Test fixture for microwave surface-mounted device
Through the micro-convex grounding design and the design of the L-shaped connector and the micro-convex test fixture body, the problems of poor testing performance, complex calibration and high cost in the existing microwave surface-mounted device testing methods are solved, and high-performance standing wave testing and rapid design and processing of wide bands are realized.
Patent Information
- Application Number
- CN202510316077.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-18
- Publication Date
- 2025-06-27
AI Technical Summary
The existing microwave surface-mounted device testing methods have problems such as poor device testing performance, complex loss and port standing wave calibration, and long design cycle and high cost of test fixtures.
The micro-convex grounding design and the design of the L-shaped connector and the micro-convex test fixture main body are used to realize efficient grounding and excellent standing wave testing of the surface-mounted micro-strip circulator.
The wide-band standing wave high-performance index test is realized, which reduces the design and processing cycle of the test fixture, reduces the cost, and improves the testing efficiency.
Smart Images
Figure CN120214375A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of microwave component testing, and particularly to a microwave surface-mounted device testing fixture. Background Art
[0002] Currently, when performing performance tests on microwave surface-mounted devices, such as coaxial surface-mounted circulators / isolation devices, PCB board conversion testing is generally adopted. The specific testing method is as follows: The connector is welded to the test board, and the device is converted to the contacts on the PCB board through a conductive film to achieve performance testing.
[0003] As Figure 1 and Figure 2 shown, it mainly includes a device under test 1, a vertical conductive film 2, a limit block 3, a multi-layer PCB test board 4, a single-port test connector 5, a dual-port test connector 6, and a test fixing base 7; among them, For the device under test 1 (taking a coaxial circulator as an example), the bottom coaxial transmission port is as Figure 3 shown, with a transmission contact 11 that functions to transmit signals, generally using a copper core ball or a high-lead tin ball; a circulator iron base plate 12 that functions to support the device substrate and form a 50-ohm impedance with the transmission contact 11 at the transmission point; the vertical conductive film 2 is a flexible film that functions to buffer and electrically transmit, realizing the electrical interconnection between the transmission points of the device under test and the test contacts of the multi-layer PCB test board; the limit block 3 is generally made of non-conductive plastic and functions to limit the device under test and the conductive film, generally processed from PEEK or PI; the multi-layer PCB test board 4 functions to perform electrical conversion from the test contacts to the connector. A coaxial surface-mounted circulator isolator is generally designed and processed using a three-layer PCB board. The multi-layer PCB test board and the test fixing base are generally soldered to achieve good grounding; the single-port test connector 5 functions to extract and transfer the test performance of the PCB test board to a network analyzer. The central conductor of the connector is interconnected with the transmission line of the PCB test board by welding; the dual-port test connector 6 functions to extract and transfer the test performance of the PCB test board to a network analyzer. The central conductor of the connector is interconnected with the transmission line of the PCB test board by welding; the test fixing base 7 functions to limit the installation of the connector, and limit the installation of the multi-layer PCB test board and the limit block, and is generally processed from brass.
[0004] The above-mentioned testing method and the used testing fixture have at least the following problems: (1). The device test performance is poor, mainly manifested in the poor port standing wave performance of the device. Generally, it is difficult to reach below 1.3 in a wide frequency band range, with large losses. The transmission loss of the vertical conductive film cannot be calibrated, resulting in excessive device loss testing. Generally, the vertical conductive film will introduce a loss of 0.1 - 0.3 dB, and the loss is even greater at high frequencies; (2). The calibration of loss and port standing wave is complex. For a multi-layer PCB test board, during testing, the test ports need to be calibrated to the contact positions of the multi-layer PCB test board. The TRL calibration method is complex, and the port standing wave calibration effect after calibration is not good;
[0005] (3). The simulation design of the test fixture. The test fixture not only needs to design the test board but also needs to be equipped with the design of the TRL calibration component. The design and processing cycle are long. Generally, it takes 10 - 20 days to produce a test fixture. The multi-layer test board of the coaxial surface-mount circulator isolator generally adopts a 3-layer board design. There are a large number of grounding vias and solid transmission vias in the design, and the processing is complex and the cost is high; (4). The cost of the test fixture is high. The vertical conductive film is an imported product. Currently, only Hitachi and Shin-Etsu Chemical in Japan can produce the vertical conductive film for high-frequency testing. The price is expensive, and the life of the vertical conductive film is short. The maximum number of tests is about 300. Calculated by the area of 10 * 10 for a single device, the average test cost of the conductive film for a single device using the Hitachi ACF2669JFP300 conductive film is about 2 yuan. Moreover, the PCB test board test fixture basically reaches the test life after using the vertical conductive film twice. Summary of the Invention
[0006] The purpose of the present invention is to provide a test fixture for microwave surface-mount devices to solve the above problems.
