High-heat-dissipation LQFP packaging structure and packaging method
By introducing silver glue and high-thermal DAF film layers into the LQFP packaging structure, combined with the exposed design of copper blocks and wire frame bases, the problem of insufficient heat dissipation performance of high-power devices in the prior art is solved, and more efficient heat dissipation effect and structure are achieved stability.
Patent Information
- Application Number
- CN202411347881.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-26
- Publication Date
- 2025-01-03
AI Technical Summary
The existing LQFP packaging structures lack the heat dissipation performance in high-power devices, and the thermal conductivity of the plastic-sealed colloid cannot meet the high heat dissipation needs.
Design a high heat dissipation LQFP packaging structure, ensuring copper by adding silver glue or high thermal conductivity DAF film between the base of the wire frame and the chip, and using a high thermal conductivity DAF film between the copper blocks, combined with the die-locking groove structure. The base of the block and wire frame is exposed to enhance the heat dissipation area and uses the elasticity of the high-thermal conductivity DAF film to maintain the structural stability during the injection molding process.
Without changing the overall package structure size, the heat dissipation performance is significantly improved. The exposed design of the copper block and wire frame base improves the heat dissipation effect, and the packaging stability is enhanced by curing the high-thermal DAF film.
Smart Images
Figure CN119252803A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of semiconductor packaging, in particular to a high heat dissipation LQFP packaging structure and a packaging method. Background Art
[0002] Semiconductor packaging uses plastic encapsulation to wrap chip ICs to protect the chip and internal circuits from damage and to dissipate heat. At present, the thermal conductivity of plastic encapsulation is 0.9W / (m·K). With the development of semiconductors, more and more high-power devices have emerged, and the requirements for heat dissipation are getting higher and higher. The packaging form with plastic encapsulation as the main heat dissipation medium can no longer meet the high heat dissipation requirements.
[0003] LQFP Low-profile Quad Flat Package is a package specification with a plastic package thickness of 1.4mm. The existing LQFP package structure is as follows Figure 1 As shown, the chip and the lead frame base are wrapped in a plastic encapsulation colloid as a whole, and the thickness of the colloid above and below the chip and the lead frame base is about 600 μm, which has poor heat dissipation performance for high-power products. Summary of the invention
[0004] The present invention provides a high heat dissipation LQFP packaging structure and a packaging method to overcome the deficiencies of the prior art.
[0005] To achieve the above purpose, a high heat dissipation LQFP packaging structure is designed, including a lead frame base, a chip is arranged above the lead frame base, the outer side above the chip is connected to one end of a lead pin through a lead wire, a copper block 1 is arranged above the middle of the chip, a copper block 2 is arranged above the copper block 1, the lead frame base, the chip, the copper block 1 and the copper block 2 are wrapped with a plastic sealing colloid, the bottom of the plastic sealing colloid is exposed from the lead frame base, the copper block 2 is exposed from the top of the plastic sealing colloid, one end of the lead pin connected to the lead wire is wrapped on the inner side of the plastic sealing colloid, and the other end of the lead pin extends out of the plastic sealing colloid.
[0006] A first adhesive film layer is arranged between the chip and the lead frame base, a second adhesive film layer is arranged between the first copper block and the chip, and a third adhesive film layer is arranged between the second copper block and the first copper block.
[0007] The first adhesive film layer is silver adhesive or a high thermal conductivity DAF film, and the second adhesive film layer and the third adhesive film layer are high thermal conductivity DAF films.
[0008] The outer side of the bottom of the lead frame base and the outer side of the top of the second copper block are provided with a film locking groove.
[0009] The present invention also provides a packaging method for the above-mentioned high heat dissipation LQFP packaging structure, comprising: S1: Use silver glue or high thermal conductivity DAF glue film to attach the chip to the lead frame base, and form the first glue film layer between the chip and the lead frame base; S2: First baking to solidify the first adhesive film layer; S3: Bond the chip to the lead pins with wires; S4: A copper block 1 is mounted on the chip using a high thermal conductivity DAF adhesive film, and a second adhesive film layer is formed between the chip and the copper block 1; S5: mounting copper block 2 on copper block 1 using a high thermal conductivity DAF adhesive film, and forming a third adhesive film layer between copper block 2 and copper block 1; S6: baking for the second time to bond the upper and lower sides of the second adhesive film layer to the third adhesive film layer; S7: placing the lead frame base into a plastic encapsulation mold cavity for plastic encapsulation, wherein the height of the plastic encapsulation mold cavity is less than the thickness of the overall stacked structure; S8: The third baking makes the plastic encapsulation colloid and the high thermal conductivity DAF film completely solidified; S9: After segmentation, the guide pins are bent and formed.
