Packaging jig for limiting CLIP

Abstract

The invention discloses a CLIP limiting packaging jig, and relates to the field of semiconductor power device packaging and manufacturing. The packaging structure comprises a limiting cover plate, a limiting base and a lead frame, the limiting base is installed below the limiting cover plate, the lead frame is installed in the limiting base in an embedded mode, a chip block is arranged above the lead frame, a solder paste assembly is arranged between the chip block and the lead frame, and the chip block and the lead frame are connected through the solder paste assembly. A CLIP is arranged above the solder paste assembly; a cover plate window is formed in the limiting cover plate, a U-shaped limiting column is fixedly connected to one side of the cover plate window, and four cover plate guide columns with the same diameter are fixedly connected to the top of the limiting cover plate. According to the invention, through the specific design of the lead frame structure and the CLIP frame structure, and the cooperation with the structure of the packaging tool, a fixed chip mounting position is maintained in the chip bonding reflow soldering process of the CLIP, and the corner and offset of the CLIP are avoided.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor power device packaging manufacturing, and particularly relates to a packaging fixture for a limiting CLIP. Background Art

[0002] With the continuous development of semiconductor power device packaging, higher requirements are put forward for the electrical performance and heat dissipation ability of products. In order to achieve better heat dissipation and smaller RDS(ON) simultaneously, a structural process of double-sided heat dissipation of the product + CLIP (copper sheet bonding) is usually adopted. The CLIP leaking to the top of the product can provide top heat dissipation, and cooperate with the bottom lead frame to achieve double-sided heat dissipation. At the same time, the CLIP as an internal electrical path can bring better product RDS(ON) and higher reliability. However, in actual production applications, when the CLIP is pasted above the chip and through the reflow soldering process, the die bonding material (solder paste) is in a molten state. At this time, the CLIP will generate rotation and offset due to the action of tension and center of gravity. If the rotation and offset of the CLIP are uncontrollable, it may lead to poor internal electrical performance of the product, poor package appearance, reduction of the top heat dissipation area, etc., resulting in a low package yield of the product.

[0003] The existing technical solutions limit the rotation and offset of the CLIP by designing an interlocking buckle structure between the CLIP and the lead frame. However, with the higher requirements for power density in power device packaging, the package volume of the product is continuously reduced, or the CLIP structure design is relatively complex. The smaller product volume results in no space for designing the buckle structure between the CLIP frame and the lead frame structure, and the more complex CLIP structure limits the CLIP from implementing the design of the buckle structure, making it impossible for smaller volume products to achieve the process ability of limiting the rotation angle of the CLIP.

[0004] Moreover, the technical solutions of the existing buckle structures make the CLIP structure and the lead frame structure relatively complex, resulting in larger sizes of the CLIP and the lead frame, lower material utilization rate, and higher precision requirements for the dimensional tolerances of multiple mating parts, bringing a significant increase in the production and manufacturing costs of the lead frame and CLIP materials. Summary of the Invention

[0005] The object of the present invention is to provide a packaging fixture for a limiting CLIP. During the reflow soldering process, the CLIP is limited by the packaging fixture, thereby realizing the limitation of the CLIP during the reflow soldering process and ensuring the packaging yield. A limiting notch is designed on the CLIP, and at the same time, a matching limiting post is designed on the packaging fixture. During the CLIP chip mounting process, the notch of the CLIP and the limiting post of the packaging fixture are matched. The CLIP takes the limiting post as an orbit and slides into the packaging fixture from top to bottom. After chip mounting, the lead frame, the CLIP copper sheet, and the packaging fixture are placed together in a vacuum reflow furnace for reflow soldering. During the reflow process, the packaging fixture limits the CLIP copper sheet, ensuring that the paste position of the CLIP copper sheet does not rotate or shift. After the reflow soldering is completed, the packaging fixture is removed to complete the CLIP die bonding.

[0006] To solve the above technical problems, the present invention is realized through the following technical solutions.

[0007] The present invention relates to a packaging fixture for a limiting CLIP, which includes a limiting cover plate, a limiting base, and a lead frame. The limiting base is installed below the limiting cover plate. The lead frame is embedded and installed inside the limiting base. A chip block is arranged above the lead frame. A solder paste assembly is arranged between the chip block and the lead frame. A CLIP is arranged above the solder paste assembly. A cover plate opening window is opened inside the limiting cover plate. A U-shaped limiting post is fixedly connected to one side of the cover plate opening window. Four cover plate guiding posts with the same diameter are fixedly connected to the top of the limiting cover plate. Four limiting seat guiding holes with the same diameter are opened at the inner top of the limiting base. An opening window is opened above the limiting base. A limiting seat bottom plate is fixedly connected inside the opening window. Two limiting seat guiding posts with the same diameter are fixedly connected to both sides of the top of the limiting seat bottom plate. A limiting seat rectangular groove is opened on the limiting seat bottom plate. Frame guiding holes are opened on both sides of the top of the lead frame. A frame carrier and frame pins are respectively fixedly installed on the top of the lead frame.

