GaN device double-sided heat dissipation structure based on flexible plate bottom filling
By using a double-sided heat dissipation structure filled at the bottom of a flexible board, combined with nano-metal sintering technology and thermal interface materials, the problems of single heat transfer path and poor heat dissipation capacity of GaN devices are solved, achieving high integration, hermetically sealed packaging and excellent thermal conductivity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING SATELLITE MFG FACTORY
- Filing Date
- 2025-12-09
- Publication Date
- 2026-04-21
AI Technical Summary
GaN devices suffer from problems such as a single heat transfer path, high thermal resistance, large package size, and poor heat dissipation in traditional packaging structures. In particular, the welding area is limited in flip-chip bonding and the thermal resistance of tin-based solder is high, resulting in a greater risk of electromigration and electrochemical migration of nano-silver materials.
A double-sided heat dissipation structure with flexible board bottom filling is adopted. The electrical interconnection between GaN device and ceramic substrate is achieved through nano-metal material sintering process. A thermal interface material is set between GaN device and cover plate. Combined with flip-chip welding and parallel seam welding process, a double-sided heat dissipation path is formed. Flexible insulating copper-clad laminate is used to improve insulation and reduce mechanical stress.
This technology achieves highly integrated packaging of GaN devices, improves thermal conductivity and high-temperature performance, avoids electromigration problems, achieves hermetically sealed packaging and double-sided heat dissipation, and reduces the overall thermal stress of the devices.
Smart Images
Figure CN121908883A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor packaging technology, and in particular to a double-sided heat dissipation structure for GaN devices based on bottom filling of a flexible plate. Background Technology
[0002] In GaN transistors, a two-dimensional electron gas with high electron mobility is confined within the heterojunction interface formed by AlGaN and GaN, resulting in a very high heat flux density and a significant self-heating effect in GaN HEMT devices. Therefore, a well-designed packaging structure is necessary to effectively dissipate heat from the heat source.
[0003] In traditional packaging structures, heat transfer typically occurs through the chip interconnect material, substrate, thermally conductive adhesive, and heat sink. However, this single heat transfer path still results in a relatively high junction thermal resistance, necessitating the development of more heat transfer paths. For GaN devices, traditional front-side packaging uses wire bonding for electrical connection. However, wire bonding increases both stray inductance and overall device size. Therefore, novel GaN device packaging employs flip-chip bonding. However, flip-chip bonding limits the bonding area, and the tin-based solder used inherently has high thermal resistance, resulting in poor overall heat dissipation.
[0004] The sintering process of nanomaterials offers excellent advantages in low-temperature bonding and high-temperature operation, and also possesses superior electrical and thermal conductivity, which can solve the high thermal conductivity interconnection problem of GaN devices. Among them, nanosilver is the most commonly used nanomaterial for sintering, but the electromigration and electrochemical migration of silver ions pose a significant risk to flip-chip bonding devices with high lead density. Summary of the Invention
[0005] This invention provides a double-sided heat dissipation structure for GaN devices based on bottom filling of a flexible board. By selecting a suitable interface interconnect material for double-sided heat dissipation of GaN devices, an interface interconnect process based on bottom filling of a flexible board is realized. The double-sided heat dissipation structure of GaN devices is realized in a hermetically sealed housing, giving the GaN devices with double-sided heat dissipation structure the characteristics of high integration.
[0006] In one aspect, a double-sided heat dissipation structure for GaN devices based on bottom filling of a flexible board is provided, including a cover plate, a frame, a ceramic substrate, a GaN device, a thermal interface material, solder joints, and a flexible insulating copper-clad laminate.
[0007] The GaN device is electrically interconnected with the ceramic substrate via solder joints. The electrical interconnection between the GaN device and the ceramic substrate is achieved using a nanomaterial sintering process. A flexible insulating copper-clad laminate is sintered between the bottom electrodes of the GaN device, and the flexible insulating copper-clad laminate is located between the GaN device and the ceramic substrate. A frame surrounds the GaN device and is disposed on the ceramic substrate. A cover plate is disposed above the frame, and a thermal interface material is disposed between the GaN device and the cover plate. The thermal interface material is coated on the GaN device, and the cover plate is in contact with the thermal interface material to achieve heat dissipation from the GaN device to the cover plate.
[0008] In conjunction with the first aspect, in some implementations of the first aspect, the packaging structure used for GaN devices is a ball grid array structure or a grid array structure.
[0009] In conjunction with the first aspect, in some implementations of the first aspect, the ceramic substrate is selected from AlN or Al2O3.
