A reusable extreme low temperature test fixture based on pogo pins and alumina

Abstract

The application discloses a reusable extremely low-temperature test fixture based on spring needle and aluminum oxide, and belongs to the technical field of chip testing. A test module is arranged in a cavity of a first shell. A ground coplanar waveguide wire and a to-be-tested chip are electrically connected to the upper surface of the test module, and a solder pad and the to-be-tested chip are electrically connected to the lower surface of the test module. A first radio frequency connector is electrically connected to the ground coplanar waveguide wire of the test module as a signal output end. A second shell is fixed below the first shell, and a support module is arranged in a cavity of the second shell. The lower surface of the support module is provided with a ground coplanar waveguide wire, and a second radio frequency connector is electrically connected to the ground coplanar waveguide wire of the support module as a signal input end. A vertical coaxial structure penetrates the cavities of the first shell and the second shell, the bottom end of the vertical coaxial structure is electrically connected to the ground coplanar waveguide wire of the support module, and the top end needle of the vertical coaxial structure is elastically electrically connected to the solder pad on the lower surface of the test module. The fixture can be used for testing under extremely low temperature (such as 54K), and has reusability, thereby reducing the test cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chip testing, and particularly relates to a reusable extremely low-temperature test fixture based on spring pins and aluminum oxide. BACKGROUND

[0002] In recent years, with the development of III-V semiconductor technology, monolithic microwave integrated circuit (MMIC) chips (hereinafter referred to as chips) have become an indispensable core component in the field of phased array radar and wireless communication systems. However, the yield of III-V semiconductors has not yet reached the ideal level of semiconductor technology, and any mistake in the process of chip flow will result in defects in the chip. Therefore, in order to ensure the performance and reliability of the chip, each chip must undergo strict electrical characteristic parameter testing to identify and eliminate potential defects.

[0003] The test fixture is a common chip testing method at present. The test fixture assembles and fixes the chip on the substrate, and the interface of the chip is led out to the printed circuit board through the bonding wire for performance testing. However, most of the current chip test fixtures weld the chip on the printed circuit board, and the test connector of the test fixture is also fixed and welded with the printed board, which makes it difficult to disassemble the test connector after testing, increasing the testing cost of the chip. At the same time, the conventional chip test temperature is mostly above minus 50 degrees. With the development of technology, more and more application scenarios require the chip to work at extremely low temperature, such as below minus 200 degrees. The traditional test fixture cannot be used at such extremely low temperature. This is because the traditional test fixture uses a PCB substrate, which has a large difference in thermal expansion coefficient with the gallium arsenide microwave chip. When the temperature changes greatly, thermal expansion and contraction will produce stress, causing the chip to crack and be unable to use. Therefore, how to test the microwave chip at extremely low temperature (below minus 200 degrees) while realizing the reuse of the test fixture and reducing the chip testing cost is a problem that needs to be solved at present. SUMMARY

[0004] Technical problems to be solved:

[0005] In order to avoid the shortcomings of the prior art, the application provides a reusable extremely low-temperature test fixture based on spring pins and aluminum oxide. The aluminum oxide high-temperature co-fired ceramic with a thermal expansion coefficient close to that of the microwave chip is used as the dielectric substrate to carry the chip to be tested. The spring pin is used as the test connector, which is connected to the chip to be tested through elastic compression, facilitating the disassembly and reuse of the test fixture. The application solves the problems of the existing test fixture that is difficult to test at extremely low temperature and difficult to disassemble and reuse after testing.

[0006] The technical scheme of the present application is: a reusable extremely low temperature test fixture based on spring pins and aluminum oxide, comprising: a first shell, a second shell, a test module, a support module, a vertical coaxial structure, a first radio frequency connector, and a second radio frequency connector.

[0007] A first cavity is arranged in the first shell for horizontally mounting the test module; the test module is a printed circuit board using aluminum oxide high-temperature co-fired ceramic as a medium substrate, the upper surface of which is provided with a ground coplanar waveguide and a chip to be tested, which are connected by gold wire bonding; the lower surface is provided with a solder pad and an electrically connected chip to be tested; the first radio frequency connector penetrates the side wall of the first shell, and the center pin is electrically connected to the ground coplanar waveguide of the test module.

