Current sense resistor and method of manufacturing the same

Abstract

A current sensing resistor and a manufacturing method thereof are disclosed. The manufacturing method provides a composite material. Then, a portion of an alloy substrate of the composite material is removed along a first direction to form a first groove. Next, another portion of the alloy substrate of the composite material is removed along a second direction to form a second groove, and further another portion of the alloy substrate of the composite material is removed along the first direction to form the current sensing resistor. By the method of the present application, a current sensing resistor with small size and extremely low temperature coefficient of resistance can be quickly manufactured.

Description

Technical Field

[0001] This invention relates to a current sensing resistor and a method for manufacturing the same, and in particular to a small-sized current sensing resistor with an extremely low temperature coefficient of resistance and a method for manufacturing the same. Background Technology

[0002] The typical manufacturing process for current sensing resistors involves multiple bonding processes, pressure dry film processing, wet film printing, photolithography, and film removal, making the overall process complex and time-consuming. As electronic components shrink in size, current sensing resistors are also trending towards miniaturization, while still needing to maintain excellent, extremely low resistivity characteristics even at large sizes. However, these complex processes are insufficient for manufacturing small-sized current sensing resistors and cannot meet these requirements. Furthermore, as product size decreases, the electrodes are susceptible to underdevelopment or overdevelopment, leading to poor soldering, resistance drift due to electrode interface issues during reflow soldering, or burnout due to insufficient current withstand capability after prolonged exposure to high currents, among other quality problems.

[0003] In view of this, there is an urgent need to provide a current sensing resistor and its manufacturing method to improve the shortcomings of existing current sensing resistor manufacturing methods. Summary of the Invention

[0004] One aspect of the present invention provides a method for manufacturing a current sensing resistor, wherein the method can quickly and efficiently form small-sized electrodes to meet application requirements.

[0005] Another aspect of the present invention is to provide a small-sized current sensing resistor with an extremely low temperature coefficient of resistance, which is manufactured by the aforementioned method.

[0006] According to another aspect of the present invention, a method for manufacturing a current-sensing resistor is provided. This method includes: providing a composite material comprising an insulating layer and an alloy substrate disposed on the insulating layer, the alloy substrate having a temperature coefficient of resistance of less than 50 ppm / °C; removing a portion of the alloy substrate of the composite material along a first direction to form a plurality of first trenches on the upper surface of the alloy substrate; removing another portion of the alloy substrate of the composite material along a second direction to form a plurality of second trenches, wherein these second trenches expose the insulating layer, and the second direction is not parallel to the first direction; and after forming the second trenches, removing another portion of the alloy substrate along the first direction to form a plurality of third trenches and a plurality of resistive elements, wherein these third trenches expose the insulating layer, and each of the third trenches is disposed between adjacent first trenches, and the resistive elements are arranged in an array on the insulating layer.

[0007] According to some embodiments of the present invention, the aforementioned alloy substrate has a thickness of less than 0.5 mm.

[0008] According to some embodiments of the present invention, the aforementioned alloy substrate comprises copper manganese tin or copper manganese nickel.

[0009] According to some embodiments of the invention, after forming the aforementioned resistive element, the method further includes removing a portion of the bottom surface of each of the first trenches.

[0010] According to an embodiment of the present invention, the aspect ratio of each of the aforementioned first trenches is 0.1 to 0.35.

[0011] According to an embodiment of the present invention, the aforementioned first direction is perpendicular to the second direction.

[0012] According to an embodiment of the present invention, after forming the aforementioned third trench, the method further includes filling each first trench with a protective material to form a protective layer.

[0013] According to an embodiment of the present invention, after forming the aforementioned protective layer, the method further includes separating each resistive element to obtain a plurality of current sensing resistors.

[0014] According to some embodiments of the present invention, the aforementioned manufacturing method further includes forming an alloy layer on each current sensing resistor.

