Silicon micro accelerometer head chip test fixture and test method

Abstract

This invention pertains to testing technology and relates to a testing fixture and method for mounting and electrode connection of differential capacitive silicon micro accelerometer head chips. The testing fixture consists of a chip clamping stationary block, a chip clamping moving block, an adjusting moving block, and an adjusting stationary block. A spring is fitted on a slide rail between the clamping moving block and the adjusting moving block. The chip clamping stationary block and the chip clamping moving block have matching grooves and protrusions in opposite directions, and spring probes corresponding to the chip electrode positions are installed on their corresponding surfaces. During testing, the spring extension is adjusted by an adjusting screw on the fixture to provide appropriate force to clamp the chip between the clamping stationary block and the clamping moving block, simultaneously completing the electrode connection of the head chip. Then, after inputting relevant test parameters into the program control interface of this testing method, the head chip can be tested and analyzed. This invention can improve the efficiency of electrode lead connection, positioning, testing, and analysis of the head chip by 8 to 10 times compared to existing testing methods.

Description

Technical Field

[0001] This invention pertains to testing technology and relates to a test fixture and testing method for mounting and electrode connection of differential capacitive silicon micro accelerometer head chips. Background Technology

[0002] With the continuous development of Micro-Electro-Mechanical Systems (MEMS) technology, silicon micro accelerometers have shown great advantages in the field of inertial devices due to their small size, light weight, low cost, and mass production capabilities. However, their small size and large number also bring difficulties and challenges to the testing and analysis of the meter head chip. Current testing of silicon micro accelerometer meter head chips mainly relies on equipment such as probe stations and gold wire ball bonding machines to first connect the electrodes, and then manually test and analyze key points. While this can determine the general structure of the meter head chip, it cannot accurately measure key indicators such as the free movement, dynamic characteristics, time stability, and repeatability of the meter head chip's detection mass block throughout its entire measurement range. This is mainly because connecting electrodes on different planes of the chip using a probe station cannot be aligned using a microscope, making the operation complex; and the poor positioning accuracy during chip installation is not conducive to repeatability testing. Furthermore, using equipment such as gold wire ball bonding machines to bring out the chip electrodes inevitably introduces additional and stray capacitance. Furthermore, because the aforementioned devices did not strictly adhere to the requirements for micro-capacitance testing in terms of signal connection and shielding, they could not achieve optimal testing accuracy and stability. In addition, manual testing methods not only cannot perform complete performance testing on the meter chip, but also involve a huge workload for testing and analysis. These factors have become bottlenecks for the mass production and further performance improvement of increasingly mature silicon micro-accelerometer meter chips. Summary of the Invention

[0003] The purpose of this invention is to provide a silicon micro accelerometer head chip test fixture and test method that has high testing accuracy, good stability and simple operation.

[0004] The technical solution of this invention is that the fixture is a hexahedral structure with a square through slot in the middle of its upper surface. A chip clamping fixed block, a chip clamping moving block, an adjusting moving block, and an adjusting fixed block are sequentially embedded in the through slot. The chip clamping fixed block and the adjusting fixed block are respectively fixed on both sides of the through slot. Two slide rails pass parallel through the chip clamping moving block and the adjusting moving block and are fixed between the chip clamping fixed block and the adjusting fixed block. The adjusting moving block and the adjusting fixed block are connected by an adjusting screw. A spring is sleeved on the slide rail between the clamping moving block and the adjusting block. The chip clamping fixed block and the chip clamping moving block have matching grooves and bosses in opposite directions, and spring probes corresponding to the positions of the chip electrodes are installed in their corresponding surfaces. A test signal line fixing groove for connecting with the spring probe is opened on the upper surface of the hexahedral fixture near the tail of the spring probe.

[0005] The testing method involves placing the meter chip between the chip clamping stationary block and the spring probe of the chip clamping moving block in the test fixture to complete the chip clamping and positioning and electrode connection, so that the meter chip is in the "0g" state. Then, the test program of this test method completes the testing and analysis of the meter chip.

[0006] The computer-controlled testing process is as follows:

[0007] (1) Starting from “0V”, the DC bias voltage is gradually increased from the voltage source meter to the floating electrode of the meter chip, while the capacitance value, quality factor and voltage and current value of the DC bias circuit of the meter chip under test are detected and recorded.

