TW201606037A - Enhanced pressure sensitive adhesive for thermal management applications - Google Patents

Abstract

An enhanced pressure sensitive adhesive film includes a filler dispersed within an acrylic polymer matrix. The filler has an average particle size less than the thickness of the pressure sensitive adhesive layer, and is selected from graphite, boron nitride, aluminum oxide and zinc oxide.

Description

Enhanced pressure sensitive adhesive for thermal management applications

Provided herein are enhanced pressure sensitive adhesive films for thermal management applications.

Thermal management materials for dissipating heat generated by electronic components within the device are well known. Conventional pressure sensitive adhesives (PSAs), such as acrylic based PSAs, are known to provide a means of attaching a heat dissipating material to an electronic component. However, acrylic based PSA is generally avoided because of the poor thermal conductivity across the acrylic substrate. Although thermally conductive PSA is commercially available, it typically has a thickness of from 75 [mu]m to 150 [mu]m to fill any surface voids or gaps between the glue lines. These thermally conductive PSAs are not suitable for increasingly smaller electronic devices that have limited space and require improved thermal management solutions. Also, thermal solutions for electronic devices have avoided laminated heat sink materials with conventional PSAs.

Although some PSAs are electrically conductive to ever smaller electronic devices, they are not optimally designed for thermal management. For example, commercially available conductive PSA films are typically not highly filled and the filler particles span the thickness of the film. Although the conductive PSAs are designed to maximize electrical conduction in the z-direction, the PSAs are not optimized for thermal management.

The graphite heat sink provides a thin, flexible, lightweight film with high thermal conductivity for use with PSA. Most of the focus is on the uniqueness of thermal reforms. New heat-dissipating films are difficult to manufacture, expensive, and limited to certain heat-dissipating materials. Other thermal solutions focus on software and redesign devices.

There is a need in the industry to overcome the shortcomings and limitations of PSA for thermal management in electronic devices. The present invention satisfies this need.

One aspect of the present invention relates to a pressure-sensitive adhesive film comprising a filler dispersed in an acrylic polymer matrix, and the filler has an average particle size smaller than the thickness of the pressure-sensitive adhesive film. The filler is selected from the group consisting of graphite, boron nitride, aluminum oxide, and zinc oxide. In one embodiment of the PSA film, the PSA film has a thickness of less than 15 [mu]m and the filler comprises from 5% to 95% by weight of the PSA film. In another embodiment, the PSA film has a thickness of less than 10 [mu]m and the filler comprises from 10% to 80% by weight of the film. In another embodiment, the filler is graphite and the PSA film has a thermal conductivity between 1 W/mK and 3 W/mK.

In another aspect, the invention is directed to a heat dissipating laminate comprising two or more heat dissipating layers and a PSA film disposed between the heat dissipating layers. The PSA film comprises a filler dispersed in an acrylic polymer matrix. The filler has an average particle size less than the thickness of the film, and the filler is selected from the group consisting of graphite, boron nitride, aluminum oxide, and zinc oxide. In one embodiment of the laminate, the PSA film has a thickness of less than 15 [mu]m and the filler comprises from 5% to 95% by weight of the PSA layer. In another embodiment of the laminate, the film has a thickness of less than 10 [mu]m and the filler comprises from 10% to 80% by weight of the film. In still another embodiment of the laminate, the filler is graphite and the PSA film has a thermal conductivity of between 1 W/mK and 3 W/mK. In another embodiment of the laminate, the heat dissipation layer is selected from the group consisting of synthetic graphite, natural graphite, aluminum, and copper foil. In still another embodiment of the laminate, the heat dissipation layer comprises synthetic graphite having a thickness of between 5 μm and 25 μm.

Another aspect of the invention includes a method of making a pressure sensitive adhesive film comprising providing a release liner; and placing a pressure sensitive adhesive film on the release liner. The PSA film comprises a filler dispersed in an acrylic polymer matrix, the filler having an average particle size smaller than the thickness of the film, and wherein the filler is selected from the group consisting of graphite, boron nitride, Alumina and zinc oxide. In a particular embodiment, the thickness of the film is less than 15 [mu]m and the filler comprises from 5% to 95% by weight of the film.

