Manufacturing method of preformed packaging lead frame

Abstract

The invention provides a manufacturing method of a preformed packaging lead frame. Forming a metal aluminum pattern layer on the temporary support plate; and executing a chemical replacement reaction procedure, so that at least one part of the metal aluminum pattern layer is replaced by metal copper, and the metal copper wire layer is obtained. A molding body is formed around the metal copper conductor layer. The temporary carrier is removed.

Description

Technical Field

[0001] The invention relates to a method for manufacturing a lead frame, in particular to a method for manufacturing a preformed package lead frame for semiconductor packaging. Background Art

[0002] Lead frames are one of the most important parts in semiconductor packaging structures as the electrical connection medium between the chip and the external circuit board. With the development of technology, preformed lead frames that can reduce the size of semiconductor packaging structures and reduce manufacturing costs have gradually become mainstream.

[0003] Generally speaking, the manufacturing of preformed lead frames is to bend or etch a metal sheet into a desired shape, and then coat the metal sheet with a preformed colloid. However, since the chips in various products have different electrical connection point distributions or the circuit boards have different solder point distributions, the industry needs to prepare multiple molds to manufacture preformed lead frames that meet product specifications, making it difficult to further reduce manufacturing costs. Summary of the invention

[0004] In view of the above problems, the present invention provides a method for manufacturing a preformed package lead frame, which helps to solve the problem that the existing method for manufacturing a preformed lead frame cannot further reduce the manufacturing cost.

[0005] The manufacturing method of the preformed package lead frame disclosed in the present invention includes the following steps: forming a first metal aluminum pattern layer on a temporary carrier; performing a chemical replacement reaction procedure to replace at least a portion of the first metal aluminum pattern layer with metal copper to obtain a first metal copper wire layer; forming a first mold body around the first metal copper wire layer; and removing the temporary carrier.

[0006] According to the manufacturing method of the preformed package lead frame disclosed in the present invention, at least a portion of the metal aluminum pattern layer is replaced with metal copper by a chemical replacement reaction to obtain a metal copper conductor layer. A metal copper conductor layer with a suitable pattern can be formed as a lead frame according to product specifications. Compared with the existing manufacturing method of using a mold to process a metal sheet, the method of forming a metal copper conductor layer by a chemical replacement reaction disclosed in the present invention has the advantage of lower manufacturing cost.

[0007] The above description of the content of the present invention and the following description of the implementation modes are used to demonstrate and explain the principles of the present invention and to provide further explanation for the protection scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figures 1 to 7 FIG. 1 is a schematic diagram of manufacturing a preformed package lead frame according to an embodiment of the present invention.

[0009] Figure 8FIG. 4 is a schematic diagram of a metal copper conductor layer according to another embodiment of the present invention.

[0010] Fig. 9 FIG. 4 is a schematic diagram of a semiconductor package structure including a preformed package lead frame according to an embodiment of the present invention.

[0011] Fig.10 FIG. 4 is a schematic diagram of a semiconductor package structure including a preformed package lead frame according to another embodiment of the present invention.

[0012] [Description of Reference Numerals]

[0013] 1: Preformed package lead frame

[0014] 2A, 2B: Semiconductor packaging structure

[0015] 10: Temporary board

[0016] 110: Bearing

[0017] 120: Outer frame

[0018] 21, 22: Metal aluminum pattern layer

[0019] 31, 32, 31”: Metal copper conductor layer

[0020] 310: Aluminum metal core

[0021] 320: Metallic copper film layer

[0022] 41, 42: Molded body

[0023] 50: Chip

[0024] 51: Metal lead

[0025] 60: Encapsulation layer

[0026] 70: Nickel immersion gold

[0027] L: Copper metal solution

[0028] UV: Ultraviolet light DETAILED DESCRIPTION

[0029] The detailed features and advantages of the present invention are described in detail in the following embodiments, and the contents are sufficient for ordinary technicians in the field to understand the technical content of the present invention and implement it accordingly. According to the contents, protection scope and drawings disclosed in this specification, ordinary technicians in the field can easily understand the present invention. The following examples further illustrate the viewpoints of the present invention in detail, but do not limit the scope of the present invention in any viewpoint.

[0030] Figures 1 to 7 FIG. 1 is a schematic diagram of manufacturing a preformed package lead frame according to an embodiment of the present invention. Figure 1 As shown, a temporary carrier 10 is provided. The temporary carrier 10 may include a carrier 110 and an outer frame 120 for fixing the carrier 110. The carrier 110 is, for example but not limited to, a heat released tape or an acid- and alkali-resistant film.

[0031] Next, a metal aluminum pattern layer 21 is formed on the temporary carrier 10. In this embodiment, the metal aluminum pattern layer 21 can be formed by screen printing. More specifically, the material of the metal aluminum pattern layer 21 can be an aluminum paste containing metal aluminum powder and a curable paste. The aluminum paste is printed on the temporary carrier 10 by screen printing in a pattern matching the distribution of chip electrical connection points or circuit board welding points, and then the curable paste is cured to form the metal aluminum pattern layer 21.

