Vehicle gauge thick film chip resistor

Abstract

The invention relates to the technical field of resistors, in particular to a vehicle gauge thick film chip resistor which comprises a substrate, electrode assemblies arranged on the two sides of the substrate, a tin plating layer and a nickel plating layer, the tin plating layer and the nickel plating layer are arranged on the outer sides of the electrode assemblies, each electrode assembly comprises a positive electrode, and the positive electrode comprises 0.5% of palladium; a resistive layer is arranged above the substrate, and a protective layer is arranged above the resistive layer; the protection layer is arranged to be two layers including a top protection layer and a bottom protection layer, the two side edges of the bottom protection layer are arranged on the upper side of the electrode assembly, the bottom protection layer comprises a radial step layer and a vertical step layer, the radial step layer is in a spiral sheet shape, the edge area of the radial step layer is made of titanium nitride, and the vertical step layer is made of titanium nitride. The transition area is made of titanium nitride and ruthenium dioxide, and the central area is made of ruthenium dioxide; the vertical step layer is in a grid shape. According to the invention, the palladium content is reduced, the cost is reduced, and the sulfuration resistance of the electrode is ensured through the double protection layers.

Description

Technical Field

[0001] The present invention relates to the technical field of resistors, and in particular to an automotive-grade thick-film chip resistor. Background Art

[0002] Thick film chip resistors are one of the most commonly used and mainstream types of surface mount resistors in modern electronic circuits. They are miniature rectangular electronic components made by printing and sintering special resistor paste on a ceramic substrate.

[0003] Patent publication number CN103632779B discloses a power thick-film resistor comprising a resistor substrate with inner electrodes and resistors printed on one side and a back electrode printed on the other. A heat-conducting plate is provided on the surface of the back electrode of the resistor substrate. The heat-conducting plate is a ceramic substrate with inner and outer heat-conducting plates fixedly mounted on the inner and outer surfaces, respectively. The inner heat-conducting plate is nickel-plated and welded to the back electrode of the resistor substrate in a face-to-face manner. The ceramic substrate, with heat-conducting plates welded on both its inner and outer surfaces, is welded to the surface of the back electrode of the resistor substrate to serve as the heat-conducting plate. Thermal deformation of the two-sided heat-conducting plates offsets each other, resulting in a substantially uniform thermal expansion coefficient between the heat-conducting plate and the resistor substrate. This resistor achieves higher resistance power within the same volume while maintaining stable performance and preventing thermal deformation.

[0004] Mixing palladium into the electrode material of thick film resistors, with the palladium content usually at 3%, is a key design to improve electrode reliability, especially for core requirements such as anti-sulfurization, migration inhibition, and sintering optimization. However, the cost of palladium is relatively high. In order to reduce costs, the protective layer needs to be optimized. Summary of the Invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art that the cost of palladium element is relatively high and the protective layer needs to be optimized in order to reduce the cost, and to propose an automotive-grade thick-film chip resistor.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: An automotive-grade thick-film chip resistor, comprising: a substrate, an electrode assembly disposed on both sides of the substrate, and a tin plating layer and a nickel plating layer disposed on the outside of the electrode assembly, wherein the electrode assembly includes a positive electrode containing 0.5% palladium; A resistance layer is provided above the substrate, and a protective layer is provided above the resistance layer; The protective layer is provided as a double layer, namely a top protective layer and a bottom protective layer, both sides of the bottom protective layer are provided on the upper side of the electrode assembly, the bottom protective layer includes a radial stepped layer and a vertical stepped layer, the radial stepped layer is in the shape of a spiral sheet, the edge area of ​​the radial stepped layer is made of titanium nitride, the transition area is made of titanium nitride and ruthenium dioxide, and the central area is made of ruthenium dioxide; The vertical step layer is in a grid shape and is arranged below the radial step layer. The vertical step layer is made of silver, and the grid is used to limit corrosion.

[0007] Preferably, the electrode assembly further includes two back electrodes and two side electrodes, the two positive electrodes are symmetrically arranged on both sides of the upper surface of the substrate, the two back electrodes are symmetrically arranged on both sides of the lower surface of the substrate, and the two side electrodes are symmetrically arranged on both sides of the substrate.

[0008] Preferably, the side electrodes are made of nickel plating, and the positive electrode and the back electrode are both made of silver.

[0009] Preferably, the top protective layer is an epoxy resin protective layer, the tin plating layer is arranged on the outside of the nickel plating layer, a card slot is provided inside the upper side of the nickel plating layer, both sides of the top protective layer extend to below the nickel plating layer, and the edges on both sides of the top protective layer protrude upward and are stuck inside the card slot.

