JP4412024B2 - Ceramic substrate for mounting photoelectric conversion element and manufacturing method thereof - Google Patents

Description

  The present invention relates to a ceramic substrate for mounting a photoelectric conversion element on which a photoelectric conversion element such as an LED is mounted.

  Conventionally, photoelectric conversion elements such as light-emitting diodes (LEDs) have been used for applications such as electronic device indicators, but in recent years their luminous efficiency and luminance have improved, and the luminance per unit input has been incandescent. LEDs that are superior to lamps have been developed, and by combining a plurality of LEDs, it has become possible to apply them to lighting applications.

  In addition, since LEDs have a long service life, they have the advantage of maintenance such as labor saving of lamp replacement, and illumination that does not emit infrared rays that damage fresh food due to the narrow emission wavelength range (for example, show in a fish shop) For example), and can be used for lighting that does not emit ultraviolet light that causes deterioration of the work of art (eg, museum lighting).

  In addition, photoelectric conversion elements such as LEDs are also used in optical exchanges, optical interconnection devices, and the like, and contribute to realization of a large communication capacity and high speed.

Such a photoelectric conversion element is often used by being mounted on a substrate in order to be coupled with electric wiring. As a substrate for mounting a photoelectric conversion element, as disclosed in Patent Document 1, for example, it is proposed to use a ceramic substrate made of alumina, aluminum nitride, silicon carbide, beryllium oxide, or the like.
JP 2000-357770 A

  When the ceramic substrate as described above is mounted with a photoelectric conversion element, if a material that absorbs light emitted from the photoelectric conversion element is used, light emitted from the photoelectric conversion element mounted on the substrate is actually observed. The light emission brightness is reduced. In addition, it is necessary to provide a conductor wiring made of a metal or the like for connecting the photoelectric conversion element and the electric wiring on the ceramic substrate. For this reason, it is necessary to provide excellent adhesion strength between the ceramic substrate and the metal film. is there.

  However, conventionally, no one has been found that imparts high adhesion between a ceramic substrate and a metal while simultaneously imparting high light reflectivity to the ceramic substrate.

  The present invention has been made in view of the above points, and improves the light emission efficiency by reflecting the light emitted from the photoelectric conversion element with high efficiency while ensuring sufficient adhesion strength with the conductor wiring. An object of the present invention is to provide a ceramic substrate for mounting a photoelectric conversion element and a method for manufacturing the same.

  The ceramic substrate for mounting a photoelectric conversion element according to the present invention contains alumina and silica, and the alumina content is higher than that of the base material 1 on the surface of the base material 1 made of a material having a silica content of 2% by mass or more. A coating layer 2 made of a material having a high rate is formed, and a metal conductor layer 3 is formed on the surface of the coating layer 2. As a result, high adhesion between the coating layer 2 and the metal conductor layer 3 can be obtained, the adhesion strength of the metal conductor layer 3 can be improved, and high light reflectivity is maintained on the surface of the substrate 1. Is done.

In the ceramic substrate for mounting a photoelectric conversion element, the surface of the substrate 1 made of a material containing alumina and silica and having a silica content of 2% by mass or more is partially irradiated with electromagnetic waves. A coating layer 2 made of a material having an alumina content higher than that of the substrate 1 and a silica content lower than that of the substrate 1 is formed on the portion irradiated with the electromagnetic wave, and the metal conductor layer 3 is formed on the surface of the coating layer 2 . In this case, since the metal conductor layer 3 is formed on the surface of the coating layer 2, the peel strength of the metal conductor layer 3 can be improved, and the coating layer 2 is formed at a portion where the metal conductor layer 3 is not formed. The base material 1 which is not formed is exposed, and higher light reflectivity is maintained by the exposed surface of the base material 1.

Moreover, the manufacturing method of the ceramic substrate for mounting a photoelectric conversion element according to the present invention includes the following steps (a) to (c).
(A) The base material formation process which forms the base material 1 which consists of a material which contains an alumina and a silica and the content rate of a silica is 2 mass% or more.
(B) By removing silica in the surface layer of the base material 1 formed by the base material forming step and leaving alumina, the alumina content is higher than the base material 1 and the silica content is on the surface of the base material 1. A silica removing step for forming the coating layer 2 made of a low material.
(C) A metal conductor layer forming step of forming the metal conductor layer 3 on the surface of the coating layer 2 formed by the silica removing step.