[0015] According to another aspect of the present invention, a current sensing resistor is provided. This current sensing resistor is manufactured by the aforementioned manufacturing method, and the long side of the current sensing resistor is less than 1.8 mm and the current sensing resistor has a resistance temperature coefficient of less than 50 ppm / ℃.

[0016] The current sensing resistor and its manufacturing method of the present invention remove material from the same alloy substrate along a first direction and a second direction to quickly and efficiently form a small-sized current sensing resistor with an extremely low temperature coefficient of resistance. Furthermore, since the current sensing resistor of the present invention is processed from the same alloy substrate, photolithography is not required, and soldering is not necessary to combine the electrodes and resistors. Therefore, the manufacturing method of the current sensing resistor of the present invention avoids the defects of insufficient or excessive development in existing photolithography techniques, and does not produce poor solderability due to electrode defects, or quality problems such as resistance shift after reflow. Accordingly, the current sensing resistor of the present invention has excellent characteristics such as a low temperature coefficient of resistance, no solder defects, and complete electrode patterns. Attached Figure Description

[0017] To gain a more complete understanding of the embodiments and advantages of the present invention, please refer to the following description and corresponding drawings. It must be emphasized that the various features are not depicted to scale and are for illustrative purposes only. The relevant drawings are explained below.

[0018] Figure 1This is a schematic flowchart illustrating a method for manufacturing a current sensing resistor according to some embodiments of the present invention.

[0019] Figures 2A to 2D The figures are respectively drawn according to the present invention Figure 1 A three-dimensional view of the current sensing resistors manufactured at each stage.

[0020] Figure 3A To draw along Figure 2D A cross-sectional view of the current sensing resistor cut by line segment A-A'.

[0021] Figure 3B A cross-sectional view of a current sensing resistor according to some embodiments of the present invention is shown. Detailed Implementation

[0022] The manufacture and use of embodiments of the present invention are discussed in detail below. However, it will be understood that the embodiments provide many applicable inventive concepts that can be implemented in a wide variety of specific contexts. The specific embodiments discussed are for illustrative purposes only and are not intended to limit the scope of the invention.

[0023] Please refer to the following at the same time Figure 1 and Figures 2A to 2D ,in Figure 1 To illustrate a process flow diagram of a method for manufacturing a current sensing resistor according to some embodiments of the present invention, Figures 2A to 2D The drawing is based on Figure 1 A perspective view of the current-sensing resistor manufactured at each stage. As shown in operation 110, manufacturing method 100 first provides a composite material 200. The composite material 200 includes an insulating layer 210 and an alloy substrate 220, wherein the alloy substrate 220 is disposed on the insulating layer 210. In some embodiments, an insulating material (such as aluminum oxide paste) or other suitable insulating material is coated on the bottom surface of the alloy substrate 220 by a printing process or a similar coating process to form the insulating layer 210. In other embodiments, an alloy material is plated on the top surface of the insulating layer 210 by a plating process or a similar process to form the alloy substrate 220. In other embodiments, the insulating layer 210 and the alloy substrate 220 are joined by an adhesive or other suitable fixing method to ensure that the alloy substrate 220 is tightly attached to the insulating layer 210 to facilitate subsequent processing.

[0024] The insulating layer 210 is not particularly limited; it only needs to have electrical insulating properties and be able to support the alloy substrate 220. The alloy substrate 220 has a temperature coefficient of resistance (TCR) of less than 50 ppm / ℃. Due to photolithography and welding techniques, when the size is miniaturized, its dimensions are difficult to control, and welding technology can no longer meet the miniaturization requirements, resulting in a TCR higher than 50 ppm / ℃. Therefore, this is detrimental to the stable operation of the resistive element over a wide operating temperature range. In some embodiments, the thickness of the alloy substrate 220 is less than 0.5 mm to meet the requirements of small-size applications. In some embodiments, the alloy substrate 220 includes, but is not limited to, copper manganese tin (CuMnSn), copper manganese nickel (CuMnNi), other suitable alloy materials, or any combination of the above materials.

