A metal ceramic tube package for low-frequency high-power devices

Abstract

The present invention provides a metal-ceramic tube package for low-frequency, high-power devices, comprising a rectangular metal heat sink, a ceramic package body, and a power device; a connection portion is provided at each end of the metal heat sink, and a thermal phase change material layer is embedded between the two connection portions; a first heat dissipation portion is provided on the bottom wall of the ceramic package body, and the first heat dissipation portion corresponds to the position of the phase change material layer; the power device is bonded to the inner bottom wall of the ceramic package body and is located directly above the first heat dissipation portion; wherein the first heat dissipation portion is used to conduct the heat emitted by the power device to the thermal phase change material layer, and then transfer the heat to the metal heat sink for heat exchange with the outside world; the area on the metal heat sink between the ceramic package body and the two connection portions is provided with a stress relief portion. The metal-ceramic tube package for low-frequency, high-power devices provided by the present invention can improve the long-term reliability of the power device from two aspects: overcoming mechanical stress problems and heat dissipation problems.

Description

Technical Field

[0001] The present invention belongs to the technical field of tube and shell packaging, and in particular relates to a metal ceramic tube and shell packaging for a low-frequency high-power device. Background Art

[0002] As microwave power devices develop towards higher power, the power chips used in these devices are becoming larger, and as a result, the aspect ratio of the package has also increased. This has led to increasingly serious stress issues in power devices during engineering applications. Currently, the aspect ratio of the package used for high-power devices is close to four to one. At the same time, since adhesive fixation cannot meet long-term use requirements, power device packages are mostly fixed by brazing to ensure long-term sealing performance. However, due to the poor ductility of solder, the tightening stress during the fixing of the package in actual engineering applications can easily cause cracking of the ceramic body of the package due to the tension. In severe cases, it can even damage and burn the power chip. In addition, due to the high heat generation of high-power devices, relying solely on the package itself to dissipate heat to the outside world is not very effective in dissipating heat, which is also a factor that can cause power chips to overheat and burn, affecting their long-term reliability. Summary of the Invention

[0003] The embodiment of the present invention provides a metal ceramic tube package for a low-frequency high-power device, aiming to enhance the mechanical stress release capability and heat dissipation capability of the package tube package, thereby improving the long-term reliability of the power chip.

[0004] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is: to provide a low-frequency, high-power device metal-ceramic tube package, comprising a rectangular metal heat sink, a ceramic package body, and a power device; a connecting portion is provided at each end of the metal heat sink, and a thermal phase change material layer is embedded on the top surface of the metal heat sink between the two connecting portions; the ceramic package body has an airtight cavity, and the peripheral area of the bottom surface of the ceramic package body is seamlessly welded to the top wall area of the metal heat sink located outside the thermal phase change material layer, and a first heat dissipation portion is provided on the bottom wall of the ceramic package body, and the first heat dissipation portion corresponds to the position of the phase change material layer; the power device is encapsulated in the airtight cavity, adhered to the inner bottom wall of the ceramic package body, and located directly above the first heat dissipation portion; wherein the first heat dissipation portion is used to conduct the heat emitted by the power device to the thermal phase change material layer, and then transfer the heat to the metal heat sink for heat exchange with the outside world; the area on the metal heat sink located between the ceramic package body and the two connecting portions is provided with a stress relief portion.

[0005] In one possible implementation, the first heat dissipation portion is a plurality of heat dissipation holes provided on the bottom wall of the ceramic package, a filling groove is provided on the top surface of the metal heat sink directly below the first heat dissipation portion, and the thermal phase change material layer is embedded in the filling groove.

[0006] In some embodiments, multiple heat dissipation holes are distributed in an array along the length and width directions of the metal heat sink, and multiple filling slots are distributed at intervals along the width direction of the metal heat sink. Each filling slot corresponds to a row of heat dissipation holes arranged along the length direction of the metal heat sink, and each filling slot is embedded with a thermal phase change material layer.

[0007] In some embodiments, an air gap is provided between the thermal phase change material layer and the bottom wall of the ceramic package, and a portion of the metal heat sink located between adjacent filling slots is in contact with the bottom wall of the ceramic package.

