Radio frequency breakdown voltage testing method for high-Q multilayer ceramic dielectric capacitor

Abstract

The invention discloses a radio frequency breakdown voltage testing method for a high-Q multilayer ceramic dielectric capacitor, and belongs to the technical field of electronic component testing. The method comprises the following steps: connecting a capacitor to be tested and an inductor in series to construct a resonant circuit; the resonant frequency and the quality factor of the circuit are accurately measured by using equipment such as a vector network analyzer; applying the radio frequency power of the resonant frequency to the circuit and gradually increasing the power level, judging whether the capacitor has radio frequency breakdown or not by means of monitoring sudden change of power parameters of the circuit or optical observation and the like, and recording the radio frequency power level; and finally, based on the radio frequency power level, the quality factor, the resonant frequency and the capacitance value of the to-be-measured capacitor, calculating to obtain the radio frequency breakdown voltage of the to-be-measured capacitor. The invention solves the problem that the radio frequency working condition cannot be accurately simulated in the prior art, and has the advantages of real test environment, accurate and reliable result and simplicity and convenience in operation.

Description

Technical Field

[0001] This invention relates to the field of electronic component testing technology, and specifically to a method for testing the radio frequency breakdown voltage of a high-Q multilayer ceramic capacitor. Background Technology

[0002] High-Q (quality factor) multilayer ceramic capacitors are critical components in high-frequency circuits, such as radio frequency (RF) communication equipment, and their reliability is essential for the stable operation of the entire system. In high-power applications such as RF microwave circuits, capacitors often break down due to excessively high RF voltages, which is a major failure mode. Therefore, RF breakdown voltage is a key parameter for evaluating the withstand voltage performance of high-Q multilayer ceramic capacitors.

[0003] Currently, traditional testing methods primarily employ direct current (DC) voltage testing, which involves continuously increasing the DC voltage applied across the capacitor until it breaks down to obtain the breakdown voltage value. However, the testing environment of this method differs significantly from the actual radio frequency (RF) environment in which capacitors operate. Due to physical effects such as skin effect, dielectric loss, and parasitic parameters, which only become significant at high frequencies, DC test results often fail to accurately reflect the capacitor's withstand voltage capability under real RF operating conditions. This leads to a large deviation between the measured results and actual performance, failing to provide reliable data support for circuit design.

[0004] Therefore, there is an urgent need in this field for a simple solution that can directly and accurately test the radio frequency breakdown voltage of capacitors at actual operating frequencies. Summary of the Invention

[0005] The purpose of this invention is to provide a method for testing the radio frequency breakdown voltage of a high-Q multilayer ceramic capacitor, so as to overcome the above-mentioned shortcomings of the prior art, and to simulate the actual working conditions of the capacitor. The test results are accurate and reliable, and the operation is simple.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for testing the radio frequency breakdown voltage of a high-Q multilayer ceramic capacitor includes the following steps: S1: Circuit setup: Connect the capacitor under test and the inductor in series to form a series resonant circuit. The capacitor is a high-Q multilayer ceramic capacitor. S2: Parameter measurement to obtain the resonant frequency f and its quality factor q at the resonant frequency point of the series resonant circuit; S3: Breakdown test, apply radio frequency power at the resonant frequency f to the series resonant circuit, and increase the radio frequency power level in an incremental manner, while monitoring the state changes of the capacitor under test or the circuit until it is determined that the capacitor under test has experienced radio frequency breakdown, and record the radio frequency power level P when the breakdown occurs. S4: Voltage calculation: Based on the RF power level P, the quality factor q, the resonant frequency f, and the capacitance value c of the capacitor under test, the RF breakdown voltage V of the capacitor under test is calculated.

[0007] Furthermore, in S1: The inductor is an air-wound inductor; The circuit is constructed using a high-frequency circuit board, which employs a microstrip line or coplanar waveguide structure to achieve impedance matching.

[0008] Furthermore, in S1: The capacitance value c of the capacitor under test ranges from 0.1 pF to 10 nF; The inductance value L of the inductor is in the range of 1 nH to 1 mH.

[0009] Further, S2 includes: measuring the transmission parameters S21 of the series resonant circuit using a vector network analyzer or an impedance analyzer, obtaining the resonant frequency f by determining the center frequency of the S21 resonant curve, and calculating the quality factor q according to the formula q = f / Δf by measuring the 3dB bandwidth Δf of the resonant curve.

