A method for positioning open circuit position of metal film chip resistor

Abstract

The application discloses a positioning method for open-circuit position of metal film chip resistor, comprising the following steps: S1, repeatedly loading voltage on the defective resistor, so that the metal resistor film at the open-circuit position is fused to generate a morphology feature different from resistor films at other positions, measuring the resistance value after voltage loading, and stopping loading voltage after the resistance value decreases; S2, using a solvent to open the resistor, so as to dissolve the protective layer of the chip resistor; S3, cleaning the sample, so that the sample surface is free of solvent residues, and then taking out the sample and placing it on filter paper for drying; S4, observing the sample. The method for opening the resistor after voltage loading not only changes the morphology feature of the resistor film at the open-circuit position, but also can etch the resistor film completely and intact, so that the characteristic resistor film can be clearly observed, and the open-circuit position can be accurately positioned.

Description

Technical Field

[0001] This invention relates to the field of component failure analysis technology, and in particular to a method for locating the open circuit position of a metal film chip resistor. Background Technology

[0002] Nickel-chromium metal film resistors use a nickel-chromium alloy as the resistive material, and a resistive film layer is formed on a ceramic or glass substrate using vacuum evaporation or sputtering methods. These resistors are generally manufactured using a vacuum evaporation process, where the alloy is heated in a vacuum, causing it to evaporate and forming a conductive metal film on the surface. The resistance value can be controlled by grooving and changing the thickness of the metal film. They exhibit excellent electrical properties such as heat resistance, noise potential, temperature coefficient, and voltage coefficient. The manufacturing process of metal film resistors is relatively flexible; not only can the material composition and film thickness be adjusted, but the resistance value can also be adjusted by grooving, thus allowing for the production of resistors with good performance and a wide resistance range. In this invention, the thickness of the nickel-chromium resistive film is only a few nanometers to tens of nanometers, making it almost impossible to accurately locate open circuits using conventional methods. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a method for locating the open circuit position of a surface mount resistor, so as to accurately locate the open circuit position of the resistor.

[0004] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0005] A method for locating the open circuit position of a metal film chip resistor, the method comprising the following steps:

[0006] S1. Repeatedly apply voltage to the faulty resistor to melt the metal resistive film at the open circuit position, resulting in a morphological feature different from that of the resistive film at other positions. Measure the resistance value after applying voltage, and stop applying voltage when the resistance value decreases.

[0007] S2. Use a solvent to open the resistor, thereby dissolving the protective layer of the chip resistor;

[0008] S3. Clean the sample to ensure no solvent residue remains on the sample surface, then remove the sample and place it on filter paper to dry.

[0009] S4. Observe any abnormalities on the sample.

[0010] Furthermore, a semiconductor parameter analyzer is connected to both ends of the resistor using a probe station. A voltage of 20-70V is applied to the failed resistor for 2-25 seconds, and the application is repeated 2-10 times.

[0011] Furthermore, a combination of a power supply and probes at both ends of the contactable resistor can be used to apply voltage to the failed resistor.

[0012] Furthermore, the resistance is heated for 1-10 minutes using concentrated sulfuric acid at 150℃-300℃.

[0013] Furthermore, the solvent was poured out, and water was added repeatedly to the beaker to wash the sample in a rice-washing manner.

[0014] Furthermore, after pouring out most of the water from the beaker, use a disposable dropper to draw up the sample and place it on filter paper to dry.

[0015] Furthermore, after pouring out most of the water from the beaker, use tweezers to pick up the sample and place it on filter paper to dry.

[0016] Furthermore, after step S3, after confirming that the sample surface is clean, the sample is placed in a beaker containing cleaning solvent for ultrasonic cleaning.

[0017] Furthermore, the cleaning solvent is selected from alcohols, preferably anhydrous ethanol; the ultrasonic cleaning time is 10-90 seconds.

[0018] Furthermore, after ultrasonic cleaning, the sample is transferred to filter paper for drying using a disposable dropper or tweezers.

[0019] Furthermore, metallographic polarizing microscopes were used to detect anomalies on the samples;

[0020] Or use an electron microscope to observe abnormalities on the sample;

[0021] Alternatively, anomalies on the sample can be identified by combining metallographic polarizing microscope and electron microscope.

[0022] Further, after step S4, the resistance at both ends of the abnormal location is measured using a probe station and a multimeter.

[0023] Compared with the prior art, the beneficial effects of the embodiments of the present invention are as follows:

[0024] This invention provides a method for locating the open circuit position of a metal film chip resistor. This method can cleanly and completely etch out the resistive film in the chip resistor without damaging the resistive film, and can accurately locate the open circuit position on the resistive film after characterization, thus solving the problem of the inability to locate the open circuit position of the chip resistor. Attached Figure Description

[0025] Figure 1 This is a flowchart of the implementation steps of the present invention;

[0026] Figure 2 This is a schematic diagram of the sample before it is opened.

