Low-cost and compact surface acoustic wave temperature sensor test system and test method

Abstract

The present invention discloses a low-cost, compact surface acoustic wave (SAW) temperature sensor testing system and method, relating to the field of SAW temperature sensor testing. The system comprises a sensor testing device, a network analyzer, and a PC terminal, wherein the sensor testing device is connected to the network analyzer, which in turn is connected to the PC terminal. The sensor testing device comprises a test board, a sensor crimping device, and a fixed base. The test board comprises a sensor positioning plate, a vertical conductive film, an electrical connection plate, and a radio frequency connector. The vertical conductive film is sandwiched between the sensor positioning plate and the electrical connection plate, which is connected to the radio frequency connector. The test board is mounted on the fixed base via a fixing assembly. The sensor crimping device is used to secure the sensor to be tested during testing. The device of the present invention has a simple and durable structure, a simple testing method, and can be used to perform batch testing of SAW temperature sensors, thereby reducing the testing cost of SAW temperature sensor chips.

Description

Technical Field

[0001] The present invention relates to the field of surface acoustic wave temperature sensor testing, and in particular to a low-cost and compact surface acoustic wave temperature sensor testing system and testing method. Background Art

[0002] With the continuous advancement of technology, surface acoustic wave temperature sensors are widely used in various industries. To ensure the reliability and stability of surface acoustic wave temperature sensors, they need to be comprehensively tested. Surface acoustic wave temperature sensors require many test parameters, such as resonant frequency, resonant Q value, out-of-band suppression, parasitic peaks, etc. After the temperature sensor is packaged, it needs to be tested one by one for each parameter. The performance testing of surface acoustic wave temperature sensors is a chip-level test. Not only is the number of products to be tested huge, but the test must also be non-destructive. After the test is completed, the appearance of the sensor cannot be changed, especially the sensor pins cannot be tinned, otherwise the sensor will not be able to be sold normally.

[0003] For batch testing of surface acoustic wave temperature sensors, the current conventional practice is to use an RF probe station for electrical connection (the RF probe is pressed onto the pins of the sensor to be tested, and the RF probe is used instead of the test cable to achieve electrical connection) and a network analyzer as the test equipment. The two form a test system for testing.

[0004] RF probe stations are expensive, typically costing hundreds of thousands to millions of yuan. Furthermore, these delicate systems require specialized user training and are expensive to maintain. They are also bulky and require specialized brackets and storage in dedicated rooms, occupying a large area and making them difficult to move. RF probe stations are typically limited in number, making them a frequent problem for large-scale sensor testing, as well as insufficient testing personnel.

[0005] Therefore, technicians in this field are committed to developing a low-cost and flexible surface acoustic wave temperature sensor testing system and testing method to achieve batch testing of surface acoustic wave temperature sensors with extremely low price cost, simple operation method, and small space occupation method, thereby reducing the testing cost of surface acoustic wave temperature sensor chips. Summary of the Invention

[0006] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is how to solve the current situation of relying on expensive RF probe stations for testing: the RF probe station realizes the electrical connection of RF through probes, which is expensive to manufacture and has high procurement costs; the RF probe station equipment is sophisticated and complex, and is easily damaged, requiring personnel with relevant professional knowledge to be trained and on the job, and to be operated by dedicated personnel; the RF probe station is large and bulky, occupies a large office space, and has high usage costs.

[0007] To achieve the above object, the present invention provides a low-cost, compact surface acoustic wave temperature sensor testing system, comprising a sensor testing device, a network analyzer for storing calibration files and parameter measurements, and a PC terminal, wherein the sensor testing device is connected to the network analyzer, and the network analyzer is connected to the PC terminal;

[0008] The sensor testing device includes a test board, a sensor crimping device and a fixed base. The test board includes a sensor positioning plate, a vertical conductive film, an electrical connection plate and a radio frequency connector. The vertical conductive film is clamped between the sensor positioning plate and the electrical connection plate. The electrical connection plate and the radio frequency connector are connected. The test board is installed on the fixed base through a fixing component. The sensor crimping device is used to fix the sensor to be tested during testing.

[0009] Furthermore, there are 4 positioning plate positioning and fixing holes around the sensor positioning plate, and 4 electrical connection plate positioning and fixing holes around the electrical connection plate. The positions of the 4 positioning plate positioning and fixing holes correspond to the positions of the 4 electrical connection plate positioning and fixing holes on the lower electrical connection plate.