[0010] Furthermore, the incremental increase in RF power level described in S3 is a step-power mode, that is, applying a continuous wave RF signal and gradually increasing its power value, and maintaining it for a period of time at each power step.

[0011] Furthermore, the incremental increase in RF power level described in S3 is a pulsed power mode, that is, applying a series of RF power pulses and gradually increasing the peak power of the RF power pulses, wherein the power duty cycle of the pulses is 0.1%-20% and the peak power time is 0.1ms-10ms.

[0012] Furthermore, the state changes of the capacitor under test described in S3 are observed by optical equipment to determine whether the capacitor generates electrical sparks or suffers physical damage.

[0013] Furthermore, the state changes of the circuit described in S3 are monitored in the following manner: The output power and reflected power of the circuit are monitored, and a sudden drop in output power or a sudden increase in reflected power is used as the criterion for determining breakdown.

[0014] Furthermore, in S4, the formula for calculating the radio frequency breakdown voltage V is: ; Where P is the RF power at breakdown, q is the quality factor, f is the resonant frequency, and c is the capacitance of the capacitor under test.

[0015] Another objective of this invention is to provide a radio frequency breakdown voltage testing system for a high-Q multilayer ceramic capacitor, comprising a processor and a memory, wherein the memory stores a computer program, and when the computer program is executed by the processor, it implements the radio frequency breakdown voltage testing method for the high-Q multilayer ceramic capacitor.

[0016] The present invention provides a method for testing the radio frequency breakdown voltage of a high-Q multilayer ceramic capacitor, which, compared with the prior art, achieves the following significant advantages: Highly realistic testing environment: This invention performs tests directly at radio frequency, perfectly simulating the actual working conditions of capacitors, ensuring that the test results can truly reflect their withstand voltage performance in the application scenario, and overcoming the limitations of traditional DC testing.

[0017] High measurement accuracy: By utilizing the series resonance principle, the high-frequency high voltage that is difficult to measure directly is converted into the radio frequency power and circuit Q value that are relatively easy to measure accurately. And through rigorous mathematical formulas, the accuracy and reliability of the measurement are greatly improved.

[0018] Highly adaptable and easy to operate: This invention organically integrates resonance parameter measurement and power breakdown testing, forming a complete test scheme with clear logic, well-defined steps, and easy implementation. It has relatively conventional equipment requirements and is easy to promote and use in production and quality inspection. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0021] This embodiment provides a method for testing the radio frequency breakdown voltage of a high-Q (quality factor) multilayer ceramic capacitor, such as... Figure 1As shown, the process includes: circuit construction, connecting the capacitor under test (DUT) and an inductor in series to form a series resonant circuit, wherein the DUT is a high-Q multilayer ceramic capacitor; parameter measurement, obtaining the resonant frequency f and its quality factor q at the resonant frequency of the series resonant circuit; breakdown testing, applying radio frequency (RF) power at the resonant frequency f to the series resonant circuit and increasing the RF power level incrementally while monitoring the state changes of the DUT or the circuit until it is determined that the DUT has experienced RF breakdown, and recording the RF power level P at the time of breakdown; voltage calculation, calculating the RF breakdown voltage V of the DUT based on the RF power level P, the quality factor q, the resonant frequency f, and the capacitance value c of the DUT. The following is a detailed description with reference to an embodiment.

[0022] S1: Circuit setup: Connect the capacitor under test and the inductor in series to form a series resonant circuit. The capacitor is a high-Q multilayer ceramic capacitor.

[0023] The purpose of this step is to construct a series resonant circuit that is as pure as possible. A high-Q multilayer ceramic capacitor of capacitance c (typically ranging from 0.1 pF to 10 nF) is mounted in series on a circuit board with an air-wound inductor L, typically ranging from 1 nH to 1 mH. This circuit forms a series resonant structure.

[0024] In this embodiment, a high-Q multilayer ceramic capacitor with a nominal capacitance of c = 1nF is selected as the device under test (DUT). An air-wound inductor with an inductance of L = 138 nH is matched to it. The air-wound inductor is chosen because it has a high self-resonant frequency, a large Q value, and a small distributed capacitance, which helps to obtain clear and accurate resonant characteristics at radio frequency.