  By passing through such a process, the surface of the base material 1 made of a material containing alumina and silica as described above and having a silica content of 2% by mass or more is more alumina than the base material 1. A ceramic substrate for mounting a photoelectric conversion element in which the coating layer 2 made of a material having a high content and a low silica content is formed and the metal conductor layer 3 is formed on the surface of the coating layer 2 can be manufactured. Moreover, since the coating layer 2 is formed by removing silica from the surface layer of the substrate 1, the coating layer 2 is formed with better adhesion than when the coating layer 2 is additionally formed on the surface of the substrate 1. And the number of processes can be reduced.

  In this method for producing a ceramic substrate for mounting a photoelectric conversion element, silica in the surface layer of the substrate 1 can be removed by immersing the substrate 1 in an alkaline solution in the silica removing step. In this way, the coating layer 2 can be easily formed on the surface of the base material 1 having a complicated three-dimensional shape, and easily by controlling the concentration, temperature, immersion time, etc. of the alkaline solution. The thickness of the coating layer 2 can be controlled.

  In the silica removal step, the silica in the surface layer of the substrate 1 can be removed by heat-treating the substrate 1 at a temperature equal to or higher than the melting point of silica. In this manner, the coating layer 2 can be formed by removing the silica by elution of the silica by heat treatment, and the elution trace after the silica is eluted is buried by the growth of alumina crystal grains accompanying heating, and the coating layer The surface of 2 is formed smoothly, whereby the metal conductor layer 3 can be formed with high accuracy.

  In the silica removal step, the silica at the site irradiated with the electromagnetic wave can be removed by irradiating the surface of the substrate 1 with the electromagnetic wave. In this case, only the surface layer portion can be efficiently heated by the heat treatment using electromagnetic waves, the processing time can be shortened and the cost can be reduced, and it is easy to form the coating layer 2 only at a desired portion. It is.

  According to the present invention, a ceramic substrate for mounting a photoelectric conversion element capable of improving the light emission efficiency by reflecting light emitted from the photoelectric conversion element with high efficiency while ensuring sufficient adhesion strength of the metal conductor layer is obtained. be able to.

  Hereinafter, the best mode for carrying out the present invention will be described.

  The ceramic substrate according to the present invention is the surface of the coating layer 2 in the substrate (mother substrate 4) in which the ceramic coating layer 2 having a higher alumina content than the base material 1 is formed on the surface of the ceramic substrate 1. Further, the metal conductor layer 3 is formed.

  The base material 1 has a function of reflecting light emitted from a photoelectric conversion element, contains alumina and silica, and is formed of a material having a silica content of 2% by mass or more. It has high light reflectivity. The upper limit of the silica content is not particularly limited, but the upper limit of the silica content is preferably 8% by mass from the viewpoint of ensuring sufficient adhesion strength. In addition, it is preferable that the substrate 1 does not contain components other than silica and alumina, but a small amount of additive components and components that are inevitably mixed are allowed, and in such cases other than silica and alumina. It is preferable that the content rate of this component is 1 mass% or less.

  The coating layer 2 has a function of forming the metal conductor layer 3 with good adhesion by forming the metal conductor layer 3 on the surface thereof, and has a higher alumina content than the base material 1 and a silica content. By forming with a low material, the metal conductor layer 3 is formed with higher adhesion strength than when the metal conductor layer 3 is directly formed on the surface of the substrate 1.

  The higher the alumina content of the coating layer 2, the higher the adhesion strength with the conductor wiring, and it is particularly desirable that this content is 99% by mass or more. The alumina content in the coating layer 2 is preferably as high as described above, and ideally is 100% by mass.

  Although the said coating layer 2 may be formed in the whole surface of the base material 1 like FIG.1 (c), it can be partially formed in the surface of the base material 1 (refer FIG.2 (b)). ).

  The coating layer 2 is preferably formed so that its thickness is in the range of 1 to 250 μm. In this case, when the light emitted from the photoelectric conversion element is reflected at the portion where the coating layer 2 is formed, the light passes through the coating layer 2 and has a high reflectance at the interface between the coating layer 2 and the substrate 1. In addition, when the metal conductor layer 3 is formed on the surface of the coating layer 2 having such a thickness, a very high adhesion strength can be obtained.

