Semiconductor package structure with uniform temperature enhancement heat dissipation function and packaging method thereof

Abstract

The application provides a semiconductor packaging structure with uniform temperature enhancement heat dissipation function and a packaging method thereof. The semiconductor packaging structure 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 shell plate, the lower shell plate, the liquid absorbing core and the powder column are prepared by using a uniform temperature plate, and a plurality of fins integrally formed with the lower shell plate are arranged on the lower surface of the lower shell plate. The application significantly enhances the uniform temperature and heat dissipation function of the semiconductor packaging structure, thereby effectively improving the reliability, service life and overload capacity of the semiconductor.

Description

Technical Field

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

[0002] Semiconductor molded 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 CN115831887 A) also have some technical defects, mainly weak temperature uniformity and heat dissipation functions. Taking heat dissipation as an example, although existing semiconductor packaging structures use fins (also known as heat sink fins), the fins are mechanically fixed to the back of the frame base island (i.e., not integrally formed with the frame base island). During operation, interfacial thermal resistance and contact thermal resistance are generated, resulting in weakened heat dissipation. The technical defects of weak temperature uniformity and heat dissipation functions have a negative impact on the service life and reliability of semiconductor packaging structures. Specifically, because the various materials in the semiconductor packaging structure 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, thereby 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 and heat dissipation function 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 heat dissipation enhancement and temperature equalization function includes a molding compound encapsulation layer, a frame base island, frame pins, metal leads, and a chip. The frame base island is composed 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. The upper shell, lower shell, liquid absorber, and powder pillars are fabricated using a heat spreader, and multiple fins integrally formed with the lower shell are disposed on the lower surface of the lower shell.

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

[0007] The multiple fins are parallel to each other and perpendicular to the lower shell plate.

[0008] Furthermore, the molding compound coating layer is prepared using a filled high thermal conductivity epoxy resin composite material, which 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; or, the liquid-absorbing core is made of copper powder sintering and sintered together with the powder column.

[0014] Furthermore, the liquid-absorbing core is sintered together with the upper shell plate.

[0015] The above technical solution constitutes the "product" part of this invention. This invention further provides a corresponding packaging method, which includes the following steps:

[0016] Step 1, Preparation of frame base island fins: Columnar fins are prepared on the lower surface of the lower shell of the frame base island by extrusion or etching.

[0017] Step 2, Preparation of the frame base island: The upper and lower shell plates of the frame base island are prepared by etching; multi-layer wire mesh with pre-drilled holes is sintered onto the upper and lower shell plates using a mold; copper powder is sintered into the corresponding holes in the upper shell plate to form powder columns using a mold; the upper and lower shell plates are brazed through a mold, liquid working fluid is injected and vacuum is drawn to obtain a frame base island integrating fins and a heat spreader.

[0018] Step 3, 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 4: 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.

[0020] Step 5, lead interconnection: Use metal leads to connect the top of the chip to the frame pins to form a circuit path;

[0021] Step 6, Circuit interconnection test: The circuit interconnection test ensures that the semiconductor devices are working properly and rejects unqualified products;

[0022] Step 7: Place the filled high thermal conductivity epoxy resin composite material into the injection molding machine, inject the molding compound, and encapsulate and protect the chip, frame base island and lead wires to form a molding compound encapsulation layer;

[0023] Step 8, Remove excess glue: Use high-pressure water spray and chemical softening to remove excess glue.

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

[0025] In this invention, the frame base island integrates fins and a heat spreader. Based on the phase change principle, the heat spreader can quickly diffuse the heat generated during chip operation throughout the entire frame base island, and dissipate it through the connected fins. This eliminates the interface and contact thermal resistance caused by mechanically fixing external fins, significantly improving the heat dissipation capacity of the main heat dissipation channel in the semiconductor packaging structure. Furthermore, the upper surface of the chip is filled with a molding compound that has high thermal conductivity and good electrical insulation, effectively improving the heat dissipation capacity of the heat dissipation channel on the upper part of the chip, thereby effectively improving the reliability, lifespan, and overload capacity 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] Figure 4 This is a schematic diagram of the liquid-absorbing core in this embodiment.

[0030] In the picture:

[0031] 1—Frame pin; 2—Metal lead; 3—Chip;

[0032] 4 – Top shell plate; 5 – Plastic sealant layer; 6 – Liquid absorbent core;

[0033] 7 – Steam chamber; 8 – Powder column; 9 – Fin;

[0034] 10 – Lower shell plate; 11 – Frame base island Detailed Implementation

[0035] 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.

