High-reliability high-power-density ceramic surface-mounted airtight packaging structure

Abstract

The utility model discloses a high-reliability high-power-density ceramic surface-mounted airtight packaging structure, which comprises a ceramic shell, and a chip sintering area is arranged at the top of the ceramic shell. A large electrode plate and a small electrode plate are respectively arranged on the side wall of the ceramic shell, the large electrode plate is used for being electrically connected with a source electrode of the chip, the small electrode plate is used for being electrically connected with a grid electrode of the chip, and a heat dissipation piece is arranged at the top of the ceramic shell; and the working temperature of the chip is reduced, so that the good working performance of the chip is guaranteed, and the normal operation of the whole system is facilitated.

Description

Technical Field

[0001] The utility model relates to the field of airtight packaging shells, in particular to a high-reliability and high-power-density ceramic surface-mount airtight packaging structure. Background Art

[0002] The airtight surface mount package shell currently available on the market is composed of a tungsten copper base, a ceramic shell, copper leads and a Kovar cover plate that are fired at high temperature. It is usually used for packaging power devices such as IGBT, MOS, and BJT. Taking MOS as an example, when using this shell to package a device, refer to Figure 3 First, the drain of the MOS chip 11 is sintered on the tungsten copper base 15 through solder 12, and then the gate and source of the chip are led to the electrode lead-out terminal 14 with aluminum wire 13 through ultrasonic bonding process, and finally the tube shell is sealed through parallel seam welding process.

[0003] When the packaged device is used in a circuit, it is often installed on a PCB circuit board through reflow soldering, which greatly alleviates the stress caused by the deformation of the PCB circuit board and effectively ensures that the device will not produce cracks, air leaks and other problems, thereby improving the reliability of the device.

[0004] However, this structure also has some problems. The bottom of the device serves as both an electrode and a heat sink. For power devices, this structure causes the heat emitted by the chip to be introduced into the PCB circuit board through the tungsten copper base 15 and then dissipated outward. However, due to the high thermal resistance and poor thermal conductivity of the PCB circuit board, the heat dissipation effect is poor. At the same time, the heat emitted by the chip also causes the overall temperature of the PCB circuit board to be very high. As a result, the operating temperature of the components around the power device that have low heat generation is raised due to the increase in the temperature of the PCB circuit board, and their performance deteriorates at high temperatures, which in turn has an adverse impact on the operation of the entire system. Utility Model Content

[0005] In order to solve the above technical problems, the utility model provides a high-reliability and high-power density ceramic surface-mount airtight packaging structure.

[0006] The utility model is achieved through the following technical solutions.

[0007] The utility model provides a high-reliability and high-power density ceramic surface-mount airtight packaging structure, comprising a ceramic shell, wherein a chip sintering area is provided on the top of the ceramic shell;

[0008] The side walls of the ceramic shell are respectively provided with a large electrode sheet and a small electrode sheet. The large electrode sheet is used to be electrically connected to the source of the chip, and the small electrode sheet is used to be electrically connected to the gate of the chip. A heat sink is provided on the top of the ceramic shell.

[0009] Preferably, the heat sink is configured as a connecting plate, which is "L"-shaped, with the horizontal portion of the connecting plate being fitted on the top of the inner side of the ceramic shell, and the vertical portion of the connecting plate being fitted on the inner wall of the ceramic shell, extending to the bottom of the ceramic shell.

[0010] Preferably, a top heat sink is provided on the top of the outer side of the ceramic shell.

[0011] Preferably, the bottom of the ceramic shell is opened.

[0012] Preferably, a Kovar metal frame is provided at the open end of the ceramic shell, and a cover plate is attached to the Kovar metal frame.

[0013] Preferably, the connecting piece is made of tungsten copper.

[0014] Preferably, the top heat sink is made of tungsten copper.

[0015] Preferably, the cover plate is provided with a "convex" platform shape.