[0010] Preferably, a self-repairing layer is provided between the bottom protection layer and the resistance layer, and the self-repairing layer is used to protect the side gap of the positive electrode.

[0011] Preferably, the self-repairing layer includes a buffer layer and two gap layers, the two gap layers are symmetrically arranged on both sides of the buffer layer, and the gap layers are L-shaped and are clamped on the top and side of the positive electrode.

[0012] Preferably, the buffer layer is a composite conductive phase layer made of ruthenium dioxide and silver, and a plurality of vertical holes are opened on the buffer layer, vertical carbon nanotubes are arranged inside the vertical holes, and the plurality of vertical carbon nanotubes form a buffer array.

[0013] Preferably, the gap layer is made of ruthenium dioxide, and the gap layer is provided with a micro cavity, and a corrosion inhibitor is provided inside the micro cavity.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. By setting two protective layers and structural design, the positive electrode's anti-sulfurization is guaranteed. The high-sulfur exposed area at the edge of the bottom protective layer is blocked with inert titanium nitride, the transition area is made of titanium nitride and ruthenium dioxide, and the central area is made of ruthenium dioxide to ensure precision. The spiral staircase can be conveniently painted. The radial step layer can reduce the volume while ensuring the same power. The silver grid of the vertical step layer reduces the hot spot temperature, reduces sulfur thermal activation corrosion, and limits local corrosion to a single step, avoiding overall failure. While reducing the palladium content and cost, the present invention ensures the electrode's anti-sulfurization through the double protective layer. 2. By clamping both sides of the top protective layer with the inside of the card slot, the resin material will expand during use, thereby strengthening the sealing between the top protective layer and the tin plating layer and the nickel plating layer, reducing the gap and enhancing the protection of the top protective layer; 3. A composite conductive layer made of ruthenium dioxide and silver is provided between the silver vertical step layer and the resistor layer to ensure electrical conductivity while ensuring the normal use of the vertical step layer and the resistor layer when sulfide occurs; 4. Multiple vertical carbon nanotubes are arranged on the buffer layer. The vertical carbon nanotubes are arranged in the gaps of the grid-type vertical step layer, playing the role of supplementing the buffer surface at the position where the buffering effect of the grid-type vertical step layer is lower, thereby ensuring the buffering effect of the entire protective layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the front structure of an automotive-grade thick-film chip resistor proposed by the present invention; Figure 2 This is a schematic diagram of the cross-sectional structure of an automotive-grade thick-film chip resistor proposed by the present invention; Figure 3 This is a schematic diagram of the bottom protective layer structure of an automotive-grade thick-film chip resistor proposed by the present invention; Figure 4 This is a schematic diagram of the radial stepped layer structure of an automotive-grade thick-film chip resistor proposed by the present invention; Figure 5 This is a schematic diagram of the internal structure of an automotive-grade thick-film chip resistor proposed by the present invention; Figure 6 This is a schematic diagram of the self-healing layer structure of an automotive-grade thick-film chip resistor proposed by the present invention; Figure 7 for Figure 2 Schematic diagram of the enlarged structure at point A in the middle.

[0016] In the figure: 1. Substrate; 2. Electrode assembly; 21. Positive electrode; 22. Back electrode; 23. Side electrode; 3. Resistive layer; 4. Top protective layer; 5. Bottom protective layer; 51. Radial step layer; 511. Edge region; 512. Transition region; 513. Center region; 52. Vertical step layer; 6. Self-healing layer; 61. Buffer layer; 62. Gap layer; 7. Vertical carbon nanotubes. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0018] The terms "upper", "lower", "left", "right", "middle" and "one" used in the present invention are only for the convenience of description and are not intended to limit the scope of the present invention. Changes or adjustments to their relative relationships should be regarded as within the scope of the present invention without substantially changing the technical content.