[0008] The second shell is fixedly connected below the first shell, and a second cavity is arranged in the second shell for horizontally mounting the support module; the support module is a printed circuit board, and the lower surface is provided with a ground coplanar waveguide transmission line; the second radio frequency connector penetrates the side wall of the second shell, and the center pin is electrically connected to the ground coplanar waveguide of the support module.

[0009] The vertical coaxial structure is a signal connection structure in which a plurality of spring pins are arranged coaxially according to certain rules, and is used for signal switching between the support module and the test module; the vertical coaxial structure vertically penetrates the first cavity and the second cavity, and the bottom end is electrically connected to the ground coplanar waveguide of the support module, and the top needle is elastically electrically connected to the solder pad on the lower surface of the test module.

[0010] The tail ends of the first radio frequency connector and the second radio frequency connector are connected to the test instrument through a cable, the second radio frequency connector is used as the signal input end of the test fixture, and the first radio frequency connector is used as the signal output end of the test fixture.

[0011] Further technical schemes of the present application are: the vertical coaxial structure comprises: a signal spring pin for signal transmission, and a plurality of ground spring pins for ground shielding; the signal spring pin is located at the center; a plurality of ground spring pins are uniformly distributed on the same circumference of the signal spring pin as the center; the elastic needles of the signal spring pin and the ground spring pin are directed in the same direction, and are directed towards the test module.

[0012] Further technical schemes of the present application are: by adjusting the number of ground spring pins and the distance between the ground spring pins and the signal spring pins, the impedance characteristics of the vertical coaxial structure are adjusted.

[0013] A further technical solution of the application is that the first shell comprises a first shell body and a first shell cover; the first cavity is located in the first shell body and has an upward opening; a bottom wall of the first shell body is provided with a through hole connected to the first cavity and used for penetrating a needle end of the signal spring needle; a plurality of downward blind holes are uniformly distributed around the through hole of the bottom wall of the first shell body, the number and position of the blind holes are matched with the ground spring needle, and the blind holes are used for mounting the needle end of the ground spring needle; four corner positions of the bottom wall of the first shell body are provided with supporting legs, which are used for fixedly connecting with the second shell and ensuring the distance between the first shell and the second shell for installing the vertical coaxial structure.

[0014] A further technical solution of the application is that the second shell comprises a second shell body and a second shell cover; the second cavity is located in the second shell body and has a downward opening; a top wall of the second shell body is provided with a group of through holes matched with the vertical coaxial structure and vertically penetrating the second cavity, which are used for penetrating the vertical coaxial structure; four corner positions of the top of the second shell body are provided with mounting lugs matched with the four supporting legs of the first shell body, which are used for penetrating bolts and being threadedly connected with the supporting legs; the second shell cover covers the lower part of the second cavity and is fixedly connected with the second shell body.

[0015] A further technical solution of the application is that the supporting module is provided with a group of mounting holes matched with the vertical coaxial structure; a bottom end of the signal spring needle is electrically connected with the corresponding mounting through hole of the supporting module through soldering, and then is electrically connected with the ground coplanar waveguide transmission line on the lower surface of the supporting module; a bottom end of the ground spring needle is electrically connected with the corresponding mounting through hole of the supporting module through soldering; the needle end of the signal spring needle elastically abuts against the solder pad on the lower surface of the test module; the needle end of the ground spring needle is inserted into the blind hole of the first shell and is used for grounding.

[0016] A further technical solution of the application is that the test fixture further comprises a through-capacitor, the through-capacitor penetrates the side wall of the first shell, the through-capacitor is electrically connected with the chip to be tested on the test module through gold wire bonding, and the through-capacitor is connected with an external power supply.

[0017] A further technical solution of the application is that the first radio frequency connector and the second radio frequency connector are both SMA radio frequency connectors.

[0018] A further technical solution of the application is that the dielectric constant of the alumina high-temperature co-fired ceramic medium substrate of the test module is 9.8.

[0019] A further technical solution of the application is that the supporting module adopts Rogers RO3003 with a dielectric constant of 3.0 as a medium substrate.