[0036] like Figures 1 to 4 As shown, a semiconductor packaging structure with uniform temperature and enhanced heat dissipation function includes a molding compound encapsulation layer 5, a frame base island 11, frame pins 1, metal leads 2, and a chip 3; the frame base island 11 is composed of an upper shell plate 4, a lower shell plate 10, a liquid absorbent wick 6, and powder pillars 8 (the liquid absorbent wick 6 and powder pillars 8 are disposed in a sealed space between the upper shell plate 4 and the lower shell plate 10); the chip 3 is soldered onto the frame base island 11 and connected to the frame pins 1 via the metal leads 2; the frame base island 11... The frame base island 11 is generally encapsulated in a molding compound layer 5 (meaning that the top surface and the four sides (front, back, left, and right) of the frame base island are all encapsulated in the molding compound layer), while the bottom surface of the frame base island 11 and the frame pins 1 are exposed outside the molding compound layer 5. The upper shell plate 4, lower shell plate 10, liquid absorber 3, and powder column 8 are made of a vapor chamber. Multiple fins 9 integrally formed with the lower shell plate 10 are provided on the lower surface of the lower shell plate 10. The fins 9 are also called heat dissipation fins, and their specific number can be adjusted according to the size of the semiconductor packaging structure and actual needs. In this invention, a vapor chamber refers to a hollow flat plate or heat pipe containing liquid under internal vacuum or negative pressure. In addition, the sealed space between the upper shell plate 4 and the lower shell plate 10, excluding the volume occupied by the liquid absorber 6, powder column 8, and liquid working fluid (one or a mixture of deionized water, ethanol, and acetone), is called the vapor chamber 7.

[0037] In this embodiment, multiple fins 9 are parallel to each other and perpendicular to the lower shell plate 10. The molding compound coating layer 5 is prepared using a filled high thermal conductivity epoxy resin composite material, which is filled with a high thermal conductivity filler, which is an oxide filler and / or a nitride filler. 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 high thermal conductivity epoxy resin composite material. As 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.

[0038] like Figure 2As shown, in this embodiment, there are three frame pins 1. The lower surface of the chip 3 is reflow soldered onto the upper shell plate 4 of the frame base island 11. The upper surface of the chip 3 is connected to the frame pins 1 located on both sides through metal leads 2.

[0039] like Figure 4 As shown, in this embodiment, the liquid-absorbing core 6 is made of multi-layer wire mesh sintering (some people also refer to the liquid-absorbing core as the liquid-absorbing core layer) and is assembled with the powder column 8; the liquid-absorbing core 6 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 it plays a supporting role and liquid reflux between the upper and lower shell plates). In addition, the liquid-absorbing core 6 is also sintered with the upper shell plate 4.

[0040] The structural features of one embodiment of the present invention have been described above with reference to the accompanying drawings. The encapsulation method is further described below, which includes the following steps:

[0041] Step 1, Preparation of frame base island fins: Columnar fins are prepared on the lower surface of the lower shell of the frame base island by extrusion or etching.

[0042] Step 2, Preparation of the frame base island: The upper and lower shell plates of the frame base island are prepared by etching; multi-layer wire mesh with pre-drilled holes is sintered onto the upper and lower shell plates using a mold; copper powder is sintered into the corresponding holes in the upper shell plate using a mold to form powder columns; the upper and lower shell plates are brazed through a mold, liquid working fluid is injected and vacuum is drawn to obtain the frame base island integrating fins and heat spreader (in short, the frame base island is formed after sealing, liquid filling and vacuuming).

[0043] Step 3, 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.

[0044] Step 4: 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.

[0045] Step 5, lead interconnection: Use metal leads to connect the top of the chip to the frame pins to form a circuit path;

[0046] Step 6, Circuit interconnection test: The circuit interconnection test ensures that the semiconductor devices are working properly and rejects unqualified products;

[0047] Step 7: Place the filled high thermal conductivity epoxy resin composite material into the injection molding machine, inject the molding compound, and encapsulate and protect the chip, frame base island and lead wires to form a molding compound encapsulation layer;

[0048] Step 8, Remove excess glue: Use high-pressure water spray and chemical softening to remove excess glue.

Claims

1. A semiconductor packaging structure with temperature uniformity and enhanced heat dissipation function, comprising a molding compound encapsulation layer, a frame base island, frame pins, metal leads, and a chip; the frame base island is composed of an upper shell, a lower shell, a liquid absorbent wick, 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; characterized in that: The upper shell plate, lower shell plate, liquid suction core and powder column are made of a temperature equalization plate, and multiple fins integrally formed with the lower shell plate are provided on the lower surface of the lower shell plate. The molding compound coating layer is made of a filled high thermal conductivity epoxy resin composite material, which is filled with high thermal conductivity fillers, namely oxide fillers and nitride fillers. 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; 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.

2. The semiconductor packaging structure with temperature uniformity and enhanced heat dissipation function as described in claim 1, characterized in that: The multiple fins are parallel to each other and perpendicular to the lower shell plate.

3. The semiconductor packaging structure with temperature uniformity and enhanced heat dissipation 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.

4. The semiconductor packaging structure with temperature uniformity and enhanced heat dissipation 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.

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

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