Double-sided heat dissipation low-resistance CSMD ceramic tube shell

Abstract

According to the technical scheme, the double-face heat dissipation low-resistance CSMD ceramic tube shell comprises a substrate, the upper surface of the substrate is metalized, a sealing ring is welded to the upper surface of the substrate, an MOS tube located in the sealing ring is arranged on the upper surface of the substrate, the D electrode of the MOS tube is welded to the metalized surface of the substrate, and the D electrode of the MOS tube is welded to the metalized surface of the substrate. A flat sealing cover plate is welded on the upper surface of the sealing ring, a ceramic plate positioned above the MOS tube in the sealing ring is welded on the lower surface of the flat sealing cover plate, and a G-pole electrode and an S-pole electrode on the MOS tube are conducted to the upper surface of the flat sealing cover plate. According to the invention, the D electrode of the chip is attached to the substrate, the bottom surface of the substrate is metalized, the substrate is conducted with the sealing ring, the conduction resistance is reduced while the conduction is ensured, and the current flows through the sealing ring and then is output through the flat sealing cover plate which is flatly sealed with the sealing ring, namely, the flat sealing cover plate becomes a leading-out end of the ceramic tube shell; most of the current is conducted through the metal piece, and the conduction resistance can reach a very ideal value.

Description

Technical Field

[0001] The invention relates to the technical field of MOS tubes, in particular to a CSMD ceramic tube shell with double-sided heat dissipation and low resistance. Background Art

[0002] MOS tube is a common electronic component, mainly used as a switch or amplifier in electronic circuits. MOS tube has high input impedance and simple manufacturing process, which makes it very useful in highly integrated circuit design.

[0003] The existing packaging forms for MOS tubes include plug-in type and surface mount type. Common plug-in packages include dual in-line package (DIP), transistor outline package (TO), and pin grid array package (PGA). In the surface mount type, the pins and heat dissipation flange of the MOSFET are welded to the pads on the surface of the PCB board. Typical surface mount packages include: transistor outline (D-PAK), small outline transistor (SOT), small outline package (SOP), square flat package (QFP), plastic package lead chip carrier (PLCC), etc. For the ceramic packaging form of the surface-mount MOS tube, whether it is DIP, CSOP or CSMD series ceramic shells, the circuit of the MOS tube chip is connected to the outside of the shell through the internal wiring of the ceramic shell. The slurry used for wiring is metal tungsten, and the circuit is formed by printing tungsten slurry for lamination and hole filling.

[0004] However, when the circuit is turned on by tungsten slurry, its resistance value will be relatively high. The resistance value is limited by many factors such as the conduction band width, the diameter and number of through holes, the thickness of the tungsten slurry, the resistivity of the tungsten slurry itself, etc., which makes it difficult to reduce the on-resistance after a certain level. At the same time, the ceramic shell has limited heat dissipation capacity for the chip. The thermal conductivity of ceramics is a fixed coefficient. For chips with too high power, it cannot provide a good heat dissipation environment. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a CSMD ceramic tube shell with double-sided heat dissipation and low resistance.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows:

[0007] A double-sided heat dissipation and low-resistance CSMD ceramic tube shell comprises a substrate, the upper surface of the substrate is metallized, a sealing ring is welded to the upper surface of the substrate, a MOS tube located in the sealing ring is arranged on the upper surface of the substrate, and the D pole of the MOS tube is welded to the metallized surface of the substrate, a flat sealing cover plate is welded to the upper surface of the sealing ring, and a ceramic plate located above the MOS tube in the sealing ring is welded to the lower surface of the flat sealing cover plate, and the G pole electrode and the S pole electrode on the MOS tube are both connected to the upper surface of the flat sealing cover plate.

[0008] Preferably, the ceramic plate is provided with two cavities, and the S-pole electrode and the G-pole electrode respectively penetrate the two cavities of the ceramic plate and are sealed with the surface of the ceramic plate.

[0009] Preferably, the G-pole electrode and the S-pole electrode are both configured to be electrodes made of tungsten-copper material, specifically W85Cu15.

[0010] Preferably, the G-pole electrode and the S-pole electrode are both configured as T-shaped structures.

[0011] Preferably, the cross-sectional area of ​​the substrate is larger than the cross-sectional area of ​​the MOS tube, and the area difference is no more than one twentieth of the cross-sectional area of ​​the MOS tube.

[0012] Preferably, a heat sink is welded to the bottom of the substrate.

[0013] Preferably, the substrate is configured as a plate body made of AlN material, and the ceramic plate is configured as a plate body made of Al2O3 material.

[0014] Preferably, the sealing ring and the flat sealing cover plate are both configured as frames made of Kovar material, the sealing ring is specifically configured as 4J29 material, and the flat sealing cover plate is specifically configured as 4J42 material.

