KR102472849B1 - Manufacturing Method of Thermally Conductive Sheet using Liquid Material Dispenser - Google Patents

Abstract

The present invention relates to a method for manufacturing a thermally conductive sheet, and more specifically, to a method for manufacturing a thermally conductive sheet using a liquid raw material discharging device comprising: an outlet which is extended along a first central axis as a part of discharging a liquid thermally conductive composition to the outside; and a mold which accommodates a liquid discharged object discharged from the outlet. The method for manufacturing a thermally conductive sheet comprises: a liquid raw material discharging step of reciprocating a relative position between the outlet and the mold several times along a second central axis, and accommodating the liquid discharged object discharged from the outlet in the mold in a state of extending by a predetermined length along the second central axis; a molded object stabilizing step of exposing the liquid discharged object accommodated in the mold at a predetermined temperature for a predetermined time through the liquid raw material discharging step; a molded object curing step of obtaining a cured molded object by curing the stabilized discharged object through the molded object stabilizing step; and a molded object cutting step of obtaining a sheet having a predetermined thickness by cutting the cured molded object cured through the molded object curing step to a cutting direction crossing the second central axis. The present invention easily manufactures a large-sized thermally conductive sheet without a separate pressing step or an adhesive step, and facilitates rapid mass production.

Description

Manufacturing method of thermally conductive sheet using liquid material dispenser {Manufacturing Method of Thermally Conductive Sheet using Liquid Material Dispenser}

The present invention relates to a method for manufacturing a thermally conductive sheet, and in particular, unlike conventional manufacturing methods, it relates to a method for manufacturing a thermally conductive sheet capable of mass-producing large-sized thermally conductive sheets without a separate pressing process or bonding process. .

In general, electronic products such as computers, portable personal terminals, and communication devices do not spread excessive heat generated inside the system to the outside, so there are serious concerns about afterimage problems and system stability. Since this heat shortens the lifespan of a product, causes failure or malfunction, and even provides a cause of explosion or fire in severe cases, it is becoming important to efficiently dissipate heat generated from electronic components.

Conventionally, radiating fins, radiating sheets, and heat sinks have been used as means for efficiently controlling generated heat. There was a problem that the heat dissipation fan had to be installed together because it was very low.

In particular, due to the simultaneous installation of heat dissipation fans, problems of noise and vibration generated from the heat dissipation fan occur, as well as problems that cannot be applied to products requiring light weight and slimness, which is recently called heat dissipation. Sheets are widely used.

A conventional heat dissipation sheet is a type of thermally conductive sheet, and a resin composition in which an inorganic filler having thermal conductivity such as copper, alumina, ferrite, aluminum nitride, or aluminum hydroxide is dispersed and contained is widely used.

However, when the content of the inorganic filler is low, the thermal conductivity of such a heat radiation sheet is very low, and when the content of the inorganic filler is high, the content of other components is reduced, resulting in poor bonding strength between powders, as well as flexibility and moldability of the sheet. In addition to this problem of deterioration, the conventional thermal conductive sheet containing inorganic fillers has a very low thermal conductivity of 1.5 to 5 W/m·K even when the content of the inorganic filler is increased, so that heat cannot be dissipated efficiently. There was a problem.

Recently, in order to solve the problem of the heat radiation sheet containing the inorganic filler as described above, a heat radiation sheet having increased thermal conductivity by further containing carbon fibers having anisotropy has been manufactured, and Korean Patent Publication (Publication No. 10- 2013-0117752 published on October 28, 2013) discloses a technique for manufacturing a heat radiation sheet by forming a sheet base material by extrusion molding and slicing the cured sheet base material to a predetermined thickness.

However, when manufacturing a heat radiation sheet by slicing the sheet base material formed by extrusion molding in this way, the diameter of the sheet base material is limited due to the limitations of extrusion molding itself, so a large size heat radiation sheet cannot be manufactured and mass production cannot be achieved. There were several problems such as no.

The present invention has been made to solve the above problems, and its object is to provide an improved method for manufacturing a thermally conductive sheet that can mass-produce large-sized thermally conductive sheets without a separate pressing process or bonding process.

In order to achieve the above object, a method for manufacturing a thermally conductive sheet according to the present invention extends along a first central axis as a portion for discharging a liquid thermally conductive composition containing a polymer, an anisotropic thermally conductive filler, and a filler to the outside. A method of manufacturing a thermal conductive sheet using a liquid raw material ejector including a discharge port and a mold for molding that accommodates a liquid ejected from the ejection hole, wherein the relative position between the ejection hole and the mold for molding is determined with respect to a second central axis. a liquid raw material discharge step of accommodating the liquid discharge material discharged from the discharge port into the molding mold in a state in which the liquid discharge material is extended by a predetermined length along the second central axis by reciprocating several times along the second central axis; a molded product stabilization step of exposing the liquid discharged material accommodated in the molding mold through the liquid raw material discharging process to a predetermined temperature for a predetermined time; a molding curing step of obtaining a cured molding by curing the discharge material stabilized through the molding stabilization step at a predetermined temperature for a predetermined time; and a molding cutting step of obtaining a sheet having a predetermined thickness by cutting the cured molding cured through the molding curing step in a cutting direction crossing the second central axis.

Here, in the liquid raw material discharging step, the discharge port reciprocates multiple times along the second central axis with respect to the molding mold along a third central axis intersecting the second central axis with respect to the molding mold. It is preferable that the liquid discharged material discharged from the discharge port covers at least a part of the entire area of the molding die by relative movement.

