JP5826062B2 - Light-emitting element mounting substrate and light-emitting device using the same - Google Patents

Description

  The present invention relates to a light-emitting element mounting substrate having high reflectivity and a light-emitting device using the same.

  In recent years, from the viewpoint of energy saving and environmental conservation, LCD televisions and backlights for liquid crystal screens and LEDs (Light Emission Diodes) for general household lighting have been developed. Light-emitting devices using LEDs as light-emitting elements are attracting attention because they have many excellent features, such as about 10 times the life of fluorescent lamps and incandescent bulbs, and about 1/10 of the electricity bill.

  Conventionally, this type of light-emitting device has a configuration in which LED-type light-emitting elements are mounted on various substrates, and the light-emitting elements are connected to electrode patterns formed on the various substrates by wire bonding or bump mounting. Yes.

  Further, as shown in FIGS. 6A and 6B, as the light emitting element mounting substrate 101, a substrate (base portion) on which the light emitting element 103 is mounted in order to increase the light emission efficiency of light emitted from the light emitting element 103. 105) has been proposed in which a so-called frame portion 107 having a wall surface 106 surrounding the light emitting element 103 is provided (see, for example, Patent Document 1).

  Among them, not only has high reflectivity, but also has higher thermal conductivity and mechanical strength, superior heat resistance and durability, compared to the synthetic resin used for the conventional light emitting element mounting substrate 101, A light emitting element mounting substrate 101 based on alumina ceramics or glass ceramics has attracted attention because it does not deteriorate even when exposed to ultraviolet rays for a long time.

  Further, in order to improve the emission intensity of white light from the light emitting element 103, the silver having the highest reflectance at a wavelength near 460 nm is formed on the entire inner wall surface 106 of the frame portion 107 of the light emitting element mounting substrate 101. There has been proposed a film in which an (Ag) film 109 is formed and used as a reflector (see, for example, Patent Document 2).

  However, when the silver film 109 is formed on the entire inner wall 106 of the frame body portion 107, the emission intensity is increased, but the cost of forming the silver film 109 is increased, resulting in an increase in cost. is there.

JP 2006-261290 A JP 2007-158211 A

  Accordingly, an object of the present invention is to provide a light emitting element mounting substrate capable of reducing the cost and increasing the light emission intensity even when the inner wall of the frame body has a silver film, and a light emitting device using the same. And

The substrate for mounting a light emitting element of the present invention is composed of a sintered body made of glass ceramics, and has a base portion having a light emitting element mounting surface in the center and is disposed so as to surround the mounting surface on the base portion. And a silver film formed on the inner wall of the frame body, wherein the frame body part faces diagonally when viewed in plan. The silver film is provided in a region of an inner wall excluding a portion facing the corner, and the silver film is provided in a direction around the inner wall. And the portion where the silver film is not provided are alternately arranged, the silver film is embedded in the inner wall flush with the portion where the silver film is provided, and The porosity in the sintered body is different from the portion where the silver film is not provided. Ri, Ru higher Monodea than the porosity of the sintered body portion porosity of the film of the silver is provided in the sintered body portion layer of the silver is not provided.

  The light emitting device of the present invention is characterized in that a light emitting element is provided in the mounting portion of the light emitting element mounting substrate.

  ADVANTAGE OF THE INVENTION According to this invention, even when it has a silver film on the inner wall of a frame part, while being able to reduce cost, the light emitting element mounting substrate which can make luminous intensity high, and a light-emitting device using the same can be obtained.

(A) and (b) are the cross-sectional schematic diagram and top view which show typically an example of the light emitting element mounting substrate of this embodiment. It is an enlarged view of A part and B part of Drawing 1 (b). It is a top view which shows the pattern in which the part in which the film | membrane of silver is not provided is provided in the direction of the edge of a frame part. It is a cross-sectional schematic diagram which shows the light-emitting device of this embodiment. It is a schematic diagram which shows the manufacturing process of the light emitting element mounting substrate of this embodiment. (A) and (b) are the cross-sectional schematic diagram and top view which show typically an example of the conventional light emitting element mounting substrate.

  FIGS. 1A and 1B are a schematic cross-sectional view and a plan view schematically showing an example of a light-emitting element mounting substrate according to the present embodiment. FIG. 2 is an enlarged view of a portion A and a portion B in FIG.

  The light emitting element mounting substrate of the present embodiment includes a base portion 3 having a mounting surface 1 for mounting a light emitting element, and a frame body portion 5 disposed so as to surround the mounting surface 1. Both the base body portion 3 and the frame body portion 5 are made of a sintered body made of glass ceramics.

  Although the silver film 11 is provided on the inner wall 9 of the frame body part 5, the frame body part 5 in this embodiment is alternately arranged in a direction in which the silver film 11 circulates around the inner wall 9. . In other words, the inner wall 9 of the frame body portion 9 has a configuration in which the portions 11 a where the silver film 11 is provided and the portions 11 b where the silver film 11 is not provided are alternately arranged in a direction around the inner wall 9. ing.

