Semiconductor package structure with temperature uniformity function and packaging method thereof

Abstract

The application provides a semiconductor structure with a temperature equalizing function and a packaging method, which comprises a plastic encapsulating layer, a frame base island, frame pins, metal leads and a chip; the frame base island is composed of an upper shell plate, a lower shell plate, a liquid absorbing core and a powder column; the chip is welded on the frame base island and connected with the frame pins through the metal leads; the frame base island is generally wrapped in the plastic encapsulating layer, and the bottom surface of the frame base island and the frame pins are exposed outside the plastic encapsulating layer; the upper surface of the plastic encapsulating layer is provided with micro grooves; the upper shell plate, the lower shell plate, the liquid absorbing core and the powder column are prepared by using a temperature equalizing plate. By using the temperature equalizing plate and high-thermal-conductivity fillers, the thermal conductivity of the frame base island and the plastic encapsulating layer is greatly improved; by arranging the micro grooves, the heat dissipation area of the upper surface of the plastic encapsulating layer is increased, the heat dissipation capacity of the heat dissipation channel on the upper part of the chip is further improved, the thermal stress of the semiconductor during operation is effectively reduced, and the service life and reliability of the semiconductor are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor packaging technology, specifically relating to a semiconductor packaging structure with temperature equalization function and its packaging method. Background Technology

[0002] Semiconductor plastic-encapsulated devices (collectively referred to as semiconductor packaging structures) are widely used in various fields such as home appliances and new energy vehicles due to their simple manufacturing process and low cost. However, existing semiconductor packaging structures (such as, but not limited to, the technical solution disclosed in invention patent application CN111916408 A) also have some technical defects, mainly their weak temperature uniformity, which negatively affects the service life and reliability of semiconductor packaging structures. Specifically, because the various materials in semiconductor packaging structures have different coefficients of thermal expansion, especially the molding compound which has low thermal conductivity and is not sealed, the product is prone to delamination under long-term thermal stress cycling, thus significantly reducing the service life and reliability of the semiconductor. Summary of the Invention

[0003] The purpose of this invention is to improve the temperature uniformity of semiconductor packaging structures with convenient and economical technical means, thereby overcoming the defects of the prior art.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] A semiconductor packaging structure with temperature equalization function includes a molding compound encapsulation layer, a frame base island, frame pins, metal leads, and a chip. The frame base island consists of an upper shell, a lower shell, a liquid absorber, and powder pillars. The chip is soldered onto the frame base island and connected to the frame pins via metal leads. The frame base island is generally encapsulated in the molding compound encapsulation layer, with the bottom surface of the frame base island and the frame pins exposed outside the molding compound encapsulation layer. Microgrooves are formed on the upper surface of the molding compound encapsulation layer. The upper shell, lower shell, liquid absorber, and powder pillars are fabricated using a temperature equalization plate.

[0006] Based on the above technical solutions, the present invention may employ the following additional technical means to better achieve the objectives of the present invention:

[0007] The molding compound coating layer is made of a filled high thermal conductivity epoxy resin composite material.

[0008] Furthermore, the filled high thermal conductivity epoxy resin composite material is filled with a high thermal conductivity filler, which is an oxide filler and / or a nitride filler.

[0009] Furthermore, the oxide filler is one or more of Al2O3, SiO2, and ZnO, and the nitride filler is one or more of BN, AlN, and Si3N4.

[0010] Furthermore, the volume of the high thermal conductivity filler is 5.9 to 6.1% of the volume of the high thermal conductivity epoxy resin composite material.

[0011] Furthermore, by mass, the high thermal conductivity filler consists of three parts oxide filler and one part nitride filler. In the oxide filler, the mass ratio of Al2O3, SiO2, and ZnO is 3:2:1, and in the nitride filler, the mass ratio of BN, AlN, and Si3N4 is 2:1:1.

[0012] Furthermore, the number of frame pins is three, the lower surface of the chip is reflow soldered onto the upper shell plate, and the upper surface of the chip is connected to the frame pins located on both sides via metal leads.

[0013] Furthermore, the liquid-absorbing core is made of multi-layer wire mesh sintering and assembled together with the powder column.