[0010] The thickness of the lead frame base is 127um, the thickness of the first film layer is 23um, the thickness of the chip is 350um, the thickness of copper block one is 400um, the thickness of copper block two is 400um, the thickness of the second film layer before plastic packaging is 70~80um, and the thickness of the third film layer is 70~80um.
[0011] The chip preparation method in step S1 includes: S1.1: Thinning the wafer; S1.2: attaching the wafer to the support film; S1.3: Divide the wafer into individual chips.
[0012] The method for preparing the copper sheet 1 in step S4 comprises: S4.1: Bond one side of the copper sheet to the high thermal conductivity DAF film; S4.2: Split the copper sheet into a copper block.
[0013] The preparation method of the copper sheet 2 in step S5 comprises: S5.1: Etching a groove on one side of the copper sheet; S5.2: Bond the other side of the copper sheet with the high thermal conductivity DAF film; S5.3: Split the copper sheet along the center line of the groove to form copper block 2.
[0014] Compared with the prior art, the present invention performs internal stacking without changing the size of the overall LQFP packaging structure, exposes the lead frame base and the heat dissipation copper sheet, and improves the heat dissipation performance; and utilizes the elasticity of the high thermal conductivity DAF film to make the copper block 2 and the lead frame base fit on the mold surface during packaging, and after injection molding, the copper block 2 and the lead frame base are directly exposed to the outside without the need for polishing. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 A schematic diagram of an existing packaging structure.
[0016] Figure 2 It is a schematic diagram of the packaging structure of the present invention.
[0017] Figure 3 is a schematic diagram of step S1.
[0018] Figure 4 is a schematic diagram of step S3.
[0019] Figure 5 is a schematic diagram of step S4.
[0020] Figure 6 is a schematic diagram of step S5.
[0021] Figure 7 is a schematic diagram of step S7.
[0022] Figure 8 is a schematic diagram of step S9.
[0023] See also Figure 1-Figure 8 , where 1 is the lead frame base, 2 is the first film layer, 3 is the chip, 4 is the lead, 5 is the lead pin, 6 is the second film layer, 7 is the copper block one, 8 is the third film layer, 9 is the copper block two, 10 is the plastic encapsulation colloid, and 11 is the locking groove. DETAILED DESCRIPTION
[0024] The present invention will be further described below with reference to the accompanying drawings.
[0025] like Figure 2 As shown, the present invention provides a high heat dissipation LQFP packaging structure, including a lead frame base 1, a chip 3 is arranged above the lead frame base 1, the outer side above the chip 3 is connected to one end of a lead pin 5 through a lead wire 4, a copper block 1 7 is arranged above the middle of the chip 3, a copper block 2 9 is arranged above the copper block 1 7, the lead frame base 1, the chip 3, the copper block 1 7, and the copper block 2 9 are wrapped with a plastic encapsulation colloid 10, the lead frame base 1 exposes the bottom of the plastic encapsulation colloid 10, the copper block 2 9 exposes the top of the plastic encapsulation colloid 10, one end of the lead pin 5 connected to the lead wire 4 is wrapped around the inner side of the plastic encapsulation colloid 10, and the other end of the lead pin 5 extends out of the plastic encapsulation colloid 10.
[0026] A first adhesive film layer 2 is provided between the chip 3 and the lead frame base 1 , a second adhesive film layer 6 is provided between the copper block 1 7 and the chip 3 , and a third adhesive film layer 8 is provided between the copper block 2 7 and the copper block 1 7 .
[0027] The first adhesive film layer 2 is silver adhesive or a high thermal conductivity DAF film, and the second adhesive film layer 6 and the third adhesive film layer 8 are high thermal conductivity DAF films.
[0028] The outer bottom surface of the lead frame base 1 and the outer top surface of the copper block 2 9 are provided with a film locking groove 11 .
