Aluminum oxide ceramic substrate-aluminum silicon carbide heat sink substrate packaging shell and preparation method thereof

Abstract

The invention belongs to the technical field of electronic packaging, and particularly relates to an aluminum oxide ceramic substrate-aluminum silicon carbide heat sink substrate packaging shell and a preparation method thereof. The device comprises a sealing ring, a ceramic substrate and a heat sink bottom plate used for heat dissipation which are sequentially connected from top to bottom, the ceramic substrate is made of aluminum oxide, and the heat sink bottom plate is made of aluminum silicon carbide; a plurality of mounting holes are formed in the heat sink base plate, annular aluminum-silicon alloy is embedded in the mounting holes, and threads are formed in the inner wall of the aluminum-silicon alloy. According to the invention, the problem of thermal adaptation of the aluminum oxide ceramic substrate to the heat sink bottom plate can be solved, and the requirement of the packaging shell on the internal air tightness of the cavity can be met. Meanwhile, an aluminum-silicon inlaying mode is adopted at the mounting holes in the aluminum-silicon carbide bottom plate, so that the processing yield of the heat sink bottom plate is greatly improved, and the stability of the packaging shell on an external module is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic packaging, and in particular relates to an alumina ceramic substrate-aluminum silicon carbide heat sink bottom plate packaging shell and a preparation method thereof. Background Art

[0002] With the continuous development of the electronic packaging industry, the carrying and protection methods of chips and devices are diverse. In order to meet the carrying and protection of various devices, new ceramic-metal integrated shells are widely used in military electronics, aerospace and other fields. In integrated circuits, the heat dissipation requirements of chips and components are getting higher and higher, so the packaging shells to protect chips and components are also diverse.

[0003] As a carrier for the installation, sealing and protection of internal chips, the package shell plays an irreplaceable role. Generally, the connection between electronic circuit chips and various components also transmits signals through intermediate media to achieve the connectivity of internal and external circuits and the functional role of chips. The positioning and installation of the package shell in the module circuit is not only crucial, but also related to the reliability and stability of the circuit.

[0004] The existing package shell needs to be installed in the circuit for use. For such large-area installation, screw installation is the most convenient and reliable method. The drilling and tapping process of the aluminum silicon carbide heat sink base with threaded holes is an extremely important part, which determines the stability of the entire device and the reliability of the circuit. However, due to the high brittleness of aluminum silicon carbide, when processing the heat sink base, especially when opening the threads, the threads will collapse, resulting in a low production yield and increased preparation costs; and the prepared package shell has low airtightness. Summary of the invention

[0005] In order to overcome the defects in the prior art, the present invention provides an alumina ceramic substrate-aluminum silicon carbide heat sink bottom plate packaging shell and a preparation method thereof. The packaging shell of the present invention has high air tightness, and the heat sink bottom plate is easy to open threaded holes.

[0006] To achieve one of the above purposes, the present invention adopts the following technical solution:

[0007] An alumina ceramic substrate-aluminum silicon carbide heat sink bottom plate packaging shell comprises a sealing ring, a ceramic substrate and a heat sink bottom plate for heat dissipation which are connected in sequence from top to bottom. The ceramic substrate is alumina and the heat sink bottom plate is aluminum silicon carbide. A plurality of mounting holes are provided on the heat sink bottom plate, and an annular aluminum silicon alloy is embedded in the mounting holes. The inner wall of the aluminum silicon alloy is provided with threads.

[0008] Preferably, the sealing ring and the ceramic substrate, the ceramic substrate and the heat sink bottom plate, and the aluminum silicon alloy and the mounting hole are all welded by gold-tin alloy solder.

[0009] Preferably, the heat sink bottom plate is protruding upwards and is provided with two bosses for mounting the chip, and the ceramic substrate is provided with two through cavities, the tops of the bosses pass through the through cavities, and the shapes of the bosses are adapted to the sizes of the through cavities.

[0010] Preferably, a blind groove is embedded inwardly at the bottom of the non-installation area of ​​the heat sink bottom plate.

