An integrated circuit package structure and method of assembling the same

Abstract

The application discloses an integrated circuit packaging structure and an assembling method thereof. The integrated circuit packaging structure comprises a metal shell (1), wherein an opening groove (12) of the metal shell is provided with a stepped opening (11); a metal insulator (2) comprises a nanometer ceramic aluminum alloy base (21) provided with a group of mounting through holes (22), an outer contour edge of the nanometer ceramic aluminum alloy base is provided with a stepped opening (23), the stepped opening (23) is matched with the stepped opening in shape, an insulating layer (24) of triple structure alumina is connected to a surface of the nanometer ceramic aluminum alloy base, a metallization layer (25) is connected to the insulating layer on a surface of the stepped opening and an inner wall of the mounting through hole; a group of pins (3) are provided with flanges (31), and each pin is sealedly welded with the metal insulator through the flange and the metallization layer on the inner wall of the mounting through hole; the stepped opening is connected with the stepped opening, and the metal shell is sealedly welded with the metal insulator; and the shell and a PCB (4) are assembled by adopting a radial welding method. The application can improve the high-impact resistance of the hybrid integrated circuit in use.

Description

Technical Field

[0001] This invention relates to the field of hybrid integrated circuit technology, and more specifically to an integrated circuit packaging structure and its assembly method. Background Technology

[0002] A typical packaging form for hybrid integrated circuits is the metal-cased package. Specifically, a circuit substrate is first fabricated, and then various components are assembled and interconnected on the substrate. The substrate is typically assembled to the metal casing using adhesive (or soldering) methods, and electrical connections between the substrate and the outer leads of the package are achieved through bonding. One conventional metal-cased package is as follows: Figure 1 As shown: A glass insulator a3 is sintered between the outer lead a1 and the base a2 of the outer casing. The glass insulator a3 serves two purposes: firstly, it insulates the outer lead from the metal casing; secondly, it maintains the hermeticity of the entire casing. A major problem with this conventional metal casing encapsulation is that the brittle nature of the glass insulator a3 directly results in its low strength. Especially under high-intensity mechanical impact, the glass insulator a3 mounted on the circuit board is prone to breakage. These fragments can form movable foreign objects inside the circuit, directly causing product performance and quality problems.

[0003] In response to this problem, the following suggestions are made: Figure 2 The existing solution shown is to use ceramic insulators instead of glass insulators. The inner wall of the ceramic insulator has a first metallization layer b1, and the outer wall has a second metallization layer b2. The first metallization layer b1 is used for welding and assembly with the external leads, and the second metallization layer b2 is used for welding with the outer casing base. Using ceramic insulators improves their strength, but ceramic insulators require two welding operations during assembly, resulting in significantly lower assembly efficiency and a more complex process.

[0004] Therefore, the current solution is to use a ceramic strip structure, transforming the individual, discrete ceramic insulator structure into a unified, integrated ceramic insulator structure, such as... Figure 3 As shown, by replacing multiple discrete ceramic insulators with a single ceramic strip body c1 (strip insulator), and by creating metallized through holes in the ceramic strip body c1, it is possible to achieve simultaneous welding of each external lead to the ceramic strip body c1 in one go. This eliminates the separate assembly mode of each independent insulator and the metal shell, significantly reduces the number of welding assembly times, and improves the overall efficiency of insulator assembly.

[0005] However, facing higher requirements for impact and vibration resistance, as well as the heat dissipation and high reliability requirements of power circuits, the use of ceramic strip structures still has the following problems: First, although the local strength at the external leads is higher than that of the original glass material, compared with the original metal structure, the overall strength and toughness of the ceramic strip itself are reduced, and its brittleness is significantly increased. Under higher mechanical impact and vibration environments, the ceramic strip is prone to cracking or even shattering. Second, replacing the original metal part of the shell with a ceramic strip will directly lead to a decrease in heat dissipation performance, which is not conducive to the use of high-power circuits. Third, although the ceramic strip makes the insulator form an integrated structure, it also makes the ceramic strip... A segmented structure is formed between the ceramic strip and the metal housing. Under high impact overload in the Y1 direction, there is a tendency for the circuit metal housing structure mounted on the PCB board to separate from the ceramic strip, and between the ceramic strip and the external leads. This results in the interfaces between the ceramic strip and the metal housing, and between the external leads and the ceramic strip, being subjected to great impact stress, which may lead to cracks or even loosening at the interfaces. Fourth, the welding and assembly of the ceramic strip to the metal housing and the welding and assembly of each external lead to the ceramic strip involves many welding positions. If there is a leak at any one of these positions, it will lead to the airtightness of the entire circuit. Currently, the overall sealing yield of this packaging structure is low.