[0025] Circuit board design is critical, requiring the use of high-frequency circuit board materials (such as Rogers RO4003C) and a layout employing transmission line structures such as microstrip lines or coplanar waveguides to achieve good impedance matching (typically to 50 ohms). Component placement should be compact to minimize lead inductance and parasitic capacitance. Solder joints should be smooth and robust to avoid introducing additional impedance discontinuities. All connections should utilize phase-stable RF coaxial cables and high-quality SMA or N-type connectors.

[0026] S2: Parameter measurement to obtain the resonant frequency f and its quality factor q at the resonant frequency of the series resonant circuit. Specifically, the transmission parameter S21 of the series resonant circuit is measured using a vector network analyzer or impedance analyzer. The resonant frequency f is obtained by determining the center frequency of the S21 resonant curve. The quality factor q is calculated by measuring the 3dB bandwidth Δf of the resonant curve and applying the formula q = f / Δf.

[0027] Alternatively, the resonant frequency f (typically ranging from 300 kHz to 3 GHz) and the quality factor q (typically higher than 10) can also be measured using a conventional Q meter, where the resonant frequency f is indicated by the connected signal source and the quality factor q is read directly from the Q meter.

[0028] This embodiment uses a high-performance vector network analyzer (VNA), such as the Keysight E5071C, for measurement. The two ports of the VNA are connected to the input and output of a series resonant circuit via calibrated cables to perform two-port S-parameter measurements (typically the S21 transmission coefficient). Calibration is essential for measurement accuracy. Before measurement, a full two-port calibration must be performed on the cable ends using electronic calibration kits or mechanical calibration tools (such as SOLT: Short-Circuit-Open-Load-Straight-Through) to eliminate systematic errors introduced by the cable and connectors. The VNA is set to scan within the expected frequency range (e.g., 10MHz to 20MHz). After scanning, a clear resonant peak (corresponding to the series resonant point) will be displayed on the VNA screen. Using the VNA's marker and search max functions, the resonant frequency f = 13.56MHz can be accurately read. Subsequently, using the bandwidth measurement function of the VNA, two frequency points f1 and f2, which differ from the S21 value at the resonant point by 3dB, are found. The 3dB bandwidth Δf = f2 - f1, and the quality factor q can be automatically calculated using the formula q = f / Δf. In this embodiment, q = 100 is measured.

[0029] S3: Breakdown test, apply radio frequency power at the resonant frequency f to the series resonant circuit, and increase the radio frequency power level in an incremental manner, while monitoring the state changes of the capacitor under test or the circuit until it is determined that the capacitor under test has experienced radio frequency breakdown, and record the radio frequency power level P when the breakdown occurs.

[0030] The incremental increase in RF power level, i.e., the power application strategy, can employ either a step-type power mode or a pulsed power mode, specifically as follows: Stepped Power Mode: A continuous wave RF signal is applied and its power value is gradually increased, with each power step maintained for a period of time. Initially, the signal generator is set to output a very low power signal (e.g., -10 dBm), which, after amplification, increases the initial power injected into the circuit to a certain value (e.g., 10W). Then, the output level of the signal generator is slowly increased in small steps (e.g., 5W or 10W). Each power step is maintained for several seconds to tens of seconds to observe whether the circuit response stabilizes and to allow the capacitors time to thermally equalize.

[0031] Pulsed Power Mode: A series of RF power pulses are applied, with the peak power of the RF power pulses gradually increasing. The RF power source outputs a pulse train with a very low duty cycle and adjustable peak power. This method can significantly reduce the average power during the test, reduce the heat accumulation effect on the capacitor, and help observe pure "voltage breakdown" rather than "thermal breakdown". The power duty cycle of the pulses is 0.1%-20%, and the peak power duration is 0.1ms-10ms.

[0032] After applying radio frequency power, monitor the state changes of the capacitor under test or the circuit, specifically: Monitoring the state changes of the capacitor under test involves observing whether the capacitor has generated electrical sparks or physical damage using optical equipment. Specifically, optical observation is employed, using a high-speed camera to observe the capacitor under safe and isolated conditions. Breakdown is often accompanied by minute electrical sparks or damage to the physical structure of the device (such as cracks or burn points).

