Large-current copper-plated bump structure

Abstract

The utility model relates to the field of high-current copper plating, in particular to a high-current copper plating bump structure, which can enhance the firmness of the bump structure and avoid the problem that a copper column is loosened and falls off. Comprising a chip at the bottom and an aluminum film layer on the upper side, a copper column is arranged on the upper side of the aluminum film layer, and an adhesion layer is arranged between the bottom surface of the copper column and the aluminum film layer; a circumferential annular groove is formed in the side surface of the bottom of the copper cylinder; the passivation layer around the copper cylinder extends into the annular groove to form a mutually matched embedding structure; the top surface of the copper column is provided with a nickel barrier layer, and the upper side of the nickel barrier layer is provided with a tin cap. The device is simple to operate, convenient to use and suitable for various circuit boards.

Description

Technical Field

[0001] This utility model relates to the field of high-current copper plating, specifically a high-current copper plating bump structure. Background Technology

[0002] In flip chip packaging technology, copper pillars are a key component. They replace the wire bonding process in traditional packaging, forming an electrical connection between the chip and the substrate and providing excellent heat dissipation. Made of copper, the copper pillars effectively transfer heat from the chip to the substrate or other components.

[0003] High-current copper bump plating refers to the process of plating copper using a high current, resulting in raised copper bumps on the substrate surface. These bumps are commonly found in copper interconnect processes, particularly in 3D packaging technology, where they are used to achieve 3D interconnect packaging of chips.

[0004] An existing copper-plated bump structure, such as Figure 1 As shown, the circuit includes a chip 1 at the bottom, an aluminum thin film layer 2 on the chip 1, a copper pillar 3 on the upper side of the aluminum thin film layer 2, a tin cap 5 on the top surface of the copper pillar 3, and a passivation layer 4 connected to the bottom of the copper pillar 3. This copper-plated bump structure can meet the requirements of the circuit board. However, during use, its defects were found: the bottom of the copper pillar is directly connected to the aluminum thin film layer, the connection is not firm, and the copper pillar is prone to loosening and falling off; the bottom of the copper pillar is a smooth structure without a reinforcing structure embedded in the passivation layer, which cannot limit the copper pillar from falling off. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-current copper-plated bump structure, which enhances the robustness of the bump structure and prevents the copper pillars from loosening and falling off.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a high-current copper-plated bump structure, comprising a chip at the bottom and an aluminum thin film layer on the upper side, with copper pillars provided on the upper side of the aluminum thin film layer, and an adhesive layer provided between the bottom surface of the copper pillars and the aluminum thin film layer;

[0007] The bottom side of the copper pillar is provided with a circumferential annular groove, and the passivation layer around the copper pillar extends into the annular groove to form a mutually cooperating interlocking structure.

[0008] The top surface of the copper pillar is provided with a nickel barrier layer, and a tin cap is provided on the upper side of the nickel barrier layer.

[0009] As a preferred technical solution, the adhesion layer is a titanium thin film layer.

[0010] As a preferred technical solution, the upper surface of the passivation layer is higher than the upper side surface of the annular groove.

[0011] As a preferred technical solution, the lateral depth of the annular groove is less than the radius of the copper pillar.

[0012] As a preferred technical solution, the vertical height of the annular groove is less than the height of the passivation layer.

[0013] As a preferred technical solution, an inverted T-shaped groove is embedded at the center of the top of the nickel barrier layer, and the bottom surface of the tin cap extends and is embedded in the inverted T-shaped groove.

[0014] As a preferred technical solution, the number of the inverted T-shaped grooves is at least one.

[0015] As a preferred technical solution, the height of the inverted T-shaped groove is half that of the nickel barrier layer.

[0016] Compared with the prior art, this utility model provides a high-current copper plating bump structure, which has the following beneficial effects:

[0017] 1. This utility model has an adhesive layer between the bottom surface of the copper column and the aluminum film layer. In use, the upper surface of the adhesive layer can be firmly connected to the column, and the bottom surface of the adhesive layer can be firmly connected to the upper surface of the aluminum film layer. The adhesive layer is a titanium film layer, which has high strength, good conductivity and corrosion resistance. It can be used as a transition material to effectively increase the firmness between the aluminum film layer and the copper column and reduce the problems caused by direct contact.

[0018] 2. This utility model features a circumferential annular groove on the bottom side of the copper column. The passivation layer around the copper column extends into the annular groove to form a mutually fitting interlocking structure. In use, the interlocking structure of the annular groove and the passivation layer restricts the copper column, effectively increasing its firmness and preventing it from loosening and falling off.

[0019] 3. This utility model has a nickel barrier layer on the top surface of the copper pillar, and a tin cap on the upper side of the nickel barrier layer. When in use, the nickel barrier layer can prevent the diffusion of copper and improve the solderability.

[0020] 4. This utility model features an inverted T-shaped groove embedded in the center of the top of the nickel barrier layer, with the bottom surface of the tin cap extending into the inverted T-shaped groove. In use, the inverted T-shaped groove structure increases the firmness between the tin cap and the nickel barrier layer, preventing the tin cap from falling off. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of the present invention, form part of this application:

[0022] Figure 1 This is a schematic diagram of an existing copper-plated bump structure;

[0023] Figure 2 This is a schematic diagram of the structure of the first embodiment of the present utility model;

[0024] Figure 3 This is a schematic diagram of the structure of the second embodiment of the present invention.

