High thermal conductivity hybrid thermal interface material

Abstract

The invention discloses a thermal interface material. The thermal interface material at least comprises a diamond-containing filler; silicone oil, and a plurality of additives; and a method for applying a thermal interface material to a substrate, the method comprising: combining a thermally conductive filler, a silicone oil, and each of a plurality of additives to form the thermal interface material; wherein the thermally conductive filler comprises a blended diamond filler; and applying the thermal interface material to a metal substrate.

Description

Cross-references to related applications

[0001] This application claims priority to U.S. Patent Application No. 18 / 741,727, filed June 12, 2024, entitled "Highly Thermally Conducive Hybrid Thermal Interface Material," which is pursuant to 35 USC. 119(e) claims priority to U.S. Provisional Application No. 63 / 524,404, filed June 30, 2023, entitled “Highly Thermally Conductive Hybrid Thermal Interface Material,” both of which are incorporated herein by reference in their entirety. Technical Field

[0002] This disclosure relates generally to thermal interface materials, and more specifically to thermal interface materials with high thermal conductivity. Background Technology

[0003] Thermal interface materials (TIMs) are widely used to dissipate heat from electronic components such as central processing units, video graphics arrays, servers, game consoles, smartphones, and LED boards. TIMs are typically used to transfer excess heat from electronic components to heat sinks, such as heat exchangers.

[0004] Thermally conductive thermally conductive materials (TIMs) are traditionally gel-like thermally conductive materials made from silicone composites and thermally conductive fillers. These TIMs exhibit low thermal resistance, can form / shape on heat dissipation components and automatically fill gaps, provide insulation, maximize limited contact area, and are infinitely compressible.

[0005] As integrated circuits become increasingly prevalent, circuit sizes are shrinking, and the amount of heat generated is increasing. To dissipate this significant heat, thermally conductive materials with high thermal conductivity are needed. However, thermal pads with high thermal conductivity can be quite thick and incompressible. Due to their thickness, they may not be able to accommodate smaller circuits. Most known thermally conductive TIMs, while compressible to accommodate small circuits, have relatively low thermal conductivity. Therefore, TIM compositions with increased thermal conductivity are needed. Summary of the Invention

[0006] This disclosure provides compositions for use in thermal interface materials, the thermal interface materials comprising diamond-containing fillers, silicone oil, and various additives.

[0007] This disclosure also provides a method for applying a thermal interface material to a substrate. The method includes combining each of a thermally conductive filler, a silicone oil, and a plurality of additives to form a thermal interface material, and applying the thermal interface material to a metal substrate, the thermally conductive filler comprising a blended diamond filler.

[0008] This disclosure further provides an electronic component including a heat sink, an electronic chip, and a thermal interface material located between the heat sink and the electronic chip. The thermal interface material includes a thermally conductive filler comprising a blend of diamond filler, silicone oil, and various additives. Attached Figure Description

[0009] The above and other features and advantages of this disclosure, as well as the ways in which they are realized, will become more apparent and the invention itself will be better understood by referring to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0010] Figure 1A The electronic chip, heat sink, heat fins, and first and second thermal interface materials are schematically shown.

[0011] Figure 1B An exemplary thermal interface material positioned between an electronic chip and a heat sink is schematically shown;

[0012] Figure 1C An exemplary thermal interface material positioned between a radiator and a heat sink is schematically shown;

[0013] Figure 1D An exemplary thermal interface material positioned between an electronic chip and a heat sink is schematically shown;

[0014] Figure 2A The vertical stability of comparative composition 1 is shown;

[0015] Figure 2B The vertical stability of composition 1 of the present invention is shown; and

[0016] Figure 2C The vertical stability of composition 2 of the present invention is shown.

[0017] In several views, the corresponding index characters indicate the corresponding parts. The examples presented herein illustrate exemplary embodiments of the invention, and such examples should not be construed as limiting the scope of the invention in any way. Detailed Implementation

[0018] This invention relates to thermal interface materials that can be used to transfer heat away from electronic components. Specifically, this invention relates to high thermal conductivity thermal interface materials comprising a relatively high weight percentage of diamond filler, which can be used to transfer heat away from electronic components.

[0019] I. Thermal interface material composition :

[0020] This invention relates to thermal interface materials (TIMs) that can be used to transfer heat away from electronic components, exhibiting higher thermal conductivity compared to conventional TIMs. The thermal interface material compositions disclosed herein may include diamond-containing fillers, silicone oils, and various additives. The thermal interface materials may be surfactant-free and emulsifier-free. In some exemplary embodiments, the TIM is prepared by combining the individual components in a heated mixer and blending the composition together. The blended composition can then be applied directly to a substrate, such as in a stencil printing process.

[0021] A. Diamond-containing fillers

[0022] Thermal interface material compositions may include diamond-containing fillers. Diamond-containing fillers can increase the thermal conductivity of thermal interface materials while reducing any sedimentation during the formation of TIM compositions.

[0023] Exemplary diamond-containing fillers may include any or a combination of the following: diamond, metal oxides, and / or ceramics. Metal oxides or ceramics may include, but are not limited to, alumina (aluminum oxide), aluminum nitride, boron nitride, zinc oxide, and tin oxide.

[0024] One component of the diamond-containing filler may be zinc oxide. The D50 particle size of the zinc oxide may be 0.45 μm, 0.50 μm to 0.55 μm, 0.60 μm, 0.65 μm, or any range using any two of the foregoing values ​​as endpoints, such as 0.45 μm to 0.65 μm, or 0.50 μm to 0.60 μm, as measured by a Mastersizer 3000 laser particle size analyzer. The diamond-containing filler may include zinc oxide in the following weight percentages: for example, 0.2 wt%, 0.5 wt%, 1.0 wt% to 1.5 wt%, 2.0 wt%, 2.5 wt%, or any range using any two of the foregoing values ​​as endpoints, such as 0.2 wt% to 2.5 wt%, 0.5 wt% to 2.0 wt%, or 1.0 wt% to 1.5 wt%, where the weight percentage is based on the total weight of the diamond-containing filler.

[0025] One component of the diamond-containing filler may be alumina (D50 of 2 μm to 5 μm). The D50 particle size of the alumina may be 2 μm, 3 μm to 4 μm, 5 μm, or any range using any two of the foregoing values ​​as endpoints, such as 2 μm to 5 μm, or 3 μm to 4 μm, as measured by a Mastersizer 3000 laser particle size analyzer. The diamond-containing filler may include zinc oxide (D50 of 2 μm to 5 μm) in the following weight percentages: for example, 5 wt%, 10 wt%, 15 wt% to 20 wt%, 25 wt%, 30 wt%, or any range using any two of the foregoing values ​​as endpoints, such as 5 wt% to 30 wt%, 10 wt% to 25 wt%, or 15 wt% to 20 wt%, where the weight percentage is based on the total weight of the diamond-containing filler.

[0026] One component of the diamond-containing filler may be alumina (D50 of 10 μm to 15 μm). The D50 particle size of the alumina may be 10 μm, 12 μm to 14 μm, 15 μm, or any range using any two of the foregoing as endpoints, such as 10 μm to 15 μm or 12 μm to 14 μm, as measured by a Mastersizer 3000 laser particle size analyzer. The diamond-containing filler may include zinc oxide (D50 of 10 μm to 15 μm) in the following weight percentages: for example, 5 wt%, 7 wt%, 9 wt% to 11 wt%, 13 wt%, 15 wt%, or any range using any two of the foregoing values ​​as endpoints, such as 5 wt% to 15 wt%, 7 wt% to 13 wt%, or 9 wt% to 11 wt%, where the weight percentage is based on the total weight of the diamond-containing filler.

