High-temperature-resistant resistor and manufacturing method thereof

Abstract

The application discloses a high-temperature-resistant resistor and a manufacturing method thereof, which comprises a substrate, two groups of back electrodes, two groups of front electrodes, a resistor layer, a protective layer and two groups of side end electrodes; the resistor layer is connected with the inner sides of the two groups of front electrodes at two ends respectively, and the two ends of the resistor layer extend outward and cover the top surfaces of the two groups of front electrodes respectively; the length of the resistor layer is 2-4 times of the length of the front electrode, and the thickness of the resistor layer is 1.2-2 times of the thickness of the front electrode; the top surface of each group of front electrodes is provided with an auxiliary electrode layer at an outer end, and the inner side of the auxiliary electrode layer is connected with the outer side of the protective layer; printing of the auxiliary electrode layer is performed in the manufacturing process, and the resistor layer is subjected to radium cutting positioning groove setting. The application can improve the normal use of high power and high stability of the resistor in a high-temperature environment.

Description

Technical Field

[0001] This invention relates to a resistor, and more particularly to a high-temperature resistant resistor and its manufacturing method. Background Technology

[0002] Standard chip resistors are suitable for use in environments ranging from -55℃ to 155℃. They should be used at full power when the ambient temperature does not exceed 70℃. When the temperature exceeds 70℃, the load should be applied according to the derating curve (see figure). Figure 1 (As shown). If the chip resistor is used at full load at high temperatures without reducing its rated power, the resistance value will change significantly and become unstable after a period of use, making it difficult to meet the requirements for stable high-temperature load life. Eighty pieces of standard 0603 type chip resistors with a Life full-load power critical value of 45K3 (0.125W) were used. After three reflow soldering pretreatments, the chip resistors were soldered onto a high-temperature resistant PCB board. Then, under an ambient temperature of 180℃ and a working voltage of 75V, continuous power was applied. Monitoring the dimensions at various time points revealed that the resistance value change rate became increasingly discrete over time. After continuous power-on for H hours, the measured resistance value change rate exceeded 2%. Summary of the Invention

[0003] The purpose of this invention is to provide a high-temperature resistant resistor and its manufacturing method. By using this structure and method, a high-power, highly stable high-temperature resistor can be manufactured in high-temperature environments, thereby improving its stability and extending its service life.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: a high-temperature resistant resistor, comprising:

[0005] substrate;

[0006] Two sets of back electrodes are symmetrically arranged on both sides of the bottom surface of the substrate;

[0007] Two sets of front electrodes are symmetrically arranged on both sides of the top surface of the substrate.

[0008] A resistive layer is disposed on the top surface of the substrate between the two sets of front electrodes;

[0009] A protective layer covers the outside of the resistive layer, and both ends of the resistive layer respectively cover the top surface of the front electrodes on both sides;

[0010] Two sets of side end electrodes are respectively sealed on both sides of the substrate.

[0011] The two ends of the resistive layer are respectively connected to the inner sides of the two front electrodes, and the two ends of the resistive layer extend outwards respectively, covering part of the top surface of the two sets of front electrodes; the length of the resistive layer is 2.5 times to 5 times the length of the front electrode, and the thickness of the resistive layer is 1.2 times to 2 times the thickness of the front electrode.

[0012] Each of the front electrodes has an auxiliary electrode layer at the outer end of its top surface, and the inner side of the auxiliary electrode layer is connected to the outer side of the protective layer.

[0013] In the above technical solution, the side electrode includes a vacuum-deposited layer and an electroplated layer covering the outside of the vacuum-deposited layer; the middle part of the vacuum-deposited layer covers the side wall of the substrate, the upper part of the vacuum-deposited layer covers the outer wall of the front electrode and the auxiliary electrode layer, and the upper part of the vacuum-deposited layer covers a portion of the top surface of the auxiliary electrode layer; the lower part of the vacuum-deposited layer covers the outer wall of the back electrode, and the lower part of the vacuum-deposited layer covers a portion of the bottom surface of the back electrode.