[0015] A process flow for the above-mentioned double-sided heat dissipation low-resistance CSMD ceramic tube shell is also provided, which specifically includes the following steps:

[0016] S1, the sealing ring is welded on the upper surface of the substrate by means of sealing ring solder to form a bottom plate assembly, and the flat sealing cover plate is welded on the upper surface of the ceramic plate by means of cover plate solder to form a cover plate assembly;

[0017] S2, the MOS tube is soldered on the upper surface of the substrate through the MOS tube solder to form a chip mounting assembly;

[0018] S3, the S-pole electrode and the G-pole electrode are respectively welded to the upper surface of the MOS tube by using the S-pole preset solder and the G-pole preset solder;

[0019] S4, the flat sealing cover plate is welded parallel to the upper surface of the sealing ring to form a chip packaging assembly;

[0020] S5. The S-pole electrode and the G-pole electrode are respectively welded to the surface of the ceramic plate by using the S-pole electrode solder and the G-pole electrode solder to complete the welding work.

[0021] Preferably, the sealing ring solder and the cover plate solder are both set to silver-copper solder, specifically Ag72Cu28, the MOS tube solder is set to gold-germanium solder, specifically Au88Ge12, and the S-pole electrode solder, S-pole preset solder, G-pole electrode solder and G-pole preset solder are all set to gold-tin solder, specifically Au80Sn20.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention fits the chip D pole to the substrate, metalizes the bottom surface of the substrate, and conducts with the sealing ring. While ensuring conduction, the sealing ring made of Kovar material further reduces the conduction resistance. At the same time, the bottom aluminum nitride substrate has excellent heat dissipation capacity, providing a good heat dissipation environment for the tube shell. The current flows through the sealing ring and then outputs through the flat sealing cover plate that is flatly sealed with the sealing ring. That is, the flat sealing cover plate becomes the lead-out end of the ceramic tube shell. In this way, most of the current is conducted through the metal parts, and its conduction resistance will reach a very ideal value;

[0024] 2. The present invention conducts to the outside of the tube shell through electrodes made of tungsten copper. This form of direct conduction through metal greatly reduces the on-resistance. Compared with conventional ceramic packaging tube shells, the gold wire bonding process is omitted. The large-area conduction electrode is good for current and heat dissipation.

[0025] 3. During welding, the present invention first performs silver-copper welding, then gold-germanium welding, and finally gold-tin welding, thereby realizing a three-level temperature gradient from high to low, ensuring that the first two solders will not melt again during subsequent welding, thereby ensuring the stability of the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The disclosure of the present invention is described with reference to the accompanying drawings. It should be understood that the drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In the drawings, the same reference numerals are used to refer to the same components. Among them:

[0027] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0028] Figure 2 It is a schematic diagram of the explosion structure of the present invention;

[0029] Figure 3 It is a process flow chart of the present invention.

[0030] Explanations in the figure: 1. Substrate; 2. Sealing ring; 3. MOS tube; 4. Ceramic plate; 5. Flat sealing cover plate; 6. S-pole electrode; 7. G-pole electrode; 8. S-pole electrode solder; 9. S-pole pre-set solder; 10. G-pole electrode solder; 11. G-pole pre-set solder; 12. Cover plate solder; 13. MOS tube solder; 14. Sealing ring solder. DETAILED DESCRIPTION

[0031] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific implementation modes and drawings are only exemplary descriptions of the technical solution of the present invention, and should not be regarded as the whole of the present invention or as a limitation or restriction to the technical solution of the present invention.

[0032] like Figure 1 , 2 As shown, as a double-sided heat dissipation and low-resistance CSMD ceramic tube shell of the present invention, it includes a substrate 1, and the substrate 1 is set as a plate body made of AlN material. Aluminum nitride itself has a high thermal conductivity of >170W / m·K, providing a large heat dissipation area, and metallization covers both the front and back surfaces to provide support for the conduction of the chip. A sealing ring 2 is welded to the upper surface of the substrate 1 through a sealing ring solder 14, and a MOS tube 3 located in the sealing ring 2 is arranged on the upper surface of the substrate 1, and the D pole of the MOS tube 3 is welded to the metallized surface of the substrate 1 through a MOS tube solder 13. The MOS tube solder 13 is set as gold germanium solder, specifically Au88Ge12, and a dam structure is formed by welding the substrate 1 and the sealing ring 2 to provide support for chip packaging;