[0027] One component of the diamond-containing filler may be alumina (D50 of 25 μm to 45 μm). The D50 particle size of the alumina may be 25 μm, 30 μm to 35 μm, 45 μm, or any range using any two of the foregoing values ​​as endpoints, such as 25 μm to 45 μm, or 30 μm to 35 μm, as measured by a Mastersizer 3000 laser particle size analyzer. The diamond-containing filler may include zinc oxide (D50 of 25 μm to 45 μm) in the following weight percentages: for example, 30 wt%, 40 wt%, 45 wt% to 50 wt%, 60 wt%, 65 wt%, or any range using any two of the foregoing values ​​as endpoints, such as 30 wt% to 65 wt%, 40 wt% to 60 wt%, or 45 wt% to 50 wt%, where the weight percentage is based on the total weight of the diamond-containing filler.

[0028] One component of the diamond-containing filler may be aluminum nitride. The D50 particle size of the aluminum nitride may be 80 μm, 90 μm to 100 μm, 120 μm, or any range using any two of the foregoing values ​​as endpoints, such as 80 μm to 120 μm or 90 μm to 100 μm, as measured by a Mastersizer 3000 laser particle size analyzer. The diamond-containing filler may include aluminum nitride in the following weight percentages: for example, 40 wt%, 45 wt%, 50 wt% to 55 wt%, 60 wt%, 65 wt%, or any range using any two of the foregoing values ​​as endpoints, such as 40 wt% to 65 wt%, 45 wt% to 60 wt%, or 50 wt% to 55 wt%, based on the total weight of the diamond-containing filler.

[0029] One component of a diamond-containing filler may be diamond (D50 of 80 μm to 100 μm). The D50 particle size of the diamond may be 80 μm, 85 μm to 90 μm, 100 μm, or any range using any two of the foregoing values ​​as endpoints, such as 80 μm to 100 μm, or 85 μm to 90 μm, as measured by a Mastersizer 3000 laser particle size analyzer. Diamond-containing fillers may include diamond (D50 of 80 μm to 100 μm) in the following weight percentages: for example, 2 wt%, 4 wt%, 5 wt% to 6 wt%, 8 wt%, 10 wt%, or any range using any two of the foregoing values ​​as endpoints, such as 2 wt% to 10 wt%, 4 wt% to 8 wt%, or 5 wt% to 6 wt%, based on the total weight of the diamond-containing filler.

[0030] One component of a diamond-containing filler may be diamond (D50 of 110 μm to 130 μm). The D50 particle size of the diamond may be 110 μm, 115 μm to 120 μm, 130 μm, or any range using any two of the aforementioned values ​​as endpoints, such as 110 μm to 130 μm, or 115 μm to 120 μm, as measured by a Mastersizer 3000 laser particle size analyzer. Diamond-containing fillers may include diamond (D50 of 110 μm to 130 μm) in the following weight percentages: for example, 5 wt%, 7 wt%, 9 wt% to 11 wt%, 13 wt%, 15 wt%, or any range using any two of the aforementioned values ​​as endpoints, such as 5 wt% to 15 wt%, 7 wt% to 13 wt%, or 9 wt% to 11 wt%, based on the total weight of the diamond-containing filler.

[0031] The thermal interface material compositions provided in this disclosure may include diamond-containing fillers in weight percentages of, for example, 90 wt%, 92 wt%, 94 wt% to 96 wt%, 97 wt%, or 98 wt%, or any range using any two of the foregoing values ​​as endpoints, wherein the weight percentages are based on the total weight of the TIM composition. For example, thermally conductive fillers may comprise 90 wt% to 98 wt%, 92 wt% to 97 wt%, or 94 wt% to 96 wt%.

[0032] Thermally conductive fillers can be selected based on average particle size. For example, a smaller particle size can be selected based on a desired higher filler density, resulting in higher coating performance of the TIM composition. In this case, the thermally conductive filler can have the following average particle sizes: as low as 0.1 micrometers, 1 micrometer, 10 micrometers, up to 50 micrometers, 75 micrometers, or 100 micrometers, or any range defined between any two of the foregoing values.

[0033] B. Silicone oil

[0034] This invention provides a matrix for a thermally conductive ink (TIM) material comprising at least one long-chain silicone oil. The silicone oil may contain one or more crosslinkable groups, such as vinyl and hydride functional groups, crosslinked by a catalyst. The silicone oil may comprise long-chain alkyl silicone oil, vinyl-terminated alkyl silicone oil, and single-terminated hydroxyl silicone oil. The silicone oil wets thermally conductive fillers and forms a distributable fluid for the TIM.

[0035] As described herein, "long-chain" silicone oils include at least one branch or alkyl branch that extends from the main chain and varies in carbon number. Alkyl branches have the general formula:

[0036]

[0037] Where x is an integer greater than 1. In some embodiments, x is as low as 2, 4, 6, 8, 10, 12, and as high as 16, 18, 20, 24, 28, 32, or any range defined between any two of the foregoing values, such as between 2 and 32, between 6 and 16, and between 4 and 12. Compared to silicone oils with the same molecular weight but without alkyl branches, branched silicone oils can achieve lower viscosity and less molecular chain entanglement. Lower viscosity facilitates the formulation of thermally conductive fillers with high loading capacity in thermal interface materials, especially for high molecular weight silicone oils (i.e., higher molecular weight means longer Si-O-Si chains and greater molecular chain entanglement).

[0038] In one exemplary embodiment, the silicone oil includes silicone rubber, such as the KE series products purchased from Shin-Etsu Corporation, or SILBIONE purchased from Bluestar Corporation. ®Such as ELASTOSIL purchased from Wacker ® SilGel ® SILPURAN ® and SEMICOSIL ® Such as the Silopren purchased from Momentive. ® Such as Dow Corning, which was purchased from Dow Corning. ® Silastic ® XIAMETER ® Syl-Off ® and SYLGARD ® Such as SQUARE, acquired from Square Silicone. ® Such as Andril, purchased from AB specialty Silicones ® Other polysiloxanes were purchased from Wacker Chemie, Shin-Etsu Chemical, Dow Corning, Momentive, Bluestar, Runhe, Ambia Specialty Silicones, Gelest, and United Chemical Technologies.

[0039] The thermal interface material composition provided in this disclosure may include silicone oil in the following total weight percentages: for example, 1 wt%, 2.5 wt%, 3 wt%, 4 wt%, 4.5 wt%, or 5 wt%, or any range using any two of the foregoing values ​​as endpoints, wherein the weight percentage is based on the total weight of the thermal interface material composition. For example, the thermal interface material may comprise 1 wt% to 5 wt%, 2.5 wt% to 4.5 wt%, or 3 wt% to 4 wt%. In one embodiment, the thermal interface material may comprise 2.5 wt% to 4.5 wt%.

[0040] i. Long-chain alkyl silicone oil

[0041] TIM may contain long-chain alkyl silicone oils. Long-chain alkyl silicone oils provide lubrication between molecular chains and reduce entanglement of molecular chains in the formulation. An exemplary long-chain alkyl silicone oil may be a dimethyl silicone oil in which some methyl groups are replaced by long-chain alkyl groups. An exemplary long-chain alkyl silicone oil may have the following general formula:

[0042]

[0043] In the general formula shown above, n can be as low as 0, 10, 50, 100, 500, or as high as 1000, 2000, 5000, 10000, or any range defined between any two of the aforementioned values; x can be as low as 2, 4, 6, 8, 10, 12, or as high as 16, 18, 20, 24, 28, 32, or any range defined between any two of the aforementioned values, such as between 2 and 32, between 6 and 16, and between 4 and 12; and m can be in the range of 5, 10, 50, 200, or as high as 500, 1000, 2000, 5000, or any range defined between any two of the aforementioned values. Furthermore, n+m is in the range of 10, 30, 50, 100, 200, 500, or 1000, 2000, 5000, 10000, 15000, or any range defined between any two of the aforementioned values, such as between 10 and 15000, between 1000 and 5000, and between 500 and 2000. In one exemplary embodiment, x is in the range of 4 and 16. In another exemplary embodiment, x is in the range of 5 and 15. In another exemplary embodiment, x is in the range of 7 and 11. In one exemplary embodiment, n is in the range of 50 and 100. In another exemplary embodiment, n is in the range of 100 and 500. In another exemplary embodiment, n is in the range of 500 and 1000. In one exemplary embodiment, m is in the range of 10 and 100. In another exemplary embodiment, m is in the range of 100 and 500. In one exemplary embodiment, n+m is in the range between 50 and 200. In another exemplary embodiment, n+m is in the range between 200 and 1000.