[0014] Furthermore, the liquid-absorbing core is made of sintered copper powder and is sintered together with the powder column.

[0015] Furthermore, the liquid-absorbing core is sintered together with the upper shell plate.

[0016] The above technical solution constitutes the "product" part of this invention. This invention further provides a corresponding packaging method, which includes the following steps:

[0017] Step 1, Preparation of the frame base island: The upper and lower shell plates are prepared by etching; the liquid wick is prepared by high-temperature sintering of multilayer wire mesh or copper powder; the copper powder is sintered at high temperature to prepare the powder column; the liquid wick is sintered together with the upper shell plate of the frame base island during sintering; the temperature-equalizing plates of the frame base island are assembled and brazed using a mold; liquid working fluid is injected into the steam chamber and vacuum is drawn to obtain the frame base island;

[0018] Step 2, Preparation of filled high thermal conductivity epoxy resin composite material: Using vacuum-assisted self-assembly technology, one or more fillers with high thermal conductivity and excellent insulation properties, such as oxide fillers and / or nitride fillers, are filled into epoxy resin and mixed evenly.

[0019] Step 3, chip bonding: Apply solder to the frame base island, place the chip to be packaged on the solder, and then solder the chip to the upper surface of the upper shell (i.e. the upper surface of the frame base island) by reflow soldering.

[0020] Step 4, lead interconnection: Use metal leads to connect the top of the chip to the frame pins to form a circuit path;

[0021] Step 5, Circuit interconnection test: Ensure the semiconductor devices are working properly through circuit interconnection test (electrical performance test) and reject unqualified products;

[0022] Step 6, Molded Finished Product: The filled high thermal conductivity epoxy resin composite material is placed into the injection molding machine to inject molding material, which encapsulates and protects the chip, frame base island and lead wires, forming a molding material wrapping layer. Microgrooves are formed on the upper surface of the molding material wrapping layer using a mold with microgrooves on its surface.

[0023] Step 7: Remove excess adhesive. This involves using high-pressure water spraying and chemical softening to remove excess adhesive from the surface of the plastic-sealed product, thereby ensuring the product's aesthetic appeal.

[0024] Compared with the prior art, the main beneficial effects of the present invention are as follows:

[0025] The semiconductor packaging structure with temperature equalization function manufactured in this invention is based on the phase transition principle, achieving a thermal conductivity of tens of times higher than that of the original frame base island. It uses a filler with high thermal conductivity and good electrical insulation to fill the molding compound, effectively improving the thermal conductivity of the molding compound. By increasing the heat dissipation area on the upper surface of the molding compound wrapping layer through microgrooves, the heat dissipation capacity of the heat dissipation channel on the upper part of the chip is further improved, effectively reducing the thermal stress of the semiconductor during operation, thereby improving the service life and reliability of the semiconductor. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a longitudinal section structure according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the internal structure of this embodiment;

[0028] Figure 3 This is a schematic diagram of the assembly structure of the upper shell plate in this embodiment.

[0029] In the picture:

[0030] 1—Molding compound coating layer; 101—Microgrooves (on the upper surface of the molding compound coating layer); 2—Upper shell plate; 3—Liquid absorbent core; 4—Chip;

[0031] 5 – Metal lead wire; 6 – Frame pin; 7 – Steam chamber;

[0032] 8—Powder column; 9—Lower shell plate; 10—Frame base island. Detailed Implementation

[0033] To facilitate a thorough understanding of the technical solution of the present invention by those skilled in the art, an embodiment of the present invention will be described below in conjunction with the accompanying drawings.

