Anti-sulfurization ultra-low resistance chip resistor structure

Abstract

This utility model relates to the field of resistive component technology, and more particularly to a sulfur-resistant ultra-low resistance chip resistor structure. It includes a substrate, a front electrode disposed on the upper surface of the substrate, a back electrode disposed on the lower surface of the substrate, a resistive layer printed between the front electrodes, a first protective layer, a second protective layer, and a third protective layer sequentially covering the outside of the resistive layer, and side internal electrodes disposed at both ends of the substrate. Both the front and back electrodes are made of silver-palladium paste, and the side internal electrodes, the front electrode, and the back electrode are all covered with protective layers. The beneficial effects of this utility model are: the use of silver-palladium paste for the front electrode reduces the possibility of a chemical reaction between silver and sulfur; the three-layer plating structure of the protective layer results in lower impedance, enhanced conductivity and corrosion resistance, and solves the problem of sulfide corrosion in existing chip resistors.

Description

Technical Field

[0001] This utility model relates to the field of resistor components technology, and in particular to an anti-sulfurization ultra-low resistance chip resistor structure. Background Technology

[0002] Surface mount resistors are important electronic components widely used in various electronic devices, playing a crucial role, especially in circuits requiring high precision and reliability. However, in real-world environments, particularly harsh environments with high sulfide content, traditional surface mount resistors are susceptible to the effects of sulfides in the air, leading to performance degradation or even failure.

[0003] In the prior art, the patent with authorization announcement number CN2023211249968—thick film chip resistor with aluminum paste anti-sulfurization—discloses a specific structure. The front electrode of this chip resistor is usually made of silver paste material. However, the silver element in the silver paste readily reacts with sulfur in the air to form silver sulfide, thereby affecting the conductivity and reliability of the resistor. This sulfidation phenomenon not only shortens the service life of the resistor but also limits its application range in harsh environments.

[0004] Therefore, it is necessary to design an anti-sulfurization ultra-low resistance chip resistor structure to solve the above problems. Utility Model Content

[0005] The purpose of this invention is to provide an anti-sulfurization ultra-low resistance chip resistor structure to overcome the above-mentioned shortcomings of the existing technology.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A sulfur-resistant ultra-low resistance patch resistor structure includes a substrate, a front electrode disposed on the upper surface of the substrate, a back electrode disposed on the lower surface of the substrate, a resistive layer printed between the front electrodes, a first protective layer, a second protective layer and a third protective layer sequentially covering the outside of the resistive layer, and side internal electrodes disposed at both ends of the substrate. The front electrode and the back electrode are both made of silver-palladium paste and are formed by screen printing on the upper and lower surfaces of the substrate, respectively. The side internal electrode is used to connect the front electrode and the back electrode to form a complete current path. The side internal electrode, the front electrode and the back electrode are all wrapped with a protective layer. The protective layer includes a copper plating layer, a nickel plating layer and a tin plating layer arranged sequentially from the inside to the outside.

[0007] Preferably, the substrate is made of alumina ceramic material with a thickness ranging from 0.5 mm to 1.0 mm.

[0008] Preferably, the resistive layer is made of ruthenium oxide and is printed between the front electrodes by screen printing, with a thickness ranging from 5 μm to 15 μm.

[0009] Preferably, the resistance layer is precisely adjusted using laser trimming technology.

[0010] Preferably, the first protective layer is made of glass and covers the outside of the resistive layer, completely encapsulating the resistive layer and part of the front electrode. The second protective layer is made of resin and is coated on the outside of the first protective layer. The third protective layer is also made of resin and is coated on the outside of the second protective layer, completely encapsulating the second protective layer.

[0011] Preferably, the copper plating layer is in direct contact with the front electrode and the back electrode.

[0012] Preferably, the nickel plating layer covers the outside of the copper plating layer, and the tin plating layer covers the outside of the nickel plating layer.

[0013] Preferably, stepped limiting grooves are provided at both ends of the substrate.

[0014] Preferably, a character identification layer is provided on the outside of the third protective layer.

