Flowable curable compositions, thermally conductive compositions, and electronic heat sink assemblies containing same

Abstract

A flowable curable composition comprising 10-95 volume percent shaped composite particles dispersed in a curable binder precursor. The shaped composite particles comprise thermal filler particles having an aspect ratio of at least 1.5 held in a binder matrix. After curing, a thermally conductive composition is obtained. An electronic heat sink assembly includes an electronic component, a heat sink, and a thermally conductive composition sandwiched therebetween.

Description

[Technical Field]

[0001] The present disclosure relates generally to materials for thermal management, and more particularly to thermal management in electronic devices. [Background technology]

[0002] High through-plane thermal conductivity is required, for example, in gap fillers for automotive batteries, electrical insulation for electronic devices (including those used in fifth-generation (5G) telecommunications), motors and transformers, and dielectric heat transfer media (gap fillers) in automotive lithium battery assemblies. The need for greater efficiency and durability in electrical devices such as motors and transformers is driven by a shift toward smaller, lighter components operating at higher frequencies. Increased operating temperatures can reduce device reliability and lifetime. Many conventional electrical insulating materials have relatively low thermal conductivities, which can limit heat dissipation in electrical devices, thereby imposing constraints on device design and hindering the ability to achieve higher power density devices. Summary of the Invention

[0003] The present disclosure provides flowable curable compositions comprising shaped composite particles containing thermally conductive particles (i.e., thermal filler particles) held in a binder matrix. Advantageously, after curing, the flowable curable compositions can provide thermal cooling at lower levels of thermal filler particles than compositions in which the thermal filler is not included in the shaped composite particles. This is particularly advantageous when flake, platelet-like, or distinctly acicular thermal filler particles are used.

[0004] Thus, in one aspect, the present disclosure provides a flowable curable composition comprising 10 to 95 volume % shaped composite particles dispersed in a curable binder precursor, the shaped composite particles comprising thermal filler particles having an aspect ratio of at least 1.5 held in a binder matrix.

[0005] In a second aspect, the present disclosure provides a thermally conductive composition comprising a cured flowable curable composition according to the present disclosure.

[0006] In a third aspect, the present disclosure provides a method for manufacturing a semiconductor device comprising: Electronic components and A heat sink; a thermally conductive composition according to the present disclosure sandwiched between an electronic component and a heat sink; An electronic heat sink assembly is provided, comprising:

[0007] As used herein, The term "deformably compressible" means readily deformed (reversibly or irreversibly) upon application of pressure.

[0008] The term "hardening," as applied to a composition, refers to a process that increases the hardness of the composition, even if the composition remains relatively soft. Examples of hardening processes can include polymerization and freezing.

[0009] The term "precision molded" as applied to a composite particle means that the composite particle has an exterior surface that corresponds in shape to the mold used to make it.

[0010] The term "shaped composite particle" refers to a composite particle having a shape that corresponds at least in part to a nominal predetermined shape, which may be formed, for example, by extrusion, stencil or screen printing, or a molding process.

[0011] The features and advantages of the present disclosure will be further understood by consideration of the detailed description and appended claims. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic side view of an exemplary shaped composite particle 100 according to the present disclosure. [Figure 2] 2 is a schematic side view of an exemplary electronic heat sink assembly 200. FIG.

[0013] Repeat use of reference characters in the specification and drawings is intended to represent the same or analogous features or elements of the present disclosure. It is to be understood that those skilled in the art may devise numerous other modifications and embodiments that fall within the scope and spirit of the principles of the present disclosure. The figures may not be drawn to scale. DETAILED DESCRIPTION OF THE INVENTION

[0014] The flowable curable composition comprises 10 to 95 volume %, preferably 10 to 50 volume %, and more preferably 10 to 40 volume % of the shaped composite particles dispersed in the curable binder precursor. In some embodiments, the shaped composite particles comprise 12 to 36 volume % of the flowable curable composition.