Here, in the liquid raw material discharging step, the discharge port reciprocates multiple times along the second central axis with respect to the molding mold along a third central axis intersecting the second central axis with respect to the molding mold. By relative movement, it is preferable to relative move in a zigzag form.

Here, in the liquid raw material discharging step, it is preferable that the liquid discharged material discharged from the discharge port is discharged in a state in which a plurality of layers are stacked on the molding die.

Here, it is preferable that the shaping mold has an internal space of a rectangular parallelepiped shape extending along the second central axis, and an upper end portion is open.

Here, the liquid raw material ejector may include a cylinder accommodating the liquid thermally conductive composition therein; and a piston capable of reciprocating movement inside the cylinder, and the discharge port is preferably provided at one end of the cylinder.

Here, the discharge port preferably includes a pipe-shaped member having an inner diameter of 1 to 5 mm.

Here, the liquid discharge material discharged from the discharge port preferably has a viscosity of 100,000 to 1,000,000 cPs.

Here, it is preferable to further include a sheet surface processing step of smoothing the surface of the sheet prepared to have a predetermined thickness in the molding cutting process to a predetermined roughness or less.

Here, in the sheet surface processing step, it is preferable to smooth the surface of the sheet by pressing the sheet along the thickness direction of the sheet using a press molding machine.

Here, it is preferable that the said polymer contains a silicone resin.

Here, the filler preferably includes at least one of aluminum oxide, aluminum nitride, zinc oxide, silicon powder, and metal powder.

Here, the filler preferably includes spherical aluminum oxide particles having an average particle diameter of 0.1 μm to 45 μm.

Here, it is preferable that the content of the filler in the thermally conductive composition is 20% by volume to 40% by volume.

Here, the content of the anisotropic thermally conductive filler in the thermally conductive composition is preferably 20% by volume to 50% by volume.

Here, the anisotropic thermally conductive filler preferably includes at least one selected from the group consisting of boron nitride (BN) powder, graphite, carbon fiber, and carbon nanotube (CNT).

According to the present invention, a discharge port extending along a first central axis as a portion for discharging a liquid thermal conductive composition containing a polymer, an anisotropic thermal conductive filler, and a filler to the outside, and a liquid discharge material discharged from the discharge port A method for manufacturing a thermally conductive sheet using a liquid raw material discharger including a mold for accommodating the liquid material discharged from the discharge port by reciprocating a relative position between the discharge port and the mold for forming multiple times along a second central axis. a liquid raw material discharge step of accommodating the discharged product in the molding mold in a state in which the discharged product is extended by a predetermined length along the second central axis; a molded product stabilization step of exposing the liquid discharged material accommodated in the molding mold through the liquid raw material discharging process to a predetermined temperature for a predetermined time; a molding curing step of obtaining a cured molding by curing the discharge material stabilized through the molding stabilization step at a predetermined temperature for a predetermined time; A molding cutting step of obtaining a sheet having a predetermined thickness by cutting the cured molding cured through the molding curing step in a cutting direction intersecting the second central axis; Unlike the conventional manufacturing method in which the diameter of the base material is limited, it is possible to easily manufacture a large-sized thermal conductive sheet without a separate pressing process or bonding process by increasing the size of the molding mold, and rapid mass production is easy. It works.

1 is a view showing a liquid raw material discharger used to manufacture a thermal conductive sheet according to an embodiment of the present invention.
FIG. 2 is a perspective view for explaining a process of discharging a thermally conductive composition into the molding mold shown in FIG. 1;
FIG. 3 is a cross-sectional view showing a state in which a thermally conductive composition is ejected and stacked in several layers inside the molding mold shown in FIG. 2 .
FIG. 4 is a cross-sectional view showing a state after the laminated discharge material shown in FIG. 3 is stabilized for a certain period of time.
FIG. 5 is a view for explaining an example of a molding cutting process shown in FIG. 9 .
FIG. 6 is an enlarged view showing a cross section of a thermal conductive sheet completed by the molding cutting process shown in FIG. 5 .
FIG. 7 is a view for explaining an example of a sheet surface processing process shown in FIG. 9 .
8 is a view for explaining a change in an orientation angle of an anisotropic thermally conductive filler that occurs when a main process of a method of manufacturing a thermally conductive sheet according to an embodiment of the present invention is performed.
9 is a flowchart for explaining a method of manufacturing a thermally conductive sheet according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a liquid raw material ejector used to manufacture a thermally conductive sheet according to an embodiment of the present invention, and FIG. 2 is a diagram illustrating a process of discharging a thermally conductive composition into the molding mold shown in FIG. 1 It is a perspective view for 3 is a cross-sectional view showing a state in which a thermally conductive composition is ejected and stacked in several layers inside the molding mold shown in FIG. 2, and FIG. 9 is for explaining a method of manufacturing a thermally conductive sheet according to an embodiment of the present invention. It is a flow chart.

A method for manufacturing a thermally conductive sheet according to a preferred embodiment of the present invention is a method for manufacturing a thermally conductive sheet 100 used to dissipate excessive heat generated from electronic products such as portable personal terminals and communication devices to the outside, As shown in FIG. 9 , a liquid raw material discharging process (S40), a molding stabilization process (S50), a molding curing process (S60), and a molding cutting process (S70) are included.

First, before explaining the processes (S40 to S70) of the manufacturing method of the thermal conductive sheet, the liquid raw material discharger 200 shown in FIGS. 1 to 2 and the base material of the thermal conductive sheet 100 The thermally conductive composition (M) will be described first.

The liquid raw material discharger 200 is a dispenser capable of discharging the liquid thermal conductive composition M at a uniform pressure and flow rate, and as shown in FIG. 1, the cylinder 210 and the piston 220 ) and a discharge port 230 and a molding mold 240.

