Two-photon lithography 3D printing gripping device and manufacturing method thereof, gripping array device and application

Abstract

The application provides a double-photon lithography 3D printing grabbing device and a manufacturing method thereof, a grabbing array device and application, and belongs to the chip testing technical field. The grabbing device comprises a hemispherical body, first and second conductive micro columns arranged at the lower end of the hemispherical body, and a plurality of clamping claws distributed in the circumferential direction, and a fingertip part for contacting the tin ball is formed at the end of the clamping claw. The grabbing device is sequentially provided with a thermal driving layer, an insulating isolation layer, a thermal insulation blocking layer, a conductive signal transmission layer, a stress buffer layer and an outer sheath layer from the side of the tin ball. The thermal driving layer generates micro-scale deformation during chip testing to make the fingertip part generate clamping force to clamp or release the tin ball. The first conductive micro column penetrates through the thermal driving layer, the insulating isolation layer and the thermal insulation blocking layer from the side close to the tin ball, enters the conductive signal transmission layer, and then the second conductive micro column transmits the test signal to the external test equipment. The application solves the test difficulty that the micro bump is too small to be mechanically contacted, and realizes high-density, high-speed and high-reliability signal output of the micro bump.

Description

Technical Field

[0001] This invention relates to the technical field of chip testing, and in particular to a gripping device for two-photon lithography 3D printing, its manufacturing method, gripping array device, and applications. Background Technology

[0002] The transmission rate of high-bandwidth memory (HBM) continues to improve. The HBM3 series has a single-pin rate of 6.4Gbps, while the HBM3E can reach up to 9.8Gbps; the HBM4 has a base rate of 11.7Gbps, and the SK Hynix HBM4E sample has a pin rate of 16Gbps; JEDEC's SPHBM4 standard increases the signal transmission rate to 32Gbps.

[0003] HBM's microbumps (uBump) are highly integrated, with over 7,000 on a single chip. They are extremely small: only about 28μm in diameter, with a horizontal spacing of 70μm, a vertical spacing of 110μm, a minimum spacing of 65μm, and a minimum gap of only about 37μm. Traditional mechanical linkages simply cannot be used to arrange them when receiving signals for testing.

[0004] In existing technologies, probe cards are the primary contact solution for HBM wafer-level testing. However, conventional cantilever probe cards cannot cover large-area microbump arrays, and vertical probe cards cannot meet the requirements for micro-pitch. While advanced probe cards based on microelectromechanical systems (MEMS) can match microbump arrays, the probe structure is still mainly based on rigid contact, making contact force control difficult and posing a risk of damaging the microbumps. Cavity-type test probes using shape memory metal can achieve inward retraction of the opening end to clamp the support column within a certain temperature range, but the object clamped is the support column rather than the solder ball, and the problem of heat conduction to the signal transmission layer during clamping, leading to signal layer damage, remains unresolved. Furthermore, the temperature of uBumps during HBM testing ranges from 40 to 90°C, and existing probe solutions do not utilize the material's own thermal expansion and contraction to achieve opening and closing, nor can they prevent high-temperature conduction to the signal layer.

[0005] In view of this, a novel gripping device for two-photon lithography 3D printing, its manufacturing method, gripping array device, and its application are proposed to solve all or part of the above problems. Summary of the Invention

[0006] To address at least one of the aforementioned problems and deficiencies in the prior art, embodiments of the present invention provide a gripping device and its manufacturing method, a gripping array device, and its application using two-photon lithography 3D printing. A hemispherical gripping array is manufactured using two-photon lithography 3D printing. The 30μm fingertip can be inserted into a 37μm microbump gap. A six-layer functional structure works synergistically to achieve deformation gripping of the thermally driven layer, heat insulation layer to block heat transmission, and 50Ω microstrip line transmission of test signals in the conductive signal transmission layer. Conductive micropillars penetrate to separate the thermally driven and signal transmission circuits, solving the test contact problem of excessively small HBM microbump size and the inability to arrange mechanical linkages. This achieves the manufacturing of complex three-dimensional grippers at the micrometer level and high-density, high-speed, and high-reliability signal transmission. The technical solution is as follows:

[0007] According to one aspect of the present invention, a gripping device for two-photon lithography 3D printing is provided, comprising N×M hemispherical grippers, each gripper corresponding to contacting solder balls on N×M microbumps of the chip under test.

[0008] Each gripper includes a hemispherical body, a first conductive micropillar and a second conductive micropillar disposed at the lower end of the hemispherical body, and multiple grippers distributed along the circumference of the gripper, with the ends of each gripper forming fingertips for contacting solder balls.

[0009] Each gripper has a multi-layered functional structure arranged sequentially from the side that contacts the solder ball outwards. The multi-layered functional structure includes a thermal drive layer, an insulating isolation layer, a thermal insulation blocking layer, a conductive signal transmission layer, a stress buffer layer, and an outer sheath layer.

[0010] The thermal drive layer is disposed on the side near the solder ball in the form of a mesh microstrip line structure, with mesh holes through which the first conductive micropillars pass. The mesh microstrip line structure is configured to be electrically connected to the flexible electrothermal film for heating and / or temperature sensing. The thermal drive layer is configured to generate microscale deformation within the chip test temperature range to generate a clamping force at the fingertip to clamp or release the solder ball.

[0011] The insulating isolation layer is configured to prevent short circuits in the conductive path between the thermally driven layer and the conductive signal transmission layer;

[0012] The thermal insulation barrier layer is configured to block the heat generated by the solder balls from being conducted to the conductive signal transmission layer;

[0013] The conductive signal transmission layer includes a signal transmission line structure configured to transmit test signals from the microbumps;

[0014] The stress buffer layer is configured to absorb mechanical stress and provide an elastic modulus transition.

[0015] The self-heating driven layer of the first conductive micropillar penetrates the thermal drive layer, the insulating isolation layer, and the heat insulation blocking layer on the side near the solder ball and enters the conductive signal transmission layer. The top of the first conductive micropillar is in direct contact with the solder ball, and the bottom of the first conductive micropillar is electrically connected to the signal transmission line structure.

[0016] The second conductive micropillar is electrically connected to the signal transmission line structure of the conductive signal transmission layer and is configured to transmit the test signal received by the signal transmission line structure to an external test device.

[0017] According to another aspect of the present invention, a method for manufacturing a gripping device for two-photon lithography 3D printing is provided, the method being used to manufacture the gripping device described in the above aspect. The manufacturing method includes:

[0018] Preparation of hydrogel substrates;

[0019] The hydrogel substrate is patterned using femtosecond optical sheet patterning technology to form a three-dimensional pattern corresponding to the hemispherical gripper shape.

[0020] The patterned hydrogel substrate is pre-shrinked, with a shrinkage ratio of 10 to 15 times.

[0021] Region-selective material deposition is performed, sequentially depositing the thermally driven layer, insulating isolation layer, thermal insulation blocking layer, conductive signal transmission layer, stress buffer layer, outer sheath layer, and the materials of the first conductive micropillar and the second conductive micropillar;

[0022] The deposited structure is then cleaned and dried.

[0023] Imaging observation was performed to obtain the gripping device.

[0024] According to another aspect of the present invention, a gripper array device for two-photon lithography 3D printing is provided. The gripper array device includes:

[0025] substrate; and

[0026] A gripping device as described above is disposed on a substrate;

[0027] N×M hemispherical gripper arrays are arranged, and the spacing between the second conductive micropillars of each gripper matches the staggered arrangement spacing of the HBM microbump array. The horizontal spacing of the HBM microbump array is 70μm and the vertical spacing is 110μm.

[0028] The second conductive micropillar is set to correspond to the signal lead-out line on the substrate.

[0029] The flexible electrothermal film is electrically connected to the mesh microstrip structure of the thermally driven layer and is insulated from the conductive signal transmission layer.

[0030] According to another aspect of the present invention, an application of a two-photon lithography 3D printed gripper is provided in HBM high-bandwidth memory testing, the gripper being a gripper manufactured according to the gripper described above or a gripper manufactured according to the manufacturing method described above.

