Film-shaped member and functional member

Abstract

Provided are: a film-shaped member suitable for light absorption or photothermal conversion applications, the film-shaped member comprising a film-shaped first part which includes nickel and phosphorus, and a second part which is located on one main-surface side of the first part and includes nickel, oxygen, and phosphorus; and a functional member including this film-shaped member. In this film-shaped member, the phosphorus content in the second part is not lower than the phosphorus content in the first part. When the second-part-side main surface is examined with a scanning electron microscope from the normal direction of the film-shaped member to obtain an image of secondary electrons and a luminance distribution of the image of secondary electrons is binarized by Otsu's method to determine a threshold value, then in the luminance distribution, a first region on the higher luminance side of the threshold value and a second region on the lower luminance side of the threshold value each have a peak. The ratio Rp of the phosphorus content in the second part to the phosphorus content in the first part satisfies Rp≥1 and the average sharpness Ps satisfies Ps≥1.3.

Description

Membrane-like members and functional members

[0001] The present invention relates to a film-like member having a predetermined surface shape, and a functional component having the film-like member.

[0002] Patent Document 1 discloses a light absorbing layer having a plurality of recesses on one main surface, at least a portion of the inner surfaces of the plurality of recesses being made of a nickel oxide compound, and characterized in that when near-infrared light of 2 μm is irradiated onto the one main surface, the total reflectance, which is the sum of the specular reflectance and the diffuse reflectance, is 2% or less. In addition, the boundaries of the plurality of recesses are continuous in a ridge-like manner, and each recess is formed in the shape of a crater surrounded by the ridge-like boundary.

[0003] Japanese Patent Application Laid-Open No. 2023-086192

[0004] The light-absorbing layer disclosed in Patent Document 1 is an effective component with a low total reflectance, but there is still room for improvement when considering its use as a photothermal conversion component. The present invention aims to provide a film-like component suitable for applications such as absorbing light to reduce reflection and converting light to heat, and a functional component having this film-like component.

[0005] In one aspect, the present invention provides a film-like member comprising a film-like first portion containing nickel and phosphorus, and a second portion located on one main surface side of the first portion and containing nickel, oxygen, and phosphorus, wherein the phosphorus content in the second portion is equal to or greater than the phosphorus content in the first portion, and a secondary electron image is obtained by observing the main surface of the film-like member on the side of the second portion in a normal direction of the film-like member with a scanning electron microscope, and a threshold is determined by performing a binarization process using Otsu's method on the brightness distribution of the secondary electron image. The present invention provides a film-like member in which a first region on the high-brightness side from the threshold value and a second region on the low-brightness side from the threshold value both have peaks, and when a binary image is obtained by binarizing the secondary electron image using the threshold value and a first length L1 which is the average value of the circular equivalent diameters Φ1 of the first region in the binary image and a second length L2 which is the average value of the circular equivalent diameters Φ2 of the Voronoi regions in a Voronoi diagram obtained by performing Voronoi division on the binary image using the center of gravity of the first region as a generating point are calculated, the film-like member has an average sharpness Ps defined as L2 / L1 of 1.3 or more.

[0006] As described above, when the brightness distribution of a secondary electron image obtained by observing the principal surface of the second portion side of the film-like member in the normal direction has peaks in both the first and second regions set on either side of a threshold value, the surface shape of the principal surface of the second portion side of the film-like member is a basic structure in which multiple protrusions protruding independently of each other are arranged in the in-plane direction, with bases positioned to surround each of the protrusions. In this specification, this surface shape is referred to as a "protrusion-independent surface shape." In contrast, a surface shape having multiple recesses extending from the tops of continuous protrusions, each of which is independent of each other and has a basic structure resembling a terrain of numerous scattered craters surrounded by ridges, is referred to as a "depression-independent surface shape." The brightness distribution of a secondary electron image obtained by observing a depression-independent surface shape does not have a peak in the first region on the high brightness side, unlike a projection-independent surface shape.

[0007] The inventors have confirmed that the surface shape of the light-absorbing layer disclosed in Patent Document 1 sometimes has independent recesses, the depth of which is equal to the thickness of the light-absorbing layer ( Figures 8A and 8B ). Light-absorbing layers with such deep recesses run the risk of having through-holes that penetrate the thickness of the light-absorbing layer to the substrate. These through-holes result in light transmission through a portion of the light-absorbing layer. Light transmission through the through-holes reduces the light absorption rate and photothermal conversion rate of the light-absorbing layer. To avoid these problems, it is practically necessary to increase the thickness of the underlayer (light-colored region 20X in Figure 9B ) in the light-absorbing layer. Furthermore, when the light-absorbing layer is used as a photothermal conversion element, a large thickness of the underlayer (light-colored region 20X) can increase the heat capacity of the underlayer (light-colored region 20X), potentially resulting in secondary problems such as reduced heat transfer response and temperature rise / fall response. Furthermore, a large thickness of the light-absorbing layer, including the underlayer (light-colored region 20X), can be detrimental to miniaturizing and thinning the film-like element.

[0008] In contrast, when the film-like member according to the present invention has a surface shape with independent convex portions, the possibility of through-holes being formed, which is a concern when the film-like member has a surface shape with large, deep concave portions in the independent concave portion type, is particularly low. Therefore, there is no need to increase the overall thickness of the film-like member, making it easy to use as a low-reflection member or a photothermal conversion member.

[0009] Furthermore, by satisfying that the phosphorus content in the second portion is equal to or greater than the phosphorus content in the first portion and that the average sharpness Ps is 1.3 or greater, the film-like member can stably exhibit its light absorption function and photothermal conversion function appropriately. Specifically, when light in the wavelength range of 0.8 μm to 2.0 μm (hereinafter also referred to as "NIR: near infrared") is irradiated onto the main surface of the film-like member on the second portion side, the average value Rt of the total reflectance (average NIR total reflectance) can easily be 2% or less.

[0010] It may be preferable that the phosphorus content of the second portion of the film member be 4.5 mass % or more and 7 mass % or less.

[0011] In the above-described film-like member, it is preferable that the first portion is a nickel-phosphorus alloy, the second portion is an oxide of the nickel-phosphorus alloy continuous with the first portion, and the phosphorus content ratio of the second portion to the first portion (phosphorus content ratio Rp) is 1.0 or more. Because both the first and second portions contain nickel-phosphorus, they have good adhesion and are less likely to peel off from the first portion due to differences in thermal expansion coefficients or external forces. Furthermore, it is not necessary to increase the thickness of the film-like member, particularly the thickness of the first portion, to prepare for excessively deep recesses. Even if the film-like member or the second portion is thin, a good oxide composition and shape can be obtained, providing efficient light absorption and photothermal conversion functions.

