Metal-ceramic integrated package housing

Abstract

The application discloses a metal-ceramic integrated packaging shell, which comprises a ring frame, a ceramic bottom plate sealed and welded at an opening at the bottom of the ring frame, and a cover plate sealed and welded at an opening at the top of the ring frame; the material thermal conductivity of the ring frame is greater than 140 W / mK, the thermal expansion coefficient of the ring frame changes in a gradient from the top to the bottom of the ring frame, the thermal expansion coefficient of the ring frame at the bottom is consistent with that of the ceramic bottom plate, and the thermal expansion coefficient of the ring frame at the top is consistent with that of the cover plate. The application improves the sealing performance and service life while realizing three-dimensional heat dissipation, increasing the heat dissipation area and improving the heat dissipation capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of packaging devices applied to power hybrid integrated circuits and multi-chip modules, in particular to a metal-ceramic integrated packaging shell. BACKGROUND

[0002] At present, the power circuit ceramic integrated packaging shells used at home and abroad mainly adopt 4J29, 4J34 and other iron-nickel low-expansion coefficient metals as ring frames, adopt iron-nickel alloys as cover plates, and adopt multilayer structures of aluminum oxide as bottom plates, which have low thermal conductivity. Some of them embed metal blocks on the bottom surface for heat conduction, and some of them use metal sheets bonded on the top of the chip for heat dissipation. There are problems of poor heat dissipation, and the heat dissipation channels are single, mainly one-dimensional direction of the bottom surface or the top surface. It is difficult to meet the heat dissipation requirements of larger power and higher integrated circuits. And the single heat dissipation channel also hinders the high integration of the board-level packaging.

[0003] At the same time, since the packaging shell is mainly sealed and welded by different materials, due to the inconsistent thermal expansion coefficients between different materials, the alternating temperature changes during work often cause changing thermal stress at the weld, leading to thermal fatigue failure and cracks, resulting in loss of sealing and functional failure. SUMMARY

[0004] In order to solve the problems of single heat dissipation direction, limited heat dissipation capacity and thermal fatigue failure existing in the prior art, the present application provides a metal-ceramic integrated packaging shell with three-dimensional heat dissipation capacity and good packaging sealing performance.

[0005] The technical scheme of the present application is as follows:

[0006] A metal-ceramic integrated packaging shell, comprising a ring frame, a ceramic bottom plate sealed and welded at the bottom opening of the ring frame, and a cover plate sealed and welded at the top opening of the ring frame.

[0007] The material thermal conductivity of the ring frame (2) is greater than 140 W / mK, and the thermal expansion coefficient thereof changes in a gradient along the axis (S) direction of the ring frame from one end to the other end:

[0008] At the cover plate end of the ring frame (2) and the cover plate (1) sealed and welded, the thermal expansion coefficient of the ring frame (2) ranges from (21-23) x 10 -6 / ℃;

[0009] At the bottom plate end of the ring frame (2) and the ceramic bottom plate (3) sealed and welded, the thermal expansion coefficient of the ring frame (2) ranges from (6.8-12) x 10 -6 / ℃;

[0010] The coefficient of thermal expansion of the ring frame (2) is in the range of (12-21) x 10-6 / ℃ at the transition section between the cover plate end and the bottom plate end. -6 / ℃.

[0011] Preferably, at least one heat dissipation channel is arranged on the outer surface of the ring frame in the circumferential direction, and the heat dissipation channel is a groove structure arranged in the circumferential direction of the ring frame.

[0012] Preferably, the ceramic bottom plate is provided with a side wall structure on the surface sealed and welded with the ring frame, and the side wall structure is a boss surrounding the surface.

[0013] Specifically, the material of the ceramic bottom plate is an aluminum nitride multilayer structure, and the materials of the ring frame and the cover plate are both aluminum-based composite materials.

[0014] Specifically, the ring frame and the cover plate are connected and sealed by laser welding, and the ring frame and the cover plate are connected and sealed by brazing.

[0015] In the technical scheme of the present application, the ceramic bottom plate, the cover plate and the ring frame are all good heat dissipation materials, forming a three-dimensional heat dissipation effect on the internal packaged chip circuit. Compared with the prior art, the heat dissipation capacity is improved by increasing the heat dissipation direction, and at the same time, the outer surface of the ring frame is optimized, and a heat dissipation channel is arranged on the outer surface. The heat dissipation channel increases the contact area between the ring frame and the air, so that the heat dissipation capacity of the ring frame is improved compared with the prior art. At the same time, by designing the gradient material of the coefficient of thermal expansion, improving the welding process, using laser welding between the ceramic bottom plate and the ring frame, and using brazing between the ring frame and the cover plate, the sealing performance of the packaged circuit is ensured while the heat dissipation capacity is improved and the welding complexity and cost are reduced. Therefore, the present application has the characteristics of multiple heat dissipation channels, large heat dissipation area, strong heat dissipation capacity, and good sealing performance. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a lateral cross-sectional view of the present application;

[0017] Figure 2 It is a cross-sectional view of the ring frame of the present application.