[0025] As shown in operation 120, a portion of the alloy substrate 220 is removed along the first direction 201 to form a first trench 230 on the upper surface of the alloy substrate 220, dividing the alloy substrate 220 into a plurality of electrode regions 221 and a plurality of resistor regions 223, wherein each resistor region 223 is located between two adjacent electrode regions 221, and each first trench 230 is located above the corresponding resistor region 223. Methods for removing the alloy substrate 220 include, but are not limited to, dicing, scraping, other suitable methods for removing material, or combinations thereof. The number and shape of the first trenches 230 on the alloy substrate 220 can be adjusted according to actual needs such as the area of ​​the alloy substrate 220, the dicing width, or the specifications (e.g., resistance value) of the current sensing resistor. In some embodiments, the width of the first trench 230 is 0.15 mm to 0.40 mm. In some embodiments, the aspect ratio of the first trench 230 is 0.1 to 1.0. When the aspect ratio of the first trench 230 is within the aforementioned range, a relatively large or square opening facilitates subsequent processing of the bottom of the first trench 230. In some embodiments, the depth of the first trench 230 is less than half the thickness of the alloy substrate 220. When the depth of the first trench 230 is within the aforementioned conditions, the resistive region 223 has at least half the thickness of the alloy substrate 22, which helps to provide appropriate mechanical strength and control the resistance value of the resistive element produced later within a certain range (e.g., less than 10 mol / L).

[0026] As shown in operation 130, a portion of the alloy substrate 220 is removed along the second direction 203 to form a plurality of second trenches 240 on the upper surface of the alloy substrate 220, and these second trenches 240 expose the insulating layer 210. The method of removing the alloy substrate 220 in operation 130 may be the same as or different from the removal method in operation 120. The number and shape of the second trenches 240 on the alloy substrate 220 may be adjusted according to actual needs such as the area of ​​the alloy substrate 220, the cutting width, or the specifications (e.g., size) of the current sensing resistor. In some embodiments, since the insulating layer 210 and the alloy substrate 220 are composed of different materials with different mechanical properties (e.g., hardness), the second trenches 240 expose the top surface of the insulating layer 210 to ensure good surface flatness at the junction of the alloy substrate 220 and the insulating layer 210 and to maintain the desired surface morphology. In some embodiments, operation 130 removes a portion of the alloy substrate 220 and a portion of the insulating layer 210 along the second direction 203 to reduce the thickness of the insulating layer 210, thereby facilitating easier separation of the fabricated resistive element during operation 150 described later. The second direction 203 may not be parallel to the first direction 201, wherein, depending on the specifications of the current sensing resistor to be fabricated, the angle between the second direction 203 and the first direction 201 is greater than 0 degrees and less than 180 degrees, and preferably 90 degrees.

[0027] As shown in operations 140 and 150, another portion of the alloy substrate 220 is removed again along the first direction 201 to form a plurality of third trenches 250 on the upper surface of the alloy substrate 220, and these third trenches 250 expose the insulating layer 210 and distinguish the alloy substrate 220 into a plurality of independent resistive elements 260 (e.g., ...). Figure 3A As shown in the diagram, each resistive element 260 includes two electrode regions 221 and a resistive region 223, and each second trench 240 or each third trench 250 is located between each adjacent resistive element 260. In other words, each resistive element 260 is independently arranged on the insulating layer in an array. The method of removing the alloy substrate 220 in operation 140 may be the same as or different from the removal method in operation 120. The number and shape of the third trenches 250 on the alloy substrate 220 may be adjusted according to actual needs such as the area of ​​the alloy substrate 220, the cut width, or the specifications (e.g., size) of the current sensing resistor. Similar to operation 130, in some embodiments, the third trenches 250 expose the top surface of the insulating layer 210, or the bottom surface of the third trench is lower than the top surface of the insulating layer 210. It is understood that although the drawings of the present invention (e.g., Figure 2C and Figure 2D and the following Figure 3A and Figure 3BThe second trench 240 and the third trench 250 shown in the illustration expose the top surface of the insulating layer 210, but the invention is not limited thereto. In other examples, the bottom surface of the second trench 240 and / or the third trench 250 may be lower than the top surface of the insulating layer 210.