[0012] In the above-described film-like member, the coefficient of variation of the individual sharpness Pi, calculated by Φ2 / Φ1, which is the equivalent circle diameter Φ1 and the equivalent circle diameter Φ2, may be 0.4 or less. When the coefficient of variation, defined as standard deviation / average value, is small, the variation in the individual sharpness Pi is relatively small, and the possibility of having an excessively deep recess is low. Therefore, it is not necessary to increase the thickness of the film-like member, particularly the thickness of the first portion, in preparation for an excessively deep recess, and an increase in the heat capacity of the film-like member can be suppressed.

[0013] In the above-described film-like member, the first portion may include a nickel-phosphorus plating. In this case, it is sometimes preferable that the second portion include a nickel-phosphorus plating modified portion continuous with the first portion. When the second portion includes a nickel-phosphorus plating modified portion continuous with the first portion, peeling between the first portion and the second portion is unlikely to occur, and deterioration of the light absorption function and the light-to-heat conversion function is suppressed. Furthermore, even if the first portion and the second portion have different thermal expansion coefficients, because the first portion and the second portion have a continuous structure, peeling between the first portion and the second portion due to the difference in thermal expansion coefficients is unlikely to occur.

[0014] When the first portion includes nickel phosphorus plating, the modified portion is preferably an oxide of the nickel phosphorus plating, and the phosphorus content ratio of the second portion to the first portion is preferably 1.0 or more. Furthermore, when the phosphorus content ratio of the second portion to the first portion is 1.0 or more, it is not necessary to increase the thickness of the film-like member, particularly the thickness of the first portion, in preparation for an excessively deep recess, and a good oxide composition and shape can be obtained even if the film-like member is thin, thereby efficiently providing light absorption function and light-to-heat conversion function.

[0015] In the above-mentioned film-like member, the average thickness of the first portion may be 6 μm or less, and the average thickness of the second portion may be 2 μm or less. From the viewpoint of suppressing an increase in the heat capacity of the film-like member, it is preferable that the thickness of the film-like member is small.

[0016] In another aspect, the present invention provides a functional component comprising a substrate and the above-described film member provided on the substrate, the functional component having an average total reflectance Rt of 2% or less when irradiated with light in the wavelength range of 0.8 μm to 2.0 μm on the film member side. Such a functional component can be used as a light absorbing component or a light-to-heat converting component.

[0017] According to the present invention, a film-like member having a light absorbing function equivalent to that of the light absorbing members according to the prior art, which is thin and has a small heat capacity, is provided. Therefore, the film-like member according to the present invention or a functional member including the same can be suitably used not only as a light absorbing member but also as a light-to-heat converting member.

[0018] 2C is an explanatory diagram of a functional member according to an embodiment of the present invention; FIG. 2D is a diagram showing a secondary electron image (surface observation image 1) obtained by observing the main surface of the second portion side of the functional member according to Example 1 (example of the present invention) with a scanning electron microscope in the normal direction to the main surface; FIG. 2E is a diagram showing a secondary electron image (cross-section observation image 1) obtained by observing the cross section of the functional member according to Example 1 (example of the present invention) with a scanning electron microscope; FIG. 2F is a diagram in which symbols indicating shape features are added to FIG. 2C; FIG. 2G is a diagram showing a secondary electron image (surface observation image 2) obtained by observing the main surface of the second portion side of the functional member according to Example 2 (example of the present invention) with a scanning electron microscope in the normal direction to the main surface; FIG. 2G is a diagram showing a secondary electron image (cross-section observation image 2) obtained by observing the main surface of the second portion side of the functional member according to Example 2 (example of the present invention) with a scanning electron microscope in the normal direction to the main surface; FIG. 2F is a diagram showing a secondary electron image (cross-section observation image 2) obtained by observing the cross section of the functional member according to Example 2 (example of the present invention) with a scanning electron microscope; 1 is a diagram showing a secondary electron image (surface observation image 3) obtained by observing the main surface of the second portion side of the functional member according to Example 3 (example of the present invention) with a scanning electron microscope in the normal direction to the main surface. FIG. 2 is a diagram showing a secondary electron image (cross-section observation image 3) obtained by observing the main surface of the second portion side of the functional member according to Example 3 (example of the present invention) with a scanning electron microscope in a direction tilted from the normal direction to the main surface. FIG. 3 is a diagram showing a secondary electron image (surface observation image 4) obtained by observing the main surface of the second portion side of the functional member according to Example 4 (example of the present invention) with a scanning electron microscope in the normal direction to the main surface. FIG. 4 is a diagram showing a secondary electron image (cross-section observation image 4) obtained by observing the main surface of the second portion side of the functional member according to Example 4 (example of the present invention) with a scanning electron microscope in a direction tilted from the normal direction to the main surface. FIG. 5 is a diagram showing a secondary electron image (cross-section observation image 4) obtained by observing the cross-section of the functional member according to Example 4 (example of the present invention) with a scanning electron microscope. FIG. 10 is a diagram showing a secondary electron image (surface observation image 5) obtained by observing the main surface of the second portion side of the functional component of Example 5 (comparison example) with a scanning electron microscope in the normal direction to the main surface.1 is a diagram showing a secondary electron image obtained by observing the main surface of the second portion side of the functional member according to Example 5 (Comparative Example) with a scanning electron microscope in a direction tilted from the normal direction of the main surface. FIG. 2 is a diagram showing a secondary electron image (cross-section image 5) obtained by observing the cross section of the functional member according to Example 5 (Comparative Example) with a scanning electron microscope. FIG. 3 is a diagram showing a secondary electron image (surface image 6) obtained by observing the main surface of the second portion side of the functional member according to Example 6 (Comparative Example) with a scanning electron microscope in a direction tilted from the normal direction of the main surface. FIG. 4 is a diagram showing a secondary electron image (cross-section image 6) obtained by observing the cross section of the functional member according to Example 6 (Comparative Example) with a scanning electron microscope. FIG. 5 is a surface observation view (surface observation image 7) of the light absorbing layer of the member according to Reference Example 1 (Example 1 of Patent Document 1). FIG. 6 is a cross-section observation view (cross-section image 7) of the light absorbing layer of the member according to Reference Example 1 (Example 1 of Patent Document 1). 1 is a surface observation diagram (surface observation image 8) of the light absorbing layer of a member according to Reference Example 2 (Example 2 of Patent Document 1). FIG. 2 is a cross-sectional observation diagram (cross-sectional observation image 8) of the light absorbing layer of a member according to Reference Example 2 (Example 2 of Patent Document 1). FIG. 3 is a graph showing the relationship between the phosphorus content ratio Rp and the average NIR total reflectance Rt. FIG. 4 is a diagram showing the luminance distribution of surface observation image 1 and the results of performing binarization processing by Otsu's method on this luminance distribution. FIG. 5 is a diagram showing a binary image (binary image 1) obtained by performing binarization processing by Otsu's method on surface observation image 1. FIG. 6 is a diagram showing the luminance distribution of surface observation image 2 and the results of performing binarization processing by Otsu's method on this luminance distribution. FIG. 7 is a diagram showing a binary image (binary image 2) obtained by performing binarization processing by Otsu's method on surface observation image 2. FIG. 8 is a diagram showing the luminance distribution of surface observation image 3 and the results of performing binarization processing by Otsu's method on this luminance distribution. FIG. 9 is a diagram showing a binary image (binary image 3) obtained by performing binarization processing by Otsu's method on surface observation image 3. 1 is a diagram showing the luminance distribution of a surface observation image 4 and the result of performing binarization processing by Otsu's method on this luminance distribution; FIG. 2 is a diagram showing a binary image (binary image 4) obtained by performing binarization processing by Otsu's method on the surface observation image 4; FIG. 3 is a diagram showing the luminance distribution of a surface observation image 5 and the result of performing binarization processing by Otsu's method on this luminance distribution; and FIG. 4 is a diagram showing a binary image (binary image 5) obtained by performing binarization processing by Otsu's method on the surface observation image 5.1 shows the luminance distribution of a surface observation image 6 and the results of performing binarization processing using Otsu's method on this luminance distribution. It also shows a binary image (binary image 6) obtained by performing binarization processing using Otsu's method on the surface observation image 6. It also shows the luminance distribution of a surface observation image 7 and the results of performing binarization processing using Otsu's method on this luminance distribution. It also shows a binary image (binary image 7) obtained by performing binarization processing using Otsu's method on the surface observation image 7. It also shows the luminance distribution of a surface observation image 8 and the results of performing binarization processing using Otsu's method on this luminance distribution. It also shows a binary image (binary image 8) obtained by performing binarization processing using Otsu's method on the surface observation image 8. It also shows a Voronoi diagram (Voronoi diagram 1) obtained by performing Voronoi tessellation using the center of gravity of the first region of binary image 1 as the generating point. It also shows a composite diagram (composite diagram 1) in which binary image 1 and Voronoi diagram 1 are superimposed. It also shows a Voronoi diagram (Voronoi diagram 2) obtained by performing Voronoi tessellation using the center of gravity of the first region of binary image 2 as the generating point.