[0031] In some embodiments, the fingertips of N×M hemispherical grippers respectively contact the solder balls of N×M microbumps of the HBM chip under test. The first conductive micropillar transmits the test signal of the microbump to the second conductive micropillar via a signal transmission line structure, and then transmits it to the external test equipment. At the same time, the thermal drive layer controls the clamping or releasing of the grippers according to the temperature change.

[0032] The gripping device and its manufacturing method, gripping array device, and applications for two-photon lithography 3D printing provided by the embodiments of the present invention have at least one or a portion of the following advantages:

[0033] (1) The grippers of the gripping device of the present invention correspond to N×M micro bumps that contact the chip under test. Each hemispherical gripper includes a hemispherical body, a first conductive micropillar, a second conductive micropillar and multiple claws. The fingertips of the claws are used to contact the solder ball. A thermal driving layer, an insulating isolation layer, a heat insulation blocking layer, a conductive signal transmission layer, a stress buffer layer and an outer sheath layer are arranged sequentially from the solder ball outward. The first conductive micropillar penetrates from the side of the thermal driving layer near the solder ball to the conductive signal transmission layer. The second conductive micropillar is led out from the conductive signal transmission layer. The mesh microstrip structure of the thermal driving layer is only connected to the flexible electrothermal film and is insulated from the conductive signal transmission layer, so as to realize the separation of thermal driving and signal transmission circuit, while ensuring gripping reliability and high-speed signal integrity.

[0034] (2) The fingertip width is preferably 30μm, which is less than the minimum gap between the micro-bumps of 37μm, so that the gripper can be inserted between the micro-bumps and contact the solder ball, breaking through the bottleneck that traditional mechanical linkages cannot be arranged; the fingertip height is preferably 80μm, covering the height of the micro-bumps by 35μm and leaving a margin; the total thickness of the multi-layer functional structure is preferably 53μm, covering the height of the micro-bumps by 35μm and having a structural margin of 18μm to ensure reliable clamping;

[0035] (3) The thickness of the thermal drive layer is preferably 8μm. The liquid crystal elastomer nanofibers are oriented and arranged by an electric field, and generate 2~5μm of directional contraction in the temperature range of 40~90℃, so that the fingertip generates a clamping force of 0.1~0.3N, realizing the opening and closing by the thermal expansion and contraction of the material itself without the need for external mechanical drive; the in-plane conductive network is constructed by silver-plated graphene sheets, and the first conductive micropillar passes through the mesh of the mesh microstrip line structure and directly contacts the solder ball, ensuring that the circuit of thermal drive and signal transmission does not contact each other;

[0036] (4) The thickness of the insulating isolation layer is preferably 5μm, the breakdown strength is greater than 300kV / mm, and the withstand voltage is greater than 1.5kV to prevent short circuit between the thermal drive layer and the conductive signal transmission layer; in particular, to prevent short circuit between the mesh microstrip structure of the thermal drive layer or the heating drive signal and the conductive signal transmission layer that transmits the solder ball test signal; the hollow silica nanospheres reduce the dielectric constant to 2.0 and reduce the parasitic capacitance of the signal; the aperture of the photolithographic opening is preferably 8μm, and the space between the micropillar and the hole wall is filled with insulating glue for sealing;

[0037] (5) The thickness of the thermal insulation barrier layer is preferably 8 μm, which is composed of 100 cycles of alternating stacked atomic layer deposited alumina thin film and silica aerogel, with an equivalent thermal conductivity of 0.005 W / (m·K) and a thermal resistance of 1.6 K·m. 2 / W, blocks the heat from the microbumps from being transmitted to the conductive signal transmission layer, preventing high temperature from damaging the signal layer;

[0038] (6) The thickness of the conductive signal transmission layer is preferably 15 μm, and the characteristic impedance of the signal transmission line structure is 50Ω±2Ω, supporting a signal transmission rate of more than 32Gbps; the negative expansion nanopowder of zirconium tungstate reduces the coefficient of thermal expansion to less than 30ppm / ℃, ensuring impedance stability when the temperature fluctuates.

[0039] (7) The thickness of the stress buffer layer is preferably 12 μm and the elastic modulus is 50 MPa, which is between about 2 GPa of the conductive signal transmission layer and about 3 GPa of the outer sheath layer. It can be compressed and deformed by 2 μm during thermal cycling or mechanical vibration, eliminating interface stress concentration and protecting the rigid layer from cracking.

[0040] (8) The outer sheath layer is preferably 5μm thick, and the nickel-plated carbon fiber forms a three-dimensional network, which has a shielding effectiveness of 40dB against 20GHz electromagnetic waves, providing electromagnetic shielding and mechanical protection to prevent the internal structure from being mechanically damaged or chemically corroded.

[0041] (9) The first and second conductive micropillars are composed of silver-plated copper nanowires and polyimide precursor binder. The diameter is preferably 10 μm, the column spacing matches the staggered arrangement spacing of the HBM microbump array, the total height is greater than 36 μm, the single column resistance is 0.5 mΩ, and the bulk resistivity is 3 × 10⁻⁶. -5 Ω·cm, ensuring high conductivity of the vertical signal channel and matching with the HBM micro-bump array;

[0042] (10) Using two-photon lithography, through hydrogel preparation, femtosecond light sheet patterning, pre-shrinking, regional selective material deposition, cleaning and drying and imaging observation, the manufacturing of micro-nano-level 3D complex material grippers can be realized. The pre-shrinking ratio can reach 13 times, breaking through the limitation of traditional processing technology that cannot manufacture micron-level complex material parts.

[0043] (11) Region-selective material deposition includes size-selective assembly. By adjusting the intensity of the femtosecond laser, the density of the hydrogel structure is controlled, and different component materials are deposited in different regions to form multi-layer functional structures, especially the mesh microstrip structure that forms the thermally driven layer, so as to realize the integrated manufacturing of multiple materials.

[0044] (12) The gripper array device includes a substrate and N×M grippers, with a second conductive micropillar array arranged and the pillar spacing matching the staggered arrangement spacing of the HBM microbump array, supporting large-scale parallel testing and meeting the high-density, high-parallel testing requirements of HBM.

[0045] (13) There are 8192 grippers, divided into four areas, with 2048 grippers in each area; the outer wall is attached with a flexible electric heating film that has both heating and self-temperature sensing functions, with a resistance of 10~50Ω, so that each gripper can have independent temperature feedback; the flexible electric heating film is electrically connected to the mesh microstrip structure of the heat-driven layer and is insulated from the conductive signal transmission layer.

[0046] (14) One end of the flexible electrothermal film is connected to the mesh microstrip structure of the thermal drive layer, and the other end is connected to the heating control circuit on the substrate; the signal lead-out line on the substrate is electrically connected to the signal transmission line structure of the second conductive micropillar or the conductive signal transmission layer, and transmits the test signal received by the signal transmission line structure to the external test equipment; the flexible electrothermal film is insulated from the conductive signal transmission layer to avoid short circuit; a thermoelectric cooler is set under the substrate to keep the substrate temperature constant at 15°C, providing a cold plate basis for the differential heating of the gripper;

[0047] (15) In the HBM test, the fingertips of N×M hemispherical grippers contact the solder balls of N×M microbumps respectively. The first conductive micropillar transmits the test signal of the microbumps to the second conductive micropillar through the signal transmission line structure, and then transmits it to the external test equipment. At the same time, the thermal drive layer controls the clamping or releasing of the grippers according to the temperature change. The mesh microstrip structure of the thermal drive layer is only connected to the flexible electrothermal film and not connected to the conductive signal transmission layer, so as to realize the high density, high speed and high reliability transmission of the microbump signal without damaging the signal layer. Attached Figure Description

[0048] These and / or other aspects and advantages of the present invention will become apparent and readily understood from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which:

[0049] Figure 1 This is a schematic diagram of the overall structure of a gripper in a gripping device according to an embodiment of the present invention;

[0050] Figure 2 This is a schematic diagram of the cross-sectional structure of a gripping device according to an embodiment of the present invention;

[0051] Figure 3 This is a schematic diagram of the manufacturing process of a gripping device for two-photon lithography 3D printing according to an embodiment of the present invention.