[0019] Reference Figure 1-Figure 7 A vehicle-grade thick-film chip resistor comprises: a substrate 1, an electrode assembly 2 disposed on both sides of the substrate 1, a tin plating layer and a nickel plating layer disposed on the outer side of the electrode assembly 2, the electrode assembly 2 comprising a positive electrode 21, and the positive electrode 21 comprising 0.5% palladium; A resistance layer 3 is provided above the substrate 1, and a protective layer is provided above the resistance layer 3; The protective layer is provided as a double layer, namely a top protective layer 4 and a bottom protective layer 5. Both sides of the bottom protective layer 5 are provided on the upper side of the electrode assembly 2. The bottom protective layer 5 includes a radial stepped layer 51 and a vertical stepped layer 52. The radial stepped layer 51 is in the shape of a spiral sheet. The edge region 511 of the radial stepped layer 51 is made of titanium nitride, the transition region 512 is made of titanium nitride and ruthenium dioxide, and the central region 513 is made of ruthenium dioxide. The vertical step layer 52 is in a grid shape and is disposed below the radial step layer 51 . The vertical step layer 52 is made of silver, and the grid is used to limit corrosion.

[0020] In the embodiment of the above technical solution, since the use of palladium is reduced in the positive electrode 21, the anti-sulfurization ability of the motor is reduced while the cost is reduced. By setting two protective layers and structural design, the anti-sulfurization of the positive electrode 21 is guaranteed. The high-sulfur exposed area at the edge of the bottom protective layer is blocked with inert titanium nitride, the transition area is made of titanium nitride and ruthenium dioxide, and the central area 513 is made of ruthenium dioxide to ensure accuracy. The spiral steps can be easily painted. The radial step layer 51 can reduce the volume while ensuring the same power. The silver grid of the vertical step layer 52 reduces the hot spot temperature, reduces sulfur thermal activation corrosion, and limits local corrosion to a single step to avoid overall failure. While reducing the palladium content and reducing costs, the present invention ensures the anti-sulfurization of the electrode through a double-layer protective layer.

[0021] The preferred technical solution in this embodiment is: Reference Figure 2 The electrode assembly 2 further includes two back electrodes 22 and two side electrodes 23. The two positive electrodes 21 are symmetrically arranged on both sides of the upper surface of the substrate 1, the two back electrodes 22 are symmetrically arranged on both sides of the lower surface of the substrate 1, and the two side electrodes 23 are symmetrically arranged on both sides of the substrate 1. The side electrodes 23 are made of nickel plating, and the positive electrode 21 and the back electrode 22 are both made of silver.

[0022] The resistor layer 3 is covered with a positive electrode 21 and a back electrode 22 at its ends, respectively. These electrodes are typically silver or copper and are typically used for soldering. The outermost side electrode 23 is typically plated with nickel and tin / tin-lead alloy to prevent silver migration while ensuring solderability.

[0023] Reference Figure 2 The top protective layer 4 is an epoxy resin protective layer, the tin plating layer is arranged on the outside of the nickel plating layer, a card slot is arranged inside the upper side of the nickel plating layer, and the two sides of the top protective layer 4 extend to the bottom of the nickel plating layer, and the edges on both sides of the top protective layer 4 protrude upward and are stuck inside the card slot.

[0024] The epoxy resin protective layer is located on the top, and the top protective layer 4 is in direct contact with the outside. The resin layer can play a buffering role to avoid mechanical damage, while blocking moisture penetration and dust, protecting the inside of the resistor; However, since the top protective layer 4 is made of different materials from the outer tin plating and nickel plating, there will be a gap between the top protective layer 4 and the outer tin plating and nickel plating, which will cause external sulfur to enter the resistor and cause sulfurization of the internal components of the resistor.

[0025] By clamping the two sides of the top protective layer 4 with the inside of the card slot, the resin material will expand during use, thereby strengthening the sealing between the top protective layer 4 and the tin plating layer and the nickel plating layer, reducing the gap and enhancing the protection of the top protective layer 4.

[0026] Reference Figure 5-6 A self-repairing layer 6 is provided between the bottom protective layer 5 and the resistance layer 3, and the self-repairing layer 6 is used to protect the side gap of the positive electrode 21; The self-repairing layer 6 includes a buffer layer 61 and two gap layers 62. The two gap layers 62 are symmetrically arranged on both sides of the buffer layer 61. The gap layers 62 are L-shaped and are clamped on the top and side of the positive electrode 21. The buffer layer 61 is a composite conductive layer made of ruthenium dioxide and silver, and a plurality of vertical holes are opened on the buffer layer 61. Vertical carbon nanotubes 7 are arranged inside the vertical holes. The plurality of vertical carbon nanotubes 7 form a buffer array. The gap layer 62 is made of ruthenium dioxide, and a micro cavity is provided in the gap layer 62 , and a corrosion inhibitor is provided inside the micro cavity.