[0008] In some embodiments, the thermal phase change material layer is a composite phase change material of graphene foam and paraffin.

[0009] In a possible implementation, a second heat dissipation portion extending toward an outer side of a long side wall of the ceramic package is provided on the long side wall.

[0010] Exemplarily, an embedding groove is provided on the outer wall of the long side of the ceramic package, and the second heat dissipation portion is a heat-conducting metal fin with one end inserted into the embedding groove and fixed by welding.

[0011] In some embodiments, the stress relief portion is a through groove extending along the width direction of the metal heat sink, and the ratio of the through groove width to the length of the metal heat sink is 1:40-45; the ratio of the through groove depth to the thickness of the metal heat sink is 1:3.6-4.

[0012] For example, the ceramic package includes a ceramic bottom shell and a cover plate sealed and welded to the mouth of the ceramic bottom shell, and the cover plate and the ceramic bottom shell together form an airtight cavity; wherein, C-shaped grooves are respectively opened on the outer walls on both sides of the ceramic bottom shell near the two connecting parts, and the bottom surface of the cover plate is thinned and fits with the open end wall of the ceramic bottom shell.

[0013] In a possible implementation, the connecting portion is a U-shaped notch opened at an end position of the metal heat sink.

[0014] The beneficial effects of the metal-ceramic tube package for a low-frequency, high-power device provided by the present invention are as follows: compared with the prior art, in the metal-ceramic tube package for a low-frequency, high-power device provided by the present invention, the ceramic package is fixed on a metal heat sink and fixedly connected to the mounting position via two connecting portions located on the outer sides of the two ends of the ceramic package. Since a stress relief portion is provided between the connecting portion and the ceramic package, the mechanical stress generated by the fixed connection between the metal heat sink and the mounting position can be slowly released, thereby preventing the mechanical stress from extending to the ceramic package and the power device encapsulated in the airtight cavity, and preventing the ceramic package and the power device from being broken by stress pulling. At the same time, since the metal heat sink has a thermal phase change material layer, the rapid heat absorption performance of the thermal phase change material can be utilized to quickly absorb the heat dissipated by the power device during operation through the first heat dissipation portion, and then the heat is transferred to the metal heat sink for heat exchange and heat dissipation with the outside world, thereby improving the rapid heat dissipation capability of the ceramic package, preventing the power device from overheating and burning, and improving the long-term reliability of the power device from overcoming both mechanical stress problems and heat dissipation problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of a top view of a metal-ceramic tube package for a low-frequency, high-power device provided by an embodiment of the present invention;

[0016] Figure 2 For the Figure 1 Schematic diagram of the cross-sectional structure along line AA;

[0017] Figure 3 For the Figure 1 Schematic diagram of the cross-sectional structure along line BB;

[0018] Figure 4 For the Figure 1 Schematic diagram of the cross-sectional structure of the CC line;

[0019] Figure 5 for Figure 2 Schematic diagram of the local enlarged structure at D in the middle;

[0020] Figure 6 This is a schematic structural diagram of a metal heat sink used in an embodiment of the present invention.

[0021] In the figure: 100, metal heat sink; 101, connecting part; 102, thermal phase change material layer; 103, stress relief part; 104, filling groove; 200, ceramic package; 201, ceramic bottom shell; 2011, C-shaped groove; 202, cover plate; 203, airtight cavity; 204, first heat dissipation part; 2040, heat dissipation hole; 205, second heat dissipation part; 300, power device; 400, air gap. DETAILED DESCRIPTION

