Thin-film resistor and circuit board

Abstract

Provided are a thin-film resistor and a circuit board. The thin-film resistor comprises a substrate layer and a first resistor layer, wherein at least one side surface of the substrate layer has several protrusions; the first resistor layer is located on the side surface of the substrate layer that has the protrusions; the ratio of the surface area of the side surface of the substrate layer that has the protrusions to the projection area of the substrate layer is 1.3-10; and the first resistor layer is located on the side surface of the substrate layer that has the protrusions, and is configured in the same shape as the substrate layer. The above definitions improve the uniformity of the first resistor layer deposited on a surface of the substrate layer, thereby improving the sheet-resistance uniformity of the first resistor layer, facilitating the preparation of an embedded resistor having relatively high precision, and facilitating the performance of a circuit board and even an electronic element.

Description

Thin film resistor and circuit board

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on July 5, 2023, with application number 202310821003.0 and invention name “A Thin Film Resistor and Circuit Board”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the technical field of thin film resistors, and in particular to a thin film resistor and a circuit board. Background Art

[0004] The integrated development of electronic components has placed higher demands on their performance and miniaturization. The use of thin-film resistors as integrated passive components can significantly reduce the surface parasitic effects and volume of semiconductor devices at high frequencies. Their high precision helps increase packaging density and improve device reliability, and they are widely used in applications such as high-performance amplifiers, line drivers, consumer electronics, and power management. The thin-film resistor's resistance layer is stacked on the surface of a substrate, so the uniformity of the resistance of the layer is easily affected by the substrate. Poor uniformity of the resistance of the layer can seriously affect the performance stability of the electronic component.

[0005] Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present application is how to improve the uniformity of the square resistance of the resistance layer of the thin film resistor, thereby providing a thin film resistor and a circuit board.

[0007] The present application provides a thin film resistor, comprising a base layer and a first resistor layer, wherein at least one side surface of the base layer has a plurality of protrusions, the first resistor layer is located on the side surface of the base layer having the protrusions, the ratio of the surface area of ​​the side surface of the base layer having the protrusions to the projected area of ​​the base layer is 1.3-10, and the first resistor layer is arranged in the same shape as the base layer.

[0008] Optionally, the ratio of the surface area of ​​the convex side surface of the base layer to the projected area of ​​the base layer is 2-7.

[0009] Optionally, the projection area of ​​the base layer is 4066 μm 2 When the surface area of ​​the base layer having the convex side surface is 20000 μm 2 -29000μm 2 .

[0010] Optionally, at least some of the protrusions meet the following condition: the average cross-sectional area from the bottom of the protrusion to 1 / 2 of the height of the protrusion is greater than the average cross-sectional area from 1 / 2 of the height of the protrusion to the top of the protrusion.

[0011] Optionally, the average cross-sectional area from the bottom of the protrusion to 1 / 2 of the height of the protrusion is greater than the average cross-sectional area from 1 / 2 of the height of the protrusion to the top of the protrusion by at least 30%.

[0012] Optionally, at least part of the protrusions meet the following condition: the minimum width from the bottom of the protrusion to 1 / 2 of the height of the protrusion is not less than the maximum width from 1 / 2 of the height of the protrusion to the top of the protrusion.

[0013] Optionally, the minimum width from the bottom of the protrusion to 1 / 2 of the height of the protrusion is not less than the maximum width from 1 / 2 of the height of the protrusion to the top of the protrusion, accounting for at least 30%.

[0014] Optionally, the distribution of the protrusions on the surface of the base layer is as follows: the maximum height of the protrusion is H, 1μm≤H≤25μm, wherein the number of protrusions with 1μm≤H≤14μm accounts for 70% to 90%, and the number of protrusions with 14μm≤H≤25μm accounts for 10% to 30%.

[0015] Optionally, the distribution of the protrusions on the surface of the base layer is as follows: the distance between the central axes of adjacent protrusions is D, and the number of protrusions with 2 μm≤D≤11 μm accounts for greater than or equal to 70%.

[0016] Optionally, the thin film resistor further includes a film layer located on a surface of the first resistor layer away from the base layer.

[0017] Optionally, a conductive layer is provided on a side of the film layer away from the first resistance layer.

[0018] Optionally, the conductive layer is a single-layer conductive layer or a multi-layer conductive layer.

[0019] Optionally, a second resistance layer is provided between the film layer and the conductive layer.