Another aspect of the invention pertains to electronic articles comprising a heat dissipating material, an electronic component, and a pressure sensitive adhesive (PSA) film. The PSA film is placed between the heat sink material and the electronic components. The PSA film comprises a filler dispersed in an acrylic polymer matrix, and the filler has an average particle size smaller than the thickness of the PSA film. The filler is selected from the group consisting of graphite, boron nitride, aluminum oxide, and zinc oxide.

In still another embodiment of the electronic article, the heat dissipating material is selected from the group consisting of synthetic graphite, natural graphite, aluminum, and copper foil. In another embodiment of the electronic article, the heat dissipating material comprises synthetic graphite having a thickness of between 5 μm and 25 μm. In still another embodiment of the electronic article, the electronic component is selected from the group consisting of: a bulk microchip, a microprocessor, a transistor, a diode, a relay, a resistor, a transformer, an amplifier, and an EMI Shielding and capacitors, and wherein the electronic components have an operating temperature of between 15 ° C and 100 ° C.

In another aspect, the invention is directed to an electronic article comprising a housing comprising at least one substrate. The substrate is proximate to at least one of the heat generating electronic components. The PSA film is placed on the substrate. The PSA film comprises a filler dispersed in an acrylic polymer matrix. The filler has an average particle size less than the thickness of the PSA film, and the filler is selected from the group consisting of graphite, boron nitride, aluminum oxide, and zinc oxide.

In one embodiment of the electronic article, the PSA film has a thickness of less than 15 [mu]m and the filler comprises from 5% to 95% by weight of the film. In another embodiment of the electronic article, the thickness of the film is less than 10 [mu]m and the filler comprises from 10% to 80% by weight of the film. In still another embodiment, the filler is graphite and the film has a thermal conductivity of between 1 W/mK and 3 W/mK. In another embodiment, the electronic article further includes a heat dissipating material disposed in contact with the film, and the heat dissipating material is selected from the group consisting of: synthetic graphite, natural graphite, aluminum, and copper foil. In another embodiment, the electronic article further includes being placed in contact with the PSA film The heat dissipating material is touched, and the heat dissipating material comprises synthetic graphite having a thickness of between 5 μm and 25 μm. In another embodiment, the electronic component is selected from the group consisting of an integrated microchip, a microprocessor, a transistor, a diode, a relay, a resistor, a transformer, an amplifier, an EMI shield, and a capacitor, and an electronic component It has an operating temperature between 15 ° C and 100 ° C.

As noted above, an enhanced pressure sensitive adhesive (PSA) film is provided herein. The PSA film comprises a filler dispersed in an acrylic polymer matrix, and the filler has an average particle size smaller than the thickness of the PSA film. In an embodiment, the PSA film is placed between the heat sink material and the electronic component.

Also provided herein are electronic articles comprising a housing comprising at least one substrate. The substrate is adjacent to at least one of the heat generating electronic components, and the PSA film is placed on the substrate. The PSA film comprises a filler dispersed in an acrylic polymer matrix. The filler has an average particle size that is less than the thickness of the PSA film.

In still another aspect, the present invention is directed to a heat dissipating laminate comprising two or more heat dissipating layers and a PSA film disposed between the heat dissipating layers. The PSA film comprises a filler dispersed in an acrylic polymer matrix. The filler has an average particle size that is less than the thickness of the film.

The PSA film composition comprises a filler dispersed in a PSA matrix. The filler can be thermally and electrically conductive. Alternatively, it can be thermally and electrically insulated. The thermally conductive filler may comprise a metal filler, an inorganic filler, or a combination thereof.

