A high thermal conductivity heat dissipation device

Abstract

The present invention proposes a high thermal conductivity heat dissipation device, which is composed of a high thermal conductivity bottom plate, a surrounding frame and a cover plate from bottom to top; at least one layer of HTCC substrate is provided on the high thermal conductivity bottom plate and in the surrounding frame, and at least one of the upper and lower surfaces of the single-layer HTCC substrate is used to place a heating device; the side of the HTCC substrate connected to the high thermal conductivity bottom plate does not place a heating device. The high thermal conductivity heat dissipation device provided by the present invention uses a large-area HTCC substrate and a diamond aluminum bottom plate to solve the heat dissipation problem of a high heat flux density heating chip of a microwave power module.

Description

Technical Field

[0001] The invention relates to the field of microwave power modules, and in particular to a high thermal conductivity heat dissipation device. Background Art

[0002] Microwave power modules are widely used in military and civilian fields such as radar, electronic countermeasures, and communications. With the development of the third-generation GaN semiconductor materials, the integration and power continue to increase, and the heat generation of microwave power modules has increased exponentially. The heat flux density of X-band power chips has reached 200W / cm2 or even higher, which poses a great challenge to the module's heat dissipation capacity, especially heat conduction.

[0003] At present, in the domestic military or civilian fields, the heat sinks of microwave power module heating chips mostly use second-generation thermal management materials such as tungsten copper and copper-molybdenum copper. For example, the copper-molybdenum copper heat sink material mentioned in the patent CN201310001249.X "Laminar structure heat sink material and preparation method" adopts three-layer composite to realize the preparation of molybdenum copper or tungsten copper heat sink. The copper-molybdenum-copper heat sink material mentioned in the patent CN200910213372.1 "Copper-molybdenum-copper heat sink material and preparation method". The packaging shell is the first to third generation thermal management materials such as Kovar and aluminum silicon, such as the Kovar alloy packaging shell mentioned in the patent CN201810044629.4 "Preparation method of Kovar alloy wall for electronic packaging", and the aluminum silicon shell packaging material mentioned in the patent CN201510812388.X "A preparation method of gradient aluminum silicon electronic packaging material". In some high-end application fields, the fourth generation of heat sink materials such as diamond aluminum and diamond copper are gradually being applied, such as the heat sink material mentioned in patent CN201710434894.9 "A diamond-aluminum composite material used as an electronic packaging material" and the heat sink material mentioned in patent CN201520980982.5 "Diamond copper heat sink material". Although the thermal conductivity of diamond-based composite materials is as high as about 600W / m / K, which is about 3 times that of aluminum, the presence of diamond particles leads to the disadvantages of difficult processing and high cost. Generally, the flat structure can only be achieved by grinding. For the packaging shell of the microwave power module, it is necessary to design the power supply and RF interface in order to install the connection terminal. There must be fine and complex structures such as threads, chamfers, and stepped holes, which can only be completed by machining, thus limiting the application of diamond-based composite materials in the packaging shell. Therefore, there is no report on the application of diamond-based composite materials in the packaging shell.

[0004] In addition, LTCC substrates are widely used inside microwave power modules. As the functions of the substrates expand and the integration level increases, the available area of ​​the power chip heat sink gradually decreases. In high frequency bands such as Ka, the heat sink area is even equivalent to the chip, and the heat expansion effect is not played. Under high thermal conductivity requirements, HTCC (High Temperature co-fired Ceramic) substrates are also gradually being used. For example, the substrate material mentioned in patent CN201811144572.1 "A four-channel microwave T / R component" and the HTCC substrate mentioned in patent CN201520794769.5 "A high-density assembly structure of a TR component" also have the problem of insufficient heat sink expansion area.

[0005] In general, in order to improve the heat dissipation capacity of high-power microwave power modules, it is urgent to solve the technical problems of how to realize the application of diamond-based high thermal conductivity materials as packaging shells and how to improve the heat expansion capacity of heat sinks. Summary of the invention

[0006] The purpose of the present invention is to solve the above problems and propose a high thermal conductivity heat dissipation device, which is composed of a high thermal conductivity bottom plate, a surrounding frame and a cover plate from bottom to top; at least one layer of HTCC substrate is provided on the high thermal conductivity bottom plate and in the surrounding frame, and at least one of the upper and lower surfaces of the single-layer HTCC substrate is used to place a heat generating device; and no heat generating device is placed on the side of the HTCC substrate connected to the high thermal conductivity bottom plate.

