A composite heat sink based on composite diamond and aluminum nitride substrate and a method of manufacture

Abstract

A composite heat sink based on composite diamond and aluminum nitride substrates and its preparation method are disclosed. The composite heat sink is characterized by being formed by bonding or mechanically connecting a bottom aluminum nitride heat sink (1) and an upper composite diamond / pure diamond heat sink (2). The area of ​​the upper composite diamond / pure diamond heat sink (2) is smaller than that of the bottom aluminum nitride heat sink (1), and the thickness of the upper composite diamond / pure diamond heat sink (2) is not less than twice the thickness of the bottom aluminum nitride heat sink (1). This invention maintains the power intensity of the customer's chip while ensuring overall insulation performance and heat dissipation, and guarantees basic conductivity in some areas, thus reducing costs and increasing efficiency.

Description

Technical Field

[0001] This invention relates to a semiconductor technology, particularly a chip heat dissipation technology, specifically a composite heat sink based on composite diamond and aluminum nitride substrates and its preparation method. Background Technology

[0002] Currently, high-power-density chips generate a lot of heat per unit area, requiring timely heat dissipation through a layer-by-layer transfer to the outside of the electronic device. Heat sinks (micro-heat sinks) are micro-electronic components directly connected to the chip, used to dissipate heat. They are typically made of AlN or diamond substrates with a thickness of 0.1-0.8 mm and a size slightly larger than the chip being connected; their surfaces are coated with various metals and solders required by the customer. When using diamond heat sink substrates, the thermal conductivity of diamond can generally reach over 600 W / mK, making it a key type of heat sink substrate to be developed in the coming years.

[0003] The unit price of existing diamond-based heat sinks is much higher than that of AlN, and the higher the insulation performance (the insulation range of different qualities of diamond is from 10⁵ to 10¹⁵), the higher the unit price of diamond. This remains an obstacle to the large-scale adoption of diamond by laser chip customers, especially in high-frequency laser applications for optical communication (where higher insulation performance is required). While AlN's thermal conductivity (greater than 260 W / mK) is not as high as that of diamond, it is more affordable and has better insulation performance.

[0004] Composite diamond is a material made by mixing pure diamond with metallic copper particles (or aluminum or magnesium, etc.). Compared with pure diamond, although its thermal conductivity is slightly lower, it is cheaper, can conduct electricity, and its coefficient of thermal expansion is more favorable for the chip being dissipated.

[0005] However, to the applicant's knowledge, there is currently no product available for users that organically combines composite diamond with aluminum nitride as a heat sink. Summary of the Invention

[0006] The purpose of this invention is to address the problems of high cost and chip damage caused by inconsistent thermal expansion coefficients of existing single diamond heat sinks, and the low thermal conductivity of single aluminum nitride which makes it difficult to meet the heat dissipation requirements of chips. The invention designs a composite heat sink based on composite diamond and aluminum nitride substrates that combines the characteristics of both and can significantly reduce manufacturing costs. The invention also provides a method for its preparation.

[0007] One of the technical solutions of this invention is:

[0008] A composite heat sink based on composite diamond and aluminum nitride substrates is characterized in that it is formed by bonding or mechanically connecting a bottom aluminum nitride heat sink 1 and an upper composite diamond / pure diamond heat sink 2, wherein the area of ​​the upper composite diamond / pure diamond heat sink 2 is smaller than the area of ​​the bottom aluminum nitride heat sink 1, and the thickness of the upper composite diamond / pure diamond heat sink 2 is not less than twice the thickness of the bottom aluminum nitride heat sink 1.

[0009] The thickness of the bonding layer is no more than 0.05 mm.

[0010] The thickness of the bonding layer is 0.02 mm.

[0011] The diamond content in the composite diamond does not exceed 90%, with the remainder being added single or combined metal materials.

[0012] The second technical solution of the present invention is:

[0013] A method for preparing a composite heat sink based on composite diamond and aluminum nitride substrate, characterized by comprising the following steps:

[0014] First, according to the product design requirements, composite diamond / pure diamond sheets and AlN sheets that can meet the performance requirements are cut as substrates.

