A glassy passivation plastic package surface mount diode and a manufacturing process thereof

Abstract

The application provides a glass-plastic plastic-sealed surface-mounted diode and a manufacturing process thereof, which comprises a pipe core, two ends of the pipe core are connected with two molybdenum electrodes respectively, outer ends of the two molybdenum electrodes are connected with two copper electrodes respectively, the two copper electrodes are connected through plastic packaging, and the side surface of the pipe core is wrapped through glass packaging. The pipe core is packaged through glass packaging, the diode as a whole is packaged through a plurality of packaging, the advantages of high-temperature stability, strong anti-radiation capacity, high reliability and the like of ceramic packaging can be obtained, the defect of high manufacturing cost limitation can be avoided, the diode after packaging is more adaptable, small in size, various in shape size specifications, has the advantages of two packaging modes, meets the requirements of miniaturization, light weight, simple process, easy batch production and low cost of an electronic system, and is various in shape, such as square and cylindrical, is convenient to install in use, and is high in stability.

Description

Technical Field

[0001] This invention relates to a glass passivated plastic-encapsulated surface-mount diode and its manufacturing process. Background Technology

[0002] Early semiconductor packaging primarily used ceramic packaging. With the increasing integration and speed of semiconductor devices, the miniaturization of electronic devices, and the reduction in price, ceramic packaging has been partially replaced by plastic packaging. However, ceramic packaging still has many irreplaceable functions. In particular, the increasing operating frequency of integrated circuit components, the faster signal transmission speed, and the increased chip power consumption mean that ceramic packaging cannot be completely replaced. Ceramic packaging, with its advantages of high-temperature stability, strong radiation resistance, and high reliability, is widely used in low-, mid-, and high-end fields. However, its high manufacturing cost limits its use in the mid- to high-end market. Plastic packaging, due to its low cost, simple process, and suitability for mass production, is widely used in packaging. However, due to the reliability limitations of plastic-packaged devices, it can only be used in the low- to mid-range market. For example, a glass-passivated surface-mount diode disclosed in CN217847937U achieves diode miniaturization by bending two molybdenum electrodes in the same direction and encapsulating the die with glass. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a glass-passivated plastic-encapsulated surface-mount diode and its manufacturing process.

[0004] The present invention is achieved through the following technical solutions.

[0005] The present invention provides a glass passivation plastic-encapsulated surface mount diode, comprising a die, two ends of which are respectively connected to two molybdenum electrodes, the outer ends of which are respectively connected to two copper electrodes, the two copper electrodes being encapsulated by a plastic encapsulation, and the side of the die being further encapsulated by a glass encapsulation.

[0006] The diameter of the die is smaller than the diameter of the molybdenum electrode.

[0007] A fabrication process for a glass-passivated, plastic-encapsulated surface-mount diode includes the following steps:

[0008] 1) Polish one side of the silicon wafer to a thickness of 200-350μm. The resistivity of the polished silicon wafer is 0.003~500Ω·cm.

[0009] 2) Phosphorus and boron diffusion is performed on the silicon wafer to form a phosphorus junction with a depth of 10-80 μm and a sheet resistance of ≤3Ω; and a boron junction with a depth of 10-80 μm and a sheet resistance of ≤5Ω.

[0010] 3) Sandblasting is performed on the silicon wafer to remove the borosilicate glass layer formed by boron diffusion on the surface of the silicon wafer;

[0011] 4) Aluminum is evaporated onto the phosphorus diffusion surface of the silicon wafer, and then alloyed. The thickness of the aluminum layer is 6-16 μm.

[0012] 5) Cut the silicon wafer to obtain the die, immerse the die in acid solution for 80-180 seconds, rinse with cold deionized water and dehydrate with alcohol and then dry.

[0013] 6) Connect one end of each of the two cylindrical molybdenum electrodes to a thin circular copper sheet of the same diameter;

[0014] 7) Weld the exposed end faces of the two molybdenum electrodes to both ends of the die;

[0015] 8) After etching the tube core in an alkaline solution, it is then passivated in a passivation solution;

[0016] 9) A glass encapsulation is formed on the outer wall of the die along the misalignment between the molybdenum and the die;

[0017] 10) After the glass passivation and encapsulation are completed, connect the copper-plated side of the molybdenum electrode to the copper electrode sheet;

[0018] 11) After the copper electrode sheets are connected, they are placed in a molding die for molding.

