A bidirectional dual-path lightning suppressor

Abstract

This invention relates to the field of semiconductor power device technology. The invention discloses a bidirectional dual-path lightning suppressor, comprising a base, a plastic shell covering the top of the base, the plastic shell and the base forming an inner cavity; a chip is connected to the upper surface of the base via a copper sheet, and a Z-shaped copper lead is electrically connected to the chip; the base, copper sheet, chip, and Z-shaped copper lead are interconnected by lead-tin-silver solder pads, and the inner cavity is filled with epoxy resin; the base serves as the common terminal C, and the Z-shaped copper lead serves as the electrode leads A and B, realizing bidirectional dual-path electrical connection. This invention integrates bidirectional dual-path lightning protection function, high instantaneous current density, high instantaneous power, good heat dissipation performance, small size, light weight, high reliability, and wide environmental adaptability. It solves the problem of traditional lightning protection circuits using multiple products to achieve lightning protection function, and the products are large and heavy. It can be widely used in various lightning protection circuits, effectively reducing the space required, facilitating flexible wiring by users, and has a wide range of applications.

Description

Technical Field

[0001] This invention relates to the field of semiconductor power device technology. Background Technology

[0002] A lightning suppressor is a semiconductor device used to protect electronic equipment from instantaneous high-energy surges such as lightning strikes. Compared to conventional transient voltage suppression diodes, it can withstand higher instantaneous current densities and greater instantaneous power, and is a widely used new type of high-efficiency circuit protection device. It has an extremely fast response time (sub-nanosecond level) and a very high surge absorption capacity. When its terminals are subjected to an instantaneous high-energy surge, it can rapidly change the impedance between its terminals from high impedance to low impedance to absorb a large instantaneous current, thereby clamping the voltage across its terminals to a predetermined value, thus protecting downstream circuit components from the impact of transient high-voltage spike pulses. Therefore, lightning suppressors can be used to protect equipment or circuits from large currents induced by lightning, as well as overvoltages caused by induced lightning.

[0003] Traditional surge protectors typically use a single diode in a single circuit. To achieve dual-circuit functionality, two surge protectors must be added to the same circuit simultaneously, which requires a large installation space and is inconvenient for users. Summary of the Invention

[0004] The purpose of this invention is to provide a bidirectional dual-path lightning suppressor. By improving the internal structure, two single-path bidirectional lightning protection suppressors are integrated into a single diode product, realizing bidirectional dual-path lightning protection function with a single diode. It features small size and high lightning protection performance, and is suitable for various lightning protection application scenarios.

[0005] To address the aforementioned technical problems, this invention provides a bidirectional dual-path lightning suppressor, comprising a base, a plastic shell covering the top of the base, the plastic shell and the base forming an inner cavity; a chip is connected to the upper surface of the base via a copper sheet, and a Z-shaped copper lead is electrically connected to the chip; the base, copper sheet, chip, and Z-shaped copper lead are interconnected by lead-tin-silver solder pads, and the inner cavity is filled with epoxy resin; the base serves as the common terminal C, and the Z-shaped copper lead serves as the electrode leads A and B, achieving bidirectional dual-path electrical connection.

[0006] The base is fixedly connected to the plastic shell, which is made of PPS material. Its long-term operating temperature is 200℃~240℃, the molding shrinkage rate is 0.7%, and the water absorption rate is 0.02%~0.03%.

[0007] The Z-shaped copper lead includes a first Z-shaped copper lead and a second Z-shaped copper lead, which are electrically connected to the chip respectively.

[0008] The first Z-shaped copper lead serves as the first electrode lead-out terminal A, and the second Z-shaped copper lead serves as the second electrode lead-out terminal B.

[0009] Both the base and the copper sheet are made of copper, which has a thermal conductivity of 390–400 W / (m·K) and a specific heat capacity of 386 J / (kg·℃).

[0010] The chip is a glass passivation diode chip, and its PN junction mesa is covered with a glass passivation film, which is a microcrystalline glass structure.

[0011] The lead-tin-silver solder sheet has a melting point of 296°C, and the epoxy resin is a potting type epoxy resin.

[0012] The Z-shaped copper lead has a Z-shaped bending structure.

[0013] The chip is a square lightning suppressor chip, and its surface is provided with a phosphorus-boron diffusion layer and a metal welding layer.

[0014] The air gap between the base, the first Z-shaped copper lead, and the second Z-shaped copper lead is greater than or equal to 2 mm.

[0015] Compared with existing technologies, this invention integrates bidirectional dual-path lightning protection, high instantaneous current density, high instantaneous power, good heat dissipation, small size, light weight, high reliability, and wide environmental adaptability. It solves the problem of using multiple products to achieve lightning protection in traditional lightning protection circuits, which are large and heavy. It can be widely used in various lightning protection circuits, effectively reducing the space required, facilitating flexible wiring by users, and has a wide range of applications.

[0016] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0017] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0018] Figure 1 This is a cross-sectional view of the present invention; Figure 2 This is a schematic diagram of the structure of the present invention.