[0015] Secondly, a copper layer of 8-10 μm or a gold layer of 0.8-1 μm thickness is sputtered or vapor-deposited on the lower surface of the composite diamond / pure diamond substrate and the upper surface of the AlN substrate.

[0016] Finally, by instantaneously applying a temperature of 50-100℃ and a pressure of 100-110MPa, van der Waals forces are generated between the copper or gold layers, enabling the composite diamond / pure diamond substrate and the AlN substrate to be stably bonded.

[0017] The third technical solution of the present invention is:

[0018] A method for preparing a composite heat sink based on composite diamond and aluminum nitride substrate, characterized by comprising the following steps:

[0019] First, according to the product design requirements, composite diamond / pure diamond sheets and AlN sheets that can meet the performance requirements are cut as substrates.

[0020] Secondly, a gold layer with a thickness of 0.8-1μm is sputtered or vapor-deposited on the lower surface of the composite diamond or diamond substrate, and a gold-tin solder layer with a thickness of 4-5μm is applied to the upper surface of the AlN substrate corresponding to the area of ​​the diamond substrate.

[0021] Finally, gold and tin are melted by applying a temperature of 50-100℃ and a pressure of 100-110MPa, and after cooling, the composite diamond / pure diamond substrate and the AlN substrate are bonded together.

[0022] The fourth technical solution of the present invention is:

[0023] A method for preparing a composite heat sink based on composite diamond and aluminum nitride substrate, characterized by comprising the following steps:

[0024] First, according to the product design requirements, composite diamond / pure diamond sheets and AlN sheets that can meet the performance requirements are cut as substrates.

[0025] Secondly, a metal layer, solder, or solder sheet is sputtered or vapor-deposited in the area of ​​the AlN substrate where no composite diamond / pure diamond sheet is mounted.

[0026] Third, one end of the micro spring is pressed by an auxiliary welding fixture, and the micro spring and the auxiliary welding fixture are simultaneously hot-pressed and fixed on the area of ​​the AlN substrate where no composite diamond / pure diamond sheet is installed. The other end of the micro spring is pressed on the composite diamond / pure diamond sheet or directly on the chip (3) placed on the composite diamond / pure diamond sheet, thereby realizing the mechanical fixation of the composite diamond / pure diamond sheet and the AlN sheet or the fixation of the chip.

[0027] The miniature spring described is a miniature spring with memory function.

[0028] The fifth technical solution of the present invention is:

[0029] A method for preparing a composite heat sink based on composite diamond and aluminum nitride substrate, characterized by comprising the following steps:

[0030] First, according to the product design requirements, composite diamond / pure diamond sheets and AlN sheets that can meet the performance requirements are cut as substrates.

[0031] Secondly, at least two mounting holes are machined in the area of ​​the AlN substrate where composite diamond / pure diamond sheets are not installed. During pre-installation, the lower end of the shape memory spring is directly inserted into the mounting hole on the side of the AlN heat sink from top to bottom. Through the size design of the spring and the temperature control of the process, during the period when the shape memory spring returns to the closed state after bending deformation, the deformation of its lower end makes the change between the shape memory spring and the mounting hole gradually become a local interference fit. Thus, the entire spring is held in the hole by its own material elasticity, eliminating the need for auxiliary welding fixtures, but requiring the thickness of the AlN sheet to be not less than 0.8mm.

[0032] The beneficial effects of this invention are:

[0033] This invention fully utilizes the characteristics of two different substrates, using both composite diamond and AlN as heat sink materials, ensuring both reasonable unit price and meeting increasingly demanding heat dissipation performance. Through a suitable bonding method, composite diamond can be used as the heat sink substrate near the chip's heat-generating area, while AlN can be used as the heat sink substrate connecting to the packaging base.

[0034] This invention can maintain the power intensity of the customer's chip, ensure the overall insulation performance and heat dissipation effect, and ensure basic conductivity in some areas, thereby reducing costs and increasing efficiency. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the heat sink structure of the present invention.