[0020] The present application also provides a circuit board comprising the above-mentioned thin film resistor.

[0021] The technical solution of this application has the following advantages:

[0022] The thin film resistor and circuit board provided in the present application limit the ratio of the surface area of ​​the raised side surface of the base layer to the projected area of ​​the base layer, so that the resistor material can be uniformly deposited on the surface of the base layer, thereby improving the uniformity of the square resistance of the first resistor layer, which is conducive to the preparation of embedded resistors with higher precision and meets the high-performance application requirements of circuit boards and even electronic components. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] FIG1 is a schematic diagram of a longitudinal cross-sectional structure of a thin film resistor provided in an embodiment of the present application;

[0025] FIG2 is a SEM scan of the substrate in FIG1 ;

[0026] FIG3 is a schematic diagram of the stacking relationship of another thin film resistor provided in an embodiment of the present application;

[0027] FIG4 is a schematic diagram of the stacking relationship of another thin film resistor provided in an embodiment of the present application;

[0028] FIG5 is a schematic diagram of the stacking relationship of another thin film resistor provided in an embodiment of the present application;

[0029] Explanation of reference numerals: 1 - base layer; 11 - protrusion; 2 - first resistance layer; 3 - film layer; 4 - conductive layer; 5 - second resistance layer. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solution of this application in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0031] In the description of this application, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on this application.

[0032] Thin-film resistors typically include a base layer and a resistor layer, with the resistor layer located on the raised side of the base layer. To ensure that thin-film resistors meet the requirements of circuit board applications, the morphology of the resistor layer needs to be designed. The resistor layer is a very thin layer, and its surface morphology is significantly affected by the base layer. After extensive experimental research, the inventors discovered that the ratio of the surface area of ​​the raised side of the base layer to the projected area of ​​the base layer affects the square resistance stability of the resistor layer. This ratio needs to be controlled within a certain range to ensure that the thin-film resistor meets the requirements of circuit board applications.

[0033] Referring to Figure 1 , this embodiment provides a thin-film resistor comprising a base layer 1 and a first resistor layer 2. The base layer 1 has a plurality of protrusions on at least one surface. The first resistor layer 2 is located on the side of the base layer 1 having the protrusions. The ratio of the surface area of ​​the base layer 1 having the protrusions to the projected area of ​​the base layer 1 is 1.3-10. By limiting the ratio of the surface area of ​​the base layer having the protrusions to the projected area of ​​the base layer, the resistor material can be uniformly deposited on the surface of the base layer, thereby improving the uniformity of the sheet resistance of the first resistor layer. This facilitates the preparation of highly precise embedded resistors that meet the high-performance application requirements of circuit boards and even electronic components.

[0034] Exemplarily, the ratio of the surface area of ​​the side of the base layer 1 having the protrusions 11 to the projected area of ​​the base layer 1 can be 1.3, 2, 3, 4, 5, 6, 7, 10, or any value between any two of the foregoing numbers. Optionally, the ratio of the surface area of ​​the side of the base layer 1 having the protrusions 11 to the projected area of ​​the base layer 1 is 2-7, which can further optimize the sheet resistance uniformity of the resistor layer. Optionally, the ratio of the surface area of ​​the side of the base layer 1 having the protrusions 11 to the projected area is 4-6, further improving the sheet resistance uniformity of the thin film resistor.

[0035] As a specific example, when the projection area of ​​the base layer 1 is 4066 μm 2 When the surface area of ​​the base layer 1 having the protrusion 11 is 20000 μm 2 -29000μm 2 .

[0036] It should be understood that the projected area described in this embodiment refers to the area of ​​the orthographic projection of the substrate layer 1 onto a plane after the thin-film resistor is attached to the plane. In other words, the area covered by the thin-film resistor on the plane. Because the first resistor layer 2 is very thin, the surface area of ​​the substrate layer 1 having the protrusion 11 can be obtained by measuring the surface area of ​​the first resistor layer 2.

[0037] In this embodiment, referring to FIG2 , protrusions 11 are actually accumulations of multiple small crystal grains. The shapes of protrusions 11 include, but are not limited to, polygonal pyramids, inverted cones, cones, needles, dendrites, crowns, hooks, stalactites, hanging ice, spirals, sawtooth shapes, and ripples. In the cross-sectional scan of the thin film resistor, the maximum height of protrusions 11 is higher than the thinnest thickness of substrate layer 1. The horizontal distance between the tops of protrusions 11 (i.e., the maximum height of the protrusions) is greater than or equal to 1.5 μm.