The metal filler includes metal particles and metal particles having a layer on the surface of the particles. The layers can be, for example, metal nitride layers or metal oxide layers on the surface of the particles. Suitable metal fillers are, for example, particles selected from the group consisting of aluminum, copper, gold, nickel, tin, silver, and combinations thereof. Suitable metal fillers further have, for example, on their surface selected from the following The particles of the metal listed above in the layer of the composition: aluminum nitride, aluminum oxide, boron nitride, zinc oxide, magnesium oxide, copper oxide, nickel oxide, silver oxide, and combinations thereof. For example, the metal filler may include aluminum particles having an aluminum oxide layer on the surface thereof.

Inorganic fillers are, for example, metal oxides such as alumina, cerium oxide, magnesium oxide and zinc oxide; nitrides such as aluminum nitride and boron nitride; diamond, natural graphite, synthetic graphite, single layer graphite, carbon black, carbon fiber , carbon nanotubes, graphite fibers, diamond powder, boron nitride nanotubes and combinations thereof.

The shape of the thermally conductive filler particles is not particularly limited, however, the circular or spherical particles prevent the viscosity from increasing to an undesired value after loading a high content of the thermally conductive filler in the composition. The average particle size of the thermally conductive filler will depend on various factors, including the type of thermally conductive filler selected for the PSA and the exact amount added to the curable composition, as well as the electronic components and/or heat sinks that will use the cured product of the composition. Glue line thickness of PSA between materials.

The filler may have an average particle size that is less than the thickness of the pressure sensitive adhesive layer. In one embodiment, the filler is dispersed in a PSA film that is less than 15 microns thick and the filler has an average particle size that is less than the thickness of the PSA film. In another embodiment, the filler is dispersed in a PSA film that is less than 10 microns thick and the filler has an average particle size that is less than the thickness of the PSA film.

The thermally conductive filler may be a single thermally conductive filler or a combination of two or more thermally conductive fillers in at least one such as particle shape, average particle size, particle size distribution, and filler type. The aspects are different. In an embodiment, the combination of metal and inorganic filler provides increased thermal conductivity.

In embodiments, thermally conductive filler materials of different sizes may be used, for example, a combination of graphite having a larger average particle size and graphite having a smaller average particle size. Alternatively, it may be desirable to use a combination of metal fillers, such as boron nitride having a larger average particle size and graphite having a smaller average particle size. Using a first filler having a larger average particle size and a second filler having an average particle size smaller than the first filler can improve packaging efficiency and can be reduced Viscosity and enhanced heat transfer.

The amount of thermally conductive filler in the PSA composition will depend on various factors including the cure mechanism selected for the composition, the selected thermally conductive filler, and the desired strength of the PSA. In an embodiment, the filler may be selected from the group consisting of graphite, boron nitride, aluminum oxide, and zinc oxide.

Commercially representative examples of suitable thermally conductive fillers include graphite, boron nitride, and zinc oxide as exemplified in the examples.

Pressure sensitive adhesive

The thermally conductive filler is dispersed in a matrix which may be a pressure sensitive adhesive. The PSA is made of an acrylic polymer, for example, having the following composition or can be prepared by polymerizing: (i) having the formula CH ₂ =CH(R ¹ ) ( An acrylic monomer of an acrylic or methacrylic acid derivative (e.g., methacrylate) of COOR ² ) wherein R ¹ is H or CH ₃ and R ² is C _1-20 , preferably C _1-8 alkyl And (ii) a monomer having pendant reactive functional groups as set forth in more detail below, and the amount of monomer (ii) is from about 0.001 equivalents to about 0.015 equivalents per 100 grams of acrylic polymer.

For the polymerization process, the monomers of components (i) and (ii), if appropriate, are converted to acrylic polymers by free radical polymerization. The monomers are selected such that the resulting polymer can be used to prepare PSA according to "Handbook of Pressure Sensitive Adhesive Technology" by D. Satas (van Nostrand, NY (1989)).