[0028] Please refer to the following at the same time Figure 1 and Figure 3A ,in Figure 3A To draw along Figure 2D A cross-sectional view of a current-sensing resistor cut along line segment A-A'. After operation 150 (i.e., forming the resistive element 260), the manufacturing method 100 of the present invention further includes filling a protective material into the first trench 230 of the resistive element 260 to form a protective layer 231 on the resistive region 223, wherein the protective layer 231 completely covers the resistive region 223, and the protective material includes, but is not limited to, solder resist ink (such as epoxy resin) and / or other suitable protective materials. The thickness of the protective layer 231 can be adjusted according to actual needs such as the size of the product. It should be noted that the top surface of the protective layer 231 is not higher than the top surface of the electrode region 221. In other embodiments, the top surface of the protective layer 231 may be higher than the top surface of the electrode region 221, but the protective layer 231 does not completely cover the top surface of the electrode region 221 to ensure that the electrode region 221 can serve as the electrode of the current-sensing resistor.

[0029] Please refer to the following at the same time Figure 1 and Figure 3B , Figure 3B A cross-sectional schematic diagram of a current-sensing resistor according to some embodiments of the present invention is provided. In some embodiments, after operation 140, the manufacturing method 100 of the present invention further includes processing the resistive region 223 to remove a portion of the resistive region 223, thereby adjusting the resistance value of the manufactured current-sensing resistor. The method of removing a portion of the resistive region 223 may include, but is not limited to, cutting, drilling, and / or other suitable methods for removing material. Depending on the desired resistance value of the current-sensing resistor, the removed resistive region 223 is... Figure 3B The shape can be quadrilateral, arc-shaped, or other suitable. In some embodiments, each resistive element 260 on the insulating layer 210 can be processed independently, so the cut shape of the removed resistive region 223 in each resistive element 260 can have the same or different shapes. In some embodiments, after the processing operation, the manufacturing method 100 of the present invention can selectively fill a protective material in... Figure 3B A protective layer 231 is formed on the medium resistance region 223. Figure 3B The method and materials used to form the protective layer 231 are the same as those used in the process. Figure 3A The protective layer 231 is used in the middle, so it will not be described in detail here.

[0030] Please continue to refer to Figure 3AIn some embodiments, after forming the protective layer 231, the manufacturing method 100 of the present invention further includes separating each resistive element 260 to obtain a resistive body for a current-sensing resistor. Separation methods include, but are not limited to, punching, cutting, and / or other suitable separation methods. After separating each resistive element 260, the manufacturing method of the present invention further includes forming an alloy layer on each resistive element 260 to form the desired current-sensing resistor, wherein this alloy layer is formed by electroplating, covering the electrode region of the resistive element 260 with a metal material, and the metal material includes copper, nickel, tin, other suitable metal materials, or combinations of the above metal materials.

[0031] In some specific examples, by using the aforementioned method, for an alloy substrate 220 with a thickness of 0.075 mm to 0.30 mm, by forming a first trench 230 with a width of 0.15 mm to 0.40 mm (aspect ratio of 0.1 to 0.35), a small-sized (e.g., long side less than 1.8 mm) current sensing resistor with a resistance temperature coefficient of less than 50 ppm / ℃ can be effectively produced, wherein the resistance value of each current sensing resistor is less than 10 mohm. In some specific examples, by using the aforementioned method, for an alloy substrate 220 with a thickness of 0.10 mm to 0.20 mm, by forming a first trench 230 with a width of 0.15 mm to 0.30 mm (aspect ratio of 0.15 to 0.3), a small-sized (e.g., long side less than 1.2 mm) current sensing resistor with a resistance temperature coefficient of less than 50 ppm / ℃ can be effectively produced, wherein the resistance value of each current sensing resistor is less than 5 mohm. In some specific examples, by means of the aforementioned method, for an alloy substrate 220 with a thickness of 0.1 mm to 0.15 mm, by forming a first trench 230 with a width of 0.15 mm to 0.25 mm (with an aspect ratio of 0.15 to 0.29), a small-sized (e.g., long side less than 0.7 mm) current sensing resistor with a resistance temperature coefficient of less than 50 ppm / ℃ can be effectively produced, wherein the resistance value of each current sensing resistor is less than 3 mohm.