[0033] This is a diagram (composite diagram 2) in which binary image 2 is superimposed on Voronoi diagram 2. This is a Voronoi diagram (Voronoi diagram 3) obtained by performing Voronoi tessellation using the center of gravity of the first region of binary image 3 as the generating point (Voronoi diagram 3). This is a diagram (composite diagram 3) in which binary image 3 is superimposed on Voronoi diagram 3. This is a Voronoi diagram (Voronoi diagram 4) obtained by performing Voronoi tessellation using the center of gravity of the first region of binary image 4 as the generating point (Voronoi diagram 4). This is a diagram (composite diagram 4) in which binary image 4 is superimposed on Voronoi diagram 4. This is a Voronoi diagram (Voronoi diagram 5) obtained by performing Voronoi tessellation using the center of gravity of the first region of binary image 5 as the generating point (Voronoi diagram 5). This is a diagram (composite diagram 5) in which binary image 5 is superimposed on Voronoi diagram 5. This is a Voronoi diagram (Voronoi diagram 6) obtained by performing Voronoi tessellation using the center of gravity of the first region of binary image 6 as the generating point (Voronoi diagram 6). This is a diagram (composite diagram 6) in which binary image 6 is superimposed on Voronoi diagram 6. 1 is a diagram showing the relationship between the boundary B1 between the first region and the second region and the boundary B2 of the Voronoi region. FIG. 2 is an explanatory diagram of the equivalent circle diameter Φ1 and the equivalent circle diameter Φ2. FIG. 3 is a graph showing the relationship between the average sharpness Ps and the average NIR total reflectance Rt. FIG. 4 is a graph showing the relationship between the phosphorus content ratio Rp and the average sharpness Ps. FIG. 5 is a normalized frequency distribution of the individual sharpness Pi of each example.

[0019] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each drawing, the same components are designated by the same reference numerals, and their description will be omitted. Reference coordinates are indicated in each drawing as appropriate to indicate the positional relationship of each component.

[0020] Fig. 1 is an explanatory diagram of a functional component according to one embodiment of the present invention. As shown in Fig. 1, the functional component 100 according to this embodiment includes a substrate 40 and a film-like component 10 provided on the substrate 40. In Fig. 1, the substrate 40 is a plate-like component with its thickness direction in the Z direction, and the film-like component 10 is provided on one side (Z1 side) of the main surface of the substrate 40. The film-like component 10 includes a film-like first portion 20 proximal to the substrate 40 and a second portion 30 located on one side of the first portion 20 (the Z1 side in Fig. 1).

[0021] The surface shape of the second portion 30 side (Z1 side) of the film-like member 10 is an independent convex type. In an independent convex type surface shape, the basic structure is a structure in which multiple convex portions protruding independently of one another are aligned in the in-plane direction, with the bases positioned to surround each convex portion. Therefore, light irradiated onto the surface of the second portion 30 side (Z1 side) of the film-like member 10 penetrates the gaps between adjacent convex portions and is absorbed by the sides and bottoms of the convex portions, making it difficult for the light to return to the irradiated light side (Z1 side). Therefore, the film-like member 10 has excellent light absorption function. Specifically, when light in the wavelength range of 0.8 μm to 2.0 μm (hereinafter also referred to as "NIR: near-infrared") is irradiated onto the main surface of the second portion 30 side (Z1 side) of the film-like member 10, the total reflectance (average NIR total reflectance Rt) is easily 2% or less. Because the film member 10 has such a light absorption function, in one embodiment, the functional component 100 including the film member 10 has an average NIR total reflectance Rt of 2% or less on the film member 10 side. The average NIR total reflectance Rt of the film member 10 according to this embodiment may be preferably 1% or less, more preferably 0.7% or less, and particularly preferably 0.5% or less.

[0022] Furthermore, because the surface of the film-like member 10 on the second portion 30 side (Z1 side) has an independent convex shape, there is a low possibility of through holes occurring in the film-like member 10 in the stacking direction (Z direction) of the first portion 20 and the second portion 30. Therefore, there is no need to make the thickness of the first portion 20 excessively large, and it is possible to keep the heat capacity of the film-like member 10 low. Therefore, the film-like member 10 can have excellent heat transfer response and temperature rise / fall response after photothermal conversion, and a functional member 100 including the film-like member 10 can be used as a light absorption member or photothermal conversion member in small devices such as optical waveguides and MEMS.