[0015] Exemplary curable binder precursors include polymerizable resins such as epoxy resins, urethane resins, ring-opening metathesis polymerization (ROMP) cycloolefin resins, isocyanurate resins, free-radically polymerizable resins (e.g., mono- and / or multi-functional acrylates, methacrylates, acrylamides, vinyl ethers, and / or maleates), phenolic resins, urea-formaldehyde resins, aminoplast resins, silicone resins, and crosslinkable polymer latexes. Polymerizable resins typically further include a catalyst, crosslinker, and / or initiator (thermal initiator and / or photoinitiator) suitable for inducing polymerization, although this is not a requirement. The selection and amount (e.g., 0.01-10 wt.%) of catalyst, crosslinker, and / or initiator will depend on the particular chemical system selected and is within the capabilities of one skilled in the art.

[0016] Exemplary curable binder precursors also include solvent-based thermoplastic polymers, molten polymers (eg, molten hot melt adhesives), and non-crosslinked latexes (eg, acrylic latexes).

[0017] 1, an exemplary precision-molded composite particle 100 includes thermal filler particles 110 held in a binder matrix 120. The shaped composite particle 100 has a shape defined by a top 130, a bottom 140, and sides 150.

[0018] The thermal filler particles may include electrically insulating and / or electrically conductive thermally conductive particles.

[0019] Exemplary electrically insulating thermal fillers include boron nitride, aluminum nitride, silicon nitride, aluminum oxide (alumina), magnesium oxide, zinc oxide, silicon oxide, beryllium oxide, titanium oxide, copper oxide, cuprous oxide, magnesium hydroxide, aluminum hydroxide, silicon carbide, diamond, talc, mica, kaolin, bentonite, magnesite, pyrophyllite, titanium boride, calcium titanate, and combinations thereof. Boron nitride can have any structure, such as c-BN (cubic crystal structure), w-BN (wurtzite structure), h-BN (hexagonal crystal structure), r-BN (rhombohedral structure), or t-BN (turbostratic structure). Among these, aluminum oxide, aluminum hydroxide, zinc oxide, boron nitride, and aluminum nitride are generally preferred from the viewpoints of thermal conductivity and cost. Aluminum oxide and aluminum hydroxide are more preferred, and aluminum hydroxide is particularly preferred.

[0020] Exemplary conductive thermal fillers include graphite, carbon black, graphite, carbon fiber (pitch-based, PAN-based), carbon nanotubes (CNT), graphene, carbon fiber (CNF), silver, copper, iron, nickel, aluminum, titanium, their alloys, stainless steel (SUS), zinc oxide doped with different elements, ferrite, and combinations thereof. Insulating materials such as silica can be coated with an electrically conductive thermally conductive material to make them conductive, or electrically conductive thermally conductive materials can be coated with an insulating material such as silica to make them insulated, and these can be used as thermally conductive materials.

[0021] The thermal filler particles preferably have a thermal conductivity of at least 1.0 W / m·K, at least 1.2 W / m·K, at least 1.5 W / m·K, at least 1.7 W / m·K, at least 2.0 W / m·K, at least 2.5 W / m·K, at least 10 W / m·K, at least 20 W / m·K, at least 40 W / m·K, or even at least 50 W / m·K, although smaller and larger thermal conductivities may be used.

[0022] The thermal filler particles may have any shape, for example, spherical, block, needle, and / or flake / platelet shapes may be used.

[0023] The thermal filler particles can have any particle size, but preferably have a maximum dimension in the size range of 100 nanometers (nm) to 1 millimeter (mm).

[0024] The thermal filler particles may be present in the shaped composite particles in any amount, although larger amounts are typically preferred. In some embodiments, the thermal filler particles comprise 50-99% by volume of the shaped composite particles. More preferably, the thermal filler particles comprise 55-99%, 60-99%, 65-99%, 70-99%, 75-99%, 80-99%, 85-99%, or even 90-99% by volume of the shaped composite particles.

[0025] The binder matrix of the shaped composite particles can comprise any material capable of holding the thermal filler particles. It can be organic or inorganic.

