High-performance high-voltage high-current MOS tube packaging process

Abstract

The present application belongs to the technical field of electronic packaging. More particularly, it relates to a high-performance high-voltage large-current MOS tube packaging process. The specific packaging steps of the present application include: scribing: cutting and separating the chips distributed in a matrix on a wafer into independent single chips; coating nano-silver paste: coating nano-silver paste between the chips and the pretreated DFN frame substrate; curing: curing the nano-silver paste by heat treatment to form an electrical connection; wherein the pretreatment steps of the pretreated DFN frame substrate include: coating the surface of the DFN frame substrate facing the nano-silver paste with 1# heat-conducting epoxy resin paint, and then heating and curing to form a thin film heat-conducting coating; then, on the surface of the thin film heat-conducting coating, 2# heat-conducting epoxy resin paint is gravure printed, and then heated and cured to form an island-shaped heat-conducting coating on the surface of the thin film heat-conducting coating.

Description

Technical Field

[0001] The present invention belongs to the field of electronic packaging technology, and more specifically, relates to a high-performance, high-voltage, high-current MOS tube packaging process. Background Art

[0002] For the packaging of high-performance, high-voltage, and high-current MOS tubes, the use of a DFN frame for basic packaging can accelerate the heat dissipation process.

[0003] However, during long-term storage or transportation, impurities such as dust, oil, and oxides may accumulate on the surface of the package frame. If these impurities are not removed, they will affect the product's heat dissipation. Specifically, impurities such as dust and oil can hinder heat transfer, acting as thermal insulators and causing localized temperature increases. This can affect the heat dissipation of the MOS transistor, reducing its performance and reliability. For example, poor heat dissipation can cause the MOS transistor to overheat during high-power operation, thereby reducing its switching speed and conduction performance. Furthermore, oxide impurities can chemically react with the substrate material, altering its properties or causing corrosion. For example, the oxide layer can react with components in the silver paste, affecting its adhesion. Organic matter in the oil can decompose at high temperatures, creating pores or defects, affecting the reliability of the package. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: when MOSFETs are packaged using a DFN frame substrate, the dust, oil and oxides remaining on the surface of the DFN frame substrate easily cause the above-mentioned problems. The present invention provides a high-efficiency, high-voltage and high-current MOSFET packaging process.

[0005] The purpose of the present invention is to provide a high-efficiency, high-voltage, high-current MOS tube packaging process.

[0006] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0007] A high-performance, high-voltage, high-current MOS tube packaging process, the specific packaging steps include:

[0008] Dicing: Cutting and separating the chips distributed in a matrix on the wafer into independent single chips;

[0009] Applying nano silver paste: Applying nano silver paste between the chip and the pre-treated DFN frame substrate;

[0010] Curing: Curing the nano silver paste through heat treatment to form an electrical connection;

[0011] The pre-processing step of pre-processing the DFN frame substrate includes:

[0012] After coating the surface of the DFN frame substrate facing the nano silver paste with 1# thermal conductive epoxy resin coating, heating and curing it to form a thin film thermal conductive coating;

[0013] Then, a 2# thermal conductive epoxy resin coating is gravure-printed on the surface of the thin film thermal conductive coating, and then heated and cured to form an island-shaped thermal conductive coating on the surface of the thin film thermal conductive coating.

[0014] Beneficial effects of the above technical solution:

[0015] The above technical solution adopts DNF frame substrate for packaging. This packaging method reduces the heat conduction path through pinless design, so that heat can be directly transferred from the chip to the substrate, and then transferred to the outside through the substrate, thereby effectively improving the heat dissipation efficiency. Compared with the conventional packaging form, the internal temperature of the chip can be reduced; however, the inventor found in the actual research process that the surface of the DNF substrate facing the chip is easily oxidized during storage, thereby forming an oxide layer. The presence of the oxide layer easily leads to a decrease in thermal conductivity, and the presence of the oxide layer can also weaken the bonding force between it and the nano silver paste, thereby causing local desorption during long-term use of the product, thereby affecting the heat dissipation capacity; and in order to avoid the appearance of the oxide layer, methods such as surface coating with anti-rust liquid and a pre-treatment process of pickling can be used before use. However, after the anti-rust liquid is applied, it is easy to cause bubbles to appear during the heating and curing process of the nano silver paste, or affect the interface bonding strength between the two, and pickling easily damages the product surface, and the process is difficult to control;