Examples of the acrylate and/or methacrylate which can be used as the component of the monomer mixture (i) include methyl acrylate, ethyl acrylate, ethyl methacrylate, methyl methacrylate, n-butyl acrylate, N-butyl methacrylate, n-amyl acrylate, n-hexyl acrylate, n-heptyl acrylate and n-octyl acrylate, n-decyl acrylate, lauryl methacrylate, cyclohexyl acrylate and branched (methyl) Acrylic isomers such as isobutyl acrylate, isobutyl methacrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, octadecyl methacrylate and isooctyl acrylate.

An exemplary acrylic monomer mixture (i) has a Tg value of less than 0 ° C and from about 10,000 A weight average molecular weight of from g/mol to about 2,000,000 g/mol (for example between 50,000 g/mol and 1,000,000 g/mol and desirably between 100,000 g/mol and 700,000 g/mol). Mixture (i) can be a single monomer having a homopolymer Tg of less than 0 °C in the former system.

Examples of suitable monomers (ii) are those capable of providing green strength to the adhesive film, including cycloaliphatic epoxy monomers M100 and A400 (Daicel), oxetane monomer OXE-10 (available from Kowa Corporation). Dicyclopentadienyl epoxide epoxide (CD535, available from Sartomer, Inc., Exton, Pa.), and 4-vinyl-1-cyclohexene-1,2- Epoxide (available from Dow).

The acrylic polymer is capable of withstanding the reaction of cation activation after ultraviolet light and thus provides a high temperature holding strength to the adhesive film. The acrylic polymer may have the following composition or may be prepared by polymerizing: (i) an acrylic acid or methacrylic acid derivative having the formula CH ₂ =CH(R ₁ )(COOR ₂ ) An acrylic monomer, wherein R ₁ is H or CH ₃ and R ₂ is a C _1-20 alkyl chain; and (ii) a monomer having a combination of pendant reactive functional groups selected from the group consisting of: (1) a cycloaliphatic epoxide, oxetane, benzophenone or mixtures thereof, and (2) a monosubstituted ethylene oxide. The amount of the monomer (ii) is from about 0.001 equivalents to about 0.015 equivalents per 100 g of the acrylic polymer. The acrylic polymer is essentially free of multiple (meth) acrylate, polyol or OH functional groups and the polymer remains substantially linear after polymerization. In a more preferred embodiment, the amount of monomer (ii) is from about 0.002 equivalents to about 0.01 equivalents per 100 grams of acrylic polymer.

The acrylic polymer produced typically has a weight of from 10,000 g/mol to 2,000,000 g/mol (eg, between 50,000 g/mol and 1,000,000 g/mol, such as between 100,000 g/mol and 700,000 g/mol). Average average molecular weight (M _w ). M _w is determined by gel permeation chromatography or matrix-assisted laser desorption/ionization mass spectrometry.

Examples of the monosubstituted ethylene oxide which can be used as the monomer (ii) include glycidyl methacrylate, 1,2-epoxy-5-hexene, glycidyl 4-hydroxybutyl acrylate, and cycloaliphatic Group epoxy monomers M100 and A400, OXE-10, CD535 epoxide and 4-vinyl-1-cyclohexene - 1,2-epoxide.

The PSA may also contain various other additives such as plasticizers, tackifiers, and fillers, all of which are conventionally used in the preparation of PSA. As the plasticizer to be added, a low molecular weight acrylic polymer, a phthalate ester, a benzoate, an adipate or a plasticizer resin has a slight possibility. It is possible to use any of the known tackifying resins described in the literature as the tackifier or tackifying resin to be added. Non-limiting examples include terpene resins, oxime resins and their disproportionated, hydrogenated, polymerized and esterified derivatives and salts, aliphatic and aromatic resins, terpene resins, terpene phenol resins, C ₅ resins, C ₉ Resins, and other hydrocarbon resins. Any desired combination of these or other resins can be used to tailor the properties of the resulting adhesive to the desired final properties.

The PSA can be further blended with one or more additives such as antioxidants, antioxidants, light stabilizers, complexing agents, and/or accelerators.

Commercially representative examples of suitable PSAs include those available from Henkel under the trade name DUROTAK.