[0020] Advantages

[0021] The application has the advantages that the reusable extremely low temperature test fixture based on spring needle and alumina supports a printed circuit board support module in a second shell, a printed circuit board test module in a first shell, and a chip under test welded to the test module, designs a radio frequency signal transmission line on the support module and the test module, and connects external test instruments through a frequency connector, so that the support module and the test module are connected in a vertical coaxial structure formed by spring needles to realize elastic vertical interconnection and signal transmission, thereby realizing electrical characteristic test of a microwave chip.

[0022] Compared with conventional chip test fixtures, the test module of the application uses alumina high-temperature co-fired ceramic as a dielectric substrate, and cooperates with the shell structure design for accommodating the test module and the support module and the elastic connection design of the spring needles, so that the test fixture can test the microwave chip under extremely low temperature conditions (below -200 degrees Celsius), and meanwhile avoids damage to the chip under test due to thermal expansion and contraction of the dielectric substrate under extremely low temperature conditions. The thermal expansion coefficient of the alumina high-temperature co-fired ceramic is 5*10 -6K , the thermal expansion coefficient of the commonly used Rogers of the printed circuit board is 17*10 -6K , the thermal expansion coefficient of silicon is 2.6*10 -6K , and the thermal expansion coefficient of gallium arsenide is 5.8*10 -6K Under extremely low temperature environment, the Rogers material is selected because of the large difference between the thermal expansion coefficients of the Rogers material and gallium arsenide and silicon, and the thermal stress and mechanical stress generated when the temperature changes, so that the microwave chip is broken under pressure. The thermal expansion coefficient of the alumina high-temperature co-fired ceramic is close to that of the commonly used microwave chip materials gallium arsenide and silicon, so that the thermal stress and mechanical stress caused by temperature change are reduced, the test module and the microwave chip form a good match, and the reliability and stability of the device are ensured.

[0023] The test fixture has reusability and saves test cost. First, the test fixture of the application can be applied to test microwave chips of various sizes without changing the main structure of the fixture, but only by replacing the test module. Specifically, the structure size of the connection between the test module and the chip under test is changed according to the size of the chip under test, so as to adapt to the test requirements of microwave chips of various sizes, which has high practicability. Second, the vertical coaxial structure formed by the spring needles is used to realize transmission of radio frequency signals, which not only has excellent signal transmission quality, but also facilitates disassembly of the test module because the spring needles and the test module for mounting the chip under test are in elastic contact, and the remaining parts are not damaged, so that the first shell, the second shell, the support module, the vertical coaxial structure, the first radio frequency connector, the second radio frequency connector, and the through-hole capacitor in the fixture have reusability, which greatly saves test cost.

[0024] The parts of the test fixture are fixedly connected, the test structure is stable, and the bias voltage can be conveniently adjusted through the through-hole capacitor connected to the chip test module. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall split structure of the reusable extremely low temperature test fixture based on the spring needle and aluminum oxide according to the application;

[0026] Figure 2 It is a schematic diagram of the first shell body structure in the embodiment of the application;

[0027] Figure 3 It is a schematic diagram of the second shell body structure in the embodiment of the application;

[0028] Figure 4 It is a top view of the vertical coaxial structure in the embodiment of the application;

[0029] Figure 5 It is a schematic diagram of the three-dimensional vertical interconnection structure simulation model between the vertical coaxial structure and the ground coplanar waveguide line and the ground coplanar waveguide line of the support module in the embodiment of the application;

[0030] Figure 6 It is Figure 5 The simulation results of the simulation model in the full-wave electromagnetic simulation software Ansys HFSS, namely the schematic diagram of the insertion loss and the return loss;

[0031] Figure 7 It is a layout schematic diagram of the lower surface of the support module in the embodiment of the application;

[0032] Figure 8 It is a layout schematic diagram of the upper surface of the test module in the embodiment of the application;

[0033] Figure 9 It is a schematic diagram of the small signal gain of a low-noise amplifier chip respectively at 54K, 77K, 218K and 297K in the application embodiment tested by the chip test fixture of the application;

[0034] Figure 10 It is a schematic diagram of the test results of the noise figure of a low-noise amplifier chip respectively at 54K, 77K, 218K and 297K in the application embodiment tested by the chip test fixture of the application;

[0035] Figure 11 It is a schematic diagram of the test results of the input return loss of a low-noise amplifier chip respectively at 54K, 77K, 218K and 297K in the application embodiment tested by the chip test fixture of the application;

[0036] Figure 12Fig. 2 shows the test results of the output return loss of a low-noise amplifier chip at 54K, 77K, 218K and 297K respectively, which are tested by the chip test fixture of the application in the application examples.