[0052] Figure 4 This is a schematic diagram of the process flow for two-photon lithography 3D printing according to an embodiment of the present invention;

[0053] Figure 5 This is a schematic diagram of the overall architecture of a gripper temperature control system according to an embodiment of the present invention. Detailed Implementation

[0054] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. In this specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as a limitation thereof.

[0055] This invention provides a gripper device for two-photon lithography 3D printing, primarily used for testing High Bandwidth Memory (HBM) chips. The HBM chip under test is placed horizontally on a worktable with its uBump faces downwards, forming an N×M matrix. A single HBM chip under test typically has over 7000 uBumps. Each uBump generally includes a copper pillar and a solder ball (soldercap) at the top of the pillar. Hemispherical grippers, manufactured using two-photon lithography 3D printing, contact each corresponding solder ball in the N×M matrix array. The temperature of each gripper can be independently and precisely controlled to achieve gripper closure.

[0056] See Figure 1 The diagram shows the overall structure of a gripper 110 in a gripper device according to one embodiment.

[0057] See Figure 2 The diagram shows a schematic diagram of the design principle of the functional layer cross-section of a gripping device according to an embodiment.

[0058] Combination Figure 1 and Figure 2 As shown, each hemispherical gripper 110 includes a hemispherical body 111, a second conductive micropillar 112 disposed at the lower end of the hemispherical body 111, and a plurality of grippers 113 distributed circumferentially along the gripper 110; wherein, the end of each gripper 113 forms a fingertip 114 for contacting the solder ball. Each hemispherical gripper 110 also includes a first conductive micropillar 115, which protrudes from the thermally driven layer on the side near the solder ball and directly contacts the solder ball.

[0059] like Figure 2As shown, the thermally driven layer forms a mesh-like microstrip line structure. The first conductive micropillar 115 passes through the mesh of the microstrip line structure; the second conductive micropillar 112 extends downward from the conductive signal transmission layer to transmit the test signal to the external test equipment. The mesh-like microstrip line structure of the thermally driven layer is only electrically connected to the external flexible electrothermal film and is not connected to the conductive signal transmission layer to avoid short circuits.

[0060] Each hemispherical gripper 110 has a multi-layered functional structure arranged sequentially from the side of the contact micro-protrusion outwards. The multi-layered functional structure includes six layers in sequence: a thermal drive layer, an insulating isolation layer, a thermal insulation blocking layer, a conductive signal transmission layer, a stress buffer layer, and an outer sheath layer.

[0061] Specifically, the thermally driven layer is disposed on the side closest to the solder ball and configured to generate microscale deformation within the HBM test temperature range, so that the fingertip 114 generates a clamping force to clamp or release the solder ball. The thermally driven layer has a mesh microstrip structure with mesh openings through which the first conductive micropillar 115 passes. This mesh microstrip structure is used for electrical connection with the flexible electrothermal film to achieve heating and / or self-sensing temperature. The mesh microstrip structure is insulated from the conductive signal transmission layer. An insulating layer is disposed between the thermally driven layer and the conductive signal transmission layer, configured to prevent short circuits in the conductive path between the thermally driven layer and the conductive signal transmission layer; in particular, it prevents short circuits between the mesh microstrip structure of the thermally driven layer or the heating drive signal and the conductive signal transmission layer that transmits the solder ball test signal. A heat-insulating barrier layer is disposed between the insulating isolation layer and the conductive signal transmission layer, configured to block the heat generated by the micro-bumps from being conducted to the conductive signal transmission layer; a signal transmission line structure is embedded inside the conductive signal transmission layer, configured to transmit the test signal from the micro-bumps; a stress buffer layer is disposed between the conductive signal transmission layer and the outer sheath layer, configured to absorb mechanical stress and provide an elastic modulus transition; the outer sheath layer is disposed on the outermost side, configured to provide electromagnetic shielding and mechanical protection.

[0062] Furthermore, the signal transmission line structure embedded within the conductive signal transmission layer is a structure wrapped in an insulating dielectric material, which has a gap space through which the second conductive micropillar 112 passes. The first conductive micropillar 115 enters the conductive signal transmission layer from the side of the thermally driven layer near the solder ball, sequentially penetrating the thermally driven layer, the insulating isolation layer, and the thermally insulating blocking layer. The first conductive micropillar 115 passes through the mesh of the microstrip line structure and the gap space of the signal transmission line structure, and is wrapped and fixed by the insulating dielectric material. The top end of the first conductive micropillar 115 directly contacts the solder ball, and the bottom end of the first conductive micropillar 115 is electrically connected to the signal line of the signal transmission line structure, and is insulated from the ground layer of the signal transmission line structure by the insulating dielectric material. The second conductive micropillar 112 is electrically connected to the signal transmission line structure of the conductive signal transmission layer and is configured to transmit the test signal received by the signal transmission line structure to an external test device.

[0063] It should be noted that the first conductive micropillar 115 serves only as a vertical signal channel from the solder ball to the conductive signal transmission layer. Its top end is in direct contact with the solder ball, and its bottom end is only electrically connected to the top layer signal line of the signal transmission line structure. When the first conductive micropillar 115 passes through the gap space of the signal transmission line structure, its outer periphery is wrapped with insulating dielectric material, which insulates it from the intermediate dielectric layer and the bottom ground layer. The second conductive micropillar 112 serves as a vertical signal channel from the conductive signal transmission layer to the external test equipment and is electrically connected to the top layer signal line. The mesh microstrip structure of the thermal drive layer is only used to connect the flexible electrothermal film for heating and / or temperature sensing, and it is not connected to the conductive signal transmission layer. Therefore, there will be no short circuit caused by one end of the first conductive micropillar 115 being connected to the solder ball and then directly connected to the ground layer or the entire signal transmission line structure through the second conductive micropillar 112, nor will the heating drive signal of the thermal drive layer be short-circuited with the solder ball test signal.

[0064] In HBM testing, the fingertips 114 of N×M hemispherical grippers 110 respectively contact the solder balls of N×M microbumps of the HBM chip under test. The first conductive micropillar 115 transmits the test signal of the microbump to the second conductive micropillar 112 through the signal transmission line structure, and then the second conductive micropillar 112 transmits it to the external test equipment. At the same time, the thermal drive layer controls the clamping or releasing of the grippers 110 according to the temperature change.

[0065] In one specific embodiment, the width of the fingertip 114 is 25-35 μm, preferably 30 μm, which is smaller than the minimum gap between the micro-bumps (approximately 37 μm); the height of the fingertip 114 is 75-85 μm, preferably 80 μm, covering the height of the micro-bumps (approximately 35 μm) with a margin. The total thickness of the multilayer functional structure is 50-55 μm, preferably 53 μm, covering the height of the micro-bumps with a structural margin of approximately 15-20 μm.

[0066] In a preferred embodiment, the fingertip 114, with a width of 30 μm, can be inserted between microbumps with a minimum gap of 37 μm, and the total thickness of 53 μm can cover the microbump height of 35 μm with a structural margin of 18 μm. Thermal actuation occurs at the very tip of the fingertip 114 of the gripper 110, i.e., near the microbumps, but the heat is confined to an extremely thin local area and will not be conducted outward to the conductive signal transmission layer.

[0067] In one specific embodiment, the thickness of the thermally driven layer is 5-10 μm, preferably 8 μm. Preferably, by mass percentage, the thermally driven layer consists of 50% liquid crystal elastomer nanofibers, 30% silver-plated graphene sheets, 15% liquid metal microdroplets, and 5% silane coupling agent.

[0068] More preferably, the liquid metal microdroplets are gallium-indium-tin (Ga-In-Sn) alloys with a particle size of 2~5μm; the liquid crystal elastomer nanofibers are oriented and aligned by an electric field, generating a directional contraction of 2~5μm within a temperature range of 40~90℃, causing the fingertip 114 to generate a clamping force of 0.1~0.3N; the silver-plated graphene sheet is used to construct an in-plane conductive network, which forms a mesh microstrip structure of the thermally driven layer; the first conductive micropillar 115 passes through the mesh of the mesh microstrip structure and directly contacts the tin ball; the mesh microstrip structure is used to electrically connect with the flexible electrothermal film to heat the thermally driven layer and / or self-sensing temperature, and the mesh microstrip structure is insulated and isolated from the conductive signal transmission layer and is not connected to the conductive signal transmission layer.