Generally, the thermal conductivity of conventional PSA ranges from 0.1 W/mK to 0.25 W/mK. The thermally enhanced PSA can increase the thermal conductivity from 0.25 W/mK to 20 W/mK, and even more specifically from 0.5 W/mK to 10 W/mK.

The thermally enhanced PSA composition can be placed on the inner surface of the coating and/or outer shell of the release layer or at least a portion of the electronic component.

The thickness of the PSA film is sufficient to aid in the creation of a bond for heat transfer through the film, but is not thick enough to interfere with the assembly and/or operation of the electronic device.

In one embodiment, the viscosity of the liquid-enhanced PSA is in the range of 15 cp to 15,000 cp and more preferably 300 cp to 3000 cp. The thickness of the thermally enhanced PSA in the dried film can range from 2 microns to 30 microns, and more preferably from 3 microns to 15 microns, and even more preferably from 5 microns to 12 microns. The adhesion at 180° peel strength can range from 8 lbf/in to 100 lbf/in, and even more preferably from 10 lbf/in to 70 lbf/in. In a particular embodiment, the filler system The graphite and PSA layer has a thermal conductivity of between 1 W/mK and 3 W/mK.

In another embodiment, the coating is less than 15 microns thick and the thermally conductive filler in the PSA is from 5% to 95% by weight. In another embodiment, the coating is less than 10 microns thick and the thermally conductive filler in the PSA is from 10% to 80% by weight.

In a particular embodiment, the filler is dispersed in a PSA film that is less than 15 microns thick, the filler is graphite and has an average particle size less than the thickness of the PSA film, and the filler comprises 5% by weight of the liquid PSA prior to evaporation of the PSA solvent. Up to 35% by weight, and the PSA film has a thermal conductivity of between 1 W/mK and 3 W/mK. In an even more specific embodiment, the filler is dispersed in a PSA film that is less than 10 microns thick, the filler is graphite and has an average particle size less than the thickness of the PSA film, and the filler occupies the liquid PSA prior to evaporation of the PSA solvent. 10% by weight to 30% by weight, and the PSA film has a thermal conductivity of between 1 W/mK and 3 W/mK.

Heat sink material

To effectively manage the heat generated by electronic components, the heat sink material transfers heat to a passive or active heat sink. Heat is applied directly to the environment using a heat sink applied to the low power device (eg, semiconductor and EMI shielding in the mobile device) to the enclosure or to another region away from the hot spot. On high power devices (such as CPUs), the heat sinks dissipate heat to the active cooling device.

A variety of heat sinks are available for different applications. The heat sink can be made of a solid thermally conductive metal. Copper and aluminum are the most commonly used metals due to their high thermal conductivity and low cost. The disadvantage of copper is its high density and coefficient of thermal expansion (TCE), which prevents direct attachment to the germanium grains. Aluminum provides high thermal conductivity, low density, and ease of manufacture, but its (TCE) is also higher than 矽. Thermally conductive ceramics (such as BeO, AlN, and SiC) have high thermal conductivity and low TCE compared to aluminum and copper. The thickness of the heat dissipating material can range from 5 microns to 500 microns.

Natural and synthetic graphite can be used as the heat dissipating material, and the advantage is that the density of graphite is 1/5 of that of copper. Natural graphite isotropic material, which is raised on the plane of the diffuser (x-y axis) A thermal conductivity of about 140 W/mK to 500 W/mK is provided, and a lower thermal conductivity of about 3 W/mK to 10 W/mK across the plane (z-axis) across the spreader thickness. Synthetic graphite provides a thermal conductivity of from about 600 W/mK to about 1750 W/mK in the plane of the diffuser. Graphite heat sinks are particularly useful in electronic applications where heat flux density is low, such as electronic applications with memory modules and portable electronics.

In an embodiment, the heat sink is a graphite sheet or a metal foil. In a particular embodiment, the heat sink is formed from flexible synthetic graphite, natural graphite, and combinations thereof. The thickness of the synthetic or natural graphite can range from 5 microns to 45 microns. In a particular embodiment, the heat dissipating material is synthetic graphite having a thickness of between 5 μm and 25 μm. The thickness of the copper foil heat sink material can range from 15 microns to 250 microns.