[0007] Furthermore, the heat generating device is a chip, and the power of any chip except the bottom chip is not greater than the power of the chip located therebelow.

[0008] Furthermore, the high thermal conductivity base plate is a diamond aluminum composite material, and the difference in thermal expansion coefficient between the HTCC substrate and the high thermal conductivity base plate is greater than or equal to -3ppm / K and less than or equal to 3ppm / K.

[0009] Furthermore, the HTCC substrate is a single layer, and a cavity is provided on the upper surface thereof, the cavity is used to place the chip, the surface of the chip in the cavity is located between the upper and lower surfaces of the HTCC substrate, and the chip is staggered in the vertical direction.

[0010] Furthermore, a plurality of HTCC substrates are arranged in the enclosure, and the HTCC substrates are stacked on a high thermal conductivity bottom plate; except for the chip arranged on the upper surface of the uppermost HTCC substrate, the other chips are arranged through the cavity on the surface of the HTCC substrate, and the surface of the chip in the cavity is located between the upper and lower surfaces of the HTCC substrate, and the chips are staggered in the vertical direction.

[0011] Furthermore, positioning pins are provided on the bottom surface of the surrounding frame, and holes are punched at corresponding positions of the high thermal conductivity bottom plate to cooperate with the positioning pins for positioning.

[0012] Furthermore, the surrounding frame is made of Al 6061, which is generated during the preparation process of the high thermal conductivity base plate, and the cover plate is made of Al4047.

[0013] Furthermore, the surrounding frame uses aluminum AlSi50 and the cover plate uses AlSi27.

[0014] Furthermore, the frame uses TC4 and the cover plate uses TA2.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] (1) The use of a large-area HTCC substrate solves the problem of heat expansion difficulty of the high heat flux density heating chip of the microwave power module;

[0017] (2) The diamond / aluminum composite bottom plate solves the problem of heat conduction temperature rise in the shell of the microwave power module. At the same time, effective secondary heat expansion further reduces the heat flux density and reduces the contact temperature rise between the module and the cold plate.

[0018] (3) By using different types of materials for the base plate, frame and cover plate and composite connections, the engineering problems of microwave power modules directly using high thermal conductivity materials, such as difficult processing, high density and high cost, are solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the overall assembly view of the first embodiment.

[0020] Figure 2 This is an exploded view of the first embodiment.

[0021] Figure 3 This is an assembly view of the surrounding frame and the high thermal conductivity base plate of the first embodiment.

[0022] Figure 4 Schematic diagram of traditional heat transfer method of microwave power module.

[0023] Figure 5 It is a schematic diagram of the heat transfer method of the microwave power module according to the present invention.

[0024] Figure 6 It is a partial schematic diagram of the first embodiment.

[0025] Figure 7 for Figure 6 AA section view.

[0026] The meanings of the symbols in the figure are:

[0027] Cover plate 1, surrounding frame 2, high thermal conductivity base plate 3, upper HTCC substrate 4, lower HTCC substrate 5, low-power chip 6, high-power chip 7. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0029] Various aspects of the present invention are described in this disclosure with reference to the accompanying drawings, in which many illustrative embodiments are shown. The embodiments of the present disclosure are not necessarily intended to include all aspects of the present invention. It should be understood that the various concepts and embodiments introduced above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed by the present invention are not limited to any implementation. In addition, some aspects disclosed by the present invention can be used alone or in any appropriate combination with other aspects disclosed by the present invention.

[0030] Embodiment 1

[0031] The schematic diagram of the high thermal conductivity heat dissipation device proposed by the present invention is as follows Figure 1 , Figure 2 As shown, the device is composed of a high thermal conductivity base plate 3, a surrounding frame 2 and a cover plate 1 from bottom to top. An upper HTCC substrate 4 and a lower HTCC substrate 5 are encapsulated in the device; a low-power chip 6 and a high-power chip 7 are arranged on the HTCC substrate 4 and the lower HTCC substrate 5.