[0008] The present invention is further provided that the solder paste assembly includes carrier solder paste, chip solder paste, and frame solder paste. The chip block is pasted above the frame carrier through the carrier solder paste. The CLIP is pasted above the chip block through the chip solder paste. One side of the bottom of the CLIP is pasted above the frame pin through the frame solder paste.

[0009] The present invention is further provided that two guiding U-grooves are symmetrically opened on both sides of the CLIP. The guiding U-grooves are matched with the U-shaped limiting post, and the matching gap is designed to be 0.05 mm.

[0010] The present invention is further configured such that the cover guiding columns are designed at the center positions of the four side frames on the top of the limiting cover, and the cover window openings are designed to be arranged in a rectangular array, which can be multiple rows and multiple columns, and a single cover window opening corresponds to a single unit product of the lead frame.

[0011] The present invention is further configured such that the limiting base is a whole rectangular alloy plate, the depth of the window opening is designed to be greater than twice the thickness of the lead frame, and the size of the length multiplied by the width of the window opening is greater than the size of the length multiplied by the width of the lead frame, so that the lead frame can be completely placed into the window opening, and the guiding holes of the limiting seat cooperate with the cover guiding columns.

[0012] The present invention is further configured such that the number of rectangular grooves of the limiting seat is multiple, the size of the length multiplied by the width of the rectangular grooves of the limiting seat is designed to be the same as the size of the length multiplied by the width of the cover window openings, the positions of the rectangular grooves of the limiting seat are designed to be the same as those of the cover window openings, and the depth of the rectangular grooves of the limiting seat is designed to be 0.2 mm.

[0013] The present invention is further configured such that the frame carrier and the frame pin have the same material thickness and are designed on the same plane.

[0014] The beneficial effects of the present invention are as follows:

[0015] 1. Through the specific lead frame structure and CLIP frame structure design of the present invention, in cooperation with the structure of the encapsulation fixture, during the die bonding reflow soldering process of the CLIP, the fixed chip placement position is maintained, and no rotation or offset of the CLIP occurs.

[0016] 2. The present invention can solve the problems in the existing industry, such as the relatively high material cost brought by the anti-rotation and anti-offset structure design solutions where the lead frame and the CLIP frame are buckled with each other, the difficult material production and manufacturing due to the relatively complex material structure, and the large material waste, and greatly reduce the production cost.

[0017] 3. Through the specific encapsulation fixture structure of the present invention, only by designing a U-shaped or circular notch on the CLIP, the limiting of the CLIP can be achieved, solving the pain points in the existing industry for encapsulating products with extremely small sizes, where it is impossible to achieve limiting of the CLIP by designing a CLIP buckling structure due to the small size of the CLIP, or for relatively complex product structures where a CLIP buckling structure cannot be designed, enabling the limiting of the CLIP for any size and structure of the CLIP. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments will be briefly introduced below.

[0019] Figure 1 It is a three-dimensional view of the overall structure provided by the present invention;

[0020] Figure 2 Top view of the overall assembly structure provided by the present invention;

[0021] Figure 3 For the present invention Figure 2 Enlarged view of A in;

[0022] Figure 4 Schematic diagram of the limit base structure provided by the present invention;

[0023] Figure 5 For the present invention Figure 4 Enlarged view of B in;

[0024] Figure 6 Schematic diagram of the connection structure between the lead frame and the limit base provided by the present invention;

[0025] Figure 7 Schematic diagram of the lead frame structure provided by the present invention;

[0026] Figure 8 Schematic diagram of the solder paste component structure provided by the present invention;

[0027] Figure 9 Schematic diagram of the CLIP structure provided by the present invention;

[0028] Figure 10 Schematic diagram of the limit cover plate structure provided by the present invention.

[0029] Description of the drawings: 1. Limit cover plate; 11. Cover plate opening; 12. U-shaped limit post; 13. Cover plate guide post; 2. Limit base; 21. Limit base guide hole; 22. Limit base bottom plate; 23. Limit base guide post; 24. Limit base rectangular groove; 3. Lead frame; 31. Frame guide hole; 32. Frame carrier; 33. Frame pin; 4. Solder paste component; 41. Carrier solder paste; 42. Chip solder paste; 43. Frame solder paste; 5. Chip block; 6. CLIP; 61. Guide U groove. Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present invention will be described with reference to the accompanying drawings in the embodiments of the present invention. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0031] Embodiment 1

