CN-122002702-A - Board-level patch type liquid metal interconnection structure

Abstract

The invention discloses a board-level patch type liquid metal interconnection structure, and relates to the technical field of electronic packaging interconnection. The structure comprises a PDMS elastic container, a gallium-based liquid metal core material, a symmetrical one-way valve, a copper pin header, a PCB board with an indent bonding pad, a chip and a crimping packaging shell. And one end of the copper pin header is in pressure connection with the elastic accommodating body, and the other end of the copper pin header is in pressure connection with the concave bonding pad of the PCB board to form a conductive path. The invention adopts the design concept of mechanical bonding and electric interconnection decoupling, replaces the traditional rigid welding spot with liquid metal, disperses vibration stress through flexible buffering of PDMS elastomer, and solves the problem of insufficient reliability of the traditional welding spot caused by stress concentration in a vibration environment. The structure has the advantages of low contact resistance, excellent vibration resistance, compatibility with the existing SMT production line and the like, and is suitable for board-level vertical interconnection packaging scenes.

Inventors

• LI CHUNQUAN
• WANG ZIXUAN
• HUANG HONGYAN
• SHANG YULING

Assignees

• 桂林电子科技大学

Dates

Publication Date

20260508

Application Date

20260309

Claims (10)

1. 1. The plate-level patch type liquid metal interconnection structure is characterized by comprising an elastic accommodating body, a liquid metal core material, symmetrical one-way valves and a conductive connecting piece, wherein the elastic accommodating body is made of PDMS materials, a cavity for accommodating liquid metal is formed in the cavity, openings are formed in two ends of the cavity, the liquid metal core material is filled in the cavity of the elastic accommodating body and made of gallium indium alloy, the symmetrical one-way valves are respectively integrated at the openings of the two ends of the elastic accommodating body, each symmetrical one-way valve comprises a PDMS diaphragm, the diaphragm is bent and opened under the action of injection pressure to allow the liquid metal to fill in the cavity and is attached to the opening under the action of back pressure to seal the liquid metal, one end of the conductive connecting piece is in press fit with the opening of the elastic accommodating body, and the other end of the conductive connecting piece is in press fit with a bonding pad on a PCB board to form a conductive path.
2. 2. The board-level patch-type liquid metal interconnection structure of claim 1, wherein the liquid metal core material is gallium-indium alloy, the indium content is 5% -20%, the melting point is not higher than 25 ℃, the liquid metal core material is kept in a liquid state at normal temperature, and the liquid metal core material has conductivity which is not less than 3.0x 6 S/m.
3. 3. The board-level patch-type liquid metal interconnection structure of claim 1, wherein the elastic container has an outer diameter of 2-3 mm, an inner diameter of 1-2 mm and a length of 3-4 mm, the PDMS material has a Shore hardness of 40-60A, a long-term working temperature range of-40-200 ℃, and an elongation at break of not less than 300%.
4. 4. The board-level patch-type liquid metal interconnection structure of claim 1, wherein the diaphragm of the symmetrical one-way valve is bent and opened under the injection pressure of 5-15N, and the opening is sealed in a fit manner under the action of back pressure, so that zero leakage sealing of liquid metal is realized.
5. 5. The board-level patch type liquid metal interconnection structure of claim 1, wherein the crimping pressure of the copper pin header and the PCB bonding pad is 15-25N/mm < 2 >, the contact angle of a contact interface is less than 20 degrees, and the crimping resistance fluctuation is less than 0.5mΩ.
6. 6. The board-level patch type liquid metal interconnection structure of claim 1, wherein an assembly gap between the elastic accommodating body and the copper pin header is smaller than 0.05mm, and the copper pin header is made of copper with purity of more than or equal to 90%.
7. 7. The board-level patch type liquid metal interconnection structure of claim 1, wherein the bonding pad of the PCB board is of a concave structure, the concave depth is 0.1-0.3 mm, and the bonding pad and the convex cap structure of the copper pin header form complementary fit.
8. 8. The board-level patch-type liquid metal interconnection structure of claim 7, wherein the PCB board is composed of a copper-clad layer and an epoxy glass cloth substrate, the thickness of the copper-clad layer is 30-40 μm, and the epoxy glass cloth substrate is made of FR-4 material.
9. 9. The board-level patch-type liquid metal interconnect structure of claim 1, further comprising a chip electrically connected to the PCB board through the conductive connection, a plurality of the chips forming an array-type board-level system on the PCB board.
10. 10. The board-level patch-type liquid metal interconnection structure of claim 9, further comprising a crimp packaging housing fixedly connected with the PCB board through a positioning column, wherein the PCB board, the chip and the interconnection structure are integrated into an integrated packaging structure.