[0027] Providing a composite conductive phase layer made of ruthenium dioxide and silver between the silver vertical step layer 52 and the resistor layer 3 can ensure electrical conductivity while ensuring normal use of the vertical step layer 52 and the resistor layer 3 when sulfidation occurs.

[0028] The self-healing layer 6 is a structure that improves the resistance of the resistor to sulfidation. It significantly improves the life of the device by dynamically repairing damage when corrosion occurs. When corrosion or mechanical damage causes the microcavity to rupture, the corrosion inhibitor flows out and polymerizes and diffuses to the damaged area to repair the ruptured area, thereby ensuring anti-sulfidation.

[0029] Liquid corrosion inhibitors are usually silicone prepolymers or ionic liquids, while solid corrosion inhibitors such as zincate or sodium molybdate form a barrier layer when the corrosion inhibitor comes into contact with sulfide, thereby providing further protection.

[0030] A plurality of vertical carbon nanotubes 7 are arranged on the buffer layer 61. The vertical carbon nanotubes 7 are arranged in the gaps of the grid-type vertical step layer 52, and play the role of supplementing the buffer surface at the position where the buffering effect of the grid-type vertical step layer 52 is lower, thereby ensuring the buffering effect of the entire protective layer.

[0031] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. An automotive-grade thick-film chip resistor, comprising: A substrate (1), an electrode assembly (2) arranged on both sides of the substrate (1), and a tin plating layer and a nickel plating layer arranged on the outside of the electrode assembly (2), characterized in that the electrode assembly (2) includes a positive electrode (21), and the positive electrode (21) includes 0.5% palladium; A resistance layer (3) is provided above the substrate (1), and a protective layer is provided above the resistance layer (3); The protective layer is provided as a double layer, namely a top protective layer (4) and a bottom protective layer (5), both sides of the bottom protective layer (5) are provided on the upper side of the electrode assembly (2), the bottom protective layer (5) comprises a radial step layer (51) and a vertical step layer (52), the radial step layer (51) is in the shape of a spiral sheet, the edge region (511) of the radial step layer (51) is made of titanium nitride, the transition region (512) is made of titanium nitride and ruthenium dioxide, and the central region (513) is made of ruthenium dioxide; The vertical step layer (52) is in a grid shape and is arranged below the radial step layer (51); the vertical step layer (52) is made of silver, and the grid is used to limit corrosion.

2. The automotive grade thick film chip resistor according to claim 1, characterized in that: The electrode assembly (2) further comprises two back electrodes (22) and two side electrodes (23), wherein the two positive electrodes (21) are symmetrically arranged on both sides of the upper surface of the substrate (1), the two back electrodes (22) are symmetrically arranged on both sides of the lower surface of the substrate (1), and the two side electrodes (23) are symmetrically arranged on both sides of the substrate (1).

3. The automotive grade thick film chip resistor according to claim 2, characterized in that: The side electrode (23) is made of nickel plating, and the positive electrode (21) and the back electrode (22) are both made of silver.

4. The automotive grade thick film chip resistor according to claim 1, characterized in that: The top protective layer (4) is an epoxy resin protective layer, the tin plating layer is arranged on the outside of the nickel plating layer, a card slot is arranged inside the upper side of the nickel plating layer, both sides of the top protective layer (4) extend to below the nickel plating layer, and the edges of both sides of the top protective layer (4) are raised upwards and are stuck inside the card slot.

5. The automotive grade thick film chip resistor according to claim 1, characterized in that: A self-repairing layer (6) is provided between the bottom protective layer (5) and the resistance layer (3), and the self-repairing layer (6) is used to protect the side gap of the positive electrode (21).

6. The automotive-grade thick film chip resistor according to claim 5, characterized in that: The self-repairing layer (6) comprises a buffer layer (61) and two gap layers (62), wherein the two gap layers (62) are symmetrically arranged on both sides of the buffer layer (61), and the gap layers (62) are L-shaped and are clamped on the top and side of the positive electrode (21).

7. The automotive-grade thick film chip resistor according to claim 6, characterized in that: The buffer layer (61) is a composite conductive phase layer made of ruthenium dioxide and silver, and a plurality of vertical holes are opened on the buffer layer (61), vertical carbon nanotubes (7) are arranged inside the vertical holes, and the plurality of vertical carbon nanotubes (7) form a buffer array.

8. The automotive-grade thick film chip resistor according to claim 6, characterized in that: The gap layer (62) is made of ruthenium dioxide, and the gap layer (62) is provided with a micro cavity, and a corrosion inhibitor is provided inside the micro cavity.

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