[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A test fixture for microwave surface-mount devices includes a micro-bump test fixture main body, a test connector, and a test connector fixing plate connected in sequence from top to bottom. Among them, a test cavity for installing the device under test is provided on the front surface of the micro-bump test fixture main body. A transmission contact balance micro-bump, a transmission contact test matching hole, and a device grounding micro-bump are provided in the test cavity. An installation cavity for installing the connector is provided on the back surface of the micro-bump test fixture main body, and a connector grounding micro-bump is provided in the installation cavity.
[0008] As a preferred technical solution, threaded holes are designed in the area of the installation connector position of the test connector fixing plate, and light holes are designed in the area of the micro-bump test fixture main body.
[0009] The grounding strengthening screw presses the test connector through the threaded hole mounting hole provided on the test connector fixing plate to play a role in strengthening grounding; the fixing screw passes through the light hole of the test connector fixing plate and is threadedly connected with the threaded hole on the micro-bump test fixture main body to lock and fix the connector fixing plate and the main body.
[0010] The fixing screw passes through the light hole of the test connector fixing plate and is threadedly connected with the threaded hole on the micro-bump test fixture main body.
[0011] The micro bump test fixture body plays a good role in grounding and positioning the device under test. At the same time, it provides an installation position and a matching transition for the test connector. The test connector plays a role in extracting and transmitting device signals. The test connector fixing plate plays a role in limiting the connector and provides a grounding strengthening screw installation hole. The connector grounding strengthening screw is used to provide external pressure for the good grounding of the connector. The fixing screw is used to fix the test connector fixing plate. The transmission contact balance micro bump plays a role in supporting and balancing the transmission contact test matching hole and grounding the iron base plate of the device under test. The transmission contact test matching hole plays a role in air matching of the test pins of the test connector and grounding around the device transmission contacts. The device grounding micro bump plays a role in grounding and supporting the iron base plate of the device under test. The connector grounding micro bump plays a role in supporting and grounding the test connector.
[0012] The present invention adopts a micro bump grounding design to achieve efficient grounding of the surface-mounted microstrip circulator, and adopts a design of an L-shaped connector plus a micro bump test fixture body to achieve excellent standing wave testing of the device test port.
[0013] The L-shaped connector is an existing bent connector, mainly to avoid interference of the test cable when the test cable is interconnected with the connector, or to add a lot of adapters, and it is also convenient for test wiring.
[0014] As a preferred technical solution: The test connector is preferably a connector with an L-shaped structure, which can realize reasonable and stable arrangement of the test cable, and the separable test connector can realize connector standardization. It can be arranged according to the contact position of the device under test, and only need to design a suitable installation position size on the test fixture body, and achieve adaptation by machining and modifying the shape of the test connector. To achieve alignment of the test pin and the matching hole, a through-wall boss can be machined on the test connector to achieve precise installation alignment. As a preferred technical solution: The device grounding micro bumps are reasonably arranged within the grounding surface range of the device under test. The positions of the device grounding micro bumps are symmetrically arranged. The diameter of the device grounding micro bumps is 0.5 mm to 1 mm, the height of the device grounding micro bumps is 0.01 mm to 0.03 mm, the interval between the device grounding micro bumps is 0.6 mm to 2 mm, and the distance between the device grounding micro bumps and the edge of the device test cavity is 0.3 mm to 0.6 mm.
[0015] The purpose of limiting the diameter and height of the above-mentioned device grounding micro bumps is that the device grounding micro bumps with such dimensions have good grounding effects, and general machining can be achieved without using expensive machining means such as electrical discharge machining. The purpose of defining the intervals between the device grounding micro-bumps and their distances from the cavity edge is as follows: According to the performance requirements of the device, the sizes of the grounding points with higher performance requirements are smaller and the quantities are larger. The defined intervals and distances from the cavity edge can be achieved by general machining, without using expensive machining means such as electrical discharge machining; being too far from the cavity edge will result in poor grounding effect at the bottom edge during device testing.
[0016] Since there are three transmission contacts on the device, to ensure the force balance of the device during testing, it is preferred to adopt the method of setting a transmission contact balance micro-bump to balance the other three transmission contacts. All the contacts in the test cavity play a grounding role.