[0026] The organic binder matrix may include, for example, a thermoplastic polymer and / or a thermosetting resin. Examples of suitable thermoplastic polymers include polyolefins, polyesters, thermoplastic polyurethanes, and polyamides. Examples of thermosetting resins include cured epoxy resins, cured urethane resins, cured ring-opening metathesis polymerization (ROMP) cycloolefin resins, cured isocyanurate resins, free-radical polymerized resins (e.g., polymerized mono- and / or polyfunctional acrylates, methacrylates, acrylamides, vinyl ethers, and / or maleates), cured phenolic resins, cured urea-formaldehyde resins, cured aminoplast resins, cured silicone resins, and crosslinked polymer latexes.

[0027] Details regarding general methods for forming molded (including precision molded) composite particles having an organic binder matrix can be found, for example, in U.S. Patent No. 5,714,259 (Holmes et al.). In one general method, a mixture of thermal filler particles and precursor materials for the organic binder matrix is ​​placed into mold cavities in a production tool and cured.

[0028] The shaped composite particles may further include, for example, one or more of plasticizers, pigments, stabilizers, and filler particles other than the thermal filler particles.

[0029] The inorganic binder matrix can include, for example, glass, ceramic, and glass-ceramic.

[0030] The shaped composite particles can be made by any suitable technique, including, for example, organic binder matrix molding (open or closed mold), extrusion, stencil or screen printing, or additive manufacturing, or, in the case of an inorganic matrix, spray drying or milling a mixture of inorganic binder precursor materials followed by heating (e.g., calcining and / or sintering).

[0031] Details regarding general methods for forming molded (including precision molded) composite particles having an inorganic binder matrix can be found, for example, in U.S. Patent No. 10,315,289 (B2) (Fletcher et al.). In one general method, a mixture of thermal filler particles and precursor materials for an organic binder matrix is ​​placed into mold cavities in a production tool, dried, removed from the production tool, and sintered.

[0032] The shaped composite particles can have any desired shape, including 3-, 4-, 5-, or 6-sided pyramids, 3-, 4-, 5-, or 6-sided truncated pyramids, cones, truncated cones, spheres, rods, saddles, yurt structures, and more complex shapes.

[0033] The shaped composite particles can have any particle size, but preferably have a maximum dimension in the size range of 1 micron to 5 mm, more preferably 1 micron to 0.1 mm.

[0034] Flowable curable compositions according to the present disclosure and / or cured sheets derived therefrom are useful in electronic applications, for example, as gap fillers between electronic components and heat sinks.

[0035] Exemplary curable binder precursors include polymerizable resins such as epoxy resins, urethane resins, ring-opening metathesis polymerization (ROMP) cycloolefin resins, isocyanurate resins, free-radically polymerizable resins (e.g., mono- and / or multi-functional acrylates, methacrylates, acrylamides, vinyl ethers, and / or maleates), phenolic resins, urea-formaldehyde resins, aminoplast resins, silicone resins, and crosslinkable polymer latexes. Polymerizable resins typically further include a catalyst, crosslinker, and / or initiator (thermal initiator and / or photoinitiator) suitable for inducing polymerization. The selection and amount (e.g., 0.01-10 wt.%) of catalyst, crosslinker, and / or initiator depends on the particular chemical system selected and is within the capabilities of one skilled in the art.

[0036] Exemplary curable binder precursors also include solvent-based thermoplastic polymers, molten polymers (eg, molten hot melt adhesives), and non-crosslinked latexes (eg, acrylic latexes).

[0037] 2, electronic heat sink assembly 200 includes an electronic component 210, a heat sink 230, and a thermally conductive composition 220 disposed therebetween. Thermally conductive composition 220 includes a material derived from curing a flowable hardenable composition.

[0038] Thermally conductive compositions according to the present disclosure may be provided as a cured sheet, or more typically, by applying the flowable curable composition (e.g., using a nozzle dispenser) to at least one of an electronic component or a heat sink, and then combining the flowable curable composition disposed therebetween, with subsequent curing of the flowable curable composition resulting in the thermally conductive composition.

[0039] Examples of electronic components include any electronic component that generates heat, such as, for example, integrated circuits, motors, generators, batteries, and transformers.

[0040] Heat sinks are well known in the electronics art and are often formed from a thermally conductive material (e.g., metal) that has a large thermal mass relative to the component it is intended to cool. Heat sinks often include cooling fins and / or posts.