[0019] The volume ratio of HF to HNO3 in the acid solution is 1:5.

[0020] The molybdenum electrode is connected to the round copper sheet by melting at a temperature of 1100°C.

[0021] In step 7, welding is performed using vacuum sintering, with a vacuum degree ≥ 3.4 × 10⁻⁶. -3 Pa, heat to 660-700℃ at a heating rate of 5-25℃ / min and hold at that temperature for 2-5 minutes; then cool to 100℃ at a cooling rate of ≤5℃ / min.

[0022] The alkaline solution is a 2-12% KOH solution. During the corrosion process, the solution is corroded at 80℃-100℃ for 2-25 minutes. After corrosion, it is rinsed with hot deionized water, then boiled in hot deionized water 5 times, and finally rinsed with hot and cold deionized water alternately for more than half an hour. The passivation solution is a mixture of ≥30% hydrogen peroxide, ≥85% hydrogen peroxide, and deionized water in a mass ratio of 1:1:1.3.

[0023] In step 9, the passivated core and the welded molybdenum electrode sheet are placed into an automatic glass powder coating machine to coat them with glass powder, so that the glass powder covers the staggered layers of molybdenum and core with a coating thickness of 1 mm. Then, the mold is placed into a sintering furnace. The sintering furnace is heated to 660°C at a heating rate of 5-25°C / min and held for 2-15 min. Then, it is cooled to room temperature at a cooling rate of ≤5°C / min. Then, the mold is removed and shaped.

[0024] In step 10, a solder paste is applied to the copper side of the molybdenum electrode, and then the two sides are welded together by vacuum reflow soldering at a temperature of about 350°C.

[0025] In step 11, the glass-encapsulated core is placed into a molding die, and then placed into a molding machine for injection and molding to complete the plastic encapsulation. After cooling to room temperature, it undergoes shaping processes such as trimming.

[0026] The beneficial effects of this invention are as follows: by encapsulating the die with glass and the diode as a whole through mass encapsulation, it can achieve the advantages of ceramic encapsulation, such as high temperature stability, strong radiation resistance, and high reliability, while avoiding the defects of being limited by high manufacturing costs. After encapsulation, the diode is more adaptable, smaller in size, and available in various sizes. It has the advantages of two encapsulation methods, meeting the requirements of miniaturization, lightweighting, simple process, easy mass production, and low cost of electronic systems. In addition, it has a variety of shapes, such as square and cylindrical, which are easy to install and have strong stability during use. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the present invention;

[0028] In the diagram: 1-die, 2-glass encapsulation, 3-copper electrode, 4-plastic encapsulation, 5-molybdenum electrode. Detailed Implementation

[0029] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0030] This application combines the advantages of both ceramic and plastic encapsulation methods, achieving the high-temperature stability, strong radiation resistance, and high reliability of ceramic encapsulation while avoiding the limitations imposed by high manufacturing costs. This patent combines the advantages of ceramic and plastic encapsulation to invent a novel glass-passivated plastic-encapsulated surface-mount diode. This results in a more adaptable and smaller diode with various dimensions, combining the advantages of both encapsulation methods. It meets the requirements of miniaturization, lightweight design, simple manufacturing process, easy mass production, and low cost in electronic systems. Furthermore, it offers a variety of shapes, including square and cylindrical, facilitating installation and providing high stability. Its structure includes a chip, glass passivated encapsulation, plastic encapsulation, and copper-molybdenum electrodes.

[0031] Example 1: The diode is fabricated as follows:

[0032] 1. Polish one side of the silicon wafer; the thickness after polishing is 200-350μm, and the resistivity is 0.003-500Ω·cm.

[0033] 2. Perform phosphorus-boron diffusion on the silicon wafer to form a phosphorus junction depth of 10-80μm with a sheet resistance ≤3Ω; a boron junction depth of 10-80μm with a sheet resistance ≤5Ω; the diffusion temperature is 1100-1280℃ and the diffusion time is 5-50h.

[0034] 3. The silicon wafer is sandblasted to remove the borosilicate glass layer formed by boron diffusion on the surface. Sandblasting is performed using compressed air carrying 302# or 303# diamond abrasive, at a pressure of 0.1 × 10⁻⁶. 5 pa-5×10 5 pa.

[0035] 4. Aluminum is evaporated onto the phosphorus diffusion surface of the silicon wafer, and then alloyed. The thickness of the aluminum layer is 6-16μm. The alloying temperature is 450-550℃, and the holding time is 5-20min.