[0006] Meanwhile, the circuit package housing also needs to be assembled onto the PCB board via external lead insertion. A typical method is to insert the external leads of the housing into the metallized vias of the PCB board, with the circuit housing located on the front side of the PCB board. The external leads pass through the metallized vias and protrude slightly from the back side of the PCB board. Then, solder is used to solder the ends of the external leads to the metallized vias on the back side of the PCB board. The problem with this assembly method is that the solder is only applied to the ends of the external leads. Typically, the solder only partially fills the metallized vias near the back side of the PCB board, leaving the metallized vias near the front side of the PCB board unfilled. It is difficult to ensure that the solder completely fills the space between the external leads and the via walls within the metallized vias, and even more difficult to ensure that the solder travels from the back side of the PCB across the vias to the front side of the PCB to achieve reliable soldering of the external lead roots at the via positions on the front side of the PCB board. As a result, although the ends of the external leads are soldered and assembled at the through holes on the back of the PCB, the roots of the external leads near the front of the PCB are still suspended in the air. The roots of the external leads lack fixed support on the front of the PCB. Under the action of high-intensity lateral impact and vibration parallel to the PCB, the entire circuit will sway significantly, which will have an adverse effect on the stability of the entire circuit structure. The roots of the external leads will also be subjected to significant lateral shear force, which may even lead to the breakage of the packaged external leads.

[0007] Currently, there is an urgent need for an integrated circuit packaging structure and its assembly method to improve the high impact resistance of hybrid integrated circuits during use. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of the prior art described above, and to propose an integrated circuit packaging structure and its assembly method.

[0009] The present invention adopts the following technical solution: an integrated circuit packaging structure, including a metal shell, characterized in that it further includes:

[0010] a. The bottom of the metal shell is provided with opening slots on both sides. The opening slots are through slots that penetrate the bottom of the metal shell. Each opening slot is provided with a stepped slot.

[0011] b. Metal insulator, the metal insulator includes a nano-ceramic aluminum alloy substrate, a set of mounting through holes is provided on the nano-ceramic aluminum alloy substrate, the outer contour edge of the nano-ceramic aluminum alloy substrate is provided with stepped protrusions, the shape of the stepped protrusions matches the shape of the stepped grooves, the surface of the nano-ceramic aluminum alloy substrate is connected with a triple structure alumina insulation layer, and a metallization layer is connected on the insulation layer on the surface of the stepped protrusions and the insulation layer on the inner wall of the mounting through holes.

[0012] c. A set of pins, each pin having a flange, the insulating layer being connected to a pad corresponding to the mounting through hole opening, each pin being sealed and welded to the metal insulator (2) through the flange, the metallization layer of the mounting through hole inner wall, and the pad;

[0013] d. The metal housing 1 is sealed and welded to the metal insulator by matching the shape of the stepped groove and the step protrusion.

[0014] This invention also discloses an assembly method for an integrated circuit packaging structure, characterized by the following steps: S1: A PCB board is provided with metallized pin holes corresponding to the pins on the metal housing, and pin pads are covered on the openings of the metallized pin holes on both sides of the PCB board; on the area of ​​the PCB board where the metal housing is to be installed, a radial metallization layer divided by gap channels is set with the center point of the area between the metallized pin holes as the origin; the gap channel includes a central circular hole at the origin, a first strip gap connected to it and radiating outwards, and a second strip gap with an inner closed end and an outer open end on a portion of the radial metallization layer; wherein, the outer end of the first strip gap is in an open state, and the gap channels are interconnected; the included angle between the center lines of adjacent first strip gaps and the included angle between the center lines of adjacent first and second strip gaps are both 22.5°;

[0015] S2: Apply solder paste to the surface of the pin pads, the pin hole walls, and the surface of the radial metallization layer. Place ceramic pads on the outer edges of both ends of the radial metallization layer, corresponding to the inner edges of both ends of the bottom of the metal housing. The thickness of the ceramic pads is smaller than the thickness of the solder paste applied to the surface of the radial metallization layer. When the solder paste printing thickness is d0, the solder thickness decreases to d after the organic components in the solder paste overflow into the gap channel during soldering. The area of ​​the solder paste on the surface of the radial metallization layer is S0. Then, the thickness of the ceramic pads is d1 = 0.85d ~ 0.9d, and the design value of the gap channel area is S = (d0 - d)S0 / d1.