[0025] The diagram shows: 1. Chip; 2. Aluminum thin film layer; 3. Copper pillar; 31. Annular groove; 4. Passivation layer; 5. Tin cap; 6. Adhesion layer; 7. Nickel barrier layer; 71. Inverted T-shaped groove. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model. Example 1

[0027] like Figure 2 As shown, a high-current copper-plated bump structure includes a chip 1 at the bottom and an aluminum thin film layer 2 on the top. A copper pillar 3 is provided on the upper side of the aluminum thin film layer 2, and an adhesion layer 6 is provided between the bottom surface of the copper pillar 3 and the aluminum thin film layer 2. A circumferential annular groove 31 is provided on the bottom side of the copper pillar 3, and a passivation layer 4 around the copper pillar 3 extends into the annular groove 31 to form a mutually cooperating interlocking structure (which restricts the upward detachment of the copper pillar 3). A nickel barrier layer 7 is provided on the top surface of the copper pillar 3, and a tin cap 5 is provided on the upper side of the nickel barrier layer 7.

[0028] Adhesion layer 6 is a titanium thin film layer.

[0029] The height of the upper surface of the passivation layer 4 is higher than the height of the upper side surface of the annular groove 31.

[0030] The lateral depth of the annular groove 31 (on one side) is less than the radius of the copper pillar 3.

[0031] The vertical height of the annular groove 31 is less than the height of the passivation layer 4.

[0032] In use, the upper surface of the adhesive layer 6 can be firmly connected to the cylinder 3, and the bottom surface of the adhesive layer 6 can be firmly connected to the upper surface of the aluminum film layer 2. The adhesive layer 6 is a titanium film layer, which has high strength, good conductivity and corrosion resistance, and can be used as a transition material to effectively increase the firmness between the aluminum film layer 2 and the copper cylinder 3, reducing problems caused by direct contact. The interlocking structure of the annular groove 31 and the passivation layer 4 can effectively increase the firmness of the copper cylinder 3 and prevent loosening and falling off. The nickel barrier layer 7 can prevent copper diffusion and improve weldability. Example 2

[0033] like Figure 3 As shown, an inverted T-shaped groove 71 is embedded in the center of the top of the nickel barrier layer 7, and the bottom surface of the tin cap 5 extends and is embedded in the inverted T-shaped groove 7.

[0034] The number of inverted T-shaped grooves 71 is at least one.

[0035] The height of the inverted T-shaped groove 71 is half that of the nickel barrier layer 7.

[0036] In use, the inverted T-shaped groove 71 structure can increase the firmness of the tin cap 5 and the nickel barrier layer 7, preventing the tin cap 5 from falling off.

[0037] The components used in this utility model are all general standard parts or components known to those skilled in the art, and their structures and principles are well known to those skilled in the art.

[0038] It should be noted that, in this document, the terms "first," "second," "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are used only to distinguish one entity or operation from another entity or operation, without necessarily requiring or implying 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 a process, method, article, or apparatus.

[0039] The structures, proportions, sizes, etc. shown in the accompanying drawings of this specification are only used to complement the content disclosed in the specification, so that those skilled in the art can understand and read them, and are not intended to limit the conditions under which this utility model can be implemented. Any modification of the structure, change of the proportions, or adjustment of the size, without affecting the effects and purposes that this utility model can produce, should still fall within the scope of the technical content disclosed in this utility model.

[0040] Although embodiments of the present 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 present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-current copper-plated bump structure, comprising a bottom chip and an upper aluminum thin film layer, wherein copper pillars are provided on the upper side of the aluminum thin film layer, characterized in that: An adhesive layer is provided between the bottom surface of the copper pillar and the aluminum film layer; The bottom side of the copper pillar is provided with a circumferential annular groove, and the passivation layer around the copper pillar extends into the annular groove to form a mutually cooperating interlocking structure. The top surface of the copper pillar is provided with a nickel barrier layer, and a tin cap is provided on the upper side of the nickel barrier layer.

2. The high-current copper plating bump structure according to claim 1, characterized in that: The adhesion layer is a titanium thin film layer.

3. The high-current copper plating bump structure according to claim 1, characterized in that: The upper surface of the passivation layer is higher than the upper side of the annular groove.

4. The high-current copper plating bump structure according to claim 1, characterized in that: The lateral depth of the annular groove is less than the radius of the copper pillar.

5. The high-current copper plating bump structure according to claim 1, characterized in that: The vertical height of the annular groove is less than the height of the passivation layer.

6. The high-current copper plating bump structure according to claim 1, characterized in that: The nickel barrier layer has an inverted T-shaped groove at its top center, and the bottom surface of the tin cap extends into the inverted T-shaped groove.

7. The high-current copper plating bump structure according to claim 6, characterized in that: The number of the inverted T-shaped grooves is at least one.

8. The high-current copper plating bump structure according to claim 6, characterized in that: The height of the inverted T-shaped groove is half that of the nickel barrier layer.

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