[0016] The beneficial effects of the present invention are:

[0017] 1. By encapsulating the chip on a ceramic shell, the drain of the chip is flipped upside down and close to the top surface of the ceramic shell, so that the connecting piece and the top heat sink on the top of the ceramic shell dissipate the heat generated by the chip from the top of the ceramic shell. At the same time, the conductivity of the chip is enhanced when it is electrically connected to the large electrode sheet and the small electrode sheet, which reduces the package resistance and the operating temperature of the chip, thereby ensuring the good working performance of the chip and facilitating the normal operation of the entire system.

[0018] 2. Under the same package size, the rated design power of the chip can be fully utilized, which greatly improves the application power density of the device and effectively reduces the system volume. Moreover, because the heat dissipation path does not pass through the PCB, it will not cause the temperature of the PCB to rise, nor will it affect other devices placed on the PCB. Users can install and use it by soldering with the PCB patch in the same way as existing packages. The installation is convenient and the chip can be protected at the same time, making it less likely to be damaged, thereby extending the chip's service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic cross-sectional structural diagram of the present utility model;

[0020] Figure 2 This is a partial structural diagram of the utility model mainly used to show the chip sintering area, large electrode sheet, small electrode sheet and ceramic shell structure;

[0021] Figure 3This utility model is mainly used to illustrate the overall structure of the MOS chip package in the background technology;

[0022] Explanation of the reference numerals: 1-chip sintering area; 2-large electrode sheet; 3-small electrode sheet; 4-top heat sink; 5-ceramic shell; 6-connecting sheet; 7-Kovar metal frame; 8-cover plate; 9-first perforation; 10-second perforation; 11-MOS chip; 12-solder; 13-aluminum wire; 14-electrode lead end; 15-tungsten copper base. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0025] In the examples of this application, refer to Figure 1 and Figure 2 The chip sintering area 1 is provided on the top of the ceramic shell 5.

[0026] In the examples of this application, refer to Figure 1 A top heat sink 4 is provided on the top of the outer side of the ceramic shell 5. The top heat sink 4 is made of tungsten-copper material and has high thermal conductivity. At the same time, the expansion coefficient of the top heat sink 4 is close to that of the ceramic shell 5, which avoids deformation during the heat conduction process as much as possible. It is installed on the ceramic shell 5 by silver-copper welding, which helps to dissipate heat from the chip.

[0027] In the examples of this application, refer to Figure 1 and Figure 2The side walls on the same side of the ceramic shell 5 are respectively provided with a first through-hole 10 and a second through-hole 11. The first through-hole 10 is penetrated by a large electrode sheet 2, and the second through-hole 11 is penetrated by a small electrode sheet 3. Both the large electrode sheet 2 and the small electrode sheet 3 are made of pure copper material. The large electrode sheet 2 is electrically connected to the source of the chip through an aluminum wire, and the small electrode sheet 3 is electrically connected to the gate of the chip through an aluminum wire. It can enhance the conductivity of the packaged chip to a certain extent, and at the same time reduce the package resistance, thereby ensuring that the good working performance of the chip is not affected by the packaging process.

[0028] In an embodiment of the present application, a heat sink is provided on the top of the ceramic shell 5, and the heat sink is configured as a connecting piece 6. The connecting piece 6 is "L"-shaped and is made of tungsten copper material with high thermal conductivity. The connecting piece 6 can also use materials with high thermal conductivity such as CPC and CMC, so that the expansion coefficient of the connecting piece 6 is close to that of the ceramic shell 5, thereby avoiding deformation of the connecting piece 6 during the conductive heat dissipation process as much as possible; the horizontal part of the connecting piece 6 is fitted on the top of the inner side of the ceramic shell 5; the vertical part of the connecting piece 6 is fitted on the inner wall of the ceramic shell 5, and the vertical part of the connecting piece 6 extends to the bottom of the ceramic shell 5, so that the connecting piece 6 can guide the drain current of the chip to the bottom of the ceramic shell 5.

