JPH03115583A - Light absorber and production thereof - Google Patents

Abstract

PURPOSE:To obtain a light absorber transducing light energy into heat energy by forming an Ni plating layer as a stress relieving layer on the surface of a thin base material of Cu, etc., further forming an Ni-P alloy plating layer by electroless plating and blackening the alloy plating layer by oxidation. CONSTITUTION:When a light absorber used to transduce light energy into heat energy is produced, one side of Cu foil is electroplated with Ni to form an Ni plating layer as a stress relieving layer and an Ni-P alloy plating layer is formed on the Ni layer by electroless plating. The plated foil is washed and treated with a soln. contg. NaNO3 and H2SO4 to blacken the Ni-P alloy plating layer. The Cu foil 2 with the resulting black coating film 3 as the light absorber 1 is fixed on a substrate 4 with an adhesive 5 and a thermocouple 6 is fitted to the rear side of the substrate 4. light energy is transduced into heat energy by the light absorber 1 and output as an electric signal through the thermocouple 6.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a light absorber used in optical sensors, etc., and in particular to an electroless nickel-phosphorus plating with a black coating applied to the surface of a thin base material. The present invention relates to a light absorber having a layer and converting light energy incident on the black film into thermal energy, and a method for manufacturing the same. [Prior Art] In order to use a light absorber for measuring optical power, as shown in FIG. It is fixed to the substrate 4 with an adhesive 5, a thermocouple element 6 is provided on the back side of the substrate 4, the light energy is converted into thermal energy by the light absorber, and this thermal energy is converted into an electric signal by the thermocouple element. It is outputting. This all-black coating formed on the surface of the substrate is prone to peeling off due to mechanical vibration or friction, and also has the problem of absorbing moisture and increasing reflectance under high-temperature conditions, which poses many practical difficulties. In contrast, a black film developed by one inventor (patent application 1986)
-231761 and Japanese Patent Application No. 63-231760) is obtained by forming an electroless plating film of nickel-phosphorous alloy and oxidizing it, and its total reflectance is 0.2%. It has excellent performance in that it has extremely low wavelength dependence in its light absorption characteristics, and has sufficient strength, so it is difficult to peel off due to mechanical vibration or friction, is not affected by ambient temperature conditions, and is resistant to moisture. It has the advantage of being difficult to absorb. [Problem to be Solved by the Invention 1] However, in order to use such a nickel-phosphorus black film as a light absorber to increase its sensitivity and reduce its thermal time constant, it is necessary to minimize the heat capacity of the light absorber. However, it is necessary to improve heat conduction, and the base material to which electroless nickel-phosphorus plating is applied also needs to be thin. In such a case, the electroless plated film generates tensile stress during the plating process, causing the problem that the base material warps upward. When a glass plate is used as the base material, the electroless nickel/phosphorous coating peels off from the glass substrate. When a black film is used in an optical power sensor, warping or peeling of the sensor surface is not preferable because it causes problems in surface sensitivity distribution and thermal time constant. An object of the present invention is to provide a light absorber free from such warpage and a method for manufacturing the same. [Means for Solving the Problems] The present invention has found that warping of the base material due to the tensile stress of the electroless nickel-phosphorus plating layer can be prevented by providing a stress relaxation layer between the base material and the plating layer. , to provide a light absorber that does not cause warping or peeling. That is, the present invention provides a light absorber that has an electroless nickel phosphorus plating layer treated with a black film on the surface of the base material and converts light energy incident on the black film into thermal energy. - A light absorber characterized by having a stress-relaxing plating layer interposed between the phosphor plating layer and the phosphor plating layer. The stress-relaxing plating layer of the light absorber of the present invention has an effect that the tensile stress of the nickel-phosphorous electroless plating film applied to its outer surface does not reach the base material, and has substantially no internal stress. It is a plating layer that has compressive stress corresponding to the bow tension stress inherent in a metal plating layer or a nickel-phosphorus electroless plating layer, and is particularly preferably an electrodeposited layer obtained from a compressive stress electrolytic bath. As an electrolytic bath for obtaining such a compressive stress electrodeposited layer, for example, a nickel sulfamate bath containing sodium laurate,