The cylinder 210 is a container-shaped member capable of accommodating the liquid thermal conductive composition M therein, and as shown in FIG. 1, in the present embodiment, it extends vertically along the first central axis C1. It is provided in a cylindrical shape.

The piston 220 is a piston capable of reciprocating movement within the cylinder 210 along the first central axis C1, and may pressurize the thermally conductive composition M accommodated in the cylinder 210. arranged so that

In this embodiment, the piston 220 may pressurize the liquid thermally conductive composition M at a pressure of 1 to 10 kgf.

The discharge port 230 is a portion for discharging the liquid thermal conductive composition M accommodated inside the cylinder 210 to the outside, and in the present embodiment, has a predetermined length along the first central axis C1 ( L) is extended.

The length (L) of the discharge port 230 is preferably determined appropriately in consideration of the viscosity and composition ratio of the thermally conductive composition (M).

As the length L of the outlet 230 increases, the orientation of the anisotropic thermal conductive filler 1 improves, but the discharge pressure rises, and if the length L of the outlet 230 is too short, the anisotropic thermal conductivity There is a disadvantage that the orientation of the conductive filler 1 is lowered.

In this embodiment, the outlet 230 includes a pipe-like member having a circular cross-section with a length L of 40 to 60 mm and an inner diameter d of 1 to 5 mm.

The upper end of the discharge port 230 is coupled to the lower end of the cylinder 210 and communicates with the inside of the cylinder 210, and the liquid thermal conductive composition M flows through the lower end of the discharge port 230. is discharged

The molding mold 240 is a container-type mold capable of accommodating the liquid discharged material M discharged from the discharge port 230, and has a bottom portion 241 and a bottom portion 241 as shown in FIGS. 1 and 2 It includes a side wall portion 242 and an inner space 243 .

In this embodiment, the molding mold 240, as shown in FIG. 2, has a rectangular parallelepiped-shaped inner space having a second central axis C2 perpendicularly intersecting the first central axis C1 in the longitudinal direction. (243) is available.

In this embodiment, the inner space 243 has a third central axis C3 perpendicularly crossing the first central axis C1 and the second central axis C2 in the width direction, and the first It has a central axis C1 in the thickness direction.

As a result, the size and shape of the inner space 243 determines the size and shape of the laminated molding S shown in FIG. 5 .

As shown in FIG. 2, since the upper end of the mold 240 is open, as shown in FIG. 1, the liquid thermal conductive composition M discharged from the liquid raw material ejector 200 falls It may be put into the inner space 243.

As shown in FIG. 1 , the bottom portion 241 is a rectangular flat portion elongated along the second central axis C2.

The side wall portion 242 is a rectangular portion constituting the side wall of the molding mold 240 , and a lower end thereof is coupled to an edge of the bottom portion 241 .

Eventually, the inner space 243 is formed by the bottom part 241 and the side wall part 242 .

1, the liquid raw material ejector 200 is simply expressed in the form of a general syringe, but this is only a conceptual expression and can actually be implemented as a complex automatic device including an electrical device or a hydraulic and pneumatic device. .

Meanwhile, although not separately shown, the liquid raw material ejector 200, as shown in FIG. It includes an automatic transfer device (not shown) capable of relative movement with respect to the mold 240 .

The automatic feed device (not shown) may include one of various components such as a ball screw and a linear motor.

The liquid raw material discharger 200 is a dispenser that discharges the liquid thermal conductive composition M in a fixed amount, and since the discharged material M discharged through the discharge port 230 is in a liquid state, the discharged material ( M) is clearly distinguished from extruders used to make objects with fixed cross-sectional contours required by designers in that the cross-sectional contour cannot maintain a circular shape.

As shown in FIG. 8, the thermally conductive composition (M) contains a polymer (3), an anisotropic thermally conductive filler (1), and a filler (2).

The polymer 3 is not particularly limited and can be appropriately selected depending on the performance required of the thermal conductive sheet 100. Examples include thermoplastic polymers and thermosetting polymers.

As said thermoplastic polymer, a thermoplastic resin, a thermoplastic elastomer, these polymer alloys, etc. are mentioned. The thermoplastic resin is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include ethylene-α-olefin copolymers such as polyethylene, polypropylene, and ethylene-propylene copolymers; fluorine-based resins such as polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyacetal, polyvinylidene fluoride, and polytetrafluoroethylene; Polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyacrylonitrile, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer (ABS) resin, polyphenylene ether, modified poly Phenylene ether, aliphatic polyamides, aromatic polyamides, polyamideimide, polymethacrylic acid or its esters, polyacrylic acid or its esters, polycarbonate, polyphenylene sulfide, polysulfone, polyethersulfone, polyethernitrile , polyether ketones, polyketones, liquid crystal polymers, silicone resins, ionomers, and the like. These may be used individually by 1 type, and may use 2 or more types together.

Examples of the thermoplastic elastomer include styrene-based thermoplastic elastomers such as styrene-butadiene copolymers or hydrogenated polymers thereof, styrene-isoprene block copolymers or hydrogenated polymers thereof, olefin-based thermoplastic elastomers, vinyl chloride-based thermoplastic elastomers, and polyester-based thermoplastic elastomers. Thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and the like are exemplified. These may be used individually by 1 type, and may use 2 or more types together.

Examples of the thermosetting polymer include crosslinked rubber, epoxy resin, polyimide resin, bismaleimide resin, benzocyclobutene resin, phenol resin, unsaturated polyester, diallylphthalate resin, silicone resin, polyurethane, and polyimide. Silicone, thermosetting type polyphenylene ether, thermosetting type modified polyphenylene ether, etc. are mentioned. These may be used individually by 1 type, and may use 2 or more types together.

