Method for dissecting axial glass-sealed diode

Abstract

The invention provides a method for dissecting an axial glass-sealed diode. Comprising the following steps: step S01, removing a mark and a coating material outside packaging glass of the axial glass-sealed diode through fuming nitric acid; step S02, performing internal imaging on the axial glass-sealed diode through an X-ray; s03, polishing the axial glass-sealed diode by using a paraffin fixing and mechanical polishing method so as to remove the packaging glass outside the chip; and step S04, enabling the chip to fall off from the electrode column by using fuming nitric acid corrosion and ultrasonic vibration cleaning. According to the invention, the complete unsealing of the internal chip of the axial glass-sealed diode is ensured, the analysis capability of the axial glass-sealed diode is effectively improved, the unsealing efficiency is improved, and the operation safety is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of component failure analysis and destructive physical analysis, and in particular to a method for dissecting an axial glass-sealed diode. Background Art

[0002] The diode can conduct electricity in one direction and has the characteristics of conduction and cutoff, which is equivalent to the on and off of a switch. It can realize multiple functions such as rectification of AC power, detection of modulated signals, limiting and clamping, and voltage stabilization of power supply. Axial glass-sealed diode is a type of diode packaging, most of which are Zener diodes and Schottky diodes. The advantages of axial glass-sealed diodes include: 1. The device is sealed and does not rely on passivation chips to withstand heat and humidity; 2. The thermal expansion coefficients of glass and semiconductors are similar, the device has excellent thermal performance, and allows very high operating temperatures.

[0003] At present, there are two ways to dissect axial glass-sealed diodes: cutting and unsealing with a diamond knife and chemical corrosion with HF acid. Among them, the destructive physical analysis test process generally uses cutting and unsealing with a diamond knife, which has high unsealing efficiency, but low success rate, and is prone to chip damage and the inability to observe the chip surface; failure analysis generally uses HF acid corrosion to ensure that the chip is intact and does not damage the chip structure. HF acid is a dangerous chemical with potential safety hazards. At the same time, HF acid corrosion is slow and takes more than 10 hours. In addition, HF will destroy the passivation layer material on the chip surface, interfering with the analysis.

[0004] Therefore, it is very important to study the appropriate dissection method of axial glass-sealed diodes to improve the unsealing efficiency and reduce safety hazards while completely preserving their internal structure and chips. This is extremely critical for efficiently and correctly analyzing the failure mechanism of axial glass-sealed diodes and giving correct destructive physical analysis results. Summary of the invention

[0005] To solve the above problems, the present invention proposes a method for dissecting an axial glass-sealed diode, which ensures that the internal chip of the axial glass-sealed diode is completely unsealed, effectively improves the analysis capability of the axial glass-sealed diode, and at the same time, improves the unsealing efficiency and ensures the safety of the operation.

[0006] The present invention comprises the following steps:

[0007] Step S01, removing the markings and coating materials on the outside of the encapsulation glass of the axial glass-sealed diode by using fuming nitric acid;

[0008] Step S02, performing internal imaging of the axial glass-sealed diode by X-ray;

[0009] Step S03, polishing the axial glass-sealed diode by paraffin fixation and mechanical polishing to remove the packaging glass outside the chip;

[0010] Step S04, using fuming nitric acid corrosion and ultrasonic vibration cleaning to remove the chip from the electrode column.

[0011] Beneficial effects:

[0012] According to the internal structure of the axial glass-sealed diode, including the frame structure, the chip position, the thickness of the packaging glass at the chip, etc., the present invention uses paraffin fixation and mechanical polishing to remove the packaging glass in the chip area, and adopts fuming nitric acid corrosion and ultrasonic vibration cleaning in acetone to make the chip fall off the electrode column, thereby achieving complete dissection of the glass-sealed axial diode, ensuring that the axial glass-sealed diode device meets the use conditions in analysis work such as failure analysis and destructive physical analysis, while improving the unsealing efficiency and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Flowchart of the present invention

[0014] Figure 2 The figure is a schematic diagram of the basic internal structure of the axial glass-sealed diode involved in the present invention.

[0015] Figure 3 This is a schematic diagram of the axial glass-sealed diode dissected by polishing in the present invention. DETAILED DESCRIPTION

[0016] The preferred embodiment of the present invention will be further described below in conjunction with the accompanying drawings:

[0017] The specific steps of this embodiment are as follows:

[0018] Step S01, using fuming nitric acid to etch away the markings and coating materials on the outside of the encapsulation glass of the axial glass-sealed diode, so that the internal structure can be revealed and observed.