[0017] The number of device grounding micro-bumps is generally determined by the device size in combination with the arrangement of transmission contacts and the machining ability. Generally, the number of device grounding micro-bumps is set to more than 10.
[0018] The position of the transmission contact balance micro-bump is at the other point of the rectangle formed by the three transmission contacts, and the sides of the rectangle are parallel to the outer shape sides of the device.
[0019] The transmission contact test matching holes are concentrically arranged with the device transmission contacts and are at the same height as the grounding micro-bumps.
[0020] As a preferred technical solution: The connector grounding micro-bumps are reasonably arranged within the range of the connector grounding surface. The positions of the connector grounding micro-bumps are symmetrically arranged. The diameter of the connector grounding micro-bumps is 0.5 mm to 1 mm, the height of the connector grounding micro-bumps is 0.01 mm to 0.07 mm, the intervals between the connector grounding micro-bumps are 0.6 mm to 2 mm, and the minimum distance between the connector grounding micro-bumps and the edge of the installation cavity is 0.3 mm.
[0021] As a preferred technical solution: The main body of the micro-bump test fixture is processed with H62 material and is surface passivated or gold-plated. Generally, only surface passivation treatment is adopted for general conventional tests. Gold plating treatment is mainly to improve the wear resistance of the test fixture and extend its service life; reduce the contact resistance between the test fixture and the device under test, improve the electrical conductivity, and enhance the test performance.
[0022] The passivation treatment is to use chemical reagents to treat the surface of brass to form an oxide film to prevent corrosion. The specific treatment method is a well-known method in the prior art.
[0023] Compared with the prior art, the advantages of the present invention are as follows: (1). When the transmission interface is clear, the present invention can only perform matching design between the test pins of the connector and the transmission contacts. Since the matching transition section has a simple structure of air coaxial, the simulation and optimization time of the test fixture is greatly reduced. Generally, the simulation and the structural design of the test fixture can be completed in half a day, and the processing of the test fixture can generally be controlled to be completed within 2 days (while the fixture simulation design using the PCB board test technology takes 2 - 3 days, and the processing cycle of the PCB board is about 7 days, and the longest time can reach 15 days). It realizes the rapid design and processing of the test fixture for the coaxial surface-mounted microstrip circulator, improving the design efficiency and processing efficiency compared with the traditional PCB board transfer test; (2). The present invention converts the loss of the vertical conductive film into the loss of the connector, which can greatly reduce the fixture cost in device testing; the service life of the test connector is much higher than the effective test life of the vertical conductive film. The effective test life of the connector is 800 - 1000 pieces. Calculated by testing 800 devices, the test cost of the connector test is 0.15 yuan, which is greatly reduced compared with the test cost of 2 yuan for the conductive film; (3). The present invention can achieve high-performance test of the standing wave in a wide frequency band. As Figure 8 shown, the standing wave test data of one port of the device is lower than 1.15 in the frequency band of 4 - 18 GHz; the standing wave of the port tested by the conductive film is as Figure 9 shown, and the best standing wave test data is lower than 1.2 in the frequency band of 4 - 18 GHz; (4). The present invention can eliminate the TRL calibration and only needs to calibrate the loss of the two connectors, reducing the calibration time of the test. The TRL calibration time is about 10 minutes, and the calibration duration of the loss of the two connectors is short, which can be completed within 1 minute. Description of the Drawings
[0024] Figure 1 is a schematic structural diagram of a traditional test fixture for surface-mounted devices; Figure 2 is Figure 1 an exploded schematic diagram; Figure 3 is a schematic diagram of the bottom transmission port of a coaxial surface-mounted circulator; Figure 4 is a structural diagram of the coaxial surface-mounted circulator isolator micro bump grounding test fixture of the present invention; Figure 5 is Figure 4 an exploded schematic diagram; Figure 6 is Figure 5 a front schematic diagram of the main body of the micro bump grounding test fixture in Figure 7 is Figure 5 a back schematic diagram of the main body of the micro bump grounding test fixture in Figure 8The standing wave test curve of the microbump test fixture port for the embodiment of the present invention; Figure 9 The standing wave test curve of the test fixture port for the conductive film solution; Figure 10 The back schematic diagram of the general assembly drawing of the microbump test fixture for the embodiment of the invention; In the figure: 1. Device under test; 11. Transmission contact; 12. Circulator iron base plate; 2. Vertical conductive film; 3. Limit block; 4. Multilayer PCB test board; 5. Single-port test connector; 6. Dual-port test connector; 7. Test fixing base; a. Microbump test fixture main body; a1. Transmission contact balance microbump; a2. Transmission contact test matching hole; a3. Device ground microbump; a4. Connector ground microbump; b. Test connector; c. Test connector fixing plate; d. The connector ground strengthening screw; e. Fixing screw. Specific implementation manner
[0025] The present invention will be further described below in conjunction with embodiments.