[0044] Exemplary long-chain alkyl silicone oils may include: polydimethyl silicone oil, BALD-BD1206 (viscosity 500 cst) purchased from Baoerde, RH-8206 (viscosity 900 cst to 1500 cst) and RH-8207A (viscosity 1000 cst to 1500 cst) each purchased from Runhe Company, YD-8206 (viscosity 300 cst to 2500 cst) purchased from Ailidi, OFX0203 (viscosity 1000 cst to 1500 cst) purchased from Dow Corning, and BS-220 (viscosity 5000 cst) purchased from Blue Silane.

[0045] The weight-average molecular weight (Mw) of exemplary long-chain alkyl silicone oils can be as low as 1,000 Daltons, 9,000 Daltons, or 20,000 Daltons, or as high as 30,000 Daltons, 100,000 Daltons, or 200,000 Daltons, or any range defined between any two of the foregoing values, as determined by gel permeation chromatography (GPC).

[0046] As measured according to ASTM D445, the kinematic viscosity of an exemplary long-chain alkyl silicone oil may be 10 cSt, 50 cSt, 100 cSt to 200 cSt, 500 cSt, 1000 cSt, or any range defined between any two of the foregoing values, such as 10 cSt to 1000 cSt, 50 cSt to 500 cSt, or 100 cSt to 200 cSt. In one exemplary embodiment, the kinematic viscosity of the exemplary long-chain alkyl silicone oil is between 50 cSt and 200 cSt.

[0047] The thermal interface material composition may include one or more long-chain alkyl silicone oils in amounts of 0.5 wt%, 1 wt%, 1.5 wt% to 2 wt%, 2.5 wt%, 3 wt%, or any range using any two of the foregoing values ​​as endpoints, wherein the wt% is based on the total weight of the thermal interface material composition, such as 0.5 wt% to 3 wt%, 1 wt% to 2.5 wt%, or 2 wt% to 2.5 wt%.

[0048] ii. Long-chain vinyl-terminated alkyl silicone oils

[0049] Another exemplary long-chain silicone oil for TIM may include a long-chain vinyl-terminated alkyl silicone oil. The long-chain vinyl-terminated alkyl silicone oil can form a crosslinked matrix with a crosslinking agent through its terminal vinyl functional groups. An exemplary long-chain vinyl-terminated alkyl silicone oil may have the following general formula:

[0050]

[0051] In the general formula shown above, n can be as low as 0, 10, 50, 100, 200, 500, or as high as 1000, 2000, 5000, 10000, or any range defined between any two of the aforementioned values; x can be as low as 2, 4, 6, 8, 10, 12, or as high as 16, 18, 20, 24, 28, 32, or any range defined between any two of the aforementioned values, such as between 2 and 32, between 6 and 16, and between 4 and 12; and m can be in the range of 5, 10, 50, 200, or as high as 500, 1000, 2000, 5000, or any range defined between any two of the aforementioned values. Furthermore, n+m is in the range of 10, 30, 50, 100, 200, 500, or 1000, 2000, 5000, 10000, 15000, 20000, or any range defined between any two of the aforementioned values, such as between 10 and 20000, between 1000 and 5000, and between 500 and 2000. In one exemplary embodiment, x is in the range of 4 and 16. In another exemplary embodiment, x is in the range of 5 and 15. In another exemplary embodiment, x is in the range of 7 and 11. In one exemplary embodiment, n is in the range of 200 and 500. In another exemplary embodiment, n is in the range of 1000 and 3000. In another exemplary embodiment, n is in the range of 2000 and 5000. In one exemplary embodiment, m is in the range of 150 and 300. In another exemplary embodiment, m is in the range of 300 and 500. In another exemplary embodiment, m is in the range of 500 to 1500. In one exemplary embodiment, n+m is in the range of 200 to 1000. In another exemplary embodiment, n+m is in the range of 1000 to 5000. In yet another exemplary embodiment, n is in the range of 50 to 200.

[0052] Vinyl functional silicone oils comprise organosilicon components having Si-CH═CH2 groups. Exemplary vinyl functional silicone oils may include vinyl-terminated silicone oils, vinyl-grafted silicone oils in which Si-CH═CH2 groups are grafted onto polymer chains, and combinations thereof.

[0053] Exemplary vinyl-terminated silicone oils may include vinyl-terminated polydimethylsiloxanes, such as DMS-V00 (weight-average molecular weight (Mw) of 186 Daltons), DMS-V03 (Mw of about 500 Daltons), DMS-V05 (Mw of about 800 Daltons), DMS-V21 (Mw of about 6,000 Daltons), DMS-V22 (Mw of about 9,400 Daltons), DMS-V25 (Mw of about 17,200 Daltons), DMS-V25R (Mw of about 17,200 Daltons), DMS-V35 (Mw of about 49,500 Daltons), and DMS-V35R (Mw of about 49,500 Daltons), each purchased from Geles, Inc. Exemplary vinyl-terminated silicone oils may include vinyl-terminated diphenylsiloxane-dimethylsiloxane copolymers, such as PDV-0325 (Mw of about 15,500 Daltons), PDV-0331 (Mw of about 27,000 Daltons), PDV-0525 (Mw of about 14,000 Daltons), PDV-1625 (Mw of about 9,500 Daltons), PDV-1631 (Mw of about 19,000 Daltons), and PDV-2331 (Mw of about 12,500 Daltons), each purchased from Gales Corporation. Exemplary vinyl-terminated silicone oils may include vinyl-terminated polyphenylmethylsiloxanes, such as PMV-9925 (Mw of about 2,000 to 3,000 Daltons), purchased from Gales Corporation. Exemplary vinyl-terminated silicone oils may include vinyl-terminated diethylsiloxane-dimethylsiloxane copolymers, such as EDV-2025 (Mw of about 16,500 to 19,000 Daltons) purchased from Gales.

[0054] Exemplary vinyl-terminated silicone oils may include vinyl-terminated polydimethylsiloxanes, such as DMS-V41 (Mw of about 62,700 Daltons), DMS-V42 (Mw of about 72,000 Daltons), DMS-V46 (Mw of about 117,000 Daltons), DMS-V51 (Mw of about 140,000 Daltons), and DMS-V52 (Mw of about 155,000 Daltons), each purchased from Gales Corporation.

[0055] Exemplary vinyl-grafted silicone oils may include vinylmethylsiloxane homopolymers, such as VMS-005 (Mw of about 258 Daltons to 431 Daltons) and VMS-T11 (Mw of about 1000 Daltons to 1500 Daltons), both purchased from Gales. Exemplary vinyl-grafted silicone oils include vinylmethylsiloxane-dimethylsiloxane copolymers, such as trimethylsiloxy-terminated silicone oils, silanol-terminated silicone oils, and vinyl-terminated silicone oils.

[0056] Exemplary vinyl-grafted silicone oils may include vinylmethylsiloxane terpolymers, such as vinylmethylsiloxane-octylmethylsiloxane-dimethylsiloxane terpolymers, and vinylmethylsiloxane-dimethylsiloxane copolymers, such as trimethylsiloxy-terminated silicone oils, silanol-terminated silicone oils, and vinyl-terminated silicone oils.

[0057] In one exemplary embodiment, the vinyl-grafted silicone oil is a vinylmethylsiloxane terpolymer. In one exemplary embodiment, the vinyl-functionalized silicone oil includes vinyl T resin or vinyl Q resin.

[0058] In one exemplary embodiment, the silicone oil is a vinyl-functionalized oil, such as RH-Vi303 or RH-Vi301 purchased from Runhe Company, or Andril purchased from Ambia Specialty Silicones Company. ® VS 200, Andril ® VS 1000.