[0008] (2) Determine whether the detection capacitance value is within the capacitance value range of the meter chip flexible rib in the broken state. If yes, the meter chip flexible rib is determined to be broken and the test ends; otherwise, continue the test.

[0009] (3) Determine whether the quality factor value of the test exceeds the required range. If yes, the quality of the capacitor of the meter chip under test is poor and the test ends; otherwise, continue the test.

[0010] (4) Determine whether the current value of the DC bias circuit is greater than the current value when short-circuited. If yes, the meter chip is short-circuited and the test ends; otherwise, continue the test.

[0011] (5) When the measured capacitance value remains unchanged as the bias voltage increases, the DC bias voltage value is gradually reduced until “0V” is reached.

[0012] (6) Compare the capacitance value when the DC bias voltage drops to "0V" with the capacitance value when the capacitance value remains unchanged as the bias voltage increases. If the difference between the two values ​​is less than the specified value, it is determined that the detection mass block is stuck to the suspended electrode and the test ends; if the difference between the two values ​​is greater than the specified value, continue the test.

[0013] (7) Starting from “0V”, the DC bias voltage is gradually increased from the voltage source meter to the fixed electrode of the capacitor being measured on the meter chip. At the same time, the capacitance value, quality factor and voltage and current values ​​of the DC bias circuit of the meter being measured are detected and recorded.

[0014] (8) Repeat the detection steps (2) to (6);

[0015] (9) Starting from “0V”, gradually increase the DC bias voltage to the floating electrode until the highest withstand voltage value required by the meter chip. During this process, determine whether the current value of the DC bias circuit is greater than the current value when short-circuited according to step (4). If yes, it is determined that the withstand voltage performance of the meter chip is poor. If no, the DC bias voltage value is directly reduced to “0V”. According to step (6), determine whether the detection mass block and the floating electrode are stuck together. Change the electrode position of the meter chip and continue testing.

[0016] (10) After changing the position of the meter chip, perform the same test on the differential capacitor of the meter chip again according to the test content of steps (1) to (9), and the test ends.

[0017] Advantages and beneficial effects of this invention

[0018] The main advantages of using this testing device and method are as follows:

[0019] 1. While solving the problems of chip clamping and positioning and electrode connection, the accuracy, stability and repeatability of the test data are guaranteed.

[0020] 2. This invention solves the problem that existing manual testing methods for silicon micro-accelerator meter chips cannot continuously and point-by-point test the position information of the meter chip detection mass block, capacitance quality factor, capacitance leakage resistance, loop current, and the integrity and continuity of the test curve. At the same time, the test results provide the zero-point compensation voltage when the meter chip and circuit are connected for joint testing.

[0021] 3. It solves the problems that existing testing methods cannot accurately judge the performance of meter head chips, are not conducive to obtaining sufficient information during the development stage to conduct more in-depth analysis and research on various types of meter head chips, and cannot promptly propose optimization and improvement schemes for the next round of meter head chip manufacturing based on the analysis results.

[0022] 4. This method solves the problems of excessive workload and low testing efficiency caused by the clamping, positioning, electrode connection, testing, and analysis of the meter chip, which are crucial for assembly, testing, and analysis personnel. By increasing the amount of test information, the efficiency of the entire assembly, testing, and analysis process can be improved by 8 to 10 times compared to existing testing methods. Attached Figure Description

[0023] Figure 1This is a schematic diagram of the structure of the test fixture of the present invention;

[0024] Figure 2 This is a schematic diagram of the chip clamping block structure of the present invention;

[0025] Figure 3 This is a flowchart of the testing process for this invention. Detailed Implementation

[0026] The fixture is a hexahedral structure (its base 1), with a square through slot 2 in the middle of its upper surface. The chip clamping fixed block 3, the chip clamping movable block 4, the adjusting movable block 5, and the adjusting fixed block 6 are sequentially embedded in the through slot. The chip clamping fixed block and the adjusting fixed block are fixed on both sides of the through slot. Two slide rails 7 pass parallel through the chip clamping movable block and the adjusting movable block and are fixed between the chip clamping fixed block and the adjusting fixed block. The adjusting movable block and the adjusting fixed block are connected by an adjusting screw 8. A spring 9 is fitted on the slide rail between the clamping movable block and the adjusting block. The chip clamping fixed block and the chip clamping movable block have matching grooves and bosses in opposite directions, and spring probes 11 corresponding to the positions of the chip electrodes are installed in their corresponding surfaces. The spring probes can extend and retract freely in the surface. At the tail of the spring probe, a test signal line fixing groove 10 for connecting the spring probe is opened on the upper surface of the hexahedral fixture.

