Heat-conducting UV adhesive for GaN high-electron-mobility transistor and preparation method of heat-conducting UV adhesive

Abstract

The invention discloses a heat-conducting UV adhesive for a GaN high-electron-mobility transistor and a preparation method of the heat-conducting UV adhesive. The heat-conducting UV adhesive comprises the following components in percentage by weight: polyurethane acrylic resin, an active diluting monomer, a photoinitiator, diamond copper-plated powder and an auxiliary agent. The heat-conducting UV adhesive is used for bonding a diamond substrate and a GaN epitaxial material of a GaN high-electron-mobility transistor device, can overcome the problem that diamond is difficult to bond, effectively bonds the diamond, is firm in bonding, lasting in bonding effect, excellent in heat-conducting property, extremely low in thermal expansion coefficient, excellent in high-temperature resistance and weather resistance, stable in property and high in reliability. And the operation required by curing is simple, convenient and feasible, and the cost is controllable and is far lower than that of a traditional combination method.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal conductive materials, and in particular to a thermal conductive UV adhesive for a GaN high electron mobility transistor and a preparation method thereof. Background Art

[0002] GaN high electron mobility transistors (HEMTs) have been successfully applied to high-frequency, high-temperature, high-power electronic devices due to their advantages such as high breakdown field strength, high conversion efficiency, and low on-resistance. However, with the development trend of miniaturization and high power, the reliability and stability of GaN microwave power devices face serious challenges. With the increase of power density of GaN-based power devices, the heat accumulation effect in the active area of ​​the chip is rapidly enhanced, resulting in a serious deterioration of its various performance indicators, so that its power advantage cannot be fully utilized. Therefore, the heat dissipation problem has become one of the main technical bottlenecks restricting the further development and widespread application of GaN power devices. Using high thermal conductivity diamond as a substrate or heat sink for GaN power devices can significantly improve the heat dissipation capacity of power devices and realize high-frequency and high-power applications. At present, there are three ways in the industry to realize the combination of diamond substrate and GaN epitaxial material. The first is to directly epitaxially grow GaN on a diamond substrate; this method is difficult to grow and has poor electrical properties, and requires more sophisticated interface control and stress management during epitaxial growth and the final cooling process. The second method is to grow diamond on the GaN600HEMT structure; generally, chemical vapor deposition (CVD) technology above 600°C is used to grow diamond on SiN x The third method is GaN / diamond bonding technology. Since this technology is generally bonded at a high temperature of 800°C, it greatly limits the product types. In summary, the above three methods are all costly and have strict conditions, and alternative solutions are urgently needed.

[0003] UV glue, also known as photosensitive glue or ultraviolet light curing glue, is an adhesive that can cure quickly under ultraviolet light. It has the characteristics of fast curing, high bonding strength, strong weather resistance, environmental protection and pollution-free, and a wide range of applications. It can maintain stable performance in harsh environments such as high temperature, ultraviolet light, and moisture, and has high strength and toughness after curing. It can withstand large tensile and shear forces on a variety of materials, such as glass, plastic, and metal, thereby achieving reliable bonding. In addition, the application and curing of UV glue are very simple, which is convenient for large-scale application.

[0004] Diamond is composed of a simple carbon main chain, with excellent thermal conductivity, thermal conductivity of up to 2000 ~ 2200w / m K, thermal conductivity value is 5 times that of copper, thermal conductivity far exceeds most traditional materials, is a very potential next generation thermal conductive material. In addition, it also has the advantages of low thermal expansion coefficient, excellent thermal shock resistance, etc., in the thermal interface materials, composite materials and other cutting-edge applications have shown great potential.

[0005] The present invention proposes to use a UV glue to bond GaN-diamond to replace the original "growth" solution. Summary of the invention

[0006] In order to solve the above technical problems, the purpose of the present invention is to provide a thermally conductive UV adhesive for GaN high electron mobility transistors and a preparation method thereof. The thermally conductive UV adhesive is used to bond the diamond substrate of the GaN high electron mobility transistor device to the GaN epitaxial material, which can overcome the difficulty of diamond bonding, effectively bond the diamond, firmly bond, and have a long-lasting bonding effect, and has excellent thermal conductivity, extremely low thermal expansion coefficient, excellent high temperature and weather resistance, stable properties, simple and easy operation required for curing, and controllable cost, which is far lower than traditional bonding methods.