[0059] The weight-average molecular weight (Mw) of exemplary long-chain vinyl-terminated alkyl silicone oils can be as low as 1,000 Daltons, 9,000 Daltons, or 20,000 Daltons, or as high as 30,000 Daltons, 100,000 Daltons, or 200,000 Daltons, or any range defined between any two of the foregoing values, as determined by gel permeation chromatography (GPC).

[0060] As measured according to ASTM D445, the kinematic viscosity of the exemplary long-chain vinyl-terminated alkyl silicone oil may be 10 cSt, 50 cSt, 100 cSt to 200 cSt, 400 cSt, 500 cSt, or any range defined between any two of the foregoing values, such as 10 cSt to 500 cSt, 50 cSt to 400 cSt, or 100 cSt to 200 cSt. In one exemplary embodiment, the kinematic viscosity of the exemplary long-chain vinyl-terminated alkyl silicone oil is between 50 cSt and 200 cSt.

[0061] The thermal interface material composition may include one or more long-chain vinyl-terminated alkyl silicone oils in the following amounts: 0.25 wt%, 0.5 wt%, 1 wt% to 1.5 wt%, 2 wt%, 2.5 wt%, or any range using any two of the foregoing values ​​as endpoints, wherein the wt% is based on the total weight of the thermal interface material composition, such as 0.25 wt% to 2.5 wt%, 0.5 wt% to 2 wt%, or 1 wt% to 1.5 wt%.

[0062] C. Dispersant

[0063] Thermal interface materials may also include dispersants. Dispersants provide wettability to the thermally conductive fillers and prevent potential evaporation of the silicone oil during formulation curing or other processing. Dispersants also reduce friction between thermally conductive fillers.

[0064] The dispersant can be a long-chain, single-hydroxyl-terminated silicone oil. An exemplary long-chain, single-hydroxyl-terminated silicone oil dispersant may have the following general formula:

[0065]

[0066] In the general formula shown above, n can be as low as 5, 10, 50, 100, 500, or as high as 1000, 2000, 5000, 10000, or any range defined between any two of the aforementioned values; x can be as low as 2, 4, 6, 8, 10, 12, or as high as 16, 18, 20, 24, 28, 32, or any range defined between any two of the aforementioned values, such as between 2 and 32, between 6 and 16, and between 4 and 12; and m can be in the range of 0, 5, 10, 50, 100, 200, or as high as 500, 1000, 2000, 5000, or any range defined between any two of the aforementioned values, such as between 5 and 5000, between 5 and 50, and between 50 and 500. Furthermore, n+m is in the range of 10, 30, 50, 100, 200, 500, or 1000, 2000, 5000, 10000, 15000, or any range defined between any two of the aforementioned values, such as between 10 and 10000, between 1000 and 5000, and between 500 and 2000. In one exemplary embodiment, x is in the range of 4 and 16. In another exemplary embodiment, x is in the range of 5 and 15. In another exemplary embodiment, x is in the range of 7 and 11. In one exemplary embodiment, n is in the range of 10 and 100. In another exemplary embodiment, n is in the range of 100 and 500. In another exemplary embodiment, n is in the range of 500 and 2000. In another exemplary embodiment, n is in the range of 2000 and 5000. In another exemplary embodiment, n is in the range of 5000 and 10000. In one exemplary embodiment, m is 0. In another exemplary embodiment, m is in the range of 1 to 20. In another exemplary embodiment, m is in the range of 10 to 100. In another exemplary embodiment, m is in the range of 50 to 500, y is in the range of 1 to 3, and R is a hydrocarbon group. When the molecular weight of the single-hydroxyl-terminated silicone oil is not higher than 10,000 Daltons, or the loading of the single-hydroxyl-terminated silicone oil into the final thermal interface material is not higher than 2% by weight, m ​​may be 0. In one exemplary embodiment, m+n is in the range of 10 to 100. In another exemplary embodiment, m+n is in the range of 100 to 500. In another exemplary embodiment, m+n is in the range of 500 to 2000. In another exemplary embodiment, m+n is in the range of 2000 to 5000. In another exemplary embodiment, m+n is in the range of 5000 to 10000.

[0067] The hydroxyl value is a measure of the amount of free hydroxyl groups in a chemical substance, usually expressed in milligrams (mg) of potassium hydroxide (KOH), equivalent to the hydroxyl content of one gram of the substance. In general analytical methods, the hydroxyl value (mgKOH / g) is defined as the mass (in milligrams) of potassium hydroxide required to neutralize acetic acid, which is absorbed when one gram of long-chain, single-ended hydroxyl-capped silicone oil is acetylated. Traditional analytical methods for determining the hydroxyl value involve acetylating the free hydroxyl groups of the substance with acetic anhydride in a pyridine solvent. After the reaction is complete, water is added, and the remaining unreacted acetic anhydride is converted into acetic acid and measured by titration with potassium hydroxide. The hydroxyl value can be calculated using the following formula.

[0068]

[0069] Where HV is the hydroxyl value; V B The volume (mL) of potassium hydroxide solution required for a blank titration; V acet The volume (mL) of potassium hydroxide solution required for titrating the acetylated sample; W acet , where is the weight (in grams) of the sample used for acetylation; N is the equivalent concentration of the titrant; 56.1 is the molecular weight of potassium hydroxide.

[0070] The hydroxyl values ​​of exemplary long-chain, single-hydroxyl-terminated silicone oils can be as low as 0.001 mg KOH / g, 0.01 mg KOH / g, 0.1 mg KOH / g, 1 mg KOH / g, 5 mg KOH / g, and as high as 10 mg KOH / g, 20 mg KOH / g, 50 mg KOH / g, 100 mg KOH / g, or any range defined between any two of the foregoing values, such as 0.01 mg KOH / g to 100 mg KOH / g, 1 mg KOH / g to 5 mg KOH / g, 1 mg KOH / g to 50 mg KOH / g, as determined by a general KOH (potassium hydroxide) titration method. In one exemplary embodiment, the hydroxyl value of the exemplary long-chain, single-hydroxyl-terminated silicone oil is in the range of 5 mg KOH / g to 35 mg KOH / g.

[0071] The weight-average molecular weight (Mw) of an exemplary long-chain, single-ended hydroxyl-terminated silicone oil may be 500 Daltons, 1000 Daltons, 2000 Daltons to 3000 Daltons, 4000 Daltons, 5000 Daltons, or any range defined between any two of the foregoing values, such as 500 Daltons to 5000 Daltons, 1000 Daltons to 4000 Daltons, or 2000 Daltons to 3000 Daltons, as determined by gel permeation chromatography (GPC).

[0072] The kinematic viscosity of an exemplary long-chain, single-ended hydroxyl-terminated silicone oil may be 10 cSt, 50 cSt, 100 cSt to 200 cSt, 400 cSt, 500 cSt, or any range defined between any two of the foregoing values, such as 10 cSt to 500 cSt, 50 cSt to 400 cSt, or 100 cSt to 200 cSt, as measured according to ASTM D445.

[0073] The thermal interface material composition may include one or more long-chain, single-ended hydroxyl-terminated silicone oils in amounts of 0.5 wt%, 1 wt%, 1.25 wt% to 1.5 wt%, 1.75 wt%, 2 wt%, or any range using any two of the foregoing values ​​as endpoints, wherein the wt% is based on the total weight of the thermal interface material composition, such as 0.5 wt% to 2 wt%, 1 wt% to 1.75 wt%, or 1.25 wt% to 1.5 wt%. In one exemplary embodiment, the thermal interface material includes 0.5 wt% to 1 wt% of a long-chain, single-ended hydroxyl-terminated silicone oil dispersant.

[0074] D. Crosslinking agent

[0075] In an exemplary embodiment, the TIM may include a crosslinking agent to enable crosslinking between silicone oils. The crosslinking agent may include crosslinked silicone oils.

[0076] Crosslinked silicone oils may contain Si-H groups. Exemplary silicone oils may contain hydrogen-containing silicone oils having the general formula shown below. Exemplary hydrogen-containing silicone oils act as crosslinking agents in addition reactions with primary silicone oils.