[0016] In view of the existence of the above problems, the present invention first forms a thin film thermal conductive coating on the surface of the frame substrate. On the one hand, it is used to protect the surface of the DFN frame substrate and prevent the formation of an oxide layer on its surface during long-term storage. In addition, it forms a continuous thermal conductive interface on the surface, which is conducive to the uniform distribution of heat in the surface direction. On this basis, an island-shaped thermal conductive coating is further formed on the surface of the thin film thermal conductive coating. The island-shaped structure can extend into the nano-silver paste during the curing process of the nano-silver paste and serve as an anchor point to enhance the bonding strength between the nano-silver paste and the thermal conductive coating after curing. In addition, during the curing process of the nano-silver paste, the shrinkage stress generated can be transferred to the thin film thermal conductive coating through the island-shaped thermal conductive coating to achieve stress release. At the same time, since both the island-shaped thermal conductive coating and the thin film thermal conductive coating use epoxy resin as the coating, the bonding strength between the two is strong, and the island area and the substrate will not fall off due to the transfer of shrinkage stress. More importantly, the presence of the island-shaped coating can avoid the problem of bubble formation at the interface due to the generation of shrinkage stress during the curing process of the nano-silver paste. Due to the reduction of bubbles, the integrity of the thermal conductive interface is improved.

[0017] Furthermore, the thickness of the thin film thermal conductive coating is 8-12 μm.

[0018] Furthermore, the 1# thermal conductive epoxy resin coating includes the following raw materials in parts by weight: 100-110 parts of epoxy resin E44, 10-12 parts of amine curing agent, 15-20 parts of monodisperse graphene oxide, 2-4 parts of microcrystalline wax, and 0.3-0.5 parts of polysiloxane defoaming agent.

[0019] Furthermore, the amine curing agent is selected from any one of ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, m-phenylenediamine, p-phenylenediamine, and isophoronediamine.

[0020] Furthermore, the particle size distribution range of the monodisperse graphene oxide is 90-110 nm.

[0021] By using monodisperse graphene oxide as the main thermally conductive filler and supplementing the system with a certain amount of microcrystalline wax, graphene oxide as a layered thermally conductive filler will be beneficial to the uniform transfer of heat in the surface direction of the thin film thermal conductive layer, and the presence of microcrystalline wax can facilitate the diffusion and penetration of graphene oxide into the surface of the thin film thermal conductive layer during the epoxy resin curing process, thereby forming a more complete thermal conductive interface on the surface. In addition, thanks to the rich functional groups of graphene oxide, the bonding strength between the island-shaped thermal conductive coating and the thin film thermal conductive layer will be improved to prevent it from falling off. Moreover, the rich functional groups will also be beneficial to the wetting and spreading of the nano silver paste on the surface during the heating and curing process, reducing the presence of bubbles.

[0022] Furthermore, the island-shaped thermal conductive coating comprises island-shaped protrusions distributed at intervals, and the distribution density of the island-shaped protrusions is 18-20 / cm 2 ; Moreover, the particle height of a single island-shaped protrusion is 20-30 μm.

[0023] Furthermore, the 2# thermal conductive epoxy resin coating includes the following raw materials in parts by weight: 100-110 parts of epoxy resin E44, 10-12 parts of amine curing agent, 20-25 parts of monodisperse spherical nano-alumina, 4-6 parts of microcrystalline wax, and 0.3-0.5 parts of polysiloxane defoaming agent.

[0024] Furthermore, the particle size distribution range of the monodisperse spherical nano-alumina is 80-120 nm;

[0025] The sphericity of the monodisperse spherical nano-alumina is 0.88-0.92.

[0026] By using monodisperse spherical nano-alumina as the thermal conductive filler in the island-shaped thermal conductive coating, the higher sphericity can facilitate more uniform heat transfer in all directions within the system, and the monodisperse particles will make the thermal conductivity between different parts tend to be consistent.

[0027] Further, the monodisperse spherical nano-aluminum oxide is coated with a silane coupling agent on the surface.

[0028] The silane coupling agent is selected from any one of silane coupling agent KH-540, silane coupling agent KH-550, silane coupling agent KH-560, silane coupling agent KH-570, and silane coupling agent KH-580. DETAILED DESCRIPTION

[0029] The application will be further described in conjunction with specific embodiments, but the embodiments do not limit the application in any form. Unless otherwise specified, the reagents, methods, and equipment used in the application are conventional reagents, methods, and equipment in the technical field.