[0007] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0008] A thermally conductive UV adhesive for a GaN high electron mobility transistor comprises the following components in terms of weight percentage:

[0009]

[0010] Preferably, the polyurethane acrylic resin is one or a mixture of two or more of polyether-modified polyurethane acrylic resin, polyester-modified polyurethane acrylic resin, and polycarbonate-modified polyurethane acrylic resin.

[0011] Preferably, the active diluent monomer is one or a mixture of two of isobornyl acrylate, tetrahydrofuran acrylate, lauryl acrylate, acryloyl morpholine, cyclotrimethylolpropane formal acrylate, tricyclodecane dimethanol diacrylate, and tripropylene glycol diacrylate.

[0012] Preferably, the photoinitiator is one or a mixture of two or more of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxycyclohexyl phenyl ketone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0013] Furthermore, the diamond copper-plated powder is obtained by chemically plating copper on the surface of diamond powder.

[0014] Furthermore, the thermal conductivity of the diamond powder is 1300-2100 W / m·K, its microscopic morphology is irregular, and its particle size is 1-3 μm.

[0015] Preferably, the auxiliary agent includes one or more of a dispersant, an antioxidant, a coupling agent, and a defoaming agent.

[0016] The present invention further provides a method for preparing a thermally conductive UV adhesive for a GaN high electron mobility transistor, comprising the following steps:

[0017] (1) pre-treating the diamond powder, wherein the pre-treatment includes degreasing, roughening, sensitization, and activation treatment;

[0018] (2) performing surface copper plating on the pretreated diamond powder by using a chemical copper plating process to obtain diamond copper-plated powder;

[0019] (3) Weighing polyurethane acrylic resin, active diluent monomer, photoinitiator, diamond copper-plated powder, and additives respectively according to mass percentage, stirring the weighed materials evenly, and then vacuuming to remove bubbles inside the glue to obtain the thermal conductive UV glue for GaN high electron mobility transistors.

[0020] Furthermore, the chemical plating solution used in the chemical copper plating process in step (2) includes a reducing plating solution, a Cu salt plating solution, and a pH adjusting solution.

[0021] The present invention also provides an application of the thermally conductive UV adhesive to a GaN high electron mobility transistor. Specifically, during application, the thermally conductive UV adhesive is used to bond a diamond substrate and a GaN epitaxial material of a GaN high electron mobility transistor device.

[0022] The beneficial effects of the present invention are:

[0023] (1) The thermally conductive UV adhesive of the present invention is used to bond the diamond substrate of the GaN high electron mobility transistor device to the GaN epitaxial material, overcoming the difficulty of bonding due to the low surface energy of the diamond, and can achieve a firm bond to the diamond surface with a long-lasting bonding effect. It has excellent thermal conductivity and a low thermal expansion coefficient, which can meet the requirements of thermally conductive materials. It also has excellent high temperature resistance and weather resistance. The adhesive application and curing operations are simple and easy during application.

[0024] (2) The present invention utilizes a chemical copper plating process to dope part of the diamond surface with copper, which effectively enhances the dispersibility of diamond powder in the UV glue system, making it possible to add a high proportion of powder to the UV glue, and effectively improving the thermal conductivity of the UV glue;

[0025] (3) The thermally conductive UV adhesive of the present invention uses diamond-plated copper powder. Since diamond has both high thermal conductivity and low thermal expansion coefficient, the thermally conductive UV adhesive meets the performance requirements of packaging materials.

[0026] (4) The present invention can add suitable additives to the colloid according to the application scenario, thereby effectively improving the key properties of the colloid such as high temperature aging resistance and adhesion, and effectively extending the service life of the UV glue.

[0027] (5) Before the thermally conductive UV adhesive of the present invention is used to bond the diamond substrate of the transistor device to the GaN epitaxial material, the diamond surface is firstly subjected to plasma treatment to activate the diamond surface which is difficult to bond, which can greatly improve the bonding strength to the diamond and solve the problem of difficult bonding of diamond.