[0010] In conjunction with the first aspect, in some implementations of the first aspect, the electrical interconnection between the GaN device and the ceramic substrate is achieved using a nano-silver sintering process or a nano-copper sintering process.
[0011] In conjunction with the first aspect, in some implementations of the first aspect, the thermal interface material is an epoxy adhesive with thermally conductive and insulating properties, a thermal conductivity higher than 3.5 W / m·℃, and a dielectric strength higher than 29000 V / mm; at the same time, the thermal interface material meets the test index requirements for internal gas content and particle collision noise detection after the product is sealed.
[0012] In conjunction with the first aspect, in some implementations of the first aspect, a parallel seam welding process is used to seal the cover plate.
[0013] In conjunction with the first aspect, in some implementations of the first aspect, the frame and cover plate are made of Kovar alloy.
[0014] In conjunction with the first aspect, in some implementations of the first aspect, the ceramic substrate, frame, and cover undergo a hydrogen removal process after production, requiring that the hydrogen content inside the sealed product does not exceed 1000 ppm.
[0015] Secondly, a packaging method for a double-sided heat dissipation structure as described in any of the implementations of the first aspect above is provided, comprising:
[0016] Flexible insulating copper-clad laminates are sintered onto adjacent electrodes of GaN devices using nanomaterials.
[0017] The GaN device is electrically interconnected with the ceramic substrate through solder joints to complete the GaN device flip-chip bonding.
[0018] A frame is set on a ceramic substrate to encapsulate the GaN device within the frame;
[0019] Step 4: Uniformly coat the back of the GaN device with thermal interface material, ensuring that the thermal interface material does not flow to the solder joints sintered on the front of the GaN device.
[0020] After the thermal interface material is coated, the cover plate is assembled onto the frame. By controlling the internal height of the product, the cover plate is made to contact the thermal interface material. After the cover plate is assembled, it is baked at 150°C. After baking, it is sealed using a parallel seam welding process, thereby realizing the double-sided heat dissipation packaging structure of GaN devices.
[0021] In conjunction with the second aspect, in certain implementations of the second aspect, the method satisfies at least one of the following:
[0022] The frame and the ceramic substrate are brazed using a silver-copper welding process.
[0023] Nanomaterials are printed on a ceramic substrate. A GaN device with a pre-placed flexible insulating copper-clad laminate is pre-attached to the ceramic substrate using a thermal bonding machine. The interconnection between the GaN device and the ceramic substrate is achieved using a pressureless sintering process.
[0024] Compared with the prior art, the solution provided by the present invention has at least the following beneficial technical effects:
[0025] (1) High integration packaging of GaN devices was achieved by flip-chip bonding of GaN devices;
[0026] (2) Through the sintering process of nano-metal materials, GaN devices with high thermal conductivity interconnection and excellent high-temperature service performance were achieved;
[0027] (3) By sintering a flexible insulating copper-clad laminate between the bottom metal electrodes in a flip-chip soldering process, the problem of electromigration between sintered solder joints is avoided, and the thermal conductivity of the device is further improved.
[0028] (4) GaN devices achieve double-sided heat dissipation by contacting the cover plate through a thermal interface material.
[0029] (5) The device achieves a double-sided heat dissipation structure for GaN devices while also achieving hermetically sealed packaging. Attached Figure Description
[0030] Figure 1 This is a schematic diagram of the flip-chip package structure for GaN devices.
[0031] Figure 2 This is a schematic diagram of a double-sided heat dissipation structure based on GaN devices.
[0032] Reference numerals: 1. Cover plate, 2. Frame, 3. Ceramic substrate, 4. GaN device, 5. Thermal interface material, 6. Solder joint, 7. Flexible insulating copper clad laminate. Detailed Implementation
[0033] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0034] This invention provides a double-sided heat dissipation structure for GaN devices based on bottom filling of a flexible board. This double-sided heat dissipation structure employs a GaN device with a flip-chip structure, the device structure of which is as follows... Figure 1 As shown, the double-sided heat dissipation structure based on this GaN device is as follows: Figure 2 As shown. The double-sided heat dissipation structure includes a cover plate 1, a frame 2, a ceramic substrate 3, a GaN device 4, a thermal interface material 5, solder joints 6, and a flexible insulating copper-clad laminate 7.