[0077]

[0078] Crosslinked silicone oils may include hydrogen-containing silicone oils on one or both sides and end-side hydrogen-containing silicone oils. Exemplary silicone oils may include hydrogen-containing silicone oils having the general formula shown below: Exemplary hydrogen-containing silicone oils are used as crosslinking agents in addition reactions with the primary silicone oil.

[0079] General formula for hydrogen-containing silicone oil on both sides:

[0080]

[0081] End-side hydrogen-containing general formula:

[0082]

[0083] The molar ratio of Si-H groups in crosslinked silicone oil can be determined by iodometric titration. The iodometric titration involves: weighing approximately 0.1 g of hydrogenated silicone oil into a foil-wrapped conical flask. Add 20 mL of carbon tetrachloride (CCl4) to the flask to dissolve the silicone oil, and then further seal the flask to avoid exposure. Next, add excess bromoacetic acid solution (approximately 10 mL available) along with 10 mL of water to the flask. Seal the flask again to avoid exposure. After 30 minutes, open the seal and add 25 mL of a 10% (w / w) potassium iodide (KI) aqueous solution to the solution. Shake the solution for 1 to 2 minutes. Then add a standard 0.1 mol / L sodium thiosulfate (Na₂S₂O₃) aqueous solution, titrating the sample solution while shaking. Add 1 mL of a 1% (w / w) starch aqueous solution to the solution as an indicator. When the color of the solution changes (e.g., blue), stop the titration and calculate the amount of sodium thiosulfate consumed. Repeat this process for other samples. To prepare a control sample, repeat the process without using silicone oil. The content (mmol / g) of Si-H groups is as follows:

[0084]

[0085] Where: N2 is the molar ratio of Si-H groups (mmol / g); V d The volume (ml) of sodium thiosulfate solution titrated with the hydrogenated silicone oil sample; V c G1 is the volume (ml) of sodium thiosulfate solution titrated with the blank sample; G2 is the weight (g) of the hydrogenated silicone oil; M2 is the molar concentration (mol / l) of the standard sodium thiosulfate solution.

[0086] The molar ratio (mmol / g) of Si-H groups in the silicone oil can be 0.01 mmol / g, 0.05 mmol / g, 0.10 mmol / g to 0.15 mmol / g, 0.20 mmol / g, 0.35 mmol / g, or any range defined between any two of the foregoing values, such as 0.05 mmol / g to 0.35 mmol / g, 0.10 mmol / g to 0.20 mmol / g, or 0.15 mmol / g to 0.20 mmol / g. In one exemplary embodiment, the amount of the molar ratio of Si-H groups is 0.05 mmol / g to 0.15 mmol / g.

[0087] The kinematic viscosity of an exemplary crosslinked silicone oil can be 0.5 mm. 2 / s, 1mm 2 / s, 10mm 2 / s to 100mm 2 / s, 250mm 2 / s, 500mm 2 / s, or any range defined between any two of the aforementioned values, such as 0.5mm 2 / s to 500mm 2 / s, 1mm 2 / s to 250mm 2 / s, or 10mm 2 / s to 100mm 2 / s, as measured according to ASTM D445. In one exemplary embodiment, the kinematic viscosity of the crosslinked silicone oil is 100 mm. 2 / s and 200mm 2 Between / s.

[0088] In some exemplary embodiments, based on the total weight of the thermal interface material, the TIM includes one or more crosslinking agents in amounts of: 0.05 wt%, 0.10 wt%, 0.15 wt% to 0.20 wt%, 0.25 wt%, 0.30 wt%, or any range defined between any two of the foregoing values, such as 0.05 wt% to 0.30 wt%, 0.10 wt% to 0.25 wt%, or 0.15 wt% to 0.20 wt%. In one exemplary embodiment, the TIM includes 0.20 wt% to 0.30 wt% of crosslinking agent.

[0089] Total Si-H group content (T) Si—H (mmol) and total vinyl content (T) 乙烯基 The ratio of () can be calculated using the following formula:

[0090]

[0091] TIM may include a ratio of Si-H group content to total vinyl content of 0.01, 0.1, 0.5 to 1.0, 1.5, 2.0, or any range defined between any two of the foregoing values, such as 0.01 to 2.0, 0.1 to 1.5, or 0.5 to 1.0. In one exemplary embodiment, the ratio of Si-H group content to total vinyl content is 0.1 to 1.0. In another exemplary embodiment, the ratio of Si-H group content to total vinyl content is 0.1 to 0.5.

[0092] E. Catalyst

[0093] The TIM may further comprise one or more catalysts for catalytic addition reactions. Exemplary catalysts include platinum-containing materials and rhodium-containing materials.

[0094] Exemplary catalysts may include platinum-containing materials and rhodium-containing materials. An exemplary platinum-containing catalyst may have the following general formula:

[0095]

[0096] Exemplary platinum-containing catalysts may include: platinum cyclovinylmethylsiloxane complexes (Ashby Karstedt catalyst), platinum carbonyl cyclovinylmethylsiloxane complexes (Ossko catalyst), divinyltetramethyldisiloxane-dimethylfumarate platinum complexes, divinyltetramethyldisiloxane-dimethylmaleate platinum complexes, etc. Exemplary platinum carbonyl cyclovinylmethylsiloxane complexes may include SIP6829.2, exemplary platinum divinyltetramethyldisiloxane complexes may include SIP6830.3 and SIP6831.2, and exemplary platinum cyclovinylmethylsiloxane complexes may include SIP6833.2; all of these are purchased from Gales Corporation. Other exemplary platinum-containing catalysts may include Catalyst OL, purchased from Wacker Chemie AG, and PC065, PC072, PC073, PC074, PC075, PC076, PC085, PC086, PC087, and PC088, purchased from United Chemical Technologies Inc.

[0097] Exemplary rhodium-containing materials may include tris(dibutyl sulfide) rhodium trichloride, product code INRH078, purchased from Gales.

[0098] Not wanting to be bound by any particular theory, it is believed that platinum catalysts react with vinyl silicone oil and hydrogen-containing silicone oil.

[0099] In one exemplary embodiment, the catalyst may be provided in the form of a mixture with one or more silicone oils. In one exemplary embodiment, a platinum-containing catalyst may be incorporated into a functional silicone oil, such as KE-1012-A, KE-1031-A, KE-109E-A, KE-1051J-A, KE-1800T-A, KE1204A, and KE1218A purchased from Shin-Etsu Chemical Co., Ltd., or SILBIONE purchased from Bluestar Corporation. ® RT Gel 4725 SLD A, such as SilGel purchased from Wacker Chemie. ® 612 A, ELASTOSIL ® LR 3153A, ELASTOSIL ® LR 3003A, ELASTOSIL ® LR 3005A, SEMICOSIL ® 961A, SEMICOSIL ® 927A, SEMICOSIL ® 205A, SEMICOSIL® 9212A, SILPURAN ® 2440, such as Silopren purchased from Momentive. ® LSR 2010A, such as XIAMETER purchased from Dow Corning. ® RBL-9200 A, XIAMETER ® RBL-2004 A, XIAMETER ® RBL-9050 A, XIAMETER ® RBL-1552 A, Silastic ® FL 30-9201 A, Silastic ® 9202 A, Silastic ® 9204 A, Silastic ® 9206 A, SYLGARD ® 184A, Dow Corning ® QP-1 A, Dow Corning ® C6 A、Dow Corning ® CV9204 A.

[0100] TIM may include one or more catalysts in amounts of 5 ppm, 10 ppm, 50 ppm to 100 ppm, 150 ppm, 200 ppm, or any range using any two of the foregoing values ​​as endpoints, wherein the amounts are based on the total weight of the silicone oil, such as 5 ppm to 200 ppm, 10 ppm to 150 ppm, or 50 ppm to 100 ppm.

[0101] F. Inhibitors

[0102] TIM contains one or more inhibitors for inhibiting or limiting silicone oil crosslinking. Inhibitors may include at least one of an alkynyl compound and a polyvinyl functional polysiloxane. The polyvinyl functional polysiloxane may be a vinyl-terminated polydimethylsiloxane. The alkynyl compound may be an alkynyl alcohol compound.