[0015] The beneficial effects of this utility model are: this technical solution forms multiple barriers by setting up multiple protective layers, which effectively isolates the external environment from the corrosion of the resistive layer and the electrode; The front electrode uses silver-palladium paste instead of traditional silver paste, which reduces the possibility of silver reacting chemically with sulfur. By wrapping a protective layer around the inner side electrodes at both ends, the front electrode, and the outer side of the back electrode, the three-layer plating structure of the protective layer has lower impedance, enhanced conductivity and corrosion resistance, and solves the problem of surface mount resistors being easily corroded by sulfides in the prior art. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view of the structure of an anti-sulfurization ultra-low resistance chip resistor according to this utility model. In the figure: 1. Substrate; 2. Front electrode; 3. Back electrode; 4. Resistive layer; 5. First protective layer; 6. Second protective layer; 7. Third protective layer; 8. Side internal electrode; 9. Character identification layer; 13. Limiting groove; 81. Copper plating layer; 82. Nickel plating layer; 83. Tin plating layer. Detailed Implementation

[0017] Reference Figure 1A sulfur-resistant ultra-low resistance patch resistor structure includes a substrate 1, a front electrode 2 disposed on the upper surface of the substrate 1, a back electrode 3 disposed on the lower surface of the substrate 1, a resistor layer 4 printed between the front electrodes 2, a first protective layer 5, a second protective layer 6 and a third protective layer 7 sequentially covering the outside of the resistor layer, and side internal electrodes 8 disposed at both ends of the substrate 1.

[0018] The substrate 1 is made of alumina ceramic material with a thickness ranging from 0.5 mm to 1.0 mm. A front electrode 2 is formed on the upper surface of the substrate 1 using a screen printing process, and a back electrode 3 is formed on the lower surface of the substrate 1 using the same screen printing process. The front electrode 2 and the back electrode 3 are located on the upper and lower surfaces of the substrate 1, respectively, and are isolated from each other by the substrate 1. The main component of the front electrode 2 is silver-palladium paste, with a thickness ranging from 10 μm to 20 μm; the main component of the back electrode 3 is silver paste, with a thickness ranging from 10 μm to 20 μm.

[0019] The resistive layer 4 is made of ruthenium oxide and is printed between the front electrodes 2 using a screen printing process. Its thickness ranges from 5 μm to 15 μm. The resistive layer 4 achieves precise adjustment of its resistance value through laser trimming technology to meet the needs of different application scenarios.

[0020] The first protective layer 5 is made of glass and covers the outside of the resistive layer 4. It completely covers the resistive layer 4 and part of the front electrode 2, and its thickness ranges from 15μm to 30μm.

[0021] The second protective layer 6 is made of resin and is coated on the outside of the first protective layer 5. Its two ends are in contact with the front electrode 2 and completely cover the first protective layer 5. The thickness ranges from 20μm to 40μm. The second protective layer 6 is filled onto the first protective layer 5 through a coating process, thereby enhancing the bonding force between the second protective layer 6 and the first protective layer 5.

[0022] The third protective layer 7 is also made of resin material, coated on the outside of the second protective layer 6 and completely covering the second protective layer 6, with a thickness ranging from 25μm to 50μm.

[0023] The resistor's resistance to sulfidation is further enhanced by a multi-layered protective design. The first protective layer 5 is made of glass, with its ends embedded around the outer periphery of the resistive layer 4, forming a tight outer layer that effectively isolates the resistive layer from external environmental corrosion. The surface of the first protective layer 5 not only increases the bonding surface between it and the second protective layer 6 but also provides area for subsequent coating processes. The second protective layer 6 is made of resin and is firmly bonded to the first protective layer 5. The surface of the second protective layer 6, after bonding with the third protective layer 7, forms multiple protective barriers. This layer-by-layer design significantly improves the reliability of the resistor in harsh environments.

[0024] The side internal electrodes 8 are disposed on both end faces of the substrate 1, serving to connect the front electrode 2 and the back electrode 3, forming a complete current path. The outer sides of the side internal electrodes 8, the front electrode 2, and the back electrode 3 are all covered with a protective layer, which includes a copper plating layer 81, a nickel plating layer 82, and a tin plating layer 83 arranged sequentially from the inside out. The copper plating layer is in direct contact with the front electrode 2 and the back electrode 3, with a thickness ranging from 10 μm to 30 μm; the nickel plating layer covers the outer side of the copper plating layer, with a thickness ranging from 5 μm to 15 μm; and the tin plating layer covers the outer side of the nickel plating layer, with a thickness ranging from 10 μm to 25 μm.