[0038] In order to better achieve the technical effects of the present invention and further improve the uniformity of the square resistance, in one embodiment, on the basis that the ratio of the surface area of ​​the side surface of the base layer 1 with the protrusion to the projected area of ​​the base layer 1 meets the above requirements, at least part of the protrusion meets the following conditions: the average cross-sectional area from the bottom of the protrusion to 1 / 2 of the height of the protrusion is greater than the average cross-sectional area from 1 / 2 of the height of the protrusion to the top of the protrusion.

[0039] To further optimize the sheet resistance uniformity of the thin-film resistor, the number of protrusions meeting the above conditions must account for at least 30% of the total number of protrusions on one side of the substrate layer. As a specific example, the number of protrusions meeting the above conditions can account for at least 50% of the total number of protrusions on one side of the substrate layer. The greater the proportion of protrusions meeting the above conditions, the better the sheet resistance uniformity of the first resistor layer.

[0040] In order to better achieve the technical effect of the present application and further improve the uniformity of the square resistance, in one embodiment, on the basis that the ratio of the surface area of ​​the side surface of the base layer 1 with the protrusion to the projected area of ​​the base layer 1 meets the above requirements, at least part of the protrusion meets the following conditions: the minimum width from the bottom of the protrusion to 1 / 2 of the height of the protrusion is not less than the maximum width from 1 / 2 of the height of the protrusion to the top of the protrusion, and the maximum width of the cross section of each height of the protrusion is the width value at this height; at this time, the protrusion is overall "water drop-shaped", and the resistance material is more easily and evenly formed on the rough surface of the base layer, with better uniformity and continuity.

[0041] To further optimize the sheet resistance uniformity of the thin-film resistor, the number of protrusions meeting the above conditions must account for at least 30% of the total number of protrusions on one side of the substrate layer. As a specific example, the number of protrusions meeting the above conditions can account for at least 50% of the total number of protrusions on one side of the substrate layer. The greater the proportion of protrusions meeting the above conditions, the better the sheet resistance uniformity of the first resistor layer.

[0042] In this embodiment, the thickness of the base layer 1 is 2μm-100μm, and the thickness of the base layer 1 can be optionally 8μm-35μm. The thickness of the first resistor layer 2 is 5nm-3μm, and the thickness of the first resistor layer 2 can be optionally 10nm-200nm. Exemplarily, the thickness of the base layer 1 can be 2μm, 4μm, 6μm, 8μm, 10μm, 20μm, 30μm, 35μm, 50μm, 60μm, 80μm, 100μm, or any value between any two of the above values; the thickness of the first resistor layer 2 can be 5nm, 10nm, 25nm, 50nm, 75nm, 100nm, 125nm, 150nm, 175nm, 200nm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, or any value between any two of the above values.

[0043] In this embodiment, the maximum height of the protrusion is H, 1μm≤H≤25μm. Specifically, the distribution of the protrusions on the surface of the base layer is as follows: the number of protrusions with a range of 1μm≤H≤14μm accounts for 70% to 90%, the number of protrusions with a range of 14μm≤H≤25μm accounts for 10% to 30%, and the total of the above proportions is less than or equal to 100%; optionally, the number of protrusions with a range of 1μm≤H≤4μm accounts for 10% to 50%, the number of protrusions with a range of 4μm<H≤14μm accounts for 30% to 80%, and the number of protrusions with a range of 14μm≤H≤25μm accounts for 3% to 10%, and the total of the above proportions is less than or equal to 100%; the maximum height H of the protrusions satisfies the above distribution, and the resulting square resistance uniformity of the thin film resistor can better meet the application requirements in circuit boards.

[0044] In this embodiment, at least some of the protrusions meet the following conditions: the spacing D between the center axes of adjacent protrusions is 2μm≤D≤11μm. For example, the spacing D between the center axes of adjacent protrusions can be 2μm, 4μm, 6μm, 8μm, 10μ, 11μm, or any value between any two of the above values. Optionally, the number of protrusions with 2μm≤D≤11μm accounts for greater than or equal to 70% to obtain better square resistance uniformity.

