JP2011111365A - Opaque ceramic sintered body and operation panel using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an opaque ceramic sintered body which is an opaque ceramic material made of white alumina, having low total transmittance to visible light and good mechanical characteristics. <P>SOLUTION: The opaque ceramic sintered body 1 is characterized in that: in a portion having a cross-sectional area of 9.074×10<SP>5</SP>μm<SP>2</SP>in an inner portion 1c of the opaque ceramic sintered body 1, the sintered body has porosity of 2.5% or more and 4.5% or less and a number of pores of 7,000 or more and 12,950 or less with respect to pores having a circle-equivalent diameter of 0.8 μm or more, and has a cumulative relative frequency of 70% or more of pores having a circle-equivalent diameter of 1.6 μm or less in the pore distribution; and the total transmittance of the sintered body having a thickness of 0.5 mm or more and 0.8 mm or less at a wavelength of 500 nm is 6.8% or more and 9.2% or less. The opaque ceramic sintered body has low transmittance (sufficient opaqueness) of light at a wavelength in a visible light range, has sufficient adhesion strength to a conductor even when the conductor is printed in a thick film, as well as high mechanical strength, and has inexpensive material cost and production cost. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a translucent ceramic sintered body in which a conductor is directly printed on the back surface. More specifically, the present invention is used as an operation panel in which buttons for operation are arranged on the outer surface of electronic equipment, and on the back surface of the operation panel. Relates to a translucent ceramic sintered body in which a conductor printed with a thick film is formed, and does not impair the adhesion strength of the conductor and has excellent translucency in the visible light region.

  In operation panels such as operation panels and instrument display boards for electronic devices, the background color is often white, and the displayed buttons, scales or pointers are often dark. In these operation panels, in order to design an electronic device more compactly, an electronic circuit is formed by pasting a circuit board on which a conductor is printed on a substrate on the back surface of an operation panel made of metal or resin. Yes. In addition, the number of parts is reduced and the manufacturing cost is reduced.

In Patent Document 1, a colored magnetic composition composed of Al ₂ O ₃ and Nd ₂ O ₃ is within a range of Al ₂ O ₃ 90 to 99.7% and Nd ₂ O ₃ 10 to 0.3% in molar ratio. Thus, it is disclosed that it is effective as a light-shielding magnetism with a high frequency and a low loss because it can be colored in deep blue without specifically deteriorating the high frequency characteristics to reduce the light transmittance.

Patent Document 2 discloses that black sintered quartz containing 0.05 to 1.0% by weight of carbon containing SiO ₂ as a main component and having an aluminum content of 1000 ppm by weight or less and nucleation other than carbon, silicon, and aluminum. By making the total amount of the agent 100 ppm by weight or less, light can be absorbed by a heat treatment process such as infrared heating, and it is possible to obtain black sintered quartz having high thermal efficiency and excellent chemical resistance. It is disclosed.

  Circuit patterns are also printed directly on these ceramics, which are insulators, and black or dark colors are used to improve the concealment of structures such as circuit patterns and wiring that are the background of operation panels. Is generally used.

  FIG. 5 shows an example of a configuration when a conventional light-transmitting ceramic sintered body is used as an operation panel for an electronic device, (a) is a plan view, and (b) is an A- It is sectional drawing in the A 'line.

  An operation panel 102 shown in FIG. 5 includes a sintered body 101 and a conductor 103 printed directly on the back surface thereof. The operation panel 102 is provided with a button 121 having a switch function for electrically turning on and off the conductor 103 formed on the back surface.

  For such an operation panel 102 for electronic equipment, for example, a sintered body 101 made of colored opaque glass as disclosed in Patent Documents 1 and 2 is used. The button 121 is inserted into the through-hole 101d formed in Fig. 5B, and the conductor 103 is electrically turned off by pressing the button 121 from the left side to the right side of the drawing (FIG. 5 (b) shows Electrically on)

  This operation panel 102 is often surrounded by a panel cover (not shown) and is often attached to the most easily visible part of the electronic device. Usually, characters and figures are darkly colored on the surface of the operation panel 102. An operation button 121 is attached to the through hole 101d of the operation panel 102 (sintered body 1). Even if the thickness of the operation panel 102 is thin, the color of the operation panel 102 is black or dark, so that the conductor 103 and other structures on the back surface of the operation panel 102 cannot be seen through from the outside. Since the circuit pattern is directly formed on the back surface of the operation panel 102, the number of parts can be reduced and the electronic device can be made more compact.

  Also, in the field of LEDs (light emitting elements), ceramic materials with increased reflectivity have been actively developed. Particularly, since cost reduction is a major issue, relatively inexpensive aluminum oxide is the main component. High reflective materials are being adopted, and are disclosed in Patent Documents 3 and 4, for example.

  Patent Document 3 describes a highly reflective white ceramic substrate for a semiconductor light emitting device, which is composed of aluminum oxide and a glassy component and has a porosity of 5%, or is composed of aluminum oxide and a glassy component, and is an arithmetic average. The roughness (Ra) is 0.5 μm or less, or it is composed of aluminum oxide and a glassy component. The content of aluminum oxide is 75 to 85% by weight and contains silica, calcium, magnesium and barium as the glassy component. In addition, it is disclosed that the reflectance of light at a wavelength of 450 to 750 nm is set to 90% or more by setting the average crystal grain size of aluminum oxide to 0.5 μm or less.

  In Patent Document 4, the frame surrounding the light-emitting element mounting portion has a thickness of 0.8 mm or more, the alumina content is 90 to 99% by weight, and the total oxide content of silica, calcia and magnesium is 1 to 10% by weight. It is disclosed that the reflectance of light having a wavelength of 400 to 700 nm can be increased to 80% or more, preferably by containing zinc oxide.

  These highly reflective materials disclosed in Patent Documents 3 and 4 contain aluminum oxide as a main component and contain oxides such as silica, calcia, and magnesium, and are relatively inexpensive in terms of both raw materials and manufacturing costs. Therefore, by using these, it can contribute to the cost reduction of the apparatus using LED. In addition, although there is no description regarding translucency, having high reflectivity can be said to be a material with low translucency.