[0025] The substrate 1 has stepped limiting grooves 13 at both ends, with a depth ranging from 10 μm to 20 μm and a width ranging from 0.2 mm to 0.3 mm. The side internal electrode 8 is embedded in the limiting groove 13, thereby enhancing the bonding strength between the side internal electrode 8 and the substrate 1.

[0026] The back electrode 3, the front electrode 2, and the outer side of the inner side electrode 8 are all coated with copper (i.e., can be considered as copper electrodes). Because ultra-low resistance (below 300mΩ) products have low resistance, copper has low impedance, making it a better conductor and improving the product's resistance. Furthermore, the copper electrodes completely enclose the front electrode, forming a structural anti-sulfur structure. By adding a copper electrode structure, and because the copper electrode has even lower impedance, the ultra-low resistance product achieves superior resistance.

[0027] A character identification layer 9 is provided on the outside of the third protective layer 7 to indicate the resistance value information of the resistor for easy identification and use.

[0028] The advantages of this utility model are that the design of setting multiple protective layers forms multiple barriers, which effectively isolates the external environment from the corrosion of the resistive layer and the electrodes. The front electrode uses silver-palladium paste instead of traditional silver paste, which reduces the possibility of silver reacting chemically with sulfur. By wrapping a protective layer around the inner side electrodes at both ends, the front electrode, and the outer side of the back electrode, the three-layer plating structure of the protective layer has lower impedance, enhanced conductivity and corrosion resistance, and solves the problem of surface mount resistors being easily corroded by sulfides in the prior art.

[0029] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A sulfur-resistant ultra-low resistance surface-mount resistor structure, comprising a substrate, a front electrode disposed on the upper surface of the substrate, a back electrode disposed on the lower surface of the substrate, a resistive layer printed between the front electrodes, a first protective layer, a second protective layer, and a third protective layer sequentially covering the outside of the resistive layer, and side internal electrodes disposed at both ends of the substrate, characterized in that: Both the front electrode and the back electrode are made of silver-palladium paste and are formed by screen printing on the upper and lower surfaces of the substrate, respectively. The side internal electrode is used to connect the front electrode and the back electrode to form a complete current path. The side internal electrode, the front electrode and the back electrode are all wrapped with a protective layer. The protective layer includes a copper plating layer, a nickel plating layer and a tin plating layer arranged sequentially from the inside to the outside.

2. The anti-sulfurization ultra-low resistance chip resistor structure according to claim 1, characterized in that: The substrate is made of alumina ceramic material with a thickness ranging from 0.5 mm to 1.0 mm.

3. The anti-sulfurization ultra-low resistance chip resistor structure according to claim 1, characterized in that: The resistive layer is made of ruthenium oxide and is printed between the front electrodes by screen printing. Its thickness ranges from 5 μm to 15 μm.

4. The anti-sulfurization ultra-low resistance chip resistor structure according to claim 3, characterized in that: The resistance layer achieves precise adjustment of its resistance value through laser trimming technology.

5. The anti-sulfurization ultra-low resistance chip resistor structure according to claim 4, characterized in that: The first protective layer is made of glass and covers the outside of the resistive layer, completely encapsulating the resistive layer and part of the front electrode. The second protective layer is made of resin and is coated on the outside of the first protective layer. The third protective layer is also made of resin and is coated on the outside of the second protective layer, completely encapsulating the second protective layer.

6. The anti-sulfurization ultra-low resistance chip resistor structure according to claim 1, characterized in that: The copper plating layer is in direct contact with the front electrode and the back electrode.

7. The anti-sulfurization ultra-low resistance chip resistor structure according to claim 1, characterized in that: The nickel plating layer covers the outside of the copper plating layer, and the tin plating layer covers the outside of the nickel plating layer.

8. The anti-sulfurization ultra-low resistance chip resistor structure according to claim 1, characterized in that: Stepped limiting grooves are provided at both ends of the substrate.

9. The anti-sulfurization ultra-low resistance chip resistor structure according to claim 1, characterized in that: A character identification layer is provided on the outside of the third protective layer.

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