Examples of the crosslinked rubber 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, fluororubber, Urethane rubber, acrylic rubber, polyisobutylene rubber, silicone rubber, etc. are mentioned. These may be used individually by 1 type, and may use 2 or more types together.

Among these, silicone resins are particularly preferred in terms of excellent molding processability and weather resistance, as well as adhesion and followability to electronic parts.

The silicone resin is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include addition reaction type liquid silicone rubber and heat vulcanization type mable type silicone rubber using peroxide as vulcanization. Among these, addition reaction type liquid silicone rubber is particularly preferred as a heat dissipating member for electronic devices, since adhesion between the heat generating surface and the heat sink surface of electronic parts is required.

The shape of the anisotropic thermal conductive filler 1 is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include a scale shape, a plate shape, a column shape, a prismatic shape, an ellipse shape, and a flat shape. . Among these, a flat shape is particularly preferable in terms of anisotropic thermal conductivity.

Examples of the anisotropic filler include boron nitride (BN) powder, graphite, carbon fiber, and carbon nanotube (CNT). Among these, carbon fibers are particularly preferred in terms of anisotropic thermal conductivity.

As the carbon fiber, for example, those synthesized by pitch-based, PAN-based, arc discharge method, laser evaporation method, CVD method (chemical vapor deposition method), CCVD method (catalytic chemical vapor deposition method), etc. can be used. Among these, pitch-based carbon fibers are particularly preferred in terms of thermal conductivity.

The carbon fiber may be used by subjecting part or all of it to surface treatment, if necessary. As the surface treatment, for example, oxidation treatment, nitriding treatment, nitration, sulfonation, or a functional group introduced into the surface by these treatments, or metal, metal compound, organic compound, etc. are attached to the surface of the carbon fiber. Or the processing etc. which are combined are mentioned. As said functional group, a hydroxyl group, a carboxyl group, a carbonyl group, a nitro group, an amino group etc. are mentioned, for example.

The average major axis length (average fiber length) of the carbon fibers is preferably 100 μm or more, and more preferably 120 μm to 6 mm. When the average major axis length is less than 100 μm, there are cases where sufficient anisotropic thermal conductivity cannot be obtained, and thermal resistance may increase. The average minor axis length of the carbon fibers is preferably 6 μm to 15 μm, and more preferably 8 μm to 13 μm.

The aspect ratio (average major axis length/average minor axis length) of the carbon fibers is preferably 8 or more, and more preferably 12 to 30. When the aspect ratio is less than 8, the carbon fiber has a short fiber length (major axis length), so the thermal conductivity may decrease.

It is preferable that the content of the anisotropic thermally conductive filler in the thermally conductive composition is 20% by volume to 50% by volume. Here, if the content is less than 20% by volume, sufficient thermal conductivity may not be imparted to the molded article, and if it exceeds 50% by volume, moldability and orientation may be affected.

The filler 2 is not particularly limited in its shape, material, average particle diameter, etc., and can be appropriately selected according to the purpose. The shape is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include a spherical shape, an elliptical spherical shape, a block shape, a granular shape, a flat shape, and a needle shape. Among these, a spherical shape and an elliptical shape are preferable from the viewpoint of filling properties, and a spherical shape is particularly preferable.

Examples of the material of the filler 2 include aluminum nitride, silica, alumina, boron nitride, titania, glass, zinc oxide, silicon carbide, silicon powder, silicon oxide, aluminum oxide, and metal powder. These may be used individually by 1 type, and may use 2 or more types together. Among these, alumina, boron nitride, aluminum nitride, zinc oxide, and silica are preferable, and alumina and aluminum nitride are particularly preferable in terms of thermal conductivity.

In addition, the filler 2 may be subjected to surface treatment. Treatment with a coupling agent as the surface treatment improves dispersibility and improves flexibility of the thermally conductive sheet 100 . Moreover, the surface roughness obtained by cutting can be made smaller.

In this embodiment, the filler 2 includes spherical aluminum oxide particles having an average particle diameter of 0.1 μm to 45 μm. If the average particle diameter is less than 0.1 μm, it may cause curing failure, and if it exceeds 45 μm, the orientation of the carbon fibers may be inhibited and the thermal conductivity of the cured molded product (S1) may be reduced.

In this embodiment, the content of the filler 2 in the thermally conductive composition is 20% by volume to 40% by volume.

The thermally conductive composition may further contain solvents, thixotropic imparting agents, dispersing agents, curing agents, curing accelerators, retarders, fine tackifiers, plasticizers, flame retardants, antioxidants, stabilizers, colorants, etc., as necessary. Other ingredients can be combined.

Here, Thixotropic is a property that becomes a liquid-like sol (SOL) state during flow and maintains a gel (GEL) state in which the viscosity rises in a stable state. , It is a property that does not flow down in the state of being applied to an adherend, and is a property that can impart a kind of time-dependent viscosity.

The thermally conductive composition can be prepared by mixing the polymer 3, the anisotropic thermally conductive filler 1 and the filler 2, and, if necessary, the other components using a mixer or the like.

Hereinafter, a detailed description of the manufacturing method of the thermally conductive sheet will be given.

First, raw materials such as the anisotropic thermally conductive filler (1), the filler (2), and the polymer (3) in predetermined amounts are put into a planetary mixer, respectively, and then mixed relatively slowly at a speed of 5 to 50 rpm. let it This is a kind of pre-mixing process.