[0033] Monitor the state changes of the circuit: Monitor the output power and reflected power of the circuit, using a sudden drop in output power or a sudden increase in reflected power as the criterion for breakdown. This indicates a drastic change in the circuit impedance state, disrupting the resonance condition, and is usually direct evidence of capacitor breakdown.

[0034] In this embodiment, the output frequency of the RF signal generator (such as the Rohde & Schwarz SMW200A) is set to a precise 13.56 MHz. The output of the signal generator is first connected to an RF power amplifier (such as the AR 50W1000A), and the amplified signal is injected into a series resonant circuit through a directional coupler. The coupling end of the directional coupler is connected to a power meter (such as a Keysight U2000 series USB power sensor) or an oscilloscope for real-time monitoring of forward and reflected power. RF power is applied using a step-by-step power mode, and the state changes of the capacitor and circuit are observed until RF breakdown occurs. In this embodiment, when the power is gradually increased to P = 1000W, physical damage to the capacitor and an increase in reflected power occur simultaneously, which is determined to be a breakdown, and this power value is recorded.

[0035] S4: Voltage calculation: Based on the RF power level P, the quality factor q, the resonant frequency f, and the capacitance value c of the capacitor under test, the RF breakdown voltage V of the capacitor under test is calculated.

[0036] At series resonance, the voltage V across the capacitor is c With input voltage V in The relationship is V c = q·V in The input power P and the input voltage Vin The relationship (for a matched 50-ohm system) is as follows: Substituting the latter equation into the former, we get... In this test circuit, the impedance is lowest at resonance, theoretically equal to the circuit's equivalent series resistance (ESR). The relationship between the quality factor q and ESR is as follows: By combining these formulas, the final expression without explicit ESR can be derived. This expression is used to calculate the RF breakdown voltage V of a high-Q multilayer ceramic capacitor, making the calculation entirely dependent on measurable macroscopic parameters (P, q, f, c), without needing to know the difficult-to-measure internal loss resistance R. This is the key to the ingenuity and practicality of this method. The expression for calculating the RF breakdown voltage V of the capacitor under test is:

[0037] Where P is the radio frequency power at breakdown (in watts), q is the quality factor, f is the resonant frequency (in Hertz), and c is the capacitance of the capacitor under test (in farads). This formula is based on the theory of series resonant circuits, where the voltage across the capacitor is amplified by a factor of q at the resonant point, thus deriving the breakdown voltage from the input power.

[0038] In this embodiment, all recorded parameters are substituted into the core formula:

[0039] Example 2: This example demonstrates the application of the radio frequency breakdown voltage test method for a high-Q multilayer ceramic capacitor at a higher frequency, testing a miniature radio frequency capacitor with a capacitance of c = 10 pF.

[0040] Circuit setup: Match a smaller inductor (e.g., L = 2.5 nH) to the small-capacity capacitor, with the expected resonant frequency f around 1 GHz. At this point, the circuit board must employ a more precise microwave substrate and coplanar waveguide design, and may even require testing within a shielded cavity to eliminate radiation losses.

[0041] Parameter measurement: A VNA capable of covering the GHz band is required. Due to the high frequency, calibration and connector repeatability requirements are more stringent.

[0042] Breakdown testing: At high frequencies, the capacitor's breakdown power may be much lower than in Example 1. More precise power steps (e.g., 0.1W or 0.5W) are required. Furthermore, high-frequency breakdown may be more rapid, necessitating faster monitoring equipment.

[0043] Calculation: Assuming measured values ​​of f = 1 GHz, q = 50, and breakdown power P = 50 W, then the breakdown voltage V is:

[0044] This demonstrates that the method of the present invention is applicable to a wide range of frequencies and voltages.

[0045] In summary, the method provided by this invention effectively tests the breakdown voltage of capacitors under radio frequency conditions, with reliable results, providing accurate data for capacitor quality assessment and circuit design.

[0046] This embodiment also provides a radio frequency breakdown voltage testing system for a high-Q multilayer ceramic capacitor, including a processor and a memory. The memory stores a computer program, and when the computer program is executed by the processor, it implements the radio frequency breakdown voltage testing method for a high-Q multilayer ceramic capacitor.