  When the coating layer 2 is partially formed on the substrate 1, as shown in FIG. 2 (b), the coating layer 2 is formed at a site where the metal conductor layer 3 is formed. It is preferable to form the metal conductor layer 3 on the surface. In this case, since the metal conductor layer 3 is formed through the coating layer 2, it has high adhesion strength. Further, when the coating layer 2 is formed on the entire surface of the substrate 1, the light L emitted from the photoelectric conversion element once passes through the coating layer 2 as shown in FIG. The light is reflected at the interface with the coating layer 2 and causes a slight loss of light when transmitted through the coating layer 2. However, when the coating layer 2 is partially formed at a portion where the metal conductor layer 3 is formed, FIG. As shown in b), on the surface of the ceramic substrate for mounting a photoelectric conversion element, the surface of the base material 1 having a high light reflectivity is exposed over a wide range in a portion where the metal conductor layer 3 is not formed. Therefore, the light L emitted from the photoelectric conversion element can be directly reflected on the surface of the substrate 1 to obtain high luminous efficiency.

  A method for manufacturing such a ceramic substrate for mounting a photoelectric conversion element will be described.

  In the manufacture of a ceramic substrate for mounting a photoelectric conversion element, first, a substrate 1 made of a material containing alumina and silica and having a silica content of 2% by mass or more is formed (substrate forming step; FIG. 1 ( a)).

  In this base material forming step, an appropriate method is used. For example, ceramic powder and an appropriate binder are mixed with a kneader such as a heating kneader, and the obtained molding material is subjected to CIM (ceramic injection molding). The base material 1 can be formed by forming it into a desired shape by applying it, heating and degreasing it, and then firing it. The composition of the binder is not particularly limited, and it is possible to appropriately select and use one that can form the molding material and can be decomposed and volatilized by heat degreasing. For example, polystyrene 60% by mass, paraffin wax What has a composition of 20 mass% and stearic acid 20 mass% can be used. Moreover, although the usage-amount of a binder is also adjusted suitably, it is preferable to make a binder into the range of 15-25 mass parts with respect to 100 mass parts of ceramic powder.

  Next, the coating layer 2 is formed on the surface of the obtained base material 1 to obtain the mother substrate 4 (see FIG. 1B). The coating layer 2 can be formed by an appropriate technique. For example, the coating layer 2 may be formed by forming a ceramic powder for forming the coating layer 2 on the surface of the base material 1 and firing it.

  Further, by removing silica in the surface layer of the substrate 1 formed by the above-described substrate forming step and leaving alumina, the alumina content is higher than the substrate 1 on the surface of the substrate 1 and the silica content is The coating layer 2 made of a low-quality material may be formed (silica removal step). In particular, when the coating layer 2 is formed by such a silica removal step, the coating layer 2 can be formed with better adhesion than when the coating layer 2 is additionally formed on the surface of the substrate 1, and the number of steps can be reduced. It can also be reduced.

  Next, the metal conductor layer 3 is formed at a predetermined position on the surface of the coating layer 2 in the mother substrate 4 (metal conductor layer forming step; see FIG. 1C).

  In forming the metal conductor layer 3, an appropriate method can be adopted.

  A preferred example of a method for forming the metal conductor layer 3 is shown in FIG. First, a conductive thin film 5 made of copper or the like is formed on the surface of the mother substrate 4 by physical vapor deposition or the like, and this conductive thin film 5 is irradiated with an electromagnetic wave such as a laser beam to partially remove the conductive thin film 5. At this time, the region 6 surrounded by the portion from which the conductor thin film 5 has been removed is made to have a desired conductor pattern (see FIG. 3A).

  Next, the metal conductor layer 3 is formed by thickening the conductive pattern region 6 by electrolytic plating. At this time, the conductor thin film 5 which is not thickened remains (see FIG. 3B).

  The remaining conductor thin film 5 is electrically insulated from the metal conductor layer 3 and may be left as it is, or may be removed by performing a soft etching process (FIG. 3). (See (c)).

  When forming the metal conductor layer 3 as described above, it is preferable to clean the surface of the mother substrate 4 in advance by heat treatment or the like when the conductor thin film 5 is formed. In order to improve the adhesion between the metal conductor layer 3 and the mother substrate 4, it is also preferable to perform a surface treatment such as plasma treatment in advance. The conductor thin film 5 can be formed by adopting an appropriate method, but can be formed by DC magnetron sputtering using, for example, copper as a target. At this time, the thickness of the conductive thin film 5 is desirably formed in the range of 100 to 1000 nm.

  Further, for partial removal of the conductor thin film 5 by electromagnetic waves, for example, a third harmonic of a YAG laser (THG-YAG laser) can be used.