[0037] BRIEF DESCRIPTION OF DRAWINGS 1. first housing, 11. first housing body, 111. first cavity, 112. through hole, 113. blind hole, 114. support leg, 115. first radio frequency connector mounting main hole, 116. first radio frequency connector mounting auxiliary hole, 117. through-hole for a feed-through capacitor, 12. first housing cover, 2. second housing, 21. second housing body, 211. second cavity, 212. mounting ear, 213. second radio frequency connector mounting main hole, 214. second radio frequency connector mounting auxiliary hole, 215. signal pogo pin via hole, 216. ground pogo pin via hole, 22. second housing cover, 3. test module, 31. ground coplanar waveguide line of the test module, 32. solder pad, 33. gold wire, 34. chip under test solder pad, 35. wire, 36. ground shielding via hole of the test module, 4. support module, 41. ground coplanar waveguide line of the support module, 42. ground shielding via hole of the support module, 43. first through hole of the support module, 44. second through hole of the support module, 5. vertical coaxial structure, 51. signal pogo pin, 52. ground pogo pin, 6. first radio frequency connector, 7. second radio frequency connector, 8. feed-through capacitor. DETAILED DESCRIPTION

[0038] The embodiments described below are exemplary and are intended to be illustrative of the application and are not to be understood as limiting the application.

[0039] In the description of the application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0040] Referring to Figure 1 The application provides a reusable extremely low temperature test fixture based on pogo pins and aluminum oxide, which comprises a first housing 1, a second housing 2, a test module 3, a support module 4, a vertical coaxial structure 5, a first radio frequency connector 6, a second radio frequency connector 7, and a feed-through capacitor 8. It is used for testing the electrical characteristic parameters of a monolithic microwave integrated circuit chip and can be used in an extremely low temperature environment (such as 54K). It has the characteristics of being reusable. At the same time, the signal transmission is highly reliable and the test structure is stable.

[0041] See Figure 1 , 2 The first shell 1 is made of metal and includes a first shell body 11 and a first shell cover 12. The first shell body 11 has a first cavity 111 inside, such as... Figure 1 When the first shell body 11 is placed horizontally, the opening of the first cavity 111 faces upward. The test module 3 is horizontally installed inside the first cavity 111, and its shape matches that of the test module 3. The first shell cover 12 covers the first cavity 111. Threaded holes are machined at the same positions around the periphery of the first shell body 11 and the first shell cover 12. The first shell cover 12 and the first shell body 11 are fixedly connected by a set of bolts, thereby enclosing the test module 3 inside the first cavity 111.

[0042] The bottom of the first housing body 11 has a through hole 112 that vertically penetrates the first cavity 111 for passing through the signal spring pin 51 in the vertical quasi-coaxial structure 5. Four downward-facing blind holes 113 are evenly distributed around the through hole 112 to match the four grounding spring pins 52 in the vertical quasi-coaxial structure 5, thus allowing the pin tips of the grounding spring pins 52 to be installed one-to-one. One side wall of the first housing body 11 has a first RF connector mounting main hole 115 that penetrates the first cavity 111 for mounting a first RF connector 6. Symmetrically arranged on both sides of the first RF connector mounting main hole 115 are first RF connector mounting auxiliary holes 116 for fixing the first RF connector 6 to the mounting flange using fasteners, thereby achieving a fixed connection between the first RF connector 6 and the first housing body 11. The other side of the first housing body 11 has a through-hole capacitor mounting hole 117 that penetrates the first cavity 111 for mounting a through-hole capacitor 8 for adjusting the bias voltage. One end of the feedthrough capacitor 8 is electrically connected to the chip under test on the test module 3 via gold wire bonding, and the other end is connected to an external power supply. Support legs 114 are provided at the four corners of the bottom of the first housing 11 for fixed connection to the second housing 2. The support legs 114 ensure that the distance between the first housing 1 and the second housing 2 allows for the installation of a vertical quasi-coaxial structure 5.