[0022] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0023] Please also refer to Figures 1 to 4 The present invention provides a low-frequency high-power device metal ceramic tube package. The low-frequency high-power device metal ceramic tube package comprises a rectangular metal heat sink 100, a ceramic package body 200, and a power device 300. The metal heat sink 100 has a connection portion 101 at both ends, and a thermal phase change material layer 102 is embedded on the top surface of the metal heat sink 100 between the two connection portions 101. The ceramic package body 200 has an airtight cavity 203. The bottom peripheral area of the ceramic package body 200 is seamlessly welded to the top wall area of the metal heat sink 100 located outside the thermal phase change material layer 102. The bottom wall of the ceramic package body 200 is provided with a heat exchanger. There is a first heat dissipation portion 204, which corresponds to the position of the phase change material layer; the power device 300 is encapsulated in the airtight cavity 203, adhered to the inner bottom wall of the ceramic package body 200, and located directly above the first heat dissipation portion 204; wherein, the first heat dissipation portion 204 is used to conduct the heat emitted by the power device 300 to the thermal phase change material layer 102, and then transfer the heat to the metal heat sink 100 for heat exchange with the outside world; the area on the metal heat sink 100 located between the ceramic package body 200 and the two connecting parts 101 is provided with a stress relief portion 103.

[0024] It should be noted that the metal heat sink 100 adopts a rectangular structure mainly to match the high aspect ratio (length: width ≈ 4:1) of the ceramic package 200 prepared for the size of the power device 300. The rectangular structure specifically refers to that the four corners of the rectangle can have rounded corners or chamfered structures. Of course, it is also possible to directly adopt a square rectangular structure, which is not limited here. It should be understood that when installed and used in actual engineering, the power device 300 should be mounted before the ceramic package 200 is packaged, and the mounted cavity should be airtightly sealed to form an airtight cavity 203. The ceramic package 200 is a commonly used process structure for achieving airtight packaging of the power device 300. Its specific packaging form is not limited or detailed here, and the ceramic package 200 The first heat dissipation portion 204 can specifically be a thermally conductive material embedded in the bottom wall of the ceramic package 200, and the thermally conductive material is used to contact the power device 300 and the thermal phase change material layer 102 respectively to transfer heat. The specific implementation method can be to perforate the bottom wall of the ceramic package 200 and fill it with thermal conductive glue or penetrate a graphene rod, or directly use perforation to dissipate heat to the thermal phase change material layer 102. Of course, it should be emphasized that in order to ensure the airtightness of the package of the power device 300, when the ceramic package 200 and the metal heat sink 100 are connected (brazing), it should be ensured that the bottom peripheral area of the ceramic package 200 and the top wall area of the metal heat sink 100 located outside the thermal phase change material layer 102 are seamlessly welded to ensure the airtightness of the airtight cavity 203.

[0025] The present embodiment provides a metal ceramic tube package for a low-frequency high-power device. Compared with the prior art, the ceramic package is fixed on a metal heat sink 100 and is fixedly connected to the mounting position by two connecting parts 101 located on the outer sides of the two ends of the ceramic package. Since a stress relief part 103 is provided between the connecting part 101 and the ceramic package, the mechanical stress generated by the fixed connection between the metal heat sink 100 and the mounting position can be slowly released, thereby preventing the mechanical stress from extending to the ceramic package and the power device 300 encapsulated in the airtight cavity 203, and avoiding the ceramic package and the power device 300 from being damaged. The power device 300 is pulled and cracked by stress. At the same time, since the metal heat sink 100 has a thermal phase change material layer 102, the rapid heat absorption performance of the thermal phase change material can be utilized to quickly absorb the heat emitted by the power device 300 during operation through the first heat dissipation portion 204. The heat is then transferred to the metal heat sink 100 for heat exchange and heat dissipation with the outside world, thereby improving the rapid heat dissipation capability of the ceramic package and preventing the power device 300 from overheating and burning. The long-term reliability of the power device 300 is improved by overcoming both mechanical stress problems and heat dissipation problems.

[0026] In some embodiments, see Figure 4The first heat dissipation portion 204 comprises a plurality of heat dissipation holes 2040 formed on the bottom wall of the ceramic package 200. A filling groove 104 is formed on the top surface of the metal heat sink 100, directly below the first heat dissipation portion 204. The thermal phase change material layer 102 is embedded within the filling groove 104. Each heat dissipation hole 2040 serves as a heat absorption channel for the thermal phase change material layer 102 to absorb heat from the power device 300. Compared to heat exchange using only contact heat transfer, this method can further increase the speed at which heat is transferred from the power device 300 to the thermal phase change material layer 102, thereby improving heat dissipation efficiency.