[0023] The first portion 20 may include nickel-phosphorus plating. When the film-like member 10 is manufactured by chemically altering (modifying) the nickel-phosphorus plating, the phosphorus concentration of the nickel-phosphorus plating of the first portion 20 may affect the surface shape of the first portion 20 and the shape of the second portion 30. The average thickness of the first portion 20 may be 6 μm or less. The average thickness of the first portion 20 directly affects the heat capacity of the film-like member 10, and may therefore affect the heat transfer response and temperature rise / fall response of the film-like member 10 after photothermal conversion. In the film-like member 10 according to this embodiment, the average thickness of the first portion 20 may be 6 μm or less, allowing the film-like member 10 to have good heat transfer response and temperature rise / fall response after photothermal conversion.

[0024] The second portion 30 may contain nickel and phosphorus. In this case, it may be preferable that the phosphorus content be 4.5% by mass or more and 7% by mass or less. In a preferred example, the second portion 30 includes a nickel-phosphorus-plated modified portion continuous with the first portion 20. When the second portion 30 includes a nickel-phosphorus-plated modified portion continuous with the first portion 20, peeling between the first portion 20 and the second portion 30 is unlikely to occur, suppressing deterioration of the light absorption function and photothermal conversion function. Furthermore, even if the first portion 20 and the second portion 30 have different thermal expansion coefficients, because the first portion 20 and the second portion 30 have a continuous structure, peeling between the first portion 20 and the second portion 30 due to the difference in thermal expansion coefficients is unlikely to occur. The average thickness of the second portion 30 may be 2 μm or less. From the perspective of miniaturizing and thinning the film-like member 10, a small thickness of the film-like member 10 is preferable. For example, this is effective for application to small devices such as optical waveguides and MEMS.

[0025] (Examples) The detailed structure of the functional member 100 will be described below using specific examples. FIG. 2A is a diagram showing a secondary electron image (surface observation image 1) obtained by observing the main surface of the second portion side of the functional member according to Example 1 (example of the present invention) with a scanning electron microscope in the normal direction to the main surface. FIG. 2B is a diagram showing a secondary electron image (oblique observation image 1) obtained by observing the main surface of the second portion side of the functional member according to Example 1 (example of the present invention) with a scanning electron microscope in a direction tilted from the normal direction to the main surface. FIG. 2C is a diagram showing a secondary electron image (cross-section observation image 1) obtained by observing the cross section of the functional member according to Example 1 (example of the present invention) with a scanning electron microscope. FIGS. 3A to 3C are diagrams showing the results of observation of the functional member according to Example 2 (example of the present invention) in the same manner as the functional member according to Example 1. FIGS. 4A to 5C are the results of observation of the functional members according to Examples 3 and 4, which are examples of the present invention, and FIGS. 6A to 7C are the results of observation of the functional members according to Examples 5 and 6, which are comparative examples. 8A and 8B show secondary electron images (surface image 7) obtained by observing the main surface of the light absorbing layer of a member according to Example 1 of Patent Document 1 (referred to herein as "Reference Example 1") in the normal direction of the main surface with a scanning electron microscope, and a secondary electron image (cross-section image 7) obtained by observing a cross-section of the light absorbing layer with a scanning electron microscope. FIGS. 9A and 9B show secondary electron images (surface image 8) obtained by observing the main surface of the light absorbing layer of a member according to Example 2 of Patent Document 1 (referred to herein as "Reference Example 2") in the normal direction of the main surface with a scanning electron microscope, and a secondary electron image (cross-section image 8) obtained by observing a cross-section of the light absorbing layer with a scanning electron microscope. Table 1 shows the relationship between the examples and reference examples, the types of observation images, and the figure numbers. Table 1 also shows information about other images, etc., described below.

[0026]

[0027] The film-like members 10 (Examples 1 to 4) and 10C (Examples 5 and 6) according to the examples were manufactured as follows. First, a strike-plated layer 21 was formed on a stainless steel substrate 40 by nickel strike plating, and then a nickel-phosphorus electroless plating layer was formed on the strike-plated layer 21 using a nickel-phosphorus electroless plating solution having a different composition. The members thus obtained were then washed with hydrogen peroxide (1 mol / dm 3 about) and copper ions (0.1 mol / dm 3 The nickel-phosphorus electroless plating layer was modified by immersing the film-like member 10, 10C in an acidic mixed solution (liquid temperature: about 30°C) containing about 10% nickel (about 10%) for 4 to 5 minutes. This resulted in obtaining functional components 100, 100C including film-like members 10, 10C having a main portion 22 of a first portion 20 based on an unmodified nickel-phosphorus electroless plating layer and a second portion 30 produced by the modification. The electroless plating solution was diluted with pure water.

[0028] The average value of the total reflectance (average NIR total reflectance) Rt was measured when light (NIR: near infrared) in the wavelength range of 0.8 μm to 2.0 μm was irradiated on the main surface on the second portion 30 side of the film-like member 10 according to the present invention (Examples 1 to 4) and the film-like member 10C according to the comparative example (Examples 5 and 6), and on the main surface opposite to the side facing the substrate 40 in the light-absorbing layer 10X according to Reference Examples 1 and 2. The results are shown in Table 2.

[0029] As shown in Table 2, the average NIR total reflectance Rt of the film-like member 10 according to the present invention (Examples 1 to 4) was 2% or less. In contrast, the average NIR total reflectance Rt of the main surface on the second portion 30 side of the film-like member 10C according to the comparative example (Examples 5 and 6) exceeded 2%. The average NIR total reflectance Rt of Reference Examples 1 and 2 was 2% or less.

[0030] The film member 10 included in the functional component 100 according to Examples 1 to 4 of the present invention had the cross-sectional structures shown in Fig. 2C (cross-sectional image 1) to Fig. 5C (cross-sectional image 4), respectively. Specifically, the main portion 22 of the first portion 20 of the film member 10, located on a nickel strike-plated layer 21 provided in contact with the substrate 40 as part of the first portion 20, was composed of nickel-phosphorus electroless plating provided on the nickel strike-plated layer 21, and the second portion 30 was a modified portion formed by chemically modifying the nickel-phosphorus plating that constituted the main portion 22. Therefore, the second portion 30 was continuous with the first portion 20 (main portion 22).

[0031] The film member 10C of the functional component 100C according to Example 5 and Example 6, which are comparative examples, had the cross-sectional structures shown in Fig. 6C (cross-sectional image 5) and Fig. 7C (cross-sectional image 6), respectively, and their basic structure was common to that of the film member 10. Specifically, the film member 10C had a first portion 20 having a nickel strike plating layer 21 and a main portion 22, and a second portion 30C which was a modified portion of the main portion 22, and the second portion 30C was continuous with the first portion 20.

[0032] When cross-sectional observation images 1 to 6 were obtained, composition analysis of the first portion 20 and the second portion 30 was performed. The results are shown in Table 3 below. In Table 3, P1, O1, and Ni1 are the contents (unit: mass %) of phosphorus, oxygen, and nickel in the first portion 20, respectively, and P2, O2, and Ni2 are the contents (unit: mass %) of phosphorus, oxygen, and nickel in the second portion 30, respectively.