[0103] Exemplary inhibitors may include alkynols, such as 1-ethynyl-1-cyclohexanol, 2-methyl-3-butyn-2-ol, 2-phenyl-3-butyn-2-ol, 2-ethynyl-isopropanol, 2-ethynyl-butane-2-ol, and 3,5-dimethyl-1-hexyn-3-ol; silylated alkynols, such as trimethyl(3,5-dimethyl-1-hexyn-3-oxy)silane, dimethyl-bis-(3-methyl-1-butyn-oxy)silane, methylvinylbis(3-methyl-1-butyn-3-oxy)silane, and ((1,1-dimethyl-2-propynyl)oxy)trimethylsilane; and unsaturated carboxylic acid esters, such as diallyl maleate, dimethyl maleate, diethyl fumarate, diallyl fumarate, and bis-2-methoxy-1-methylethyl maleate, methyl... Monooctyl maleate, monoisooctyl maleate, monoallyl maleate, monomethyl maleate, monoethyl fumarate, monoallyl fumarate, 2-methoxy-1-methylethyl maleate; fumarate / alcohol mixtures, such as those where the alcohol is selected from benzyl alcohol or a mixture of 1-octanol and ethynylcyclohexyl-1-ol; conjugated enynes, such as 2-isobutyl-1-buten-3-yne, 3,5-dimethyl-3-hexen-1-yne, 3-methyl-3-penten-1-yne, 3-methyl-3-hexen-1-yne, 1-ethynylcyclohexene, 3-ethyl-3-buten-1-yne and 3-phenyl-3-buten-1-yne; vinylcyclosiloxanes, such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and mixtures of conjugated enynes and vinylcyclosiloxanes. In one exemplary embodiment, the addition inhibitor is selected from 2-methyl-3-butyn-2-ol or 3-methyl-1-pentyn-3-ol.

[0104] In some exemplary embodiments, the vinyl-terminated polydimethylsiloxane in ethynylcyclohexanol may be Pt inhibitor 88, available from Wacker Chemie AG. Without wishing to be bound by any particular theory, it is known that platinum catalysts form complexes with ethynylcyclohexanol and the vinyl-terminated polydimethylsiloxane, as shown below.

[0105]

[0106] It is believed that the formation of the complex reduces the catalyst activity at room temperature, thus preserving the dispensability and wettability of the TIM. At higher curing step temperatures, Pt is released from the complex and facilitates the hydrosilylation of vinyl-functionalized and hydride-functionalized silicone oils, providing better control over "crosslinking".

[0107] In some exemplary embodiments, based on the total weight of the TIM, the TIM may include one or more inhibitors in amounts of: 0.01 wt%, 0.02 wt%, 0.05 wt% to 0.10 wt%, 0.25 wt%, 0.50 wt%, or any range defined between any two of the foregoing values, such as 0.01 wt% to 0.50 wt%, 0.02 wt% to 0.25 wt%, or 0.05 wt% to 0.10 wt%. In one exemplary embodiment, the TIM includes an amount of inhibitor of 0.01 wt% to 0.02 wt%.

[0108] Without being bound by any particular theory, it is believed that, in the absence of inhibitors, vinyl-functionalized silicone oils react very rapidly with hydride-functionalized silicone oils based on the addition-hydrosilanization mechanism to form a solid phase that cannot be automatically distributed by typical methods.

[0109] G. Release agent

[0110] TIM compositions may include release agents. Release agents may be used in combination with coupling agents, as discussed further below. The combination of release agents and coupling agents can increase the dispensing rate of TIM in the syringe and also has a lubricating effect.

[0111] Release agents can be interfacial coatings applied to two surfaces that tend to adhere to each other, facilitating demolding, smoothing, and cleaning. The specific working principle of release agents used in TIM mold casting can be summarized as follows: The polar chemical bonds of the TIM interact with the mold surface to form an adsorbed film with regenerative charge. The silicon-oxygen bonds in the polysiloxane can be considered weak dipoles (Si+-O-). When the release agent is spread in a unidirectional arrangement on the mold surface, the molecules can adopt a unique extended chain configuration. Free surfaces can be covered by alkyl groups in a densely packed manner, and the release ability increases with the density of alkyl groups. However, when alkyl groups occupy large steric hindrances, the extended configuration may be restricted, and the release ability may decrease.

[0112] The molecular weight and viscosity of the release agent can also be related to the release properties of TIM. When the molecular weight of the release agent is small, the spreadability may be good, but the heat resistance may be poor. According to the active substances, it can be divided into six series: (1) Silicon series - mainly siloxane compounds, silicone oil, silicone resin methyl branched silicone oil, methyl silicone oil, emulsified methyl silicone oil, hydrogen-containing methyl silicone oil, silicone grease, silicone resin, silicone rubber, silicone rubber toluene solution; (2) Wax series - plant, animal, synthetic paraffin wax; microcrystalline wax; polyethylene wax, etc.; (3) Fluorine series - polytetrafluoroethylene with the best isolation performance and less mold contamination, but higher cost; fluororesin powder; fluororesin coating, etc.; (4) Surfactant series - metal soap (anionic), EO, PO derivatives (nonionic); (5) Inorganic powder series - talc, mica, clay, white clay, etc.; (6) Polyether series - a mixture of polyether and oil, with good heat resistance and chemical properties, and mostly used in some rubber industries where silicone oil is restricted. Its cost is higher than that of the silicone oil series.

[0113] The release agent may be alkyl ester polydimethylsiloxane. The weight-average molecular weight (Mw) of the alkyl ester polydimethylsiloxane release agent may be as low as 8,000 Daltons or 10,000 Daltons, or as high as 20,000 Daltons or 30,000 Daltons, or within any range defined between any two of the foregoing values, as determined by gel permeation chromatography (GPC).

[0114] Based on the total weight of the TIM, the TIM may include one or more release agents in amounts such as 0 wt%, 0.1 wt%, 0.2 wt% to 0.4 wt%, 0.5 wt%, 0.6 wt%, or any range defined between any two of the foregoing values, such as 0 wt% to 0.6 wt%, 0.1 wt% to 0.5 wt%, or 0.2 wt% to 0.4 wt%. In one exemplary embodiment, the TIM contains about 0.4 wt% of release agent.

[0115] H. Colorants / Pigments

[0116] Thermal interface materials may include colorants / pigments, such as inorganic pigments.

[0117] In some exemplary embodiments, the colorant is an inorganic pigment selected from the group consisting of: α-Fe2O3; α-Fe2O3·H2O and Fe3O4.

[0118] In some exemplary embodiments, the colorant is an organic pigment. In more specific embodiments, the colorant is Fe3O4, such as commercially available iron black.

[0119] In some exemplary embodiments, based on the total weight of the TIM, the TIM comprises pigment in amounts of: 0.01 wt%, 0.02 wt%, 0.04 wt% to 0.06 wt%, 0.08 wt%, 0.10 wt%, or any range defined between any two of the foregoing values, such as 0.01 wt% to 0.10 wt%, 0.02 wt% to 0.08 wt%, or 0.04 wt% to 0.06 wt%.

[0120] I. Coupling agents

[0121] The thermal interface material compositions provided in this disclosure may comprise one or more coupling agents. Exemplary coupling agents include silane coupling agents having the general formula Y-(CH2)n-Si-X3, wherein Y is an organic functional group and X is a hydrolyzable group. The organic functional group Y includes alkyl, epoxypropoxy, acryloyloxy, methacryloxy, amine, or combinations thereof. The hydrolyzable group X includes alkoxy and acetoxy groups. In some exemplary embodiments, the silane coupling agent comprises alkyltrialkoxysilanes. Exemplary alkyltrialkoxysilanes include decyltrimethoxysilane, undecyltrimethoxysilane, hexadecyltrimethoxysilane, octadecyltrimethoxysilane, or dodecyltrimethoxysilane. In one exemplary embodiment, the TIM comprises dodecyltrimethoxysilane as a coupling agent, as shown in the following formula.