  Moreover, at the time of formation of the metal conductor layer 3 by electrolytic plating, for example, an electrolytic copper plating process can be performed to form the copper metal conductor layer 3. The thickness of the metal conductor layer 3 is preferably in the range of 5 to 20 μm.

  An appropriate method can be adopted as a method for removing silica in the silica removing step in the above-described ceramic substrate manufacturing process. For example, the silica in the surface layer of the substrate 1 is removed by immersing the substrate 1 in an alkaline solution. be able to. As this alkaline solution, an appropriate one such as an aqueous sodium hydroxide solution is used. When the coating layer 2 is formed in this manner, the coating layer 2 can be easily formed on the surface of the base material 1 having a complicated three-dimensional shape, and the concentration, temperature, and immersion time of the alkaline solution. By controlling the above, the thickness of the coating layer 2 can be easily controlled.

  Moreover, the coating layer 2 can also be formed by removing the silica in the surface layer of the base material 1 by heat-treating the base material 1 at a temperature equal to or higher than the melting point of silica. For example, when the base material 1 is fired in the base material forming step, the base material 1 is produced by firing at a temperature lower than the melting point of silica (1610 ° C.), and then the heating temperature is raised to the melting point of silica or higher. Thus, silica is eluted from the surface layer of the substrate 1 to form the coating layer 2. At this time, in the surface layer of the substrate 1, elution traces are formed by elution of silica, but at the same time, growth of alumina crystal grains occurs by heating to fill the elution traces. The surface of the layer 2 is formed smoothly without being roughened, and can be formed with high accuracy when the metal conductor layer 3 is formed on the surface of the coating layer 2.

The heat treatment conditions for elution of silica are adjusted as appropriate. However, in order to ensure the elution of silica, the heating temperature is preferably set to 1620 ° C. or higher. to prevent damage, it is not preferable that the heating temperature is 1700 ° C. or less.

  In addition, by irradiating the surface of the base material 1 obtained in the base material forming step with an electromagnetic wave such as a laser beam, silica is eluted from the surface layer of the base material 1 at the site irradiated with the electromagnetic wave. The coating layer 2 can also be formed at any location on the surface of the substrate 1. The example shown in FIGS. 4 and 5 shows an example in which the metal conductor layer 3 is formed in the same manner as that shown in FIG. 3 after the coating layer 2 is formed at an arbitrary location. First, FIG. As shown in FIG. 2, the coating layer 2 is partially formed by irradiating the surface of the base material 1 obtained in the base material forming step with an electromagnetic wave w such as a laser beam to obtain the mother substrate 4. For elution of silica by irradiation with the electromagnetic wave w, for example, a third harmonic of a YAG laser (THG-YAG laser) can be used. The irradiation condition of the electromagnetic wave w is appropriately adjusted. For example, in the case of a THG-YAG laser, irradiation is performed under conditions of an average output of 4 to 7 W, a spot diameter of 20 to 100 μm, and a scanning speed of 50 to 400 mm / sec. By performing, the coating layer 2 can be formed in any location of the substrate 1.

  Next, a conductor thin film 5 made of copper or the like is formed on the surface of the mother substrate 4 including the surface of the coating layer 2 by physical vapor deposition or the like (see FIG. 4B), and laser light or the like is formed on the conductor thin film 5. The conductive thin film 5 is partially removed by irradiating the electromagnetic wave (see FIG. 4C). At this time, the region 6 surrounded by the portion from which the conductor thin film 5 has been removed is formed in a desired conductor pattern. This region 6 is formed on the surface of the coating layer 3.

  Next, the metal conductor layer 3 is formed by thickening the conductor pattern-shaped portion by electrolytic plating. At this time, the conductive thin film 5 which is not thickened remains (see FIG. 5A).

  The remaining conductor thin film 5 is electrically insulated from the metal conductor layer 3 and may be left as it is, or may be removed by performing a soft etching process (FIG. 5). (See (b)).

[Example 1]
The following materials were put into a heating kneader so as to have a mass ratio of powder raw material: binder = 100: 20 and kneaded to prepare pellets.

Powder raw material composition-Alumina powder (manufactured by Sumitomo Chemical Co., Ltd., "AES-11", average particle diameter φ 0.5 µm, purity 99.0%) ... 96 parts by mass-Silica powder (manufactured by Admatechs, "SO-C2", Particle size 0.4 to 0.6 μm) ... 4 parts by mass Binder composition ・ Polystyrene ... 60% by mass
・ Paraffin wax: 20% by mass
・ Stearic acid: 20% by mass.

