Rfid chip bump structure, rfid chip and rfid tag

Abstract

The utility model provides a kind of RFID chip bump structure, RFID chip and RFID label, comprising: first metal layer, second metal layer and third metal layer;The lower surface of third metal layer is electrically connected with the surface of RFID chip, second metal layer is connected in the upper surface of third metal layer, and first metal layer is connected in the upper surface of second metal layer;Second metal layer is partially / entirely exposed after first metal layer is destroyed, to reduce electrical performance;Or, third metal layer is partially / entirely exposed after first metal layer, second metal layer is destroyed, to reduce electrical performance.The utility model can be transferred when chip, first metal layer is corroded and causes middle layer partially / entirely exposed outside, make the electrical performance of re-bound chip greatly attenuate, even lead to RFID label cannot be read, to improve the difficulty of RFID chip transfer reuse.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor process technology, specifically to an RFID chip bump structure, an RFID chip, and an RFID tag. Background Technology

[0002] Bumping technology involves creating bumps on a chip. These metal bumps provide "point" interfaces for electrical interconnection between the chip and the substrate, and are widely used in advanced packaging such as FC, WLPCSP, and 3D. Bumps are conductive protrusions that grow directionally on the chip surface and are directly or indirectly connected to chip pads. The bumping process lies between front-end integrated circuit manufacturing and back-end packaging and testing in the industry chain, and is one of the core technologies of advanced packaging.

[0003] In the field of RFID anti-counterfeiting and traceability, confirming the uniqueness of the target item is crucial. To achieve this, existing technologies have added various security functions to traditional RFID chips to ensure item uniqueness. For example, patent document CN206961164U discloses an intelligent logistics anti-counterfeiting and traceability electronic tag based on RFID technology, which achieves anti-counterfeiting of the target item through logistics traceability. However, this technology still cannot prevent counterfeiters from recycling legitimate packaging materials to make counterfeit goods. This is because the RFID chip can be separated from the antenna using an acidic solution, allowing the complete chip to be removed and re-bound into a tag. In this case, RFID identification of these remade tags will retrieve authentic information, thus allowing counterfeit goods to be "packaged" as genuine products. Utility Model Content

[0004] In view of the deficiencies in the prior art, the purpose of this utility model is to provide an RFID chip bump structure, an RFID chip, and an RFID tag.

[0005] According to the present invention, an RFID chip bump structure includes multiple layers of metal layers that are stacked and electrically connected in sequence. The electrical properties of the multiple metal layers are different; After at least one of the multi-layer metal layers is damaged in the direction from farthest to near the RFID chip, the internal metal layers are partially or completely exposed, thereby changing the overall electrical performance of the RFID chip bump structure.

[0006] Furthermore, among the multi-layered metal layers, the metal layer furthest from the RFID chip is the gold layer.

[0007] Furthermore, the multilayer metal layer has a three-layer structure, including: a first metal layer, a second metal layer, and a third metal layer; The lower surface of the third metal layer is used for surface electrical connection with the RFID chip, the second metal layer is connected to the upper surface of the third metal layer, and the first metal layer is connected to the upper surface of the second metal layer; The second metal layer is partially or completely exposed after the first metal layer is damaged; or, the third metal layer is partially or completely exposed after the first metal layer and the second metal layer are damaged.

[0008] Furthermore, when the second metal layer is partially or completely exposed after the first metal layer is damaged, the second metal layer is a copper layer and the third metal layer is a nickel layer.

[0009] Furthermore, when the third metal layer is partially or completely exposed after the first metal layer and the second metal layer are damaged, the third metal layer is a copper layer.

[0010] Furthermore, the chip bump structure has a multi-layer planar structure.

[0011] Furthermore, the chip bump structure is a multi-layered arc-shaped bump structure.

[0012] Furthermore, the reduction in electrical performance includes: oxidation of the exposed metal layer leading to a decrease in conductivity or a decrease in high-frequency performance.

[0013] An RFID chip according to the present invention includes the aforementioned RFID chip bump structure, wherein the metal layer closest to the RFID chip in the multilayer metal layers of the RFID chip bump structure is electrically connected to the surface of the RFID chip.

[0014] An RFID tag according to the present invention includes an RFID chip and an antenna, wherein the antenna is electrically connected to the metal layer farthest from the RFID chip in the multilayer metal layer of the RFID chip bump structure.