[0035] The GaN device 4 is electrically interconnected with the ceramic substrate 3 via solder joints 6. This electrical interconnection between the GaN device 4 and the ceramic substrate 3 is achieved using a nanomaterial sintering process. A flexible insulating copper-clad laminate 7 is sintered between the bottom electrodes of the GaN device 4, and the flexible insulating copper-clad laminate 7 is located between the GaN device 4 and the ceramic substrate 3. A frame 2 surrounds the GaN device 4 and is disposed on the ceramic substrate 3. A cover plate 1 is disposed above the frame 2, meaning the frame 2 is located between the cover plate 1 and the ceramic substrate 3. A thermal interface material 5 is disposed between the GaN device 4 and the cover plate 1, and the thermal interface material 5 is coated on the GaN device 4 to achieve heat dissipation from the GaN device 4 to the cover plate 1.
[0036] Before sintering the solder joints 6, a flexible insulating copper-clad laminate 7 is first sintered between the bottom electrodes of the GaN device 4. Then, nanomaterials are printed on the ceramic substrate 3. After the GaN device 4 is mounted, pressureless sintering is performed. By pre-sintering the flexible insulating copper-clad laminate 7 between the bottom electrodes of the device, the insulation between adjacent electrodes can be improved, preventing electromigration and electrochemical migration problems between the sintered silver solder joints 6. At the same time, the flexible structure filling facilitates the reduction of mechanical stress and also helps to reduce the overall thermal stress of the device.
[0037] In some embodiments, the GaN device 4 uses a ball grid array (BGA) or grid array (LGA) packaging structure.
[0038] In some embodiments, the GaN device 4 is housed in an SMD ceramic package, and the sealing is achieved using a parallel seam welding process.
[0039] In some embodiments, the ceramic substrate 3 is made of a material with high thermal conductivity. For example, the ceramic substrate 3 can be made of ceramic materials such as AlN and Al2O3, and the selection can be made according to the device's heat dissipation requirements and cost.
[0040] In some embodiments, the electrical interconnection between the GaN device 4 and the ceramic substrate 3 is achieved using nanomaterial sintering processes such as nano-silver sintering and nano-copper sintering. This ensures excellent electrical and thermal conductivity while maintaining a high service temperature, preventing the internal solder joints 6 of the GaN device 4 from melting during board-level interconnection.
[0041] The types of thermal interface material 5 include thermally conductive adhesives, thermally conductive gels, etc. In some embodiments, the thermal interface material 5 can be an epoxy adhesive with thermally conductive and insulating properties, a thermal conductivity higher than 3.5 W / m·℃, and a dielectric strength higher than 29000 V / mm; at the same time, the thermal interface material 5 must meet the requirements of the product after sealing for internal gas content (5000 ppm water vapor content) and particle collision noise detection (PIND, 20g, 40Hz).
[0042] In some embodiments, the cover plate 1 is sealed using a parallel seam welding process, so that the cover plate 1 comes into contact with the thermal interface material 5 after sealing, thereby achieving double-sided heat dissipation.
[0043] In some embodiments, the frame 2 and the cover plate 1 are made of Kovar alloy.
[0044] In some embodiments, the ceramic substrate 3, the frame 2, and the cover plate 1 need to undergo a hydrogen removal process after production, requiring that the hydrogen content inside the product after sealing and packaging does not exceed 1000ppm.
[0045] The present invention also provides a packaging method for a GaN device with a double-sided heat dissipation structure based on bottom filling of a flexible board.
[0046] Step 1: A flexible insulating copper-clad laminate 7 is sintered onto the adjacent electrodes of the GaN device 4 using nanomaterials.
[0047] Step 2: Electrically interconnect the GaN device 4 with the ceramic substrate 3 via solder joint 6 to complete the flip-chip bonding of the GaN device 4.
[0048] In some embodiments, nanomaterials are printed on a ceramic substrate 3, and a GaN device 4 with a pre-placed flexible insulating copper-clad laminate 7 is pre-attached to the ceramic substrate 3 using a thermal bonding machine. A low-stress interconnect between the GaN device 4 and the ceramic substrate 3 is achieved using a pressureless sintering process.
[0049] In some embodiments, in step 2, the flip-chip interconnect process of GaN device 4 is sintering of nanomaterials, including nanosilver, nanocopper, etc.
[0050] Step 3: Set a frame 2 on the ceramic substrate 3 so that the GaN device 4 is encapsulated in the frame 2.
[0051] In some embodiments, the frame 2 and the ceramic substrate 3 are brazed using a silver-copper welding process.
[0052] Step 4: Apply thermal interface material 5 uniformly to the back side of GaN device 4. The thermal interface material 5 must not flow to the solder joints 6 sintered on the front side of GaN device 4.