[0030] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0031] Example 1

[0032] A DFN substrate made of copper material is used, with a size specification of 2x3mm;

[0033] Pre-treatment of the DFN substrate:

[0034] The surface of the DFN frame substrate facing the nano-silver paste is coated with 1# heat-conducting epoxy resin paint, and then heated and cured to form a thin film heat-conducting coating with a thickness of 8μm;

[0035] The 1# heat-conducting epoxy resin paint includes the following raw materials in parts by weight: 100 parts of epoxy resin E44, 10 parts of amine curing agent, 15 parts of monodisperse graphene oxide, 2 parts of microcrystalline wax, and 0.3 parts of polysiloxane defoaming agent;

[0036] The amine curing agent is selected from ethylenediamine;

[0037] The particle size distribution range of the monodisperse graphene oxide is 90-110nm;

[0038] Then, 2# heat-conducting epoxy resin paint is gravure printed on the surface of the thin film heat-conducting coating, and then heated and cured to form an island-shaped heat-conducting coating on the surface of the thin film heat-conducting coating, the island-shaped heat-conducting coating is an island-shaped protrusion distributed at intervals, and the distribution density of the island-shaped protrusion is 18 / cm 2 ; and the particle height of a single island-shaped protrusion is 20μm;

[0039] The 2# heat-conducting epoxy resin paint includes the following raw materials in parts by weight: 100 parts of epoxy resin E44, 10 parts of amine curing agent, 20 parts of monodisperse spherical nano-aluminum oxide, 4 parts of microcrystalline wax, and 0.3 parts of polysiloxane defoaming agent;

[0040] The particle size distribution range of the monodisperse spherical nano-aluminum oxide is 80-120nm;

[0041] The sphericity of the monodisperse spherical nano-alumina is 0.88;

[0042] The surface of the monodisperse spherical nano-alumina is coated with a silane coupling agent;

[0043] The silane coupling agent is selected from: silane coupling agent KH-540;

[0044] Dicing:

[0045] Laser cutting is used to separate the chips distributed in a matrix on the wafer into independent single chips;

[0046] Applying nano silver paste:

[0047] Apply nano silver paste between the chip and the pre-treated DFN frame substrate, and control the coating thickness of the nano silver paste to be 40 μm;

[0048] Curing: Curing the nano silver paste through heat treatment to form an electrical connection;

[0049] Bonding: Connect the bonding area on the chip to the lead frame through bonding aluminum wire / gold wire, thereby realizing the connection between the internal functions of the chip and the external circuit;

[0050] Plastic encapsulation: The bonded lead frame is encapsulated with plastic encapsulation material to protect the high-density integrated circuit components;

[0051] Tinning: The solder forms a continuous metal path so that the current can pass smoothly;

[0052] Cutting: Cut the entire strip (whole board) of product after packaging into individual products to facilitate the flow of individual products in subsequent processes.

[0053] Example 2

[0054] The DFN substrate is made of copper and has a size of 2×3mm;

[0055] Pretreatment of DFN substrate:

[0056] After coating the surface of the DFN frame substrate facing the nano silver paste with 1# thermal conductive epoxy resin coating, heat and cure it to form a thin film thermal conductive coating with a thickness of 10 μm;

[0057] The thermal conductive epoxy resin coating No. 1 comprises the following raw materials in parts by weight: 105 parts of epoxy resin E44, 11 parts of amine curing agent, 18 parts of monodisperse graphene oxide, 3 parts of microcrystalline wax, and 0.4 parts of polysiloxane defoaming agent;

[0058] The amine curing agent is selected from diethylenetriamine;

[0059] The particle size distribution range of the monodisperse graphene oxide is 90-110 nm;

[0060] Then, 2# thermal conductive epoxy resin coating is gravure-printed on the surface of the thin film thermal conductive coating, and then heated and cured to form an island-shaped thermal conductive coating on the surface of the thin film thermal conductive coating. The island-shaped thermal conductive coating is an island-shaped protrusion distributed at intervals, and the distribution density of the island-shaped protrusion is 19 / cm 2 ; Moreover, the particle height of a single island-shaped protrusion is 25 μm;

[0061] The 2# thermal conductive epoxy resin coating comprises the following raw materials in parts by weight: 105 parts of epoxy resin E44, 11 parts of amine curing agent, 22 parts of monodisperse spherical nano-alumina, 5 parts of microcrystalline wax, and 0.4 parts of polysiloxane defoaming agent;

[0062] The particle size distribution range of the monodisperse spherical nano-alumina is 80-120 nm;

[0063] The sphericity of the monodisperse spherical nano-alumina is 0.9;

[0064] The surface of the monodisperse spherical nano-alumina is coated with a silane coupling agent;

