HEAT-CONDUCTIVE SHEET AND METHOD FOR MANUFACTURING SAME
A thermally conductive sheet 10 contains a matrix resin 11 , filler molded pieces 12 containing a first thermally conductive filler 15 with shape anisotropy, and a second thermally conductive filler 13 . The filler molded pieces 12 contain a binder resin 14 and the first thermally conductive filler 15 . The first thermally conductive filler 15 is oriented in the thickness direction of each of the filler molded pieces 12 . The first thermally conductive filler 15 is also oriented in the thickness direction of the thermally conductive sheet 10 when present in the thermally conductive sheet 10 . This configuration provides a thermally conductive sheet with a high thermal conductivity and a large size, and a method for producing the thermally conductive sheet.
1 . A thermally conductive sheet comprising:
a matrix resin;
filler molded pieces containing a first thermally conductive filler with shape anisotropy; and
a second thermally conductive filler,
wherein the matrix resin, the filler molded pieces, and the second thermally conductive filler are mixed together,
the filler molded pieces contain a binder resin and the first thermally conductive filler,
the first thermally conductive filler is oriented in a thickness direction of each of the filler molded pieces, and
the first thermally conductive filler is also oriented in a thickness direction of the thermally conductive sheet when present in the thermally conductive sheet.
2 . The thermally conductive sheet according to claim 1 , wherein the first thermally conductive filler with shape anisotropy is a filler having at least one shape selected from a plate and a needle.
3 . The thermally conductive sheet according to claim 1 , wherein the first thermally conductive filler with shape anisotropy is composed of at least one selected from boron nitride and alumina.
4 . The thermally conductive sheet according to claim 1 , wherein the matrix resin and the binder resin are the same type or different types of thermosetting resins.
5 . The thermally conductive sheet according to claim 1 , wherein both the matrix resin and the binder resin are silicone polymers.
6 . The thermally conductive sheet according to claim 1 , wherein the filler molded pieces further contain at least one selected from a spherical thermally conductive filler and an irregularly-shaped thermally conductive filler.
7 . The thermally conductive sheet according to claim 1 , wherein the second thermally conductive filler contains at least one selected from a spherical thermally conductive filler and an irregularly-shaped thermally conductive filler.
8 . The thermally conductive sheet according to claim 1 , wherein a thermal conductivity of the thermally conductive sheet is 1.5 W/m·K or more.
9 . A method for producing a thermally conductive sheet,
the thermally conducive sheet comprising:
a matrix resin;
filler molded pieces containing a first thermally conductive filler with shape anisotropy; and
a second thermally conductive filler,
wherein the matrix resin, the filler molded pieces, and the second thermally conductive filler are mixed together,
the filler molded pieces contain a binder resin and the first thermally conductive filler,
the first thermally conductive filler is oriented in a thickness direction of each of the filler molded pieces, and
the first thermally conductive filler is also oriented in a thickness direction of the thermally conductive sheet when present in the thermally conductive sheet,
the method comprising:
forming a sheet or block by pressure processing of a mixture of a binder resin and a first thermally conductive filler with shape anisotropy so that the first thermally conductive filler is oriented in a main surface direction of the sheet or block;
curing the binder resin and then cutting the sheet or block in a thickness direction to obtain filler molded pieces, in each of which the first thermally conductive filler is oriented in a thickness direction of the filler molded piece; and
mixing the filler molded pieces, a matrix resin, and a second thermally conductive filler, molding the mixture into a sheet shape, and then curing the matrix resin.
10 . The method according to claim 9 , wherein the pressure processing is at least one selected from pressing and rolling.
11 . The thermally conductive sheet according to claim 1 , wherein the second thermally conductive filler includes at least two types of inorganic particles with different average particle sizes.
12 . The method according to claim 9 , wherein the first thermally conductive filler with shape anisotropy is a filler having at least one shape selected from a plate and a needle.
13 . The method according to claim 9 , wherein the first thermally conductive filler with shape anisotropy is composed of at least one selected from boron nitride and alumina.
14 . The method according to claim 9 , wherein the matrix resin and the binder resin are the same type or different types of thermosetting resins.
15 . The method according to claim 9 , wherein both the matrix resin and the binder resin are silicone polymers.
16 . The method according to claim 9 , wherein the filler molded pieces further contain at least one selected from a spherical thermally conductive filler and an irregularly-shaped thermally conductive filler.
17 . The method according to claim 9 , wherein the second thermally conductive filler contains at least one selected from a spherical thermally conductive filler and an irregularly-shaped thermally conductive filler.
18 . The method according to claim 9 , wherein a thermal conductivity of the thermally conductive sheet is 1.5 W/m·K or more.