[0034] like Figure 1 and combined Figure 2 , Figure 3As shown, a semiconductor packaging structure with temperature equalization function includes a molding compound encapsulation layer 1, a frame base island 10, frame pins 6, metal leads 5, and a chip 4. The frame base island 10 is composed of an upper shell plate 2, a lower shell plate 9, a liquid absorbent wick 3, and powder pillars 8 (the liquid absorbent wick 3 and powder pillars 8 are disposed in a sealed space between the upper shell plate 2 and the lower shell plate 9). The chip 4 is soldered onto the frame base island 10 and connected to the frame pins 6 through the metal leads 5. The frame base island 10 is generally encapsulated in the molding compound encapsulation layer 1 (the so-called "generally encapsulated in the molding compound encapsulation layer" refers to the frame...). The top surface and the four sides (front, back, left, and right) of the base island are all covered by a molding compound coating layer. The bottom surface of the frame base island 10 and the frame pins 6 are exposed outside the molding compound coating layer 1. Microgrooves 101 are formed on the upper surface of the molding compound coating layer 1 (in this embodiment, the cross-sectional shape of the microgrooves 101 is "V" shaped, and its function is to increase the heat dissipation area of ​​the upper surface of the molding compound coating layer). The upper shell plate 2, lower shell plate 9, liquid absorber 3, and powder column 8 are made of a heat spreader plate (in this embodiment, a heat spreader plate refers to a hollow flat plate or heat pipe containing liquid under internal vacuum or negative pressure). It should also be noted that the sealed space between the upper shell plate 2 and the lower shell plate 9, excluding the volume occupied by the liquid absorber 3, powder column 8, and liquid working fluid (one or a mixture of deionized water, ethanol, and acetone), is called the vapor chamber 7.

[0035] In this embodiment, the molding compound coating layer 1 is prepared using a filled high thermal conductivity epoxy resin composite material. The high thermal conductivity filler in the filled high thermal conductivity epoxy resin composite material includes oxide fillers and / or nitride fillers. The oxide filler is one or more of Al2O3, SiO2, and ZnO, and the nitride filler is one or more of BN, AlN, and Si3N4. The volume of the high thermal conductivity filler is 5.9-6.1% of the volume of the high thermal conductivity epoxy resin composite material. In a preferred embodiment of the present invention, the high thermal conductivity filler consists of three parts by weight of oxide filler and one part by weight of nitride filler. In the oxide filler, the mass ratio of Al2O3, SiO2, and ZnO is 3:2:1, and in the nitride filler, the mass ratio of BN, AlN, and Si3N4 is 2:1:1.

[0036] like Figure 2 As shown, in this embodiment, there are three frame pins 6. The lower surface of the chip 4 is reflow soldered onto the upper shell plate 2 of the frame base island 10. The upper surface of the chip 4 is connected to the frame pins 6 located on both sides through metal leads 5.

[0037] In this embodiment, the liquid-absorbing core 3 is made of multi-layer wire mesh sintering and assembled with the powder column 8. The liquid-absorbing core 3 can also be made of copper powder sintering and sintered with the powder column 8 (the powder column 8 is also prepared by copper powder sintering and serves as support and liquid reflux between the upper and lower shell plates). In addition, the liquid-absorbing core 3 is also sintered with the upper shell plate 2.

[0038] The structural features of an embodiment of the present invention have been described above with reference to the accompanying drawings. The encapsulation method is further described below, comprising the following steps:

[0039] Step 1, Preparation of the frame base island: The upper and lower shell plates are prepared by etching; the liquid wick is prepared by high-temperature sintering of multilayer wire mesh or copper powder; the copper powder is sintered at high temperature to prepare the powder column; the liquid wick is sintered integrally with the upper shell plate of the frame base island during sintering; the temperature-equalizing plates of the frame base island are assembled and brazed using a mold; a liquid working medium (one or a mixture of deionized water, ethanol, and acetone) is injected into the vapor chamber; and a vacuum is drawn to obtain the frame base island (in short, the frame base island is formed after sealing, liquid filling, and vacuuming).

[0040] Step 2, Preparation of filled high thermal conductivity epoxy resin composite material: Using vacuum-assisted self-assembly technology, one or more fillers with high thermal conductivity and excellent insulation properties, such as oxide fillers and / or nitride fillers, are filled into epoxy resin and mixed evenly.

[0041] Step 3, chip bonding: Apply solder to the frame base island, place the chip to be packaged on the solder, and then solder the chip to the upper surface of the upper shell (i.e. the upper surface of the frame base island) by reflow soldering.

[0042] Step 4, lead interconnection: Use metal leads to connect the top of the chip to the frame pins to form a circuit path;

[0043] Step 5, Circuit interconnection test: Ensure the semiconductor devices are working properly through circuit interconnection test (electrical performance test) and reject unqualified products;

[0044] Step 6, Molded Finished Product: The filled high thermal conductivity epoxy resin composite material is placed into the injection molding machine to inject molding material, which encapsulates and protects the chip, frame base island and lead wires, forming a molding material wrapping layer. Microgrooves are formed on the upper surface of the molding material wrapping layer using a mold with microgrooves on its surface.