[0015] Compared with the prior art, the present invention has the following beneficial effects: Through the structural design of this utility model, when the chip is transferred, the first metal layer is corroded, causing the middle layer to be partially or completely exposed. This significantly degrades the electrical performance of the re-bonded chip, and may even cause the RFID tag to become unreadable, thereby increasing the difficulty of transferring and reusing the RFID chip. Attached Figure Description

[0016] Other features, objects, and advantages of this invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of an RFID chip bump structure according to the present invention; Figure 2 This is a schematic diagram of another RFID chip bump structure according to the present invention. Detailed Implementation

[0017] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0018] Example 1 like Figure 1 As shown, this embodiment provides an RFID chip bump structure with a three-layer planar structure, including: a first metal layer 1, a second metal layer 2, and a third metal layer 3. This embodiment uses multiple metal bumpings without increasing the volume compared to traditional bump structures, and the electrical properties of each metal differ. The lower surface of the third metal layer 3 is electrically connected to the surface of the RFID chip, the second metal layer 2 is connected to the upper surface of the third metal layer 3, and the first metal layer 1 is connected to the upper surface of the second metal layer 2. When the first metal layer 1 is cleaned with an acidic solution, it can be corroded, thereby exposing the second metal layer 2; or, the first metal layer 1 and the second metal layer 2 can be corroded when cleaned with an acidic solution, thereby exposing the third metal layer 3. Therefore, changes to the bump structure lead to changes in the electrical properties of the bump structure, including: reduced conductivity or reduced high-frequency performance.

[0019] When the outermost first metal layer 1 of the bump structure is partially or completely corroded, the second metal layer 2 covered by it is partially or completely exposed. This alters the electrical properties of the chip bump and also changes its size. The change in electrical properties significantly affects the chip's frequency and read / write distance, while the change in bump size drastically reduces the yield of secondary bonding. In other embodiments, the corrosion of the first and second metal layers 1 can also lead to the partial or complete exposure of the third metal layer 3, thereby altering the electrical properties of the chip bump and also changing its size. To ensure that the first metal layer 1 exposes the metal layer 2 after corrosion, the thickness of the first metal layer 1 is preferably less than the thicknesses of the second and third metal layers.

[0020] In this embodiment, the first metal layer 1 is made of gold, the middle metal layer 2 is made of copper, and the third metal layer is made of nickel. Gold has excellent conductivity, contact resistance stability, and high-frequency signal loss properties, which are well-suited for RFID. From the perspective of reading and writing signals, it has excellent performance and is also conducive to secondary binding. Nickel, on the other hand, has much poorer properties in these aspects (for RFID).

[0021] When gold is used as the outermost layer of a multi-layered metal bump, its limited thickness means that slight damage occurs when strong acid is used to "wash away" the original tag antenna residue. This damage creates "voids" in certain areas, exposing the inner copper layer to the air. Exposed copper forms an insulating layer, CuO or Cu2O, both of which have poor conductivity and are unsuitable for RFID, causing significant signal attenuation. This results in a significant decrease in the electrical performance of the re-bonded RFID chip, or even a complete "unreadable" situation. Ultimately, this greatly reduces the possibility of re-bonding and reusing the RFID chip. Therefore, users can visually observe changes in RFID performance to determine if the chip has been transferred and reused. In other embodiments, the copper layer can be placed on a third metal layer, with the first metal layer being gold and the second metal layer being made of a material that can be "washed away" along with the gold layer. This embodiment does not impose such restrictions, thus exposing the copper layer.

[0022] When gold is used as the outermost layer of multi-layered metal bumps, its limited thickness means that slight damage occurs when strong acid is used to remove the original tag antenna residue. This damage creates voids in certain areas, exposing the inner copper layer to air and causing oxidation. Consequently, the electrical performance of the re-bonded RFID chip deteriorates significantly, or it may even become unreadable. Ultimately, this greatly reduces the possibility of re-bonding and reusing the RFID chip. Therefore, users can visually observe changes in RFID performance to determine if it has been transferred and reused.

[0023] The significant advantage of this invention is that by using a multi-layer PAD production method, the yield of chips for secondary use is greatly reduced. After the outermost metal is corroded, the inner metal is easily oxidized or its conductivity (or high-frequency performance) is reduced, which greatly reduces the yield of reuse and increases the difficulty of reuse.