Addition of sulfur-containing organic substances such as saccharin, naphthalene disulfonic acid, and naphthalene trisulfonic acid can also produce compressive stress at appropriate concentrations. The thickness of the stress relaxation layer of the present invention is preferably as thin as possible as long as the effect can be obtained, and is generally 10 to 50B. The electroless nickel-phosphorous layer on the stress relaxation layer has a phosphorus content of 7-10%, a thickness of 15-80II11, and a black film is formed on its surface by oxidation treatment. The black coating described in Japanese Patent Application No. 63-231761 and Japanese Patent Application No. 63-231760 is excellent as a photosensor due to its light absorption and wavelength characteristics. The base material of the light absorber of the present invention has a normal thickness of 10 to 50
A thin film of copper or gold with a thickness of 11 m is used, but materials obtained by electrodepositing or vapor depositing these metals on glass or ceramics are also used. The light absorber of the present invention is manufactured by electrolytically or electrolessly plating a stress relaxation layer on a thin base material such as a copper thin film, and then applying nickel strike plating if necessary.
Electroless plating of nickel and phosphorus is carried out. After blackening the surface of the electroless nickel and phosphorus plating layer, it is washed with water and dried.
Cut out the sensor element of the required shape and glue it onto the sensor substrate. Another method is to mask the required shape on a substrate made of glass, ceramics, etc., sequentially stack nickel, copper, stress relaxation layer, and electroless nickel/phosphorus plating layer, and then blacken the surface. good. [Example J Example 1 One side of a 6IIIlφ, 2O4m thick copper foil was masked, and an electrolytic plating solution with the primary composition was used as a stress relaxation layer on the other side, at a solution temperature of 50°C and a current density of 3A/dm. ” and thickness 1
A 5μI nickel film was plated. Nickel sulfamate 300 g/j Nickel chloride 20 g 71 Boric acid
40 g/j Sodium lauryl sulfate: l g/j Saccharin
When the plated layer obtained at 5 g/l was measured using a surface roughness meter, as shown in FIG. 1, the electrodeposited layer side was warped in a convex shape of about 8011 m due to the compressive stress of the electrodeposited layer. Next, using the following electroless nickel plating solution, the solution temperature was 90°C.
C. for 2 hours to deposit an electroless nickel-phosphorous alloy film with a thickness of 5011 mm on the electrolytic nickel plating layer. Nickel sulfate [6g/j Sodium phosphinate 32 geldl-malic acid
67 g/l malonic acid
31 g/l The obtained laminated film was washed with water, dried, and measured with a surface roughness meter. As shown in FIG. 2, substantially no surface warpage was observed. This laminated film was washed with water, treated with a solution containing 300 g/j sodium nitrate and 552 g/l sulfuric acid at a temperature of 50°C for 2 minutes to blacken the nickel and phosphorus bites, and this was washed with water and dried to blacken. A light absorber material having a coating was obtained. The obtained light absorber has a total reflectance of 320 to 2200.
It was 0.1:l to 0.17 in the na+ wavelength range. The black coated surface was resistant to friction, and no warpage was observed at all. Comparative Example 1 In Example 1, an electroless nickel-phosphorus alloy layer was provided without electrolytic plating as a stress relaxation layer, and a black film treatment was performed. The obtained light absorber was a disk with a diameter of 6 m and was warped concavely on the black coating side, and as shown in Figure 3, the difference in dent between the outer periphery and the center was 80IIll when measured using a surface roughness meter. . [Effects of the Invention 1] Since the light absorber of the present invention has a stress relaxation layer interposed between the base material and the nickel-phosphorous alloy layer, there is no warping, and when used as an optical power sensor element. Since there is no gap between the substrate and the sensor element, measurement errors due to the incident position of the incident light do not occur.

[Brief explanation of drawings]

Figure 1 is a measurement graph of surface warpage at an intermediate stage when a stress relaxation layer is electrodeposited on copper foil, and Figure 2 is a measurement graph of warpage when an electroless nickel phosphorus plating layer is further applied to the surface. It is a graph. FIG. 3 is a measurement graph of warpage in a case where the stress relaxation layer of FIG. 1 was not provided and an electroless nickel-phosphorus plating layer was directly applied on the copper foil. FIG. 4 is a sectional view showing the structure of an optical power sensor using a light absorber. l...Light absorber, 2...Base material, 3...Coating, 4...
...Substrate, 5.Adhesive, 6.--Thermocouple.

Claims (2)

[Claims] (1) In a light absorber that has an electroless nickel-phosphorus plating layer treated with a black coating on the surface of the base material and converts light energy incident on the black coating into thermal energy, the base material layer and the nickel-phosphorus A light absorber characterized by having a stress-relaxing plating layer interposed between the plating layer and the plating layer. (2) After applying a plating layer containing compressive stress to the base material layer, and then applying a nickel/phosphorus plating layer by an electroless method, the nickel/phosphorus plating film is oxidized to form a black film. A method for producing a characteristic light absorber.