[0122]

[0123] Coupling agents can increase the dispersibility and wettability of TIM compositions.

[0124] The thermal interface material composition provided in this disclosure may include one or more coupling agents in weight percentages of, for example, 0 wt%, 0.02 wt%, 0.04 wt% to 0.08 wt%, 0.10 wt%, 0.12 wt%, or any range using any two of the foregoing values ​​as endpoints, wherein the weight percentage is based on the total weight of the TIM composition. For example, the one or more coupling agents may account for 0 wt% to 0.12 wt%, 0.02 wt% to 0.10 wt%, and 0.04 wt% to 0.08 wt% of the total weight of the TIM composition.

[0125] II. Properties of Thermally Conductive Hybrid Thermal Interface Materials

[0126] A. Thermal conductivity

[0127] Thermal conductivity describes the rate at which heat is transferred through a unit cross-sectional area of ​​a material via conduction. Thermal interface materials are used to conduct heat from electrical components to heat sinks. This allows electrical components to avoid overheating or damage due to heat during use.

[0128] The thermal interface materials of this disclosure can exhibit relatively high thermal conductivity. For example, the thermally conductive hybrid thermal interface materials provided in this disclosure may include thermal conductivity values ​​of, for example, 7 W / (mk), 8 W / (mk), 9 W / (mk) to 10 W / (mk), 11 W / (mk), 12 W / (mk), 13 W / (mk), 14 W / (mk), or any range using any two of the foregoing values ​​as endpoints, as determined according to ASTM D5470. For example, thermal conductivity may be between 7 W / (mk) and 14 W / (mk), between 8 W / (mk) and 13 W / (mk), between 9 W / (mk) and 12 W / (mk), and between 10 W / (mk) and 11 W / (mk). In one exemplary embodiment, the thermal interface material exhibits a thermal conductivity of 13 W / (mk) as determined according to ASTM D5470.

[0129] Thermal resistance (TI) testing characterizes the ability of a composition to dissipate heat from one electrical component to the rest of an electrical device. The gallium-based thermal interface materials disclosed herein can have TI in, for example, the range of 0.01 °C·cm² / W or 0.06 °C·cm² / W as measured according to ASTM D5470. In one exemplary embodiment, the thermal interface material exhibits a thermal resistance from 0.30 °C·cm² / W to 0.65 °C·cm² / W as measured by ASTM D5470.

[0130] B. Vertical stability

[0131] Vertical stability testing determines whether the TIM material will crack and slip, or experience oil seepage (or separation of material components) during device use. To test vertical stability, TIM material is added between a glass panel and an aluminum or copper panel. The pane is exposed to temperature cycling to observe whether the TIM material cracks or slips. Traditional TIM hybrid products may have issues with dropping and cracking during temperature cycling tests. If the TIM material cracks or slips, the thermal conductivity of the TIM material on the device may decrease, potentially leading to product failure.

[0132] The TIM material disclosed herein exhibits good vertical stability. For example, the thermally conductive hybrid thermal interface material provided herein experiences TIM material slippage of less than 30%, less than 25%, less than 20%, or less than 15% during vertical stability testing, or within any range using any two of the aforementioned values ​​as endpoints. Figures 2A to 2C As shown, the vertical stability of the TIM material of this invention and the comparative TIM material were tested. Figure 2AIn the above-mentioned test, the vertical stability of the TIM material was compared. The comparison TIM material exhibited over 20% cracking and slippage, but no oil seepage. Figure 2B and Figure 2C As seen in the test, the TIM material of the present invention exhibits less than 20% material cracking or slippage and no oil seepage.

[0133] III. Application of thermal interface materials

[0134] The thermal interface material compositions disclosed herein can be used as thermal interface materials in various electronic component environments.

[0135] For example, Figure 1A An electronic chip 34, a heat sink 36, and a heat fin 32 are schematically shown, wherein a first thermal interface material (TIM) 10A connects the heat sink 32 and the heat sink 36, and a second thermal interface material 10B connects the heat sink 36 and the electronic chip 34. One or both of the thermal interface materials 10A and / or 10B may comprise the thermally conductive hybrid thermal interface material composition previously described. Figure 1B An exemplary thermal interface material 10 is shown, which serves as a thermal interface layer and is designated as a TIM positioned between an electronic chip 34 and a heat sink 32, such that a first surface of TIM 10 contacts the surface of the electronic chip 34 and a second surface of TIM 10 contacts the surface of the heat sink 32. Figure 1A Similarly, TIM 10 may include the previously described thermally conductive hybrid thermal interface material composition. Figure 1C An exemplary thermal interface material 10 is shown, which serves as a thermal interface material positioned between the heat sink 36 and the heat sink 32, such that a first surface of the TIM 10 contacts the surface of the heat sink 36 and a second surface of the TIM 10 contacts the surface of the heat sink 32. Figure 1A and Figure 1B Similarly, TIM 10 may include the previously described thermally conductive hybrid thermal interface material composition. Figure 1D An exemplary thermal interface material 10 is shown, which serves as a thermal interface material positioned between an electronic chip 34 and a heat sink 36, such that a first surface of the TIM 10 contacts the surface of the electronic chip 34 and a second surface of the TIM 10 contacts the surface of the heat sink 36. Figure 1A , Figure 1B and Figure 1C Similarly, TIM 10 may include the previously described thermally conductive hybrid thermal interface material composition.

[0136] The thermally conductive hybrid TIM disclosed herein can be applied to a substrate using various printing processes, including stencil printing. Using a stencil provides greater control and / or efficiency in applying the TIM to electrical components. For example, by using a stencil, the TIM can be repeatedly applied to many components with the same pattern. The stencil can be made in various shapes, allowing the TIM to be applied to a wide variety of electrical components. The TIM can be printed onto a substrate, which can be a conductive metal substrate, such as a copper or aluminum substrate. In some cases, the conductive substrate can be a nickel-plated substrate, such as a nickel-plated copper or nickel-plated aluminum substrate.

[0137] For example, the components of the thermally conductive hybrid TIM composition provided in this disclosure can be combined into a paste. The paste can be printed onto a coated metal substrate (such as a nickel-plated copper substrate or a nickel-plated aluminum substrate), for example, by means of a squeegee and stencil process. The top portion of the substrate can be covered with a stencil, wherein the stencil has a thickness (t) and includes a plurality of openings arranged in a grid. The openings can be based on various geometries, including hexagonal geometries, and each opening geometry has a length (l) (or diameter). The distance (a) between each opening around the grid can be based on the thickness (t) of the stencil, wherein the distance (a) is proportional to (t). For example, when the stencil has a relatively large thickness (t), the distance (a) between the openings can be relatively large, or conversely, when the thickness (t) is relatively small, the distance (a) between the openings can also be relatively small. The distance (a) between the openings can also be proportional to the length (l) of the opening, such that with a larger value of length (l), the distance (a) between the openings can also be relatively large. At least each of the variables (a), (l) and (t) can be adjusted individually or in combination to deposit a thermally conductive mixed TIM paste of the desired thickness onto the coated metal substrate.

[0138] For example, a pattern is cut into the steel substrate using a laser or other process to create clean edges on the stencil geometry. Some processes (such as conventional stamping) can be avoided because they may leave curled edges or sharp features, which can lead to uneven stencils or scratches on the heatsink surface. The stencil feature size can be small enough that the straightness of the scraper edge does not affect the thickness of the paste (i.e., wide openings should be avoided). Honeycomb patterns can be used because they provide a uniform distribution and can be easily specified on a two-dimensional drawing. The paste can be pressed into the stencil feature using a scraper, and the pattern allows the scraper to remain parallel to the heatsink at all points. The pattern remains on the surface until the module is pressed down and subjected to temperature cycling, at which point the paste flows to fill the voids. The shape, size, and spacing of the holes, as well as the thickness of the stencil, determine how thick the resulting paste is once the module is installed.