[0033]

[0034] As shown in Table 3, the phosphorus content P2 in the second portion 30 of the membrane member 10 according to Example 1 was equal to or greater than the phosphorus content P1 in the first portion 20. That is, in the membrane member 10 according to Example 1, the phosphorus content ratio Rp (=P2 / P1), which is the ratio of the phosphorus content P2 in the second portion 30 to the phosphorus content P1 in the first portion 20, was equal to or greater than 1. In the membrane members 10 according to Examples 2 to 4, similar to the membrane member 10 according to Example 1, the phosphorus content P2 in the second portion 30 was equal to or greater than the phosphorus content P1 in the first portion 20. Specifically, in Examples 1 to 4, the phosphorus content P1 in the first portion 20 was equal to or greater than 4.33 mass% and equal to or less than 5.20 mass%, while the phosphorus content P2 in the second portion 30 was equal to or greater than 5.45 mass% and equal to or less than 6.55 mass%.

[0035] When the phosphorus content ratio Rp is 1 or greater, the chemical reaction of the material constituting the main portion 22 in the first portion 20 proceeds appropriately, and the second portion 30 has a modified portion with a good shape. This results in a convex portion C having an appropriate length in the thickness direction (Z direction) of the film-like member 10, as shown in FIG. 2D , making it easier to obtain a film-like member 10 with good light absorption and photothermal conversion functions. Here, as described below, the convex portion C is composed of a protruding portion P of the first portion 20 and a second portion 30 protruding from the protruding portion P and including a sharp portion S. The length of the convex portion C in the thickness direction is the length in the Z direction from the bottom B of the first portion 20 to the sharp portion S of the second portion 30.

[0036] In contrast, in the film-like members 10 according to Examples 5 and 6, which are comparative examples, the phosphorus content P2 in the second portion 30 was less than the phosphorus content P1 in the first portion 20, i.e., the phosphorus content ratio Rp was less than 1. FIG. 10 is a graph showing the relationship between the phosphorus content ratio Rp and the average NIR total reflectance Rt, created based on the measurement results shown in Table 1. FIG. 10 confirms that when the phosphorus content ratio Rp is 1 or greater in the film-like member 10, it is easy to obtain a film-like member 10 with good characteristics. Specifically, it was confirmed that the total reflectance (average NIR total reflectance Rt) was 1% or less when light (NIR: near-infrared) in the wavelength range of 0.8 μm to 2.0 μm was irradiated onto the main surface of the film-like member on the second portion side.

[0037] Furthermore, as is clear from the composition measurement results shown in Table 3, the main portion 22 of the first portion 20 is a nickel-phosphorus-based alloy, and the modified portion of the second portion 30 contains an oxide of the nickel-phosphorus-based alloy. Because both the first portion 20 and the second portion 30 contain nickel-phosphorus, they have good adhesion and are less likely to peel off from each other due to differences in thermal expansion coefficients or external forces. Furthermore, there is no need to increase the thickness of the film-like member 10, particularly the thickness of the first portion 20, to prepare for excessively deep recesses. Even if the film-like member 10 is made thin, a good oxide composition and shape can be obtained, providing efficient light absorption and photothermal conversion functions.

[0038] A component 100X including a light-absorbing layer 10X according to a reference example, the cross-sectional structure of which is shown in Figures 8B and 9B, was similar to the functional components 100 and 100C according to the examples of the present invention in that the light-absorbing layer 10X was provided on a substrate 40 made of stainless steel. The light-absorbing layer 10X had a dark region 30X containing a nickel oxide compound and a light region 20X. As shown in Figure 8B, in Reference Example 1, the light region 20X was composed of a metallized layer 21X and a main portion 22X.

[0039] As shown in Figures 2A and 2B, the film member 10 of the functional component 100 according to Example 1 had a surface shape on the second portion 30 side with independent convex portions. Specifically, the surface shape on the second portion 30 side had a basic structure in which multiple convex portions protruding independently from each other were arranged in the in-plane direction, with the bottoms positioned to surround each convex portion. Furthermore, as shown in the cross-sectional view of Figure 2C, the surface on the Z1 side of the first portion 20 had an uneven structure, and the second portion 30 was provided so as to protrude further toward the Z1 side from the portion of the first portion 20 protruding toward the Z1 side.

[0040] This structure will be explained in detail using Figure 2D. Figure 2D is a diagram in which symbols indicating structural features have been added to Figure 2C. In the cross-sectional view of Figure 2D, the surface on the Z1 side of the first portion 20 of the film-like member 10 is shown as a concave-convex line consisting of a bottom portion B located on the Z2 side and a top portion T protruding from the bottom portion B to the Z1 side. In this concave-convex line, the portion including two bottom portions B aligned in the X direction and a top portion T located between those bottom portions B constitutes a protrusion portion P.

[0041] In the cross-sectional view of FIG. 2D , the second portion 30 was provided on the Z1 side of the protruding portion P of the first portion 20, protruding further to have a summit portion S, and the protruding portion P of the first portion 20 and the second portion 30 constituted a convex portion C of the film-like member 10. In the secondary electron images of the main surface of the film-like member 10 shown in FIGS. 2A and 2B , multiple convex portions C were lined up in the in-plane direction (X-Y in-plane direction). As shown in FIG. 2D , the protruding height (length in the Z direction) of these convex portions C included the protruding height (length in the Z direction) of the second portion 30 having the summit portion S and the protruding height (length in the Z direction) of the protruding portion P of the first portion 20.

[0042] The main surface on the Z1 side of the film-like member 10 having such a structure has a so-called moth-eye structure, and visible light traveling from the Z1 side to the Z2 side of the film-like member 10 enters the gaps between adjacent convex portions C and is absorbed by the walls of the convex portions C, making it difficult for it to be reflected toward the Z1 side. The same is true for light in the wavelength range of 0.8 μm to 2.0 μm (also called "NIR: near-infrared") and infrared light, which are easily absorbed by the film-like member 10. Therefore, the film-like member 10 has a light absorption function and a photothermal conversion function.

[0043] As shown in Figures 3A to 5C, in the film-like member 10 of the functional member 100 according to Examples 2 to 4, similar to Example 1, a plurality of convex portions C each consisting of a protruding portion P of a first portion 20 protruding toward the Z1 side and a second portion 30 provided so as to protrude further toward the Z1 side from the top T side of the protruding portion P of the first portion 20 discretely protrude from the bottom B of the first portion 20, thereby forming a surface shape with independent convex portions.

[0044] 6C , in the film member 10C of the functional component 100C according to Example 5, the shape of the Z1 side of the first portion 20 was less uneven and the degree of protrusion of the protrusion P was low compared to the shapes of the Z1 sides of the first portion 20 according to Examples 1 to 4. Then, the second portion 30C protruded toward the Z1 side from the protrusion P of the first portion 20 with a low degree of protrusion, thereby forming a surface shape of an independent convex portion type.