[0069] In one specific embodiment, the range (coverage area) of the thermal drive layer is set to only the part of the fingertip 114 that directly contacts the solder ball of the micro-bump. After being heated, the thermal drive layer produces micro-scale deformation, realizing the clamping or releasing of the gripper 110. The first conductive micro-pillar 115 independently passes through the mesh of the thermal drive layer to transmit the solder ball signal to the signal transmission line structure of the conductive signal transmission layer. It is isolated from the heating drive circuit of the thermal drive layer to prevent the thermal drive layer from short-circuiting with the conductive signal transmission layer.

[0070] In a preferred embodiment, liquid crystal elastomer nanofibers, oriented by an electric field and only 8 μm thick, exhibit a directional shrinkage of approximately 3 μm within a temperature range of 40–90 °C. This micro-deformation is sufficient to generate a clamping force of approximately 0.1–0.3 N at the fingertip 114 of the gripper 110. A silver-plated graphene sheet constructs an in-plane conductive network that does not cover the fingertip 114, and has a bulk resistivity of approximately 5 × 10⁻⁶. -4 Ω·cm. The first conductive micropillar 115 passes through the mesh of the mesh microstrip structure of the thermally driven layer and directly contacts the solder balls of the microbumps, ensuring that the circuits for thermal driving and signal transmission do not come into contact; the flexible electrothermal film is connected to the mesh microstrip structure and is not connected to the conductive signal transmission layer.

[0071] In one specific embodiment, the thickness of the insulating layer is 3-8 μm, preferably 5 μm. Preferably, by mass percentage, the insulating layer consists of 80% fluorinated polyimide, 15% hollow silica nanospheres, and 5% silane coupling agent. The hollow silica nanospheres have a particle size of 15-25 nm, preferably 20 nm; the insulating layer has a breakdown strength greater than or equal to 300 kV / mm and a withstand voltage greater than or equal to 1.5 kV; the insulating layer has a photolithographically etched opening at the penetration point of the first conductive micropillar 115, the opening having a diameter of 5-10 μm, preferably 8 μm, and the space between the first conductive micropillar 115 and the wall of the photolithographically etched opening is filled with insulating adhesive.

[0072] In a preferred embodiment, the insulating layer isolates the conductive path between the thermally driven layer and the conductive signal transmission layer, preventing short circuits and providing thermal insulation. Specifically, the insulating layer prevents a short circuit between the mesh microstrip structure of the thermally driven layer or the heating drive signal and the conductive signal transmission layer transmitting the solder ball test signal. Fluorinated polyimide is formed into a 5μm thin film by spin coating or chemical vapor deposition, exhibiting a breakdown strength greater than 300kV / mm, and the 5μm thickness can withstand a voltage greater than 1.5kV. Hollow silica nanospheres reduce the dielectric constant to 2.0, decreasing parasitic capacitance. The layer is etched with an 8μm aperture at the penetration point of the first conductive micropillar 115, and the space between the micropillar and the aperture wall is sealed with insulating adhesive.

[0073] In one specific embodiment, the thickness of the heat-insulating barrier layer is 5-10 μm, preferably 8 μm. Preferably, the heat-insulating barrier layer is composed of 100 alternating stacks of atomic layer deposited alumina thin films and silica aerogel, with a total thickness of 550-650 nm, preferably 600 nm, and the remaining thickness is filled with polyimide aerogel; the equivalent thermal conductivity of the heat-insulating barrier layer is 0.005 W / (m·K), and the thermal resistance is 1.6 K·m. 2 / W.

[0074] Furthermore, the thermal insulation layer is used for core insulation, preventing heat transfer from the microbumps to the conductive signal transmission layer. Atomic Layer Deposition (ALD) technology can precisely control the 6nm multilayer nanostructure per cycle. The alumina film reflects infrared thermal radiation, while the silica aerogel nanolayer blocks heat conduction, achieving an equivalent thermal conductivity of approximately 0.005 W / (m·K) over 100 cycles. The thermal resistance of an 8μm thickness is approximately 1.6 K·m. 2 / W.

[0075] In a preferred embodiment, the first conductive micropillar 115 penetrating the thermal insulation barrier layer has a diameter of 10 μm and a cross-sectional area of ​​78.5 μm. 2 The thermal resistance of a single column is approximately 200 K / W, and the total heat flux of 2048 columns is less than 0.5 W, resulting in an impact of less than 3% on thermal insulation.

[0076] In one specific embodiment, the thickness of the conductive signal transmission layer is 10-20 μm, preferably 15 μm. Preferably, by mass percentage, the conductive signal transmission layer consists of 35% fluorinated liquid crystal elastomer, 15% zirconium tungstate negative expansion nanoparticles, 30% silver-plated hollow glass microspheres, 10% silver-plated carbon nanotubes, 5% hollow silica nanospheres, and 5% crosslinking agent. The signal transmission line structure includes a top signal line, an intermediate dielectric layer, and a bottom ground layer. The top signal line is a silver-plated polyimide nanofiber signal line with a line width of 5~10μm, preferably 8μm, and a thickness of 1~5μm, preferably 2μm; the thickness of the middle dielectric layer is 5~15μm, preferably 10μm, and the dielectric constant is 2.0; the bottom ground layer is a silver-plated graphene ground layer with a thickness of 2~5μm, preferably 3μm; the characteristic impedance of the signal transmission line structure is 50Ω±2Ω, supporting a signal transmission rate of greater than or equal to 32Gbps; the negative expansion nanoparticles of zirconium tungstate reduce the thermal expansion coefficient of the conductive signal transmission layer to less than or equal to 30ppm / ℃.

[0077] In a preferred embodiment, a conductive signal transmission layer is used to embed a signal transmission line structure to achieve high-speed signal transmission with 50Ω impedance control. This layer incorporates a three-layer structure using two-photon polymerization technology. The top layer is a silver-plated polyimide nanofiber signal line with a line width of 8μm, a spacing of 15μm, and a thickness of 2μm; the middle layer is a low-loss dielectric layer with a thickness of 10μm and a dielectric constant of 2.0; and the bottom layer is a silver-plated graphene ground layer with a thickness of 3μm. A first conductive micropillar 115 penetrates sequentially from the side of the thermally driven layer near the solder ball, passing through the thermally driven layer, the insulating isolation layer, and the thermally insulating blocking layer, and enters the layer. It passes through the gaps in the signal transmission line structure and is secured by the insulating dielectric material. Its bottom end connects to the top layer signal line and is insulated from the middle dielectric layer and the bottom ground layer. A second conductive micropillar 112 connects to the top layer signal line and extends outwards to transmit the test signal to external testing equipment. Zirconium tungstate negative expansion filler reduces the coefficient of thermal expansion to less than 30ppm / / ℃, ensuring impedance stability during temperature fluctuations. The characteristic impedance of the entire signal transmission line structure is 50Ω±2Ω, supporting signal rates greater than 32Gbps.

[0078] In one specific embodiment, the thickness of the stress buffer layer is 10-15 μm, preferably 12 μm. Preferably, by mass percentage, the stress buffer layer consists of 70% thermoplastic polyurethane elastomer nanofilm, 25% silica aerogel micropowder, and 5% crosslinking agent; the elastic modulus of the stress buffer layer is 45-55 MPa, between approximately 2 GPa of the conductive signal transmission layer and approximately 3 GPa of the outer sheath layer, and is configured to compress and deform by 1-5 μm (typically precisely controlled within 2-3 μm) during thermal cycling or mechanical vibration.

[0079] In a preferred embodiment, a stress-buffered layer is used to absorb microscale mechanical stress and provide a modulus transition. This layer is formed as a 12 μm film by inkjet printing, with an elastic modulus of approximately 50 MPa, falling between approximately 2 GPa of the conductive signal transmission layer and approximately 3 GPa of the outer sheath layer, thus eliminating interfacial stress concentration. Aerogel micropowder reduces the thermal conductivity to 0.05 W / (m·K), aiding in thermal insulation. Under thermal cycling or mechanical vibration, this layer can compress and deform by approximately 2 μm, protecting the overlying rigid layer from cracking. The thermoplastic polyurethane elastomer nanofilm can be Shore A80.