[0014] The electroplating layer completely covers the outside of the vacuum coating layer, the top of the electroplating layer covers the outer top surface of the auxiliary electrode layer, and the top of the electroplating layer covers the outer wall of the protective layer; the bottom of the electroplating layer completely covers the outside of the back electrode, and the bottom of the electroplating layer covers part of the bottom surface of the substrate.

[0015] In the above technical solution, the protective layer includes a first protective layer and a second protective layer. The first protective layer covers the outside of the resistive layer, and the second protective layer covers the outside of the first protective layer. The bottom ends of the first and second protective layers respectively cover a portion of the front surface of the two sets of front electrodes.

[0016] In the above technical solution, the substrate is a ceramic substrate, the first protective layer is a glass protective layer, and the second protective layer is a resin protective layer.

[0017] In the above technical solution, the middle part of the resistive layer has a square structure, and the top two ends of the resistive layer are respectively provided with outwardly extending portions. The bottom surface of each set of extension portions is connected to part of the top surface of a set of front electrodes. The width of the extension portion is greater than the width of the middle part of the resistive layer and the top width of the front electrode. The extension portion completely covers and wraps the front electrode in the width direction. The resistive layer and the extension portions on both sides form a dumbbell structure that is large at both ends and small in the middle.

[0018] In the above technical solution, the front side and the rear side of the resistor layer are respectively provided with a front laser-cut positioning groove and a rear laser-cut positioning groove. The front laser-cut positioning groove is located near the left extension, and the rear laser-cut positioning groove is located near the right extension.

[0019] To achieve the above objectives, the present invention employs a method for manufacturing a high-temperature resistant resistor, the steps of which are as follows:

[0020] ① Print the back electrode on the bottom surface of the substrate, then print the front electrode on the top surface of the substrate, and then sinter and solidify to solidify the back electrode and the front electrode on the substrate.

[0021] ② A resistive layer is printed on the top surface of the substrate, and then sintered and cured; during the resistive layer printing process, laser-cut positioning grooves are reserved.

[0022] ③ Print the first protective layer on the first resistive layer. After the first protective layer is printed, sinter and cure it.

[0023] ④ Based on the laser-cut positioning groove, the resistive layer is cut and adjusted using a laser trimming machine;

[0024] ⑤ Print a second protective layer on top of the first protective layer, and then print auxiliary electrode layers on both sides of the outer surface of the second protective layer and on top of each group of front electrodes;

[0025] ⑥Then the characters are printed on the outside of the second protective layer and then cured to cure the second protective layer, the auxiliary electrode layer and the characters. After curing, the appearance is inspected.

[0026] ⑦ Fold the above-mentioned substrate into a strip-shaped semi-finished product;

[0027] ⑧ Vacuum coating is applied to both sides of the strip-shaped semi-finished product in step ⑦ to achieve a vacuum coating layer on both sides of the strip-shaped semi-finished product.

[0028] ⑨ Fold the strip-shaped semi-finished product from step ⑧ into granular semi-finished product;

[0029] ⑩ Electroplating is performed on the two ends of the granular semi-finished product with vacuum coating layer in step ⑨ to complete the production of high temperature resistant resistor.

[0030] In the above technical solution, the front electrode, the back electrode, and the resistive layer are sintered and cured at 850°C; the first protective layer is sintered and cured at 620°C; and the second protective layer, the auxiliary electrode layer, and the character code are sintered and cured at 200°C.

[0031] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0032] 1. In this invention, by setting the size of the resistive layer and the front electrode, the length and width of the current path can be expanded, the power of the resistor can be increased, the influence of conductor diffusion can be weakened, and the stability of the resistor under high temperature power can be enhanced, so that when operating at full power at 180°C, the resistance value change rate is less than 0.1%, thus improving the stability of the resistor under high temperature conditions.