JP-A 62-270460 Japanese Patent Laid-Open No. 2001-180964 JP 2007-284333 A JP 2004-207678 A

  However, although the ceramics disclosed in Patent Documents 1 and 2 are dark blue or black, they have high background concealment when used as an operation panel, but buttons, scales or pointers displayed on the surface of the operation panel Is often unsuitable as an operation panel for a display panel because a black system is often used and there is no color difference between the operation panel and these display bodies and it is difficult to confirm.

  Moreover, when the highly reflective material described in Patent Document 3 is used for an operation panel, light transmittance at a wavelength in the visible light range is considered to be considerably low due to the addition of barium carbonate. Although it has excellent background concealment properties, it has not been able to solve the problem of cost reduction due to the high material cost due to the addition of barium.

In addition, the highly reflective material described in Patent Document 4 has a reflectance of 79.7 to 81.6% at a wavelength of 350 to 750 nm in a ceramic substrate containing Al ₂ O _3, MgO, CaO, ZrO ₂ and SiO ₂ . However, since it contains ZrO ₂ , the light transmitted into the substrate creates scattered light with ZrO ₂ having a different refractive index interposed between the alumina particles, leading to an increase in diffuse reflected light on the surface of the substrate. % Of the reflectance, for example, even if the transmittance at the substrate thickness of 0.635 mm is estimated, it does not become 10% or less. There wasn't. Further, since zirconia having a relatively high material cost is added, the problem of cost reduction cannot be solved.

  As described above, in the operation panels and instrument display boards for electronic devices, there is a ceramic sintered body that is white and opaque and satisfies both mechanical strength, conductor adhesion strength, and low cost. It was sought after.

  The present invention has been devised to solve the above problems, and is a white ceramic sintered body having a small thickness, which can be easily distinguished from buttons, scales or pointers, and is used for operating electronic devices. When used as a panel, the light transmittance at wavelengths in the visible light range is low (exceeding translucency), and even with a switch function and thick film printed directly on the back, sufficient conductor adhesion strength The object of the present invention is to provide a translucent ceramic sintered body having high mechanical strength and low material and manufacturing costs.

The translucent ceramic sintered body of the present invention is a translucent ceramic containing aluminum oxide having a content of 94% by mass to 97% by mass, silicon oxide, and at least one of calcium oxide and magnesium oxide. A sintered body having a cross-sectional area of 9.074 × 10 ⁵ μm ² inside the sintered body, the porosity is 2.5% or more and 4.5% or less when the pores having an equivalent circle diameter of 0.8 μm or more are viewed. Yes, the number of pores is 7000 or more and 12950 or less, the cumulative relative frequency of the equivalent circle diameter of 1.6 μm or less in the pore distribution is 70% or more, and the thickness of the sintered body is 0.5 mm or more and 0.8 mm or less The total transmittance at a wavelength of 500 nm is 6.8% or more and 9.2% or less.

  Moreover, the translucent ceramic sintered body of the present invention is characterized in that, in the above structure, the content of the silicon oxide is 1% by mass or more and 3% by mass or less.

  In addition, the translucent ceramic sintered body of the present invention is characterized in that, in any of the above-described configurations, the average pore diameter in the interior is 1.0 μm or more and 1.95 μm or less.

  Furthermore, the operation panel of the present invention is characterized by using any one of the above-described structurally opaque ceramics.

According to the translucent ceramic sintered body of the present invention, the translucency containing aluminum oxide having a content of 94% by mass to 97% by mass, silicon oxide, and at least one of calcium oxide and magnesium oxide. When the pores with an equivalent circle diameter of 0.8 μm or more are seen in the cross-sectional area of 9.074 × 10 ⁵ μm ² inside the sintered ceramic, the porosity is 2.5% or more and 4.5% The number of pores is 7000 or more and 12950 or less, the cumulative relative frequency of the equivalent circle diameter 1.6 μm or less in the pore distribution is 70% or more, and the thickness of the sintered body is 0.5 mm or more and 0.8 Since the total transmittance at a wavelength of 500 nm at a wavelength of mm or less is 6.8% or more and 9.2% or less, sinterability can be achieved even at a low firing temperature of 1530 ° C or less without using high-cost barium. The mechanical strength of the sintered body The sintered body is also highly resistant and is not easily damaged even when used as an operation panel for an electronic device or an operation panel for a display panel.

  In addition, since silicon oxide is included in the composition of the material, when silicon oxide forms a grain boundary phase, a thick film paste for forming a conductor on the surface of the sintered body is applied and fired thick, Since the conductor enters the grain boundary phase made of silicon oxide, the adhesion strength of the conductor can be increased by the anchor effect, and the conductor serving as the circuit pattern can be formed directly on the back surface of the operation panel.

Furthermore, in the portion of the cross-sectional area of 9.074 × 10 ⁵ μm ² inside the sintered body, the porosity is 2.5% or more and 4.5% or less when the pores with an equivalent circle diameter of 0.8 μm or more are seen, and the number of pores is Since the cumulative relative frequency of 7000 to 12950 and the equivalent circular diameter of 1.6 μm or less in the pore distribution was 70% or more, the number of pores was increased without increasing the porosity. By bringing the peak of the number of pores to a circle equivalent diameter of 1.6 μm or less in the distribution, it becomes possible to widen the area of the interface between the grain boundary phase and the pores, and the surface of the sintered body over the entire visible light region. The light transmitted through the alumina particles can be diffused and reflected at the interface, and when the thickness of the sintered body is 0.5 mm or more and 0.8 mm or less, the total transmittance at a wavelength of 500 nm to the back surface is 6.8% or more and 9.2% or less. From the back of the sintered body The background of conductors or wiring is not seen through, and when used as an operation panel, the background can be concealed.

  Moreover, according to the opaque ceramic sintered body of the present invention, when the content of silicon oxide is 1% by mass or more and 3% by mass or less, the grain boundary phase composed of a glass phase together with the grain boundary phase composed of silicon oxide. Since it can be sufficiently sintered even at a low temperature, the mechanical strength can be ensured and the adhesion strength of the thick film to the opaque ceramic sintered body can be increased. The effect by the grain boundary phase can be obtained more effectively.

