Technological method of novel spraying type filling and sealing structure

Abstract

The invention relates to a process method of a novel spraying type filling and sealing structure. The process method comprises the following steps: step 1, drawing a program graph; 2, cleaning the lead frame; step 3, spraying the front / back surface of the program pattern; step 4, pre-curing; step 5, post-curing; and step 6, packaging the chip. According to the method, a program pattern spraying process method is adopted, other expenses do not need to be spent except that a program pattern needs to be designed and drawn, and the equipment investment cost of a new product or a new technology is greatly reduced.

Description

Technical Field

[0001] The invention relates to a process method for a novel spray-type filling structure, belonging to the technical field of semiconductor packaging. Background Art

[0002] 1. Traditional craft technology: 1.1. The metal lead frame used in traditional chip packaging is a fully hollow design structure (such as Figure 1 As shown in the figure, the conventional method of manufacturing metal lead frames is nothing more than die punching or chemical etching. However, no matter which method is used, the metal lead frames are still completely hollow in shape and structure. 1.2. The pre-molded metal lead frame structure used in traditional LED chip packaging, in addition to using mold punching or chemical etching to form a fully hollow metal lead frame, also adds a pre-molded mold to mold the hollow lead frame for the lamp particle reflector cup. The traditional pre-molded process method uses a fixed mold and then uses thermosetting epoxy resin for transfer potting to form a pre-molded lamp particle reflector cup structure.

[0003] Second, the defects of traditional technology: 2.1 The traditional fully hollow metal lead frame, due to the fully hollow structural design (especially at the base island position), the chip installation structure will be limited to a small chip and large base island structure (such as Figure 2 As shown in the figure, if the chip is a large chip with relatively large functions, it will most likely be larger than the effective size of the base island. This will cause the bonding material (such as conductive glue or non-conductive glue) between the chip and the metal base island to be squeezed out of the metal base island during the chip installation process due to the extrusion relationship of the chip installation, causing the metal base island to have an electrical short circuit with the nearby inner pins or contaminating the metal inner pins (such as Figure 3 , Figure 4 As shown in the figure), it is impossible or difficult to bond the metal wire to the metal inner pin; 2.2 The pre-molded metal lead frame structure used in traditional LED chip packaging requires expensive molding molds and plastic molding compound potting equipment for transfer potting. In addition to the high equipment purchase price, the design and manufacturing cycle of the equipment and molds is as long as 3 to 4 months, wasting time and money; 2.3 The pre-plastic metal lead frame structure used in traditional LED chip packaging has hundreds of chip packaging appearances. Each package size requires a separate dedicated molding die. In addition to spending a lot of time and money, it also requires a lot of space to place molding dies of many different package sizes. 2.4 The pre-molded metal lead frame structure used in traditional LED chip packaging uses a fixed mold for epoxy resin molding compound potting. Due to factors such as foreign matter on the mold surface and exhaust grooves, the molding compound may overflow. This requires a process to remove the overflow, as well as investment and cost in equipment, manpower, materials, space and environmental treatment. 2.5 The pre-molded metal lead frame structure used in traditional LED chip packaging uses a fixed potting mold, so the epoxy resin molding compound cannot control the thickness of the potting. The thickness after potting is the same as the designed thickness of the mold, and the thickness cannot be changed due to different functions or requirements. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a new process method for spray-type filling structure in response to the above-mentioned prior art. The process adopts a commercial or industrial liquid nozzle to perform local spraying at the hollow position of the hollow metal lead frame through program graphics. During the spraying process, a UV lamp is simultaneously used for irradiation to promote the pre-curing of the UV type epoxy resin. After completion, it is then baked at high temperature in an infrared oven to achieve a complete curing effect, which well solves the technical problems existing in the prior art.

[0005] The technical solution adopted by the present invention to solve the above problems is: a process method of a novel spray-type filling structure, the method comprising the following steps: Step 1: Program graphics drawing; Step 2: Cleaning the lead frame; Step 3: Spray the front and back of the program graphics; Step 4: pre-curing; Step 5: Post-curing; Step 6: Chip packaging.

[0006] Optionally, in step 1, draw the graphics and positions to be sprayed on the metal lead frame AutoCAD graphics, complete the AutoCAD file format of the graphics to be coated and then convert it into JPG, PDF or a file format that can be adapted to the spraying equipment.