[0033] A flat sealing cover plate 5 is welded on the upper surface of the sealing ring 2. The sealing ring 2 and the flat sealing cover plate 5 are both configured as a frame made of Kovar material. The sealing ring 2 is specifically configured as 4J29 material. 4J29 has a thermal expansion coefficient similar to that of ceramics and has excellent electrical conductivity and low cost. The flat sealing cover plate 5 is specifically configured as 4J42 material. A ceramic plate 4 is welded to the lower surface of the flat sealing cover plate 5 through a cover plate solder 12. The sealing ring solder 14 and the cover plate solder 12 are both configured as silver-copper solder, specifically Ag72Cu28. The ceramic plate 4 is configured as a plate body made of Al2O3 material. Alumina ceramic is selected as the secondary heat dissipation surface. The ceramic plate 4 is located at the sealing ring 2, S-pole electrode 6 and G-pole electrode 7 are welded on both sides of the upper surface of MOS tube 3 through S-pole pre-set solder 9 and G-pole pre-set solder 11, respectively. Ceramic plate 4 is provided with two cavities. S-pole electrode 6 and G-pole electrode 7 respectively penetrate the two cavities of ceramic plate 4 and are respectively welded on the surface of ceramic plate 4 through S-pole electrode solder 8 and G-pole electrode solder 10. S-pole electrode solder 8, S-pole pre-set solder 9, G-pole electrode solder 10 and G-pole pre-set solder 11 are all set to gold-tin solder, specifically Au80Sn20, to ensure the airtightness of tube shell and make S-pole electrode 6 and G-pole electrode 7 conduct to the upper surface of flat cover plate 5;

[0034] The D pole of the MOS tube 3 is fitted to the substrate 1, and the metalized surface of the substrate 1 is connected to the sealing ring 2. While ensuring the conduction, the sealing ring 2 made of Kovar material further reduces the on-resistance. At the same time, the bottom aluminum nitride substrate 1 has excellent heat dissipation capacity, providing a good heat dissipation environment for the tube shell. The current flows through the sealing ring 2 and then outputs through the flat sealing cover plate 5 that is flatly sealed with the sealing ring 2, that is, the flat sealing cover plate 5 becomes the lead-out end of the ceramic tube shell. In this way, most of the current is conducted through the metal parts, and its on-resistance will reach a very ideal value.

[0035] The G-pole electrode 7 and the S-pole electrode 6 are both configured as electrodes made of tungsten copper, specifically W85Cu15, which has better conductivity and heat dissipation performance and can be welded with the MOS tube 3 and the ceramic plate 4 to ensure conduction and airtightness. At the same time, the electrodes made of tungsten copper are conducted to the outside of the tube shell. This form of direct conduction through metal greatly reduces the conduction resistance. Compared with conventional ceramic packaging tube shells, the gold wire bonding process is omitted. The large-area conduction electrode is good for current and heat dissipation. The G-pole electrode 7 and the S-pole electrode 6 are both configured as T-shaped structures to ensure the airtightness of gold soldering.

[0036] The cross-sectional area of ​​the substrate 1 is larger than the cross-sectional area of ​​the MOS tube 3, and the area difference is not greater than one twentieth of the cross-sectional area of ​​the MOS tube 3, which solves the problem that the existing ceramic packaging shell for the surface-mount MOS tube 3 is limited by factors such as the wiring inside the ceramic, and the volume is relatively large, and there is a lot of wasted space inside the shell required for packaging a single chip. A heat sink is welded on the bottom of the substrate 1 to increase heat dissipation and improve heat dissipation performance.

[0037] like Figure 3 As shown, the present invention also provides a process flow applied to the above-mentioned double-sided heat dissipation low-resistance CSMD ceramic tube shell, which specifically includes the following steps:

[0038] S1, the sealing ring 2 is welded to the upper surface of the substrate 1 by the sealing ring solder 14 to form a bottom plate assembly, and the flat sealing cover plate 5 is welded to the upper surface of the ceramic plate 4 by the cover plate solder 12 to form a cover plate assembly;

[0039] S2, MOS tube 3 are soldered to the upper surface of substrate 1 by MOS tube solder 13 to form a chip mounting assembly;

[0040] S3, S-pole electrode 6 and G-pole electrode 7 are respectively welded to the upper surface of MOS tube 3 through S-pole pre-welded solder 9 and G-pole pre-welded solder 11;

[0041] S4, the flat sealing cover plate 5 is welded parallel to the upper surface of the sealing ring 2 to form a chip packaging assembly;

[0042] S5, the S-pole electrode 6 and the G-pole electrode 7 are respectively welded to the surface of the ceramic plate 4 through the S-pole electrode solder 8 and the G-pole electrode solder 10 to complete the welding work.