[0033] 2. This invention can reduce hot spot accumulation, enhance the heat dissipation and high temperature resistance of the resistor, and improve the high temperature performance and stability of the resistor;

[0034] 3. In this invention, the resistive layer is a streamlined dumbbell structure, which can increase the overlap between the resistive layer and the front electrode, strengthen the coverage and protection of the front electrode edge by the resistive layer, and weaken the diffusion of silver from the conductor edge to the resistive layer caused by the tip effect, etc.; secondly, it effectively increases the heat dissipation area while avoiding the in-cut phenomenon caused by excessively wide resistance in the laser-cut resistance correction area.

[0035] 4. The multiple laser cutting positioning grooves in this invention facilitate laser cutting positioning, reduce fluctuations between cutting batches, and increase the effective length of the current path, thereby reducing damage to the resistive layer caused by excessively long laser cutting kerfs.

[0036] 5. The resistor layer thickness in this invention is thicker than that in previous structures, which avoids hot spots caused by defects in resistor layer printing and reduces the local temperature of the resistor layer; secondly, it widens the current path to improve power and lifespan stability.

[0037] 6. In this invention, an auxiliary electrode layer is added to solve the problem of insufficient front terminals caused by the shortening of the front electrode and the extension of the resistor layer, thereby increasing the heat dissipation capacity and corrosion resistance of the resistor. Attached Figure Description

[0038] Figure 1 This is a derating curve of the chip resistance in the background technology;

[0039] Figure 2 This is a schematic diagram of the structure in Embodiment 1 of the present invention;

[0040] Figure 3 This is a top view of the resistive layer state in Embodiment 1 of the present invention (a state diagram of the front electrode and resistive layer after printing during the mass production of resistors).

[0041] Wherein: 1. Substrate; 2. Back electrode; 3. Front electrode; 4. Resistive layer; 5. Auxiliary electrode layer; 6. Vacuum coating layer; 7. Electroplating layer; 8. First protective layer; 9. Second protective layer; 10. Extension; 11. Front laser-cut positioning groove; 12. Rear laser-cut positioning groove. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0043] Example 1: See Figure 2 , 3 As shown, a high-temperature resistant resistor includes:

[0044] Substrate 1; wherein the top surface of the substrate is the front side and the bottom surface of the substrate is the back side.

[0045] Two sets of back electrodes 2 are symmetrically arranged on both sides of the bottom surface of the substrate;

[0046] Two sets of front electrodes 3 are symmetrically arranged on both sides of the top surface of the substrate;

[0047] A resistive layer 4 is disposed on the top surface of the substrate between the two sets of front electrodes;

[0048] A protective layer covers the outside of the resistive layer, and both ends of the resistive layer respectively cover the top surface of the front electrodes on both sides;

[0049] Two sets of side end electrodes, each set of which is sealed to both sides of the substrate, characterized in that:

[0050] The two ends of the resistive layer are respectively connected to the inner sides of the two front electrodes, and the two ends of the resistive layer extend outwards respectively, covering part of the top surface of the two sets of front electrodes; the length of the resistive layer is 2.5 times to 5 times the length of the front electrode, and the thickness of the resistive layer is 1.2 times to 2 times the thickness of the front electrode.

[0051] Each of the front electrodes has an auxiliary electrode layer 5 at the outer end of its top surface, and the inner side of the auxiliary electrode layer is connected to the outer side of the protective layer.

[0052] In this embodiment, the resistive layer is extended while the front electrode is shortened. This increases the length of the resistive layer, ensuring stable contact between the resistive layer and the front electrode while extending the effective resistance, thereby improving resistor utilization, increasing the heat dissipation area, and enhancing stability under high-temperature conditions. Furthermore, since shortening the front electrode and extending the resistive layer can lead to insufficient front terminals, the auxiliary electrode layers on both sides address this issue, further increasing the resistor's heat dissipation and corrosion resistance. Increasing the thickness of the resistive layer prevents hot spots caused by printing defects, reducing localized temperature and widening the current path, thus improving power and lifespan stability.