[0041] Objects and advantages of the present disclosure are further illustrated by the following non-limiting examples, although the specific materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit the present disclosure. [Example]

[0042] Unless otherwise noted, all parts, percentages, ratios, etc. in the examples and elsewhere in this specification are by weight. Unless otherwise indicated, all other reagents were obtained or are available from fine chemical suppliers such as Sigma-Aldrich Company (St. Louis, Missouri), or can be synthesized by known methods. Table 1 (below) lists the materials used in the examples and their suppliers. [Table 1]

[0043] Test Method Thermal Conductivity Test Method Effective thermal conductivity was determined using a Thermal Interface Material (TIM) Tester (Analysis Tech, Wakefield, Massachusetts) according to ASTM D5470 Version 12. A 33 millimeter (mm) diameter sample was punched from the sliced ​​specimen and placed on the bottom plate of the TIM Tester. The pressure was set at 100 pounds per square inch (0.69 MPa).

[0044] Procedure for fabricating molded abrasive composites SAC1-SAC2 The composition (see Table 2) was mixed in a jar. Once mixed, the composition was forced against a production tool with a mold cavity (a truncated square pyramid with a base length of 0.0508 mm, a top piece length of 0.0789 mm, and a depth of 0.1000 mm) by pouring, and then a plastic spatula was used to wipe the excess from the top. The filled production tool was placed in a conventional oven set at 80°C for 1 hour. An ultrasonic horn was utilized to aid in removing the aggregates from the mold. [Table 2]

[0045] Procedure for producing comparative thermally conductive sheets CEX1 to CEX2 All ingredients except the catalyst were added to a plastic container according to Table 3 and mixed by hand using a tongue depressor. The mixture was then mixed using a Model DAC600 high-speed mixer manufactured by FlackTek (Landrum, South Carolina) at 1000 revolutions per minute (RPM) for 10 seconds, 1500 RPM for 2 minutes, and 1000 RPM for 10 seconds. The catalyst was added, followed by mixing at 1000 RPM under 100 kilopascals (kPa) for 20 seconds, followed by mixing at 1500 RPM under 4 kPa for 30 seconds.

[0046] The mixture was then transferred from the plastic container onto a release liner. A release liner was also applied over the mixture. Using a spacer (50 mils thick (1.3 millimeters)), the mixture was pressed at a pressure high enough to rely on the spacer to provide a uniform sheet thickness at room temperature (e.g., 1000 pounds per square inch (PSI) in a 6 inch x 6 inch (15 centimeters x 15 centimeter) press with a contact area of ​​3 inch x 3 inch (8 centimeters x 8 centimeters). A Model C Press (Carver, Wabash, Indiana) was used for pressing. The pressed sheet was then placed in a preheated oven set at 80°C and heated for 1 hour. [Table 3]

[0047] Procedure for making thermal conductive sheets EX1 to EX4 The shaped composite particles produced above were combined with additional ingredients in the amounts reported in Table 4 and mixed by hand in a glass jar using a tongue depressor. Mixture 36.1 was then pressed into a uniform sheet or coated between liners using a knife coater.

[0048] For pressing, the mixture was transferred from the jar to a release liner. A release liner was also applied on top of the mixture. Using a spacer (50 mils thick (1.3 mm)), the mixture was pressed at a pressure high enough to rely on the spacer to provide a uniform sheet thickness at room temperature (e.g., 1000 pounds per square inch (6.9 MPa) with a contact area of ​​3 inches by 3 inches (8 cm by 8 cm) in a 6 inch by 6 inch (15 cm by 15 cm) press). A Model C Carver Press was used for pressing. The pressed sheet was then placed in a preheated oven set at 80°C and heated for 1 hour.

[0049] For knife coating, two release liner sheets were cut to a length of 36 inches (91 cm). The knife coater was checked for the desired gap (50 mils (1.3 mm)). The sample could be deposited or poured at the knife entrance and just before the liner was pulled from the other side to obtain a sheet of material between the liners, which could then be placed in an oven set at 80°C for 1 hour. Knife coating was performed at room temperature.