  Furthermore, according to the light-transmitting ceramic sintered body of the present invention, when the average pore diameter in the interior is 1.0 μm or more and 1.95 μm or less, light having a wavelength close to the ultraviolet region is particularly inside the sintered body. Since the effect of suppressing the transmittance to the back surface can be obtained by diffusing and reflecting at the interface between the alumina particles and the pores of the ceramic, the transmittance of the light transmitted to the back surface of the sintered body can be reduced. Can do.

  Therefore, if such an opaque ceramic is used as an operation panel, the mechanical strength and the adhesion strength of the conductor are high, the background is well concealed, and the cost can be reduced.

An example of a structure when the opaque ceramic sintered body of the present invention is used as an operation panel for an electronic device is shown, (a) is a plan view, and (b) and (c) are in (a). It is sectional drawing in the AA 'line. It is sectional drawing which shows the state of the crystal | crystallization inside the translucent ceramic sintered compact of this invention. It is a conceptual diagram which shows the state which the incident light to the surface of the translucent ceramic sintered compact of this invention permeate | transmits and scatters. It is sectional drawing which shows the measuring method of the adhesive strength with respect to the conductor adhere | attached on the surface of the translucent ceramic sintered compact of this invention. An example of the structure when the conventional opaque ceramic sintered body is used as an operation panel for an electronic device is shown, (a) is a plan view, and (b) is an AA ′ line in (a). FIG.

  Hereinafter, the example of embodiment of the translucent ceramic sintered compact of this invention is demonstrated.

  FIG. 1 shows an example of a configuration when the translucent ceramic sintered body of the present invention is used as an operation panel for electronic equipment, (a) is a plan view, and (b) and (c) are ( It is sectional drawing in the AA 'line in a).

  The operation panel 2 using the opaque ceramic sintered body 1 (hereinafter simply referred to as the sintered body 1) shown in FIG. 1 is surrounded by a panel cover (not shown) and is most easily visible such as an electronic device. The buttons, scales, or pointers are usually displayed in a dark color (not shown) on the surface 1a of the operation panel 2, and the operation panel 2 has a through hole 1d for operation. The button 21 is attached. Here, as an example, the button 21 is made of conductive rubber and integrated with the switch 23. The conductor 3 is directly formed on the back surface 1b of the operation panel 2 by thick film printing or the like, and in the case of the switch function as illustrated, the conductor 3 is formed on both sides of the through hole 1d. For example, in FIG. When the button 21 is pressed by the switch 23, as shown in FIG. 1C, the switch 23 made of conductive rubber is separated from the conductors 3 on both sides of the through hole 1d and is turned off. On the surface 1a of the operation panel 2, the surface of the sintered body 1 is exposed at portions other than the necessary display such as the button 21 attached to the through hole 1d, the scale or the pointer. Further, the conductor 3 is directly formed on the back surface 1b, and an electronic component or the like may be mounted.

  Note that the structure of the switch 23 including the button 21 described here does not constitute the configuration of the present invention, but is merely an example for explaining the invention.

The composition of the translucent ceramic sintered body 1 of the present invention has an aluminum oxide content of 94% by mass to 97% by mass, silicon oxide, and at least one of calcium oxide and magnesium oxide. Yes. Further, in the portion of the cross-sectional area of 9.074 × 10 ⁵ μm ² in the interior 1c of the opaque ceramic sintered body 1, the porosity in the pore distribution having an equivalent circle diameter of 0.8 μm or more is in the range of 2.5% to 4.5%. Yes, the number of pores is in the range of 7000 to 12950, the cumulative relative frequency of the equivalent circle diameter of 1.6 μm or less in the pore distribution is 70% or more, and the thickness of the sintered body 1 is 0.5 mm or more At 0.8 mm or less, the total transmittance at a wavelength of 500 nm needs to be 6.8% or more and 9.2% or less.

  FIG. 2 is a cross-sectional view showing the state of crystals inside the translucent ceramic sintered body of the present invention.

  The inside of the sintered body 1 shown in FIG. 2 basically includes alumina particles 4, a glass phase (grain boundary phase) 5 made of silicon oxide or the like, pores 6, and a glass phase 5 of alumina particles 4. And an interface 7.

  FIG. 3 is a conceptual diagram showing a state in which incident light to the surface of the translucent ceramic sintered body of the present invention is transmitted and scattered.

  In the conceptual diagram showing a state in which the incident light 11 to the surface 1a of the sintered body 1 shown in FIG. 3 is transmitted and scattered, a part of the incident light 11 to the surface 1a is the surface 1a and is opposite to the angle of the incident light 11 It becomes specularly reflected light 13a reflected at the same angle in the direction, and part thereof becomes diffusely reflected light 13d reflected in all directions by the surface 1a. The remainder becomes the transmitted light 12 that passes through the alumina particles 4 or the pores 6 and the glass phase (grain boundary phase) 5. The transmitted light 12 is refracted by the linearly transmitted light 12b that is transmitted to the back surface 1b along the extension line of the incident light 11 and is emitted to the front surface, the alumina particles 4, the pores 6, the glass phase (grain boundary phase) 5, and the like. At the interface 7 between the particles 4 and the glass phase 5, the diffuse reflected light 13 b and the diffuse transmitted light 12 c are formed, and a part of the diffuse transmitted light 12 c is emitted from the back surface 1 b of the sintered body 1. Further, the transmitted light 12 becomes diffuse reflected light 13c and diffuse transmitted light 12c also at the interface 8 between the pores 6 and the glass phase 5, and the total of these diffuse transmitted light 12c and linear transmitted light 12b is the total transmitted light 12a. And released from the back surface 1b of the sintered body 1. The ratio of the total transmitted light 12a at the thickness t of the sintered body 1 to the incident light 11 is the light transmittance.

  The ceramics sintered body 1 for mounting a light-emitting element of the present invention has a content of aluminum oxide as a main component in the range of 94% by mass or more and 97% by mass or less. Therefore, silicon oxide excluding inevitable impurities and calcium oxide And the total content of at least one of magnesium oxide is 3% by mass or more and 6% by mass or less of the balance, so that it does not use barium or zirconium, which are high in material cost, and is about 40% higher than the normal firing temperature. Even if it is fired at a temperature of 1530 ° C. or lower, which is as low as ˜120 ° C., the sinterability is sufficiently enhanced, and therefore the cost of the ceramic sintered body can be reduced.