[0045] Furthermore, in the film member 10C of the functional component 100C of Example 6, as shown in FIG. 7C , the shape of the first portion 20 on the Z1 side was less uneven than the shape of the first portion 20 on the Z1 side of Example 5, and the degree of protrusion of the protrusion P was particularly low. Furthermore, the second portion 30C was provided on the Z1 side of the protrusion P of these gently protruding first portions 20. Therefore, as shown in FIGS. 7A and 7B , in Example 6, the protrusions C generally tended to protrude in a continuous ridge-like manner. Therefore, in the secondary electron image observed in the Z1 direction ( FIG. 7A ), the protrusions C occupied most of the field of view, forming a surface shape with discrete shallow crater-like depressions. Therefore, Example 6 did not have an independent protrusion type, but rather had a surface shape dominated by the protrusions C (approximately a single protrusion cluster).

[0046] From the above, Examples 5 and 6 did not have the structure of the convex portion C that Examples 1 to 4 had (a structure in which the first portion 20 has a plurality of protrusions P, and the convex portion C is composed of the protrusions P and the second portion 30 that is provided to protrude further from the Z1 side), and the convex portion C that protrudes on the Z1 side was substantially composed of the second portion 30.

[0047] 8B , in the light absorbing layer 10X according to Reference Example 1, the thickness of the dark color region 30X was equal to the thickness of the light absorbing layer 10X. Specifically, the dark color region 30X had a thickness equal to the thickness of the light absorbing layer 10X, and the light color region 20X was partially surrounded by the dark color region 30X.

[0048] As shown in FIG. 9B , the light-absorbing layer 10X of Reference Example 2 appears at first glance to have a similar structure to the film-like member 10C of the functional component 100C of Example 5. However, when considered comprehensively, including the surface observation image 8 of FIG. 9A , the structure is different. For example, in FIG. 9B , dark-colored regions 30X appear to be located on the relatively smooth surface of the light-colored region 20X, with a shape that appears as multiple discrete convexities in cross-sectional observation. However, since FIG. 9B is a cross-sectional image 8 of the surface observation image 8 of FIG. 9A , the dark-colored regions 30X that appear as multiple discrete convexities are actually cross-sections of continuous ridges that form the boundaries between adjacent independent concave portions in the surface observation image 8 of FIG. 9A . Therefore, the light-absorbing layer 10X of Reference Example 2 is completely different from the independent convex portion type of Example 5. In this respect, the dark-colored regions 30X of the light-absorbing layer 10X of Reference Example 1 in FIG. 8B are cross-sections of continuous ridges that form the independent concave portion type, as in Reference Example 2.

[0049] 11A is a diagram showing the luminance distribution of a surface observation image 1 according to Example 1 and the result of performing binarization processing by Otsu's method on this luminance distribution. FIG. 11B is a diagram showing a binary image (binary image 1) obtained by performing binarization processing by Otsu's method on the surface observation image 1.

[0050] As shown in Figure 11A, a threshold value was obtained by performing binarization processing using Otsu's method on the brightness distribution of the surface observation image 1 of the film-like member 10, and a first region on the high brightness side based on this threshold value and a second region on the low brightness side based on the threshold value were set. As shown in Figure 11A, the brightness distribution of the secondary electron image 1 of the film-like member 10 having a surface shape with independent convex portions had one peak (first peak Pk1) in the first region and one peak (second peak Pk2) in the second region. The maximum value (maximum frequency) of the first peak Pk1 was smaller than the maximum value (maximum frequency) of the second peak Pk2.

[0051] 11B is obtained by displaying in white pixels having a luminance that corresponds to the first region in the luminance distribution in the surface observation image 1, and displaying in black pixels having a luminance that corresponds to the second region in the luminance distribution. Therefore, in the binary image 1, the region consisting of pixels displayed in white will be referred to as the first region, and the region displayed in black will be referred to as the second region. The same applies to other binary images.

[0052] 11B with Figures 2A to 2D, it was confirmed that the first region (white) includes the sharp portion S of the convex portion C, and the second region (black) includes the bottom portion B. In Figure 11B, a plurality of first regions (white) are discretely present in the second region (black), and the image pattern shown in Figure 11B is considered to reflect the surface shape of an independent convex portion.

[0053] The luminance distributions of surface observation image 2 according to Example 2 to surface observation image 4 according to Example 4 shown in Figures 12A to 14A all have peaks (first peak Pk1, second peak Pk2) in the first region and the second region, respectively, similar to the luminance distribution of surface observation image 1 according to Example 1, and the maximum value of first peak Pk1 is smaller than the maximum value of second peak Pk2, similar to Example 1. Furthermore, binary image 2 according to Example 2 to binary image 4 according to Example 4 shown in Figures 12B to 14B have a plurality of first regions (white) discretely present in the second region (black), similar to binary image 1, and this image pattern is thought to reflect a surface shape with independent convex portions.

[0054] In contrast, the luminance distribution of the surface observation image 5 of Example 5 shown in Figure 15A had a first peak Pk1 and a second peak Pk2, similar to the luminance distribution of the surface observation image 1 of Example 1, but the magnitude relationship of the maximum values ​​of these peaks was different, with the maximum value of the first peak Pk1 being greater than the maximum value of the second peak Pk2. The surface of the film-like member 10C of Example 5 had a relatively low protrusion height of the protrusion P of the first portion 20 compared to the surfaces of the film-like members 10 of Examples 1 to 4. As a result, the surface of the film-like member 10C of Example 5 did not have as clearly independent convex portions as the surfaces of the film-like members 10 of Examples 1 to 4. This is thought to be reflected in the characteristics of the luminance distribution shown in Figure 15A.

[0055] The luminance distribution of the surface observation image 6 shown in FIG. 16A had a peak (first peak Pk1) in the luminance range corresponding to the first region, but unlike the other examples, did not have a peak (second peak Pk2) in the luminance range corresponding to the second region. Furthermore, the binary image 6 according to Example 6 shown in FIG. 16B tended to have the second region (black) discretely present in the first region (white), rather than the first region (white) discretely present in the second region (black). The characteristics of the luminance distribution shown in FIG. 16A and the characteristics of the binary image 6 shown in FIG. 16B are thought to reflect the fact that the surface shape of the film-like member 10C according to Example 6 was not a type with independent convex portions, but rather a surface shape dominated by convex portions C (approximately a single convex portion cluster).