[0045] This embodiment specifies the ratio of the surface area of ​​the side of the base layer with the protrusions to the projected area of ​​the base layer, as well as the protrusion morphology. It also specifies the maximum height of the protrusions and the horizontal spacing between adjacent protrusions. A resistor layer that meets these requirements exhibits good sheet resistance uniformity, meeting the application requirements of thin-film resistors in circuit boards.

[0046] It should be noted that the thickness of the base layer 1, the thickness of the first resistor layer 2, and the maximum width and other related parameters in this embodiment are obtained by preparing the thin film resistor sample into slices and then measuring them under a scanning electron microscope. The magnification of the scanning electron microscope is 2000 times to 70000 times. The spacing of the central axes of the protrusions refers to the horizontal distance between the central axes of two adjacent protrusions. The central axis of the protrusion is the centerline of a single protrusion or the axis passing through the highest point of a single protrusion. In the cross-sectional scanning atlas of the thin film resistor, the maximum height of the protrusion is higher than the thinnest thickness of the base layer. When the horizontal distance between the maximum heights of two adjacent small protrusions is close, the two adjacent small protrusions can be regarded as a single large protrusion. The basis for judging whether the horizontal distance between the maximum heights of two adjacent small protrusions is close is that the horizontal distance between the maximum heights of the two adjacent small protrusions is less than half the width at half the height of the small protrusion with the smaller lateral dimension among the two small protrusions.

[0047] In this embodiment, the base layer 1 is made of a conductive material or a dielectric material. The base layer 1 can be a single-layer structure or a laminated structure. Conductive materials include, but are not limited to, copper, aluminum, titanium, zinc, iron, nickel, chromium, cobalt, silver, and gold. Other conductive materials are also possible, and are not listed in detail here. Specifically, the base layer can be copper foil, aluminum foil, titanium foil, zinc foil, iron foil, nickel foil, chromium foil, cobalt foil, silver foil, or gold foil. It can also be an alloy foil containing at least two of copper, aluminum, titanium, zinc, iron, nickel, chromium, cobalt, silver, and gold. It can also be a composite foil composed of at least two of copper foil, aluminum foil, titanium foil, zinc foil, iron foil, nickel foil, chromium foil, cobalt foil, silver foil, and gold foil, or other conductive materials. Dielectric materials include, but are not limited to, PET, PP, PS, ABF film, BT resin, polyacrylic acid, polyurethane, polyimide, or other dielectric materials. In a base layer with a multilayer structure, the materials between different layers can be the same or different.

[0048] The first resistor layer 2 is a key functional layer of the thin film resistor, which is used to realize the resistance function of the embedded resistor. The first resistor layer can be made of different materials according to the needs of different functions, and thus have different resistance characteristics. Specifically, the material of the first resistor layer includes but is not limited to at least one element of Ni, Cr, Si, P, N, Ti, Pt, Ta, Mo, Sn, and O. Specifically, the material can be NiCrSi, NiCrAlSi, NiP, NiCr, AlN, TiN, Pt, Cr, Cr-SiO, Cr-Si, Ti-Si, Ti-W, TaN, Mo and Ni-Sn. The materials that can meet the requirements of the preparation of resistors are all within the scope of the requirements of this solution and are not listed in detail here. The first resistor layer 2 can be a single-layer structure or a multi-layer structure stacked together. In the first resistor layer 2 with a multi-layer structure, the materials between different layers can be the same or different.

[0049] In this embodiment, the first resistor layer is formed by at least one process selected from electroplating, chemical plating, physical vapor deposition, and chemical vapor deposition. The sheet resistance of the first resistor layer is 1Ω-2000Ω.

[0050] As shown in Figure 3, as an optional embodiment, the thin-film resistor further includes a film layer 3 located on the surface of the first resistor layer 2 facing away from the base layer 1. This film layer protects the first resistor layer 2 from damage by external forces. Furthermore, when the thin-film resistor is attached to a circuit board, the film layer adheres to the first resistor layer 2 and the circuit board, improving the structural stability of the electronic device. Furthermore, the film layer can be used to create a foil-clad laminate that can be directly incorporated into rigid or flexible PCBs.