[0139] For example, when the length of the pattern cut into the steel plate (e.g., in a honeycomb orientation) is 2.0 mm and the spacing between the individual pattern cuts is 0.5 mm, the thickness of the resulting paste can be approximately 0.08 mm. In another example, when the length of the honeycomb pattern is 3.0 mm and the spacing between the individual pattern cuts is 0.75 mm, the thickness of the resulting paste can be approximately 0.1 mm. In yet another example, when the length of the honeycomb pattern is 4.0 mm and the spacing between the individual pattern cuts is 1 mm or 2 mm, the thickness of the resulting paste can be approximately 0.12 mm and in the range of 0.15 mm to 0.2 mm, respectively.

[0140] Example

[0141] Example 1

[0142] Two diamond-containing fillers, N21 and N23, were prepared according to the formulations in Table 1.

[0143] To prepare N21, zinc oxide, aluminum oxide, and diamond powder were weighed in the amounts shown in Table 1 and mixed at 1200 rpm for 2 minutes using a high-speed mixer. The mixture was then mixed three times to obtain N21.

[0144] To prepare N23, zinc oxide, aluminum oxide, aluminum nitride, and diamond powder were weighed in the amounts shown in Table 1 and mixed at 1200 rpm for 2 minutes using a high-speed mixer. The mixture was then mixed three times to obtain N23.

[0145] Table 1: Diamond-containing filler formulations

[0146]

[0147] Prepare a comparative TIM composition and two TIM compositions of the present invention according to the formulations in Table 2.

[0148] Table 2: Thermally Conductive Mixed TIM Formulations

[0149]

[0150] Weigh out the silicone oil, dispersant, crosslinking agent and inhibitor and add them to a high-speed mixer at 2000 rpm for 2 minutes to produce the silicone oil component.

[0151] Add diamond-containing fillers, coupling agents, release agents, and pigments to a high-speed mixer at 2000 rpm for 4 minutes.

[0152] Add the catalyst to the aforementioned components in a high-speed mixer at 2000 rpm for 2 minutes.

[0153] The composition was then added to a vacuum mixer and defoamer at a vacuum of -0.1 MPa for 6 minutes to produce a thermally conductive mixed TIM.

[0154] Example 2

[0155] The thermal resistance and thermal conductivity of each thermally conductive hybrid TIM composition (Examples 1, 2 and 3) were tested.

[0156] The thermal conductivity of TIM compositions is tested using the Analysis Tech, Inc. Thermal Interface Material Tester, or "TIM Tester." The TIM Tester measures the thermal conductivity and thermal resistance in materials with medium to high thermal conductivity and is ideally suited for measuring thermal interface materials used in electronic packaging. The TIM Tester conforms to test method ASTM D-5470-06, in which the thermal resistance of the test sample is calculated by dividing the temperature difference across the sample by the heat flowing through it.

[0157] Table 3 shows the thermal conductivity of each embodiment.

[0158] Table 3: Thermal conductivity and impedance of TIM compositions

[0159]

[0160] Example 3

[0161] The vertical stability of each thermally conductive hybrid TIM composition of Comparative Example 1, Example 1 of the present invention, and Example 2 of the present invention under thermal cycling was tested. To test vertical stability, the flow rates listed in Table 4 were used for each sample.

[0162] Table 4: Distribution rates of Examples 1, 2 and 3

[0163]

[0164] Note: To measure the flow rate of the TIM sample, use a nozzleless 30 cc syringe and dispense the TIM sample for 1 minute at a pressure of 0.6 MPa using a dispenser tool. After 1 minute, weigh the dispensed TIM sample.

[0165] The vertical stability of the TIM composition was tested using the method described above. The TIM composition was placed between glass and aluminum clamps and immersed in a thermal cycling chamber with a 0.8 mm gap, cycling 1100 times from -40°C to 120°C. The rise time was 10°C per minute, and the peak / low-temperature swelling time was 20 minutes. Figures 2B to 2C As observed, the TIM compositions of the present invention all exhibit less than 20% material cracking or slippage, and no visible material component separation / oil seepage. However, as Figure 2A As observed, the TIM material composition showed over 20% cracking and slippage, with no oil seepage.

Claims

1. A thermal interface material, the thermal interface material comprising: Diamond-containing fillers; Silicone oil; and Multiple additives.

2. The thermal interface material according to claim 1, wherein the plurality of additives comprises: Dispersant; Crosslinking agent; catalyst; Inhibitors; Release agent; pigment; and Coupling agent.

3. The thermal interface material according to claim 1, wherein the diamond-containing filler accounts for 93% to 98% by weight of the total weight of the thermal interface material.

4. The thermal interface material according to claim 1, wherein the diamond-containing filler comprises: Zinc oxide; Alumina (D50 = 2μm to 5μm); Alumina (D50 = 25 μm to 45 μm); and Diamond (D50 = 110μm to 130μm).

5. The thermal interface material according to claim 4, wherein: Zinc oxide comprises 0.2% to 2.5% by weight of the total weight of the diamond-containing filler. Alumina (D50 = 2 μm to 5 μm) accounts for 5% to 20% by weight of the total weight of the blended diamond filler. Alumina (D50 = 25 μm to 45 μm) accounts for 30% to 65% by weight of the total weight of the blended diamond filler; and Diamond (D50 = 110 μm to 130 μm) accounts for 5% to 15% by weight of the total weight of the blended diamond filler.

6. The thermal interface material according to claim 1, wherein the blended diamond filler comprises: Zinc oxide; Alumina (D50 = 2μm to 5μm); Alumina (D50 = 10 μm to 15 μm); Aluminum nitride; and Diamond (D50 = 80μm to 100μm).

7. The thermal interface material according to claim 6, wherein: The zinc oxide accounts for 0.2% to 2.5% by weight of the total weight of the blended diamond filler; The alumina (D50 = 2 μm to 5 μm) accounts for 10% to 30% by weight of the total weight of the blended diamond filler. The alumina (D50 = 10 μm to 15 μm) accounts for 5% to 15% by weight of the total weight of the blended diamond filler. The aluminum nitride comprises 40% to 65% by weight of the total weight of the blended diamond filler; and The diamond (D50 = 80 μm to 100 μm) accounts for 2% to 10% by weight of the total weight of the blended diamond filler.

8. The thermal interface material according to claim 1, wherein the thermal interface material has a thermal conductivity of 10 W / (mk) to 13 W / (mk) as determined according to ASTM D5470.

9. The thermal interface material according to claim 1, wherein the silicone oil accounts for 2.5% to 4.5% by weight of the total weight of the thermal interface material.

10. The thermal interface material according to claim 2, wherein the pigment accounts for 0.01% to 0.10% by weight of the total weight of the thermal interface material.

11. A method for applying a thermal interface material to a substrate, the method comprising: Each of the thermally conductive filler, silicone oil, and various additives is combined to form the thermal interface material; The thermally conductive filler includes a blend of diamond fillers; as well as The thermal interface material is applied to the metal substrate.

12. The method of claim 11, wherein the blended diamond filler comprises zinc oxide, aluminum oxide (D50 = 2 μm to 5 μm), aluminum oxide (D50 = 25 μm to 45 μm), and diamond (D50 = 110 μm to 130 μm).

13. The method of claim 11, wherein the blended diamond filler comprises zinc oxide, aluminum oxide (D50 = 2 μm to 5 μm), aluminum oxide (D50 = 10 μm to 15 μm), aluminum nitride, and diamond (D50 = 80 μm to 100 μm).

14. An electronic component, the electronic component comprising: Heat sink; Electronic chips; and A thermal interface material, wherein the thermal interface material is positioned between the heat sink and the electronic chip, wherein the thermal interface material comprises: Thermally conductive filler The thermally conductive filler includes a blend of diamond fillers; silicone oil; and Multiple additives.

15. The electronic component of claim 14, wherein the plurality of additives comprises: Dispersant; Crosslinking agent; catalyst; Inhibitors; Release agent; Pigments; and Coupling agent.

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