[0027] As a specific distribution method of the plurality of heat dissipation holes 2040, please combine Figure 2 、 Figure 4 and Figure 6 The plurality of heat dissipation holes 2040 are distributed in an array along the length and width directions of the metal heat sink 100. A plurality of filling slots 104 are distributed at intervals along the width direction of the metal heat sink 100. Each filling slot 104 corresponds to a row of heat dissipation holes 2040 arranged along the length direction of the metal heat sink 100, and each filling slot 104 is embedded with a thermal phase change material layer 102. While ensuring the structural strength of the ceramic package 200 itself, as many heat dissipation holes 2040 as possible are opened. At the same time, by arranging the heat dissipation holes 2040 in an array distribution manner, it is possible to provide a thermal phase change material layer 102 corresponding to each row of heat dissipation holes 2040, thereby avoiding the filling groove 104 being opened with an excessive width, thereby avoiding affecting the stiffness of the metal heat sink 100 between the two stress relief portions 103 (the metal body between adjacent filling grooves 104 can serve as a stress beam of the metal heat sink 100 to improve the deformation resistance of the metal heat sink 100 in the long axis direction). This ensures that after the two end connection portions 101 of the metal heat sink 100 are fixedly connected to the installation position, the tightening mechanical stress is released preferentially on the stress relief portions 103, and the problem of deformation of the metal heat sink 100 at the connection position with the ceramic package 200 due to insufficient stiffness will not occur, thereby pulling the ceramic package 200 or the power device 300.

[0028] For some possible implementations, see Figure 2 and Figure 5An air gap 400 is defined between the thermal phase change material layer 102 and the bottom wall of the ceramic package 200, and the portion of the metal heat sink 100 located between adjacent filling slots 104 is in contact with the bottom wall of the ceramic package 200. Providing the air gap 400 prevents direct contact between the first heat dissipation portion 204 (primarily referring to the bottom wall of the ceramic package 200 in the region of the first heat dissipation portion 204) and the thermal phase change material layer 102, thereby preventing heat from being transferred from the thermal phase change material layer 102 to the first heat dissipation portion 204 and affecting the heat dissipation efficiency of the power device 300. Furthermore, by utilizing the portion of the metal heat sink 100 located between adjacent filling slots 104 to be in contact with and supported on the bottom wall of the ceramic package 200, the contact support area between the ceramic package 200 and the metal heat sink 100 is increased, thereby improving connection reliability.

[0029] Specifically, the thermal phase change material layer 102 is a composite phase change material composed of graphene foam and paraffin. The thermal phase change material layer 102 utilizes graphene foam as its skeleton structure and utilizes a liquid-phase infiltration method to absorb paraffin to form the composite phase change material. (When heated, paraffin changes from a solid phase to a liquid phase. In addition to its thermal conductivity, the graphene foam prevents the liquid phase paraffin from flowing freely, ensuring the overall morphological stability of the thermal phase change material layer 102.) Its thermal conductivity can reach 5.5 to 6 W / m·K. When heat from the power device 300 is transferred to the thermal phase change material layer 102 through the heat dissipation holes 2040, the thermal phase change material layer 102 undergoes a phase change when its temperature exceeds its phase transition temperature, thereby absorbing a large amount of heat. Because the thermal phase change material layer 102 is in direct contact with the metal heat sink 100, its ultra-high thermal conductivity allows it to quickly transfer the high temperature to the metal heat sink 100, allowing heat exchange and dissipation with the outside world through the metal heat sink 100, resulting in high heat dissipation efficiency.

[0030] In addition, in order to prevent the thermal phase change material layer 102 from entering the airtight cavity 203 through the heat dissipation hole 2040 after the endothermic phase change (solid phase to liquid phase), a graphene film is attached to the surface of the thermal phase change material layer 102, which can prevent it from flowing into the airtight cavity 203 after the endothermic phase change without affecting its rapid heat absorption performance, thereby improving stability.