Description

Board-level patch type liquid metal interconnection structure Technical Field The invention relates to the technical field of electronic packaging, in particular to a patch type liquid metal interconnection structure suitable for PCB-level vertical interconnection and a packaging method thereof, which are particularly suitable for packaging scenes in a vibration environment with millimeter-level integration and high reliability requirements. Background With the rapid development of high performance computing, artificial intelligence, and 5G communication technologies, electronic devices are evolving toward high integration, millimeter level interconnection, and flexibility. Industry predicts that by 2030 the interconnect pin count for large packaged products will break through 15,000, with package sizes above 150 x 150mm, which presents a serious challenge for board level interconnect technology. The traditional board-level interconnection technology takes rigid solder (such as tin-lead alloy) and lead bonding as cores, and has the defects that firstly, the thermal expansion Coefficient (CTE) of a rigid welding spot and a PCB substrate is mismatched, stress concentration is easy to generate under random vibration load, so that the welding spot is cracked and invalid, secondly, the BGA package is easy to generate substrate warpage along with the increase of the pin number, the yield of a surface mounting process is reduced, thirdly, the parasitic inductance and the resistance of the lead bonding limit the high-frequency signal transmission capacity and cannot meet the performance requirement of a new generation electronic system, and fourthly, the traditional solder is easy to oxidize, the contact resistance is obviously increased along with the service time, and the long-term stability of the electrical performance is influenced. The unique property of the normal temperature liquid metal provides a new idea for solving the problems. Compared with the traditional materials such as metal, graphene and the like, the liquid metal has high electrical conductivity, high thermal conductivity, fluidity and self-repairing capability at normal temperature, has excellent mechanical flexibility, can buffer thermomechanical stress through deformation, and can fill a contact interface micro-gap through flow, so that the problem of rigid coupling of the traditional interconnection is fundamentally relieved. In recent years, research into liquid metal interconnect technology has advanced. For example, studies have been made to achieve multiple plug cycles stable contact for liquid metal jack technology and to verify the potential of liquid metal application in flexible circuits. However, the practical application of the liquid metal interconnection of the PCB board level still faces three major core problems that firstly, the sealing reliability is insufficient, the fluidity of the liquid metal is easy to cause leakage and cause short circuit, the existing sealing scheme is difficult to adapt to the space constraint of a millimeter-level array, secondly, a multi-physical field coupling mechanism is not clear, the fluid-solid coupling effect between the flowing of the liquid metal and the deformation of an elastic accommodating body under the vibration load is not clear, the reliability evaluation is restricted, thirdly, the large-scale assembly compatibility is poor, the design complexity is greatly increased due to the requirements of micro-size and dense arrangement, and the sealing reliability, the electrical contact stability and the array cooperativity are simultaneously considered. Therefore, it is desirable to provide a board-level chip-type liquid metal interconnection structure that can break through the above technical bottlenecks. Disclosure of Invention The invention aims to provide a board-level patch type liquid metal interconnection structure, which realizes the cooperative optimization of mechanical vibration reliability and electrical performance through the design concept of 'mechanical bonding and electrical interconnection decoupling', and solves the problems of sealing leakage, vibration failure and process compatibility in the prior art. In order to achieve the above purpose, the present invention provides the following technical solutions: A board-level patch type liquid metal interconnection structure comprises an elastic accommodating body, a liquid metal core material, a symmetrical one-way valve, a conductive connecting piece, a PCB, a chip and a crimping packaging shell. The elastic accommodating body is made of PDMS material, a cavity for accommodating liquid metal is formed in the elastic accommodating body, and openings are formed in two ends of the cavity. The outer diameter of the accommodating body is 2-3 mm, the inner diameter is 1-2 mm, and the length is 3-4 mm. The PDMS material has Shore hardness of 40A-60A, long-term working temperature range of-40 ℃ to 200 ℃, elongation at break of m