[0010] Furthermore, there is a square sensor positioning hole in the middle of the sensor positioning plate. The length and width of the sensor positioning hole are larger than the length and width of the sensor to be tested, ensuring that the sensor to be tested can be placed in the positioning hole normally. At the same time, the free movement space of the sensor to be tested in the sensor positioning hole is smaller than the spacing of the bottom pads of the sensor to be tested.

[0011] Furthermore, the sensor positioning board is implemented with a single-sided board.

[0012] Furthermore, notches are left on both sides of the sensor positioning plate, and the width of the notches is greater than the width of the RF connector, so that the electrical connection plate can be normally docked with the sensor positioning plate after the RF connector is welded.

[0013] Furthermore, the electrical connection board is a double-sided board.

[0014] Furthermore, an electrical connection pad of the sensor to be tested is provided in the middle of the electrical connection board, and the position of the electrical connection pad of the sensor to be tested corresponds to the position of the sensor to be tested on the sensor positioning board.

[0015] Furthermore, the sensor crimping device includes a handle and a crimping rod. The crimping head of the crimping rod is covered with a rubber pad. The crimping rod is fixed to the front end of the sensor crimping device by a lock. The installation position is determined by the length of the crimping rod, so that after pressing down, the sensor to be tested is located in the center position of the rubber pad of the sensor crimping device.

[0016] Furthermore, the electrical connection board draws corresponding pads at the input and output pins of the chip to be tested, and the pads are connected to the radio frequency connector through an extended microstrip line.

[0017] The present invention also provides a low-cost and flexible surface acoustic wave temperature sensor testing method, which comprises the following steps:

[0018] Step 1. Calibrate the sensor test device;

[0019] Step 2. Save the calibration file to the network analyzer;

[0020] Step 3. Input the current ambient temperature and the classification code of the sensor to be tested on the PC terminal;

[0021] Step 4. Determine the installation position of the sensor crimping device and fix it so that the sensor to be tested is located at the center of the rubber pad of the sensor crimping device after pressing down;

[0022] Step 5. Place the sensor to be tested into the test positioning hole and press down the handle to make the sensor to be tested electrically connected to the electrical connection pad of the sensor to be tested through the vertical conductive film;

[0023] Step 6. On the PC terminal, use the test software to automatically test and save the test results;

[0024] Step 7. The test software gives a conclusion on whether the sensor to be tested is qualified according to the qualification criteria;

[0025] Step 8. Test the batch of sensors in turn and calculate the qualified rate of the surface acoustic wave temperature sensors in the batch.

[0026] Compared with the existing technical solutions, the beneficial effects brought by the solution of the present invention are:

[0027] Compared with conventional probe stations, this test system has the following advantages

[0028] 1. Utilizing the vertical conductive properties of the vertical conductive film, a combination of low-cost vertical conductive film, PCB traces, and RF cables is used to achieve electrical connection between the surface acoustic wave temperature sensor and the test instrument, replacing the mechanical electrical connection of the RF probe station. The electrical connection function of the RF probe station during sensor testing is achieved at a low cost. This solves the problem of overly expensive test fixtures. Procurement costs are significantly reduced from hundreds of thousands to millions to just a few hundred yuan.

[0029] 2. The sensor crimping device has a simple structure, is durable, and is easy to operate. Operators do not need to master complex professional knowledge and can take up the job after simple training. There is no requirement for professional background for testers. It solves the problem of insufficient number of expensive instruments and insufficient testing personnel during large-scale testing.

[0030] 3. The test fixture is small in size and light in weight, and does not require a dedicated fixed bracket, solving the problem of the test fixture occupying too much office space;

[0031] 4. The present invention adopts a sandwich structure, sandwiching the vertical conductive film between two printed circuit boards. A hole is punched in the middle of the printed circuit board according to the shape of the sensor to achieve the positioning of the sensor to be tested. The electrical connection at the bottom is also achieved with a low-cost PCB board;

[0032] 5. The sensor crimping device of the present invention fixes the crimping rod through a simple lock, and covers the crimping head of the crimping rod with a rubber pad, which ensures the crimping strength without damaging the sensor. At the same time, the rubber pad has a high temperature coefficient, which avoids the test deviation caused by the temperature change of the hand when crimping the sensor by hand.