[0016] S3: Insert the pins into the corresponding metallized pin holes, place the bottom ends of the metal housing on the ceramic pads on both sides, and ensure that the bottom of the metal housing is in direct contact with the solder paste on the surface of the radial metallized layer; after confirming the position of the metal housing, perform reflow soldering, remove the ceramic pads after soldering, and perform post-soldering cleaning to remove any organic components that have overflowed from the solder paste.

[0017] The beneficial effects of this invention are as follows: 1. The metal insulator using nano-ceramic aluminum alloy as the matrix can significantly improve the overall strength and toughness of the insulator itself, and can withstand higher mechanical impact and vibration environments, while also having better thermal conductivity.

[0018] 2. The metal insulator and the metal housing adopt a stepped interlocking structure and a flange structure for the pins. Under high impact overload in the Y1 direction, the relative separation tendency between the integrated circuit metal housing and the insulator, and between the insulator and the pins is eliminated. At the same time, the effective welding area of ​​each is increased, which can significantly improve the overall sealing performance of the package structure.

[0019] 3. Solder paste is applied to the metallized hole pads on both sides of the PCB board and extends through the inner wall of the metallized lead holes on the PCB board. This enables complete soldering of the integrated circuit leads to the lead holes and their front and back pads on the PCB board, avoiding the problem of lead roots being suspended near the PCB board and the integrated circuit mounting side. This eliminates circuit shaking during strong impacts and vibrations, and improves the stability of the circuit package structure. Combined with the radial metallized layer soldering structure between the metal shell and the PCB board, it prevents the external leads from being subjected to shearing forces during strong impacts and vibrations.

[0020] 4. A welding structure is set between the metal shell and the PCB, which can significantly enhance the overall packaging structure strength of the circuit and effectively improve the heat dissipation performance of the circuit, which is beneficial for the use of high-power circuits. The structural design of the position, angle, area and other aspects of the first and second strip gaps ensures sufficient welding area while also ensuring that solder paste residue can be effectively discharged, thereby ensuring the reliability of welding. Attached Figure Description

[0021] Figure 1 This is a structural diagram of existing technology. Figure 1 ; Figure 2 This is a structural diagram of existing technology. Figure 2 ;

[0022] Figure 3 This is a structural diagram of existing technology. Figure 3 ;

[0023] Figure 4 These are front and top view structural schematic diagrams of the present invention;

[0024] Figure 5 This is a schematic diagram of the metal casing structure;

[0025] Figure 6 yes Figure 5 A partial sectional view of AA;

[0026] Figure 7 This is a schematic diagram of the structure of a metal insulator;

[0027] Figure 8 This is a schematic diagram of the pin structure;

[0028] Figure 9 This is a structural diagram of the mating surfaces of the PCB board.

[0029] Explanation of reference numerals in the attached drawings: 1. Metal housing; 11. Stepped groove; 12. Opening groove; 2. Metal insulator; 21. Nano-ceramic aluminum alloy substrate; 22. Mounting through hole; 23. Stepped protrusion; 24. Insulating layer; 25. Metallization layer; 26. Pad; 3. Lead; 31. Flange; 4. PCB board; 41. Radial metallization layer; 41a. Central circular hole; 41b. First strip gap; 41c. Second strip gap; 42. Metallized lead hole; 43. Lead pad; 5. Ceramic pad; 6. Circuit board; 7. Bonding wire. Detailed Implementation

[0030] To make the present invention clearer, an integrated circuit packaging structure and its assembly method according to the present invention will be further described below with reference to the accompanying drawings. The specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0031] like Figure 4 As shown, an integrated circuit high-impact package structure includes: a metal housing 1, as... Figures 4 to 6 As shown, the metal casing 1 is a rectangular casing without a top cover and with a bottom. On both sides of the bottom of the metal casing 1, a strip-shaped opening groove 12 is symmetrically provided. The opening groove 12 is a rectangular through groove that penetrates the bottom of the metal casing 1. The opening groove 12 is provided with a stepped groove 11.