[0027] The testing method for silicon micro accelerometer head chip using a test fixture is as follows: First, correctly connect the test fixture, capacitance meter, voltage source meter, and relevant test signal lines, data lines, shielding wires, and grounding wires of the computer. Then, adjust the adjusting screw on the test fixture to push the adjusting block to compress the spring, ensuring sufficient elasticity to reliably clamp the head chip between the chip clamping stationary block and the chip clamping moving block. At this point, pull the chip clamping moving block away from the chip clamping stationary block. When there is sufficient space between the groove and the spring probe of the boss to place the head chip, gently place the head chip between the two probes using tweezers. After releasing the chip clamping moving block, the clamping and positioning of the head chip and electrode connection are completed. Finally, input the relevant test parameters into the program control interface of this test method to complete the testing and analysis of the head chip. The program-controlled test flow is as follows:

[0028] (1) Starting from “0V”, the DC bias voltage is gradually increased from the voltage source meter to the floating electrode of the meter head chip. At the same time, the capacitance value, quality factor and voltage and current values ​​of the DC bias circuit of the meter head under test are detected and recorded. As the DC bias voltage increases, the capacitance value under test gradually decreases. The meter head status is detected in real time by detecting parameters such as the meter head quality factor and circuit current value.

[0029] (2) Determine whether the detection capacitance value is within the capacitance value range of the meter chip flexible rib in the broken state. If yes, determine that the meter chip flexible rib is broken and the test ends; otherwise, continue testing 13.

[0030] (3) Determine whether the quality factor value of the test exceeds the required range. If yes, the quality of the capacitor of the meter chip under test is poor and the test ends; otherwise, continue testing 14.

[0031] (4) Determine whether the current value of the DC bias circuit is greater than the current value when short-circuited. If yes, determine that the meter chip is short-circuited and the test ends; otherwise, continue testing for 15.

[0032] (5) When the measured capacitance value remains unchanged as the bias voltage increases, the DC bias voltage value is gradually reduced until “0V” is reached.

[0033] (6) Compare the capacitance value when the DC bias voltage drops to "0V" with the capacitance value when the capacitance value remains unchanged as the bias voltage increases. If the difference between the two values ​​is less than the specified value, it is determined that the detection mass block is stuck to the suspended electrode and the test ends; if the difference between the two values ​​is greater than the specified value, continue the test 17.

[0034] (7) Starting from “0V”, the DC bias voltage is gradually increased from the voltage source meter to the fixed electrode of the capacitor being tested on the meter chip. At the same time, the capacitance value, quality factor and voltage and current values ​​of the DC bias circuit of the meter being tested are detected and recorded.

[0035] (8) Repeat the detection steps (2) to (6);

[0036] (9) Starting from “0V”, gradually increase the DC bias voltage to the floating electrode until the highest withstand voltage value required by the meter chip. During this process, determine whether the current value of the DC bias circuit is greater than the current value when short-circuited according to step (4). If yes, it is determined that the withstand voltage performance of the meter chip is poor. If no, the DC bias voltage value is directly reduced to “0V”. According to step (6), determine whether the detection mass block and the floating electrode are stuck together. Change the electrode position of the meter chip and continue testing 19.

[0037] (10) After changing the position of the meter chip, perform the same test on the differential capacitor of the meter chip again according to the test content of steps (1) to (9), and the test ends 20.