[0053] Simultaneously, increasing the length and thickness of the resistive layer serves two purposes. First, it reduces localized defects caused by an excessively thin resistive layer. High-temperature loads can easily create hot spots, altering or disrupting the local conductivity mechanism and leading to unstable resistance values, thus improving operational stability. Second, increasing the thickness and length of the resistive layer widens the current path, increasing the power handling capability of the resistor.

[0054] See Figure 2 As shown, the side electrode includes a vacuum-deposited layer 6 and an electroplated layer 7 covering the outside of the vacuum-deposited layer; the middle part of the vacuum-deposited layer covers the side wall of the substrate, the upper part of the vacuum-deposited layer covers the outer wall of the front electrode and the auxiliary electrode layer, and the upper part of the vacuum-deposited layer covers a portion of the top surface of the auxiliary electrode layer; the lower part of the vacuum-deposited layer covers the outer wall of the back electrode, and the lower part of the vacuum-deposited layer covers a portion of the bottom surface of the back electrode.

[0055] The electroplated layer completely covers the exterior of the vacuum-deposited layer. The top of the electroplated layer covers the outer top surface of the auxiliary electrode layer and also covers the outer wall of the protective layer. The bottom of the electroplated layer completely covers the exterior of the back electrode and also covers a portion of the bottom surface of the substrate. The vacuum-deposited layer is used to connect the front electrode and the back electrode.

[0056] In this embodiment, due to the provision of the auxiliary electrode layer, the vacuum coating layer and the electroplated layer will cover the outside of the auxiliary electrode layer, thus serving to connect and conduct electricity.

[0057] See Figure 2 As shown, the protective layer includes a first protective layer 8 and a second protective layer 9. The first protective layer covers the outside of the resistive layer, and the second protective layer covers the outside of the first protective layer. The bottom ends of the first and second protective layers respectively cover a portion of the front surface of the two sets of front electrodes.

[0058] The substrate is a ceramic substrate, the first protective layer is a glass protective layer, and the second protective layer is a resin protective layer.

[0059] The first and second protective layers protect and insulate the resistive layer. The resin protective layer uses a high-temperature resistant resin with excellent heat dissipation to enhance the resistor's high-temperature resistance and heat dissipation capabilities, increasing its stability under high-temperature conditions. The resin protective layer typically uses a resin material with a low coefficient of thermal expansion.

[0060] See Figure 2 , 3As shown, the middle part of the resistive layer has a square structure, and the top two ends of the resistive layer are respectively provided with outwardly extending portions 10. The bottom surface of each set of extension portions is connected to part of the top surface of a set of front electrodes. The width of the extension portion is greater than the width of the middle part of the resistive layer and the top width of the front electrode. The extension portion completely covers and wraps the front electrode in the width direction. The resistive layer and the extension portions on both sides form a dumbbell structure that is large at both ends and small in the middle.

[0061] In this embodiment, the width of the resistive layer is slightly larger than the width of the front electrode. Therefore, the width of the extension is also larger than the width of the front electrode, thus forming a dumbbell structure. The inner side of the extension is connected to the sidewall of the resistive layer with an arc-shaped surface. The dumbbell structure of the resistive layer design can increase the overlap between the resistive layer and the front electrode. First, it strengthens the coverage and protection of the inner edge of the front electrode by the resistive layer, reducing the diffusion of silver from the conductor edge to the resistive layer caused by the tip effect. Second, it effectively increases the heat dissipation area while avoiding the in-cut phenomenon caused by excessively wide resistance in the laser-cut resistance correction area.

[0062] The left and right sides of the resistive layer are the length directions of the resistive layer, and the front and back are the width directions of the resistive layer. The length of the extension is greater than the overlap length between the front electrode and the resistive layer, and the width direction exceeds the width of the front electrode by 50 to 100 micrometers.

[0063] See Figure 3 As shown, the resistor layer is provided with a front laser-cut positioning groove 11 and a rear laser-cut positioning groove 12 on the front and rear sides, respectively. The front laser-cut positioning groove is located near the left extension, and the rear laser-cut positioning groove is located near the right extension.