[0036] Figure 2 This is a schematic diagram of the high-heat laser mounted on the heat sink of this invention.

[0037] Figure 3 This is a schematic diagram of the installation of the present invention on the base heat sink.

[0038] Figure 4 This is a schematic diagram of a structure that uses micro-springs to combine a composite diamond heat sink with an aluminum nitride heat sink.

[0039] Figure 5 This is a schematic diagram of a structure that combines a composite diamond heat sink with an aluminum nitride heat sink using a shape memory alloy spring.

[0040] Figure 6 These are schematic diagrams showing the shape memory spring in its pre-installed state (left view) and its heat-recovered state (right view).

[0041] Figure 7 This is a three-dimensional exploded view of the shape memory spring and aluminum nitride heat sink of the present invention using a plug-in connection structure.

[0042] Figure 8 The diagram shows the pre-installed state (right figure) and the closed, chip-locked state of the shape memory spring when the shape memory spring and the aluminum nitride heat sink are connected by a plug-in structure.

[0043] Figure 9 yes Figure 8 A sectional view.

[0044] Figure 10 This is a thermal simulation effect diagram of the present invention. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0046] Example 1.

[0047] like Figure 1-3 As shown.

[0048] A composite heat sink based on a composite diamond and aluminum nitride substrate is formed by bonding an aluminum nitride heat sink 1 at the bottom and a composite diamond heat sink 2 at the top. Figure 1 As shown, chip 3 can be fixed to the upper composite diamond surface by welding or mechanical connection, such as... Figure 2 As shown. The heat sink 4 serves as the base for heat dissipation, as... Figure 3 As shown, the area of ​​the composite diamond heat sink 2 is smaller than that of the bottom aluminum nitride heat sink 1, and the thickness of the upper composite diamond / pure diamond heat sink 2 is not less than twice the thickness of the bottom aluminum nitride heat sink 1. The thickness of the bonding layer is not more than 0.05 mm. The diamond content in the composite diamond is not more than 90%, and the remainder is added single or combined metal materials. The diamond content in the composite diamond should be conventionally selected based on factors such as cost, coefficient of thermal expansion, and thermal conductivity. The specific preparation method includes the following steps:

[0049] First, composite diamond sheets and AlN sheets that meet the performance requirements are cut as substrates according to the product design requirements;

[0050] Secondly, a copper layer of 8-10 μm or a gold layer of 0.8-1 μm thickness is sputtered or vapor-deposited on the lower surface of the composite diamond / pure diamond substrate and the upper surface of the AlN substrate.

[0051] Finally, by instantaneously applying a temperature of 50-100℃ and a pressure of 100-110MPa, van der Waals forces are generated between the copper or gold layers, enabling the composite diamond substrate and the AlN substrate to be stably bonded together.

[0052] Example 2.

[0053] A composite heat sink based on composite diamond and aluminum nitride substrate is formed by bonding an aluminum nitride heat sink 1 at the bottom and a composite diamond heat sink 2 at the top, and is prepared by the following steps:

[0054] First, composite diamond sheets and AlN sheets that meet the performance requirements are cut as substrates according to the product design requirements;

[0055] Secondly, a gold layer with a thickness of 0.8-1μm is sputtered or vapor-deposited on the lower surface of the composite diamond and diamond substrate, and a gold-tin solder layer with a thickness of 4-5μm is applied to the upper surface of the AlN substrate in the area corresponding to the composite diamond substrate.

[0056] Finally, gold and tin are melted by applying a temperature of 50-100℃ and a pressure of 100-110MPa, and after cooling, the composite diamond substrate and AlN substrate are bonded together.

[0057] Example 3.

[0058] like Figure 4 As shown.

[0059] A composite heat sink based on composite diamond and aluminum nitride substrate, which is mechanically connected to an aluminum nitride heat sink 1 at the bottom and a composite diamond heat sink 2 at the top, and is prepared by the following steps:

[0060] First, according to the product design requirements, composite diamond / pure diamond sheets and AlN sheets that can meet the performance requirements are cut as substrates.

