Integrated circuit packaging method capable of wetting side wings

Abstract

The invention discloses an integrated circuit packaging method capable of wetting side wings, which belongs to the field of integrated circuit packaging, and comprises the following steps of: 1, preparing a product, and carrying out plastic packaging operation on the product; 2, a groove body is formed in the pin of the product through laser drilling, the laser drilling hole can be formed through laser cold machining of a high-frequency laser, and the side face of the groove body is in an arc shape; step 3, electroplating the surface of the pin to form a plating layer; and fourthly, the product is cut into single pieces. The arc-shaped grooves are formed in the product pins through picosecond / femtosecond high-frequency laser cold machining, the side face area of the pins is increased, side face tin climbing is better facilitated, the welding reliability is improved, meanwhile, materials are removed in a physical sublimation mode in laser machining, inert gas protection is combined, heat residues, melting and high temperature are almost avoided, and the welding quality is improved. Oxidation is fundamentally avoided, additional pre-plating etching and deplating processes are not needed, the clean surface can be obtained, and the process is simplified.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of integrated circuit packaging, and particularly relates to an integrated circuit packaging method with wettable flanks. BACKGROUND

[0002] In the field of integrated circuit packaging, QFN (Quad Flat No-lead) packaging is widely used due to its advantages such as miniaturization and high integration, but the traditional QFN packaging process has significant technical pain points: after the product is molded and cut into single pieces, the side of the pin is a bare copper plane formed by cutting, which is easily oxidized without plating layer protection, and cannot form a wettable flank structure.

[0003] This defect directly leads to two problems: first, in the subsequent SMT (Surface Mount Technology) process, the pin can only be connected by the top surface, and the side cannot be tinned to form additional solder joints, reducing the soldering reliability; second, the lack of wettable side structure makes it difficult to effectively detect the soldering quality through AOI (Automatic Optical Inspection), increasing the difficulty of process yield control. SUMMARY

[0004] In view of the above situation, in order to overcome the defects of the prior art, the application provides an integrated circuit packaging method with wettable flanks, which effectively solves the problem that the side of the pin of the product of the traditional QFN packaging on the market is easily oxidized without plating layer protection after the product is cut into single pieces, and therefore cannot form a wettable flank side, providing better additional side tin connection for subsequent SMT and corresponding AOI detection.

[0005] The technical scheme adopted by the application is as follows: the application provides an integrated circuit packaging method with wettable flanks, comprising the following steps: step 1: preparing a product and performing a molding operation on the product; Step 2: forming a groove on the pin of the product by laser drilling, the laser drilling can be formed by a high-frequency laser cold machining, and the side surface shape of the groove is arc-shaped; Step 3: performing an electroplating operation on the pin surface to form a plating layer; Step 4: performing a single-piece cutting process on the product.

[0006] Preferably, the depth of the groove ranges from 0 to 90% of the thickness of the pin.

[0007] Preferably, the depth of the groove ranges from 1 / 3 to 2 / 3 of the thickness of the pin.

[0008] Preferably, the width of the groove is greater than or equal to the width of the adjacent two pins, and the maximum difference is pi r-2r approximately equal to 1.14r, where r is the laser spot radius.

[0009] Preferably, the laser focus area on the groove body is the width of the groove body, which is the circular arc length between the two points of intersection of the pin and the laser spot.

[0010] Preferably, the high-frequency laser cold working emits laser to form a laser spot at a vertical angle or an offset angle of 45-70° along the Z-axis direction.

[0011] Preferably, in step two, the groove body is covered with a nozzle along the Z-axis or side blowing inert gas to physically isolate oxygen.

[0012] Preferably, the plating layer is a tin plating layer or other metal layer.

[0013] Preferably, the product surface is provided with a plastic encapsulation layer, the product includes a pin, and the pin is provided with a groove body, and the groove body is provided with a plating layer.