[0036] 5. Cut the silicon wafer to obtain the die, and etch the die in an acid solution; the volume ratio of HF to HNO3 in the acid solution is 1:5, the etching time is 80-180s, and after etching, rinse with cold deionized water and dehydrate with alcohol and then dry.

[0037] 6. Connect the molybdenum to the thin circular copper sheet; place the thin circular copper sheet at one end of the molybdenum and melt it at a high temperature of 1100℃. The copper sheet will then melt into molten copper. After it cools to room temperature, a copper surface will form at one end of the molybdenum.

[0038] 7. Weld two unburnt molybdenum copper surfaces to both sides of the core; sintering vacuum degree.

[0039] ≥3.4×10 -3 Pa, heat to 660-700℃ at a heating rate of 5-25℃ / min and hold at that temperature for 2-5 minutes; then cool to 100℃ at a cooling rate of ≤5℃ / min.

[0040] 8. After etching the tube core in an alkaline solution, place it in a passivation solution for passivation. The alkaline solution is a 2-12% KOH solution. During etching, the core should be etched at 80℃-100℃ for 2-25 minutes. After etching, rinse with hot deionized water, then boil in hot deionized water five times. Finally, rinse with alternating hot and cold deionized water for at least half an hour. The passivation solution is a mixture of ≥30% hydrogen peroxide, ≥85% hydrogen peroxide, and deionized water in a mass ratio of 1:1:1.3. The passivation time is 1-10 minutes.

[0041] 9. Form a glass encapsulation along the misalignment between the molybdenum and the core on the outer wall of the core; place the passivated core and the welded molybdenum electrode sheet into an automatic glass powder coating machine to coat them with glass powder, so that the glass powder covers the misalignment between the molybdenum and the core with a coating thickness of 1 mm. Then, place the mold together into a sintering furnace, and heat the furnace to 660°C at a heating rate of 5-25°C / min and hold for 2-15 min. Then, cool it to room temperature at a cooling rate of ≤5°C / min. Then, remove the mold and shape it.

[0042] 10. After the glass passivation and encapsulation are completed, connect the molybdenum-copper side to the copper electrode sheet. Since there is a layer of copper on the molybdenum-copper side, add solder paste to bond the center of the copper electrode sheet to the copper sheet. The two sides can be firmly welded by vacuum reflow soldering at a temperature of about 350°C.

[0043] 11. After the copper electrode sheets are connected, they undergo appropriate processing and are placed into a molding die for molding. The glass-encapsulated core is placed into the corresponding molding die, and then placed into a molding machine for injection and molding to complete the plastic encapsulation. After cooling to room temperature, it undergoes shaping processes such as trimming.

[0044] By combining glass passivation encapsulation and plastic encapsulation, the encapsulated diodes are more adaptable, smaller in size, and available in various dimensions. They offer the advantages of both encapsulation methods, meeting the requirements of miniaturization, lightweighting, simple manufacturing process, easy mass production, and low cost in electronic systems, and are also easy to install during use.

[0045] By flat-soldering the molybdenum electrode onto the die, the glass package only needs to cover the staggered layers surrounding the molybdenum and the die, making the subsequent plastic-encapsulated surface mount diode more miniaturized, lighter, and thinner.

[0046] This enables the glass passivated plastic-encapsulated surface mount diode to withstand thermal fatigue of over 30,000 cycles, far exceeding the approximately 3,000 cycles of plastic-encapsulated surface mount diodes and ceramic diodes.

[0047] Both ends of the molybdenum electrode are exposed, with the entire surface serving as a contact surface and all of them being effective. This allows it to be completely soldered onto the circuit board, ensuring the stability of the diode during use and avoiding malfunctions caused by poor contact.

[0048] The glass-passivated plastic-encapsulated surface-mount diodes come in a variety of shapes, including square, rectangular, and cylindrical, to better meet different application conditions. The molybdenum electrode has a large facet on one end and a small facet on the other, with an overall convex shape, which facilitates the welding of the die and the production of molds for glass and plastic encapsulation.