[0043] During welding, silver-copper soldering is performed first, and the silver-copper brazing temperature is set to 820°C. Next, gold-germanium soldering is performed, and the gold-germanium soldering temperature is set to 361°C for 90s. Finally, gold-tin soldering is performed, and the gold-tin soldering temperature is set to 280°C. This achieves a three-level temperature gradient from high to low, ensuring that the first two solders will not melt again during subsequent welding, thereby ensuring the stability of the production process. The base plate assembly and the cover plate assembly are sealed in parallel. This process does not require a high-temperature environment, and uses a large current to melt the metal.

[0044] The technical scope of the present invention is not limited to the contents in the above description. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of ​​the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. A double-sided heat dissipation low-resistance CSMD ceramic tube shell, characterized in that: The invention comprises a substrate (1), the upper surface of the substrate (1) is metallized, a sealing ring (2) is welded to the upper surface of the substrate (1), a MOS tube (3) located inside the sealing ring (2) is arranged on the upper surface of the substrate (1), and the D pole of the MOS tube (3) is welded to the metallized surface of the substrate (1), a flat sealing cover plate (5) is welded to the upper surface of the sealing ring (2), and a ceramic plate (4) located above the MOS tube (3) inside the sealing ring (2) is welded to the lower surface of the flat sealing cover plate (5), and the G pole electrode (7) and the S pole electrode (6) on the MOS tube (3) are both connected to the upper surface of the flat sealing cover plate (5).

2. The double-sided heat dissipation low-resistance CSMD ceramic tube shell according to claim 1, characterized in that: The ceramic plate (4) is provided with two cavities, and the S-pole electrode (6) and the G-pole electrode (7) respectively penetrate the two cavities of the ceramic plate (4) and are sealed and welded to the surface of the ceramic plate (4).

3. The double-sided heat dissipation and low-resistance CSMD ceramic tube shell according to claim 2, characterized in that: The G-pole electrode (7) and the S-pole electrode (6) are both configured as electrodes made of tungsten-copper material, specifically W85Cu15.

4. The double-sided heat dissipation and low-resistance CSMD ceramic tube shell according to claim 3, characterized in that: The G-pole electrode (7) and the S-pole electrode (6) are both arranged in a T-shaped structure.

5. The double-sided heat dissipation and low-resistance CSMD ceramic tube shell according to claim 1, characterized in that: The cross-sectional area of ​​the substrate (1) is greater than the cross-sectional area of ​​the MOS tube (3), and the area difference is no greater than one twentieth of the cross-sectional area of ​​the MOS tube (3).

6. The double-sided heat dissipation and low-resistance CSMD ceramic tube shell according to claim 5, characterized in that: A heat sink is welded on the bottom of the substrate (1).

7. The double-sided heat dissipation and low-resistance CSMD ceramic tube shell according to claim 6, characterized in that: The substrate (1) is configured as a plate body made of AlN material, and the ceramic plate (4) is configured as a plate body made of Al2O3 material.

8. The double-sided heat dissipation and low-resistance CSMD ceramic tube shell according to claim 1, characterized in that: The sealing ring (2) and the flat sealing cover plate (5) are both configured as frames made of Kovar material; the sealing ring (2) is specifically configured as 4J29 material, and the flat sealing cover plate (5) is specifically configured as 4J42 material.

9. A process flow of a double-sided heat dissipation low-resistance CSMD ceramic tube shell, applied to a double-sided heat dissipation low-resistance CSMD ceramic tube shell according to claims 1-8, characterized in that: The following steps are involved: S1, the sealing ring (2) is welded to the upper surface of the substrate (1) by means of a sealing ring solder (14) to form a bottom plate assembly, and the flat sealing cover plate (5) is welded to the upper surface of the ceramic plate (4) by means of a cover plate solder (12) to form a cover plate assembly; S2, the MOS tube (3) is welded to the upper surface of the substrate (1) by means of MOS tube solder (13) to form a chip mounting assembly; S3, the S-pole electrode (6) and the G-pole electrode (7) are respectively welded to the upper surface of the MOS tube (3) through the S-pole pre-set solder (9) and the G-pole pre-set solder (11); S4, the flat sealing cover plate (5) is welded parallel to the upper surface of the sealing ring (2) to form a chip packaging assembly; S5. The S-pole electrode (6) and the G-pole electrode (7) are respectively welded to the surface of the ceramic plate (4) by means of the S-pole electrode solder (8) and the G-pole electrode solder (10), thereby completing the welding work.

10. The process flow of a double-sided heat dissipation low-resistance CSMD ceramic tube shell according to claim 9, characterized in that: The sealing ring solder (14) and the cover plate solder (12) are both set as silver-copper solder, specifically Ag72Cu28, the MOS tube solder (13) is set as gold-germanium solder, specifically Au88Ge12, and the S-pole electrode solder (8), the S-pole pre-set solder (9), the G-pole electrode solder (10) and the G-pole pre-set solder (11) are all set as gold-tin solder, specifically Au80Sn20.

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