[0050] In Table 4 below, Examples EX1 and EX3 were knife coated between two liners, and Examples EX2 and EX4 were pressed. [Table 4] [Table 5]

[0051] In the event of a conflict or inconsistency between any portion of an incorporated reference and this application, the information in this application shall prevail. The foregoing description is intended to enable one skilled in the art to practice the disclosure as set forth in the claims, and should not be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereof. The following are exemplary embodiments. [Item 1] 1. A flowable curable composition comprising 10 to 95 volume percent shaped composite particles dispersed in a curable binder precursor, the shaped composite particles comprising thermal filler particles having an aspect ratio of at least 1.5 held in a binder matrix. [Item 2] Item 10. The flowable curable composition of item 1, wherein the thermal filler particles comprise at least one of aluminum oxide, magnesium oxide, aluminum hydroxide, zinc oxide, hexagonal boron nitride, aluminum nitride, graphite, carbon black, or graphene. [Item 3] 3. The flowable curable composition according to item 1 or 2, wherein the thermal filler particles constitute 50 to 99 volume % of the shaped composite particles. [Item 4] 4. The flowable curable composition according to any one of items 1 to 3, wherein the curable binder precursor is polymerizable. [Item 5] 5. The flowable curable composition of any one of items 1 to 4, wherein the molded composite is precision molded. [Item 6] 6. The flowable curable composition according to any one of items 1 to 5, wherein the binder matrix is ​​organic. [Item 7] 7. The flowable curable composition of any one of items 1 to 6, wherein the thermal filler particles comprise flakes. [Item 8] 8. The flowable hardenable composition of any one of items 1 to 7, wherein the shaped composite particles are deformably compressible. [Item 9] 9. A thermally conductive composition comprising the flowable curable composition of any one of items 1 to 8 that has been cured. [Item 10] 10. The thermally conductive composition according to item 9, wherein the cured flowable curable composition has a thermal conductivity of at least 1.0 W / m·K. [Item 11] 10. The thermally conductive composition according to item 9, wherein the cured flowable curable composition has a thermal conductivity of at least 2.5 W / m·K. [Item 12] Electronic components and A heat sink; The thermally conductive composition according to any one of items 9 to 11, sandwiched between the electronic component and the heat sink; 1. An electronic heat sink assembly comprising: [Item 13] Item 13. The electronic heat sink assembly of item 12, wherein the electronic component comprises an integrated circuit. [Item 14] Item 13. The electronic heat sink assembly of item 12, wherein the electronic component comprises a motor, a generator, or a transformer.

Claims

1. 1. A flowable curable composition comprising 10 to 95 volume percent shaped composite particles dispersed in a curable binder precursor, said shaped composite particles comprising thermal filler particles having an aspect ratio of at least 1.5 held in a binder matrix, said shaped composite particles being precision shaped.

2. 10. The flowable curable composition of claim 1, wherein the thermal filler particles comprise at least one of aluminum oxide, magnesium oxide, aluminum hydroxide, zinc oxide, hexagonal boron nitride, aluminum nitride, graphite, carbon black, or graphene.

3. The flowable curable composition of claim 1 or 2, wherein said thermal filler particles comprise from 50 to 99 volume percent of said shaped composite particles.

4. The flowable curable composition of any one of claims 1 to 3, wherein the curable binder precursor is polymerizable.

5. The flowable curable composition of any one of claims 1 to 4, wherein the binder matrix is ​​organic.

6. The flowable curable composition of any one of claims 1 to 5, wherein the thermal filler particles comprise flakes.

7. A thermally conductive composition comprising the cured flowable curable composition of any one of claims 1 to 6.

8. 8. The thermally conductive composition of claim 7, wherein the cured flowable curable composition has a thermal conductivity of at least 1.0 W / m·K.

9. 8. The thermally conductive composition of claim 7, wherein the cured flowable curable composition has a thermal conductivity of at least 2.5 W / m·K.

10. Electronic components and A heat sink; The thermally conductive composition according to any one of claims 7 to 9, sandwiched between the electronic component and the heat sink; 1. An electronic heat sink assembly comprising:

11. The electronic heat sink assembly of claim 10 , wherein the electronic component comprises an integrated circuit.

12. The electronic heat sink assembly of claim 10 , wherein the electronic component comprises a motor, a generator, or a transformer.

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