[0011] Preferably, the sealing ring is made of Kovar alloy.

[0012] Preferably, the plate surface size of the ceramic substrate is 33.0 mm×31.0 mm; the ring surface size of the sealing ring is 30.4 mm×29.4 mm; and the maximum diameter of the heat sink bottom plate is 76.0 mm.

[0013] Preferably, the surface of the sealing ring, the surface of the ceramic substrate and the surface of the heat sink bottom plate are all plated with nickel layer and gold layer, the thickness of the nickel layer is 2.54-11.43um, the thickness of the gold layer is ≥1.3um, and the nickel layer is plated first and then the gold layer, which not only meets the gold-tin welding requirements but also can be used for corrosion protection.

[0014] To achieve the second of the above objectives, the present invention provides a method for preparing an alumina ceramic substrate-aluminum silicon carbide heat sink bottom plate packaging shell according to any one of claims 1 to 7, characterized in that it comprises the following steps:

[0015] S1. The sealing ring plated with nickel-gold and the ceramic substrate plated with nickel-gold are welded into a separate body by a reflow process using gold-tin alloy solder;

[0016] S2, using gold-tin alloy solder to vacuum weld the split body to the heat sink bottom plate;

[0017] S3. Use gold-tin alloy solder to embed a ring-shaped aluminum-silicon alloy into the mounting hole on the heat sink bottom plate at a embedding temperature of 280-300 degrees, and then tap the inner wall of the aluminum-silicon alloy to form a threaded hole.

[0018] Preferably, the preparation method of the heat sink bottom plate is: pressure-infiltrating a porous SiC ceramic piece into aluminum liquid by a pressure infiltration method to obtain an aluminum silicon carbide heat sink bottom plate.

[0019] Preferably, the method for preparing the heat sink bottom plate is: preparing the aluminum silicon carbide heat sink bottom plate by using aluminum powder and SiC powder through powder metallurgy.

[0020] The advantages of the present invention are:

[0021] (1) The present invention can not only solve the problem of thermal adaptation of the alumina ceramic substrate to the heat sink bottom plate, but also meet the requirements of the encapsulation shell for the airtightness of the cavity. At the same time, the mounting holes on the aluminum silicon carbide bottom plate are inlaid with aluminum silicon, which greatly improves the processing yield of the heat sink bottom plate and ensures the stability of the encapsulation shell on the external module, thus achieving stable and reliable welding and installation of large-size alumina ceramic substrates.

[0022] (2) In order to adapt to the alumina ceramic substrate, the present invention selects lightweight aluminum silicon carbide as the heat sink bottom plate for heat dissipation. The thermal expansion coefficients of the two are close, which meets the requirements of thermal matching, improves the yield and reliability of the integrated packaging shell in the circuit module, and has a reasonable and reliable structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a top view schematic diagram of the present invention.

[0024] Figure 2 It is a schematic diagram of the AA cross-sectional structure of the present invention.

[0025] Figure 3 It is a bottom view structural schematic diagram of the present invention.

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

[0027] 1-sealing ring, 2-ceramic substrate, 21-through cavity, 3-heat sink bottom plate, 31-boss, 32-mounting hole, 33-blind groove, 4-aluminum silicon alloy. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0029] like Figure 1-3 As shown, it includes an alumina ceramic substrate 2, a sealing ring 1, and an aluminum silicon carbide heat sink bottom plate 3. The sealing ring 1 plated with nickel gold is welded to the alumina ceramic substrate 2 by gold-tin soldering, and then integrally vacuum welded to the aluminum silicon carbide heat sink bottom plate 3 to form an integrated packaging shell. Two through cavities 21 are provided on the ceramic substrate 2, and two small bosses 31 are provided on the heat sink bottom plate 3 at the corresponding positions. The bosses 31 are the carriers of the high-power chip. The chip is interconnected with other external components through the circuit inside the alumina ceramic substrate 2.