[0065] The silane coupling agent is selected from: silane coupling agent KH-550;

[0066] Dicing:

[0067] Laser cutting is used to separate the chips distributed in a matrix on the wafer into independent single chips;

[0068] Applying nano silver paste:

[0069] Apply nano silver paste between the chip and the pre-treated DFN frame substrate, and control the coating thickness of the nano silver paste to be 50 μm;

[0070] Curing: Curing the nano silver paste through heat treatment to form an electrical connection;

[0071] Bonding: Connect the bonding area on the chip to the lead frame through bonding aluminum wire / gold wire, thereby realizing the connection between the internal functions of the chip and the external circuit;

[0072] Plastic encapsulation: The bonded lead frame is encapsulated with plastic encapsulation material to protect the high-density integrated circuit components;

[0073] Tinning: The solder forms a continuous metal path so that the current can pass smoothly;

[0074] Cutting: Cut the entire strip (whole board) of product after packaging into individual products to facilitate the flow of individual products in subsequent processes.

[0075] Example 3

[0076] The DFN substrate is made of copper and has a size of 2×3mm;

[0077] Pretreatment of DFN substrate:

[0078] After coating the surface of the DFN frame substrate facing the nano silver paste with 1# thermal conductive epoxy resin coating, heat and cure it to form a thin film thermal conductive coating with a thickness of 12 μm;

[0079] The thermal conductive epoxy resin coating No. 1 comprises the following raw materials in parts by weight: 110 parts of epoxy resin E44, 12 parts of amine curing agent, 20 parts of monodisperse graphene oxide, 4 parts of microcrystalline wax, and 0.5 parts of polysiloxane defoaming agent;

[0080] The amine curing agent is selected from triethylenetetramine;

[0081] The particle size distribution range of the monodisperse graphene oxide is 90-110 nm;

[0082] Then, 2# thermal conductive epoxy resin coating is gravure-printed on the surface of the thin film thermal conductive coating, and then heated and cured to form an island-shaped thermal conductive coating on the surface of the thin film thermal conductive coating. The island-shaped thermal conductive coating is an island-shaped protrusion distributed at intervals, and the distribution density of the island-shaped protrusion is 20 / cm 2 ; Moreover, the particle height of a single island-shaped protrusion is 30 μm;

[0083] The 2# thermal conductive epoxy resin coating comprises the following raw materials in parts by weight: 110 parts of epoxy resin E44, 12 parts of amine curing agent, 25 parts of monodisperse spherical nano-alumina, 6 parts of microcrystalline wax, and 0.5 parts of polysiloxane defoaming agent;

[0084] The particle size distribution range of the monodisperse spherical nano-alumina is 80-120 nm;

[0085] The sphericity of the monodisperse spherical nano-alumina is 0.92;

[0086] The surface of the monodisperse spherical nano-alumina is coated with a silane coupling agent;

[0087] The silane coupling agent is selected from: silane coupling agent KH-560;

[0088] Dicing:

[0089] Laser cutting is used to separate the chips distributed in a matrix on the wafer into independent single chips;

[0090] Applying nano silver paste:

[0091] Apply the nano silver paste between the chip and the pre-treated DFN frame substrate, and control the coating thickness of the nano silver paste to be 60 μm;

[0092] Curing: Curing the nano silver paste through heat treatment to form an electrical connection;

[0093] Bonding: Connect the bonding area on the chip to the lead frame through bonding aluminum wire / gold wire, thereby realizing the connection between the internal functions of the chip and the external circuit;

[0094] Plastic encapsulation: The bonded lead frame is encapsulated with plastic encapsulation material to protect the high-density integrated circuit components;

[0095] Tinning: The solder forms a continuous metal path so that the current can pass smoothly;

[0096] Cutting: Cut the entire strip (whole board) of product after packaging into individual products to facilitate the flow of individual products in subsequent processes.

[0097] Example 4

[0098] Compared with Example 1, this embodiment differs in that:

[0099] The particle size distribution of graphene oxide ranges from 60 to 120 nm, and the other conditions remain unchanged.

[0100] Example 5

[0101] Compared with Example 1, this embodiment differs in that:

[0102] The sphericity of the monodisperse spherical nano-alumina is 0.8, and the other conditions remain unchanged.

[0103] Example 6

[0104] Compared with Example 1, this embodiment differs in that:

[0105] The particle height of a single island-shaped protrusion is 16 μm, and the other conditions remain unchanged.

[0106] Comparative Example 1

[0107] The difference between this comparative example and Example 1 is that the DFN substrate is used directly without pretreatment, and the other conditions remain unchanged.