[0018] In the figure:

[0019] 1 cover plate; 2 ring frame; 3 ceramic bottom plate;

[0020] 21 groove; 31 side wall;

[0021] W1 first weld; W2 second weld;

[0022] 2UP cover plate end; 2MD transition end; 2DN bottom plate end. DETAILED DESCRIPTION

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] like Figure 1 The integrated metal-ceramic encapsulation shell shown includes a ceramic base plate 3, a ring frame 2, and a cover plate 1. The ring frame 2 is made of an aluminum-based composite material with a thermal conductivity greater than 140 W / mK, ensuring good basic heat dissipation capacity. Four grooves 21 are circumferentially arranged on the outer side of the ring frame 2. The grooves 21 increase the contact area between the outer side of the ring frame 2 and the air, thereby accelerating heat exchange between the ring frame 2 and the outside air and improving heat dissipation capacity.

[0025] The coefficient of thermal expansion of the ring frame 2 varies along the axial direction S. Specifically, the ring frame substrate is made of aluminum alloy, and reinforcing elements are added through a melt infiltration process to adjust the coefficient of thermal expansion of the substrate material. Specifically, the cover plate end 2UP, where the ring frame 2 connects to the cover plate 1, is made of aluminum alloy with a silicon content of less than 8%. The material composition of the cover plate end is similar to that of the cover plate material, which is beneficial for laser welding of the cover. During laser welding, the remelted metal in the weld bead flows easily and is less prone to cooling cracks, which is conducive to forming a sealed weld. Its coefficient of thermal expansion ranges from (21-23)×10⁻⁶. -6 / ℃. The base plate end 2DN, where the ring frame 2 connects to the ceramic base plate 3, is a 50%-70% silicon carbide-based metal composite material with a thermal expansion coefficient ranging from (6.8-12)×10⁻⁶. -6 The coefficient of thermal expansion is close to that of ceramic substrate materials used in widely used power circuits, allowing for thermal matching and reducing mismatch stress during welding with the ceramic base plate. Simultaneously, the material boasts high mechanical strength, ensuring good structural strength. The transition section 2MD between the cover plate end 2UP and the base plate end 2DN of the ring frame 2 is made of a silicon-aluminum alloy with a silicon content of 10-30%. Its coefficient of thermal expansion falls between that of the cover plate end 2UP and the base plate end 2DN, and is (12-21)×10. -6The transition of the components of the upper metal and the lower metal and the thermal expansion coefficient reduces the internal stress of the material after being heated, and by finely controlling the porosity of the preform used during the infiltration and coordinating the process control of the infiltration process, it is ensured that the material components inside the cover plate end 2UP, the transition end 2MD and the bottom plate end 2DN of the ring frame change with the height during the infiltration, and the linear expansion coefficient at the boundary of each part does not change suddenly, but gradually transitions, reducing the thermal stress generated at the junction of the cover plate end 2UP, the transition end 2MD and the bottom plate end 2DN inside the ring frame after being heated.

[0026] The above gradient design of the thermal expansion coefficient of the ring frame can ensure that the size change of the materials on both sides of the weld due to temperature change is consistent during the welding process and the cooling process after welding, thereby avoiding the problems of weld cracking, potential seam or the existence of welding stress at the weld that cannot be released to reduce the welding strength, resulting in loss of sealing. Weld cracking and loss of sealing can cause product scrap, and the existence of welding stress can cause potential risks of weld cracking under external force or cracking when the temperature changes during subsequent use. At the same time, since the metal-ceramic integrated packaging shell needs to dissipate heat from the internal circuit, its working environment changes alternately between hot and cold, and the other important role of matching the thermal expansion coefficients of the materials in the above two welding areas is to avoid thermal fatigue failure at the weld and the resulting loss of sealing and functional failure due to inconsistent thermal expansion coefficients of the materials in the long-term temperature change environment.

[0027] At least one heat dissipation groove 21 is formed on the outer circumferential surface of the ring frame 2, which increases the heat dissipation area of the outer circumferential surface of the ring frame 2 and the surrounding air, thereby achieving the effect of improving the heat dissipation capacity. The bottom plate cross section of the ring frame 2 and the ceramic bottom plate 3 is trapezoidal, which improves the welding area during welding, strengthens the welding strength, and ensures the welding stability.