[0032] Please refer to Figures 1 - 10, the present invention is a packaging fixture for a limiting CLIP, comprising a limiting cover plate 1, a limiting base 2 and a lead frame 3. The limiting base 2 is installed below the limiting cover plate 1, and the lead frame 3 is embedded and installed inside the limiting base 2. A chip block 5 is arranged above the lead frame 3, a solder paste component 4 is arranged between the chip block 5 and the lead frame 3, and a CLIP 6 is arranged above the solder paste component 4; a cover plate opening 11 is formed inside the limiting cover plate 1, a U-shaped limiting post 12 is fixedly connected to one side of the cover plate opening 11, and four cover plate guiding posts 13 with the same diameter are fixedly connected to the top of the limiting cover plate 1; four limiting seat guiding holes 21 with the same diameter are formed in the inner top of the limiting base 2, an opening is formed above the limiting base 2, a limiting seat bottom plate 22 is fixedly connected inside the opening, two limiting seat guiding posts 23 with the same diameter are fixedly connected to both sides of the top of the limiting seat bottom plate 22, and a limiting seat rectangular groove 24 is formed in the limiting seat bottom plate 22; through the arrangement of the limiting seat rectangular groove 24, the frame carrier 32 and the frame pins 33 are prevented from being scratched or damaged. Frame guiding holes 31 are formed on both sides of the top of the lead frame 3, and a frame carrier 32 and frame pins 33 are respectively fixedly installed on the top of the lead frame 3.

[0033] As a preference of the above embodiment: the lead frame 3 is carried by the limiting base 2, the limiting guiding posts on the base are designed to cooperate with the guiding holes of the lead frame 3, the chip block 5 is pasted on the lead frame 3, the CLIP 6 is pasted on the surface of the chip block 5, the limiting cover plate 1 and the limiting seat guiding holes 21 cooperate with each other through the cover plate guiding posts 13, the limiting cover plate 1 and the CLIP 6 are designed with mutually cooperating U-grooves, and the limiting cover plate 1 limits the CLIP 6.

[0034] Embodiment 2

[0035] Please refer to Figures 1 - 10, on the basis of Embodiment 1, the solder paste assembly 4 includes a carrier solder paste 41, a chip solder paste 42, and a frame solder paste 43. The chip block 5 is pasted above the frame carrier 32 through the carrier solder paste 41, the CLIP 6 is pasted above the chip block 5 through the chip solder paste 42, and one side of the bottom of the CLIP 6 is pasted above the frame pin 33 through the frame solder paste 43. Two guiding U-grooves 61 are symmetrically opened on both sides of the CLIP 6, and the guiding U-grooves 61 cooperate with the U-shaped limiting posts 12, and the cooperation gap is designed to be 0.05 mm. The cover plate guiding posts 13 are designed at the center positions of the four side frames at the top of the limiting cover plate 1. The cover plate openings 11 are designed in a rectangular array arrangement, which can be multiple rows and multiple columns. A single cover plate opening 11 corresponds to a single unit product of the lead frame 3. The limiting base 2 is a whole rectangular alloy plate, and the opening depth is designed to be greater than twice the thickness of the lead frame 3. The size of the opening length multiplied by the width is greater than the length multiplied by the width of the lead frame 3, so that the lead frame 3 can be completely placed into the opening. The limiting seat guiding holes 21 cooperate with the cover plate guiding posts 13. The number of the rectangular grooves 24 on the limiting seat is multiple. The length multiplied by the width of the rectangular grooves 24 on the limiting seat is designed to be the same as the length multiplied by the width of the cover plate openings 11. The positions of the rectangular grooves 24 on the limiting seat are designed to be the same as those of the cover plate openings 11. The depth of the rectangular grooves 24 on the limiting seat is designed to be 0.2 mm. The frame carrier 32 and the frame pins 33 have the same material thickness and are designed on the same plane.

[0036] The working principle of the present invention includes the following steps:

[0037] The first step: The limiting base 2 is fixed on the tray through the equipment fixture. Multiple limiting bases 2 can be carried on one tray. The lead frame 3 is sucked and placed in the limiting base 2 through the suction nozzle of the mounter equipment. The limiting seat guiding posts 23 on the limiting base 2 cooperate with the lead frame guiding holes 31 on the lead frame 3, so that the lead frame 3 is fixed in the limiting base 2.

[0038] The second step: The mounter equipment smears the carrier solder paste 41 on the frame carrier 32; the mounter equipment picks up the chip block 5 and pastes it on the carrier solder paste 41.

[0039] The third step: The mounter equipment smears the chip solder paste 42 on the chip, and the mounter equipment smears the frame solder paste 43 on the frame pins 33.

[0040] The fourth step: The mounter equipment picks up the limiting cover plate 1, and through the cooperation of the cover plate guiding posts 13 and the limiting seat guiding holes 21, the limiting cover plate 1 is fixed on the limiting base 2.