[0028] (6) The thermally conductive UV adhesive of the present invention is used for bonding the diamond substrate and the GaN epitaxial material of the transistor device. Compared with the prior art, it does not require expensive equipment, is simple to operate, has mild conditions, and has low production costs, and can be used for large-scale production. DETAILED DESCRIPTION

[0029] The technical solutions in the present invention will be described clearly and completely below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The present invention provides a thermally conductive UV adhesive for a GaN high electron mobility transistor, which comprises the following components in terms of weight percentage:

[0031]

[0032]

[0033] The polyurethane acrylic resin is one or a mixture of two or more of polyether-modified polyurethane acrylic resin, polyester-modified polyurethane acrylic resin and polycarbonate-modified polyurethane acrylic resin.

[0034] The active diluent monomer is one or a mixture of two of isobornyl acrylate, tetrahydrofuran acrylate, lauryl acrylate, acryloyl morpholine, cyclotrimethylolpropane formal acrylate, tricyclodecane dimethanol diacrylate, and tripropylene glycol diacrylate.

[0035] Wherein, the photoinitiator is one or a mixture of two or more of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxycyclohexyl phenyl ketone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0036] The diamond copper-plated powder is obtained by chemically plating copper on the surface of diamond powder. The thermal conductivity of the diamond powder is 1300-2100 W / m·K, its microscopic morphology is irregular, and its particle size is 1-3 μm.

[0037] The auxiliary agent includes one or more of a dispersant, an antioxidant, a coupling agent, and a defoaming agent.

[0038] The method for preparing a thermally conductive UV adhesive for a GaN high electron mobility transistor comprises the following steps:

[0039] (1) Pretreatment of diamond powder, including degreasing, roughening, sensitization and activation. Specifically, degreasing, roughening, sensitization and activation are performed on diamond powder using alkali solution, acid solution, oxidant and catalyst. Degreasing is mainly to remove grease, stains and other organic pollutants on the surface of diamond powder. Roughening can form some tiny pits and cracks on the surface of diamond to increase the surface roughness of diamond. Sensitization is to adsorb easily oxidizable substances on the surface of diamond powder without catalytic ability. Activation is to adsorb metal ions with catalytic activity for the reduction of Cu on the surface of diamond powder particles.

[0040] (2) The surface of the pretreated diamond powder is subjected to copper plating treatment by a chemical copper plating process to obtain diamond copper-plated powder; the chemical copper plating process is specifically as follows:

[0041] First, a chemical plating solution is prepared; three plating solutions containing one or more of copper salt, reducing agent, pH adjusting agent, chelating agent, defoaming agent and stabilizer are prepared: solution A, solution B and solution C, which are respectively a reducing plating solution, a Cu salt plating solution and a pH adjusting solution.

[0042] Then, copper plating and cleaning are carried out; first, the pH of A and B liquids are adjusted to the range of 12 to 13 using liquid C. Liquid A is placed in a burette and liquid B is placed in a beaker, and the two liquids are preheated to 45°C; the ultrasonic constant temperature water bath is turned on and the constant temperature is set to 45°C; a certain amount of pretreated diamond powder is placed in liquid B, and after stirring evenly, it is placed in an ultrasonic constant temperature water bath; the ultrasonic generator is turned on and liquid A is dripped into liquid B, at which time chemical plating begins; when the plating solution changes from blue to turbid gray, chemical plating ends. Filter the plating solution, rinse it with pure water until it is neutral, and then filter and dry it again to obtain diamond copper-plated powder.

[0043] (3) Weighing polyurethane acrylic resin, active diluent monomer, photoinitiator, diamond copper-plated powder, and additives respectively according to mass percentage, stirring the weighed materials evenly, and then vacuuming to remove bubbles inside the glue to obtain the thermal conductive UV glue for GaN high electron mobility transistors.

[0044] The thermally conductive UV adhesive can be applied to GaN high electron mobility transistors. Specifically, when applied, the thermally conductive UV adhesive is used to bond the diamond substrate of the GaN high electron mobility transistor device to the GaN epitaxial material. In addition, before bonding, the surface of the diamond substrate is first plasma treated to activate the diamond surface that is difficult to bond, which can greatly improve the bonding force to the diamond and solve the problem of difficult diamond bonding.

[0045] The present invention is further described below by means of specific examples.