[0043] See Figure 1 , 3 The second housing 2 is made of metal and is fixedly connected to the lower part of the first housing 1. The second housing 2 includes a second housing body 21 and a second housing cover 22. The second housing body 21 has a second cavity 211 inside, with the opening of the second cavity 211 facing downwards and away from the first housing 1. The support module 4 is horizontally installed in the second cavity 211, and its shape matches that of the support module 4. The second housing cover 22 covers the lower part of the second cavity 211 and is fixedly connected to the second housing body 21. Specifically, threaded holes are machined at the same position around the circumference of the second housing body 21 and the second housing cover 22. The second housing cover 22 is fixedly connected to the second housing body 21 by bolts, thereby enclosing the support module 4 in the second cavity 211.

[0044] The second shell body 21 is provided with mounting lugs 212 at the top four corners, which are matched with the four supporting legs 114 of the first shell body 11, and are used for threaded connection with the supporting legs 114 through bolts. Specifically, the mounting lugs 212 are provided with mounting through holes, and the bottom center of the supporting legs 114 is provided with mounting threaded holes. The bolts are sequentially connected from bottom to top with the mounting lugs 212 and the supporting legs 114 to realize the fixed connection of the second shell body 21 and the first shell body 11.

[0045] The top wall of the second shell body 21 is provided with a group of through holes which are matched with the vertical coaxial structure 5 and vertically pass through the second cavity 211, and are used for passing through the vertical coaxial structure 5. Specifically, the group of through holes includes a signal spring needle through hole 215 for the signal spring needle 51 in the vertical coaxial structure 5 to pass through, and four ground spring needle through holes 216 for the four ground spring needles 52 in the vertical coaxial structure 5 to pass through.

[0046] One side wall of the second shell body 21 is provided with a second radio frequency connector mounting main hole 213 which penetrates the second cavity 211 and is used for mounting the second radio frequency connector 7. The second radio frequency connector mounting main hole 213 is symmetrically provided with second radio frequency connector mounting auxiliary holes 214 on both sides, which are used for fixed connection with the mounting flanges of the second radio frequency connector 7 through fasteners, so as to realize the fixed connection of the second radio frequency connector 7 and the second shell body 21.

[0047] Referring to Figure 1 , 5, 7, the support module 4 is made of Rogers RO3003 with dielectric constant of 3.0 as the medium substrate, the thickness is 2.5mm, and is horizontally installed in the second cavity 211 of the second shell 2. The lower surface of the support module 4 is provided with a ground coplanar waveguide 41 with a width of 2mm. The second radio frequency connector 7 penetrates the second radio frequency connector mounting main hole 213 of the second shell body 21, the center needle is electrically connected with the ground coplanar waveguide 41 of the support module 4, realizes waveguide signal input, and serves as the signal input port of the test fixture. The support module 4 is also provided with a set of mounting holes matched with the vertical coaxial structure 5, specifically including a support module first through hole 43 and a support module second through hole 44. The support module first through hole 43 has a hole diameter of 1mm, is used for mounting the bottom end of the signal spring needle 51 of the vertical coaxial structure 5, and is fixed by soldering, so as to realize electrical connection with the ground coplanar waveguide 41 of the support module 4. The support module second through hole 44 has a hole diameter of 1.2mm, is used for mounting the bottom end of the ground spring needle 52 of the vertical coaxial structure 5, and is fixedly connected with the support module second through hole 44 by soldering. The support module 4 is provided with a plurality of ground shielding vias 42 with a hole diameter of 0.2mm on both sides and the periphery of the ground coplanar waveguide 41. The ground shielding vias 42 are filled with conductive materials such as copper, realize grounding by contacting the second shell 2, and make the upper and lower ground surfaces of the support module 4 realize consistent grounding performance.