[0030] Specifically, the ceramic substrate 2, the sealing ring 1, and the heat sink bottom plate 3 all need to be gold-plated. The sealing ring 1 is first welded to the ceramic substrate 2 through a reflow soldering process to form a separate body. In order to ensure the welding void rate on the lower surface of the ceramic substrate 2, the sealing ring 1-alumina ceramic substrate 2 is separated and vacuum gold-tin soldered to the heat sink bottom plate 3 to achieve airtightness.

[0031] Furthermore, a plurality of mounting holes 32 are provided on the heat sink bottom plate 3. The ceramic substrate 2 is made of alumina material, the sealing ring 1 is made of Kovar (4J29), the heat sink bottom plate 3 is made of aluminum silicon carbide (SiCp / Al) material, and a ring-shaped aluminum silicon alloy 4 is embedded in the mounting hole 32, and the inner wall of the aluminum silicon alloy 4 is provided with threads.

[0032] Furthermore, the integrated package shell is a three-layer structure of sealing ring 1-alumina ceramic substrate 2-aluminum silicon carbide heat sink bottom plate 3. The aluminum silicon carbide heat sink bottom plate 3 is provided with an M10.0 mounting hole 32 for installing the RF connector. The ceramic substrate 2 is provided with two through cavities 21. The two bosses 31 on the upper surface of the heat sink bottom plate 3 correspond to the two through cavities 21. The aluminum silicon carbide heat sink bottom plate 3 is provided with multiple M2.0 threaded mounting holes 32 for the integrated shell to be installed on the external module. The M2.0 and M10.0 mounting holes 32 are processed by embedding aluminum silicon.

[0033] The ring surface size of the sealing ring 1 is 30.4 mm × 29.4 mm; the plate surface size of the ceramic substrate 2 is 33.0 mm × 31.0 mm, with a 20-layer wiring structure; the diameter size of the heat sink bottom plate 3 is 76.0 mm. Figure 1 As shown, the inwardly recessed groove at the top of the heat sink bottom plate 3 can be used to reduce weight; Figure 3 As shown in the figure, the "C" structure is a blind groove 33 that is recessed inward at the bottom of the heat sink bottom plate 3. The shape is to avoid the large square ceramic substrate 2 above, which is convenient for reducing the weight of the entire package shell. The groove and the blind groove 33 are not connected. The surface of the sealing ring 1, the surface of the ceramic substrate 2 and the surface of the heat sink bottom plate 3 are all plated with a nickel layer and a gold layer. The thickness of the nickel layer is 2.54-11.43um, and the thickness of the gold layer is ≥1.3um. The nickel layer is plated first and then the gold layer.

[0034] like Figure 1 As shown, the two circles on the left side of the heat sink bottom plate 3 are threaded through holes for placing radio frequency connectors.

[0035] A method for preparing an alumina ceramic substrate-aluminum silicon carbide heat sink bottom plate packaging shell comprises the following steps:

[0036] S1, welding the sealing ring 1 plated with nickel-gold and the ceramic substrate 2 plated with nickel-gold into a separate body by a reflow soldering process using gold-tin alloy solder;

[0037] S2, using gold-tin alloy solder to vacuum weld the split body to the heat sink bottom plate 3;

[0038] S3. Use gold-tin alloy solder to embed a ring-shaped aluminum-silicon alloy 4 into the mounting hole 32 on the heat sink bottom plate 3 at a embedding temperature of 280-300 degrees, and then tap the inner wall of the aluminum-silicon alloy 4 to form a threaded hole.

[0039] The preparation method of the heat sink bottom plate 3 is as follows: a porous SiC ceramic piece is pressure-infiltrated into aluminum liquid by a pressure infiltration method to obtain an aluminum silicon carbide heat sink bottom plate 3 .

[0040] The preparation method of the heat sink bottom plate 3 is as follows: aluminum powder and SiC powder are prepared by powder metallurgy to obtain the aluminum silicon carbide heat sink bottom plate 3 .

[0041] The above are only preferred embodiments of the present invention and are 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 protection scope of the present invention.