By using the above pellets and injection molding under the conditions of a material temperature of 180 ° C., a mold temperature of 20 ° C., and an injection rate of 40 cm ³ / s on an injection molding machine (manufactured by FANUC, “ROBOSHOT-α50iAp”), 40 mm × A rectangular flat plate shaped product having a size of 30 mm × 2 mm was obtained.

  This molded product was degreased by heating from room temperature to 550 ° C. over 72 hours.

  Next, the furnace temperature was raised from room temperature to 1600 ° C. over 10 hours, and then kept at 1600 ° C. for 1 hour to sinter.

  The obtained base material 1 was immersed in an aqueous sodium hydroxide solution having a concentration of 20% and a temperature of 30 ° C., so that the silica in the surface layer portion was eluted to form the coating layer 2. At this time, a plurality of mother substrates 4 having coating layers 2 of various thicknesses were produced by changing the immersion time in the aqueous sodium hydroxide solution.

(Reflectance measurement)
About the obtained mother substrate 4, the reflectance with respect to the light of wavelength 470nm was measured using the ultraviolet and visible spectrophotometer (the Shimadzu Corporation make, "UV3100PC").

(Surface roughness)
About the obtained mother board | substrate 4, the arithmetic mean roughness (Ra) was measured using the non-contact three-dimensional measuring machine (The product made from Mitaka optical device, "NH-3N").

(Peel strength)
The obtained mother substrate 4 was heated at 1000 ° C. for 1 hour to clean the surface, and then the surface was subjected to plasma treatment, and a conductor thin film 5 was formed using a DC magnetron sputtering apparatus. That is, first, the mother substrate 4 was set in a chamber of the plasma processing apparatus, the inside of the chamber was depressurized to about 10 ⁻⁴ Pa, and then preheated at 150 ° C. for 3 minutes. Thereafter, oxygen gas is circulated in the chamber, the gas pressure in the chamber is controlled to about 10 Pa, and in this state, a 1 kW high-frequency voltage (RF: 13.56 MHz) is applied between the electrodes to generate plasma. For 300 seconds to perform plasma treatment. Next, the pressure in the chamber is set to 10 ⁻⁴ Pa or less, and after introducing argon gas into the chamber to a gas pressure of 0.6 Pa in this state, a DC voltage of 500 V is further applied to bombard the copper target. Then, the conductor thin film 5 made of copper having a thickness of 300 nm was formed.

  Next, using a third harmonic of a YAG laser (THG-YAG laser) in the atmosphere, the laser is linearly 5 mm on the surface of the conductive thin film 5 with an average output of 6 W, a spot diameter of 40 μm, and a scanning speed of 200 mm / s. Scanned at intervals.

  Thus, after forming the pattern by a laser, the electrolytic copper plating process was performed and the metal conductor layer 3 which consists of a 15-micrometer-thick copper film was formed.

  A peel strength test (90 degree peel test) was performed on the metal conductor layer 3 formed on the mother substrate 4 in this manner. At this time, using a universal material testing machine (manufactured by Shimadzu Corp., “Autograph AG10TD”), the test is performed at a constant speed of 50 mm / s under a room temperature / atmospheric pressure atmosphere, and the unit is based on JIS C6481 The peel strength per width (90 degree peel strength) was calculated.

(Evaluation results)
FIG. 6 shows the measurement results of the reflectance and peel strength for each sample in Example 1 in which the thickness of the coating layer 2 was changed. As shown in the figure, the peel strength increases as the thickness of the coating layer 2 increases, but the degree of increase becomes saturated as the thickness approaches a certain value, and the reflectance increases as the thickness of the coating layer 2 increases. It was something that would drop. Thereby, in order to provide sufficient peel strength and reflectance at the same time, it is determined that the thickness of the coating layer 2 is preferably in the range of 1 to 250 μm.

  Moreover, the measurement results of the surface roughness were all about 0.6 μm regardless of the thickness of the coating layer 2.

[Example 2]
A base material 1 was produced in the same manner as in Example 1 and immersed in sodium hydroxide having a changed concentration to obtain a plurality of mother substrates 4 having different silica concentrations in the coating layer 2.

  The same peel strength measurement as that in Example 1 was performed on the mother substrate 4. The result is shown in FIG.