[0048] Referring to Figure 1 、 5, 8, the test module 3 is horizontally installed in the first cavity 111 of the first shell 1, and the test module 3 is a printed circuit board made of a dielectric substrate of aluminum oxide high-temperature co-fired ceramic with a dielectric constant of 9.8, and the thickness is 1.5mm. The upper surface of the test module 3 is provided with a ground coplanar waveguide line 31 with a width of 0.7mm, and the chip under test is installed on the upper surface of the test module 3 through the setting pad 34, and the chip under test and the ground coplanar waveguide line 31 on the upper surface of the test module 3 are connected through gold wire bonding. The first radio frequency connector 6 penetrates the first radio frequency connector mounting hole 115 of the first shell body 11, and the center needle is electrically connected with the ground coplanar waveguide line 31 of the test module 3, which is used to realize waveguide signal output and is used as the signal output port of the test fixture. At the same time, the test module 3 is provided with a through hole, and the through hole is provided with a pad 32 at both ends, and the pad 32 on the upper surface of the test module 3 is connected with the chip under test through the gold wire 33 bonding, and the pad 32 on the lower surface of the test module 3 is elastically abutted with the needle head end of the signal spring needle 51 of the vertical coaxial structure 5 to realize electrical connection. The upper surface of the test module 3 is provided with a wire 35, and the wire 35 is connected with the chip under test through gold wire bonding, which is used to provide power supply. The ground coplanar waveguide line 31 on both sides of the test module 3 and the edge of the test module 3 are provided with a plurality of ground shielding vias 36 with a diameter of 0.2mm, and the ground shielding vias 36 are filled with conductive materials such as copper, which realizes grounding by contacting with the first shell 1, so that the upper and lower ground surfaces of the test module 3 are connected to realize consistent grounding performance.

[0049] Referring to Figure 1 、 4 , 5 the vertical coaxial structure 5 is a signal connection structure in which a plurality of spring needles are arranged coaxially according to certain rules, which is used to support the signal transfer between the support module 4 and the test module 3. In this embodiment, the vertical coaxial structure 5 includes: a signal spring needle 51 for signal transmission, and four ground spring needles 52 for ground shielding. The signal spring needle 51 is located at the center position, and the four ground spring needles 52 are uniformly distributed on the same circumference of the signal spring needle 51 with the signal spring needle 51 as the center, the center distance between the signal spring needle 51 and the ground spring needle 52 is 2.5mm, and the diameter of the signal spring needle 51 is 0.9mm. Further, the ground coplanar waveguide transmission line with a certain width of the support module 4 and the test module 3 is connected and impedance matched, and modeling simulation is carried out in ANSYSHFSS simulation software, so as to match the characteristic impedance of 50Ω. As Figure 6As shown, it can be seen that the test structure of the application has excellent radio frequency transmission, low insertion loss and small reflection. It should be noted that the arrangement of the spring pins of the vertical coaxial structure 5 presented in the application is only one of many arrangements. By adjusting the number of ground spring pins 52, the arrangement of the peripheral ground spring pins 52 and the distance between the central position signal spring pins 51, the impedance characteristics of the vertical coaxial structure 5 are adjusted to match the ground coplanar waveguide transmission line connection and impedance of the support module 4 and the test module 3, so that the entire chip test fixture has good radio frequency signal transmission characteristics.

[0050] The needle end of the signal spring pin 51 and the ground spring pin 52 faces the test module 3, and the bottom end of the signal spring pin 51 and the ground spring pin 52 faces the support module 4. Specifically, the vertical coaxial structure 5 vertically penetrates the cavities of the first shell 1 and the second shell 2, realizing signal connection between the support module 4 and the test module 3. The bottom end of the signal spring pin 51 and the four ground spring pins 52 respectively passes through the signal spring pin through hole 215 and the ground spring pin through hole 216 on the top of the second shell body 21, and enters the second cavity 211. The bottom end of the signal spring pin 51 is fixed by soldering with the first through hole 43 of the support module, and then realizes electrical connection with the ground coplanar waveguide line 41 of the support module 4. The bottom end of the four ground spring pins 52 is fixed by soldering with the second through hole 44 of the support module to realize electrical connection. The needle end of the signal spring pin 51 passes through the through hole 112 on the bottom of the first shell body 11 and elastically abuts against the pad 32 on the lower surface of the test module 3 to realize electrical connection, and the needle end of the four ground spring pins 52 is inserted into the four blind holes 113 on the bottom of the first shell body 11 to realize common ground.