[0064] The front and rear laser-cut positioning grooves are located in the laser-cut area of ​​the resistor layer. By setting the corresponding laser-cut positioning grooves, it is possible to facilitate laser cutting positioning, reduce inter-batch fluctuations, increase the effective length of the current path, and reduce the damage to the resistor layer caused by excessively long laser cutting kerfs, so as to ensure the resistance effect.

[0065] Furthermore, by setting the laser-cut positioning groove, it is placed at the starting position of the resistor layer that needs to be laser-cut. The starting position of the laser-cut is designed as a hollow area. After the resistor layer is printed to the required thickness using the correspondingly designed resistor screen, the starting part that needs to be laser-cut will have the grooved substrate exposed, which facilitates laser-cut positioning and reduces the cutting length, thereby reducing damage to the resistor layer during the cutting process and ensuring the resistance effect.

[0066] To achieve the above objectives, the present invention employs a method for manufacturing a high-temperature resistant resistor, the steps of which are as follows:

[0067] ① Print the back electrode on the bottom surface of the substrate, then print the front electrode on the top surface of the substrate, and then sinter and solidify to solidify the back electrode and the front electrode on the substrate.

[0068] ② A resistive layer is printed on the top surface of the substrate. The middle of the resistive layer is set between the two sets of front electrodes, and the two sides of the resistive layer overlap and cover the inner ends of the two front electrodes respectively. Then, it is sintered and cured. During the resistive layer printing process, laser-cut positioning grooves are reserved.

[0069] ③ Print the first protective layer on the first resistive layer. After the first protective layer is printed, sinter and cure it.

[0070] ④ Based on the laser-cut positioning groove, the resistive layer is cut and adjusted using a laser trimming machine;

[0071] ⑤ Print a second protective layer on top of the first protective layer, and then print auxiliary electrode layers on both sides of the outer surface of the second protective layer and on top of each group of front electrodes;

[0072] ⑥Then the characters are printed on the outside of the second protective layer and then cured to cure the second protective layer, the auxiliary electrode layer and the characters. After curing, the appearance is inspected.

[0073] ⑦ Fold the above-mentioned substrate into a strip-shaped semi-finished product;

[0074] ⑧ Vacuum coating is applied to both sides of the strip-shaped semi-finished product in step ⑦ to achieve a vacuum coating layer on both sides of the strip-shaped semi-finished product.

[0075] ⑨ Fold the strip-shaped semi-finished product from step ⑧ into granular semi-finished product;

[0076] ⑩ Electroplating is performed on the two ends of the granular semi-finished product with vacuum coating layer in step ⑨ to complete the production of high temperature resistant resistor.

[0077] The front electrode, back electrode, and resistive layer are sintered and cured at 850°C; the first protective layer is sintered and cured at 620°C; and the second protective layer, auxiliary electrode layer, and character code are sintered and cured at 200°C.

[0078] The auxiliary electrode layer is made of a conductive and electroplatable material, which can enhance heat dissipation, block the invasion of sulfides, and has a good bonding force with the second protective layer and the front electrode.

[0079] In this invention, without the introduction of new materials, the resistor can operate and be used normally with high power and high stability in high-temperature environments, extending its service life, ensuring the stability of use, and improving its applicability.