[0080] In one specific embodiment, the thickness of the outer sheath layer is 3~8μm, preferably 5μm. Preferably, by mass percentage, the outer sheath layer consists of 60% polyetheretherketone nanocoating, 30% nickel-plated carbon fiber, and 10% manganese-zinc ferrite nanosheets; the nickel-plated carbon fiber forms a three-dimensional network within the outer sheath layer, providing a shielding effectiveness of 35~50dB against 20GHz electromagnetic waves.

[0081] In a preferred embodiment, the outer sheath layer serves for electromagnetic shielding and mechanical protection. A dense 5μm coating is formed using plasma-enhanced chemical vapor deposition (PECVD). Nickel-plated carbon fibers form a three-dimensional network within the 5μm thickness, providing approximately 40dB of shielding effectiveness against 20GHz electromagnetic waves. Manganese-zinc ferrite nanosheets absorb residual radiation. This layer serves as the outermost layer of the gripper 110, preventing mechanical damage or chemical corrosion to the internal structure. The nickel-plated carbon fibers can be 1–2μm in length.

[0082] In one specific embodiment, both the first conductive micropillar 115 and the second conductive micropillar 112 are composed of silver-plated copper nanowires and a polyimide precursor binder; wherein, the diameter of the silver-plated copper nanowires is 90~110nm, preferably 100nm, and the length is 30~40μm, preferably 36μm, and they are oriented vertically. The diameter of the first conductive micropillar 115 and the second conductive micropillar 112 ranges from 8~12μm, and the spacing between the pillars matches the staggered arrangement spacing of the HBM microbump array (for example, the horizontal spacing of the HBM microbump array is 70μm, and the vertical spacing is 110μm); the total height of the first conductive micropillar 115 and the second conductive micropillar 112 is greater than or equal to 36μm, the single pillar resistance is 0.5mΩ, and the bulk resistivity is 3×10⁻⁶. -5 Ω·cm.

[0083] In a preferred embodiment, the first conductive micropillar 115 extends from the side of the thermally driven layer near the solder ball, sequentially passing through the thermally driven layer, the insulating isolation layer, and the thermally insulating blocking layer, and enters the conductive signal transmission layer. The total height, combined with the second conductive micropillar 112, is greater than 36 μm. The material is silver-plated copper nanowires arranged in a directional pattern, and the polymer binder is filled with a polyimide precursor. Preferably, the diameter of the second conductive micropillar 112 is 10 μm, and the spacing between the pillars matches the spacing of the microbumps, for example, 70 μm × 110 μm staggered arrangement in HBM; the number is approximately 2048 micropillars per region of HBM, totaling approximately 8192 micropillars across four regions; these second conductive micropillars 112 arrays function as vertical signal channels. The copper nanowires are oriented vertically, forming a highly conductive pathway with a bulk resistivity of approximately 3 × 10⁻⁶. -5 The resistance of a single column is approximately 0.5 mΩ·cm, much smaller than the contact resistance. The polymer binder, after curing, ensures a sealed interface between the micropillar and the surrounding insulating layer. The top of the first conductive micropillar 115 is exposed in the thermally driven layer, directly contacting the solder ball; the bottom of the second conductive micropillar 112 passes through the gap in the signal transmission line structure and is electrically connected to the top layer signal line of the conductive signal transmission layer, while being insulated from the intermediate dielectric layer and the bottom ground layer, finally extending outward from the conductive signal transmission layer to the external test equipment.

[0084] Based on the structure of the gripping device described above in this invention, this invention also provides a method for manufacturing the gripping device for two-photon lithography 3D printing.

[0085] See Figure 3 The document illustrates a process flow for manufacturing a gripper device using two-photon lithography 3D printing according to one embodiment. The manufacturing method includes the following steps:

[0086] Step S210: Prepare a hydrogel substrate;

[0087] Step S220: The hydrogel substrate is patterned using femtosecond optical sheet patterning technology to form a three-dimensional pattern corresponding to the shape of the hemispherical gripper 110.

[0088] Step S230: Perform a pre-shrinkage treatment on the patterned hydrogel substrate, with a shrinkage ratio of 11 to 15 times;

[0089] Step S240: Perform region-selective material deposition, sequentially depositing the thermally driven layer, insulating isolation layer, thermal insulation blocking layer, conductive signal transmission layer, stress buffer layer, outer sheath layer, and the materials of the first conductive micropillar 115 and the second conductive micropillar 112;

[0090] Step S250: Clean and dry the deposited structure;

[0091] Step S260: Perform imaging observation to obtain the gripper device printed by two-photon lithography 3D printing.

[0092] In step S240, the region-selective material deposition includes size-selective assembly, which controls the density of the hydrogel structure by adjusting the intensity of the femtosecond laser, and deposits different component materials in different regions to form a multilayer functional structure, especially the mesh microstrip structure of the thermally driven layer.

[0093] See Figure 4 The diagram illustrates the process flow of two-photon lithography 3D printing in one embodiment.

[0094] like Figure 4 As shown, the main process flow of two-photon lithography 3D printing is as follows: hydrogel preparation --> femtosecond photosheet patterning modification --> pre-shrinking --> material deposition --> cleaning and drying --> imaging observation.

[0095] Furthermore, Figure 4 Exemplary examples (simulation diagrams) of each process are shown: A is the femtosecond light sheet patterning process, B is a schematic diagram of the photolysis process, C is the 13x pre-shrinking process, and D is the region-selective deposition and size-selective assembly process. Figure 4 The right side also shows example diagrams of printed wood stack structures and spiral / mesh structures.

[0096] Taking the gripper 110 used for HBM testing as an example, it is a micron-level 3D part with a complex material composition, which cannot be manufactured by traditional processing. Therefore, it is printed using an ultra-high-speed three-dimensional two-photon lithography system. This process can be used to support the manufacturing of the micro-nano-level 3D complex material gripper 110.

[0097] Furthermore, this embodiment of the invention also provides a gripper array device, which includes a substrate and N×M hemispherical grippers 110 disposed on the substrate; the N×M hemispherical grippers 110, 3D printed by two-photon lithography, are arranged in an array, and the spacing of the second conductive micropillars 112 of each gripper 110 matches the staggered arrangement spacing of the HBM microbump array (for example, the horizontal spacing of the HBM microbump array is 70μm and the vertical spacing is 110μm). The second conductive micropillars 112 are correspondingly connected to the signal lead-out lines on the substrate; the flexible electrothermal film is electrically connected to the mesh microstrip structure of the thermally driven layer and is insulated from the conductive signal transmission layer.

[0098] In a preferred embodiment, there are 8192 N×M hemispherical grippers 110, divided into four regions with 2048 grippers in each region. Each gripper 110 has a flexible electrothermal film attached to its outer wall. This flexible electrothermal film has both heating and self-temperature sensing functions and is a purely resistive load with a resistance of 10~50Ω. The flexible electrothermal film is electrically connected to the mesh microstrip structure of the thermal drive layer, and is insulated from the conductive signal transmission layer by an insulating layer. The flexible electrothermal film is not connected to the conductive signal transmission layer to prevent a short circuit between the heating drive signal and the solder ball test signal.

[0099] Furthermore, one end of the flexible electrothermal film is connected to the mesh microstrip structure of the thermally driven layer, and the other end is connected to the heating control circuitry on the substrate. The signal output circuitry on the substrate is electrically connected to the signal transmission line structure of the second conductive micropillar 112 or the conductive signal transmission layer. The signal output circuitry is configured to transmit the test signal received by the signal transmission line structure to an external test device. The flexible electrothermal film is insulated from the conductive signal transmission layer. A thermoelectric cooler (TEC) is also disposed below the substrate. The cold side of the thermoelectric cooler is attached to the bottom surface of the substrate, and the hot side is attached to the heat sink. The thermoelectric cooler is configured to maintain the temperature of the substrate at 12~18℃ (preferably 15℃).