Claims

1. An alumina ceramic substrate-aluminum silicon carbide heat sink bottom plate packaging shell, characterized in that: The invention comprises a sealing ring (1), a ceramic substrate (2) and a heat sink bottom plate (3) for heat dissipation, which are connected in sequence from top to bottom, wherein the ceramic substrate (2) is made of aluminum oxide, and the heat sink bottom plate (3) is made of aluminum silicon carbide; a plurality of mounting holes (32) are provided on the heat sink bottom plate (3), and an annular aluminum silicon alloy (4) is embedded in the mounting holes (32); the inner wall of the aluminum silicon alloy (4) is provided with a thread.

2. According to the alumina ceramic substrate-aluminum silicon carbide heat sink bottom plate packaging shell according to claim 1, the sealing ring (1) and the ceramic substrate (2), the ceramic substrate (2) and the heat sink bottom plate (3), and the aluminum silicon alloy (4) and the mounting hole (32) are all welded by gold-tin alloy solder.

3. The alumina ceramic substrate-aluminum silicon carbide heat sink bottom plate packaging shell according to claim 1, characterized in that: The heat sink bottom plate (3) is protruding upward and is provided with two bosses (31) for mounting a chip. The ceramic substrate (2) is provided with two through cavities (21). The tops of the bosses (31) pass through the through cavities (21), and the shape of the bosses (31) is adapted to the size of the through cavities (21).

4. The alumina ceramic substrate-aluminum silicon carbide heat sink bottom plate packaging shell according to claim 1, characterized in that: A blind groove (33) is embedded inwardly at the bottom of the non-installation area of ​​the heat sink bottom plate (3).

5. The alumina ceramic substrate-aluminum silicon carbide heat sink bottom plate packaging shell according to claim 1, characterized in that: The sealing ring (1) is made of Kovar alloy.

6. The alumina ceramic substrate-aluminum silicon carbide heat sink bottom plate packaging shell according to claim 1, characterized in that: The plate surface size of the ceramic substrate (2) is 33.0 mm×31.0 mm; the ring surface size of the sealing ring (1) is 30.4 mm×29.4 mm; and the diameter of the heat sink bottom plate (3) is 76.0 mm.

7. The alumina ceramic substrate-aluminum silicon carbide heat sink bottom plate packaging shell according to claim 1, characterized in that: The surface of the sealing ring (1), the surface of the ceramic substrate (2) and the surface of the heat sink bottom plate (3) are all plated with a nickel layer and a gold layer, the thickness of the nickel layer is 2.54-11.43 um, and the thickness of the gold layer is ≥1.3 um.

8. A method for preparing an alumina ceramic substrate-aluminum silicon carbide heat sink bottom plate packaging shell according to any one of claims 1 to 7, characterized in that: The steps include: S1, welding a sealing ring (1) plated with nickel-gold and a ceramic substrate (2) plated with nickel-gold into a separate body by a reflow soldering process using a gold-tin alloy solder; S2, using gold-tin alloy solder to vacuum weld the split body to the heat sink bottom plate (3); S3. Use gold-tin alloy solder to embed a ring-shaped aluminum-silicon alloy (4) into the mounting hole (32) on the heat sink bottom plate (3). The embedding temperature is 280-300 degrees. Then, the inner wall of the aluminum-silicon alloy (4) is tapped to form a threaded hole.

9. The method for preparing the alumina ceramic substrate-aluminum silicon carbide heat sink bottom plate packaging shell according to claim 8, characterized in that: The preparation method of the heat sink bottom plate (3) comprises: infiltrating a porous SiC ceramic piece into aluminum liquid by pressure infiltration to obtain an aluminum silicon carbide heat sink bottom plate (3).

10. The method for preparing the alumina ceramic substrate-aluminum silicon carbide heat sink bottom plate packaging shell according to claim 8, characterized in that: The preparation method of the heat sink bottom plate (3) is as follows: aluminum powder and SiC powder are prepared by powder metallurgy to obtain the aluminum silicon carbide heat sink bottom plate (3).

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