Commercially representative examples of suitable heat sinks include synthetic graphite from Qingdao and pyrolytic graphite from Panasonic.

Electronic component

The electronic component can include any subassembly that produces sufficient heat to interfere with the operation of the electronic component or the system in which the electronic component is a component if not dissipated. Electronic components can include microprocessors or computer chips, integrated circuits, electronic controls for optical devices such as lasers or field effect transistors (FETs). In an embodiment, the electronic component is selected from the group consisting of: a bulk microchip, a microprocessor, a transistor, a diode, a relay, a resistor, a transformer, an amplifier, an EMI shield, and a capacitor. The electronic component includes at least one surface from which heat is radiated and can be used as a source of heat to be dissipated from the electronic component. In an embodiment, the electronic component has an operating temperature of between 15 °C and 100 °C.

Electronic components, reinforced pressure sensitive adhesives and heat sinking materials can be used in the assembly of electronic objects. The object (or "device") can be selected from a notebook personal computer, a tablet personal computer or a handheld device, such as a music player, a video player, a still video player, a game console, other media players, a music recorder. , video recorders, cameras, other media recorders, radios, medical equipment, household appliances, transport vehicles, musical instruments, meters Calculators, mobile phones, other wireless communication devices, personal digital assistants, remote controls, pagers, monitors, televisions, stereo devices, set up boxes, frequency converters, music boxes, data sets, Routers, keyboards, mice, speakers, printers, and combinations thereof.

The device includes an outer casing having at least one surface that approximates and/or encloses at least one heat generating component. The outer casing can be made of plastic, metal or any suitable metal. The outer casing may be formed from a single piece of material or from multiple pieces of material. The outer casing can include sub-assemblies including outer and inner claddings, structural supports, fasteners, and intermediate frames. In an embodiment, the shield intermediate frame is placed close to the electronic components on the same or different printed circuit boards (PCGs). The outer casing can be adapted to promote heat dissipation or distribution.

Preparation

An electronic device assembled with an enhanced PSA can be prepared by dispersing a thermally conductive filler into a liquid PSA resin system. The resin system can include an aqueous or solvent based acrylic PSA. The liquid solution is then applied or applied to a first surface (eg, a heat dissipating material, an electronic component) or an outer casing of the electronic device. The solution is then dried to remove the solvent leaving a film of reinforced PSA. This solution can also be applied to a release liner (e.g., a polyoxo-treated release liner) and then dried to remove solvent to produce a thinned transfer tape format of the enhanced PSA. The reinforced PSA can then be applied to a second surface (eg, a heat dissipating material, an electronic component) or a cladding of an electronic device. In an embodiment, the enhanced PSA is applied to a heat dissipating material. In another embodiment, the enhanced PSA is applied to an outer casing within the electronic device.

The thermally conductive heat-dissipating laminate can be formed by dispersing a thermally conductive filler into a liquid PSA resin system. The resin system can include a water based or solvent based solution acrylic PSA. The liquid solution is then applied or applied to the first heat sink material. The solution is then dried to remove the solvent leaving a film of the enhanced pressure sensitive adhesive. This solution can also be applied to a release liner and then dried to remove solvent to produce a thin transfer ribbon format for thermally conductive PSA. The reinforced PSA can then be applied to the second heat sink material to form a thermally conductive heat sink laminate. An additional layer of heat sinking material can be added by inserting a thin film of thermally conductive PSA in between. Enhanced PSA can be encapsulated Heat sink material. Advantageously, a stronger and more durable laminated heat sink is formed when an additional layer is applied using the intervening thermally conductive PSA.

Instance Example 1

The ingredients listed in Table 1 below were placed in a vessel while mixing at high speed to form a mixture.

¹ average particle size 0.12 μm, surface area 9.0 m ² /g 9.0, apparent density 0.64 g/cm ³ .