[0100] In one specific embodiment, each gripper 110 in the gripper device or gripper array device is precisely temperature-controlled by the following temperature control method:

[0101] The gripper 110 is a precision device. To minimize its size, an electrothermal film with both heating and temperature measurement functions is selected. Its advantages are: 1) Space saving: no separate temperature sensor is required; 2) Zero heat conduction delay: the temperature of the heating point itself is measured, with no heat conduction hysteresis; 3) Independent temperature measurement of gripper 110: each gripper 110 in the N×M gripper array independently obtains temperature feedback.

[0102] The working principle or control process of the temperature control method is as follows: Heating stage (PWM ON): A large current (hundreds of mA to several A) flows through the heating film, generating a thermal effect to heat the gripper 110. Temperature measurement stage (PWM OFF): A small constant current I of 1 mA is injected into the heating film. sense Measure the voltage V across the heating film. meas The current resistance value is obtained as: R = V meas / I senseThe electrothermal film has a defined temperature coefficient of resistance (TCR, α≈0.003~0.006 / ℃). Within the operating temperature range of 40~90℃, R and T are approximately linear: T=T0+(R-R0) / (R0·α). Where T0 is the reference temperature, recorded during calibration, such as 20℃; R0 is the film resistance at the reference temperature, measured during calibration; and α is the TCR, determined according to the material data sheet or calibration.

[0103] The gripping device or gripping array device of the present invention can work in conjunction with a multi-dimensional fusion (MLP) temperature control method implemented using a Field Programmable Gate Array (FPGA). The FPGA internally includes a temperature sensor preprocessing module, an MLP fusion temperature control method module, and a heating drive module. The MLP fusion temperature control method module includes an MLP feedforward prediction module and a PID fine-tuning module.

[0104] The temperature sensor preprocessing module receives N×M resistance signals and performs resistance-to-temperature conversion, median filtering, exponential smoothing filtering, and clamp 110 address encoding in parallel on each resistance signal, outputting N×M temperature feedback signals. Each temperature feedback signal includes the clamp 110 address identifier (ch_id) and the current temperature value (T_current). The feature construction module constructs a 7-dimensional feature vector x[7×1] based on each temperature feedback signal, the target temperature (T_target) sent by the host computer, the global ambient temperature (T_ambient), and the current temperature values ​​of adjacent clamps 110. This feature vector includes the normalized target temperature, the normalized current temperature, the normalized temperature rise rate, the normalized temperature deviation, the normalized average neighbor temperature, the normalized ambient temperature, and the PWM duty cycle of the previous control cycle.

[0105] The MLP feedforward prediction module learns the inverse thermal model of the controlled object, obtains a 16-dimensional hidden layer output through a first-level linear transformation and ReLU activation, and then obtains the feedforward duty cycle (duty_MLP) through a second-level linear transformation. The proportional gain (Kp_r) and integral gain (Ki_r) of the PID fine-tuning module are 1 / 5 to 1 / 10 of those of the pure PID controller, respectively, and output the fine-tuning duty cycle (duty_PID). The output fusion module adds and fuses the feedforward duty cycle and the fine-tuning duty cycle at the output end to obtain the final duty cycle: duty_final = clamp(duty_MLP + duty_PID, 0, 1), which is then output to the flexible electrothermal film of the gripper 110 after hard limiting to control the heating power of the gripper 110. The system also has an over-temperature emergency shutdown setting: when the current temperature value of any gripper 110 exceeds 90℃, the final duty cycle of the gripper 110 is set to 0 and a fault flag is triggered.

[0106] The MLP feedforward prediction module was trained offline: a training dataset was generated using COMSOL thermal simulation, covering 108 operating conditions, each including 64 channels × 600 steps of time series, totaling approximately 350,000 independent frames; a 7-16-1 structure MLP was constructed using PyTorch, with ReLU as the activation function, Adam as the optimizer, and Mean Squared Error (MSE) as the loss function for training; sensor noise of ±0.1℃ and electrothermal film resistance drift of ±10% were injected into the training data; the trained PyTorch model was converted sequentially to ONNX format and OpenVINO IR format, and after 16-bit fixed-point quantization compilation using FPGA AI Suite, a synthesizable RTL IP was generated and embedded into the Quartus project.

[0107] The N×M resistance signals are acquired through four 16-channel ADS7953 analog-to-digital converters and directly connected to the FPGA via an SPI interface. The FPGA synchronously controls the parallel sampling. The mapping relationship between the clamp 110 address code and the physical FPGA channel is written to the FPGA register during the deployment phase. The control cycle is 10ms, and the FPGA processes all N×M signals in parallel in a pipelined manner within each control cycle.

[0108] See Figure 5 The diagram shows the overall architecture of the temperature control system of the gripper 110 according to one embodiment.

[0109] like Figure 5 As shown, the overall architecture of the temperature control system includes: Figure 5 The HBM chip under test is placed horizontally on the left, with the solder balls facing down; below is the 3D photolithography gripper. The gripper 110 outputs a resistance value to... Figure 5The temperature sensor preprocessing module on the right; the FPGA internally includes a temperature sensor preprocessing module, an MLP fusion temperature control algorithm module, and a heating / cooling drive module. The MLP fusion temperature control algorithm module includes "MLP feedforward prediction" and "PID fine-tuning correction". The algorithm outputs a "temperature control signal" to the heating / cooling drive module, which in turn outputs a PWM signal to the gripper 110. The host computer control software interacts with the FPGA through a register interface, and the FPGA AISuite deploys the model to the FPGA through "update model".

[0110] Figure 5 The overall architecture of the gripper 110 temperature control system forms a closed-loop control chain of "sensing-decision-execution": the gripper 110's electrothermal film has both heating and self-temperature sensing functions. The resistance value is preprocessed to obtain a temperature feature vector, which is then fed into the MLP fusion temperature control method to output a temperature control signal. This signal is then used by the heating drive module to generate a PWM to drive the gripper 110. The host computer is responsible for non-real-time configuration monitoring, while the FPGA AI Suite is responsible for model updates and deployment.

[0111] The gripping device and its manufacturing method, gripping array device, and applications for two-photon lithography 3D printing provided by the embodiments of the present invention have at least one or a portion of the following advantages:

[0112] (1) The grippers of the gripping device of the present invention correspond to N×M micro bumps that contact the chip under test. Each hemispherical gripper includes a hemispherical body, a first conductive micropillar, a second conductive micropillar and multiple claws. The fingertips of the claws are used to contact the solder ball. A thermal driving layer, an insulating isolation layer, a heat insulation blocking layer, a conductive signal transmission layer, a stress buffer layer and an outer sheath layer are arranged sequentially from the solder ball outward. The first conductive micropillar penetrates from the side of the thermal driving layer near the solder ball to the conductive signal transmission layer. The second conductive micropillar is led out from the conductive signal transmission layer. The mesh microstrip structure of the thermal driving layer is only connected to the flexible electrothermal film and is insulated from the conductive signal transmission layer, so as to realize the separation of thermal driving and signal transmission circuit, while ensuring gripping reliability and high-speed signal integrity.

[0113] (2) The fingertip width is preferably 30μm, which is less than the minimum gap between the micro-bumps of 37μm, so that the gripper can be inserted between the micro-bumps and contact the solder ball, breaking through the bottleneck that traditional mechanical linkages cannot be arranged; the fingertip height is preferably 80μm, covering the height of the micro-bumps by 35μm and leaving a margin; the total thickness of the multi-layer functional structure is preferably 53μm, covering the height of the micro-bumps by 35μm and having a structural margin of 18μm to ensure reliable clamping;

[0114] (3) The thickness of the thermal drive layer is preferably 8μm. The liquid crystal elastomer nanofibers are oriented and arranged by an electric field, and generate 2~5μm of directional contraction in the temperature range of 40~90℃, so that the fingertip generates a clamping force of 0.1~0.3N, realizing the opening and closing by the thermal expansion and contraction of the material itself without the need for external mechanical drive; the in-plane conductive network is constructed by silver-plated graphene sheets, and the first conductive micropillar passes through the mesh of the mesh microstrip line structure and directly contacts the solder ball, ensuring that the circuit of thermal drive and signal transmission does not contact each other;