[0046] Example 1

[0047] The thermally conductive UV adhesive for GaN high electron mobility transistor of Example 1 comprises the following components in terms of weight percentage:

[0048]

[0049] The polyurethane acrylic resin is a polyether-modified polyurethane acrylic resin; the active diluent monomer is a mixture of isobornyl acrylate, tetrahydrofuran acrylate and lauryl acrylate; and the photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0050] The diamond copper-plated powder is obtained by chemically plating copper on the surface of diamond powder. The thermal conductivity of the diamond powder is 1500W / m·K, its microscopic morphology is irregular, and the particle size is 1-3μm.

[0051] The auxiliary agents include dispersants, antioxidants and defoamers.

[0052] The method for preparing a thermally conductive UV adhesive for a GaN high electron mobility transistor comprises the following steps:

[0053] (1) Using alkali solution, acid solution, oxidant and catalyst to pre-treat diamond powder by degreasing, roughening, sensitizing and activating.

[0054] (2) The surface of the pretreated diamond powder is subjected to copper plating treatment by a chemical copper plating process to obtain diamond copper-plated powder; the chemical copper plating process is specifically as follows:

[0055] First, a chemical plating solution is prepared; three plating solutions containing one or more of copper salt, reducing agent, pH adjusting agent, chelating agent, defoaming agent and stabilizer are prepared: solution A, solution B and solution C, which are reducing plating solution, Cu salt plating solution and pH adjusting solution respectively.

[0056] Then, copper plating and cleaning are carried out; first, the pH of A and B liquids are adjusted to the range of 12 to 13 using liquid C. Liquid A is placed in a burette and liquid B is placed in a beaker, and the two liquids are preheated to 45°C; the ultrasonic constant temperature water bath is turned on and the constant temperature is set to 45°C; a certain amount of pretreated diamond powder is placed in liquid B, and after stirring evenly, it is placed in an ultrasonic constant temperature water bath; the ultrasonic generator is turned on and liquid A is dripped into liquid B, at which time chemical plating begins; when the plating solution changes from blue to turbid gray, chemical plating ends. Filter the plating solution, rinse it with pure water until it is neutral, and then filter and dry it again to obtain diamond copper-plated powder.

[0057] (3) Weighing polyurethane acrylic resin, active diluent monomer, photoinitiator, diamond copper-plated powder, and additives respectively according to mass percentage, stirring the weighed materials evenly, and then vacuuming to remove bubbles inside the glue to obtain the thermal conductive UV glue for GaN high electron mobility transistors.

[0058] Example 2

[0059] The thermally conductive UV adhesive for GaN high electron mobility transistor of Example 2 includes the following components in terms of weight percentage:

[0060]

[0061]

[0062] The polyurethane acrylic resin is a polyester-modified polyurethane acrylic resin; the active diluent monomer is a mixture of isobornyl acrylate, tetrahydrofuran acrylate and tripropylene glycol diacrylate; and the photoinitiator is 1-hydroxycyclohexyl phenyl ketone.

[0063] The diamond copper-plated powder is obtained by chemically plating copper on the surface of diamond powder. The thermal conductivity of the diamond powder is 1600 W / m·K, its microscopic morphology is irregular, and the particle size is 1-3 μm.

[0064] The auxiliary agents include dispersants, antioxidants and defoamers.

[0065] The preparation method of the thermally conductive UV adhesive of Example 2 is the same as that of Example 1.

[0066] Example 3

[0067] The thermally conductive UV adhesive for GaN high electron mobility transistor of Example 3 includes the following components in terms of weight percentage:

[0068]

[0069] The polyurethane acrylic resin is a polyester-modified polyurethane acrylic resin; the active diluent monomer is a mixture of isobornyl acrylate, tetrahydrofuran acrylate and tripropylene glycol diacrylate; and the photoinitiator is 1-hydroxycyclohexyl phenyl ketone.

[0070] The diamond copper-plated powder is obtained by chemically plating copper on the surface of diamond powder. The thermal conductivity of the diamond powder is 1600 W / m·K, its microscopic morphology is irregular, and the particle size is 1-3 μm.

[0071] The auxiliary agents include dispersants, antioxidants and defoamers.

[0072] The preparation method of the thermally conductive UV adhesive of Example 3 is the same as that of Example 1.