[0027] Figure 3 A schematic diagram showing the opening of the sample after applying voltage; Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0029] Existing techniques primarily utilize optical microscopy to observe the surface for signs of mechanical cracks and thermal damage, followed by the use of N,N-dimethylformamide to dissolve the surface resin layer and observe the internal morphology for defect localization. This conventional method has the following problems: ① After removing the surface resin protective layer with N,N-dimethylformamide, a layer of glass glaze may remain on the resistive film surface, making it impossible to directly observe and analyze the resistive film layer; ② Even when the resistive layer can be directly observed, the resistive film layer produced by vacuum evaporation is extremely thin, resulting in almost no obvious features at open circuit or defect locations, making it difficult to locate open circuits under optical and electron microscopes.

[0030] To address the shortcomings of the existing technology, embodiments of the present invention provide a method for locating the open circuit position of a metal film patch resistor, such as... Figure 1 As shown, the implementation steps of this method are as follows:

[0031] Step 1: Apply voltage to the faulty resistor.

[0032] First, the resistance of the unopened circuit is measured to confirm it is an open-circuit resistor. Then, a semiconductor parameter analyzer is connected to the faulty resistor using a probe station. Voltage is applied to the faulty resistor, and repeated voltage application changes the morphological characteristics of the resistive film at the open-circuit location, making it clearly different from the resistance at the normal location. The actual number of voltage applications is determined by measuring the resistance value after each voltage application; voltage is stopped when the resistance decreases. The morphology of the open-circuit location becomes characteristic after the resistance decreases, facilitating later observation.

[0033] In this embodiment, the voltage is applied by connecting a probe station to a semiconductor parameter analyzer and a faulty resistor. In other embodiments, a combination of a power supply and probes with electrodes at both ends of the accessible resistor can be used to apply voltage to the faulty resistor, thus achieving the function of applying voltage to the resistor.

[0034] Step 2: Unseal the resistor.

[0035] After applying voltage, the resistor needs to be unsealed. In this embodiment, the unsealing solvent is concentrated sulfuric acid. When unsealing, concentrated sulfuric acid is poured into the beaker containing the resistor, so that the resistor is immersed in the concentrated sulfuric acid. The beaker is heated. The concentrated sulfuric acid, as the unsealing solvent, can dissolve the protective layer of the resistor, thus completing the unsealing of the resistor.

[0036] Step 3: Cleaning.

[0037] After the protective layer on the surface of the resistor has completely dissolved, pour out the concentrated sulfuric acid from the beaker, leaving the sample in the beaker. Then add water to the beaker to wash the sample. After washing, pour out the water and continue to add water to the beaker to wash the sample. This is called washing the sample like rinsing rice to ensure that there is no concentrated sulfuric acid residue on the sample surface in order to proceed to the next step.

[0038] Pour out most of the water from the final rice-rinse, leaving only the sample and a small amount of water at the bottom of the beaker. This water should be as little as possible. Then, take out a transparent disposable dropper and squeeze the closed end of the dropper so that the bottom of the open end is close to the sample. Then, release the closed end of the dropper, allowing the open end to use negative pressure to draw the sample along with a small amount of water onto the dropper. In actual operation, it is important to note that the water and sample must be adsorbed at the bottom of the open end of the dropper, and the sample must still be surrounded by water. Do not forcefully draw the sample or let it stick to the dropper wall.

[0039] In this embodiment, a transparent disposable dropper is used to remove the sample; in other embodiments, tweezers may be used.

[0040] After the sample is removed, it is transferred to filter paper for drying. Once the sample is dry and its surface is confirmed to be clean, it is placed in a beaker containing a cleaning solvent. In this embodiment, the cleaning solvent is anhydrous ethanol; in other embodiments, the cleaning solvent can be other types of alcohol. After the sample is placed in the beaker containing anhydrous ethanol, it is ultrasonically cleaned to further remove residues from the sample surface. After cleaning, most of the anhydrous ethanol is poured out, and the sample is removed using the same method as after rice washing. In this embodiment, a transparent disposable dropper is used for removal; in other embodiments, tweezers can be used to remove the sample.

[0041] Step 4: Observe for abnormalities.

[0042] After the sample is dried, it is placed under a microscope for observation. In this embodiment, a metallographic polarizing microscope is selected for observation. In other embodiments, an electron microscope or a combination of a metallographic polarizing microscope and an electron microscope can also be selected to observe and determine the abnormal location on the sample.

[0043] After identifying the abnormal location, place the probe station at both ends of the abnormal location and connect it to a multimeter. Use the probe station and multimeter to measure the resistance at both ends of the abnormal location.

[0044] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0045] Example 1

[0046] This embodiment provides a method for locating the open circuit position of a metal film patch resistor. The specific steps of this embodiment include: S1, applying a voltage of 20V to an unopened resistor, with each voltage application lasting 25 seconds and repeated 10 times; S2, opening the sealed resistor by pouring concentrated sulfuric acid into a beaker containing the resistor, with the concentrated sulfuric acid heated to 150°C for 10 minutes; S3, washing the sample with water using a rice-washing method, then transferring the sample to filter paper for drying using a disposable dropper, followed by ultrasonic cleaning in a beaker containing anhydrous ethanol for 10 seconds, and then transferring the sample to filter paper again for drying using a disposable dropper; S4, observing the dried sample using a metallographic polarizing microscope to confirm the abnormal position, and then measuring the resistance at both ends of the abnormal position using a probe station and a multimeter to determine whether the abnormal position is an open circuit.