[0031] In some embodiments, see Figure 1 and Figure 4The long sidewalls of the ceramic package 200 are provided with a second heat dissipation portion 205 extending outward thereof. Optionally, in this embodiment, the specific structure of the second heat dissipation portion 205 is as follows: a mounting groove is provided on the long side outer wall of the ceramic package 200, and the second heat dissipation portion 205 is a heat-conducting metal fin with one end inserted into the mounting groove and welded in place. Because the heat dissipated by the power device 300 causes the interior of the airtight cavity 203 to heat up, thereby causing the ceramic package 200 to heat up, the second heat dissipation portion 205 is provided here, and the large area and small thickness of the metal fin are utilized to achieve rapid heat exchange with the outside world, thereby improving the heat dissipation efficiency of the ceramic package 200.

[0032] It should be noted that, in this embodiment, please refer to Figure 1 、 Figure 2 and Figure 6 The stress relief portion 103 is a through groove extending along the width direction of the metal heat sink 100. The ratio of the groove width of the through groove to the length of the metal heat sink 100 is 1:40-45; the ratio of the groove depth of the through groove to the thickness of the metal heat sink 100 is 1:3.6-4. It should be understood that the stress relief portion 103 is a structural form with the purpose of mechanical stress release or blocking stress transmission. Specifically, it can be one or more stress relief grooves extending along the width direction of the metal heat sink 100. After the metal heat sink 100 is grooved, the stiffness of the metal heat sink 100 is reduced at the grooved position to improve its bending ductility, thereby releasing stress and reducing the amount of mechanical stress generated by the fastening connection transferred to the ceramic package 200. Alternatively, multiple short stress relief grooves spaced apart along the width direction of the metal heat sink 100 can also be equivalent to improving the bending ductility of the grooved position and improving the mechanical stress release performance. It should be noted that no matter which method is used, In the embodiment of the present invention, the stress relief portion 103 should be located at the position on the metal heat sink 100 where the structural strength is the lowest. In other words, the mechanical stress generated by the fastening force on the metal heat sink 100 causes the metal heat sink 100 to expand and deform at this position to release the stress, thereby blocking the mechanical stress from being transmitted to the connection between the ceramic package 200 and the metal heat sink 100, thereby eliminating or reducing the stress pulling effect on the ceramic package 200. The width and depth of the through-slot are determined based on the aspect ratio of the metal heat sink 100 through optimization simulation tests. They can effectively achieve the slow release of mechanical connection stress without affecting the RF (Radio Frequency) performance of the power device 300, thereby avoiding cracking of the ceramic package 200 and improving the long-term reliability of the power device 300.

[0033] Of course, in order to avoid fracture at the through slot position, the two bottom corners of the through slot and the slot opening corners outside the ceramic package 200 are all set to rounded structures to avoid stress concentration at the corners of the through slot.

[0034] Figure 2 The figure shows a specific embodiment of a ceramic package 200, which includes a ceramic bottom shell 201 and a cover plate 202 sealed and welded to the mouth of the ceramic bottom shell 201. The cover plate 202 and the ceramic bottom shell 201 together form an airtight cavity 203. Figure 5 C-shaped grooves 2011 are respectively provided on the outer walls of the ceramic bottom shell 201 near the two connecting portions 101. The bottom periphery of the cover plate 202 is thinned and aligned with the open end wall of the ceramic bottom shell 201. Before the cover plate 202 and the ceramic bottom shell 201 are hermetically sealed, the power device 300 is mounted on the inner bottom wall of the ceramic bottom shell 201 (directly above the first heat dissipation portion 204). The specific hermetic sealing method can be parallel seam welding or brazing. Due to the difference in expansion coefficients between the ceramic bottom shell 201 and the cover plate 202 after welding, when the power device 300 generates heat and causes temperature changes on the ceramic bottom shell 201 and the cover plate 202, the reliability of the airtight connection may be affected due to thermal stress. Here, by providing the C-shaped grooves 2011 and thinning the surface, the contact area between the opening end wall of the ceramic bottom shell 201 and the edge of the cover plate 202 can be increased, eliminating the problem of cracking and air leakage at the connection position caused by thermal mismatch, and improving long-term reliability.