[0038] Example

[0039] To test a meter chip with a base capacitance of 30.00 pF, after completing all connection preparations, input the chip's batch number (e.g., "t2009060"), location number "x35", ambient temperature "23℃", and ambient humidity "60RH%" into the program interface. The program then controls the application of a gradually increasing DC bias voltage to the floating electrode of the meter chip until the measured capacitance no longer decreases with increasing bias voltage (e.g., the capacitance value is 24.00 pF at this point). If any faults such as "broken pins," "poor quality factor," or "short circuit" are found during this process, the test is stopped, and the meter chip is classified as a corresponding failed meter chip. If the test is normal, the DC bias voltage is gradually reduced to zero volts, and the measured capacitance value at this point is compared with "24.00 pF". If they are the same, it is determined that the central silicon plate of the meter chip is stuck to the fixed electrode; otherwise, it should be restored to the initial value of "30.00 pF". Then, a bias voltage is applied to the fixed electrode of the capacitor being tested on the meter chip in the same way, and the above tests and analyses are completed. After passing the above tests, the meter chip is subjected to progressively increasing withstand voltage tests until the required maximum withstand voltage value is reached. During the test, the meter chip and its position are changed in a timely manner according to the prompts on the program interface. The test program automatically analyzes the test data and provides the test results for each meter chip.

Claims

1. A test fixture for silicon micro accelerometer head chip, characterized in that, The fixture has a hexahedral structure with a square through slot in the middle of its upper surface. The chip clamping fixed block, chip clamping moving block, adjusting moving block, and adjusting fixed block are sequentially embedded in the through slot. The chip clamping fixed block and adjusting fixed block are fixed on both sides of the through slot. Two slide rails pass parallel through the chip clamping moving block and adjusting moving block and are fixed between the chip clamping fixed block and adjusting fixed block. The adjusting moving block and adjusting fixed block are connected by adjusting screws. A spring is fitted on the slide rail between the chip clamping moving block and adjusting block. The chip clamping fixed block and chip clamping moving block have matching grooves and bosses in opposite directions, and spring probes corresponding to the positions of the chip electrodes are installed in their corresponding surfaces. Test signal line fixing slots for connecting with the spring probes are opened on the upper surface of the hexahedral fixture and near the tail of the spring probe.

2. A test method for testing a silicon micro accelerometer head chip using the test fixture described in claim 1, characterized in that, The meter chip is placed between the chip holding stationary block and the spring probe of the chip holding movable block in the test fixture to complete the chip clamping and positioning and electrode connection, bringing the meter chip to the "0g" state. Then, the test program of this test method completes the testing and analysis of the meter chip. The program-controlled testing process is as follows: (1) Starting from "0V", the DC bias voltage is gradually increased from the voltage source meter to the floating electrode of the meter chip. At the same time, the capacitance value, quality factor and voltage and current values ​​of the DC bias circuit of the meter chip under test are detected and recorded. (2) Determine whether the detection capacitance value is within the capacitance value range of the meter chip flexible rib in the broken state. If yes, the meter chip flexible rib is determined to be broken and the test ends; otherwise, continue the test. (3) Determine whether the quality factor value of the test exceeds the required range. If yes, the quality of the capacitor of the meter chip under test is poor and the test ends; otherwise, continue the test. (4) Determine whether the current value of the DC bias circuit is greater than the current value when short-circuited. If yes, the meter chip is short-circuited and the test ends; otherwise, continue the test. (5) When the measured capacitance value remains unchanged as the bias voltage increases, the DC bias voltage value is gradually reduced until "0V" is reached. (6) Compare the capacitance value when the DC bias voltage drops to "0V" with the capacitance value when the capacitance value remains unchanged as the bias voltage increases. If the difference between the two values ​​is less than the specified value, it is determined that the detection mass block is stuck to the suspended electrode and the test ends; if the difference between the two values ​​is greater than the specified value, continue the test. (7) Starting from "0V", the DC bias voltage is gradually increased from the voltage source meter to the fixed electrode of the capacitor being measured on the meter chip. At the same time, the capacitance value, quality factor and voltage and current values ​​of the DC bias circuit of the meter being measured are detected and recorded. (8) Repeat the detection steps (2) to (6); (9) Starting from "0V", gradually increase the DC bias voltage to the floating electrode until the highest withstand voltage value required by the meter chip. During this process, determine whether the current value of the DC bias circuit is greater than the current value when short-circuited according to step (4). If yes, it is determined that the withstand voltage performance of the meter chip is poor. If no, the DC bias voltage value is directly reduced to "0V". According to step (6), determine whether the detection mass block and the floating electrode are stuck together. Change the electrode position of the meter chip and continue the test. (10) After changing the position of the meter chip, perform the same test on the differential capacitor of the meter chip again according to the test content of steps (1) to (9), and the test ends.

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