[0047] Example 2

[0048] This embodiment provides a method for locating the open circuit position of a metal film patch resistor. The specific steps of this embodiment include: S1, applying a voltage of 70V to an unopened resistor, with each voltage application lasting 2 seconds and repeated twice; S2, opening the sealed resistor by pouring concentrated sulfuric acid into a beaker containing the resistor, with the concentrated sulfuric acid heated to 300℃ for 1 minute; S3, washing the sample with water using a rice-washing method, then transferring the sample to filter paper for drying using a disposable dropper, followed by ultrasonic cleaning in a beaker containing anhydrous ethanol for 90 seconds, and then transferring the sample to filter paper again for drying using a disposable dropper; S4, observing the dried sample using a metallographic polarizing microscope to confirm the abnormal position, and then measuring the resistance across the abnormal position using a probe station and a multimeter to determine whether the abnormal position is an open circuit.

[0049] Example 3

[0050] This embodiment provides a method for locating the open circuit position of a metal film chip resistor. Figure 2The specific steps of this embodiment for obtaining the resistance diagram before opening include: S1, applying a voltage of 50V to the unopened resistor, with each voltage application lasting 10 seconds, and repeating this process 4 times; S2, opening the resistor after applying the voltage by pouring concentrated sulfuric acid into the beaker containing the resistor, with the concentrated sulfuric acid heated to 200°C for 4 minutes; S3, washing the sample with water using a rice-washing method, then transferring the sample to filter paper for drying using a disposable dropper, followed by ultrasonic cleaning in a beaker containing anhydrous ethanol for 60 seconds, and then transferring the sample to filter paper again for drying using a disposable dropper; S4, observing the dried sample using a metallographic polarizing microscope to identify abnormal locations, and then measuring the resistance across the abnormal location using a probe station and a multimeter to determine if the abnormal location is an open circuit. Figure 3 As shown, after the above operations, point 1 is an abnormal location observed by a metallographic microscope. After measuring the resistance at both ends, it was confirmed that the abnormal location is an open circuit.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of locating an open circuit location of a metal film chip resistor, comprising: The method comprises the steps of: S1, repeatedly loading voltage on the defective resistor, melting the metal resistance film at the open circuit position to generate a morphology feature different from the resistance film at other positions, measuring the resistance value after the voltage is loaded, stopping loading the voltage when the resistance value decreases, connecting the semiconductor parameter analyzer to the two ends of the resistor by the probe station, loading voltage on the failed resistor, the voltage being 20-70V, the time being 2-25S, and the loading times being 2-10 times; S2, opening the resistor by using a solvent to dissolve the protective layer of the chip resistor, i.e., heating the resistor by concentrated sulfuric acid at 150-300℃ for 1-10min; S3, cleaning the sample to remove the solvent on the surface of the sample, and then taking out the sample and placing it on filter paper to dry; S4, observing the abnormality on the sample.

2. The method of claim 1, wherein the metal film chip resistor open circuit location is determined by: The repeatedly loading voltage on the defective resistor further comprises: loading voltage on the failed resistor by combining the power supply with the probe capable of contacting the electrodes at the two ends of the resistor.

3. The method of claim 1, wherein the metal film chip resistor open circuit location is determined by: The cleaning the sample comprises: pouring out the solvent, and repeatedly adding water to the beaker to clean the sample in a rice washing manner.

4. The method of claim 1, wherein the metal film chip resistor open circuit location is determined by: The taking out the sample and placing it on filter paper to dry comprises:

5. The method of claim 1, wherein the metal film chip resistor open circuit location is determined by: after pouring out most of the water in the beaker, using a disposable dropper to take the sample and placing it on filter paper to dry. The taking out the sample and placing it on filter paper to dry comprises:

6. The method of claim 1, wherein the metal film chip resistor open circuit location is determined by: after pouring out most of the water in the beaker, using tweezers to take the sample and placing it on filter paper to dry. After step S3, the method further comprises:

7. The method of claim 6, wherein the metal film chip resistor open circuit location is determined by: after confirming that the surface of the sample is clean, placing the sample in a beaker containing a cleaning solvent and performing ultrasonic cleaning.

8. The method of claim 6, wherein the metal film chip resistor open circuit location is determined by: The cleaning solvent is selected from one of alcohols, and the alcohol is anhydrous ethanol; the ultrasonic cleaning time is 10-90S.

9. The method of claim 1, wherein the metal film chip resistor open circuit location is determined by: After ultrasonic cleaning, the sample is transferred to filter paper to dry by using a disposable dropper or tweezers. The observing the abnormality on the sample comprises: detecting the abnormality on the sample by using a metallographic polarized light microscope; or observing the abnormality on the sample by using an electron microscope; 10. The method of claim 1, wherein the metal film chip resistor open circuit location is determined by: or determining the abnormality on the sample by combining a metallographic polarized light microscope and an electron microscope. After step S4, the method further comprises: measuring the resistance at the two ends of the abnormal position by using a probe station and a multimeter.

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