[0047] Embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0048] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0049] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0050] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0051] Contents not described in detail in this specification are prior art known to those skilled in the art. It is hereby indicated that the above description is intended to help those skilled in the art understand this invention, but does not limit the scope of protection of this invention. Any equivalent substitutions, modifications, improvements, or simplifications of the above descriptions that do not depart from the essential content of this invention fall within the scope of protection of this invention.

Claims

1. A method for testing the radio frequency breakdown voltage of a high-Q multilayer ceramic capacitor, characterized in that, Includes the following steps: S1: Circuit setup: Connect the capacitor under test and the inductor in series to form a series resonant circuit. The capacitor is a high-Q multilayer ceramic capacitor. S2: Parameter measurement to obtain the resonant frequency f and its quality factor q at the resonant frequency point of the series resonant circuit; S3: Breakdown test, apply radio frequency power at the resonant frequency f to the series resonant circuit, and increase the radio frequency power level in an incremental manner, while monitoring the state changes of the capacitor under test or the circuit until it is determined that the capacitor under test has experienced radio frequency breakdown, and record the radio frequency power level P when the breakdown occurs. S4: Voltage calculation: Based on the RF power level P, the quality factor q, the resonant frequency f, and the capacitance value c of the capacitor under test, the RF breakdown voltage V of the capacitor under test is calculated.

2. The method for testing the radio frequency breakdown voltage of a high-Q multilayer ceramic capacitor according to claim 1, characterized in that, In S1: The inductor is an air-wound inductor; The circuit is constructed using a high-frequency circuit board, which employs a microstrip line or coplanar waveguide structure to achieve impedance matching.

3. The method for testing the radio frequency breakdown voltage of a high-Q multilayer ceramic capacitor according to claim 1, characterized in that, In S1: The capacitance value c of the capacitor under test ranges from 0.1 pF to 10 nF; The inductance value L of the inductor is in the range of 1 nH to 1 mH.

4. The method for testing the radio frequency breakdown voltage of a high-Q multilayer ceramic capacitor according to claim 1, characterized in that, The S2 includes: measuring the transmission parameters S21 of the series resonant circuit using a vector network analyzer or an impedance analyzer, obtaining the resonant frequency f by determining the center frequency of the S21 resonant curve, and calculating the quality factor q according to the formula q = f / Δf by measuring the 3dB bandwidth Δf of the resonant curve.

5. The method for testing the radio frequency breakdown voltage of a high-Q multilayer ceramic capacitor according to claim 1, characterized in that: The incremental method of increasing the RF power level described in S3 is a step-power mode, which means applying a continuous wave RF signal and gradually increasing its power value, and maintaining it for a period of time at each power step.

6. The method for testing the radio frequency breakdown voltage of a high-Q multilayer ceramic capacitor according to claim 1, characterized in that: The incremental method of increasing the radio frequency power level described in S3 is a pulsed power mode, that is, applying a series of radio frequency power pulses and gradually increasing the peak power of the radio frequency power pulses. The power duty cycle of the pulses is 0.1%-20%, and the peak power time is 0.1ms-10ms.

7. The method for testing the radio frequency breakdown voltage of a high-Q multilayer ceramic capacitor according to claim 1, characterized in that: The state changes of the capacitor under test described in S3 are observed by optical equipment to determine whether the capacitor generates electrical sparks or physical damage.

8. The method for testing the radio frequency breakdown voltage of a high-Q multilayer ceramic capacitor according to claim 1, characterized in that, The state changes of the circuit described in S3 are monitored in the following ways: The output power and reflected power of the circuit are monitored, and a sudden drop in output power or a sudden increase in reflected power is used as the criterion for determining breakdown.

9. The method for testing the radio frequency breakdown voltage of a high-Q multilayer ceramic capacitor according to claim 1, characterized in that, In S4, the formula for calculating the radio frequency breakdown voltage V is: ； Where P is the RF power at breakdown, q is the quality factor, f is the resonant frequency, and c is the capacitance of the capacitor under test.

10. A radio frequency breakdown voltage testing system for a high-Q multilayer ceramic capacitor, characterized in that, It includes a processor and a memory, the memory storing a computer program that, when executed by the processor, implements a method for testing the radio frequency breakdown voltage of a high-Q multilayer ceramic capacitor according to any one of claims 1-9.

Images