[0032] In this embodiment, the metal aluminum powder contained in the metal aluminum pattern layer 21 can be pure aluminum powder, aluminum alloy powder or copper-clad aluminum powder, wherein the proportion of aluminum element in the metal aluminum powder can be greater than or equal to 60%. The curable paste can contain a light-curing component or a heat-curing component, so the formation of the metal aluminum pattern layer 21 can be achieved by irradiation or heating. Figure 1 The exemplary diagram shows that the aluminum paste is photocured by irradiating ultraviolet light UV to form the metal aluminum pattern layer 21 .

[0033] like Figure 1 and Figure 2 As shown, a chemical replacement reaction process is performed to replace at least a portion of the metal aluminum pattern layer 21 with metal copper to obtain a metal copper conductor layer 31. In this embodiment, the chemical replacement reaction process is performed by treating the metal aluminum pattern layer 21 with a metal copper solution L. More specifically, the temporary carrier 10 and the metal aluminum pattern layer 21 can be immersed in the metal copper solution L, or the metal aluminum pattern layer 21 can be rinsed with the metal copper solution L.

[0034] In this embodiment, the metal copper solution L can be a copper sulfate solution. Copper sulfate and the metal aluminum pattern layer 21 undergo a chemical displacement reaction, so that the metal aluminum in the metal aluminum pattern layer 21 dissociates into the copper sulfate solution, and the copper ions of the copper sulfate precipitate and grow on the outer surface of the metal aluminum pattern layer 21. In this embodiment, the chemical displacement reaction process is performed at an appropriate reaction temperature and reaction time, so that the metal aluminum is replaced by the metal copper, thereby forming a metal copper wire layer 31 to replace Figure 1 The metal aluminum pattern layer 21 in the metal copper conductor layer 31 may be pure copper or copper-aluminum alloy, wherein the proportion of copper element in the metal copper conductor layer may be greater than or equal to 60%.

[0035] exist Figure 2In the embodiment, the metal aluminum pattern layer 21 is completely replaced by metal copper to obtain a metal copper conductor layer 31 that does not contain metal aluminum, but the present invention is not limited thereto. Figure 8 , is a schematic diagram of a metal copper conductor layer according to another embodiment of the present invention, wherein only a portion of the metal aluminum pattern layer close to the outer surface is replaced with metal copper, thereby obtaining a metal copper conductor layer 31" comprising a metal aluminum core 310 and a metal copper film layer 320 covering the metal aluminum core 310. Here, "excluding metal aluminum" means that the proportion of metal aluminum in the metal copper conductor layer may be less than or equal to 10%, preferably less than or equal to 1%.

[0036] like Figure 3 As shown, a molded body 41 is formed around the metal copper wire layer 31. In this embodiment, a molded body 41 is formed on the temporary carrier 10 to cover the side surface of the metal copper wire layer 31 and expose the upper surface of the metal copper wire layer 31. The material of the molded body 41 can be an organic composite material, a resin composite material, a high molecular composite material, a polymer composite material or other solid molded materials. For example, the molded body 41 can be epoxy resin.

[0037] like Figure 4 As shown, a metal aluminum pattern layer 22 is formed on the metal copper conductor layer 31. In this embodiment, the metal aluminum pattern layer 22 can be formed by screen printing. More specifically, aluminum paste can be printed on the metal copper conductor layer 31 and the mold package body 41 by screen printing, and then the aluminum paste is cured to form the metal aluminum pattern layer 22. The specific composition and properties of the aluminum paste and the metal aluminum pattern layer 22 can be referred to the above description, and will not be repeated here.

[0038] like Figure 4 and Figure 5 As shown, another chemical replacement reaction process is performed to replace at least a portion of the metal aluminum pattern layer 22 with metal copper, thereby obtaining a metal copper conductor layer 32. In this embodiment, the chemical replacement reaction process is performed by treating the metal aluminum pattern layer 22 with a metal copper solution L. In this embodiment, the chemical replacement reaction process is performed at an appropriate reaction temperature and reaction time, so that the metal aluminum is replaced by the metal copper, thereby forming a metal copper conductor layer 32 to replace Figure 4 The metal aluminum pattern layer 22 in the embodiment of the present invention. The specific composition and properties of the metal copper wire layer 32 can be referred to the above description, which will not be repeated here.

[0039] like Figure 6 As shown, a molded body 42 is formed around the metal copper wire layer 32. In this embodiment, a molded body 42 is formed on the molded body 41 to cover the side surface of the metal copper wire layer 32 and expose the upper surface of the metal copper wire layer 32. The molded body 42 can be epoxy resin.