[0033] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic structural diagram of a test board according to a preferred embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the test board after assembly according to a preferred embodiment of the present invention;

[0036] Figure 3 It is a structural schematic diagram of a sensor testing device according to a preferred embodiment of the present invention;

[0037] Figure 4 1 is a schematic structural diagram of a sensor testing system according to a preferred embodiment of the present invention;

[0038] Among them: 1- surface acoustic wave temperature sensor to be tested, 2- sensor positioning plate, 21- test positioning hole, 22- positioning and fixing hole of positioning plate, 23- notch of sensor positioning plate, 3- vertical conductive film, 4- RF connector, 5- electrical connection plate, 51- electrical connection pad of sensor to be tested, 52- positioning and fixing hole of electrical connection plate, 6- sensor crimping device, 61- handle, 62- rubber pad, 7- pad, 8- stud, 9- fixed base. DETAILED DESCRIPTION

[0039] The following describes several preferred embodiments of the present invention with reference to the accompanying drawings to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0040] In the drawings, components with identical structures are denoted by the same reference numerals, and components with similar structures or functions are denoted by similar reference numerals. The size and thickness of each component shown in the drawings are arbitrary and are not limited by the present invention. For clarity, the thickness of components in some places in the drawings is appropriately exaggerated.

[0041] like Figure 1 As shown, the test board structure of a preferred embodiment of the present invention includes: a surface acoustic wave temperature sensor 1 to be tested, a sensor positioning plate 2, a vertical conductive film 3, an electrical connection plate 5, and a radio frequency connector 4. The sensor positioning plate 2 is implemented using a single-sided board, and the board material is preferably inexpensive FR4. There are four positioning plate positioning and fixing holes 22 around the sensor positioning plate 2. The positions of these four positioning plate positioning and fixing holes 22 completely overlap with the positions of the four electrical connection plate positioning and fixing holes 52 on the electrical connection plate 5 below. The positioning plate positioning and fixing holes 22 serve two functions: first, to fix the sensor positioning plate 2, and second, to position it with the electrical connection plate 5 below, ensuring that the pins of the surface acoustic wave temperature sensor 1 to be tested overlap with the corresponding PCB pads on the electrical connection plate 5. A test positioning hole 21 is located in the center of the sensor positioning plate 2. The size of the test positioning hole 21 is determined by the size of the SAW temperature sensor 1 to be tested. The length and width of the test positioning hole 21 are slightly larger than the SAW temperature sensor 1 to be tested, ensuring that the SAW temperature sensor 1 to be tested can be properly inserted into the test positioning hole 21. At the same time, the free movement space of the SAW temperature sensor 1 to be tested within the test positioning hole 21 is no greater than the spacing between the bottom solder pads of the SAW temperature sensor 1 to be tested. Generally speaking, the length and width of the test positioning hole 21 are 0.2 mm larger than the length and width of the SAW temperature sensor 1 to be tested. The thickness of the sensor positioning plate 2 is slightly less than the thickness of the SAW temperature sensor 1 to be tested, ensuring that the SAW temperature sensor 1 to be tested is higher than the sensor positioning plate 2 and can be contacted by the bottom of the sensor crimping device 6 without being interfered with by the sensor positioning plate 2. Generally speaking, the thickness of the SAW temperature sensor 1 to be tested is approximately 0.5 mm greater than the thickness of the sensor positioning plate 2. Sensor positioning plate notches 23 are provided on both sides of the sensor positioning plate 2. These notches are slightly wider than the RF connector 4 to facilitate proper docking of the electrical connection plate 5 with the sensor positioning plate 2 after soldering the RF connector 4. Generally, the width of the sensor positioning plate notches 23 is 2 mm greater than the width of the RF connector 4. The electrical connection plate 5 is a double-sided board, preferably made of inexpensive FR4 with a thickness of 1.6 mm.