  In addition, it can satisfy the mechanical properties such as bending strength and hardness required for an electronic component substrate as a base for an operation panel of an electronic device or a display panel, and silicon oxide forms a grain boundary phase (glass phase) 5. When the thick film paste for forming the conductor 3 is applied to the back surface 1b of the sintered body 1 and the thick film is fired, the conductor enters the grain boundary phase 5 made of silicon oxide. The adhesion strength can be increased.

Furthermore, in the portion of the cross-sectional area of 9.074 × 10 ⁵ μm ² in the interior 1c of the sintered body 1, the porosity is 2.5% or more and 4.5% or less when the pores having an equivalent circle diameter of 0.8 μm or more are seen. Wavelength when the number is 7000 or more and 12950 or less, the cumulative relative frequency of the equivalent circle diameter 1.6 μm or less in the pore distribution is 70% or more, and the thickness t of the sintered body 1 is 0.5 mm or more and 0.8 mm or less Since the total transmittance at 500 nm was assumed to be 6.8% or more and 9.2% or less, the number of pores was increased without increasing the porosity, so that the peak of the number of pores appeared at an equivalent circle diameter of 1.6 μm or less in the pore size distribution. Can bring. As a result, since the area of the interface 8 between the grain boundary phase 5 and the pores 6 can be increased, the light (transmitted light 12) transmitted through the grain boundary phase 5 and the alumina particles 4 inside the sintered body 1a. It can also be diffused at the interfaces 7 and 8 between the grain boundary phase 5 and the alumina particles 4 or the pores 6 and reflected as diffuse reflected light 13b and 13c. As a result, the total transmitted light emitted to the back surface 1b of the sintered body 1 12a (linearly transmitted light 12b, diffused transmitted light 12c) is significantly reduced. In other words, relatively inexpensive aluminum oxide and silicon oxide can be used without using an expensive material such as barium as a scattering material for increasing the light reflectance as in the prior art (or for enhancing the light shielding effect). The total transmittance at an intermediate wavelength of 500 nm in the visible light region is 9.2% or less even in the white sintered body 1 having a thickness t of 0.50 mm, for example, by containing at least one of calcium oxide and magnesium oxide. can do.

Here, the inside 1c of the sintered body 1 refers to any portion between the front surface 1a and the thickness t of the back surface 1b of the sintered body 1, and a portion having a cross-sectional area of 9.074 × 10 ⁵ μm ^{2 in} the inside 1c. The number of pores in the pores 6 is 9000 or more and 12950 or less where both the mechanical properties and the reflectance are the best, and the cumulative relative frequency of the circle equivalent diameter 1.6 μm or less in the pore distribution with the circle equivalent diameter 0.8 μm or more Is more preferably 75% or more, the sintering temperature is set to about 1450 to 1530 ° C., and the temperature variation in the firing furnace is suppressed so that the sintered body is sintered more uniformly, and the number of formed bodies can be stacked. Such a sintered body 1 can be obtained by reducing the temperature and performing strict control of the temperature profile of temperature increase or decrease.

  Further, when the opaque ceramic sintered body 1 of the present invention is used as an operation panel for an electronic device or an operation panel 2 for a display panel, the thickness t of the sintered body 1 is in a range of 0.5 mm to 0.8 mm. When the conductor 3 is formed on the back surface 1b, the operation buttons and scales or pointers are displayed on the front surface 1a, and the through hole 1d is formed and the operation button 21 is provided in the through hole 1d, For example, even if it is used as an operation plate, there is no risk of damage in normal use, the adhesion strength of the conductor 3 is high, and the background including the conductor 3 formed on the back surface 1b is not under back lighting. Good concealment can be ensured without fear of being seen through the surface 1a under room illumination (under three-wave daylight illumination with an illuminance of about 300 lx).

For the measurement of the average pore diameter, the number of pores, the porosity and the pore distribution of the pores 6, the surface 1a of the sample of the sintered body 1 is mirror-polished to a depth of, for example, 10 μm, and the magnification is 100 times. A microscope image is taken into a CCD camera and analyzed using an image analyzer to digitize it. Specifically, the model name Win ROOF made by Mitani Corporation is used for the image analysis software, and each measured value with a circle equivalent diameter of 0.8 μm as a threshold value for a cross-sectional area of 9.074 × 10 ⁵ μm ² May be calculated.

  The light transmittance is measured using a spectrophotometer (for example, a spectrophotometer model name UV-315 manufactured by Shimadzu Corporation and an integrating sphere unit model name ISR-3100), and a 50 W halogen lamp as a light source. And a deuterium lamp, the wavelength range was 200 to 1000 nm, the measurement range was diffuse reflectance (7 × 9 mm at 20 nm slit), and no mask was used, and measurement was performed using barium sulfate powder as a reference. .

  Moreover, it is preferable that the translucent ceramic sintered compact 1 of this invention is 1 mass% or more and 3 mass% or less of silicon oxide content.

  If the content of silicon oxide is 1% by mass or more and 3% by mass or less, the glass phase 5 can be sufficiently formed so as to surround the alumina particles 4 as shown in FIG. Further, since the sintering is sufficiently performed even at a low temperature such that the firing temperature is lower than 1530 ° C., the mechanical strength can be ensured.

  When the sintered body 1 is used as an operation panel 2 of an electronic device or a display panel, a conductor 3 serving as a circuit pattern is formed on the back surface 1b. The conductor 3 is thickened by applying a thick film paste. In the case of forming the film by baking, the printed conductor 3 is firmly adhered by the paste containing the metal entering the surface layer from the surface of the sintered body 1 and being baked. At this time, if the content of silicon oxide is less than 1% by mass, a sufficient glass phase (grain boundary phase) 5 is not formed around the alumina particles 4, and therefore the biting of the conductor 3 is reduced. The adhesion strength will be reduced.