[0056] The luminance distributions of the surface observation image 7 according to Reference Example 1 and the surface observation image 8 according to Reference Example 2 shown in FIGS. 17A and 18A both had a peak in the second region (second peak Pk2) and no peak in the first region (first peak Pk1). The binary image 7 according to Reference Example 1 shown in FIG. 17B , like the binary image 6, tended to have a discrete second region (black) in the first region (white). Furthermore, when comparing the binary image 8 according to Reference Example 2 shown in FIG. 18B with the surface observation image 8 ( FIG. 9A ), Reference Example 2, like Reference Example 1, was an image that tended to have a discrete second region (black) in the first region (white). Therefore, the characteristics of the luminance distributions (having only the second peak Pk2) and the characteristics of the binary images (discrete second regions in the first region) of Reference Examples 1 and 2 are considered to reflect the surface shape of the recess-independent type.

[0057] From these results, when a secondary electron image is obtained by observing the second portion 30 side of the film member 10 of the functional component 100 according to this embodiment in the normal direction (Z direction) of the film member 10 using a scanning electron microscope, and a threshold value is obtained by performing binarization processing by Otsu's method on the brightness distribution of the secondary electron image, if the first region on the high brightness side of the threshold and the second region on the low brightness side of the threshold both have peaks (first peak Pk1 and second peak Pk2), then the surface of the film member 10 on the second portion 30 side is likely to have an independent convexity type shape. Therefore, it was confirmed that it is possible to determine whether the surface of the film member 10 on the second portion 30 side has an independent convexity type shape based on the presence or absence of these peaks.

[0058] It was also confirmed that if the maximum value of the first peak Pk1 is lower than the maximum value of the second peak Pk2, it can be determined that the surface of the second portion 30 of the film-like member 10 has a more stable independent convex shape. If only the first peak Pk1 or the second peak Pk2 is present in the brightness distribution of the secondary electron image of the surface, it can be determined that the film-like member 10 of the functional member 100 according to this embodiment does not have an independent convex surface shape. Thus, it was confirmed that the brightness distribution of the secondary electron image of the surface can clearly distinguish the film-like member 10 of the functional member 100 according to this embodiment from the film-like member 10C of the comparative example and the light-absorbing layer 10X of the member 100X according to the reference example.

[0059] The quantitative characteristics of the film member 10 according to Examples 1 to 4 and the film member 10C according to Example 5 are shown in Table 4 and subsequent Tables. Table 4 shows the quantitative characteristics obtained by image analysis of surface observation image 1 (Example 1) to surface observation image 5 (Example 5).

[0060]

[0061] Fig. 25A is a diagram showing the relationship between the boundary B1 between the first and second regions and the boundary B2 of the Voronoi regions. Fig. 25B is an explanatory diagram of the equivalent circle diameter Φ1 and the equivalent circle diameter Φ2. Fig. 25A and Fig. 25B are both composite images obtained by superimposing an image in which the boundary B1 between the first and second regions of a binary image can be confirmed and an image in which the boundary B2 of the Voronoi regions is shown.

[0062] The luminance distribution of surface observation image 1, which is a secondary electron image according to Example 1, was subjected to binarization processing using Otsu's method to obtain binary image 1, from which the equivalent circular diameter Φ1 (see FIG. 25B) of the first region (white) was determined, and the first length L1, which is the average value of the obtained equivalent circular diameters Φ1, was determined to be 0.82 μm (see Table 4). Comparing secondary electron image 1 with binary image 1, it is clear that the first region (white) represents the tip-side region, including the sharp portion S, of the multiple independent protrusions C in the independent-protrusion surface shape. Therefore, the first length L1 is a parameter related to the average width of the protrusions C on the tip side.

[0063] On the other hand, a Voronoi diagram was obtained by performing Voronoi division on binary image 1 using the center of gravity of the first region as the generating point (see Voronoi diagram 1 in Figure 19A). Note that Figure 19B is a composite image (composite image 1) obtained by overlaying Voronoi diagram 1 shown in Figure 19A with binary image 1 shown in Figure 11B (see Table 1). For the multiple Voronoi regions shown in Voronoi diagram 1, the equivalent circle diameter Φ2 (see Figure 25B) was calculated, and the second length L2, which is the average of the obtained equivalent circle diameters Φ2, was calculated to be 1.28 μm (see Table 4). Comparing secondary electron image 1 and cross-sectional observation image 1 with binary image 1, it is believed that the boundaries of the Voronoi regions roughly correspond to the lines connecting the bases B that form the boundaries of multiple independent convex portions C in the convex-portion-independent surface shape. Therefore, the second length L2 is a parameter related to the average width of the convex portions C.

[0064] In Examples 2 to 4 of the present invention and Comparative Example 5, the first length L1 and the second length L2 were calculated in the same manner as in Example 1. Specifically, in Examples 2 to 4 of the present invention, the first length L1 was calculated from the binary image of surface observation image 2 (binary image 2) and the binary image of surface observation image 4 (binary image 4) shown in Figs. 12B to 14B . In Comparative Example 5, the first length L1 was calculated from the binary image of surface observation image 5 (binary image 5) shown in Fig. 15B (see Table 4). In Examples 2 to 4 of the present invention, the second length L2 was calculated from the Voronoi diagram of binary image 2 (Voronoi diagram 2) and the Voronoi diagram of binary image 4 (Voronoi diagram 4) shown in Figs. 20A to 22A . In Comparative Example 5, the second length L2 was calculated from the Voronoi diagram of binary image 5 (Voronoi diagram 5) shown in Fig. 23A (see Table 4).

[0065] As shown in FIG. 16B, the binary image (binary image 6) of Comparative Example 6 contained continuous first regions (white), so the equivalent circle diameter Φ1 could not be calculated. Therefore, the first length L1 was not calculated for Comparative Example 6. Furthermore, as shown in FIG. 24A, the Voronoi diagram (Voronoi diagram 6) of Comparative Example 6 contained only two Voronoi regions, so the second length L2 was not calculated for Comparative Example 6. FIGS. 20B to 24B show composite images (composite images 2 to 6) obtained by overlaying binary images 2 to 6 shown in FIGS. 12B to 16B, respectively, with Voronoi diagrams 2 to 6 shown in FIGS. 20A to 24A, respectively (see Table 1).

[0066] Therefore, L2 / L1 is related to the average width of the convex portions C divided by the average width of the tip ends of the convex portions C, and the larger this value, the narrower and more pointed the tip ends of the convex portions C will be in cross section. Therefore, this L2 / L1 is defined as the average sharpness Ps. When the film member 10 of the functional member 100 according to this embodiment has a ratio of 1.3 or more, it is easy to obtain good light absorption and photothermal conversion functions.

[0067] Binary image 1 and Voronoi diagram 1 were obtained from surface observation image 1, and two equivalent circle diameters Φ1 and Φ2 were calculated for each convex portion from these diagrams. The average sharpness Ps calculated from these equivalent circle diameters Φ1 and Φ2 was 1.55, as shown in Table 4. Binary image 5 was obtained from binary image 2 and Voronoi diagram 5 from Voronoi diagram 2 from surface observation images 2 to 5, and the average sharpness Ps was calculated in the same manner. The results are shown in Table 4 and FIG. 26A.