[0051] Specifically, the thickness of the film layer is 0.5 μm-100 μm. Exemplarily, the thickness of the film layer can be 2 μm, 5 μm, 7 μm, 10 μm, 12 μm, 15 μm, 20 μm, 30 μm, 40 μm, 55 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm. The film layer material includes but is not limited to polystyrene-based thermoplastic resins, vinyl acetate-based thermoplastic resins, polyester-based thermoplastic resins, polyethylene-based thermoplastic resins, polyamide-based thermoplastic resins, rubber-based thermoplastic resins, acrylic-based thermoplastic resins, phenolic-based thermosetting resins, epoxy-based thermosetting resins, thermoplastic polyimide-based thermosetting resins, urethane-based thermosetting resins, melamine-based thermosetting resins, alkyd-based thermosetting resins, and ABF resins. Resin materials that can meet the requirements of bonding are all within the scope of this solution and are not listed in detail here. Exemplary film layers include modified epoxy resins, modified acrylic resins, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polyethylene naphthalate, polystyrene, polyvinyl chloride, polysulfone, polyphenylene sulfide, polyetheretherketone, polyphenylene oxide, polytetrafluoroethylene, liquid crystal polymers, polyoxaline, epoxy glass cloth, and BT resin. Other film layer materials that meet the performance requirements are within the scope of this solution and are not listed in detail here. The specific thickness and material of the film layer are selected and set by those skilled in the art based on actual needs.

[0052] Optionally, referring to FIG4 , in one embodiment, a film layer 3 is provided in the thin film resistor, and a conductive layer 4 is provided on the side of the film layer 3 away from the first resistor layer 2, thereby forming a foil-clad plate containing the first resistor layer. The foil-clad plate has a four-layer structure and can be directly applied to a hard board or a soft board. Specifically, the conductive layer can be a single-layer structure or a multi-layer structure. That is, the conductive layer can be a copper foil, aluminum foil, titanium foil, zinc foil, iron foil, nickel foil, chromium foil, cobalt foil, silver foil or gold foil, or an alloy foil containing at least two of copper, aluminum, titanium, zinc, iron, nickel, chromium, cobalt, silver and gold. It can also be a composite foil composed of at least two of copper foil, aluminum foil, titanium foil, zinc foil, iron foil, nickel foil, chromium foil, cobalt foil, silver foil and gold foil. It can also be other conductive materials, which will not be detailed here. The material of the conductive layer can be the same as or different from the material of the base layer, and those skilled in the art can set it according to actual needs.

[0053] Optionally, referring to FIG5 , in one embodiment, a second resistor layer 5 is provided between the film layer 3 and the conductive layer 4, thereby forming an asymmetric structure. The material of the second resistor layer 5 may be the same as or different from that used for the first resistor layer 2, and those skilled in the art may configure the material based on actual needs. This embodiment forms the second resistor layer using at least one of electroplating, chemical plating, physical vapor deposition, and chemical vapor deposition processes. It should be noted that the materials used to prepare the first and second resistor layers in this embodiment are conventional materials in the art, and both the first and second resistor layers are continuous layer structures. The structure and material composition of the first and second resistor layers differ from those of conventional anti-rust or anti-oxidation layers.

[0054] This embodiment further provides a circuit board including the thin film resistor. The circuit board has all the advantages of the thin film resistor, which will not be described in detail here.

[0055] Specific examples and comparative examples are now provided as examples to support the technical effects of the technical solutions of this application. The thin-film resistors in both the examples and comparative examples include a base layer and a first resistor layer, wherein one surface of the base layer has a plurality of protrusions, and the first resistor layer is laminated on the side of the base layer having the protrusions. The base layer is 18μm thick copper foil, and the first resistor layer is made of NiCr alloy, with a thickness of 20nm.

[0056] Example 1

[0057] In this embodiment, the ratio of the surface area of ​​the surface of one side of the base layer having the protrusion to the projected area of ​​the base layer is 1.3, the average cross-sectional area from the bottom of the protrusion to 1 / 2 of the height of the protrusion is greater than or equal to the average cross-sectional area from 1 / 2 of the height of the protrusion to the top of the protrusion accounts for 30%, the number of protrusions with 2μm≤D≤11μm accounts for 70%, the maximum height of the protrusion is H, the number of protrusions with 1μm≤H≤14μm accounts for 70%, and the number of protrusions with 14μm≤H≤25μm accounts for 30%.