  Moreover, when content of silicon oxide exceeds 3 mass%, mechanical strength (bending strength) will fall or hardness will fall. Furthermore, abnormal crystals such as mullite may be crystallized, and these crystallized substances may cause a decrease in electrical characteristics, which may cause a problem as an electronic component substrate.

  Furthermore, the translucent ceramic sintered body 1 of the present invention preferably has an average pore diameter in the interior 1c of 1.0 μm or more and 1.95 μm or less.

  As shown in FIG. 3, when incident light 11 is incident on the surface 1 a of the sintered body 1, specularly reflected light 13 a that is partially reflected on the surface 1 a at the same angle in the opposite direction to the angle of the incident light 11; Moreover, it becomes the diffusely reflected light 13d reflected in all directions on the surface 1a and is reflected to the outside, and the remaining light is transmitted through the alumina particles 4 or the pores 6 and the glass phase (grain boundary phase) 5. Light 12 The transmitted light 12 passes along the extended line of the incident light 11 to the back surface 1b of the sintered body 1 having a thickness t and is emitted to the front surface, and the linearly transmitted light 12b, alumina particles 4, pores 6, and glass phases (grain boundaries). Phase) 5 and the like, while being refracted at 5 or the like, diffused reflected light 13b and diffused transmitted light 12c are formed at the interface 7 between the alumina particles 4 and the glass phase 5, and a part of the diffused transmitted light 12c comes from the back surface 1b of the sintered body 1. Released. Further, the transmitted light 12 becomes diffuse reflected light 13c and diffuse transmitted light 12c also at the interface 8 between the pores 6 and the glass phase 5, and the total of these diffuse transmitted light 12c and linear transmitted light 12b is the total transmitted light 12a. And released from the back surface 1b of the sintered body 1. The ratio of the total transmitted light 12a to the incident light 11 to the sintered body 1 having the above thickness t is the light transmittance.

  Here, according to the translucent ceramic sintered body 1 of the present invention, the diffuse reflected light 13c similar to the interface 7 between the alumina particles 4 and the glass phase 5 is generated even at the interface 8 between the pores 6 and the glass phase 5. By doing so, since the total transmitted light 12a including the diffused transmitted light 12c to the back surface 1b of the sintered body 1 is remarkably reduced, it is considered that the opaqueness is improved.

  Moreover, it is preferable that the translucent ceramic sintered body 1 of this invention is 1.0 micrometer or more and 1.95 micrometers or less in the average pore diameter inside.

  Further, if the average pore diameter of the pores 6 is in the range of 1.0 μm or more and 1.95 μm or less, the diffuse reflected light 13b and the diffuse reflected light 13c inside the sintered body 1 are preferably generated. It is considered that the transmitted light 12b and the diffused transmitted light 12c are reduced, and the total transmitted light 12a to the back surface 1b in which these are added is remarkably reduced.

  Next, an example of the manufacturing method of the translucent ceramic sintered compact of this invention is demonstrated.

First, aluminum oxide (Al ₂ O ₃ ) powder having an average particle diameter of about 1.4 to 1.8 μm, silicon oxide (SiO ₂ ), calcium oxide (CaO), and magnesium oxide for manufacturing the sintered body 1. (MgO) at least one kind of powder was prepared, and the mixed powder weighed so that the total content of each powder would be 100% by mass was put into a rotary mill together with a solvent such as water to obtain a high purity alumina ball Use to mix. Next, a molding binder such as polyvinyl alcohol, polyethylene glycol, acrylic resin, or butyral resin is added to this in an amount of about 4 to 8% by mass with respect to 100% by mass of the mixed powder, and mixed to obtain a slurry. Next, this slurry is used to form a ceramic sheet by the doctor blade method, roll compaction molding method or extrusion molding method. Next, a raw molded body is produced by a mold for forming a product shape or laser processing. To do. Here, the sintered body 1 on which the light-emitting element is finally mounted may be a single product, but in view of mass productivity, a multi-piece molded body is more preferable. Finally, the obtained molded body is set to a maximum temperature of about 1450-1530 ° C using a firing furnace (for example, a pusher type tunnel kiln, a roller type tunnel kiln or a batch furnace) in an oxidizing atmosphere. The sintered body 1 of the present invention can be manufactured by firing.

  Next, an example of the manufacturing method of the operation panel of this invention is demonstrated.

  As shown in FIG. 1, in the operation panel of the present invention, a thick film paste (not shown) is first applied to the through hole 1d and the back surface 1b of the sintered body 1, and then fired at a temperature of about 850 ° C. By doing so, the conductor 3 is formed. Next, a switch 22 made of conductive rubber having buttons 21, such as numbers, letters, or figures formed on the surface is prepared, and is slightly spaced above the two through holes 1d of the sintered body 1 to obtain a desired method. Install by. Although this attachment method is not shown, for example, both ends of the button 21 may be bonded and fixed to the surface 1a of the operation panel 2 with an insulating adhesive.

  In FIG. 1B, when the button 21 is not pressed, the switch 23 is short-circuited with the conductor 3 and is electrically on. However, in FIG. In this structure, the conductor 3 on the 1b side and the switch 23 are separated from each other to be electrically turned off.

  When the sintered body 1 of the present invention is used for such an application, even if it is a white ceramic substrate having a relatively thin thickness (thickness of 0.5 mm or more and 0.8 mm or less), the mechanical strength (bending strength) is high. The operation panel 2 is less likely to be damaged even if the button 21 or the like is pressed as the operation panel 2, and the conductor 3 formed on the back surface 1b is not seen through from the front side. Since the number of parts used can be reduced, the background can be concealed, the adhesion strength of the conductor 3 is high, and the cost can be reduced.

  Examples of the opaque ceramic sintered body of the present invention will be described below.

  First, an example of the manufacturing method of the translucent ceramic sintered compact of this invention is demonstrated.

As aluminum oxide (Al ₂ O ₃ ), a powder having an average particle diameter of about 1.6 μm, silicon oxide (SiO ₂ ), and at least one powder of calcium oxide (CaO) and magnesium oxide (MgO) are prepared. Then, the mixed powder weighed so that the total content of each powder is 100% by mass is put into a rotary mill together with a solvent such as water and mixed with high-purity alumina balls.