[0007] Optionally, the lead frame cleaning process in step 2 includes grease removal, rust removal, pure water cleaning, and drying and baking.

[0008] Optionally, in step three, the program graphic spraying equipment is positioned relative to the metal lead frame according to the designed program graphic data.

[0009] Optionally, in step three, the program graphic spraying equipment adopts fixed L-shaped positioning block positioning or visual indiscriminate positioning.

[0010] Optionally, in step three, the program graphics are sprayed through a UV spraying device and UV epoxy resin ink is added, and the spraying is performed at the required spraying positions according to the program graphics.

[0011] Optionally, the graphic spraying material in step three uses epoxy resin ink with added UV chemical material.

[0012] Optionally, in step 4, pre-curing is performed by irradiating a UV lamp to decompose the UV component in the UV epoxy resin, and the epoxy resin film is in a semi-cured, fixed, and non-flowing state.

[0013] Optionally, step 5 post-curing uses high temperature and long-term infrared baking to achieve true permanent curing of the epoxy resin.

[0014] Optionally, the specific process of chip packaging in step 6 includes local spraying of metal lead frame Apply adhesive material Chip bonding Wire bonding Plastic packaging Forming / Separation.

[0015] Compared with the prior art, the advantages of the present invention are: 1. The present invention adopts a program graphic spraying process method. The program graphic spraying equipment used is universal, and can use commercial nozzles or industrial nozzles. Universal program graphic spraying, whether it is full-area spraying, local area spraying or fully hollowed-out metal lead frames of different packaging types and sizes, does not require any other expenses except for the design and drawing of the program graphics, which reduces the equipment investment cost of new products or new technologies by at least 70%; 2. The present invention can completely solve the problems of electrical short circuit or pollution of large chip and small base island because the metal base island and the nearby metal inner pins are sprayed with UV epoxy resin at the hollow position at the same time. Figure 4 shown); 3. Since the present invention adopts program graphics for spraying, only the hollowed-out parts of the metal lead frame that need to be sprayed are sprayed, so the pins and other parts in the metal lead frame are not polluted, and there is no defect of overflow of plastic packaging material at all; 4. The spraying thickness of the present invention can be adjusted with the speed, viscosity, temperature and number of layers of UV epoxy resin spraying to obtain the required thickness; it can be adjusted at will to meet different needs or functions without any cost, just modify the parameter program or graphics; 5. The present invention can spray protruding patterns or retaining walls separately, which has the advantages of increasing the bonding ability with the plastic packaging material, preventing the bonding material from expanding and contaminating the metal wire bonding area, and also increasing the structural strength of the spraying area on the other side; 6. The present invention is more suitable for chip mounting without a base island on a metal lead frame. In addition to conventional chip mounting, it also completely solves the defect of leakage of coated chip adhesive material, and does not need to use an adhesive film (DAF) that is at least 3 times more expensive than a liquid adhesive material. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of a traditional fully hollow metal lead frame.

[0017] Figure 2 Schematic diagram of the chip-small and chip-large island mounting structure.

[0018] Figure 3 Schematic diagram of contamination or electrical short circuit caused by small islands on large chips.

[0019] Figure 4 Schematic diagram of a large chip with a small base island that will not cause contamination or electrical short circuits. DETAILED DESCRIPTION