Here, the planetary mixer is a mixer capable of mixing the raw materials while the mixing blades rotate and rotate simultaneously, and the liquid thermally conductive composition (M) having various viscosities from low viscosity to high viscosity is stirred It is a mixer that is advantageous for kneading or kneading. Since this mixer is widely used in the art, a detailed description thereof will be omitted. (1st mixing process; S10)

In this way, the raw materials pre-mixed by the primary mixing step (S10) are put into a mixing defoamer and then mixed at a relatively high speed of 50 to 500 rpm, while removing air bubbles present inside the raw materials together. do.

Here, the mixing defoamer is a device capable of performing both mixing and defoaming by mixing blades at the same time, and is equipped with a vacuum pump for removing air bubbles present in the raw material to be mixed.

Therefore, the removal of air bubbles present in the thermally conductive composition (M) and the mixing of raw materials are simultaneously performed by the mixing deaerator. (Second mixing process; S20)

The thermally conductive composition M, which has been sufficiently degassed and mixed through the secondary mixing process (S20), is introduced into the raw material storage tank (not shown) of the liquid raw material discharger 200. Here, the raw material storage tank (not shown) communicates with the cylinder 210 .

The operation of injecting the thermally conductive composition M into the raw material storage tank (not shown) may be manually performed by a worker or may be automatically performed by an injection pump or the like.

In this embodiment, in a state where the thermally conductive composition (M) is put into the raw material storage tank (not shown), an additional degassing operation is performed using a vacuum pump to completely remove internal bubbles of the thermally conductive composition (M). (raw material tank injection process; S30)

In this way, after the preparation for discharging the thermally conductive composition M is completed through the raw material tank injection step (S30), the molding mold 240 is placed under the discharge port 230, and then the liquid raw material discharger ( 200) to operate.

When the liquid raw material discharger 200 is operated, the liquid thermal conductive composition M is gradually discharged from the discharge port 230 and injected into the inner space 243 of the molding mold 240 .

In this embodiment, the liquid discharged material M discharged from the discharge port 230 has a viscosity of 100,000 to 1,000,000 cPs.

When the viscosity of the liquid discharged material M discharged from the discharge port 230 is too low, such as less than 100,000 cPs, and the liquidity is excessive, the discharged product M discharged from the discharge port 230 is the mold 240 for molding. As soon as it contacts the bottom portion 241 of ), the cylindrical cross-section as shown in FIG. 3 is immediately lost and deformed flat, causing a problem of being in close contact with the bottom portion 241, and accordingly, the anisotropic thermally conductive filler (1 ) is also reduced.

Conversely, when the viscosity of the liquid discharged material M discharged from the outlet 230 exceeds 1,000,000 cPs and its fluidity is reduced, the liquid discharged product M discharged from the outlet 230 Even after being placed on the bottom part 241 of the mold 240 as shown in FIG. 3, the cylindrical cross-section is maintained for an excessively long time or permanently, so that the laminated ejection material ( A problem arises in that the air bubbles (G) existing inside the MS) are not removed.

Meanwhile, since the outlet 230 vertically extends vertically by a predetermined length L along the first central axis C1 and has a relatively small inner diameter d, the thermally conductive composition M While passing through the outlet 230, the anisotropic thermal conductive filler 1, which was randomly oriented inside the thermally conductive composition M, due to gravity and a guide effect by the inner circumferential surface of the outlet 230, It is aligned to some extent to have an angle within a predetermined angle with the first central axis C1, which is the longitudinal direction of 230.

And, from the moment the discharge material M discharged from the discharge port 230 contacts the bottom portion 241 of the molding mold 240, as shown in FIG. 2, the automatic transfer device (not shown) moves the discharge port 230 in a three-dimensional position with respect to the forming mold 240 in the front-back direction (A), left-right direction (B), and up-and-down direction (C). A detailed explanation of this process is as follows.

First, after locating the outlet 230 at the upper left corner of the molding mold 240 shown in FIG. ) is moved to the upper right corner, the first line of discharge material M1 having a straight noodle strand shape is disposed on the bottom portion 241.

Next, when the discharge port 230 is slightly moved along the left-right direction (B) and then moved to the left side of the molding mold 240 along the front-back direction (A), the second noodle having a shape of straight noodle strands. One line of discharge material M1 is placed on the bottom part 241 . At this time, as shown in FIG. 3, the two lines of discharged material M1 are in close contact with each other without gaps.

Of course, as shown in FIG. 2, near both ends of the molding mold 240 to which the two lines of ejection objects M1 are connected, a plurality of 'U'-shaped curved ejection objects M1 are formed. Since this part has poor orientation of the anisotropic thermally conductive filler 1, it is a part to be discarded after cutting in a molding cutting process (S70) to be described later.

In this way, while the discharge port 230 reciprocates several times along the second central axis C2 with respect to the molding mold 240, intermittently with respect to the molding mold 240, the third 2 When the relative movement in the form of a "zigzag" relative movement along the third central axis C3 intersecting the central axis C2, the liquid discharged from the discharge port 230 as shown in FIG. 2 (M1) is formed of one layer of ejected material (M1) covering the entire area of the bottom portion 241 of the mold 240 for molding.

When the discharge port 230 is moved in the same way after forming one layer of the discharge material M1 in this way, as shown in FIG. 3, the liquid discharge material M is formed, ), stacked ejection materials (MS) in the form of rod lumps are formed in a state of being stacked in a plurality of layers (M1, M2, M3, M4, M5).