[0032] Two strip-shaped metal insulators 2, as shown Figure 4 , Figure 7 As shown, the metal insulator 2 includes a rectangular nano-ceramic aluminum alloy substrate 21. The nano-ceramic aluminum alloy substrate 21 has a set of mounting through holes 22. The outer contour edge of the nano-ceramic aluminum alloy substrate 21 has stepped protrusions 23. The shape of the stepped protrusions 23 matches the shape of the stepped grooves 11 and can form an interlocking fit. The surface of the nano-ceramic aluminum alloy substrate 21 is connected to a triple-structured alumina insulating layer 24. A TiNiAu metallization layer 25 is connected to the surface of the insulating layer 24 of the stepped protrusions 23. A gold-plated metallization layer 25 is connected to the insulating layer 24 on the inner wall of the mounting through holes 22. Circular gold-plated pads 26 are connected to the insulating layer 24 at both ends of the mounting through holes 22. The pads 26 correspond to the positions of the mounting through holes 22 and are electrically connected to the metallization layer 25 of the mounting through holes 22. The insulating layer 24 is fabricated into a triple-structured insulating alumina layer through anodizing, exhibiting excellent insulation properties. The specific electrolytes used in the triple-structure anodizing process are boric acid electrolyte, sulfuric acid electrolyte, and boric acid electrolyte, with appropriate process parameters selected based on thickness and insulation performance requirements. The nano-ceramic aluminum alloy is a prior art technology, produced using an in-situ self-generation method of nano-alumina ceramic particles; the triple-structure anodizing process is also a prior art technology.

[0033] A set of pins 3, such as Figure 4 , Figure 8 As shown, pin 3 is a thin rod, and a circular flange 31 is provided on the upper part of pin 3. The projected area of ​​flange 31 is adapted to match the area of ​​pad 26.

[0034] In this embodiment, solder paste is first applied to the metallization layer 25 of the stepped groove 11, the metallization layer 25 of the stepped protrusion 23, the metallization layer 25 of the mounting through hole 22 wall, and the surface of the pad 26. Then, the metal insulator 2 is mounted on the metal housing 1, and the pin 3 is inserted into the mounting through hole 22 with the flange 31 placed on the surface of the pad 26. Finally, the metal insulator 2 and the metal housing 1 are sealed and welded together, the pin 3 and the mounting through hole 22 are sealed and welded together, and the flange 31 and the pad 26 are sealed and welded together. A circuit board 6 is connected to the bottom inner side of the metal housing 1, and the circuit board 6 is connected to the pin 3 through bonding wires 7. Finally, the upper end of the metal housing 1 is sealed to form a complete integrated circuit.

[0035] The assembly method of the packaging structure and PCB board in this embodiment includes the following steps:

[0036] S1: As Figure 9As shown, the PCB board 4 has metallized pin holes 42 corresponding to the pins 3 on the metal housing 1. The openings of the metallized pin holes 42 on both sides of the PCB board 4 are covered with pin pads 43. On the area of ​​the metal housing 1 to be installed on the PCB board 4, a radial metallized layer 41 divided by strip-shaped gap channels is set with the center point of the area between the metallized through holes as the origin. The outer contour of the radial metallized layer 41 is rectangular, and the length of the radial metallized layer 41 is smaller than the length of the bottom of the metal housing 1. The gap channels include a central circular hole 41a at the origin, a first strip gap 41b connected to it and radiating outwards, and a second strip gap 41c with a closed inner end and an open outer end on a part of the radial metallized layer 41. The outer end of the first strip gap 41b is open, and the gap channels are interconnected. The included angle between the center lines of adjacent first strip gaps and the included angle between the center lines of adjacent first and second strip gaps are both 22.5°. The first and second strip gaps are used for the discharge of organic matter in the solder paste during soldering and are channels for the release of organic matter.

[0037] S2: Apply solder paste to the surface of the pin pad 43, the wall of the metallized pin hole 42, and the surface of the radial metallization layer 41. Place ceramic pads 5 on the outer edges of both ends of the radial metallization layer 41, with their positions corresponding to the inner positions of the bottom ends of the metal housing 1. If the subsequent solder paste printing thickness is d0, and the organic components in the solder paste overflow into the gap channel during soldering, the solder thickness will decrease to d. The area of ​​the solder paste on the surface of the radial metallization layer 41 will be S0. Then the thickness of the ceramic pad 5 is: d1 = 0.85d ~ 0.9d, and the design value of the gap channel area is S = (d0 - d)S0 / d1.