[0115] (4) The thickness of the insulating isolation layer is preferably 5μm, the breakdown strength is greater than 300kV / mm, and the withstand voltage is greater than 1.5kV to prevent short circuit between the thermal drive layer and the conductive signal transmission layer; in particular, to prevent short circuit between the mesh microstrip structure of the thermal drive layer or the heating drive signal and the conductive signal transmission layer that transmits the solder ball test signal; the hollow silica nanospheres reduce the dielectric constant to 2.0 and reduce the parasitic capacitance of the signal; the aperture of the photolithographic opening is preferably 8μm, and the space between the micropillar and the hole wall is filled with insulating glue for sealing;

[0116] (5) The thickness of the thermal insulation barrier layer is preferably 8 μm, which is composed of 100 cycles of alternating stacked atomic layer deposited alumina thin film and silica aerogel, with an equivalent thermal conductivity of 0.005 W / (m·K) and a thermal resistance of 1.6 K·m. 2 / W, blocks the heat from the microbumps from being transmitted to the conductive signal transmission layer, preventing high temperature from damaging the signal layer;

[0117] (6) The thickness of the conductive signal transmission layer is preferably 15 μm, and the characteristic impedance of the signal transmission line structure is 50Ω±2Ω, supporting a signal transmission rate of more than 32Gbps; the negative expansion nanopowder of zirconium tungstate reduces the coefficient of thermal expansion to less than 30ppm / ℃, ensuring impedance stability when the temperature fluctuates.

[0118] (7) The thickness of the stress buffer layer is preferably 12 μm and the elastic modulus is 50 MPa, which is between about 2 GPa of the conductive signal transmission layer and about 3 GPa of the outer sheath layer. It can be compressed and deformed by 2 μm during thermal cycling or mechanical vibration, eliminating interface stress concentration and protecting the rigid layer from cracking.

[0119] (8) The outer sheath layer is preferably 5μm thick, and the nickel-plated carbon fiber forms a three-dimensional network, which has a shielding effectiveness of 40dB against 20GHz electromagnetic waves, providing electromagnetic shielding and mechanical protection to prevent the internal structure from being mechanically damaged or chemically corroded.

[0120] (9) The first and second conductive micropillars are composed of silver-plated copper nanowires and polyimide precursor binder. The diameter is preferably 10 μm, the column spacing matches the staggered arrangement spacing of the HBM microbump array, the total height is greater than 36 μm, the single column resistance is 0.5 mΩ, and the bulk resistivity is 3 × 10⁻⁶. -5Ω·cm, ensuring high conductivity of the vertical signal channel and matching with the HBM micro-bump array;

[0121] (10) Using two-photon lithography, through hydrogel preparation, femtosecond light sheet patterning, pre-shrinking, regional selective material deposition, cleaning and drying and imaging observation, the manufacturing of micro-nano-level 3D complex material grippers can be realized. The pre-shrinking ratio can reach 13 times, breaking through the limitation of traditional processing technology that cannot manufacture micron-level complex material parts.

[0122] (11) Region-selective material deposition includes size-selective assembly. By adjusting the intensity of the femtosecond laser, the density of the hydrogel structure is controlled, and different component materials are deposited in different regions to form multi-layer functional structures, especially the mesh microstrip structure that forms the thermally driven layer, so as to realize the integrated manufacturing of multiple materials.

[0123] (12) The gripper array device includes a substrate and N×M grippers, with a second conductive micropillar array arranged and the pillar spacing matching the staggered arrangement spacing of the HBM microbump array, supporting large-scale parallel testing and meeting the high-density, high-parallel testing requirements of HBM.

[0124] (13) There are 8192 grippers, divided into four areas, with 2048 grippers in each area; the outer wall is attached with a flexible electric heating film that has both heating and self-temperature sensing functions, with a resistance of 10~50Ω, so that each gripper can have independent temperature feedback; the flexible electric heating film is electrically connected to the mesh microstrip structure of the heat-driven layer and is insulated from the conductive signal transmission layer.

[0125] (14) One end of the flexible electrothermal film is connected to the mesh microstrip structure of the thermal drive layer, and the other end is connected to the heating control circuit on the substrate; the signal lead-out line on the substrate is electrically connected to the signal transmission line structure of the second conductive micropillar or the conductive signal transmission layer, and transmits the test signal received by the signal transmission line structure to the external test equipment; the flexible electrothermal film is insulated from the conductive signal transmission layer to avoid short circuit; a thermoelectric cooler is set under the substrate to keep the substrate temperature constant at 15°C, providing a cold plate basis for the differential heating of the gripper;

[0126] (15) In the HBM test, the fingertips of N×M hemispherical grippers contact the solder balls of N×M microbumps respectively. The first conductive micropillar transmits the test signal of the microbumps to the second conductive micropillar through the signal transmission line structure, and then transmits it to the external test equipment. At the same time, the thermal drive layer controls the clamping or releasing of the grippers according to the temperature change. The mesh microstrip structure of the thermal drive layer is only connected to the flexible electrothermal film and not connected to the conductive signal transmission layer, so as to realize the high density, high speed and high reliability transmission of the microbump signal without damaging the signal layer.

[0127] While some embodiments of the present general inventive concept have been shown and described, those skilled in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the present general inventive concept, the scope of which is defined by the claims and their equivalents.

Claims

1. A gripping device for two-photon lithography 3D printing, the gripping device comprising N×M hemispherical grippers, each gripper correspondingly contacting solder balls on N×M microbumps of the chip under test, characterized in that, Each of the grippers includes a hemispherical body, a first conductive micropillar and a second conductive micropillar disposed at the lower end of the hemispherical body, and a plurality of grippers distributed along the circumference of the gripper, wherein the end of each gripper forms a fingertip for contacting the solder ball. Each of the grippers is provided with a multi-layered functional structure from the side that contacts the solder ball outwards. The multi-layered functional structure includes, in sequence, a thermal drive layer, an insulating isolation layer, a heat insulation blocking layer, a conductive signal transmission layer, a stress buffer layer, and an outer sheath layer. The thermally driven layer is disposed on the side near the solder ball in the form of a mesh microstrip line structure, having mesh holes through which the first conductive micropillars pass. The mesh microstrip line structure is configured to be electrically connected to a flexible electrothermal film for heating and / or temperature sensing. The thermally driven layer is configured to generate microscale deformation within the chip test temperature range so that the fingertip generates a clamping force to clamp or release the solder ball. The insulating isolation layer is configured to prevent short circuits in the conductive path between the thermally driven layer and the conductive signal transmission layer. The heat insulation barrier layer is configured to block the heat generated by the solder ball from being conducted to the conductive signal transmission layer. The conductive signal transmission layer includes a signal transmission line structure configured to transmit the test signal of the micro-bumps; The stress buffer layer is configured to absorb mechanical stress and provide an elastic modulus transition. The first conductive micropillar penetrates the thermally driven layer, the insulating isolation layer, and the thermal insulation blocking layer from the side of the thermally driven layer near the solder ball and enters the conductive signal transmission layer. The top end of the first conductive micropillar is in direct contact with the solder ball, and the bottom end of the first conductive micropillar is electrically connected to the signal transmission line structure. The second conductive micropillar is electrically connected to the signal transmission line structure of the conductive signal transmission layer and is configured to transmit the test signal received by the signal transmission line structure to an external test device.

2. The gripping device according to claim 1, characterized in that, The first conductive micropillar passes through the gap space of the signal transmission line structure and is wrapped and fixed by an insulating dielectric material; The signal transmission line structure includes a top-layer signal line, a middle dielectric layer, and a bottom-layer ground layer; The bottom end of the first conductive micropillar is electrically connected to the top layer signal line, and the first conductive micropillar is insulated from the intermediate dielectric layer and the bottom ground layer.

3. The gripping device according to claim 2, characterized in that, The second conductive micropillar is electrically connected to the top layer signal line of the signal transmission line structure; The flexible electrothermal film is electrically connected to the mesh microstrip structure of the thermally driven layer, and the flexible electrothermal film is insulated from the conductive signal transmission layer.

4. The gripping device according to claim 3, characterized in that, The width of the fingertip is 25~35μm, and the height is 75~85μm; The total thickness of the multilayer functional structure is 50~55μm.