[0061] Secondly, a metal layer, solder, or solder sheet is sputtered or vapor-deposited in the area of ​​the AlN substrate where no composite diamond / pure diamond sheet is mounted.

[0062] Third, the auxiliary welding fixture 5 is used to press one end of the micro spring 6, and the micro spring 6 and the auxiliary welding fixture 5 are simultaneously hot-pressed and fixed to the area of ​​the AlN substrate where the composite diamond sheet is not installed. The other end of the micro spring is pressed on the composite diamond / pure diamond sheet 2 or directly on the chip 3 placed on the composite diamond sheet, thereby achieving mechanical fixation of the composite diamond sheet and the AlN sheet or fixation of the chip.

[0063] Example 4.

[0064] like Figure 5 , 6 As shown.

[0065] A composite heat sink based on composite diamond and aluminum nitride substrate, which is mechanically connected to an aluminum nitride heat sink 1 at the bottom and a composite diamond heat sink 2 at the top, and is prepared by the following steps:

[0066] First, according to the product design requirements, composite diamond / pure diamond sheets and AlN sheets that can meet the performance requirements are cut as substrates.

[0067] Secondly, a metal layer, solder, or solder sheet is sputtered or vapor-deposited in the area of ​​the AlN substrate where the composite diamond / pure diamond sheet 2 is not mounted.

[0068] Third, the auxiliary welding fixture 5 is used to press one end of the micro spring 6 with memory function, and the micro spring 6 with memory function and the auxiliary welding fixture 5 are simultaneously hot-pressed and fixed to the area of ​​the AlN substrate where no composite diamond / pure diamond sheet is installed. The other end of the micro spring 6 is pressed on the composite diamond 2 or directly on the chip 3 placed on the composite diamond sheet, thereby realizing the mechanical fixation of the composite diamond sheet and the AlN sheet or the fixation of the chip.

[0069] Example 5.

[0070] like Figure 7 , 8 As shown in Figures 9 and 9.

[0071] A composite heat sink based on composite diamond and aluminum nitride substrate, which is mechanically connected to an aluminum nitride heat sink 1 at the bottom and a composite diamond heat sink 2 at the top, and is prepared by the following steps:

[0072] First, according to the product design requirements, composite diamond / pure diamond sheets and AlN sheets that can meet the performance requirements are cut as substrates.

[0073] Secondly, at least two mounting holes 7 are machined in the area of ​​the AlN substrate where composite diamond / pure diamond sheets are not mounted, such as... Figure 7 As shown; during pre-installation, insert the lower end of the shape memory spring directly into the mounting hole on the side of the AlN heat sink from top to bottom, as shown. Figure 8 Through the design of spring dimensions and temperature control during the manufacturing process, during the period when the shape memory spring returns to its closed state after bending deformation, the deformation at its lower end gradually causes the change between the shape memory spring and the mounting hole to become a local interference fit, so that the entire spring is held in the hole by its own material elasticity. Figure 9 This eliminates the need for auxiliary welding fixtures, but requires the AlN sheet thickness to be no less than 0.8mm.

[0074] The thermal simulation effects of the heat sinks in Examples 1 to 5 are as follows: Figure 10 As shown. Thermal simulation plays a crucial role in various applications. Ensuring thermal expansion and contraction, as well as insulation performance, are also key considerations for heat dissipation in laser chip packaging. In composite heat sinks, minimizing the size of the composite diamond heat sink relative to the area of ​​the AlN heat sink, and the selection of combinations of metal layers, solder, and bonding pads are also critical to overall cost. Temperature control during the manufacturing process is also extremely important, determining the final reliability and lifespan of the product.

[0075] All parts not covered in this invention are the same as or can be implemented using existing technologies.

Claims

1. A composite heat sink based on composite diamond and aluminum nitride substrate, characterized in that: It is formed by bonding or mechanically connecting the bottom aluminum nitride heat sink (1) and the top composite diamond / pure diamond heat sink (2). The area of ​​the top composite diamond / pure diamond heat sink (2) is smaller than the area of ​​the bottom aluminum nitride heat sink (1), and the thickness of the top composite diamond / pure diamond heat sink (2) is not less than twice the thickness of the bottom aluminum nitride heat sink (1).