[0051] The first radio frequency connector 6 and the second radio frequency connector 7 have the same structure model, both of which adopt the SMA-KFD1017 type radio frequency connector. The tail end of the first radio frequency connector 6 and the second radio frequency connector 7 is connected with the coaxial line interface of the test instrument, i.e. the vector network analyzer, through a cable, so that the second radio frequency connector 7 serves as the signal input port of the test fixture. The test signal is transmitted to the signal spring pin 51 through the ground coplanar waveguide line 41 of the support module 4, then transmitted to the pad 32 of the test module 3 through the elastic needle of the signal spring pin 51, and then transmitted to the chip to be tested, and then transmitted to the first radio frequency connector 6 through the ground coplanar waveguide line 31 of the test module 3. The first radio frequency connector 6 serves as the signal output port of the test fixture, and the electrical characteristic parameter test of the chip to be tested is realized through the test instrument.

[0052] The test fixture of the present application is a three-dimensional vertical interconnection low-temperature-resistant reusable chip test fixture based on spring needle and alumina high-temperature co-fired ceramic, which adopts a vertical coaxial structure 5 based on spring needle for signal transmission, and connects the support module 4 at the bottom of the test fixture and the test module 3 at the top through the spring needle. The medium substrate adopted by the test module 3 is alumina high-temperature co-fired ceramic, which can accurately test the electrical performance of the chip at extremely low temperature, meeting the current complex and variable chip application scene requirements. At the same time, the chip test fixture proposed in the present application has high efficiency and reusability. By replacing the test module 3 of the test fixture and matching the corresponding size of the chip to be tested, the test fixture can be reused, greatly reducing the test cost of the chip, so that the test fixture can be applied in various test scenes and has high practicability.

[0053] Test fixture use example of the present application:

[0054] A low-noise amplifier chip with a frequency range of 1-1.6GHz is selected and installed on the upper surface of the test module 3. In order to realize the drain bias of the low-noise amplifier chip, an 80pF through-hole capacitor 8 is connected, and the low-noise amplifier chip is connected with the pad 32, the ground coplanar waveguide 31 of the test module, the wire 35 and the 80pF through-hole capacitor 8 through gold wire bonding, realizing the connection of the radio frequency input end and the radio frequency output end to the test instrument, and verifying the test fixture of the present application. Referring to Figure 9 、 10 、11、12, it can be seen that the performance curves of the tested low-noise amplifier chip at different temperatures of 54K, 77K, 218K and 297K, such as small signal gain, noise figure, input return loss and output return loss, can be seen that the present application can accurately test the electrical performance at extremely low temperature, has excellent radio frequency transmission quality, good electrical performance, and meets the current complex and variable chip application scene requirements.

[0055] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those skilled in the art can make changes, modifications, replacements and variations to the above embodiments without departing from the principles and purposes of the present application within the scope of the present application.

Claims

1. A reusable ultra-low temperature test fixture based on spring pins and aluminum oxide, characterized by: The first shell, the second shell, the test module, the support module, the vertical coaxial structure, the first radio frequency connector, and the second radio frequency connector; The first shell is internally provided with a first cavity for horizontally mounting the test module; The test module is a printed circuit board using alumina high-temperature co-fired ceramic as a medium substrate, and the upper surface of the test module is provided with a ground coplanar waveguide and a chip to be tested, and the two are connected by gold wire bonding; The lower surface of the test module is provided with a solder pad and an electrically connected chip to be tested; the first radio frequency connector penetrates the side wall of the first shell, and the center needle is electrically connected with the ground coplanar waveguide of the test module; The second shell is fixedly connected below the first shell, and the second shell is internally provided with a second cavity for horizontally mounting the support module; the support module is a printed circuit board, and the lower surface of the support module is provided with a ground coplanar waveguide; the second radio frequency connector penetrates the side wall of the second shell, and the center needle is electrically connected with the ground coplanar waveguide of the support module; The vertical coaxial structure is a signal connection structure in which a plurality of spring needles are coaxially arranged according to a certain rule, and is used for signal switching between the support module and the test module; the vertical coaxial structure vertically penetrates the first cavity and the second cavity, and the bottom end of the vertical coaxial structure is electrically connected with the ground coplanar waveguide of the support module, and the top needle of the vertical coaxial structure is elastically electrically connected with the solder pad on the lower surface of the test module; The tail ends of the first radio frequency connector and the second radio frequency connector are connected with a test instrument through a cable, the second radio frequency connector is used as a signal input end of a test fixture, and the first radio frequency connector is used as a signal output end of the test fixture.