However, since the stacked discharge material MS still has a liquid property to some extent, as shown in FIG. many exist. (Liquid raw material discharging process; S40)

Subsequently, the laminated discharge material MS obtained in a state accommodated in the molding mold 240 through the liquid raw material discharge process (S40) is left at room temperature for approximately 30 minutes to 1 hour.

In FIG. 3, the cross section of the stacked discharge material MS is expressed as a bundle in which a plurality of circular cross sections are gathered, but in reality, the first layer M1 before the second layer M2 is formed, as shown in FIG. It does not have a shape, but has a sheet shape from which air bubbles (G) are removed, as shown in FIG. 4 . However, the bubble (G) removal rate may vary depending on conditions such as the viscosity and discharge rate of the thermally conductive composition (M).

In this way, when the stacked discharged material MS is left for a certain period of time in a state accommodated in the molding mold 240, the stacked discharged material MS still has a liquid state and the entire stacked discharged material MS Since gravity continues to act on the layer, the air bubbles (G) inside from the ejection material (M1) located at the bottom of the layer rise upward due to the density difference and are sequentially discharged into the atmosphere to be removed, and eventually the stacked ejection material ( By removing all of the air bubbles (G) inside the MS), the laminated discharge material (MS) is stabilized in a bubbled state like the laminated molding (S) shown in FIG. 4 .

On the other hand, due to the bubbles (G) that escaped during the process of removing the bubbles (G), the volume of the laminated molding (S) has a slightly smaller value than the volume of the laminated discharge material (MS), and this effect is similar to that of a press This causes an effect similar to processing, and as shown in FIG. 8, the orientation of the anisotropic thermally conductive filler 1 is further improved. (Molded product stabilization process; S50)

After obtaining the laminated molding (S) from which air bubbles (G) in the interior of the laminated ejection product (MS) are completely removed through the molding stabilization process (S50), the laminated molding (S) is stored for a predetermined time. When cured at a temperature, a rectangular parallelepiped bar-shaped cured molding S1 as shown in FIG. 5 is obtained without a separate pressing process or bonding process for the plurality of layers M1, M2, M3, M4, and M5.

The curing method of the laminated molding S is not particularly limited and can be appropriately selected according to the purpose. When a thermosetting resin such as a silicone resin is used as the polymer, curing by heating is preferable.

As an apparatus used for the said heating, a dry oven, a far-infrared furnace, a hot stove, etc. are mentioned. The heating temperature is not particularly limited and can be appropriately selected according to the purpose.

The flexibility of the cured silicone molded product (S1) in which the silicone resin is cured is not particularly limited, and can be appropriately selected according to the purpose, and can be adjusted by, for example, the crosslinking density of silicone and the filling amount of the thermally conductive filler.

In this embodiment, the laminated molding (S) was put into a dry oven and cured at a temperature of 70 to 150° C. for about 1 to 10 hours. (Moulded product hardening process; S60)

Subsequently, the cured molding (S1) cured through the molding curing process (S60) is cut using the ultrasonic cutter 400 as shown in FIG. 5, and as shown in FIG. 6, the predetermined thickness (t ) The thermal conductive sheet 100 having a is obtained.

At this time, the blade of the ultrasonic cutter 400, as shown in Figure 5, by slowly descending while vibrating along the longitudinal direction (C2) and substantially perpendicular to the vibration direction (V) of the curing molding (S1), The cured molding (S1) is cut. (Moulded product hardening process; S60)

After the thermal conductive sheet 100 having the thickness t is obtained as described above, as shown in FIG. When heated and pressed, both surfaces of the thermally conductive sheet 100 are processed smoothly to a predetermined roughness or less.

In this embodiment, the press molding machine 300, as shown in Figure 7, the rectangular pressing member 310, which can descend along the pressing direction (P) or rise in the opposite direction, and the pressing member 310 ) and a mold member 320 having a rectangular parallelepiped internal space having a predetermined shape to correspond to.

When the pressing process is performed through the press molding machine 300 in this way, the thermal conductive sheet 100 having the thickness t is transformed into the thermal conductive sheet 100 having a relatively thin thickness t1. For example, a thermal conductive sheet 100 having a thickness t of 1.05 to 1.3 mm is transformed into a thermal conductive sheet 100 having a thickness t1 of approximately 1 mm. (Seat surface processing process; S80)

In this way, the thermal conductive sheet 100 whose surface treatment has been completed through the sheet surface processing step (S80) is cut into products of various specifications using a device such as a Thomson cutter or a high-speed punching machine, so that the thermal conductive sheet 100 production is complete. (Sheet cutting process; S90)

In the manufacturing method of the thermally conductive sheet having the above structure, a liquid thermally conductive composition (M) containing a polymer (3), an anisotropic thermally conductive filler (1) and a filler (2) is discharged to the outside in a first step. A liquid raw material ejector 200 including a discharge port 230 extending along the central axis C1 and a molding mold 240 accommodating the liquid discharge material M discharged from the discharge port 230. As a method of manufacturing a thermal conductive sheet using, the discharge from the discharge port 230 is performed by reciprocating the relative position between the discharge port 230 and the forming mold 240 several times along the second central axis C2. A liquid raw material discharge step (S40) of accommodating the liquid discharge material (M) being extended by a predetermined length along the second central axis (C2) into the molding mold 240; A molding stabilization step (S50) of exposing the liquid ejection material (M) accommodated in the molding mold 240 to a predetermined temperature for a predetermined time through the liquid raw material discharging process (S40); A molding curing step (S60) of obtaining a cured molding (S1) by curing the discharge material (M) stabilized through the molding stabilization step (S50) at a predetermined temperature for a predetermined time; The cured molding (S1) cured through the molding curing process (S60) is cut in a cutting direction intersecting the second central axis (C2) to obtain a sheet 100 having a predetermined thickness (t). Since it includes a cutting process (S70), unlike the conventional manufacturing method in which the diameter of the sheet base material is limited due to the limitations of extrusion itself, if only the size of the molding mold 240 is increased, a separate pressing process or bonding process Without, there is an advantage in that a large-sized thermal conductive sheet 100 can be easily manufactured, and rapid mass production is easy.