[0058] Example 2

[0059] In this embodiment, the ratio of the surface area of ​​the surface of one side of the base layer having the protrusion to the projected area of ​​the base layer is 10, the average cross-sectional area from the bottom of the protrusion to 1 / 2 of the height of the protrusion is greater than or equal to the average cross-sectional area from 1 / 2 of the height of the protrusion to the top of the protrusion accounts for 30%, the number of protrusions with 2μm≤D≤11μm accounts for 70%, the maximum height of the protrusion is H, the number of protrusions with 1μm≤H≤14μm accounts for 70%, and the number of protrusions with 14μm≤H≤25μm accounts for 30%.

[0060] Example 3

[0061] In this embodiment, the ratio of the surface area of ​​the surface of one side of the base layer having the protrusion to the projected area of ​​the base layer is 5.2, the average cross-sectional area from the bottom of the protrusion to 1 / 2 of the height of the protrusion is greater than or equal to the average cross-sectional area from 1 / 2 of the height of the protrusion to the top of the protrusion accounts for 30%, the number of protrusions with 2μm≤D≤11μm accounts for 70%, the maximum height of the protrusion is H, the number of protrusions with 1μm≤H≤14μm accounts for 70%, and the number of protrusions with 14μm≤H≤25μm accounts for 30%.

[0062] Example 4

[0063] In this embodiment, the ratio of the surface area of ​​the surface of one side of the base layer having the protrusion to the projected area of ​​the base layer is 5.2, the average cross-sectional area from the bottom of the protrusion to 1 / 2 of the height of the protrusion is greater than or equal to the average cross-sectional area from 1 / 2 of the height of the protrusion to the top of the protrusion, the proportion of protrusions is 60%, the number of protrusions with 2μm≤D≤11μm accounts for 70%, the maximum height of the protrusion is H, the number of protrusions with 1μm≤H≤14μm accounts for 70%, and the number of protrusions with 14μm≤H≤25μm accounts for 30%.

[0064] Example 5

[0065] In this embodiment, the ratio of the surface area of ​​the surface of one side of the base layer with the protrusion to the projected area of ​​the base layer is 5.2, the minimum width from the bottom of the protrusion to 1 / 2 of the height of the protrusion is not less than the maximum width from 1 / 2 of the height of the protrusion to the top of the protrusion accounts for 30%, the number of protrusions with 2μm≤D≤11μm accounts for 70%, the maximum height of the protrusion is H, the number of protrusions with 1μm≤H≤14μm accounts for 70%, and the number of protrusions with 14μm≤H≤25μm accounts for 30%.

[0066] Example 6

[0067] In this embodiment, the ratio of the surface area of ​​the surface of one side of the base layer with the protrusion to the projected area of ​​the base layer is 5.2, the minimum width from the bottom of the protrusion to 1 / 2 of the height of the protrusion is not less than the maximum width from 1 / 2 of the height of the protrusion to the top of the protrusion accounts for 60%, the number of protrusions with 2μm≤D≤11μm accounts for 70%, the maximum height of the protrusion is H, the number of protrusions with 1μm≤H≤14μm accounts for 70%, and the number of protrusions with 14μm≤H≤25μm accounts for 30%.

[0068] Comparative Example 1

[0069] The thin film resistor provided in this comparative example is different from the thin film resistor provided in Example 2 only in that: in the thin film resistor provided in this comparative example, the ratio of the surface area of ​​the side surface of the base layer having the protrusion to the projected area of ​​the base layer is 13.

[0070] Comparative Example 2

[0071] The only difference between the thin film resistor provided in this comparative example and the thin film resistor provided in Example 2 is that in the thin film resistor provided in this comparative example, the average cross-sectional area from the bottom of the protrusion to 1 / 2 of the height of the protrusion is greater than or equal to the average cross-sectional area from 1 / 2 of the height of the protrusion to the top of the protrusion, accounting for 20%.

[0072] Comparative Example 3

[0073] The thin film resistor provided in this comparative example is different from the thin film resistor provided in Example 2 only in that: in the thin film resistor provided in this comparative example, the number of protrusions with a range of 2 μm ≤ D ≤ 11 μm accounts for 40%.

[0074] Comparative Example 4

[0075] The only difference between the thin film resistor provided in this comparative example and the thin film resistor provided in Example 2 is that in the thin film resistor provided in this comparative example, the maximum height of the protrusion is H, the number of protrusions with 1μm≤H≤14μm accounts for 48%, and the number of protrusions with 14μm≤H≤25μm accounts for 52%.