² object size d50 2.2μm. The surface area was 21.0 m ² /g, and the knocking tightness was 0.30 g/cm ³ .

^3, an average particle size of 0.9 μm, a surface area of 20.0 m ² /g, and a knock tightness of 0.12 g/cm ³ .

⁴ particle size d50 2.4 μm, d90 4.1 μm, surface area 26.0 m ² /g, density 0.07 g/cm ³ .

⁵ particle size d50 2.6 μm, d90 5.0 μm, surface area 352 m ² /g, true density 2.16 g/cm ³ .

⁶ particle size d50 5.2 μm, d90 12 μm.

Each mixture was stirred for 2 minutes to disperse the thermally conductive filler and form a numbered sample. Then, each mixture is applied to the release liner of the polyoxygen treatment using a pull-down bar and Drying at 90 ° C for 15 minutes to produce a viscous, heat-reinforced PSA film of about 5 μm to 10 μm. Then, each of the reinforced PSA films was transferred and laminated into a synthetic graphite sheet (25 um Qingdao, cut into a size of 50 x 55 mm). 5 μm PET was laminated on the side of the graphite not covered with PSA to produce a complete heat sink film. The film is then removed from the carrier release liner and the exposed PSA film is adhered to the surface of the thermal test die that simulates the electronic components encapsulated in the electronic device.

In Table 2 below, sample numbers 1 through 8 were adhered to the surface of the thermal test die and the junction temperature was recorded at several time intervals as shown in the leftmost row. As the heat generated by the test die, it spreads through the PSA and into the graphite flakes.

The results of the samples were compared to the results obtained with unfilled samples of control, PSA coated graphite sheets. It was found that the heat dissipation performance of the enhanced film was as high as 1.4 ° C compared with the conventional PSA. See, for example, sample 7 versus control at 1800 second intervals.

Example 2

The components of sample numbers 1 to 15 listed in Table 3 below were placed in a vessel under high speed dispersion mixing to form a mixture.

¹ particle size d50 3.68 μm, surface area 14.49 m ² /g.

² Panasonic PGS graphite is illustrated as a pyrolytic graphite sheet having the following dimensions: 10 μm PET, 17 μm graphite, 10 μm conventional PSA for a total thickness of 37 μm. The graphite sheet was described to have a density of 2.10 g/cm ³ and a thermal conductivity of 1750 W/mK along the xy axis.

³ Dasen DSN5025PM-5 is illustrated as a synthetic graphite film having the following dimensions: for a total thickness of 35 μm, 5 μm PET, 25 μm graphite, 5 μm conventional PSA. This film was applied to a 75 μm PET release liner. To apply to the test dies, a 75 [mu]m PET release liner was removed and discarded, and a PSA film was applied to the test dies. The graphite sheet is illustrated to have a density of 1.6-1.8 g/cm ³ and a thermal conductivity along the xy axis such as 1500 W/mK to 1700 W/mK and the z-axis 15 W/mK to 20 W/mK.

Each mixture was stirred for 2 minutes to disperse the thermally conductive filler and form a numbered sample. Then, each mixture was applied to a polyfluorene-treated release liner using a drawdown bar and dried at 121 ° C for 15 minutes to produce a viscous, heat-reinforced PSA film of about 5 μm to 10 μm. Then, each reinforced PSA film was transferred into a synthetic graphite sheet (25 um Dasen, having the same dimensions as in Example 1), and 5 μm PET was laminated on the side of the graphite not covering the PSA to produce complete heat dissipation. Film. The film was then released from the carrier release liner of the film and the surface with the PSA film adhered to the surface of the thermal test die for evaluation.

Two commercially available graphite heat sink films (Panasonic PGS graphite ("PGS") and Dasen DSN5000 graphite ("DSN")) were used as controls to compare with the enhanced PSA. The nature of the control is set forth in Table 1 and similarly cut to a size of 50 x 55 mm. Remove the release layer.

In Table 4 below, sample numbers 1 through 15 and two controls were adhered to the surface of the thermal test die and the last junction temperature after the 30 minute test time was recorded.