[0026] Embodiment 1: A microwave surface-mounted device test fixture, as Figure 4 and Figure 5 shown, includes a microbump test fixture main body a, a test connector b, and a test connector fixing plate c that are connected in sequence from top to bottom. A ground strengthening screw d is further provided on the bottom surface of the test connector fixing plate c, and corresponding ground strengthening screw mounting holes are provided on the test connector fixing plate c; A fixing screw e is also provided, wherein, as Figure 6 and Figure 7 shown, a test cavity for mounting the device under test is provided on the front surface of the microbump test fixture main body a. A transmission contact balance microbump a1, a transmission contact test matching hole a2, and a device ground microbump a3 are provided in the test cavity. An installation cavity for mounting the connector is provided on the back surface of the microbump test fixture main body, and a connector ground microbump a4 is provided in the installation cavity, In this embodiment, the test connector b is a connector with an L-shaped structure; The device ground microbump a3 is arranged in a symmetric structure, with a diameter of 0.8 mm, a height of 0.03 mm, a spacing of 0.9 mm between the device ground microbumps a3, a distance of 0.6 mm between the device ground microbump a3 and the edge of the device test cavity, and the size of the test cavity is 7.5 mm * 6.4 mm; The grounding micro-bumps a4 of the connector are arranged in a symmetric structure, with a diameter of 1.0 mm, a height of 0.05 mm, and a spacing between the grounding micro-bumps a4 of the connector of 1 - 3 mm; the minimum distance between the grounding micro-bumps a4 of the connector and the edge of the connector mounting cavity is 0.75 mm.
[0027] The main body of the micro-bump test fixture in this embodiment is processed from H62 material and undergoes surface passivation treatment; The port standing wave test curve of the micro-bump test fixture in this embodiment is as Figure 8 shown. It can be seen from Figure 8 that within the wide frequency band range of 4 - 18 GHz, the measured port standing wave is lower than 1.15.
[0028] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.
Claims
1. A microwave surface mount device test fixture, characterized in that: The invention comprises a micro-bump test fixture body, a test connector and a test connector fixing plate which are connected in sequence from top to bottom, wherein a test cavity for installing a device under test is arranged on the front side of the micro-bump test fixture body, transmission contact balancing micro-bumps, transmission contact test matching holes and device grounding micro-bumps are arranged in the test cavity, and an installation cavity for installing a connector is arranged on the back side of the micro-bump test fixture body, and a connector grounding micro-bump is arranged in the installation cavity.
2. The microwave surface mount device test fixture according to claim 1, characterized in that: A grounding reinforcement screw is also arranged on the bottom surface of the test connector fixing plate, and a corresponding grounding reinforcement screw mounting hole is arranged on the test connector fixing plate; a fixing screw is also arranged.
3. The microwave surface mount device test fixture according to claim 1, characterized in that: The test connector is an L-shaped connector.
4. The microwave surface mount device test fixture according to claim 1, characterized in that: The device grounding micro-bumps are arranged in a symmetrical structure, with a diameter of 0.5 mm to 1 mm and a height of 0.01 to 0.03 mm.
5. The microwave surface mount device test fixture according to claim 4, characterized in that: The spacing between the device grounding micro-bumps is 1~2mm, and the distance between the device grounding micro-bumps and the edge of the device test cavity is 0.3mm~0.6mm.
6. The microwave surface mount device test fixture according to claim 1, characterized in that: The connector grounding micro-bumps are reasonably arranged within the range of the connector grounding surface. The positions of the connector grounding micro-bumps are symmetrically set. The diameter of the connector grounding micro-bumps is 0.5mm~1mm, the height of the connector grounding micro-bumps is 0.01mm~0.07mm, the spacing between the connector grounding micro-bumps is 0.6mm~2mm, and the minimum spacing between the connector grounding micro-bumps and the edge of the mounting cavity is 0.3mm.
7. The microwave surface mount device test fixture according to claim 1, characterized in that: The micro-bump test fixture body is made of H62 material and the surface is passivated or gold-plated.