In the manufacturing method of the thermal conductive sheet, in the liquid raw material discharging step (S40), the discharge port 230 reciprocates multiple times along the second central axis C2 with respect to the forming mold 240. while moving relative to the mold 240 along the third central axis C3 intersecting the second central axis C2, the liquid discharged material M discharged from the discharge port 230 Since it covers at least a part of the entire area of the mold for molding 240, the mold for molding 240 has a lump form including the discharged material of the plurality of layers M1, M2, M3, M4, and M5. There is an advantage in that it is easy to form the laminated discharge material MS.

In addition, in the manufacturing method of the thermal conductive sheet, in the liquid raw material discharging step (S40), the discharge port 230 reciprocates multiple times along the second central axis C2 with respect to the forming mold 240. while moving relative to the molding mold 240 along the third central axis C3 intersecting the second central axis C2, so that the relative movement occurs in a zigzag form, as shown in FIG. There is an advantage in that the discharged materials M1 of the dog lines can be closely attached to each other to uniformly and quickly cover the entire area of the bottom portion 241 without gaps.

And, in the method of manufacturing the thermal conductive sheet, in the liquid raw material discharging step (S40), the liquid discharged material M discharged from the discharge port 230, as shown in FIG. 3, the molding mold 240 ), since it is discharged in a state in which multiple layers (M1, M2, M3, M4, and M5) are stacked, the cuboid rod-shaped lumps and discharged material (MS) as shown in FIG. It has the advantage of being quick to acquire.

In addition, in the manufacturing method of the thermally conductive sheet, since the molding mold 240 has a rectangular parallelepiped-shaped inner space 243 extending along the second central axis C2, and the upper end is open, As shown in FIG. 1, the discharge port 230 of the liquid raw material ejector 200 is disposed above the molding mold 240 to vertically drop the discharged material M into the molding mold 240. There are advantages to injecting.

In addition, the manufacturing method of the thermally conductive sheet may include: a cylinder 210 in which the liquid raw material discharger 200 accommodates the liquid thermally conductive composition M therein; A piston 220 reciprocating inside the cylinder 210; and since the discharge port 230 is provided at one end of the cylinder 210, the liquid raw material discharger 200 having a relatively simple configuration There is an advantage in that the liquid thermally conductive composition (M) can be discharged at a uniform pressure and speed.

In addition, in the manufacturing method of the thermal conductive sheet, since the discharge port 230 includes a pipe-shaped member having an inner diameter (d) of 1 to 5 mm, as shown in FIG. There are advantages to letting go.

And, in the manufacturing method of the thermal conductive sheet, since the liquid discharge material M discharged from the discharge port 230 has a viscosity of 100,000 to 1,000,000 cPs, while maintaining the orientation of the anisotropic thermal conductive filler 1, the internal There is an advantage in obtaining a laminated ejection material (MS) without bubbles (G).

In addition, the method of manufacturing the thermal conductive sheet further includes a sheet surface processing step (S80) of smoothing the surface of the sheet 100 prepared to have a predetermined thickness in the molding cutting step (S70) to a predetermined roughness or less. Since it includes, there is an advantage in that durability and tack property of the thermally conductive sheet 100 can be increased by smoothly processing a surface roughly cut by the ultrasonic cutter 400 .

And, in the method of manufacturing the thermally conductive sheet, in the sheet surface processing step (S80), the sheet 100 is formed along the thickness direction of the sheet 100 using a press forming machine 300 as shown in FIG. By pressing, since the surface of the sheet 100 is processed smoothly, there is an advantage in that the sheet surface processing step (S80) can be quickly performed.

On the other hand, in the manufacturing method of the thermal conductive sheet, since the polymer 3 includes a silicone resin, the thermal conductive sheet 100 has excellent molding processability and weather resistance, and excellent adhesion and followability to electronic parts. There are advantages.

In addition, in the manufacturing method of the thermally conductive sheet, since the filler 2 includes at least one of aluminum oxide, aluminum nitride, zinc oxide, silicon powder, and metal powder, the thermally conductive sheet 100 having excellent thermal conductivity is manufactured. There are advantages to doing so.

And, in the manufacturing method of the thermal conductive sheet, since the filler 2 includes spherical aluminum oxide particles having an average particle diameter of 0.1 μm to 45 μm, the thermal conductive sheet 100 having excellent thermal conductivity and filling property can be manufactured. There are advantages to being able to

In addition, in the manufacturing method of the thermally conductive sheet, since the content of the filler 2 in the thermally conductive composition is 20% to 40% by volume, the thermally conductive sheet 100 having appropriate flexibility and thermal conductivity can be manufactured. There are advantages.

And, in the manufacturing method of the thermally conductive sheet, since the content of the anisotropic thermally conductive filler 1 in the thermally conductive composition is 20 vol% to 50 vol%, while imparting sufficient thermal conductivity to the molded article, moldability and orientation at the same time There is an advantage of being able to manufacture this excellent thermal conductive sheet 100.