[0024] Example 2 like Figure 2As shown, this embodiment provides an RFID chip bump structure, which is based on Embodiment 1, but with a three-layer arc-shaped bump structure, including: a first metal layer 1, a second metal layer 2, and a third metal layer 3. This embodiment uses multiple metal bumpings without increasing the volume compared to traditional bump structures, and the electrical properties of each metal are different. The lower surface of the third metal layer 3 is electrically connected to the surface of the RFID chip, the second metal layer 2 is connected to the upper surface of the third metal layer 3, and the first metal layer 1 is connected to the upper surface of the second metal layer 2. When the first metal layer 1 is cleaned with an acidic solution, it can be corroded, exposing the second metal layer 2; or, the first metal layer 1 and the second metal layer 2 can be corroded when cleaned with an acidic solution, exposing the third metal layer 3. Therefore, the change in the bump structure leads to a change in the electrical properties of the bump structure, including: the exposed metal layers are easily oxidized, resulting in reduced conductivity or reduced high-frequency performance. Similarly, the first metal layer 1 is made of gold, the middle metal layer 2 is made of copper, and the third metal layer is made of nickel.

[0025] In other embodiments, the RFID chip bump structure can be a two-layer structure, such as copper or gold, or a multi-layer structure, such as four or more layers. This invention does not limit this.

[0026] Example 3 This embodiment provides an RFID chip, including the RFID chip bump structure of embodiment 1 or embodiment 2 above, wherein the bottommost metal layer of the multilayer metal layer of the RFID chip bump structure is electrically connected to the surface of the RFID chip.

[0027] The aforementioned RFID chip is used to construct an RFID tag. The RFID tag includes an RFID chip and an antenna. The antenna is electrically connected to the topmost metal layer of the multi-layered metal structure of the RFID chip.

[0028] When the RFID chip is removed from the RFID tag and reattached, it is generally necessary to first wash away the residual antenna adhering to the original bonding point (PAD) (usually by acid washing). At this time, the outermost gold layer will be slightly corroded, resulting in voids or partial defects, which will lead to the exposure and oxidation of the copper layer. Since the conductivity and high-frequency signal loss of the middle or inner layers are worse than gold, the performance of the tag after secondary processing will be greatly reduced, or even no feedback will be possible.

[0029] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "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 application 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 application.

[0030] The specific embodiments of this utility model have been described above. It should be understood that this utility model is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the substantive content of this utility model. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. An RFID chip bump structure, characterized in that, Includes multiple layers of metal that are electrically connected and stacked sequentially; The electrical properties of the multiple metal layers are different; After at least one of the multi-layer metal layers is damaged in the direction from farthest to near the RFID chip, the internal metal layers are partially or completely exposed, thereby changing the overall electrical performance of the RFID chip bump structure.

2. The RFID chip bump structure according to claim 1, characterized in that, Among the multi-layered metal structures, the metal layer furthest from the RFID chip is the gold layer.

3. The RFID chip bump structure according to claim 1 or 2, characterized in that, The multilayer metal layer has a three-layer structure, including: a first metal layer, a second metal layer, and a third metal layer; The lower surface of the third metal layer is used for surface electrical connection with the RFID chip, the second metal layer is connected to the upper surface of the third metal layer, and the first metal layer is connected to the upper surface of the second metal layer; The second metal layer is partially or completely exposed after the first metal layer is damaged; or, the third metal layer is partially or completely exposed after the first metal layer and the second metal layer are damaged.

4. The RFID chip bump structure according to claim 3, characterized in that, When the second metal layer is partially or completely exposed after the first metal layer is damaged, the second metal layer is a copper layer and the third metal layer is a nickel layer.

5. The RFID chip bump structure according to claim 3, characterized in that, When the third metal layer is partially or completely exposed after the first metal layer and the second metal layer are damaged, the third metal layer is a copper layer.

6. The RFID chip bump structure according to claim 1, characterized in that, The chip bump structure has a multi-layer planar structure.

7. The RFID chip bump structure according to claim 1, characterized in that, The chip bump structure is a multi-layered arc-shaped bump structure.

8. The RFID chip bump structure according to claim 1, characterized in that, The reduction in electrical performance includes: reduced conductivity or reduced high-frequency performance.

9. An RFID chip, characterized in that, The RFID chip bump structure includes the RFID chip bump structure according to any one of claims 1-8, wherein the metal layer of the multilayer metal layer of the RFID chip bump structure that is closest to the RFID chip is electrically connected to the surface of the RFID chip.

10. An RFID tag, characterized in that, The device includes the RFID chip and antenna as described in claim 9, wherein the antenna is electrically connected to the metal layer furthest from the RFID chip in the multilayer metal layers of the RFID chip bump structure.

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