[0041] The fifth step: The mounter picks up the CLIP 6 and pastes it on the chip solder paste 42 and the frame solder paste 43. The position of the CLIP 6 is fixed through the cooperation of the U-shaped limiting posts 12 and the CLIP guiding U-grooves 61, restricting the CLIP 6 from generating rotation angles and offsets.

[0042] Step 6: Place the entire tray into a vacuum reflow soldering furnace for solder paste reflow soldering. During the reflow soldering process, the position of the CLIP6 is fixed through the mutual cooperation of the U-shaped limit posts 12 and the guiding U-grooves 61, restricting the rotation angle and offset of the CLIP.

[0043] Step 7: After the reflow soldering is completed, the pick-and-place machine picks up the limit cover plate 1, removes the limit cover plate 1, the pick-and-place machine picks up the lead frame 3, and places the lead frame 3 with the chips and CLIPs attached into the cartridge, entering the next process.

[0044] Step 8: For the product after plastic encapsulation and molding, through grinding, the CLIP6 is exposed on the upper surface of the product.

[0045] Only some exemplary embodiments of the present invention have been described above by way of illustration. Without doubt, for those of ordinary skill in the art, the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An encapsulation fixture for a limiting CLIP, comprising a limiting cover plate (1), a limiting base (2) and a lead frame (3), characterized in that: The limiting base (2) is installed below the limiting cover plate (1). The lead frame (3) is embedded and installed inside the limiting base (2). Above the lead frame (3), there is a chip block (5). Between the chip block (5) and the lead frame (3), there is a solder paste assembly (4). Above the solder paste assembly (4), there is a CLIP (6). Inside the limiting cover plate (1), there is a cover plate opening window (11). On one side of the cover plate opening window (11), there is a U-shaped limiting post (12) fixedly connected. On the top of the limiting cover plate (1), there are four cover plate guiding posts (13) with the same diameter fixedly connected. On the inner top of the limiting base (2), there are four limiting base guiding holes (21) with the same diameter. Above the limiting base (2), there is an opening window. Inside the opening window, there is a limiting base bottom plate (22) fixedly connected. On both sides of the top of the limiting base bottom plate (22), there are limiting base guiding posts (23) with the same diameter fixedly connected. On the limiting base bottom plate (22), there is a limiting base rectangular groove (24). On both sides of the top of the lead frame (3), there are frame guiding holes (31) respectively. On the top of the lead frame (3), there are a frame carrier (32) and frame pins (33) fixedly installed respectively.

2. The encapsulation fixture for a limit CLIP according to claim 1, wherein: The solder paste assembly (4) includes carrier solder paste (41), chip solder paste (42), and frame solder paste (43). The chip block (5) is pasted above the frame carrier (32) through the carrier solder paste (41). The CLIP (6) is pasted above the chip block (5) through the chip solder paste (42). On one side of the bottom of the CLIP (6), it is pasted above the frame pins (33) through the frame solder paste (43).

3. The encapsulation fixture for a limiting CLIP according to claim 1, wherein: On both sides of the CLIP (6), there are two guiding U-grooves (61) symmetrically opened. The guiding U-grooves (61) cooperate with the U-shaped limiting post (12), and the clearance is designed to be 0.05 mm.

4. A packaging fixture for a limiting CLIP according to claim 1, characterized in that: The cover plate guiding posts (13) are designed at the center positions of the four side frames on the top of the limiting cover plate (1). The cover plate opening window (11) is designed in a rectangular array layout, which can be multiple rows and multiple columns. Each single cover plate opening window (11) corresponds to a single unit product of the lead frame (3).

5. The encapsulation fixture for a limiting CLIP according to claim 1, wherein: The limiting base (2) is a whole rectangular alloy plate. The depth of the opening window is designed to be greater than twice the thickness of the lead frame (3). The size of the length multiplied by the width of the opening window is greater than the size of the length multiplied by the width of the lead frame (3), so that the lead frame (3) can be completely placed into the opening window. The limiting base guiding holes (21) cooperate with the cover plate guiding posts (13).

6. The encapsulation fixture for a limiting CLIP according to claim 1, characterized in that: The number of the limiting base rectangular grooves (24) is multiple. The size of the length multiplied by the width of the limiting base rectangular grooves (24) is designed to be the same as that of the cover plate opening window (11). The positions of the limiting base rectangular grooves (24) are designed to be the same as those of the cover plate opening window (11). The depth of the limiting base rectangular grooves (24) is designed to be 0.2 mm.

7. A packaging fixture for a limiting CLIP according to claim 1, characterized in that: The frame carrier (32) and the frame pins (33) have the same material thickness and are designed on the same plane.

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