[0029] In the embodiment of the present application, a Kovar metal frame 7 is provided at the open end of the ceramic shell 5, and a cover plate 8 is fitted on the Kovar metal frame 7. The cover plate 8 is provided with a "convex" platform shape, and the protruding side of the cover plate 8 is facing away from the open end of the ceramic shell 5, which is conducive to the installation of the cover plate 8 on the ceramic shell 5. When the device is used later, the effect of mechanical stress on the opening of the ceramic shell 5 is effectively reduced, and stress fatigue damage and the like of the device during use are avoided as much as possible.

[0030] In the embodiment of the present application, the cover plate 8 is also in contact with the vertical portion of the connecting piece 6, which facilitates the welding and installation of the PCB patch and the packaged device. The heat dissipation path of the chip does not pass through the PCB patch, thereby preventing the increase in chip temperature from affecting the increase in PCB patch temperature, thereby avoiding affecting other devices on the PCB.

[0031] The working principle of this embodiment is as follows: by encapsulating the chip on the ceramic shell 5, the drain of the chip is flipped upside down and tightly attached to the top of the inner side of the ceramic shell, so that the connecting piece 6 and the top heat sink 4 on the top of the ceramic shell 5 dissipate the heat generated by the chip from the top of the ceramic shell 5. At the same time, the conductivity of the chip is enhanced when it is electrically connected to the large electrode sheet 2 and the small electrode sheet 3, thereby reducing the package resistance and the operating temperature of the chip. At the same time, the chip heat dissipation path does not pass through the bottom of the ceramic shell 5, so that when the packaged ceramic shell 5 is connected and installed with the PCB, the temperature generated by the chip will not affect the PCB patch and other devices around the PCB patch. While ensuring the good working performance of the chip, it can also avoid affecting the normal operation of the PCB patch, which is beneficial to the normal operation of the entire system.

[0032] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. All equivalent structural transformations made based on the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A high-reliability, high-power-density ceramic surface-mount airtight packaging structure, characterized by: The invention comprises a ceramic shell (5), wherein a chip sintering area (1) is provided on the top of the ceramic shell (5); a large electrode sheet (2) and a small electrode sheet (3) are respectively provided on the side walls of the ceramic shell (5), wherein the large electrode sheet (2) is used for electrically connecting to the source electrode of the chip, and the small electrode sheet (3) is used for electrically connecting to the gate electrode of the chip; and a heat sink is provided on the top of the ceramic shell (5).

2. The high-reliability, high-power-density ceramic surface-mount airtight packaging structure according to claim 1, characterized in that: The heat sink is configured as a connecting piece (6), the connecting piece (6) is L-shaped, the horizontal portion of the connecting piece (6) is fitted on the top of the inner side of the ceramic shell (5), the vertical portion of the connecting piece (6) is fitted on the inner side wall of the ceramic shell (5), and the vertical portion of the connecting piece (6) extends to the bottom of the ceramic shell (5).

3. The high-reliability, high-power-density ceramic surface-mount airtight packaging structure according to claim 1, characterized in that: A top heat sink (4) is provided on the top of the outer side of the ceramic shell (5).

4. The high-reliability, high-power-density ceramic surface-mount airtight packaging structure according to claim 1, wherein: The bottom of the ceramic shell (5) is open.

5. The high-reliability, high-power-density ceramic surface-mount airtight packaging structure according to claim 1, wherein: A Kovar metal frame (7) is provided at the open end of the ceramic shell (5), and a cover plate (8) is attached to the Kovar metal frame (7).

6. The high-reliability, high-power-density ceramic surface-mount airtight packaging structure according to claim 2, wherein: The connecting piece (6) is made of tungsten copper.

7. The high-reliability, high-power-density ceramic surface-mount airtight packaging structure according to claim 3, characterized in that: The top heat sink (4) is made of tungsten copper.

8. The high-reliability, high-power-density ceramic surface-mount airtight packaging structure according to claim 5, characterized in that: The cover plate (8) is configured to be in a "convex" platform shape.

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