[0020] The present invention relates to a novel process method for spraying a sealing structure, which comprises the following steps: Step 1: Program graphics drawing; Draw the graphics and positions to be sprayed on the metal lead frame AutoCAD graphics, complete the AutoCAD file format of the graphics to be coated and convert it into JPG, PDF or a file format that can be adapted to the spraying equipment; Step 2: Cleaning the lead frame; The metal lead frame is coated with an antioxidant or film during the packaging process to prevent corrosion or rust on the metal or metal coating surface of the metal lead frame. Therefore, the metal lead frame needs to be cleaned before the program pattern is sprayed. The cleaning process is based on the characteristics of the material, which includes grease removal, rust removal, pure water cleaning, and drying and baking to ensure that the surface of the metal lead frame is clean and increase the bonding ability of the UV epoxy resin and the metal lead frame; Step 3: Spray the front and back of the program graphics; 3.1 Lead frame positioning: According to the program graphic data drawn by the design, the metal lead frame is positioned. The spraying equipment can be positioned by a fixed L-shaped positioning block or by visual indiscriminate positioning (indiscriminate positioning means that there is no need to specify the position, as long as the metal lead frame is placed within the effective scanning area, and then the position is memorized by visual scanning); 3.2 Program graphics spraying: Add UV epoxy resin ink through UV spraying equipment, and spray the required spraying position according to the program graphics; 3.3 Spraying material: Epoxy resin ink with UV chemical materials added, the purpose is to quickly and quickly reach a non-flowing state of initial shaping; 3.4 Spraying thickness: It is determined by the viscosity, temperature, spraying pressure, spraying amount and spraying moving speed of the epoxy resin material matched with the nozzle in the spraying equipment; 3.5 Number of spray layers: The number of spray layers to be added is determined by the spray thickness of each layer and the total thickness required for spraying; Step 4: pre-curing; After the UV epoxy resin material is sprayed on the position where the metal lead frame needs to be sprayed by the UV spraying equipment, the UV lamp is immediately started to irradiate to decompose the UV components in the UV epoxy resin. At this time, the epoxy resin film has already shown a semi-cured fixed and non-flowing state; Step 5: Post-curing; When the epoxy resin is formed into a non-flowing state, it can enter high-temperature and long-term infrared baking to achieve the true permanent curing of the epoxy resin; the baking temperature and time principle are adjusted and set according to the model and characteristics of the material; Step 6: Chip packaging; The chip packaging is carried out by using a metal lead frame that is partially sprayed with program graphics. The chip packaging process does not need to be specially changed and can be implemented completely according to the conventional chip packaging process flow. The specific process is as follows: Partially spray the metal lead frame Apply adhesive material Chip bonding Wire bonding Plastic packaging Forming / separation; Step 7: Quality inspection; The inspection method can be manual visual inspection plus measuring instruments for dimensional inspection, or visual equipment can be used to inspect the relevant dimensions and appearance; Step 8: Packing and storage; Products that have passed quality inspection can be packaged and put into storage. The packaging requirements depend on the relationship between the material and the environment, and can be vacuum packaged in general or after drying.

[0021] In addition to the above embodiments, the present invention also includes other implementation modes. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the protection scope of the claims of the present invention.

Claims

1. A novel process for spray-filling a structure, characterized in that The method comprises the following steps: Step 1: Program graphics drawing; Step 2: Cleaning the lead frame; Step 3: Spray the front and back of the program graphics; Step 4: pre-curing; Step 5: Post-curing; Step 6: Chip packaging.

2. A process method for a novel spray-type sealing structure according to claim 1, characterized in that: Step 1: Draw the graphics and positions that need to be sprayed on the metal lead frame AutoCAD drawing, complete the AutoCAD file format of the graphics that need to be coated and then convert it into JPG, PDF or a file format that can be adapted to the spraying equipment.

3. The process method of a novel spray-filling structure according to claim 1 is characterized in that: The lead frame cleaning process in step 2 includes grease removal, rust removal, pure water cleaning, and drying and baking.

4. A process method for a novel spray-filling structure according to claim 1, characterized in that: Step 3: The program graphic spraying equipment is positioned with the metal lead frame according to the designed program graphic data.

5. A novel spray-type sealing structure process according to claim 4, characterized in that: Step 3: The program graphic spraying equipment adopts fixed L-shaped positioning block positioning or visual indiscriminate positioning.

6. A novel spray-type sealing structure process according to claim 1, characterized in that: Step 3: Program Graphics Spraying: Add UV epoxy resin ink through UV spraying equipment, and spray the required spraying positions according to the program graphics.

7. The process method of a novel spray-filling structure according to claim 1 is characterized in that: Step 3: The program graphic spraying material adopts epoxy resin ink with added UV chemical material.

8. The process method of a novel spray-filling structure according to claim 1 is characterized in that: Step 4: Pre-curing: UV lamp is used to decompose the UV component in the UV epoxy resin. At this time, the epoxy resin film is in a semi-cured, fixed and non-flowing state.

9. The process method of a novel spray-filling structure according to claim 1 is characterized in that: Step 5: Post-curing uses high temperature and long-term infrared baking to achieve true permanent curing of the epoxy resin.

10. The process method of a novel spray-filling structure according to claim 1 is characterized in that: Step 6: Chip packaging: The specific process includes local spraying of metal lead frame Apply adhesive material Chip bonding Wire bonding Plastic packaging Forming / Separation.

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