[0076] Comparative Example 5

[0077] The only difference between the thin film resistor provided in this comparative example and the thin film resistor provided in Example 2 is that in the thin film resistor provided in this comparative example, the proportion of protrusions whose minimum width from the bottom of the protrusion to 1 / 2 of the height of the protrusion is not less than the maximum width from 1 / 2 of the height of the protrusion to the top of the protrusion is 18%.

[0078] The sheet resistance uniformity test was performed on the thin film resistors provided in Examples 1-6 and Comparative Examples 1-5. In the sheet resistance uniformity test, the sheet resistance M at different positions of the thin film resistor was first tested. The sheet resistance test points were evenly distributed on the surface of the thin film resistor, and the number of sheet resistance test points was 20. Then, the average sheet resistance M at different positions of the thin film resistor was calculated. ave , and select the maximum square resistance M max and the minimum square resistance M min , then calculate the upper limit and lower limit of square resistance uniformity: Upper limit of square resistance uniformity = (M max -M ave ) / M ave ×100%; lower limit of square resistance uniformity = (M min -M ave ) / M ave ×100%; see Table 1 for test results:

[0079] Table 1

[0080] As can be seen from Table 1, the sheet resistance uniformity of the thin film resistor of this embodiment is more prominent and the performance is more stable.

[0081] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of this application.

Claims

1. A thin film resistor, characterized in that: The thin film resistor includes a base layer and a first resistor layer, at least one side surface of the base layer has a plurality of protrusions, the first resistor layer is located on the side surface of the base layer having the protrusions, and the ratio of the surface area of ​​the side surface of the base layer having the protrusions to the projected area of ​​the base layer is 1.3-10.

2. The thin film resistor according to claim 1, characterized in that: The ratio of the surface area of ​​the convex side surface of the base layer to the projected area of ​​the base layer is 2-7.

3. The thin film resistor according to claim 1, characterized in that: The projected area of ​​the substrate layer is 4066 μm 2 When the surface area of ​​the base layer having the protrusion is 20000 μm 2 -29000μm 2 .

4. The thin film resistor according to claim 1, characterized in that: At least some of the protrusions satisfy the following condition: an average cross-sectional area from the bottom of the protrusion to 1 / 2 of the height of the protrusion is greater than an average cross-sectional area from 1 / 2 of the height of the protrusion to the top of the protrusion.

5. The thin film resistor according to claim 4, characterized in that: The average cross-sectional area from the bottom of the protrusion to 1 / 2 of the height of the protrusion is greater than the average cross-sectional area from 1 / 2 of the height of the protrusion to the top of the protrusion by at least 30%.

6. The thin film resistor according to claim 1, characterized in that: At least some of the protrusions satisfy the following condition: the minimum width from the bottom of the protrusion to 1 / 2 of the height of the protrusion is not less than the maximum width from 1 / 2 of the height of the protrusion to the top of the protrusion.

7. The thin film resistor according to claim 6, characterized in that: The proportion of protrusions for which the minimum width from the bottom of the protrusion to 1 / 2 of the height of the protrusion is not less than the maximum width from 1 / 2 of the height of the protrusion to the top of the protrusion is at least 30%.

8. The thin film resistor according to claim 1, characterized in that: The distribution of the protrusions on the surface of the base layer is as follows: the maximum height of the protrusion is H, 1μm≤H≤25μm, wherein the number of protrusions with 1μm≤H≤14μm accounts for 70% to 90%, and the number of protrusions with 14μm≤H≤25μm accounts for 10% to 30%.

9. The thin film resistor according to claim 1, characterized in that: The distribution of the protrusions on the surface of the base layer is as follows: the distance between the central axes of adjacent protrusions is D, and the number of protrusions with 2 μm≤D≤11 μm accounts for greater than or equal to 70%.

10. The thin film resistor according to any one of claims 1 to 9, characterized in that: The thin film resistor further includes a film layer located on a surface of the first resistor layer on a side away from the base layer.

11. The thin film resistor according to claim 10, characterized in that: A conductive layer is disposed on a side of the film layer away from the first resistance layer.

12. The thin film resistor according to claim 11, characterized in that: The conductive layer is a single conductive layer or a multi-layer conductive layer.

13. The thin film resistor according to claim 11, characterized in that: A second resistance layer is arranged between the film layer and the conductive layer.

14. A circuit board, characterized in that: A thin film resistor comprising any one of claims 1-13.

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