  Next, a molding binder such as an acrylic resin is added thereto and mixed to obtain a slurry. Here, the addition amount of the molding binder is about 4 to 8% by mass with respect to 100% by mass of the mixed powder. Within this range, there is no problem in the strength and flexibility of the molded article, and there is no problem due to insufficient degreasing of the molding binder during firing.

  Next, a slurry obtained by mixing the mixed powder and the molding binder is formed into a sheet shape by a known doctor blade method, and the sheet is processed into a product shape dimension by a mold. The sheet molding method may be a known roll compaction molding method or extrusion molding method, and the processing of the obtained sheet into a product shape may be a laser processing method or the like.

Next, in order to sinter the molded product having this product shape, firing was performed in a pusher-type tunnel kiln under the temperature conditions shown in Table 1, and sample Nos. As shown in Table 1 were obtained. Samples of 1 to 23 opaque translucent ceramics were obtained (the thicknesses of the sintered bodies were 30 each of 0.45 mm, 0.50 mm, 0.60 mm, 0.80 mm, and 0.85 mm). )
With respect to the obtained sample of the translucent ceramic sintered body, the porosity, the number of pores, the cumulative relative frequency of the pore distribution, the bending strength, the adhesion strength of the conductor and the transmittance were measured by the following methods.

The measurement of cumulative relative frequency (hereinafter referred to as cumulative relative frequency) of the equivalent circle diameter of 1.6 μm or less in the porosity, the number of pores and the pore distribution of the opaque ceramic sintered body 1 is 10 μm from the surface of each sample. The surface was mirror-polished to a depth, and a metal microscope image with a magnification of 100 was captured by a CCD camera and digitized using an image analyzer. Specifically, the microscope model name VHX-500 manufactured by Keyence Co., Ltd. was used for the metal microscope, and the digital camera model name DS-2Mv manufactured by Nikon Co., Ltd. was used for the CCD camera. For the cross section of 9.074 × 10 ⁵ μm ² , each measured value was calculated using a circle equivalent diameter of 0.8 μm as a threshold value, using a model name Win ROOF manufactured by Mitani Corporation. The number of measurements is one for each sample, the measurement area per measurement is 2.2685 × 10 ⁵ μm ² , and the total measurement area is 9.074 × 10 ⁵ μm ² with respect to the cross-sectional area of 9.074 × 10 ⁵ μm ² Each data was determined.

  In addition, a sintered body having a length of 30 mm, a width of 10 mm and a thickness of 0.8 mm was manufactured in advance in accordance with JIS R 1601: 2008 under the same composition and the same firing conditions as each sample, and the span of the sintered body was Is applied to a central portion of 20 mm, a load of 0.5 mm / min is applied, the maximum load until the sintered body breaks is measured, and a three-point bending strength is calculated (not shown). The number of measurements was measured for 10 samples, and the average value was obtained.

  Next, FIG. 4 is a cross-sectional view showing a method for measuring the adhesion strength to a conductor deposited on the surface of the translucent ceramic sintered body of the present invention.

  In the method for measuring the adhesion strength shown in FIG. 4, a thick film paste (not shown) is printed on the surface 1a of the sintered body 1 which is the object to be measured, and the size after baking is 2 mm square and the thickness is 10 μm. Conductors 3, 33 made of palladium (model number TR4846, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) were formed and fired at about 850 ° C. Next, on the surfaces of the conductors 3 and 33, a solder 34 having a Sn—Pb (6: 4 solder) system in which Ag is 2% by mass with respect to the whole is used. This is a mixture of a solvent. Soldering a plated lead wire (Sn plating on copper wire) 35 of φ0.6mm at a temperature of 225 ± 5 ° C using the product name XA-100 (manufactured by Tamura Kaken Co., Ltd.) A sample for measurement was prepared. Next, the plated conducting wire 35 was pulled at a rate of 7.62 mm / min, and the strength when the conductors 3 and 33 were peeled off from the sintered body 1 was measured to obtain the adhesion strength of the conductor to the sintered body. This test apparatus used a die sharing tester (model number 520D manufactured by ANZA TECH). The number of measurements was measured for 10 samples, and the average value was obtained. In addition, when the plated copper wire 35 peeled from the conductors 3 and 33, it excluded from data, and the data only when the conductor 33 peeled from the sintered compact 1 was made into the adhesion strength of the conductors 3 and 33. FIG. In addition, the adhesion strength at this time measured the sample whose thickness t is 0.8 mm.

  Next, the transmittance is measured using a spectrophotometer manufactured by Shimadzu Corp. Model name: UV-315 and integrating sphere unit model name ISR-3100, with a 50 W halogen light source. Using a lamp and a deuterium lamp, the wavelength range is 200 to 1000 nm, the measurement range is diffuse reflectance (7 x 9 mm at 20 nm slit), no filter or mask is used, and barium sulfate powder is used as the standard for reflectance It measured using. In addition, the number of measurement samples was measured at one arbitrary place for each of the sintered bodies 1 having a thickness of 0.45 mm, 0.50 mm, 0.60 mm, 0.80 mm, and 0.85 mm.

  Next, the background concealment of the operation panel was evaluated (hereinafter not shown). The operation panels 2 and 102 have the same thicknesses of 0.45 mm, 0.50 mm, 0.60 mm, 0.80 mm, and 0.85 mm, and 50 mm square outer diameters are prepared. A circuit board with the same circuit pattern as when the strength was measured was manufactured. And each sample was attached to the front of the box which used the side, the upper and lower surfaces, and the back surface as the light shielding surface. The front surface to which the operation panel is attached is also a light shielding surface. Then, a commercially available fluorescent lamp (Neoball Z 3-wavelength daylight color manufactured by Toshiba Corporation) is used as illumination from above, and the illuminance in the vicinity of the sintered body 1,101 that becomes the operation panel 2,102 as a sample is 300 lx. The lighting was adjusted as follows. Whether the conductor formed on the back surface of the sintered body 1,101 is visible through a visual distance (binocular vision is about 1.0) from a distance of about 3m in the horizontal direction from the position where the sample is attached. I confirmed. The number of samples was one for each.