2. The reusable ultra-low temperature test fixture based on spring pins and aluminum oxide of claim 1, wherein: The vertical coaxial structure includes: a signal spring needle for signal transmission, and a plurality of ground spring needles for ground shielding; the signal spring needle is located at the center position; the plurality of ground spring needles are uniformly distributed on the same circumference of the signal spring needle as the center; the needle heads of the signal spring needle and the ground spring needle are directed in the same direction, and are directed toward the test module.

3. The spring pin and alumina based reusable ultra-low temperature test fixture of claim 2, wherein: The number of ground spring needles and the distance between the ground spring needles and the signal spring needle are adjusted to adjust the impedance characteristics of the vertical coaxial structure.

4. The spring pin and alumina based reusable extremely low temperature test fixture of claim 2, wherein: The first shell includes a first shell body and a first shell cover; the first cavity is located in the first shell body and has an upward opening; the bottom wall of the first shell body is provided with a through hole communicating with the first cavity, for penetrating the needle head end of the signal spring needle; the through hole of the bottom wall of the first shell body is uniformly provided with a plurality of downward opening blind holes, the number and position of the blind holes are matched with the ground spring needles, and the blind holes are used for mounting the needle head end of the ground spring needle; the bottom wall of the first shell body is provided with support legs at four corner positions, for fixedly connecting with the second shell and ensuring the distance between the first shell and the second shell for mounting the vertical coaxial structure; and the first shell cover is covered above the first cavity and is fixedly connected with the first shell body.

5. The spring pin and alumina based reusable extremely low temperature test fixture of claim 4, wherein: The second shell comprises a second shell body and a second shell cover; the second cavity is located in the second shell body and has an opening downward; a top wall of the second shell body is provided with a group of through holes matched with the vertical coaxial structure and vertically penetrating the second cavity, for penetrating the vertical coaxial structure; four corner positions of the top of the second shell body are provided with mounting lugs matched with the four supporting legs of the first shell body, for penetrating the threaded connection with the supporting legs through bolts; the second shell cover is covered below the second cavity and fixedly connected with the second shell body.

6. The spring pin and alumina based reusable extremely low temperature test fixture of claim 5, wherein: The support module is provided with a group of mounting holes matched with the vertical coaxial structure; the bottom end of the signal spring needle is electrically connected with the support module through soldering of the corresponding mounting through hole, and then electrically connected with the ground coplanar waveguide line on the lower surface of the support module; the bottom end of the grounding spring needle is electrically connected with the support module through soldering of the corresponding mounting through hole; the needle end of the signal spring needle is elastically abutted with the pad on the lower surface of the test module; the needle end of the grounding spring needle is inserted into the blind hole of the first shell for grounding.

7. The spring pin and alumina based reusable extremely low temperature test fixture of claim 1, wherein: The test fixture further comprises a through-capacitor, the through-capacitor penetrates the side wall of the first shell, the through-capacitor is electrically connected with the chip to be tested on the test module through gold wire bonding, and the through-capacitor is externally connected with a power supply.

8. The spring pin and alumina based reusable extremely low temperature test fixture of claim 1, wherein: The first radio frequency connector and the second radio frequency connector are both SMA radio frequency connectors.

9. The spring pin and alumina based reusable extremely low temperature test fixture of claim 1, wherein: The dielectric constant of the alumina high-temperature co-fired ceramic medium substrate of the test module is 9.

8.

10. The spring pin and alumina based reusable extremely low temperature test fixture of claim 1, wherein: The support module uses Rogers RO3003 with a dielectric constant of 3.0 as a medium substrate.

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