Claims

1. A manufacturing process for a glass passivation plastic-encapsulated surface mount diode, wherein the glass passivation plastic-encapsulated surface mount diode includes a die (1), the two ends of the die (1) are respectively connected to two molybdenum electrodes (5), the outer ends of the two molybdenum electrodes (5) are respectively connected to two copper electrodes (3), the two copper electrodes (3) are encapsulated by a plastic encapsulation (4), and the side of the die (1) is also wrapped by a glass encapsulation (2); Its features are: The manufacturing process of the glass passivation plastic-encapsulated surface-mount diode includes the following steps: 1) Polish one side of the silicon wafer to a thickness of 200-350μm. The resistivity of the polished silicon wafer is 0.003~500 Ω·cm. ; 2) Phosphorus and boron diffusion is performed on the silicon wafer to form a phosphorus junction with a depth of 10-80 μm and a sheet resistance of ≤3Ω; and a boron junction with a depth of 10-80 μm and a sheet resistance of ≤5Ω. 3) Sandblasting is performed on the silicon wafer to remove the borosilicate glass layer formed by boron diffusion on the surface of the silicon wafer; 4) Aluminum is evaporated onto the phosphorus diffusion surface of the silicon wafer, and then alloyed. The thickness of the aluminum layer is 6-16 μm. 5) Cut the silicon wafer to obtain the die, immerse the die in acid solution for 80~180s for etching, rinse with cold deionized water and dehydrate with alcohol and then dry. 6) Connect one end of each of the two cylindrical molybdenum electrodes to a thin circular copper sheet of the same diameter; 7) Weld the exposed end faces of the two molybdenum electrodes to both ends of the die; 8) After etching the tube core in an alkaline solution, it is then passivated in a passivation solution; 9) A glass encapsulation is formed on the outer wall of the die along the misalignment between the molybdenum and the die; 10) After the glass passivation and encapsulation are completed, connect the copper-plated side of the molybdenum electrode to the copper electrode sheet; 11) After the copper electrode sheets are connected, they are placed in a molding die for molding.

2. The glass-passivated plastic-encapsulated surface-mount diode as described in claim 1, characterized in that: The diameter of the core (1) is smaller than the diameter of the molybdenum electrode (5).

3. The manufacturing process of the glass passivation molded surface mount diode as described in claim 1, characterized in that: The volume ratio of HF to HNO3 in the acid solution is 1:

5.

4. The fabrication process of the glass passivation molded surface mount diode as described in claim 1, characterized in that: The molybdenum electrode is connected to the round copper sheet by melting at a temperature of 1100°C.

5. The manufacturing process of the glass passivation molded surface mount diode as described in claim 1, characterized in that: In step 7), welding is performed using vacuum sintering, and the vacuum level during sintering is... Heat the temperature to 660-700℃ at a heating rate of 5-25℃ / min and hold it at that temperature for 2-5 minutes; then cool it down to 100℃ at a cooling rate of ≤5℃ / min.

6. The fabrication process of the glass passivation molded surface mount diode as described in claim 1, characterized in that: The alkaline solution is a 2-12% KOH solution. During the corrosion process, the solution is corroded at a temperature of 80℃-100℃ for 2-25 minutes. After corrosion, the solution is rinsed with hot deionized water, then boiled in hot deionized water 5 times. Finally, the solution is rinsed with hot and cold deionized water alternately for more than half an hour. The passivation solution is a mixture of ≥30% hydrogen peroxide, ≥85% hydrogen peroxide and deionized water in a mass ratio of 1:1:1.

3.

7. The manufacturing process of the glass passivation molded surface mount diode as described in claim 1, characterized in that: In step 9), the passivated core and the welded molybdenum electrode sheet are placed in an automatic glass powder coating machine to coat them with glass powder, so that the glass powder covers the staggered layers of molybdenum and core with a coating thickness of 1 mm. Then, the mold is placed in a sintering furnace. The sintering furnace is heated to 660°C at a heating rate of 5-25°C / min and held for 2-15 min. Then, it is cooled to room temperature at a cooling rate of ≤5°C / min. Then, the mold is removed and shaped.

8. The fabrication process of the glass passivation molded surface mount diode as described in claim 1, characterized in that: In step 10), a solder paste is applied to the copper side of the molybdenum electrode, and then the two sides are welded together by vacuum reflow soldering at a temperature of about 350°C.

9. The fabrication process of the glass passivation molded surface mount diode as described in claim 1, characterized in that: In step 11), the glass-encapsulated core is placed into a molding die, and then placed into a molding machine for injection and molding to complete the plastic encapsulation. After cooling to room temperature, it is then subjected to shaping processes such as trimming.

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