  As shown in the results, the higher the alumina content in the coating layer 2 is, the higher the peel strength is. To achieve high peel strength, the alumina content in the coating layer 2 is 99% by mass. It is determined that the above is preferable.

Example 3
A base material 1 was produced in the same manner as in Example 1, and the third harmonic of a YAG laser (THG-YAG laser) was used on the surface of the base material 1 in the atmosphere. The average output was 5 W, the spot diameter was 40 μm, At a scanning speed of 200 mm / s, a laser was linearly scanned on the surface of the substrate 1 in parallel at intervals of 5 mm. Thereby, the silica in the laser irradiation location was eluted, and the coating layer 2 was formed.

  Then, the metal conductor layer 3 was formed only at the location where the coating layer 2 was formed by the same method as the above peel strength measurement, and the peel strength of the metal conductor layer 3 was measured and found to be 1.2 N / mm. It was.

  Further, when the reflectance was measured in the same manner as in Example 1, the reflectance was 78%.

Example 4
During firing in Example 1, the furnace temperature was raised from room temperature to 1600 ° C. over 10 hours, and then kept at 1600 ° C. for 1 hour to sinter, followed by further heating rate of 100 ° C. / The temperature was raised to 1700 ° C. over 1 hour and heated, and silica was eluted from the surface layer of the substrate 1 to form the coating layer 2 (see FIG. 8).

  When this mother board 4 was subjected to the same evaluation test as in Example 1, the peel strength was 1.3 N / mm, the reflectance was 73%, and the surface roughness was 0.3 μm.

[Comparative Example 1]
When the peel strength and the reflectance were measured on the base material 1 produced in the same manner as in Example 1 without forming the coating layer 2, the peel strength was 0.2 N / mm and the reflectance was 80%. Met.

  In Comparative Example 1, although the reflectance is high, the peel strength is extremely low and not suitable for practical use. On the other hand, in Examples 1 to 3 described above, both the peel strength and the reflectance are excellent. became.

(A)-(c) is sectional drawing which shows an example of the manufacturing process of the ceramic substrate based on this invention. (A) and (b) are some sectional drawings which show an example of embodiment of this invention. An example of the manufacturing process of the conductor wiring in the ceramic substrate which concerns on this invention is shown, (a) to (c) is the fractured perspective view. (A)-(c) is the fracture | ruptured perspective view which shows the other example of the manufacturing process of the ceramic substrate based on this invention. (A) and (b) are the fractured perspective views which show the process following the process shown in FIG. It is a graph which shows the measurement result of the reflectance and peel strength about the sample which changed the thickness of the coating layer in Example 1. It is a graph which shows the measurement result of the peel strength about the sample which changed the alumina content rate in the coating layer in Example 2. FIG. 6 is a graph showing heating conditions during firing in Example 4.

Explanation of symbols

1 Base material 2 Coating layer 3 Metal conductor layer

Claims (5)

Compared to the base material, the surface of the base material made of a material containing alumina and silica and having a silica content of 2% by mass or more is irradiated with the electromagnetic wave partly. forming a coating layer of alumina content consists high and low content of silica material, the photoelectric conversion element mounting ceramic substrate characterized in that by forming a metal conductive layer on the surface of the coating layer. The manufacturing method of the ceramic substrate for photoelectric conversion element mounting characterized by including the process of the following (a) to (c).
(A) The base material formation process which forms the base material 1 which consists of a material which contains an alumina and a silica and the content rate of a silica is 2 mass% or more.
(B) A material having a higher alumina content and a lower silica content than the base material on the surface of the base material by removing silica in the surface layer of the base material formed by the base material forming step and leaving alumina. The silica removal process which forms the coating layer which consists of.
(C) A metal conductor layer forming step of forming a metal conductor layer on the surface of the coating layer formed by the silica removing step. The method for producing a ceramic substrate for mounting a photoelectric conversion element according to claim 2 , wherein in the silica removal step, silica in the surface layer of the base material is removed by immersing the base material in an alkaline solution. 3. The method for producing a ceramic substrate for mounting a photoelectric conversion element according to claim 2 , wherein, in the silica removal step, silica in the surface layer of the base material is removed by heat-treating the base material at a temperature equal to or higher than the melting point of silica. . 3. The method for producing a ceramic substrate for mounting a photoelectric conversion element according to claim 2 , wherein, in the silica removal step, the surface of the base material is irradiated with electromagnetic waves to remove silica at a portion irradiated with the electromagnetic waves. .

Images