[0029] The copper block 1 7 and copper block 2 9 of the packaging structure are exposed to the plastic encapsulation colloid 10 to improve the heat dissipation effect. The lead frame base 1 is bonded to the chip 3 through silver glue, and the silver glue contains silver powder, which has a good thermal conductivity. The upper outer side of the chip 3 is connected to the lead pin 7 through the lead 4, and the lead pin 7 is connected to the external point. The copper block 1 7 is mounted on the middle of the upper part of the chip 3 through the second adhesive film layer 6, avoiding the pad connected to the lead 4 above the chip 3. The copper block 2 9 is mounted on the upper part of the copper block 1 7 through the third adhesive film layer 6. The area of the copper block 2 9 is larger than the area of the copper block 1 7, and can cover the upper part of the lead 4, which can expand the heat dissipation area and improve the heat dissipation effect. The locking groove 11 can use the plastic encapsulation colloid 10 to lock the laminated structure in the packaging structure to prevent the copper block 2 9 and the lead frame base 1 from being delaminated with the plastic encapsulation colloid 10.
[0030] like Figure 3-Figure 8 As shown, the present invention provides a packaging method of a high heat dissipation LQFP packaging structure, comprising: S1: Using silver glue or high thermal conductivity DAF glue film to attach the chip 3 to the lead frame base 1, and forming a first glue film layer 2 between the chip 3 and the lead frame base 1; S2: first baking to solidify the first adhesive film layer 2; S3: Bonding the chip 3 to the lead pin 5 with the lead wire 4; S4: mounting a copper block 7 on the chip 3 using a high thermal conductivity DAF adhesive film, and forming a second adhesive film layer 6 between the chip 3 and the copper block 7; S5: mounting copper block 2 9 on copper block 1 7 using a high thermal conductivity DAF adhesive film, and forming a third adhesive film layer 8 between copper block 2 9 and copper block 1 7; S6: baking for the second time to make the upper and lower sides of the second adhesive film layer 6 and the third adhesive film layer 8 adhere to each other; S7: placing the lead frame base 1 into a plastic encapsulation mold cavity for plastic encapsulation, wherein the height of the plastic encapsulation mold cavity is less than the thickness of the overall stacked structure; S8: The third baking allows the plastic encapsulation 10 and the high thermal conductivity DAF film to be completely cured; S9: After segmentation, the guide pin 5 is bent and formed.
[0031] The thickness of the lead frame base 1 is 127um, the thickness of the first adhesive film layer 2 is 23um, the thickness of the chip 3 is 350um, the thickness of the copper block 1 7 is 400um, the thickness of the copper block 2 9 is 400um, the thickness of the second adhesive film layer 6 before plastic encapsulation is 70-80um, and the thickness of the third adhesive film layer 8 is 70-80um. In this embodiment, the thickness of the second adhesive film layer 6 before plastic encapsulation is 80um, and the thickness of the third adhesive film layer 8 is 80um.
[0032] The chip preparation method in step S1 includes: S1.1: Thinning the wafer; S1.2: attach the wafer to the support film, and the support film is ordinary blue film; S1.3: Divide the wafer into individual chips 3.
[0033] The method for preparing the copper sheet 1 in step S4 includes: S4.1: Bond one side of the copper sheet to the high thermal conductivity DAF film; S4.2: Divide the copper sheet into copper blocks 7.
[0034] The preparation method of the copper sheet 2 in step S5 includes: S5.1: Etching a groove on one side of the copper sheet; S5.2: Bond the other side of the copper sheet with the high thermal conductivity DAF film; S5.3: Divide the copper sheet along the center line of the groove to form a copper block 9.
[0035] Specifically, if silver glue is used in step S1, the first baking can completely solidify the silver glue, and then copper block 1 7 and copper block 2 9 are mounted. When preparing copper block 1 7 and copper block 2 9, the bonding temperature of the copper sheet and the high thermal conductivity DAF is 65°. The second baking makes the second adhesive film layer 6 stick to the chip and the third adhesive film layer 8 stick to the copper block 2 9. The temperature of the plastic sealing colloid during plastic sealing is 175°. The high thermal conductivity DAF film will become soft and elastic after being heated. When the mold cavity is closed, the second adhesive film layer 6 and the third adhesive film layer 8 will be compressed and thinned, providing a buffer for the entire structure to prevent the chip from being crushed, and at the same time making the copper block 2 9 and the lead frame base 1 fit on the mold surface. The third baking is maintained at 175° for four hours to completely solidify the plastic sealing colloid 10. The high thermal conductivity DAF film loses its thermoplastic properties and will be completely solidified, further improving the stability of the entire package.