The results of the two controls with the conventional PSA/graphite heat sink were compared to samples containing the reinforced PSA/graphite heat sink. The thermally enhanced PSA was found to provide improved heat dissipation of 3-7 °C compared to the two controls coated with conventional adhesives.

Claims (19)

A pressure-sensitive adhesive film comprising: a filler dispersed in an acrylic polymer matrix, the filler having an average particle size smaller than a thickness of the pressure-sensitive adhesive film, wherein the filler is selected from the group consisting of : graphite, boron nitride, aluminum oxide and zinc oxide. The pressure-sensitive adhesive film of claim 1, wherein the film has a thickness of less than 15 μm, and the filler accounts for 5% by weight to 95% by weight of the film. The pressure-sensitive adhesive film of claim 1, wherein the film has a thickness of less than 10 μm, and the filler accounts for 10% by weight to 80% by weight of the film. The pressure-sensitive adhesive film of claim 1, wherein the filler is graphite, and the film has a thermal conductivity of between 1 W/mK and 3 W/mK. A heat dissipation laminate comprising: two or more heat dissipation layers, and a pressure sensitive adhesive film disposed between the heat dissipation layers; wherein the film comprises a filler dispersed in an acrylic polymer matrix, The filler has an average particle size less than the thickness of the film, and wherein the filler is selected from the group consisting of graphite, boron nitride, aluminum oxide, and zinc oxide. The heat-dissipating laminate of claim 5, wherein the film has a thickness of less than 15 μm and the filler comprises from 5% by weight to 95% by weight of the film. The heat-dissipating laminate of claim 5, wherein the film has a thickness of less than 10 μm and the filler comprises from 10% by weight to 80% by weight of the film. The heat-dissipating laminate of claim 5, wherein the filler is graphite and the film has a mediation Thermal conductivity between 1 W/mK and 3 W/mK. The heat-dissipating laminate of claim 5, wherein the heat dissipation layer is selected from the group consisting of synthetic graphite, natural graphite, aluminum, and copper foil. A heat dissipation laminate according to claim 5, wherein the heat dissipation layer comprises synthetic graphite having a thickness of between 5 μm and 25 μm. A method of preparing a pressure sensitive adhesive film comprising providing a release liner; and placing a pressure sensitive adhesive film on the release liner, wherein the film comprises a filler dispersed in an acrylic polymer matrix, the filling The agent has an average particle size less than the thickness of the film, and wherein the filler is selected from the group consisting of graphite, boron nitride, aluminum oxide, and zinc oxide. The method of claim 11, wherein the film has a thickness of less than 15 μm and the filler comprises from 5% by weight to 95% by weight of the film. An electronic article of manufacture comprising: a heat dissipating material; an electronic component; and a pressure sensitive adhesive film having a thickness disposed between the heat dissipating material and the electronic component; wherein the film comprises dispersed in an acrylic polymer matrix The filler having an average particle size smaller than the thickness of the film, wherein the filler is selected from the group consisting of graphite, boron nitride, aluminum oxide, and zinc oxide. The electronic article of claim 13, wherein the film has a thickness of less than 15 μm and the filler comprises from 5% to 95% by weight of the film. The electronic article of claim 13, wherein the film has a thickness of less than 10 μm and the filler comprises from 10% by weight to 80% by weight of the film. The electronic article of claim 13, wherein the filler is graphite and the film has a thermal conductivity of between 1 W/mK and 3 W/mK. The electronic article of claim 13, wherein the heat dissipating material is selected from the group consisting of synthetic graphite, natural graphite, aluminum, and copper foil. The electronic article of claim 13, wherein the heat dissipating material comprises synthetic graphite having a thickness of between 5 μm and 25 μm. The electronic article of claim 13, wherein the electronic component is selected from the group consisting of: a bulk microchip, a microprocessor, a transistor, a diode, a relay, a resistor, a transformer, an amplifier, and an EMI Shielding and capacitors, and wherein the electronic component has an operating temperature of between 15 ° C and 100 ° C.