[0028] The ceramic bottom plate 3 is an aluminum nitride multilayer structure, which is provided with a raised side wall 31 around the surface edge of the ring frame welding, the side wall 31 strengthens the ceramic bottom plate 3 and improves the bending and torsion resistance of the bottom plate. The ceramic bottom plate 3 integrates the conventional metal shell packaging circuit module and the circuit substrate, integrates the circuit and the packaging element carrier, the inner and outer surfaces of the bottom plate are provided with a metalized circuit pattern, nickel plating, gold plating, the intermediate layer of the ceramic is provided with an internal circuit pattern and a via hole for welding chips, resistors, capacitors and other elements, to realize the connection and transmission of signals, currents and voltages, and also as the input and output of the internal and external signals, currents and voltages of the circuit, which is one of the mechanical bearing surfaces of the circuit elements and the heat dissipation surface of the circuit; the integrated ceramic bottom plate 3 is preferably made of high-temperature co-fired multilayer high-thermal-conductivity aluminum nitride ceramic, the thermal conductivity of the aluminum nitride material is greater than 170 W / mK, the bottom plate adopts aluminum nitride ceramic material, has high thermal conductivity, light weight, reliable mechanical strength, and can integrate the circuit substrate and the shell bottom plate by using high-temperature co-fired multilayer process.

[0029] The cover plate 1 and the ring frame 2 are made of aluminum-based composite material, which has high thermal conductivity, low thermal expansion coefficient, low density, good forming performance and excellent welding performance. The thermal conductivity of the aluminum-based composite material is greater than 140 W / mK, and its thermal expansion coefficient can be adjusted by process to form the material with the gradient change of the thermal expansion coefficient as described above, so it is the preferred material for the ring frame. Of course, it should be noted that the aluminum-based composite material is the preferred material in actual production process, and other materials with high thermal conductivity and suitable thermal expansion coefficient can also be used as alternative solutions for the ring frame material, such as copper-based composite material.

[0030] Since the material of the ring frame 2 is aluminum-based composite material and the material of the ceramic bottom plate 3 is aluminum nitride multilayer structure, the two materials are different, and the general welding process has poor combination, so the brazing process must be used. The filler metal filled in the second weld W2 melts at high temperature and combines with the materials of the ring frame 2 and the ceramic bottom plate 3 to realize the sealing of the weld and meet the structural strength requirements. At the first weld W1 between the ring frame 2 and the cover plate 1, since the materials of the two are the same, laser process can achieve the required bonding force, and laser welding has the characteristics of simple process and low cost.

[0031] It is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0032] Furthermore, it should be understood that although the description is made according to the embodiments, not every embodiment contains only one independent technical solution, and the description is made in this way only for the sake of clarity, and the person skilled in the art should consider the description as a whole, and the technical solutions in each embodiment can also be combined appropriately to form other embodiments that the person skilled in the art can understand.

Claims

1. A cermet integrated package housing, characterized by, It comprises a ring frame (2), a ceramic bottom plate (3) sealed and welded at one end opening of the ring frame and a cover plate (1) sealed and welded at the other end opening of the ring frame. The material of the ring frame (2) has a thermal conductivity greater than a coefficient of thermal expansion which varies in a gradient manner from one end to the other along the direction of the ring frame axis (S): In the cover plate end (2UP) where the ring frame (2) is seal-welded to the cover plate (1), the coefficient of thermal expansion of the ring frame (2) is in the range of (21-23) x 10 -6 / ℃; In the bottom plate end (2DN) where the ring frame (2) is seal-welded to the ceramic bottom plate (3), the coefficient of thermal expansion of the ring frame (2) is in the range of (6.8-12) x 10 -6 / ℃; In the transition section (2MD) of the ring frame (2) between the cover plate end and the bottom plate end, the coefficient of thermal expansion of the ring frame (2) ranges from (12-21) x 10 -6 / ℃; The ceramic bottom plate (3) is an aluminum nitride multilayer structure, the material of the ring frame (2) and the cover plate (1) is aluminum-based composite material; the transition section (2MD) of the ring frame (2) is silicon aluminum composite material with silicon content, and the bottom plate end (2DN) of the ring frame (2) is aluminum-based composite material with silicon carbide component; The cover plate end (2UP) of the ring frame (2) connected with the cover plate (1) is aluminum alloy material with silicon content less than 8%, the bottom plate end (2DN) of the ring frame (2) connected with the ceramic bottom plate (3) is 50-70% silicon carbide component metal composite material, and the transition section (2MD) between the cover plate end (2UP) and the bottom plate end (2DN) of the ring frame (2) adopts silicon aluminum alloy with silicon content of 10-30%.

2. The cermet-integrated package enclosure of claim 1, wherein, At least one heat dissipation channel is arranged on the outer side of the ring frame (2) in the circumferential direction, and the heat dissipation channel is a groove (21) arranged in the circumferential direction of the ring frame (2).

3. The cermet integrated package enclosure of any of claims 1-2, wherein, The ring frame (2) and the cover plate (1) are connected by laser welding sealing, and the ring frame (2) and the ceramic bottom plate (3) are connected by brazing sealing.

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