate is defined as M0 (g), and the total mass of slices obtained as a heat conductive sheet from one laminate without clogging in the gaps is defined as M1 (g), and the mass is calculated using the following formula: Yield = M1 / M0 x 100 The yield (mass%) was calculated by substituting <Static friction coefficient> The static friction coefficient was measured in accordance with JIS K7312 using a testing machine (manufactured by Shimadzu Corporation, product name "AG-IS20kN"). Specifically, a moving weight adjusted to a total weight of 200 g was placed on a test piece (sliding plate) of approximately 120 x 120 mm fixed to a table, and the weight was pulled horizontally against the test piece at a speed of 100 mm / min to measure the test force (N) when pulling the weight. The obtained test force (N) was calculated using the following formula: μ s =A s / B The coefficient of static friction was calculated by substituting μ s is the coefficient of static friction, A s is the maximum tensile test force (N) at the start, and B is the gravity force (N) due to the weight. <Ease of handling on mechanized lines> <<Focus adjustment>> The sliced ​​thermally conductive sheet was imaged from directly above using an 8K line camera (Basler; model number "rsL8192-12gm"), and the time required for focus adjustment was measured. Evaluation was then based on the following criteria. If the thermally conductive sheet had a main surface with chips attached, the main surface was imaged; if the thermally conductive sheet had no chips attached, an arbitrarily selected surface was imaged. Good: Focus adjustment takes less than 2 seconds Poor: Time required for focus adjustment exceeds 2 seconds or focus adjustment is not possible <<Transportation by pickup arm>> The flat part of the thermal conductive sheet was picked up by a 100mm wide pickup arm with multiple perforations and transported a distance of 50cm. The same test was repeated 10 times, and if the sheet did not fall off or peel off from the pickup arm during transport, it was considered a success, and the success rate (= number of successes / 10 x 100%) was calculated. The waiting time between picking up the thermal conductive sheet and lifting it up was 2 seconds, and the transport speed was 50cm / second. The success rate was evaluated according to the following criteria. A: 100% success rate B: Success rate is 80% or 90% C: Success rate less than 80%

[0054] Example 1 <Manufacturing of laminate> 70 parts of a fluororesin (manufactured by Daikin Industries, Ltd., product name "Dai-el G-101", thermoplastic) that is liquid at room temperature and normal pressure as a resin, 30 parts of a fluororesin (manufactured by 3M Japan Ltd., product name "Dyneon FC2211", thermoplastic) that is solid at room temperature and normal pressure as a resin, and 90 parts of expanded graphite (manufactured by Ito Graphite Industries Co., Ltd., product name "EC300", volume average particle size: 50 μm) as a thermally conductive filler were mixed and stirred at a temperature of 150 ° C. for 20 minutes using a pressure kneader (manufactured by Nippon Spindle). Next, the resulting mixture was placed in a crusher (manufactured by Osaka Chemical Co., Ltd., product name "Wonder Crush Mill D3V-10") and crushed for 10 seconds. The resulting crushed mixture was fed at a feed rate of 250 g / min into a heated roll laminating device (manufactured by Hirano Giken Kogyo Co., Ltd.) in which a 100 μm thick PET film (base film) that had been treated with a release agent and a 75 μm thick PET film (cover film) that had been treated with a release agent different from that of the base film were each placed (contacted) on the surfaces of a pair of rolling rolls, and the mixture was passed through the gap between the rolling rolls to obtain a primary sheet with a thickness of 0.8 mm. The rolling conditions are as follows: Gap width: 650μm Roll temperature: 100℃ Roll line pressure: 0.35 ton / cm Roll speed: 1m / min The obtained primary sheet was cut into a size of 150 mm length x 150 mm width x 0.8 mm thickness, and 188 sheets were stacked in the thickness direction of the primary sheet.Furthermore, by pressing in the stacking direction at a temperature of 23°C and a pressure of 0.2 MPa for 90 minutes, a rectangular stack with a height of approximately 150 mm was obtained. <Formation of thermal conductive sheet> A woodworking slicer (manufactured by Marunaka Iron Works Co., Ltd., product name "Super Finishing Planer Super Mecha S") equipped with a support base with a sliding surface and a blade of the same shape as the blade shown in Figure 3 was used. A sliding plate (rectangular plate in plan view, static friction coefficient: 0.1) was attached perpendicular to the rake surface of the blade as shown in Figure 3 to form a slicing mechanism. The laminate was placed on the slicing mechanism with its side in the stacking direction in contact with the slide surface. The laminate was then pressed against the slide surface at a pressure of 0.3 MPa, sliding the laminate so that its end face in the stacking direction became the main slicing surface, slicing parallel to the stacking direction (i.e., in the direction normal to the main surface of the stacked primary sheets). The resulting slices were thermally conductive sheets measuring 150 mm long x 150 mm wide x 0.10 mm in average thickness. The angle α between the stacking direction of the laminate and the extension direction of the blade was 65°, and the angle β between the stacking direction of the laminate and the extension direction of the slide plate was 65°. Figure 4(a) shows the relative positions of the laminate, blade (cutting edge), and slide plate when viewed from above the slide surface. In Figure 4, D represents a line parallel to the stacking direction of the laminate 10, E represents a line extending in the extension direction of the blade edge, and F represents a line extending in the extension direction of the slide plate. The direction of travel of the laminate 10 is indicated by an arrow. The obtained thermal conductive sheet was then subjected to various evaluations. The results are shown in Table 1. No chips were found on the main surface opposite to the main surface on which the "number of chips per specified area" listed in Table 1 was measured. The same applies to the following examples and comparative examples.