[0032] The high thermal conductivity bottom plate 3 is a diamond aluminum composite material. By adjusting the volume fraction of diamond, the thermal expansion coefficient of the bottom plate is matched with that of the HTCC substrate. Generally, the thermal expansion coefficient of the HTCC substrate is 4-5ppm / K (ppm / K is the temperature coefficient). When the volume fraction of diamond in diamond aluminum reaches more than 70%, the thermal expansion coefficient of the diamond aluminum composite material can reach about 7ppm / K, which meets the requirement that the difference in thermal expansion coefficients of the two-layer welding interface is greater than or equal to -3ppm / K and less than or equal to 3ppm / K. The surface of the high thermal conductivity bottom plate 3 can directly form an aluminum metal layer in a preparation process such as high pressure casting. If a pressure infiltration process is used, it needs to be subsequently ground and then plated with a metal layer, such as titanium plating and then copper plating, so as to meet the requirements of large-area connection with the HTCC substrate by soft soldering. The thickness of the aluminum metal layer or metal plating on one side is controlled at 50um, which is equivalent to the thickness of general gold-tin solder. The total thickness on both sides is about 100um. According to the total thickness of the general base plate of 2mm, the aluminum foil layer accounts for about 5%, which has little effect on the thermal expansion coefficient of the entire base plate, and can ensure the thermal matching of the base plate and the HTCC substrate, as well as the requirements of welding for surface metallization. The high thermal conductivity base plate and the surrounding frame are connected by soft soldering.

[0033] The upper HTCC substrate 4 has a long heat transfer path. Since the upper layer is unobstructed, the upper surface can be surface mounted or welded with a low-power chip 6, or the low-power chip 6 can be welded through the cavity 5-1. Figure 6 and 7 As shown, the surface of the cavity 5-1 is located between the upper and lower surfaces of the HTCC substrate. The lower HTCC substrate 5 has a short heat transfer path and can be welded with high-power chips 7 arranged in an array. Since the upper surface of the lower HTCC substrate 5 needs to be welded with the lower surface of the upper HTCC substrate 4 in a large area, the cavity 5-1 can only be made on the upper surface, and the high-power chip 7 is welded in the cavity 5-1. The height of the chip welded in the cavity 5-1 is lower than the surface of the HTCC substrate 4. The lower HTCC substrate 5 is welded to the high thermal conductivity base plate 3, and no chip is placed on the welding surface. The lower HTCC substrate 5 and the upper HTCC substrate 4 are connected by BGA or large-area soldering. The heat transfer path is (low-power chip 6→upper HTCC substrate 4)→(high-power chip 7→lower HTCC substrate 5)→high thermal conductivity base plate 3. The low-power chip 6 and the high-power chip 7 should be staggered in the vertical direction to form a reasonable heat dissipation path.

[0034] There are many options for the frame 2 and the cover plate 1. If low cost is given priority, Al6061 can be selected for the frame 2, which is produced in the preparation process of the high thermal conductivity base plate 3, such as high-pressure casting or pressure infiltration, to avoid re-plating of the metal layer, and Al4047 can be selected for the cover plate 1; if compatibility with the original aluminum silicon and other packaging shell processes is given priority, aluminum silicon alloy (AlSi50) can be selected for the frame 2, which is welded to the high thermal conductivity base plate 3 after nickel and gold plating, and aluminum silicon alloy (AlSi27) can be selected for the cover plate 1; if high strength and high reliability are considered, titanium alloy (TC4) can be selected for the frame 2, and the connection method is similar to that of aluminum silicon alloy, and titanium alloy (TA2) can be selected for the cover plate 1. The frame 2 and the cover plate 1 are connected by laser hermetic sealing welding process. Figure 3 As shown, when the frame 2 is made of aluminum silicon alloy or titanium alloy, in order to ensure the accurate fixation of the large-sized frame and the high thermal conductivity bottom plate 3 during welding, the bottom surface of the frame 2 adopts a circular or quadrilateral positioning pin 2-1, and the high thermal conductivity bottom plate 3 is punched at the corresponding position for matching positioning. The frame 2 and the high thermal conductivity bottom plate 3 are connected by soft soldering.

[0035] The overall connection process of the device is two-step step welding and one-step sealing welding, specifically:

[0036] First, the high thermal conductivity base plate 3 and the surrounding frame 2 are welded, positioned and matched, and a fixture is used. The highest welding temperature is adopted, and gold-tin solder can be selected. The welding temperature is about 283° C. to form a packaging shell without a cover plate 1.

[0037] Secondly, gold-tin solder or conductive silver paste with a temperature resistance of more than 300°C is used on the HTCC substrate to connect the chip to the HTCC substrate, including the connection between the high-power chip 7 and the lower HTCC substrate 5, and the low-power chip 6 and the upper HTCC substrate 4, to form two single-layer HTCC substrates with heating chips; then, the two single-layer HTCCs with heating chips are stacked and welded to the packaging shell over a large area. Tin-lead solder can be selected, and the welding temperature is about 183°C.

[0038] Finally, the cover plate 1 and the packaging shell are laser hermetic welded to ensure the airtightness requirement when applied to the microwave power module.