[0014] The beneficial effects achieved by the above structure are as follows: the present scheme proposes an integrated circuit packaging method with wettable flanks, which is implemented on the entire product after plastic encapsulation, uses laser drilling process to form wettable flanks, uses picosecond / femtosecond high-frequency laser for cold working, and the material is removed by direct sublimation instead of melting and then gasification, which almost has no excess heat remaining to the surrounding material, has no melting and continuous high temperature, and the conditions for violent reaction with oxygen are fundamentally eliminated, a coaxial or side blowing nozzle is covered on the laser focus area to physically isolate oxygen, and a clean surface with almost no oxidation can be obtained under effective gas protection, compared with the half-cut scheme used in the industry, no complex additional pre-plating etching and de-plating process is needed. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 FIG. 1 is a step one schematic diagram of the integrated circuit packaging method with wettable flanks proposed by the present scheme; Figure 2 FIG. 2 is a step two schematic diagram of the integrated circuit packaging method with wettable flanks proposed by the present scheme; Figure 3 FIG. 3 is a step three schematic diagram of the integrated circuit packaging method with wettable flanks proposed by the present scheme; Figure 4 FIG. 4 is a step four schematic diagram of the integrated circuit packaging method with wettable flanks proposed by the present scheme; Figure 5 FIG. 5 is a strip product slotting schematic diagram of the integrated circuit packaging method with wettable flanks proposed by the present scheme; Figure 6 FIG. 6 is a groove width schematic diagram of the integrated circuit packaging method with wettable flanks proposed by the present scheme; Figure 7 The groove of the integrated circuit packaging method with wettable side wings proposed in this invention is shown in the technical schematic diagram. Figure 8 This is a schematic diagram of a tank for an integrated circuit packaging method with wettable side wings proposed in this invention.

[0016] Among them, 1. Pin; 2. Tank; 3. Side blow nozzle; 4. Plating; 5. Product; 6. Plastic seal; 7. Laser spot; 8. Pin thickness.

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0020] like Figures 1-8 As shown, this invention proposes an integrated circuit packaging method with wettable side wings, such as... Figure 1 As shown, the process includes step one: preparing the product 5 to be packaged. The product bar contains a pin 1 structure. The product bar is encapsulated as a whole through a plastic encapsulation process, forming a plastic encapsulation layer 6 on the product surface to complete the basic encapsulation and protection of the product, providing a stable structural base for subsequent laser processing and preventing the pin 1 from deforming during processing.

[0021] like Figure 2 As shown, step two: forming a corresponding groove 2 on the pin 1 of product 5 by laser drilling. The groove 2 is circular or elliptical in shape. Laser cold processing is performed using a picosecond / femtosecond high-frequency laser to form the preset groove 2 on the pin 1 of the product.

[0022] It should be noted that laser cold processing can directly sublimate materials from a solid to a gaseous state, with almost no excess heat residue. This avoids melting or high-temperature damage to the material surrounding pin 1, and the resulting groove 2 has a rounded side. Figure 7 As shown, compared to the traditional stepped side cut, such as Figure 8 As shown, the present invention forms a corresponding groove 2 on the pin 1 with a larger side area, which is more conducive to side soldering during subsequent soldering, thus improving soldering reliability. Compared with the half-cut solution used in mass production in the industry, it does not require complicated additional pre-plating etching and stripping processes.

[0023] like Figure 5 As shown, it should be noted that the laser processing angle in the Z-axis direction is configured as a vertical angle, or an offset angle within the range of 45° to 70° is selected for laser irradiation. This can adapt to the layout requirements of different pins 1, ensuring that the groove 2 can be accurately processed in the target area of ​​the pin 1. Inert gases such as argon and nitrogen are used to cover the laser focus area through the Z-axis or side-blowing nozzle 3 to physically isolate oxygen and prevent oxidation of the pin 1 surface. Finally, a clean surface with almost no oxidation can be obtained. Under effective gas protection, a clean surface with almost no oxidation can be obtained.

[0024] The laser focal area is the width of the groove 2, and the width of the groove 2 is the arc length between the two points where the pin 1 and the laser spot 7 intersect. This definition can accurately match the spot characteristics of laser processing and ensure the consistency of the width of the groove 2.

[0025] It should be noted that the groove 2 on pin 1 is circular or elliptical. Compared with the side of the step formed by traditional cutting, the groove 2 is arc-shaped, and the side area of ​​the groove 2 is larger than that of the step, which is beneficial for side soldering. The depth of the groove 2 ranges from 0 to 90% of the pin thickness 8, preferably 1 / 3 to 2 / 3 of the pin thickness 8, to ensure the wettable area of ​​the groove 2 without compromising the structural strength of the pin 1.