[0019] In the diagram: 1-base, 2-copper sheet, 3-chip, 4-lead-tin-silver solder sheet, 5-Z-shaped copper lead wire, 6-epoxy resin, 7-plastic shell. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the embodiments of this invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details are presented in the embodiments of this invention to facilitate a better understanding of this application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments. The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of this invention. The embodiments can be combined with and referenced by each other without contradiction.

[0021] Example 1 like Figure 1 and 2 As shown, a YE2-05A plastic-encapsulated bidirectional dual-path lightning suppressor is provided. A copper sheet 2, a chip 3, Z-shaped copper leads 5, and a plastic shell 7 are mounted on a base 1. The base 1, copper sheet 2, chip 3, and Z-shaped copper leads 5 are interconnected by lead-tin-silver solder sheets 4. The plastic shell 7 is bonded to the base 1 with adhesive, and the inner cavity is filled with epoxy resin 6 for protection and sealing. C is the common electrode, and A and B are the two electrode leads, respectively. By using copper as the heat-capacitant material, the instantaneous heat dissipation capacity is improved, enabling the rated surge current withstand capability to reach 6KA (8μs / 20μs).

[0022] Specifically, this invention generates a large amount of heat in a very short time during operation. To ensure the long-term reliability of the device, it is necessary to release this heat in a timely manner to prevent the device from failing due to thermal breakdown. Therefore, the base 1 is thermally designed. After comprehensive analysis of the thermal conductivity, coefficient of thermal expansion, mechanical strength, and compatibility with other materials of different metal materials, copper (Cu) was selected as the heat dissipation material for the base. Utilizing Cu's extremely high thermal conductivity (approximately 390~400 W / (m·K), it can rapidly conduct the heat generated instantaneously by the die to the outside for heat dissipation, ensuring the device can withstand surge currents up to 6KA (8μs / 20μs) and a maximum junction temperature of 150℃. This invention uses copper as the interconnect and heat-capacitance material throughout, which has extremely low resistivity and meets the required hardness, ensuring efficient heat dissipation and surge current resistance up to 6KA (8μs / 20μs).

[0023] Specifically, this invention needs to ensure that the heat of chip 2 can be dissipated and absorbed in a very short time during operation to prevent overheating and breakdown. Therefore, a thick copper material with a thermal conductivity of 390~400 W / (m·K) and a specific heat capacity of 386 J / (kg·℃) is used as the electrode material between the chips. Copper is used as the interconnect and heat-capacitance material throughout, which has extremely low resistivity and meets the hardness requirements, ensuring efficient heat dissipation of the device and surge current resistance of 6KA (8μs / 20μs).

[0024] Specifically, this invention is applied to high-current lightning protection circuits. The higher the current, the stronger the current-bearing capacity of chip 3 needs to be. Therefore, the chip needs a larger area to dissipate heat and absorb surge current. The chip used is a self-designed and developed glass-internal passivated diode chip. Considering the characteristics of low reverse leakage current and high reliability, the mesa passivation protection adopts glass-internal passivation technology. The principle is to grow a glass passivation film on the PN junction mesa to protect the PN junction from contamination by mobile ions and the influence of external conditions on device performance, thereby improving electrical performance, stability, and reliability. The glass passivation film is microcrystalline glass with a glass mesh structure. Its thickness is greater than that of ordinary passivation films, and its surface is dense and free of pinholes. This allows the glass passivation film to largely prevent charged substances that are about to ionize at high temperatures, and to prevent the migration of ions within the film and the intrusion of external ions. In addition, the glass passivation temperature is lower than the thermal oxidation temperature and the time is shorter, reducing the contamination of the single crystal and the generation of dislocation multiplication and lattice degradation caused by prolonged high-temperature treatment.

[0025] Specifically, because the instantaneous operating current is large and the temperature is high, with the maximum operating temperature reaching 150°C, the melting point of the welding material should be much higher than 150°C, and it should have good electrical and thermal conductivity and fatigue resistance, and good thermal matching with the chip. The present invention uses lead-tin-silver solder with a melting point of 296°C, which can meet the requirement of a maximum junction temperature of 150°C under high current operation.

[0026] Specifically, to prevent discharge breakdown at electrodes A, B, and C, an extended Z-shaped copper lead design is adopted to ensure a spacing of ≥2mm between the three terminals (theoretically, a 1mm thick copper electrode with an air gap can withstand 20KA~40KA under an 8μs / 20μs waveform), providing ample installation space for users. Actual measurements show a surge current withstand capability exceeding 7KA (8μs / 20μs), meeting the requirement of a surge current withstand of 6KA (8μs / 20μs).

[0027] Specifically, it is necessary to ensure that the chip is isolated from external moisture and oxygen to prevent chip failure due to the ambient atmosphere. Therefore, the internal structure needs to be sealed and protected. Epoxy resin is used as the potting filler. Epoxy resin has the characteristics of high dielectric strength, high adhesion, high structural strength, good heat resistance, and good structural stability, which meets the requirements of high-current packaging.