[0073] The specific implementation method of the thermal conductive UV adhesive of the above embodiment is: take a diamond substrate processed by a plasma processor, apply the thermal conductive UV adhesive on the diamond substrate of the transistor device, place the GaN epitaxial material, and then use a mercury lamp or LED lamp to irradiate the UV adhesive from the light-transmitting diamond surface; after a few seconds, the thermal conductive UV adhesive can be cured, and the diamond and GaN are firmly bonded.

[0074] The thermally conductive UV adhesives of Examples 1-3 were subjected to performance tests, and the performance test standards and methods were as follows:

[0075] Viscosity (cps): Brookfield DV-2T viscometer, 25°C, 52# rotor, 0.5 ml sample;

[0076] Thixotropy: The test method is the same as the test method for viscosity performance;

[0077] Thermal conductivity (w / m·K): Hotdisk thermal conductivity meter; ISO 22007-2:2022; after curing (365nm, 2000mW / cm 2 , 5s) test;

[0078] Shear strength (Mpa): Diamond substrate (plasma treatment)-GaN substrate bonded with thermally conductive UV adhesive as the test sample; GB / T 7124-2008; 365nm, 2000mW / cm 2 , 5s; tensile machine, 10mm / min;

[0079] Yellowing value: portable yellowing meter, 200℃, 2h, 0.2mm film thickness;

[0080] Body strength (Mpa): tensile testing machine, 100mm / min.

[0081] The performance test results are shown in Table 1.

[0082] Table 1

[0083]

[0084] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0085] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A thermally conductive UV adhesive for GaN high electron mobility transistors, characterized in that: It includes the following components in weight percentage:

2. The thermally conductive UV adhesive for GaN high electron mobility transistor according to claim 1, characterized in that: The polyurethane acrylic resin is one of polyether-modified polyurethane acrylic resin, polyester-modified polyurethane acrylic resin, and polycarbonate-modified polyurethane acrylic resin, or a mixture of two or more thereof.

3. The thermally conductive UV adhesive for GaN high electron mobility transistor according to claim 1, characterized in that: The active diluent monomer is one or a mixture of two of isobornyl acrylate, tetrahydrofuran acrylate, lauryl acrylate, acryloyl morpholine, cyclotrimethylolpropane formal acrylate, tricyclodecane dimethanol diacrylate and tripropylene glycol diacrylate.

4. The thermally conductive UV adhesive for GaN high electron mobility transistor according to claim 1, characterized in that: The photoinitiator is one or a mixture of two or more of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxycyclohexyl phenyl ketone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and 2-hydroxy-2-methyl-1-phenyl-1-propanone.

5. The thermally conductive UV adhesive for GaN high electron mobility transistor according to claim 1, characterized in that: The diamond copper-plated powder is obtained by chemically plating copper on the surface of diamond powder.

6. The thermally conductive UV adhesive for GaN high electron mobility transistor according to claim 1, characterized in that: The thermal conductivity of the diamond powder is 1300-2100 W / m·K, the microscopic morphology is irregular, and the particle size is 1-3 μm.

7. The thermally conductive UV adhesive for GaN high electron mobility transistor according to claim 1, characterized in that: The auxiliary agent includes one or more of a dispersant, an antioxidant, a coupling agent, and a defoaming agent.

8. A method for preparing a thermally conductive UV adhesive for a GaN high electron mobility transistor according to any one of claims 1 to 7, characterized in that: The steps include: (1) pre-treating the diamond powder, wherein the pre-treatment includes degreasing, roughening, sensitization, and activation treatment; (2) performing surface copper plating on the pretreated diamond powder by using a chemical copper plating process to obtain diamond copper-plated powder; (3) Weighing polyurethane acrylic resin, active diluent monomer, photoinitiator, diamond copper-plated powder, and additives respectively according to mass percentage, stirring the weighed materials evenly, and then vacuuming to remove bubbles inside the glue to obtain the thermal conductive UV glue for GaN high electron mobility transistors.

9. The method for preparing a thermally conductive UV adhesive for a GaN high electron mobility transistor according to claim 8, characterized in that: The chemical plating solution used in the chemical copper plating process in step (2) includes a reducing plating solution, a Cu salt plating solution, and a pH adjusting solution.

10. Application of the thermally conductive UV adhesive according to any one of claims 1 to 7 on GaN high electron mobility transistors, characterized in that: The thermally conductive UV adhesive is used to bond the diamond substrate of the GaN high electron mobility transistor device to the GaN epitaxial material.

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