[0108] Comparative Example 2

[0109] The difference between this comparative example and Example 1 is that the pretreatment method of the DFN substrate is different. Specifically, the pretreatment method of this comparative example is:

[0110] The DFN frame substrate was cleaned three times with an 8% by mass baking soda solution to remove surface oil stains, then cleaned twice with a 10% by mass sulfuric acid solution to remove the surface oxide layer, and then rinsed twice with clean water;

[0111] The rest of the conditions remain unchanged.

[0112] Comparative Example 3

[0113] The difference between this comparative example and Example 1 is that the island-shaped thermal conductive coating is not applied, and the other conditions remain unchanged.

[0114] The performance tests of the products obtained in the examples and comparative examples were carried out, and the specific test methods and test results are as follows:

[0115] The products obtained in the above embodiments or comparative examples were respectively mounted and fixed on a PCB board, and then installed in a circuit loop. Under an ambient temperature of 25°C, a current of 10 mA was applied to the device. After it was allowed to operate continuously under this condition for 4 hours or 45 days, it was stopped and the time required for it to cool down to room temperature (25°C) was measured. The detailed test results are shown in Table 1.

[0116]

[0117] From the test results in Table 1, it can be seen that the product obtained by the present invention can effectively improve the thermal conductivity of the MOS tube after packaging, so that the heat generated by the MOS tube during operation can be quickly dissipated, and the relevant thermal conductivity can still be effectively maintained after long-term continuous operation.

[0118] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A high-performance, high-voltage, high-current MOS tube packaging process, characterized in that: The specific packaging steps include: Dicing: Cutting and separating the chips distributed in a matrix on the wafer into independent single chips; Applying nano silver paste: Applying nano silver paste between the chip and the pre-treated DFN frame substrate; Curing: Curing the nano silver paste through heat treatment to form an electrical connection; The pre-processing step of pre-processing the DFN frame substrate includes: After coating the surface of the DFN frame substrate facing the nano silver paste with 1# thermal conductive epoxy resin coating, heating and curing it to form a thin film thermal conductive coating; The thermal conductive epoxy resin coating No. 1 comprises the following raw materials in parts by weight: 100-110 parts of epoxy resin E44, 10-12 parts of amine curing agent, 15-20 parts of monodisperse graphene oxide, 2-4 parts of microcrystalline wax, and 0.3-0.5 parts of polysiloxane defoaming agent; Then, after gravure printing 2# thermal conductive epoxy resin coating on the surface of the thin film thermal conductive coating, heat and cure it to form an island-shaped thermal conductive coating on the surface of the thin film thermal conductive coating; The 2# thermal conductive epoxy resin coating comprises the following raw materials in parts by weight: 100-110 parts of epoxy resin E44, 10-12 parts of amine curing agent, 20-25 parts of monodisperse spherical nano-alumina, 4-6 parts of microcrystalline wax, and 0.3-0.5 parts of polysiloxane defoaming agent.

2. A high-performance, high-voltage, high-current MOS tube packaging process according to claim 1, characterized in that: The thickness of the thin film thermal conductive coating is 8-12 μm.

3. The high-performance, high-voltage, high-current MOS tube packaging process according to claim 1, characterized in that: The amine curing agent is selected from any one of ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, m-phenylenediamine, p-phenylenediamine and isophoronediamine.

4. The high-performance, high-voltage, high-current MOS tube packaging process according to claim 1, characterized in that: The particle size distribution range of the monodisperse graphene oxide is 90-110 nm.

5. A high-performance, high-voltage, high-current MOS tube packaging process according to any one of claims 1 or 2, characterized in that: The island-shaped thermal conductive coating comprises island-shaped protrusions distributed at intervals, and the distribution density of the island-shaped protrusions is 18-20 / cm 2 ; Moreover, the particle height of a single island-shaped protrusion is 20-30 μm.

6. The high-performance, high-voltage, high-current MOS tube packaging process according to claim 1, characterized in that: The particle size distribution range of the monodisperse spherical nano-alumina is 80-120 nm; The sphericity of the monodisperse spherical nano-alumina is 0.88-0.

92.

7. The high-performance, high-voltage, high-current MOS tube packaging process according to claim 6, characterized in that: The surface of the monodisperse spherical nano-alumina is coated with a silane coupling agent; The silane coupling agent is selected from any one of silane coupling agent KH-540, silane coupling agent KH-550, silane coupling agent KH-560, silane coupling agent KH-570, and silane coupling agent KH-580.

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