[0038] S3: Insert pin 3 into the metallized pin hole 42. Place the bottom ends of the metal housing 1 on the ceramic pads 5 on both sides. The bottom of the metal housing 1 is in direct contact with the solder paste on the surface of the radial metallization layer 41. After the position of the metal housing 1 is adjusted and confirmed, reflow soldering is performed to ensure that the bottom end of the metal housing 1 is soldered to the radial metallization layer 41 and the pin 3 is completely soldered to the metallized pin hole 42 and its front and back pads. Then, the ceramic pads 5 are removed and post-soldering cleaning is performed to remove the organic components overflowing from the solder paste.

Claims

1. An integrated circuit packaging structure, comprising a metal casing (1), characterized in that, Also includes: a. The metal shell (1) has opening slots (12) on both sides of the bottom. The opening slots (12) are through slots that penetrate the bottom of the metal shell (1). Each opening slot (12) has a stepped slot (11). b. Metal insulator (2) The metal insulator (2) includes a nano-ceramic aluminum alloy substrate (21). A set of mounting through holes (22) is provided on the nano-ceramic aluminum alloy substrate (21). The outer contour edge of the nano-ceramic aluminum alloy substrate (21) is provided with stepped protrusions (23). The shape of the stepped protrusions (23) matches the shape of the stepped groove (11). The surface of the nano-ceramic aluminum alloy substrate (21) is connected with a triple structure alumina insulation layer (24). Metallization layers (25) are connected on the surface insulation layer (24) of the stepped protrusions (23) and the inner wall insulation layer (24) of the mounting through holes (22). c. A set of pins (3), each pin having a flange (31), the insulating layer (24) being connected to a pad (26) corresponding to the opening of the mounting through hole (22), each pin being sealed and welded to the metal insulator (2) through the flange, the metallization layer (25) on the inner wall of the mounting through hole (22), and the pad (26); d. The metal shell (1) and the metal insulator (2) are sealed and welded together by matching the shape of the stepped groove (11) and the stepped protrusion (23).

2. The assembly method using the integrated circuit packaging structure according to claim 1, characterized in that, Includes the following steps: S1: The PCB board (4) is provided with metallized pin holes (42) corresponding to the pins (3) on the metal housing (1). The openings of the metallized pin holes (42) on both sides of the PCB board (4) are covered with pin pads (43). On the area of ​​the PCB board (4) where the metal housing (1) is to be installed, a radial metallized layer (41) divided by gap channels is set with the center point of the area between the metallized pin holes as the origin. The gap channels include a central circular hole (41a) at the origin, a first strip gap (41b) connected to it and radiating outwards, and a second strip gap (41c) with the inner end closed and the outer end open on a part of the radial metallized layer (41). The outer end of the first strip gap (41b) is open, and the gap channels are interconnected. The second gap is set between two adjacent first gaps. The included angle between the center lines of the adjacent first gaps and the included angle between the center lines of the adjacent first gaps are both 22.5°. S2: Apply solder paste to the surface of the pin pad (43), the wall of the metallized pin hole (42), and the surface of the radial metallization layer (41). Place ceramic pads (5) on the outer edges of both ends of the radial metallization layer (41), with the positions corresponding to the inner positions of the bottom ends of the metal shell (1). The thickness of the ceramic pads (5) is smaller than the thickness of the solder paste applied to the surface of the radial metallization layer (41). When the solder paste printing thickness is d0, the solder thickness decreases to d after the organic components in the solder paste overflow into the gap channel during soldering. The area of ​​the solder paste on the surface of the radial metallization layer (41) is S0. Then the thickness of the ceramic pads is d1 = 0.85d ~ 0.9d, and the design value of the gap channel area is S = (d0 - d)S0 / d1. S3: Insert the pin (3) into the corresponding metallized pin hole (42), place the bottom ends of the metal housing (1) on the ceramic pads (5) on both sides, and make direct contact between the bottom of the metal housing (1) and the solder paste on the surface of the radial metallized layer (41); after the position of the metal housing (1) is adjusted and confirmed, reflow soldering is performed. After soldering, the ceramic pads (5) are removed and post-soldering cleaning is performed to remove the organic components overflowing from the solder paste.

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