[0026] like Figure 6 As shown, it should be noted that the width of the groove 2 is slightly greater than or equal to the width of the adjacent pins 1, with a maximum difference of "πr-2r≈1.14r", where r is the radius of the laser spot 7. This setting can prevent the groove 2 from being too wide, which would cause short circuits in the adjacent areas of the pins 1, while ensuring the effective wettable width of the groove 2.

[0027] like Figure 3 As shown, step three: electroplating is performed on the surface of pin 1 after the tank body processing is completed, forming a protective plating layer 4 on the surface of pin 1 and tank body 2. The plating layer 4 can be a tin plating layer or other metal layers to achieve corrosion protection and optimize the welding performance of pin 1. At the same time, the arc side of tank body 2 is covered with plating layer 4 to further enhance solderability and ensure that the solder can be evenly spread on the arc side during subsequent welding.

[0028] like Figure 4 As shown, step four: using a single-chip cutting process, the strip product 5 that has completed plastic encapsulation, laser grooving, and electroplating is cut along a preset cutting path to obtain an independent single integrated circuit product, avoiding damage to the structure of pin 1 and groove 2, thus completing the entire packaging process.

[0029] This invention discloses an integrated circuit packaging structure with wettable side wings. The molding layer 6 covers the surface of the product 5, forming a physical protective barrier to protect the core circuit from external moisture, dust, and mechanical damage. The groove 2 on the pin 1 provides sufficient climbing space and contact interface for the solder. The plating layer 4 covers the surface of the groove, reducing the solder wetting angle, promoting uniform solder adhesion and climbing, ensuring the yield of the product 5, and meeting the application requirements of high-precision and high-reliability integrated circuits.

[0030] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0032] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method for packaging an integrated circuit with wettable side wings, characterized in that: The integrated circuit packaging method includes the following steps: Step 1: Prepare product (5) and perform plastic sealing operation on product (5); Step 2: A groove (2) is formed on the pin (1) of the product (5) by laser drilling. The laser drilling can be formed by laser cold processing with a high frequency laser. The side of the groove (2) is arc-shaped. Step 3: Electroplating is performed on the surface of the pin (1) to form a plating layer (4); Step 4: Cut the product (5) into individual pieces.

2. The integrated circuit packaging method with wettable side wings according to claim 1, characterized in that: The depth of the groove (2) ranges from 0 to 90% of the pin thickness (8).

3. The integrated circuit packaging method with wettable side wings according to claim 2, characterized in that: The depth of the groove (2) ranges from 1 / 3 to 2 / 3 of the pin thickness (8).

4. The integrated circuit packaging method with wettable side wings according to claim 1, characterized in that: The width of the groove (2) is greater than or equal to the width of the adjacent pins (1) on both sides, with a maximum difference of πr-2r≈1.14r, where r is the radius of the laser spot (7).

5. The integrated circuit packaging method with wettable side wings according to claim 4, characterized in that: The laser focal area on the groove (2) is the width of the groove (2), and the width of the groove (2) is the arc length between the two points where the pin (1) and the laser spot (7) intersect.

6. The integrated circuit packaging method with wettable side wings according to claim 1, characterized in that: The high-frequency laser emits laser light at a vertical angle or offset of 45°-70° along the Z-axis to form a laser spot (7).

7. The integrated circuit packaging method with wettable side wings according to claim 1, characterized in that: In step two, the tank (2) uses nozzles (3) to blow inert gas along the Z-axis or side to cover the laser focal area, which is used to physically isolate oxygen.

8. The integrated circuit packaging method with wettable side wings according to claim 1, characterized in that: The plating layer (4) is a tin plating layer or other metal layer.

9. The integrated circuit package structure with wettable side wings prepared by any one of the manufacturing methods of claims 1-8, characterized in that: The product (5) has a plastic sealing layer (6) on its surface. The product (5) includes a pin (1), a groove (2) on the pin (1), and a plating layer (4) on the groove (2).

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