  Sample No. 2-1 to 19-2 are examples of the opaque ceramic sintered body of the present invention. 1-1, 1-2 and 20-1-23 are outside the scope of the present invention.

  The overall evaluation of each sample is that the bending strength is 320 MPa or more, the adhesion strength of the conductor 3 (33) is 19 MPa or more, and the total transmittance at a wavelength of 500 nm is 9.2% or less. And the thing which was not able to confirm the outline of a background (conductor) was set as the pass (circle), and the thing which was able to confirm was evaluated as unsatisfactory x. Since this evaluation relies on delicate judgments, the number of evaluators is limited to one person, and the sample number is determined three times for each sample in a random order. The background hiding property of the operation panel 1,102 was evaluated.

  And all the evaluations are acceptable, and further, those that satisfy all of the requirements including cost reduction are evaluated as “good” as “good”, and those that do not satisfy any one or more items as “bad” as “bad”. .

  However, since the sample with a thickness t of 0.45 mm of the sintered body 1,101 was the result of the present invention, many samples outside the scope of the present invention had a total transmittance exceeding 9.2% at a wavelength of 500 nm. The evaluation of the hiding property of the background of the operation panel was rejected and excluded from the description in the comprehensive evaluation.

  Further, in the sample with the sintered body 1,101 having a thickness t of 0.80 mm, the total transmittance of all the samples outside the range of the examples of the present invention and the present invention is 9.2% or less, and partly 6.2% Although it is excellent, it has excellent concealment of the background of the operation panel, but in the raw sheet molding, it is necessary to lengthen the drying time if it is a doctor blade method or extrusion molding method, and roll compaction molding method If so, it was necessary to slow down the molding speed. In addition, when the thickness exceeds 0.8 mm, such as by increasing the firing time in firing, the manufacturing cost suddenly increased compared to the improvement rate of the decrease in total transmittance. This was excluded from the description in the comprehensive evaluation in Table 2.

  The obtained results are shown in Tables 1 and 2.

  As can be seen from the results shown in Tables 1 and 2, first, sample No. Since 1-1 and 1-2 have a low aluminum oxide content of 93.5% by mass and a large total content of silicon oxide as the second component and at least one of calcium oxide and magnesium oxide, The bending strength was less than 320 MPa at either 1530 ° C. or 1450 ° C., and the overall evaluation was unacceptable. From this, it can be seen that since the content of aluminum oxide is small and the total content of the second component is too large, the bending strength is lower than that of other samples.

  Sample No. outside the scope of the present invention. 20-1 and 20-2 have a high aluminum oxide content of 97.5% by mass, and the total content of the second component silicon oxide and at least one of calcium oxide and magnesium oxide is low. At either 1530 ° C. or 1450 ° C., the adhesion strength of the conductor was less than 19 MPa, and the overall evaluation failed. This is because the content of silicon oxide is small, but it is considered that the bending strength decreases when the content of the other second component is small. Incidentally, the number of pores was as large as 12,500 and 13500, and the transmittance was less than 9.2% at any thickness, and the concealability of the operation panel was good. This is because the increase in the number of pores increases the generation of diffuse reflected light at the interface between the pores and the glass phase, resulting in a decrease in linear and diffuse transmitted light, resulting in a low total transmittance. It is possible that

  Next, sample No. In 21-1 and 21-2, the content of aluminum oxide is 96.0% by mass, and the other second component is only silicon oxide and does not contain calcium oxide and magnesium oxide. However, at 1530 ° C or 1450 ° C, the number of pores was 5480,5690, the porosity was as low as 2.2, 2.3%, and the cumulative relative frequency was as low as 67.5, 68.0%. This is because neither calcium oxide nor magnesium oxide, which suppresses grain growth, was added, and as the grain growth progressed, pores gathered, resulting in the generation of abnormal pore diameters with a cumulative relative frequency of less than 70%. As a result, the bending strength was slightly low, and as a result, the bending strength was less than 320 MPa, and the overall evaluation was unacceptable.

  Next, a sample No. out of the scope of the present invention. 22 is the average content of aluminum oxide and second component, only the firing temperature is as high as 1550 ° C, but the number of pores is 4570, the porosity is as low as 2.2%, and it is cumulative The relative frequency was as low as 67.0%. This is because the phenomenon that bubbles are released due to the high firing temperature, the porosity and the number of pores are reduced, and the generation of diffuse reflected light at the interface between the pores and the glass phase is reduced, so that linear transmitted light and diffuse transmitted light are reduced. In particular, the total transmittance at a wavelength of 500 nm with thicknesses of 0.50 and 0.60 mm exceeded 9.2%, the background of the operation panel was poorly concealed, and the overall evaluation was unacceptable. Therefore, the standard ceramic substrate for electronic parts containing 96% by mass of the most common aluminum oxide and containing silicon oxide, calcium oxide and magnesium oxide as the second component has a firing temperature of 1580 to 1600 ° C. Therefore, sample no. It can be estimated that the total transmittance is higher than 22.

  Next, a sample No. out of the scope of the present invention. No. 23 is the average content of aluminum oxide and the second component, and only the firing temperature is as low as 1400 ° C, but the number of pores is as high as 13500 and the porosity is as high as 4.5%. The cumulative relative frequency with a pore diameter of 1.6 μm or less was also high at 78.1%. The wavelength of 500 nm is that the firing temperature is high, and the phenomenon that bubbles escape is progressed, the porosity and the number of pores are reduced, and the generation of diffuse reflected light at the interface between the pores and the glass phase is small. Diffuse transmitted light is reduced, and the total transmittance at 500 nm, especially when the thickness is 0.50 or 0.60 mm, is 9.2% or less at all thicknesses, and the background of the operation panel is well concealed, but the bending strength is 320 MPa. The overall evaluation was rejected. Therefore, if the firing temperature is too low, the light-transmitting property is improved, but the sinterability of aluminum oxide is insufficient, so that the mechanical strength is considered to be lowered.