In addition, in the manufacturing method of the thermally conductive sheet, the anisotropic thermally conductive filler 1 is selected from the group consisting of boron nitride (BN) powder, graphite, carbon fiber, and carbon nanotube (CNT). Since it includes at least one, there is an advantage of being able to manufacture a thermally conductive sheet 100 having excellent thermal conductivity and durability.

In this embodiment, the discharge port 230 includes a pipe-type member having a circular cross section, but may also include a pipe-type member having a cross section of an arbitrary shape such as a rectangle or a square.

Although the present invention has been described above, the technical scope of the present invention is not limited to the contents described in the above-described embodiments, and an equivalent configuration modified or changed by a person skilled in the art is the technical scope of the present invention. It is clear that it does not deviate from the scope of ideas.

＊ Description of symbols for main parts of drawings ＊
1: anisotropic thermally conductive filler
2: filler
3: polymer
100: thermal conductive sheet
200: liquid raw material ejector
210: cylinder
220: piston
230: discharge port
240: mold for molding
241: bottom
242: side wall
243: inner space
300: press molding machine
310: pressing member
320: mold member
400: ultrasonic cutter
A: Fore-and-aft direction
B: left and right direction
C: vertical direction
G: air bubbles
M, M1, M2, M3, M4, M5: thermally conductive composition, exudate
MS: laminated discharge
P: pressing direction
S: laminated molding
S1: cured molding
V: vibration direction

Claims (16)

A mold for molding that accommodates a discharge port extending along the first central axis as a portion through which a liquid thermal conductive composition containing a polymer, an anisotropic thermal conductive filler, and a filler is discharged to the outside, and a liquid discharged product discharged from the discharge port. A method for manufacturing a thermally conductive sheet using a liquid raw material ejector comprising:
By reciprocating the relative position between the discharge port and the mold for molding multiple times along the second central axis, the liquid discharge material discharged from the discharge port is extended by a predetermined length along the second central axis, and the mold for molding a step of discharging a liquid raw material to be accommodated in;
a molded product stabilization step of exposing the liquid discharged material accommodated in the molding mold through the liquid raw material discharging process to a predetermined temperature for a predetermined time;
a molding curing step of obtaining a cured molding by curing the discharge material stabilized through the molding stabilization step at a predetermined temperature for a predetermined time;
manufacturing a thermal conductive sheet comprising a; molding cutting step of obtaining a sheet having a predetermined thickness by cutting the cured molding cured through the molding curing step in a cutting direction intersecting the second central axis; Way. According to claim 1,
In the liquid raw material discharging process,
While the discharge port reciprocates several times along the second central axis with respect to the molding mold, the discharge port is discharged from the discharge port by relative movement along a third central axis intersecting the second central axis with respect to the molding mold. A method of manufacturing a thermally conductive sheet, characterized in that the liquid ejected material covers at least a part of the entire area of the molding mold. According to claim 2,
In the liquid raw material discharging process,
The discharge port moves relative to the mold for molding along a third central axis intersecting the second central axis while reciprocating multiple times along the second central axis with respect to the molding mold, thereby relatively moving in a zigzag pattern. A method for manufacturing a thermally conductive sheet, characterized in that for doing. According to claim 2,
In the liquid raw material discharging process,
The method for manufacturing a thermally conductive sheet according to claim 1 , wherein the liquid discharged material discharged from the discharge port is discharged in a state in which a plurality of layers are stacked on the molding mold. According to claim 1,
The method of manufacturing a thermally conductive sheet, characterized in that the molding mold has a rectangular parallelepiped-shaped inner space extending along the second central axis, and an upper end portion is open. According to claim 1,
The liquid raw material discharger,
a cylinder accommodating the liquid thermally conductive composition therein; A piston capable of reciprocating movement inside the cylinder;
The method of manufacturing a thermally conductive sheet, characterized in that the discharge port is provided at one end of the cylinder. According to claim 1,
The method of manufacturing a thermally conductive sheet, characterized in that the discharge port comprises a pipe-shaped member having an inner diameter of 1 to 5 mm. According to claim 1,
The method of manufacturing a thermally conductive sheet, characterized in that the liquid discharged from the discharge port has a viscosity of 100,000 to 1,000,000 cPs. According to claim 1,
The manufacturing method of the thermally conductive sheet, characterized in that it further comprises a sheet surface processing step of smoothly processing the surface of the sheet prepared to have a predetermined thickness in the molding cutting step to a predetermined roughness or less. According to claim 9,
In the sheet surface processing step,
A method for manufacturing a thermally conductive sheet, characterized in that the surface of the sheet is smoothed by pressing the sheet along the thickness direction of the sheet using a press molding machine. According to claim 1,
The method of manufacturing a thermally conductive sheet, characterized in that the polymer comprises a silicone resin. According to claim 1,
The method of manufacturing a thermally conductive sheet according to claim 1 , wherein the filler includes at least one of aluminum oxide, aluminum nitride, zinc oxide, silicon powder, and metal powder. According to claim 1,
The method for producing a thermally conductive sheet according to claim 1 , wherein the filler includes spherical aluminum oxide particles having an average particle diameter of 0.1 μm to 45 μm. According to claim 1,
The method for producing a thermally conductive sheet according to claim 1 , wherein the content of the filler in the thermally conductive composition is 20% by volume to 40% by volume. According to claim 1,
The method for producing a thermally conductive sheet according to claim 1 , wherein the content of the anisotropic thermally conductive filler in the thermally conductive composition is 20 vol% to 50 vol%. According to claim 1,
The anisotropic thermally conductive filler of the thermally conductive sheet, characterized in that it contains at least one selected from the group consisting of boron nitride (BN) powder, graphite, carbon fiber, carbon nanotube (CNT) manufacturing method.

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