[0068] 26A is a graph showing the relationship between the average sharpness Ps and the average NIR total reflectance Rt. As shown in Table 4 and FIG. 26A, the film member 10 of the functional member 100 according to the present invention (Examples 1 to 4) has an average sharpness Ps on the second portion 30 side of 1.3 or more, thereby stably achieving an average NIR total reflectance Rt of 2% or less. FIG. 26B is a graph showing the relationship between the phosphorus content ratio Rp and the average sharpness Ps. FIG. 26B shows that the phosphorus content ratio Rp and the average sharpness Ps have a positive correlation. This tendency suggests that the average sharpness Ps can be controlled by adjusting the phosphorus content ratio Rp.

[0069] As described above, the film portion 10 of the functional component 100 according to Example 1 satisfies all of the following: average NIR total reflectance Rt≦2%, phosphorus content ratio Rp≧1, and average sharpness Ps≧1.3. Examples 2 to 4, which are examples of the present invention, also satisfy all of these characteristics.

[0070] To examine the sharpness in more detail, the equivalent circular diameter Φ1 of all first regions and the equivalent circular diameter Φ2 of the Voronoi regions corresponding to the first regions were determined from the binary images and Voronoi diagrams according to Examples 1 to 5, and a frequency distribution of the individual sharpness Pi calculated by Φ2 / Φ1 was created. The frequency distribution of the obtained individual sharpness Pi is shown in Figure 27. Note that in the frequency distribution shown in Figure 27, to facilitate relative comparison, the vertical axis represents the relative frequency obtained by dividing the frequency of each class by the total number of Voronoi regions shown in each Voronoi diagram, and the baseline of each frequency distribution is displayed shifted by 0.2 in relative frequency increments.

[0071] Furthermore, the mode, mean value, and standard deviation of the individual sharpness index Pi were calculated from these frequency distributions, and the coefficient of variation, defined as standard deviation / mean value, was calculated. These results are shown in Table 5.

[0072]

[0073] The frequency distribution of the individual sharpness Pi in Examples 1 to 4, which are examples of the present invention, and Example 5, which is a comparative example, has a relatively clear peak, and it was confirmed that the mode of the individual sharpness Pi gradually decreases to 1 from Example 1 to Example 5. This trend was similar to that of the average sharpness Ps. Here, a sharpness of "1" means that the object is not sharp.

[0074] Furthermore, the film portions 10 according to Examples 1 and 2, which have high sharpness and a coefficient of variation of 0.4 or less, have excellent light absorption and photothermal conversion properties even when thin, have relatively small variations in the individual sharpness Pi, and are unlikely to have excessively deep recesses. Therefore, it is not necessary to increase the thickness of the first portion 20 to prepare for excessively deep recesses, and an increase in the heat capacity of the film member 10 can be suppressed. Therefore, it was suggested that the film portions 10 according to Examples 1 and 2 are particularly effective as photothermal conversion members.

[0075] The above-described embodiments are provided to facilitate understanding of the present invention, but are not intended to limit the present invention. Therefore, the elements disclosed in the above embodiments are intended to encompass all design modifications and equivalents within the technical scope of the present invention. For example, in the above embodiment, the main portion 22 of the first part 20 is formed by nickel-phosphorus electroless plating, but this is not limiting and the main portion 22 may be formed by nickel-phosphorus electrolytic plating.

[0076] 100, 100C: Functional member 100X: Member 10, 10C: Film-like member 10X: Light absorbing layer 20: First portion 20X: Light color region 21: Strike plating layer 21X: Metallized layer 22, 22X: Main portion 30, 30C: Second portion 30X: Dark color region 40: Base material C: Convex portion B: Bottom portion T: Top portion P: Protrusion portion S: Sharp portion B1: Boundary between first and second regions B2: Boundary of Voronoi region Φ1: Equivalent circle diameter of first region Φ2: Equivalent circle diameter of Voronoi region L1: Average value of Φ1 L2: Average value of Φ2

Claims

1. A film-like member comprising a film-like first portion containing nickel and phosphorus, and a second portion located on one main surface side of the first portion and containing nickel, oxygen, and phosphorus, wherein the phosphorus content in the second portion is equal to or greater than the phosphorus content in the first portion, and when a secondary electron image is obtained by observing the main surface of the film-like member on the side of the second portion in the normal direction with a scanning electron microscope, and a threshold is determined by performing binarization processing using Otsu's method on the brightness distribution of the secondary electron image, both a first region on the high brightness side of the threshold and a second region on the low brightness side of the threshold in the brightness distribution have peaks, A film-like member characterized in that, when the secondary electron image is binarized using the threshold value to obtain a binary image, and a first length L1, which is the average value of the circular equivalent diameter Φ1 of the first region in the binary image, and a second length L2, which is the average value of the circular equivalent diameter Φ2 of the Voronoi region in a Voronoi diagram obtained by performing Voronoi division on the binary image using the center of gravity of the first region as the generating point, are calculated, the average sharpness Ps defined by L2 / L1 is 1.3 or more.

2. A film member according to claim 1, wherein the average value Rt of the total reflectance when the main surface on the second portion side is irradiated with light in the wavelength range of 0.8 μm to 2.0 μm is 2% or less.

3. A membrane member according to claim 1, wherein the phosphorus content in the second portion is 4.5 mass % or more and 7 mass % or less.

4. A film-like member as described in claim 3, wherein the first portion is a nickel-phosphorus alloy, the second portion is an oxide of the nickel-phosphorus alloy continuous with the first portion, and the phosphorus content ratio Rp of the second portion to the first portion is 1.0 or more.

5. A film-like member according to claim 1, wherein the coefficient of variation of the individual sharpness Pi calculated from Φ2 / Φ1, which is the circle-equivalent diameter Φ1 and the circle-equivalent diameter Φ2, is 0.4 or less.

6. A membrane member according to claim 3, wherein the first portion includes nickel phosphorus plating, and the second portion includes a modified portion of the nickel phosphorus plating that is continuous with the first portion.

7. A film member according to claim 6, wherein the modified portion is an oxide of the nickel-phosphorus plating, and the ratio of the phosphorus content of the second portion to the first portion is 1.0 or more.

8. A membrane member according to claim 1, wherein the average thickness of said first portion is 6 μm or less.

9. The film-like member according to claim 8, wherein the average thickness of said second portion is 2 μm or less.

10. A functional component comprising a substrate and a film-like member according to any one of claims 1 to 9 provided on the substrate, wherein the average value Rt of the total reflectance when light in the wavelength range of 0.8 μm to 2.0 μm is irradiated onto the film-like member side is 2% or less.

Images