5. The gripping device according to claim 3, characterized in that, The thickness of the thermally driven layer is 5~10μm; By weight percentage, the thermally driven layer comprises 50% liquid crystal elastomer nanofibers, 30% silver-plated graphene sheets, 15% liquid metal microdroplets, and 5% silane coupling agent; wherein, The liquid metal microdroplets are gallium-indium-tin alloys with a particle size of 2~5μm; The liquid crystal elastomer nanofibers are oriented and aligned by an electric field, and generate 2-5 μm of directional contraction in a temperature range of 40-90℃, so that the fingertip generates a clamping force of 0.1-0.3N. The silver-plated graphene sheet is used to construct an in-plane conductive network, which forms the mesh microstrip structure of the thermally driven layer. The first conductive micropillar passes through the mesh of the mesh microstrip structure and is in direct contact with the solder ball.

6. The gripping device according to claim 3, characterized in that, The thickness of the insulating layer is 2~8μm; By mass percentage, the insulating layer consists of 80% fluorinated polyimide, 15% hollow silica nanospheres and 5% silane coupling agent, wherein the particle size of the hollow silica nanospheres is 15~25nm. The breakdown strength of the insulating layer is greater than or equal to 300kV / mm, and the withstand voltage is greater than or equal to 1.5kV. The insulating layer has a photolithographic opening at the penetration point of the first conductive micropillar, the diameter of the photolithographic opening is 5~10μm, and the space between the first conductive micropillar and the wall of the photolithographic opening is filled with insulating adhesive.

7. The gripping device according to claim 3, characterized in that, The thickness of the heat insulation barrier layer is 5~10μm, which is composed of 100 cycles of alternating stacking of atomic layer deposited alumina film and silica aerogel, with a total thickness of 550~650nm, and the remaining thickness is filled by polyimide aerogel. The equivalent thermal conductivity of the heat insulation barrier layer is 0.005 W / (m·K), and the thermal resistance is 1.6 K·m. 2 / W.

8. The gripping device according to claim 3, characterized in that, The thickness of the conductive signal transmission layer is 10~20μm; By weight percentage, the conductive signal transmission layer consists of 35% fluorinated liquid crystal elastomer, 15% zirconium tungstate negative expansion nanoparticles, 30% silver-plated hollow glass microspheres, 10% silver-plated carbon nanotubes, 5% hollow silica nanospheres and 5% crosslinking agent. The signal transmission line structure includes a top layer signal line, an intermediate dielectric layer, and a bottom layer ground layer. The top-layer signal line is a silver-plated polyimide nanofiber signal line with a line width of 5~10μm and a thickness of 1~5μm; The thickness of the intermediate dielectric layer is 5~15μm, and the dielectric constant is 2.0; The bottom grounding layer is a silver-plated graphene grounding layer with a thickness of 1~5μm; The characteristic impedance of the signal transmission line structure is 50Ω±2Ω, supporting a signal transmission rate of greater than or equal to 32Gbps. The zirconium tungstate negative expansion nanopowder reduces the thermal expansion coefficient of the conductive signal transmission layer to less than 30 ppm / ℃; The bottom end of the first conductive micropillar and the second conductive micropillar are electrically connected to the top layer signal line, respectively, and the first conductive micropillar is insulated and isolated from the intermediate dielectric layer and the bottom ground layer.

9. The gripping device according to claim 3, characterized in that, The thickness of the stress buffer layer is 10~15μm; By weight percentage, the stress buffer layer consists of 70% thermoplastic polyurethane elastomer nanofilm, 25% silica aerogel micropowder and 5% crosslinking agent. The stress buffer layer has an elastic modulus of 45~55MPa and is configured to compress and deform by 1~5μm under thermal cycling or mechanical vibration.

10. The gripping device according to claim 3, characterized in that, The thickness of the outer sheath layer is 3~8μm; By weight percentage, the outer sheath consists of 60% polyetheretherketone nanocoating, 30% nickel-plated carbon fiber and 10% manganese-zinc ferrite nanosheets. The nickel-plated carbon fiber forms a three-dimensional network within the outer sheath layer, providing a shielding effectiveness of 35~45dB against 20GHz electromagnetic waves.

11. The gripping device according to any one of claims 1-10, characterized in that, Both the first conductive micropillar and the second conductive micropillar are composed of silver-plated copper nanowires and polyimide precursor binder. The silver-plated copper nanowires have a diameter of 90~110nm, a length of 35~40μm, and are oriented vertically. The diameter of the second conductive micropillar is 8~12μm; The total height of the first and second conductive micropillars is greater than or equal to 36 μm, the single-pillar resistance is 0.5 mΩ, and the bulk resistivity is 3 × 10⁻⁶. -5 Ω·cm.

12. A method for manufacturing a gripping device for two-photon lithography 3D printing, the method being used to manufacture the gripping device according to any one of claims 1-11, characterized in that, The manufacturing method includes: Preparation of hydrogel substrates; The hydrogel substrate is patterned using femtosecond optical sheet patterning technology to form a three-dimensional pattern corresponding to the hemispherical gripper shape; The patterned hydrogel substrate is pre-shrinked, with a shrinkage ratio of 10 to 15 times. Region-selective material deposition is performed, sequentially depositing the thermally driven layer, the insulating isolation layer, the thermal insulation blocking layer, the conductive signal transmission layer, the stress buffer layer, the outer sheath layer, and the materials of the first conductive micropillar and the second conductive micropillar; The deposited structure is then cleaned and dried. Imaging observation was performed to obtain the gripping device.

13. The manufacturing method according to claim 12, characterized in that, In the step of performing region-selective material deposition. The region-selective material deposition includes size-selective assembly, which controls the density of the hydrogel structure by adjusting the intensity of the femtosecond laser, and deposits different component materials in different regions to form the multilayer functional structure.

14. A gripper array device for two-photon lithography 3D printing, characterized in that, The gripper array device includes: substrate; and A gripping device according to any one of claims 1-11 disposed on the substrate; N×M hemispherical gripper arrays are arranged, and the spacing between the second conductive micropillars of each gripper is matched with the staggered arrangement spacing of the HBM microbump array. The horizontal spacing of the HBM microbump array is 70μm and the vertical spacing is 110μm. The second conductive micropillar is configured to correspond to the signal lead-out lines on the substrate; The flexible electrothermal film is electrically connected to the mesh microstrip structure of the thermally driven layer, and is insulated from the conductive signal transmission layer.

15. The gripper array device according to claim 14, characterized in that, The total number of N×M hemispherical grippers is 8192, divided into four regions, with 2048 grippers in each region; Each of the grippers is also attached to a flexible electrothermal film on its outer wall. The flexible electrothermal film has heating and self-temperature sensing functions. The flexible electrothermal film is a purely resistive load with a resistance of 10~50Ω. The flexible electrothermal film is electrically connected to the mesh microstrip structure of the thermally driven layer, and the flexible electrothermal film is insulated from the conductive signal transmission layer by the insulating isolation layer.

16. The gripper array device according to claim 15, characterized in that, One end of the flexible electrothermal film is connected to the mesh microstrip structure of the thermal drive layer, and the other end is connected to the heating control circuit on the substrate. It is electrically connected to the second conductive micropillar or the signal transmission line structure of the conductive signal transmission layer. The signal lead-out line is configured to transmit the test signal received by the signal transmission line structure to an external test device. The flexible electrothermal film is insulated from the conductive signal transmission layer. A thermoelectric cooler is also provided below the substrate. The cold side of the thermoelectric cooler is attached to the bottom surface of the substrate, and the hot side is attached to the heat sink. The thermoelectric cooler is configured to keep the temperature of the substrate constant at 12~18℃.

17. An application of a two-photon lithography 3D printed gripper in HBM high-bandwidth memory testing, wherein the gripper is a gripper according to any one of claims 1-11 or a gripper manufactured by the manufacturing method according to any one of claims 12-13, characterized in that, The fingertips of N×M hemispherical grippers respectively contact the solder balls of N×M microbumps of the HBM chip under test. The first conductive micropillar transmits the test signal of the microbump to the second conductive micropillar through the signal transmission line structure, and then to the external test equipment. At the same time, the thermal drive layer controls the clamping or releasing of the grippers according to the temperature change.

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