[0055] Example 2 Except for changing the angle β to 80°, a thermally conductive sheet was produced in the same manner as in Example 1. Various evaluations were then carried out in the same manner as in Example 1. The results are shown in Table 1. The positional relationship between the laminate, blade (cutting edge), and slide plate when viewed from above the slide surface is shown in FIG. 4(b).

[0056] Example 3 Except for changing the angle β to 50°, a thermally conductive sheet was produced in the same manner as in Example 1. Various evaluations were then carried out in the same manner as in Example 1. The results are shown in Table 1. The positional relationship between the laminate, blade (cutting edge), and slide plate when viewed from above the slide surface is shown in FIG. 4(c).

[0057] Example 4 Except for changing the angle α to 70°, a thermally conductive sheet was produced in the same manner as in Example 1. Various evaluations were then carried out in the same manner as in Example 1. The results are shown in Table 1. The positional relationship between the laminate, blade (cutting edge), and slide plate when viewed from above the slide surface is shown in FIG. 4(d).

[0058] Example 5 A guide member (length: 3.5 cm, static friction coefficient: 0.1) and an auxiliary guide member (static friction coefficient: 0.1) were further attached to the slicing mechanism used in Example 1 to form a slicing mechanism. The distance between the guide member and the auxiliary guide member was adjusted to 0.5 mm. The attachment of the guide member and auxiliary guide member was performed in accordance with Example 1 of Patent Document 1 (JP 2021-5594 A) and the description in Figure 1 of the document. Except for using the slicing mechanism obtained above, a thermally conductive sheet was produced in the same manner as in Example 1. Various evaluations were then carried out in the same manner as in Example 1. The results are shown in Table 1.

[0059] (Comparative Example 1) A slicing mechanism was created by attaching a guide member and an auxiliary guide member to a woodworking slicer (manufactured by Marunaka Iron Works Co., Ltd., product name "Super Finishing Planer Super Mecha S") equipped with a support base with a sliding surface and a blade with a shape similar to that of the blade shown in Fig. 3, in the same manner as in Example 5. No sliding plate was installed. A thermally conductive sheet was manufactured in the same manner as in Example 1, except that the slicing mechanism obtained above was used and the angle α was changed to 45°. Various evaluations were then carried out in the same manner as in Example 1. The results are shown in Table 1.

[0060] (Comparative Example 2) Except for changing the angle β to 115°, a thermally conductive sheet was produced in the same manner as in Example 1. Various evaluations were then carried out in the same manner as in Example 1. The results are shown in Table 1. The positional relationship between the laminate, blade (cutting edge), and slide plate when viewed from above the slide surface is shown in FIG. 5(e).

[0061] (Comparative Example 3) Except for changing the angle α to 45°, a thermally conductive sheet was produced in the same manner as in Example 1. Various evaluations were then carried out in the same manner as in Example 1. The results are shown in Table 1. The positional relationship between the laminate, blade (cutting edge), and slide plate when viewed from above the slide surface is shown in FIG. 5(f).

[0062] Comparative Example 4 A thermally conductive sheet was produced in the same manner as in Example 1, except that the laminate was slid so that the side surface in the stacking direction became the main slice surface, and the angle α was set to 45° and the angle β was set to 55°. Various evaluations were then carried out in the same manner as in Example 1. The results are shown in Table 1. The positional relationship between the laminate, blade (cutting edge), and slide plate when viewed from above the slide surface is shown in FIG. 5(g).