[0053] Step 5: After coating with thermal interface material 5, the cover plate 1 is assembled onto the frame 2. By controlling the internal height of the product, the cover plate 1 is brought into contact with the thermal interface material 5. After assembly, the cover plate 1 is baked at 150°C. After baking, a parallel seam welding process is used to seal the cover, thereby realizing the double-sided heat dissipation packaging structure of the GaN device 4.
[0054] In summary, this invention proposes a silver sintering process based on a flexible plate filling the bottom of the metal electrodes for flip-chip GaN devices. In addition to front-side soldering for heat dissipation, a back-side heat dissipation path is developed to achieve double-sided heat dissipation for GaN devices.
[0055] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims of the present invention.
Claims
1. A double-sided heat dissipation structure for GaN devices based on bottom filling of a flexible board, characterized in that, Includes cover plate (1), frame (2), ceramic substrate (3), GaN device (4), thermal interface material (5), solder joint (6), flexible insulating copper clad laminate (7); The GaN device (4) is electrically interconnected with the ceramic substrate (3) through solder joints (6). The electrical interconnection between the GaN device (4) and the ceramic substrate (3) is achieved by a nano-metal sintering process. A flexible insulating copper-clad laminate (7) is sintered between the bottom electrodes of the GaN device (4). The flexible insulating copper-clad laminate (7) is located between the GaN device (4) and the ceramic substrate (3). A frame (2) surrounds the GaN device (4) and is disposed on the ceramic substrate (3). A cover plate (1) is disposed above the frame (2). A thermal interface material (5) is disposed between the GaN device (4) and the cover plate (1). The thermal interface material (5) is coated on the GaN device (4). The cover plate (1) contacts the thermal interface material (5) to achieve heat dissipation from the GaN device (4) to the cover plate (1).
2. The double-sided heat dissipation structure according to claim 1, characterized in that, The packaging structure used in GaN devices (4) is a ball grid array structure or a grid array structure.
3. The double-sided heat dissipation structure according to claim 1, characterized in that, The ceramic substrate (3) is selected from AlN or Al2O3.
4. The double-sided heat dissipation structure according to claim 1, characterized in that, The electrical interconnection between the GaN device (4) and the ceramic substrate (3) is achieved by nano-silver sintering or nano-copper sintering.
5. The double-sided heat dissipation structure according to claim 1, characterized in that, The thermal interface material (5) is an epoxy adhesive with thermal conductivity and insulation properties. Its thermal conductivity is higher than 3.5W / m·℃ and its dielectric strength is higher than 29000V / mm. At the same time, the thermal interface material (5) meets the test index requirements for internal gas content and particle collision noise detection after the product is sealed.
6. The double-sided heat dissipation structure according to claim 1, characterized in that, The cover plate (1) is sealed using a parallel seam welding process.
7. The double-sided heat dissipation structure according to claim 1, characterized in that, The frame (2) and cover plate (1) are made of Kovar alloy.
8. The double-sided heat dissipation structure according to claim 1, characterized in that, After production, the ceramic substrate (3), the frame (2) and the cover plate (1) undergo a hydrogen removal process, requiring that the hydrogen content inside the product after sealing and packaging does not exceed 1000ppm.
9. A packaging method for a double-sided heat dissipation structure as described in any one of claims 1 to 8, characterized in that, include: A flexible insulating copper-clad laminate (7) is sintered between adjacent electrodes of the GaN device (4) using nanomaterials; The GaN device (4) is electrically interconnected with the ceramic substrate (3) through solder joints (6) to complete the flip-chip bonding of the GaN device (4); A frame (2) is provided on the ceramic substrate (3) so that the GaN device (4) is encapsulated within the frame (2); A thermal interface material (5) is uniformly coated on the back side of the GaN device (4), and the thermal interface material (5) cannot flow to the solder joint (6) sintered on the front side of the GaN device (4). After the thermal interface material (5) is coated, the cover plate (1) is assembled onto the frame (2). By controlling the internal height of the product, the cover plate (1) is made to contact the thermal interface material (5). After the cover plate (1) is assembled, a baking process at 150°C is carried out. After baking, a parallel seam welding process is used to seal the cover, thereby realizing the double-sided heat dissipation packaging structure of the GaN device (4).
10. The method according to claim 9, characterized in that, The method satisfies at least one of the following: The frame (2) and the ceramic substrate (3) are brazed using a silver-copper welding process; Nanomaterials are printed on a ceramic substrate (3). A GaN device (4) with a pre-placed flexible insulating copper-clad laminate (7) is pre-attached to the ceramic substrate (3) using a hot-mount machine. The interconnection between the GaN device (4) and the ceramic substrate (3) is achieved using a pressureless sintering process.