Claims

1. A high-temperature-resistant resistor comprising: a substrate; two groups of back electrodes symmetrically arranged on two sides of the bottom surface of the substrate; two groups of front electrodes symmetrically arranged on two sides of the top surface of the substrate; a resistor layer arranged on the top surface of the substrate between the two groups of front electrodes; a protective layer covering the outside of the resistor layer; two groups of side end electrodes sealed on both sides of the substrate, characterized in that: the two ends of the resistor layer are connected to the inner sides of the two groups of front electrodes, the length of the resistor layer is 2.5 to 5 times the length of the front electrodes, and the thickness of the resistor layer is 1.2 to 2 times the thickness of the front electrodes; the top outer end of each group of front electrodes is provided with an auxiliary electrode layer, and the inner side of the auxiliary electrode layer is connected to the outer side of the protective layer; the middle part of the resistor layer is a square structure, the top ends of the resistor layer are respectively provided with outwardly extending extensions, the bottom surface of each group of extensions is connected to part of the top surface of a group of front electrodes, thereby covering part of the top surface of the front electrodes; the width of the extension is greater than the width of the middle part of the resistor layer and the width of the top part of the front electrode, and the extension completely covers the front electrode in the width direction, and the resistor and the two extensions form a dumbbell structure with large ends and a small middle part; the front and rear sides of the resistor are respectively provided with front and rear laser cutting positioning grooves, the front laser cutting positioning groove is arranged close to the left extension, and the rear laser cutting positioning groove is arranged close to the right extension.

2. The high temperature resistant resistor of claim 1, wherein: The side end electrode comprises a vacuum coating layer and an electroplated layer covering the outside of the vacuum coating layer; the middle part of the vacuum coating layer covers the side wall of the substrate, the upper part of the vacuum coating layer covers the outer wall of the front electrode and the auxiliary electrode layer, and part of the top surface of the auxiliary electrode layer is covered by the upper part of the vacuum coating layer; the lower part of the vacuum coating layer covers the outer wall of the back electrode, and part of the bottom surface of the back electrode is covered by the lower part of the vacuum coating layer; The electroplated layer completely covers the outside of the vacuum coating layer, the upper part of the electroplated layer covers the outer top surface of the auxiliary electrode layer, and the upper part of the electroplated layer covers the outer wall of the protective layer; the lower part of the electroplated layer completely covers the outside of the back electrode, and the lower part of the electroplated layer covers part of the bottom surface of the substrate.

3. The high temperature resistant resistor of claim 1, wherein: The protective layer comprises a first protective layer and a second protective layer, the first protective layer covers the outside of the resistor layer, the second protective layer covers the outside of the first protective layer, and the bottom of the two ends of the first and second protective layers is respectively covered on part of the front surface of the two groups of front electrodes.

4. The high temperature resistant resistor of claim 3, wherein: The substrate is a ceramic substrate, the first protective layer is a glass protective layer, and the second protective layer is a resin protective layer.

5. A method for manufacturing a high-temperature-resistant resistor, comprising the steps of: ① Print back electrode on the bottom surface of the substrate, then print front electrode on the top surface of the substrate, and then sinter and solidify to solidify the back electrode and the front electrode on the substrate; ② Print the resistance layer on the top surface of the substrate, and then sinter and solidify; During the printing of the resistance layer, a laser cutting positioning groove is reserved; ③ Print the first protective layer on the first resistance layer, and then sinter and solidify after the printing of the first protective layer is completed; ④ According to the laser cutting positioning groove, cut and adjust the resistance layer by using a laser laser resistance adjusting machine; ⑤ Print the second protective layer on the first protective layer, and then print the auxiliary electrode layer on the two sides of the second protective layer and above each group of front electrodes; ⑥ Then print the character code on the outside of the second protective layer, and then sinter and solidify to solidify the second protective layer, the auxiliary electrode layer and the character code, and then perform appearance inspection after the solidification is completed; ⑦ Fold the above substrate into a strip-shaped semi-finished product; ⑧ Perform vacuum plating on both sides of the strip-shaped semi-finished product of step ⑦ to realize vacuum plating on both sides of the strip-shaped semi-finished product; ⑨ Fold the strip-shaped semi-finished product in step ⑧ into a granular semi-finished product; ⑩ Make an electroplating layer on the two ends of the granular semi-finished product in step ⑨ which is provided with a vacuum plating layer, and complete the production of the high-temperature-resistant resistor.

6. The method of claim 5, wherein: The front electrode, the back electrode and the resistance layer are sintered and solidified at 850℃; the first protective layer is sintered and solidified at 620℃; and the second protective layer, the auxiliary electrode layer and the character code are sintered and solidified at 200℃.

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