[0063] (Comparative Example 5) A laminate was produced in the same manner as in Example 1. The obtained laminate was stood on a stand so that the side surface in the stacking direction (surface 15 in FIG. 2) was the bottom, and the entire side surface in the stacking direction (surface 16 in FIG. 2) was pressed down with a metal plate, and a pressure of 0.1 MPa was applied from above (from the side of surface 13 in FIG. 2) to fix the laminate. Note that the other surfaces of the laminate were not fixed. The temperature of the laminate was 25°C. Next, a blade (double-edged, blade angle 2θ: 20°, maximum blade thickness: 3.5 mm, material: carbide, Rockwell hardness: 91, total length: 200 mm) was attached to the press portion of a servo press (manufactured by Electrical Discharge Precision Machining Laboratory), and the laminate was sliced ​​in the stacking direction (in other words, in the direction normal to the main surface of the stacked primary sheets) at a slicing speed of 200 mm / sec to obtain a thermally conductive sheet measuring 150 mm long x 150 mm wide x 0.10 mm average thickness. Various evaluations were then carried out in the same manner as in Example 1. The results are shown in Table 1.

[0064] In Table 1 shown below, "Guide members, etc." means guide members and auxiliary guide members, "End surface" means an end surface of a laminate in the stacking direction, "Side" means the side surface of the laminate in the stacking direction.

[0065] [Table 1]

[0066] It can be seen from Table 1 that the thermally conductive sheets of Examples 1 to 5 have excellent thermal conductivity in the thickness direction and are sufficiently easy to handle on mechanized production lines. [Industrial Applicability]

[0067] According to the present invention, it is possible to provide a thermally conductive sheet that exhibits good thermal conductivity in the thickness direction and is easy to handle on a mechanized line, and a method for manufacturing the thermally conductive sheet. [Explanation of symbols]

[0068] 1. Thermal conductive sheet 2 strips 3 Main Surfaces 4 Chips 10 Laminate 11 Top surface (end surface in stacking direction) 12 Bottom surface (end surface in stacking direction) 13 Stacking direction side 14 Stacking direction side 15 Stacking direction side 16 Stacking direction side 20 Support stand 21 Slide surface 30 blades 31 Rake face 32 Flank 33 Cutting edge 40 gap 50 Slide 60 slices (thermal conductive sheet) D Stacking direction of laminate E Extension direction of cutting edge F Extension direction of sliding plate

Claims

1. A thermally conductive sheet formed by joining a plurality of strips in parallel, the thermally conductive sheet contains a resin and a thermally conductive filler, and has a flat area ratio of 70% or more; At least one of the main surfaces has a planar area of ​​225 cm ２ The size of the contact is 0.04 mm ２ Over 4.0 mm ２ A thermal conductive sheet in which the number of chips is 1.0 or more and 20.0 or less.

2. The thermally conductive sheet according to claim 1 , wherein the volume fraction of the thermally conductive filler is 30% by volume or more and 45% by volume or less.

3. The thermally conductive sheet according to claim 1 or 2, wherein the thermally conductive filler has a volume average particle size of 150 μm or less.

4. A method for producing a thermally conductive sheet, comprising: using a slicing mechanism to slice a laminate of primary sheets containing a resin and a thermally conductive filler along a plane parallel to the lamination direction of the laminate, thereby obtaining a thermally conductive sheet formed by joining a plurality of strips in parallel, The slicing mechanism includes: a support base having a sliding surface; a blade having a flank, a rake face, and a cutting edge formed by an intersection angle between the flank and the rake face, the cutting edge being disposed so as to protrude from the slide surface; a gap formed in the support base along the cutting surface through which a slice cut from the stack by contact with the cutting edge can pass; and a slide plate disposed substantially perpendicular to the rake face and capable of receiving the sliced ​​piece that has passed through the gap; The slicing is performed by pressing the side surface of the stack in the stacking direction against the slide surface, sliding the stack so that the end surface of the stack in the stacking direction becomes a main slicing surface and bringing it into contact with the blade, and sliding the sliced ​​pieces cut out from the stack along the slide plate to collect them, and A method for manufacturing a thermal conduction sheet, wherein, when the laminate and the slicing mechanism are viewed in a plane from the slide surface side during slicing, the absolute value of the difference between the angle α from the stacking direction of the laminate to the extension direction of the cutting edge of the blade and the angle β from the stacking direction of the laminate to the extension direction of the slide plate is 0° or more and 15° or less.

5. The method for manufacturing a thermal conductive sheet according to claim 4 , wherein the angle α is equal to or greater than 60° and equal to or less than 75°.

6. The method for manufacturing a thermally conductive sheet according to claim 4 or 5, wherein the sliding plate has a surface that comes into contact with the sliced ​​piece cut out from the laminate, the surface having a static friction coefficient of 0.4 or less.

Images