[0040] like Figure 7 As shown, the temporary carrier 10 is removed to obtain a preformed package lead frame 1 including metal copper wire layers 31, 32 and molded bodies 41, 42. The preformed package lead frame 1 may have a Quad Flat NoLead (QFN) package structure, but the present invention is not limited thereto.

[0041] This embodiment manufactures a preformed package lead frame 1 including a double-layer lead structure (metal copper lead layers 31 and 32), but the present invention is not limited thereto. In other embodiments, Figures 4 to 6 The step of step 30 can be omitted, thereby manufacturing a preformed package lead frame with a single-layer wire structure (eg, only a metal copper wire layer 31).

[0042] According to the method for manufacturing a preformed package lead frame disclosed in the present invention, the chemical displacement reaction may be a redox reaction. The chemical displacement reaction may be a Galvanic displacement reaction.

[0043] The preformed packaging lead frame disclosed in the present invention can be applied to semiconductor packaging. Fig. 9 FIG. 2 is a schematic diagram of a semiconductor package structure including a preformed package lead frame according to an embodiment of the present invention. The semiconductor package structure 2A in this embodiment includes a chip 50, a packaging layer 60, and a semiconductor package structure including ... Figure 7 The preformed package lead frame 1 is shown. A chip 50 and metal leads 51 are disposed on one side of the preformed package lead frame 1, and this side of the preformed package lead frame 1 is covered by a packaging layer 60. The other side of the preformed package lead frame 1 can be processed to form electroless nickel immersion gold (ENIG) 70 on the lower surface of the metal copper wire layer 31.

[0044] Fig.10 FIG. 2 is a schematic diagram of a semiconductor package structure including a preformed package lead frame according to another embodiment of the present invention. The semiconductor package structure 2B in this embodiment includes a chip 50, a packaging layer 60, and a semiconductor package structure including a preformed package lead frame. Figure 7 The preformed package lead frame 1 is shown. The molding bodies 41 and 42 of the preformed package lead frame 1 are partially removed to expose the side surface of the metal copper wire layer 31 . The preformed package lead frame 1 can be processed to form electroless nickel immersion gold (ENIG) 70 on the side surface of the metal copper wire layer 31 .

[0045] In summary, according to the manufacturing method of the preformed package lead frame disclosed in the present invention, at least a portion of the metal aluminum pattern layer is replaced with metal copper by a chemical replacement reaction to obtain a metal copper conductor layer. A metal copper conductor layer with a suitable pattern can be formed as a lead frame according to product specifications. Compared with the existing manufacturing method of using a mold to process a metal sheet, the method of forming a metal copper conductor layer by a chemical replacement reaction disclosed in the present invention has the advantage of lower manufacturing cost.

Claims

1. A method for manufacturing a preformed package lead frame, characterized in that: Include: Forming a first metal aluminum pattern layer on a temporary carrier; Performing a chemical replacement reaction process to replace at least a portion of the first metal aluminum pattern layer with metal copper to obtain a first metal copper conductor layer; forming a first mold package around the first metal copper wire layer; and Remove the temporary carrier board.

2. The method for manufacturing a preformed package lead frame according to claim 1, wherein: The metal aluminum pattern layer is formed on the temporary carrier by screen printing and light curing or heat curing.

3. The method for manufacturing a preformed package lead frame according to claim 2, wherein: The metal aluminum pattern layer includes metal aluminum powder and a curable paste.

4. The method for manufacturing a preformed package lead frame according to claim 1, wherein: The chemical replacement reaction process is performed by treating the first metal aluminum pattern layer with a metal copper solution.

5. The method for manufacturing a preformed package lead frame according to claim 1, wherein: An outer surface of the first metal aluminum pattern layer is replaced with metal copper to obtain the first metal copper conductor layer including a metal aluminum core and a metal copper film layer covering the metal aluminum core.

6. The method for manufacturing a preformed package lead frame according to claim 1, wherein: The first metal aluminum pattern layer is completely replaced by metal copper to obtain the first metal copper wire layer that does not contain metal aluminum.

7. The method for manufacturing a preformed package lead frame according to claim 1, wherein: Also includes: forming a second metal aluminum pattern layer on the first metal copper conductor layer; Performing another chemical replacement reaction process to replace at least a portion of the second metal aluminum pattern layer with metal copper to obtain a second metal copper conductor layer; and A second mold package is formed around the second metal copper wire layer.

8. The method for manufacturing a preformed package lead frame according to claim 7, wherein: The other chemical replacement reaction process is performed by treating the second metal aluminum pattern layer with a metal copper solution.

9. The method for manufacturing a preformed package lead frame according to claim 7, wherein: An outer surface of the second metal aluminum pattern layer is replaced with metal copper to obtain the second metal copper conductor layer including a metal aluminum core and a metal copper film layer covering the metal aluminum core.

10. The method for manufacturing a preformed package lead frame according to claim 7, wherein: The second metal aluminum pattern layer is completely replaced by metal copper to obtain the second metal copper wire layer that does not contain metal aluminum.

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