Claims
1. A high heat dissipation LQFP packaging structure, characterized in that: The invention comprises a lead frame base (1), a chip (3) is arranged above the lead frame base (1), the outer side of the chip (3) is connected to one end of a lead pin (5) through a lead wire (4), a copper block (7) is arranged above the middle of the chip (3), a copper block (9) is arranged above the copper block (7), the lead frame base (1), the chip (3), the copper block (7) and the copper block (9) are wrapped with a plastic seal (10), the lead frame base (1) exposes the bottom of the plastic seal (10), the copper block (9) exposes the top of the plastic seal (10), one end of the lead pin (5) connected to the lead wire (4) is wrapped around the inner side of the plastic seal (10), and the other end of the lead pin (5) protrudes out of the plastic seal (10).
2. The high heat dissipation LQFP packaging structure according to claim 1, characterized in that: A first adhesive film layer (2) is provided between the chip (3) and the lead frame base (1), a second adhesive film layer (6) is provided between the copper block 1 (7) and the chip (3), and a third adhesive film layer (8) is provided between the copper block 2 (7) and the copper block 1 (7).
3. The high heat dissipation LQFP packaging structure according to claim 2, characterized in that: The first adhesive film layer (2) is silver adhesive or a high thermal conductivity DAF film, and the second adhesive film layer (6) and the third adhesive film layer (8) are high thermal conductivity DAF films.
4. The high heat dissipation LQFP packaging structure according to claim 1, characterized in that: The outer bottom surface of the lead frame base (1) and the outer top surface of the second copper block (9) are provided with a film locking groove (11).
5. A packaging method for the high heat dissipation LQFP packaging structure according to any one of claims 1 to 4, characterized in that: include: S1: using silver glue or high thermal conductivity DAF glue film to stick the chip (3) onto the lead frame base (1), so that a first glue film layer (2) is formed between the chip (3) and the lead frame base (1); S2: first baking to solidify the first adhesive film layer (2); S3: bonding the chip (3) to the lead pin (5) using a wire (4); S4: mounting a copper block 1 (7) on the chip (3) using a high thermal conductivity DAF adhesive film, and forming a second adhesive film layer (6) between the chip (3) and the copper block 1 (7); S5: Mounting copper block 2 (9) on copper block 1 (7) using a high thermal conductivity DAF adhesive film, and forming a third adhesive film layer (8) between copper block 2 (9) and copper block 1 (7); S6: baking for the second time to bond the upper and lower sides of the second adhesive film layer (6) and the third adhesive film layer (8); S7: placing the lead frame base (1) into a plastic encapsulation mold cavity for plastic encapsulation, wherein the height of the plastic encapsulation mold cavity is less than the thickness of the overall stacked structure; S8: The third baking is performed to completely solidify the plastic encapsulation colloid (10) and the high thermal conductivity DAF film; S9: After segmentation, the guide pin (5) is bent to form.
6. The packaging method of the high heat dissipation LQFP packaging structure according to claim 5, characterized in that: The thickness of the lead frame base (1) is 127um, the thickness of the first adhesive film layer (2) is 23um, the thickness of the chip (3) is 350um, the thickness of the first copper block (7) is 400um, the thickness of the second copper block (9) is 400um, the thickness of the second adhesive film layer (6) before plastic sealing is 70-80um, and the thickness of the third adhesive film layer (8) is 70-80um.
7. The packaging method of the high heat dissipation LQFP packaging structure according to claim 5, characterized in that: The chip preparation method in step S1 includes: S1.1: Thinning the wafer; S1.2: attaching the wafer to the support film; S1.3: Divide the wafer into individual chips (3).
8. The packaging method of the high heat dissipation LQFP packaging structure according to claim 5, characterized in that: The method for preparing the copper sheet 1 in step S4 comprises: S4.1: Bond one side of the copper sheet to the high thermal conductivity DAF film; S4.2: Divide the copper sheet into a copper block (7).
9. The packaging method of the high heat dissipation LQFP packaging structure according to claim 5, characterized in that: The preparation method of the copper sheet 2 in step S5 comprises: S5.1: Etching a groove on one side of the copper sheet; S5.2: Bond the other side of the copper sheet with the high thermal conductivity DAF film; S5.3: Split the copper sheet along the center line of the groove to form copper block 2 (9).