  From the above results, the sample No. 1-1, 1-2 and 20-1 to 21-2, 22 and 23 are one or more of the items of bending strength, adhesion strength and total transmittance of the conductor 33, and background concealment of the operation panel 102. The overall evaluation was rejected because the item was not satisfied.

  In contrast, the sample No. of the example of the present invention. 2-1 to 19-2 can make the total transmittance of light having a wavelength of 500 nm within the range of 6.8 to 9.2% when the thickness t of the sintered body 1 is 0.50 to 0.80 mm. When used as the operation panel 2, the concealability of the back surface of the sintered body 1 under normal illumination was also a good result and passed.

  Further, the bending strength was 320 MPa or more and the adhesion strength of the conductor 3 was 19 MPa or more. In addition, since it is within this thickness range and the firing temperature is 1530 ° C. or lower, the conventional substrate for electronic parts having an alumina content of 96% by mass and other methods for improving the reflectance (light-shielding property) Compared with the case where the above component was added, the manufacturing cost or material cost was significantly reduced, and the overall evaluation was acceptable.

Among these, sample no. 2-1 to 11-2, 15-1 to 16-2, and 17-2 have 9000 pores with an equivalent circle diameter of 0.8 μm or more in the cross-sectional area of 9.074 × 10 ⁵ μm ^{2 in} the interior 1c. In particular, the total transmittance at a wavelength of 500 nm is all 9% or less in the range where the thickness t of the sintered body 1 is 0.50 mm or more and 0.80 mm or less, regardless of whether the firing temperature is 1530 ° C. or 1450 ° C. It was a good result. From this, it can be seen that a more preferable range of the number of pores having an equivalent circle diameter of 0.8 μm or more is 9000 or more and 12950 or less.

  Further, in the present invention, it is essential that at least one of calcium oxide and magnesium oxide is contained, but silicon oxide has sinterability, adhesion strength of a conductor by thick film printing, and reflectance. It is understood that all are essential components for satisfying, and a particularly preferable range is 1% by mass or more and 3% by mass or less.

  Next, the average pore diameter of the sintered bodies 1,101 and the opaqueness (total transmittance) in the near ultraviolet region having a wavelength of 250 to 350 nm were confirmed.

  Sample No. manufactured in Example 1 is outside the scope of the present invention. 21-1 and 23, and sample No. For any of the samples 11-1, 15-2 and 19-1, a sample having a thickness of 0.5 mm was measured for the average pore diameter and the total transmittance at wavelengths of 250 nm and 350 nm by the measurement method of Example 1.

  The obtained results are shown in Table 3.

  As can be seen from the results in Table 3, the sample pores outside the scope of the present invention having an average pore diameter as large as 2.02 μm. 21-1 had a total transmittance of 6.2% at a wavelength of 350 nm and 5.5% at a wavelength of 250 nm. In addition, Sample No. with an average pore size as small as 0.95 μm. In the case of 23, the total transmittance at a wavelength of 350 nm is 5.4% and is 5.2% at a wavelength of 250 nm.

  In contrast, the sample No. of the example of the present invention. 11-1, 15-2 and 19-1 have an average pore diameter in the range of 1.00 to 1.95 μm, the total transmittance at a wavelength of 350 nm is 6.0% or less, and 5.0% or less at a wavelength of 250 nm. It is lower than the outside. From this, it can be seen that the non-translucency is particularly excellent in a region close to ultraviolet rays.

  Further, although the effect of the average pore diameter in this result is not known, it can be seen that if the average pore diameter is in the range of 1.00 μm or more and 1.95 μm or less, it contributes to the improvement of the translucency in the near ultraviolet region.

  As described above, the translucent ceramic sintered body according to the present invention can improve the sinterability even at a low firing temperature of 1530 ° C. or less without using barium or zirconium with high material costs. Therefore, the cost of the ceramic sintered body can be reduced, the bending strength is high, and even if the electrode is directly printed on the ceramic sintered body with a thick film, the conductor has sufficient adhesive strength, and the sintered body Even if the thickness of the ceramic is small, the transmittance is low in a wide range of wavelengths over the entire visible light region, and ceramic firing suitable for mounting a light-emitting element that can sufficiently satisfy both the opaqueness and the mechanical characteristics is possible. It turns out that a ligation is obtained. As its application, in addition to operation panels such as operation panels and display panels of electronic devices, a dummy wafer used in a semiconductor manufacturing apparatus, a CCD camera for an endoscope, and a housing for storing a light source for LED illumination It can also be used for things like

1: Translucent ceramic sintered body (sintered body)
1a: Front surface, 1b: Back surface, 1c: Inside, 1d: Through hole 2: Operation panel 3: Conductor 4: Alumina particles 5: Glass phase (grain boundary phase)
6: Pore 7: Interface (interface between alumina particles and glass phase)
8: Interface (interface between pores and glass phase)
11: Incident light
12: Transmitted light
12a: Total transmitted light, 12b: Linear transmitted light, 12c: Diffuse transmitted light
13: Reflected light
13a: Regular reflection light, 13b: Diffuse reflection light, 13c: Diffuse reflection light, 13d: Diffuse reflection light
21: Button
23: Switch

Claims (4)

A translucent ceramic sintered body containing aluminum oxide having a content of 94% by mass or more and 97% by mass or less, silicon oxide, and at least one of calcium oxide and magnesium oxide, In the portion of the cross-sectional area of 9.074 × 10 ⁵ μm ² , when the pores having an equivalent circle diameter of 0.8 μm or more are viewed, the porosity is 2.5% or more and 4.5% or less, and the number of pores is 7000. The wavelength is 500 nm when the cumulative relative frequency of the circle equivalent diameter of 1.6 μm or less in the pore distribution is 70% or more and the thickness of the sintered body is 0.5 mm or more and 0.8 mm or less. The translucent ceramic sintered body characterized by having a total transmittance of 6.8% or more and 9.2% or less.   2. The opaque ceramic sintered body according to claim 1, wherein a content of the silicon oxide is 1% by mass or more and 3% by mass or less.   3. The translucent ceramic sintered body according to claim 1, wherein an average pore diameter in the interior is 1.0 μm or more and 1.95 μm or less.   An operation panel using the opaque ceramic sintered body according to any one of claims 1 to 3.

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