[0028] Specifically, the plastic outer shell 7 is made of PPS material, with PPS used as the epoxy resin filling material. This material has the following characteristics: First, it has excellent heat resistance, with a long-term operating temperature of 200℃~240℃, meeting the requirements of high-temperature working environments; second, it has excellent dimensional stability, with extremely low molding shrinkage (approximately 0.7%) and extremely low water absorption (0.02%~0.03%), ensuring dimensional accuracy under high and low temperature or humid environments. Finally, it has excellent electrical insulation properties, effectively preventing current leakage and electrical faults.

[0029] Example 2 One or more internally passivated diodes 3 are connected in series with copper sheets 2, and a plastic shell 7 protects the product. The glass internally passivated diode chip is a square lightning suppressor chip designed and developed in-house. The theoretical current carrying capacity of this size chip is over 16KA, but the actual current carrying capacity will vary depending on the chip process, chip voltage, and heat dissipation conditions. To reduce ohmic contact, phosphorus boron is used as a diffusion source at both ends of the chip, and a metal layer is deposited on the chip surface as a solder layer. Actual testing shows that the chip meets the product's surge current withstand requirement of 6KA (8μs / 20μs). Copper sheets are used as the hot melt material, which can effectively absorb and dissipate the heat generated by the surge current in a very short time. Z-shaped copper leads 5 are used as leads, with one set of Z-shaped copper leads having a common terminal for both paths, another set serving as a bidirectional lead, and the base plate serving as the other bidirectional lead, achieving dual-path bidirectional functionality.

[0030] Through implementation and testing, this invention can withstand a rated surge current of up to 6KA (8μs / 20μs). It can be manufactured into lightning suppressors suitable for different voltage ranges according to the chip voltage and the number of chips. It is anti-static at 4KV and integrates two single-tube lightning suppressors, which is 50% smaller in size than the traditional single-tube method. It adopts a plastic package form, and the operating junction temperature range is -55~150℃. It can withstand temperature cycles of -55~125℃ more than 5 times, and has high reliability.

[0031] Those skilled in the art will understand that the above embodiments can be modified in form and detail in practical applications without departing from the spirit and scope of the invention.

Claims

1. A bidirectional dual-path lightning suppressor, characterized in that: The device includes a base (1), which is covered with a plastic shell (7), and the plastic shell (7) and the base (1) form an inner cavity; the upper surface of the base (1) is connected to a chip (3) by a copper sheet (2), and the chip (3) is electrically connected to a Z-shaped copper lead (5); the base (1), copper sheet (2), chip (3) and Z-shaped copper lead (5) are interconnected by lead-tin-silver solder sheet (4), and the inner cavity is filled with epoxy resin (6); the base (1) serves as the common terminal C, and the Z-shaped copper lead (5) serves as the electrode lead-out terminals A and B, realizing bidirectional dual-path electrical connection.

2. The bidirectional dual-path lightning suppressor as described in claim 1, characterized in that: The base (1) is fixedly connected to the plastic shell (7), which is made of PPS material. Its long-term operating temperature is 200℃~240℃, the molding shrinkage rate is 0.7%, and the water absorption rate is 0.02%~0.03%.

3. The bidirectional dual-path lightning suppressor as described in claim 1, characterized in that: The Z-shaped copper lead (5) includes a first Z-shaped copper lead and a second Z-shaped copper lead, which are electrically connected to the chip (3) respectively.

4. The bidirectional dual-path lightning suppressor as described in claim 3, characterized in that: The first Z-shaped copper lead serves as the first electrode lead-out terminal A, and the second Z-shaped copper lead serves as the second electrode lead-out terminal B.

5. The bidirectional dual-path lightning suppressor as described in claim 1, characterized in that: The base (1) and the copper sheet (2) are both made of copper material, which has a thermal conductivity of 390-400 W / (m·k) and a specific heat capacity of 386 J / (kg·℃).

6. The bidirectional dual-path lightning suppressor as described in claim 1, characterized in that: The chip (3) is a glass passivation diode chip, and its PN junction mesa is covered with a glass passivation film, which is a microcrystalline glass structure.

7. The bidirectional dual-path lightning suppressor as described in claim 1, characterized in that: The lead-tin-silver solder sheet (4) has a melting point of 296°C, and the epoxy resin (6) is a potting epoxy resin.

8. The bidirectional dual-path lightning suppressor as described in claim 1, characterized in that: The Z-shaped copper lead (5) has a Z-shaped bending structure.

9. The bidirectional dual-path lightning suppressor as described in claim 1, characterized in that: The chip (3) is a square lightning suppressor chip with a phosphorus-boron diffusion layer and a metal welding layer on its surface.

10. The bidirectional dual-path lightning suppressor as described in claim 3, characterized in that: The air gap between the base (1), the first Z-shaped copper lead, and the second Z-shaped copper lead is greater than or equal to 2 mm.

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