[0045] Step 7: Remove excess adhesive. This involves using high-pressure water spraying and chemical softening to remove excess adhesive from the surface of the plastic-sealed product, thereby ensuring the product's aesthetic appeal.

Claims

1. A semiconductor package structure with temperature uniformity function, comprising a plastic encapsulation layer, a frame base island, frame pins, metal leads and a chip; the frame base island is composed of an upper shell plate, a lower shell plate, a wick and a powder column; the chip is welded on the frame base island and connected with the frame pins through the metal leads; the frame base island is generally wrapped in the plastic encapsulation layer, and the bottom surface of the frame base island and the frame pins are exposed outside the plastic encapsulation layer; characterized in that: Microgrooves are formed on the upper surface of the molding compound coating layer; the upper shell plate, lower shell plate, liquid absorbent core, and powder column are prepared using a temperature equalization plate; the molding compound coating layer is prepared using a filled high thermal conductivity epoxy resin composite material; the filled high thermal conductivity epoxy resin composite material is filled with high thermal conductivity filler, which is an oxide filler and a nitride filler; the volume of the high thermal conductivity filler is 5.9-6.1% of the high thermal conductivity epoxy resin composite material; by mass, the high thermal conductivity filler consists of three parts oxide filler and one part nitride filler, in which the mass ratio of Al2O3, SiO2, and ZnO in the oxide filler is 3:2:1, and in which the mass ratio of BN, AlN, and Si3N4 in the nitride filler is 2:1:

1. ​ 2. The semiconductor packaging structure with temperature equalization function as described in claim 1, characterized in that: The chip has three frame pins. The lower surface of the chip is reflow soldered onto the upper shell plate. The upper surface of the chip is connected to the frame pins on both sides via metal leads.

3. The semiconductor packaging structure with temperature equalization function as described in claim 1, characterized in that: The liquid-absorbing core is made of multi-layer wire mesh sintering and assembled with the powder column; or, the liquid-absorbing core is made of copper powder sintering and sintered with the powder column.

4. The semiconductor packaging structure with temperature equalization function as described in any one of claims 1 to 3, characterized in that: The liquid-absorbing core is sintered together with the upper shell plate.

5. A packaging method for a semiconductor packaging structure with temperature equalization function as described in claim 4, characterized in that, Includes the following steps: Step 1, Preparation of the frame base island: The upper and lower shell plates are prepared by etching; the liquid wick is prepared by high-temperature sintering of multilayer wire mesh or copper powder; the copper powder is sintered at high temperature to prepare the powder column; the liquid wick is sintered together with the upper shell plate of the frame base island during sintering; the temperature-equalizing plates of the frame base island are assembled and brazed using a mold; liquid working fluid is injected into the steam chamber and vacuum is drawn to obtain the frame base island; Step 2, Preparation of filled high thermal conductivity epoxy resin composite material: Using vacuum-assisted self-assembly technology, one or more fillers with high thermal conductivity and excellent insulation properties, such as oxide fillers and / or nitride fillers, are filled into epoxy resin and mixed evenly. Step 3, chip bonding: Apply solder to the frame base island, place the chip to be packaged on the solder, and then solder the chip to the upper surface of the upper shell plate by reflow soldering. Step 4, lead interconnection: Use metal leads to connect the top of the chip to the frame pins to form a circuit path; Step 5, Circuit interconnection test: The circuit interconnection test ensures that the semiconductor devices are working properly and rejects unqualified products; Step 6, Molded Finished Product: The filled high thermal conductivity epoxy resin composite material is placed into the injection molding machine to inject molding material, which encapsulates and protects the chip, frame base island and lead wires, forming a molding material wrapping layer. Microgrooves are formed on the upper surface of the molding material wrapping layer using a mold with microgrooves on its surface. Step 7: Remove excess adhesive, which involves using high-pressure water spraying and chemical softening to remove excess adhesive from the surface of the plastic-sealed product.

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