[0042] There are four electrical connection board positioning and fixing holes 52 around the electrical connection board 5, and the positions of the electrical connection board positioning and fixing holes 52 completely coincide with the positions of the positioning board positioning and fixing holes 22. In the middle of the electrical connection board 5, there is an electrical connection pad for the surface acoustic wave temperature sensor 1 to be tested, and the position of the pad corresponds one-to-one to the position of the surface acoustic wave temperature sensor 1 to be tested on the sensor positioning board 2. The above-mentioned electrical connection pads must not be solder-blocked to ensure that the pins of the surface acoustic wave temperature sensor 1 to be tested can be electrically connected to the corresponding pins through the vertical conductive film 3. On the electrical connection board 5, corresponding pads are drawn at the input and output pins of the chip to be tested, and connected to the RF connector 4 through an extended microstrip line. The extended microstrip line adopts a 50 ohm impedance gradient line design to ensure the impedance continuity of the semi-automatic test system. The RF connector 4 is welded on the electrical connection board 5 and is used to connect the surface acoustic wave temperature sensor 1 to be tested and the network analyzer. The RF connector 4 is preferably a socket type SMA-KHD.

[0043] like Figure 2 As shown, the vertical conductive film 3 is sandwiched between the sensor positioning plate 2 and the electrical connection plate 5, establishing an electrical connection between the electrical pins of the SAW temperature sensor 1 to be tested and the electrical connection pads 51 of the sensor to be tested on the electrical connection plate 5. The vertical conductive film 3 only needs to be slightly larger than the pad area of ​​the SAW temperature sensor 1 to be tested. In a preferred embodiment of the present invention, the SAW temperature sensor 1 to be tested has a body area of ​​5 mm x 5 mm, while the vertical conductive film 3 has an area of ​​9 mm x 9 mm. The vertical conductive film 3 enables vertical electrical connection. During testing, electrical performance testing can be achieved by simply pressing the SAW temperature sensor 1 to be tested against the vertical conductive film 3, without the need for soldering, achieving efficient and simple sensor testing.

[0044] Table 1 shows the advantages of this test system compared with conventional probe stations:

[0045] Table 1 Comparison between this test system and conventional probe stations

[0046]

[0047] The present invention can realize the electrical connection function of the radio frequency probe station during the sensor testing process at a low cost, solving the problem of overly expensive test fixtures. The procurement cost is significantly reduced from hundreds of thousands to millions to just a few hundred yuan. See Table 2 for details:

[0048] Table 2. Bill of Materials Cost of a Low-Cost, Flexible SAW Temperature Sensor Test System

[0049]

[0050] like Figure 3As shown, the sensor crimping device 6 is used to fix the surface acoustic wave temperature sensor 1 to be tested during testing. The crimping rod of the sensor crimping device 6 is covered with a rubber pad 62 to ensure that no damage is caused when the surface acoustic wave temperature sensor 1 to be tested is pressed. The installation position of the sensor crimping device 6 is determined by the length of the crimping rod to ensure that the surface acoustic wave temperature sensor 1 to be tested is located in the center of the insulating rubber of the crimping device after pressing down. The sensor crimping device 6 is first installed on the pad 7, and the height of the pad 7 is the same as the height of the stud 8 to ensure that the lifting and pressing actions of the sensor crimping device 6 will not interfere with other components. The height of the stud 8 is generally selected to be 12mm; the handle 61 is used to operate the lifting or pressing of the crimping device; the rubber pad 62 is used to press the surface acoustic wave temperature sensor 1 to be tested when pressing down, and the fixed base 9 is used to fix the sensor positioning plate 2, the vertical conductive film 3 and the electrical connection plate 5. The fixed base 9 is made of metal, either aluminum or iron. The sensor positioning plate 2, vertical conductive film 3, electrical connection plate 5, and RF connector 4 are first secured to the fixed base 9 using studs 8 and screws. The rubber pads, which can be made of silicone, rubber, or plastic, ensure crimping strength without damaging the sensor under test. Furthermore, the high temperature coefficient of the rubber pads prevents test deviations caused by hand temperature fluctuations when crimping the sensor.

[0051] In the present invention, the RF connector 4 is preferably of the SMA series to achieve electrical connection. Other types of electrical connection methods, such as MCX, IPEX, etc., can be used. This is just a simple replacement of the connection method and does not affect the essence of the present invention.

[0052] In the present invention, the electrical connection board 5 is made of FR4 board, but other boards can also be used to achieve the same function. This simple change does not affect the essence of the present invention.