2. The composite heat sink according to claim 1, characterized in that: The thickness of the bonding layer is no more than 0.05 mm.

3. The composite heat sink according to claim 1, characterized in that: The thickness of the bonding layer is 0.02 mm.

4. The composite heat sink according to claim 1, characterized in that: The diamond content in the composite diamond does not exceed 90%, and the remainder consists of single or combined metal materials.

5. A method for preparing a composite heat sink based on composite diamond and aluminum nitride substrate, characterized in that: Includes the following steps: First, according to the product design requirements, composite diamond / pure diamond sheets and AlN sheets that can meet the performance requirements are cut as substrates. Secondly, a copper layer of 8-10 μm or a gold layer of 0.8-1 μm thickness is sputtered or vapor-deposited on the lower surface of the composite diamond / pure diamond substrate and the upper surface of the AlN substrate. Finally, by instantaneously applying a temperature of 50-100℃ and a pressure of 100-110MPa, van der Waals forces are generated between the copper or gold layers, enabling the composite diamond / pure diamond substrate and the AlN substrate to be stably bonded.

6. A method for preparing a composite heat sink based on composite diamond and aluminum nitride substrate, characterized in that: Includes the following steps: First, according to the product design requirements, composite diamond / pure diamond sheets and AlN sheets that can meet the performance requirements are cut as substrates. Secondly, a gold layer with a thickness of 0.8-1μm is sputtered or vapor-deposited on the lower surface of the composite diamond or diamond substrate, and a gold-tin solder layer with a thickness of 4-5μm is applied to the upper surface of the AlN substrate corresponding to the area of ​​the diamond substrate. Finally, gold and tin are melted by applying a temperature of 50-100℃ and a pressure of 100-110MPa, and after cooling, the composite diamond / pure diamond substrate and the AlN substrate are bonded together.

7. A method for preparing a composite heat sink based on composite diamond and aluminum nitride substrate, characterized in that: Includes the following steps: First, according to the product design requirements, composite diamond / pure diamond sheets and AlN sheets that can meet the performance requirements are cut as substrates. Secondly, a metal layer, solder, or solder sheet is sputtered or vapor-deposited in the area of ​​the AlN substrate where no composite diamond / pure diamond sheet is mounted. Third, one end of the micro spring is pressed by an auxiliary welding fixture, and the micro spring and the auxiliary welding fixture are simultaneously hot-pressed and fixed on the area of ​​the AlN substrate where no composite diamond / pure diamond sheet is installed. The other end of the micro spring is pressed on the composite diamond / pure diamond sheet or directly on the chip (3) placed on the composite diamond / pure diamond sheet, thereby realizing the mechanical fixation of the composite diamond / pure diamond sheet and the AlN sheet or the fixation of the chip.

8. The method for preparing a composite heat sink based on a composite diamond and aluminum nitride substrate according to claim 7, characterized in that: The miniature spring described is a miniature spring with memory function.

9. A method for preparing a composite heat sink based on composite diamond and aluminum nitride substrate, characterized in that: Includes the following steps: First, according to the product design requirements, composite diamond / pure diamond sheets and AlN sheets that can meet the performance requirements are cut as substrates. Secondly, at least two mounting holes are machined in the area of ​​the AlN substrate where composite diamond / pure diamond sheets are not installed. During pre-installation, the lower end of the shape memory spring is directly inserted into the mounting hole on the side of the AlN heat sink from top to bottom. Through the size design of the spring and the temperature control of the process, during the period when the shape memory spring returns to the closed state after bending deformation, the deformation of its lower end makes the change between the shape memory spring and the mounting hole gradually become a local interference fit. Thus, the entire spring is held in the hole by its own material elasticity, eliminating the need for auxiliary welding fixtures, but requiring the thickness of the AlN sheet to be not less than 0.8mm.

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