[0032] In some applications, the aforementioned method can effectively produce current sensing resistors with small dimensions (e.g., a long side less than 1.8 mm) and a resistance temperature coefficient of less than 50 ppm / ℃. Furthermore, the fabrication method of this invention allows for the rapid fabrication of current sensing resistors through a simple removal operation. Therefore, the fabrication method of this invention does not require the use of existing soldering or photolithography techniques, thus effectively avoiding defects such as poor soldering and electrode deformation in the produced current sensing resistors.

[0033] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Those skilled in the art to which this invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

[0034] [Symbol Explanation]

[0035] 100: Method

[0036] 110, 120, 130, 140, 150: Operation

[0037] 200: Composite materials

[0038] 201, 203: Direction

[0039] 210: Insulation layer

[0040] 220:Alloy base material

[0041] 221: Electrode region

[0042] 223: Resistance Region

[0043] 230, 240, 250: Trench

[0044] 231: Protective layer

[0045] 260: Resistor element

[0046] A-A': Line segment.

Claims

1. A method for manufacturing a current sensing resistor, characterized in that, The method includes: A composite material is provided, wherein the composite material comprises an insulating layer and an alloy substrate disposed on the insulating layer, and the alloy substrate has a temperature coefficient of resistance of less than 50 ppm / ℃; A portion of the alloy substrate of the composite material is removed along a first direction to form a plurality of first grooves on the upper surface of the alloy substrate; Another portion of the alloy substrate of the composite material is removed along the second direction to form a plurality of second trenches, wherein the second trenches expose the insulating layer, and the first direction is perpendicular to the second direction; as well as After the second trenches are formed, another portion of the alloy substrate is removed along the first direction to form a plurality of third trenches and a plurality of resistive elements, wherein the third trenches expose the insulating layer, and each of the third trenches is disposed between adjacent first trenches, and the resistive elements are arranged in an array on the insulating layer.

2. The method for manufacturing a current sensing resistor according to claim 1, characterized in that, The alloy substrate has a thickness of less than 0.5 mm.

3. The method for manufacturing a current sensing resistor according to claim 1, characterized in that, The alloy substrate contains either copper-manganese-tin or copper-manganese-nickel.

4. The method for manufacturing a current sensing resistor according to claim 1, characterized in that, After forming the resistive elements, the method further includes removing a portion of the bottom surface of each of the first trenches.

5. The method for manufacturing a current sensing resistor according to claim 1, characterized in that, The aspect ratio of each of these first trenches is between 0.1 and 0.

35.

6. The method for manufacturing a current sensing resistor according to claim 1, characterized in that, After the third trenches are formed, the method further includes filling each of the first trenches with a protective material to form a protective layer.

7. The method for manufacturing a current sensing resistor according to claim 6, characterized in that, After the protective layer is formed, the method further includes separating each of the resistive elements to obtain the current sensing resistors.

8. The method for manufacturing a current sensing resistor according to claim 7, characterized in that, The method also includes forming an alloy layer on each of the current sensing resistors.

9. A current sensing resistor, manufactured by means of the method according to any one of claims 1 to 8, characterized in that, The long side of the current sensing resistor is less than 1.8 mm and the current sensing resistor has a resistance temperature coefficient of less than 50 ppm / ℃.

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