[0035] For example, see Figure 1 and Figure 6 The connection portion 101 is a U-shaped notch formed at the end of the metal heat sink 100. It should be noted that the function of the connection portion 101 is to reliably connect the metal heat sink 100 to the mounting location. Its specific structure can be a hole or slot, connected to the mounting location via fasteners, or it can be directly connected to the mounting location by welding the outer portions of the ceramic package 200 at both ends. The U-shaped notch structure chosen as the connection portion 101 allows for fine-tuning of the mounting location using the length of the U-shaped notch, while also eliminating the effects of machining errors on the mounting connection and reducing mechanical stress.

[0036] 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 and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A metal ceramic tube package for a low-frequency high-power device, characterized in that: include: A metal heat sink, which is rectangular in shape, has connecting parts at both ends, and a thermal phase change material layer is embedded on the top surface of the metal heat sink between the two connecting parts; A ceramic package having an airtight cavity, wherein a peripheral area of a bottom surface of the ceramic package is seamlessly welded to a top wall area of the metal heat sink located outside the thermal phase change material layer, and a first heat dissipation portion is provided on the bottom wall of the ceramic package, the first heat dissipation portion corresponding to the position of the thermal phase change material layer; A power device is packaged in the airtight cavity, adhered to the inner bottom wall of the ceramic package, and located directly above the first heat dissipation portion; The first heat dissipation portion is used to conduct the heat emitted by the power device to the thermal phase change material layer, and then transfer the heat to the metal heat sink for heat exchange with the outside world; the metal heat sink is provided with a stress relief portion in the area between the ceramic package and the two connecting portions; A second heat dissipation portion extending toward the outside of the ceramic package and used only for heat dissipation is provided on the long side wall of the ceramic package, and a terminal for electrical connection is provided on the long side wall of the ceramic package, and the terminal is located below the second heat dissipation portion; An embedding groove is provided on the outer wall of the long side of the ceramic package, and the second heat dissipation portion is a heat-conducting metal fin with one end inserted into the embedding groove and fixed by welding; The stress relief portion is a through groove extending along the width direction of the metal heat sink, and the ratio of the groove width of the through groove to the length of the metal heat sink is 1:40-45; the ratio of the groove depth of the through groove to the thickness of the metal heat sink is 1:3.6-4.

2. The low-frequency high-power device metal-ceramic package according to claim 1, characterized in that: The first heat dissipation portion is a plurality of heat dissipation holes provided on the bottom wall of the ceramic package. The top surface of the metal heat sink is provided with a filling groove directly below the first heat dissipation portion, and the thermal phase change material layer is embedded in the filling groove.

3. The low-frequency high-power device metal-ceramic package according to claim 2, characterized in that: The plurality of heat dissipation holes are distributed in an array along the length and width directions of the metal heat sink, and the plurality of filling slots are spaced apart along the width direction of the metal heat sink. Each of the filling slots corresponds to a row of heat dissipation holes arranged along the length direction of the metal heat sink, and each of the filling slots is embedded with the thermal phase change material layer.

4. A low-frequency high-power device metal-ceramic package as claimed in claim 3, characterized in that: An air gap is provided between the thermal phase change material layer and the bottom wall of the ceramic package, and a portion of the metal heat sink located between adjacent filling slots is in contact with the bottom wall of the ceramic package.

5. The low-frequency high-power device metal-ceramic package according to claim 2, characterized in that: The thermal phase change material layer is a composite phase change material of graphene foam and paraffin.

6. The low-frequency high-power device metal-ceramic package according to claim 1, characterized in that: The ceramic package includes a ceramic bottom shell and a cover plate sealed and welded to the opening of the ceramic bottom shell, and the cover plate and the ceramic bottom shell together form the airtight cavity; wherein, the outer walls of the ceramic bottom shell on both sides near the two connecting parts are respectively provided with C-shaped grooves, and the bottom surface of the cover plate is thinned and fits with the open end wall of the ceramic bottom shell.

7. A low-frequency high-power device metal-ceramic package according to any one of claims 1 to 6, characterized in that: The connecting portion is a U-shaped notch opened at the end of the metal heat sink.

Images