[0039] Embodiment 2

[0040] This embodiment is basically the same as the first embodiment, except that a cavity 5-1 is provided on the lower surface of the upper HTCC substrate, a low-power chip 6 is welded in the cavity 5-1, and the surface of the low-power chip 6 is located between the upper and lower surfaces of the HTCC substrate.

[0041] Embodiment 3

[0042] This embodiment is basically the same as the first embodiment, except that the HTCC substrate in this embodiment is a single-layer substrate. A low-power chip 6 is mounted or welded on the upper surface of the single-layer HTCC substrate, and no chip is provided on the side connected to the high thermal conductivity base plate 3.

[0043] The present invention utilizes a large-area HTCC substrate to solve the heat expansion problem of the high heat flux density heating chip of the microwave power module;

[0044] The present invention utilizes a diamond / aluminum composite bottom plate to solve the problem of the heat conduction temperature rise of the shell of the microwave power module, and at the same time effectively expands the heat secondary, further reduces the heat flux density, and reduces the contact temperature rise between the module and the cold plate;

[0045] The present invention solves the engineering use problems of difficult processing, high density and high cost caused by directly using high thermal conductivity materials for microwave power modules by using base plates, surrounding frames and cover plates of different types of materials and composite connections.

[0046] Figure 4 The traditional heat transfer method has a narrow heat transfer path and a large thermal resistance, while the heat transfer method of the third embodiment of the present invention is as follows Figure 5 As shown, the heat transfer path is wide, the heat flux is low, and the thermal resistance is small.

[0047] In summary, the high thermal conductivity heat sink provided by the present invention has a wide effective heat transfer path compared to the traditional molybdenum copper heat sink and aluminum, aluminum silicon or aluminum carbon silicon packaging shell, and can quickly reduce the high heat flux density at the chip to a low heat flux density. The total conduction thermal resistance is small, and a special base plate, frame and cover plate composite structure design is adopted to meet the production and processing requirements such as easy processing, lightweight, economy, and airtightness, which creates a good prerequisite for the subsequent cold plate or radiator for heat exchange.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A high thermal conductivity heat dissipation device, characterized in that: The device is composed of a high thermal conductivity bottom plate (3), a surrounding frame (2) and a cover plate (1) in order from bottom to top; at least one layer of HTCC substrate is provided on the high thermal conductivity bottom plate (3) and in the surrounding frame (2); at least one of the upper and lower surfaces of the single-layer HTCC substrate is used to place a heating device; no heating device is placed on the side of the HTCC substrate connected to the high thermal conductivity bottom plate (3); the heating device is a chip, and the power of any chip except the bottom chip is not greater than the power of the chip located below it; the high thermal conductivity bottom plate (3) is a diamond aluminum composite material, and the difference in thermal expansion coefficient between the HTCC substrate and the high thermal conductivity bottom plate (3) is greater than or equal to -3ppm / K and less than or equal to 3ppm / K.

2. The high thermal conductivity heat sink according to claim 1, characterized in that: The HTCC substrate is a single layer, and a cavity (5-1) is arranged on the upper surface. The cavity (5-1) is used to place a chip, and the surface of the chip in the cavity (5-1) is located between the upper and lower surfaces of the HTCC substrate.

3. The high thermal conductivity heat sink according to claim 1, characterized in that: A plurality of HTCC substrates are arranged in the enclosure (2), and the HTCC substrates are stacked on a high thermal conductivity base plate (3); except for the chip arranged on the upper surface of the uppermost HTCC substrate, the other chips are arranged through a cavity (5-1) on the surface of the HTCC substrate, the surface of the chip in the cavity (5-1) is located between the upper and lower surfaces of the HTCC substrate, and the chips are staggered in the vertical direction.

4. The high thermal conductivity heat sink according to claim 2 or 3, characterized in that: The bottom surface of the surrounding frame (2) is provided with a positioning pin (2-1), and holes are punched at corresponding positions of the high thermal conductivity bottom plate (3) to cooperate with the positioning pin (2-1) for positioning.

5. The high thermal conductivity heat sink according to claim 4, characterized in that: The surrounding frame (2) is made of Al 6061 and is produced during the preparation process of the high thermal conductivity base plate (3), and the cover plate (1) is made of Al 4047.

6. The high thermal conductivity heat sink according to claim 4, characterized in that: The frame (2) is made of aluminum AlSi50, and the cover plate (1) is made of AlSi27.

7. The high thermal conductivity heat sink according to claim 4, characterized in that: The frame (2) uses TC4 and the cover (1) uses TA2.

Images