[0019] Step S02, using X-ray to image the interior of the axial glass-sealed diode. Using the characteristics of X-ray's different penetrating abilities for different materials, the axial glass-sealed diode is imaged from the side to determine the internal structure such as the frame structure, chip position, and thickness of the encapsulating glass;

[0020] Step S03, polishing the axial glass-sealed diode according to the chip position inside the axial glass-sealed diode and the thickness of the glass, and removing the packaging glass in the chip area by using paraffin fixation and mechanical polishing.

[0021] The specific process includes: fixing the device on the grinding fixture by paraffin, requiring the paraffin to wrap the device, and polishing the device to the chip position; heating the paraffin, re-fixing the device position, making the unremoved packaging glass face upward, and polishing it to the chip position again; repeating the above steps many times until all the packaging glass around the chip is removed.

[0022] Paraffin fixation ensures that the sample is easy to polish and prepare. At the same time, the paraffin can be heated and melted, making it convenient to polish the sample in different directions.

[0023] Step S04, using fuming nitric acid corrosion and ultrasonic vibration cleaning to make the chip fall off the electrode column, completing the dissection of the axial glass-sealed diode.

[0024] Among them: the temperature of fuming nitric acid is controlled between 80℃ and 90℃, and the time is about 1s to 3s; ultrasonic vibration cleaning is carried out in acetone, the water bath temperature is between 80℃ and 90℃, and the cleaning time is not less than 3min; after cleaning, the detached chips and electrode columns are observed under an optical microscope to confirm whether the structure and morphology are intact.

[0025] Ultrasound in acetone can dissolve the residual paraffin through acetone, and the ultrasonic process makes the chip vibrate continuously in the solution and fall off the chip.

[0026] The present invention realizes the dissection of axial diodes in a simple, safe and efficient way, and ensures the integrity of the internal structure of the device and the cleanness of the chip surface, effectively improving the analysis capabilities of axial glass-sealed diodes, such as failure morphology observation, failure point location and other analyses.

[0027] Although the technical solutions of the present invention have been described with reference to the best embodiments, it is easy for those skilled in the art to understand that the protection scope of the present invention is not limited to these specific embodiments. Without departing from the basic principles of the present invention, the embodiments and the specific technical features therein - such as the modules - may be split, combined or changed, and the technical solutions after splitting, combining or changing will still fall within the protection scope of the present invention.

Claims

1. A method for dissecting an axial glass-sealed diode, characterized in that: include: Step S01, removing the markings and coating materials on the outside of the encapsulation glass of the axial glass-sealed diode by using fuming nitric acid; Step S02, performing internal imaging of the axial glass-sealed diode by X-ray; Step S03, polishing the axial glass-sealed diode by paraffin fixation and mechanical polishing to remove the packaging glass outside the chip; Step S04, using fuming nitric acid corrosion and ultrasonic vibration cleaning to remove the chip from the electrode column.

2. The method for dissecting an axial glass-sealed diode according to claim 1, characterized in that: The specific process of S01 is: using fuming nitric acid to corrode the markings and coating materials outside the packaging glass of the axial glass-sealed diode, so that the internal structure can be revealed and observed.

3. The method for dissecting an axial glass-sealed diode according to claim 1, characterized in that: The specific process of S02 is: perspective imaging the axial glass-sealed diode from its side.

4. The method for dissecting an axial glass-sealed diode according to claim 1, characterized in that: The specific process of S03 is: fix the device on the grinding fixture by paraffin wax, require the paraffin wax to wrap the device, and polish the device to the chip position; heat the paraffin wax, re-fix the device position, make the unremoved packaging glass face upward, and polish it to the chip position again; repeat the above steps many times until the packaging glass around the chip is completely removed.

5. The method for dissecting an axial glass-sealed diode according to claim 1, characterized in that: The specific process of S04 is: using fuming nitric acid corrosion and ultrasonic vibration cleaning to make the chip fall off the electrode column, wherein: the temperature of the fuming nitric acid is controlled between 80°C and 90°C, and the time is about 1s to 3s; the ultrasonic vibration cleaning is carried out in acetone, the water bath temperature is between 80°C and 90°C, and the cleaning time is not less than 3min; after cleaning, the detached chip and electrode column are observed under an optical microscope to confirm whether the structure and morphology are intact.

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