[0053] like Figure 4 The figure shows a low-cost, compact SAW temperature sensor testing system according to a preferred embodiment of the present invention. It includes a sensor testing device, a network analyzer for storing calibration files and parameter measurements, and a PC terminal. The sensor testing device is connected to the network analyzer via an RF cable, and the network analyzer is connected to the PC terminal via an Ethernet cable. The present invention's low-cost, compact SAW temperature sensor testing method includes the following steps:

[0054] Step 1. Calibrate the sensor test device;

[0055] Step 2. Save the calibration file to the network analyzer;

[0056] Step 3. Input the current ambient temperature and the classification code of the sensor to be tested on the PC terminal;

[0057] Step 4. Determine the installation position of the sensor crimping device and fix it so that the sensor to be tested is located at the center of the rubber pad of the sensor crimping device after pressing down;

[0058] Step 5. Place the sensor to be tested into the test positioning hole and press down the handle to make the sensor to be tested electrically connected to the electrical connection pad of the sensor to be tested through the vertical conductive film;

[0059] Step 6. On the PC terminal, use the test software to automatically test and save the test results;

[0060] Step 7. The test software gives a conclusion on whether the sensor to be tested is qualified according to the qualification criteria;

[0061] Step 8. Test the batch of sensors in turn and calculate the qualified rate of the surface acoustic wave temperature sensors in the batch.

[0062] The preferred embodiments of the present invention have been described in detail above. It should be understood that numerous modifications and variations based on the concepts of the present invention are possible without inventive effort by those skilled in the art. Therefore, any technical solution that can be derived by one skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A low-cost, compact surface acoustic wave temperature sensor test system, characterized by: It includes a sensor test device, a network analyzer and a PC terminal for storing calibration files and parameter measurements, wherein the sensor test device is connected to the network analyzer, and the network analyzer is connected to the PC terminal; The sensor testing device includes a test plate, a sensor crimping device and a fixed base, the test plate includes a sensor positioning plate, a vertical conductive film, an electrical connection plate, and a radio frequency connector; the vertical conductive film is clamped between the sensor positioning plate and the electrical connection plate, the electrical connection plate and the radio frequency connector are connected, and the test plate is installed on the fixed base through a fixing component; the sensor crimping device is used to fix the sensor to be tested during testing; there are 4 positioning plate positioning fixing holes around the sensor positioning plate, and there are 4 electrical connection plate positioning fixing holes around the electrical connection plate, and the 4 positioning plate positioning holes The position of the fixing hole corresponds to the position of the four electrical connection plate positioning fixing holes on the electrical connection plate below; there is a square sensor positioning hole in the middle of the sensor positioning plate, the length and width of the sensor positioning hole are larger than the length and width of the sensor to be tested, ensuring that the sensor to be tested can be normally placed in the positioning hole. At the same time, the free movement space of the sensor to be tested in the sensor positioning hole is smaller than the spacing between the bottom pads of the sensor to be tested; there are notches on both sides of the sensor positioning plate, the width of the notch is larger than the width of the RF connector, so that the electrical connection plate can be normally docked with the sensor positioning plate after the RF connector is welded; The sensor crimping device includes a handle and a crimping rod. The crimping head of the crimping rod is covered with a rubber pad. The crimping rod is fixed to the front end of the sensor crimping device by a lock. The installation position is determined by the length of the crimping rod, so that after pressing down, the sensor to be tested is located in the center position of the rubber pad of the sensor crimping device.

2. The low-cost, compact surface acoustic wave temperature sensor testing system according to claim 1, wherein: The sensor positioning board is implemented with a single-sided board.

3. The low-cost, compact surface acoustic wave temperature sensor testing system according to claim 1, wherein: The electrical connection board is a double-sided board.

4. The low-cost, compact surface acoustic wave temperature sensor testing system according to claim 1, wherein: An electrical connection pad for the sensor to be tested is provided in the middle of the electrical connection plate, and a position of the electrical connection pad for the sensor to be tested corresponds to a position of the sensor to be tested on the sensor positioning plate.

5. The low-cost, compact surface acoustic wave temperature sensor testing system according to claim 1, wherein: The electrical connection board has corresponding pads drawn at the input and output pins of the chip to be tested, and the pads are connected to the radio frequency connector through an extended microstrip line.

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