  Further, the portion 11a provided with the silver film and the portion 11b not provided with the silver film have different porosity in the sintered body, and the sintered body of the portion 11b provided with no silver film. The porosity of (the region B in FIG. 1B) is higher than the porosity of the sintered body of the portion 11a provided with the silver film (the region A in FIG. 1B).

  Thereby, even when the inner wall 9 of the frame body part 5 has the silver film 11, the silver film 11 formed on the inner wall 9 of the frame body part 5 is partially formed instead of the entire inner wall 9. As compared with the case where the silver film 11 is formed on the entire inner wall 9 of the frame portion 5, the cost of the silver film 11 can be reduced, and a light emitting element mounting substrate capable of increasing the light emission intensity can be obtained.

Further, in this light emitting element mounting substrate, the portion 11b of the frame 5 where the silver film is not provided
The porosity of the sintered body is higher than the porosity of the sintered body of the portion 11a provided with the silver film. Even if the sintered body is made of glass ceramics, if the porosity in the sintered body is increased, light can be scattered by the pores 12, so that the silver film 11 is provided on the inner wall 9 of the frame body portion 5. Even if it is not, a high reflectance can be obtained by the sintered body itself of the frame portion 5.

  On the other hand, in the structure where there is no difference in porosity of the sintered body between the portion 11a provided with the silver film of the frame body portion 5 and the portion 11b provided with no silver film, the silver portion of the frame body portion 5 is formed. In the portion 11b where the film is not provided, the light transmittance becomes high and it becomes difficult to obtain a high light reflectance.

  In the light emitting element mounting substrate of the present embodiment, the portion 11b of the frame body portion 5 where the silver film is not provided is, for example, in a cross-sectional view as compared with the portion 11a where the silver film is provided. In addition, the number of pores 7 present per unit area should be large.

  Here, the porosity of the sintered bodies is different because, for example, the pores of the respective sintered bodies of the portion 11a provided with the silver film and the portion 11b provided with no silver film of the frame body portion 5 are used. When the rate is obtained, the difference in porosity between the two is 0.5% or more.

  On the other hand, the structure having no difference in the porosity of the sintered body is, for example, the respective sintered bodies of the portion 11a provided with the silver film and the portion 11b provided with no silver film of the frame portion 5. This is a case where the difference in porosity between the two is 0.2% or less.

  Since the base body part 3 and the frame body part 5 constituting such a light emitting element mounting substrate can improve heat dissipation, the sintered body preferably has a porosity of 5% or less.

  Moreover, it is good for the base | substrate part 3 and the frame part 5 to be integrally formed by the point that mechanical strength can be made high. Here, the fact that the base body portion 3 and the frame body portion 5 are integrally formed means that the frame body portion 5 and the base body portion 3 are simultaneously fired and sintered.

  In the light emitting element mounting substrate, the base body 3 and the frame body 5 are preferably made of the same material. When the base body 3 and the frame body 5 are made of the same material, when the base body 3 and the frame body 5 are sintered at the same time, the sintering speed of the base body 3 and the frame body 5 is close. Can be reduced. In this case, the same material means that the ceramic components of the main components contained in the base body portion 3 and the frame body portion 5 are the same. Here, the main component means a glass component and ceramic particles contained in the base body portion 3 and the frame body portion 5, and refers to a case where the combined content is 80% by mass or more.

  The porosity of the sintered body is determined by image analysis of the total area of pores found on the photograph, using an electron micrograph of the sample whose cross-section is polished, and then the total area of the pores is the area of the photograph. Divide and seek. In this case, pores having a maximum diameter of 0.1 μm or more are selected, and pores smaller than that are excluded.

  In the light emitting element mounting substrate of the present embodiment, it is desirable that the silver film 11 is embedded in the inner wall 9 of the frame body portion 5 in a flush manner. If the silver film 11 is embedded flush with the inner wall 9 of the frame body part 5, there is no step between the silver film 11 and the inner wall of the frame body part 5. Light reflection can be suppressed, and the light reflectance can be further increased.

Further, in the light emitting element mounting substrate of the present embodiment, the frame body portion 5 has a mortar shape in which the wall surface 9 of the portion surrounding the mounting surface 1 has an opening diameter on the upper side, and the silver film 11 is It is desirable to have a shape that covers from the lower end 5a to the upper end 5b of the frame body part 5 in contact with the mounting surface 1 of the base body part 3. When the silver film 11 has a shape covering the lower end 5a to the upper end 5b of the frame body part 5 in contact with the mounting surface 1 of the base body part 3, light is widely reflected from the opening of the mortar-shaped frame body part 5. Is possible.

  In this case, it is desirable that the inner wall 9 of the frame body portion 5 is curved in a concave shape from the mounting surface 1 toward the upper side. If the inner wall 9 of the frame 5 is curved concavely from the mounting surface 1 toward the upper side, the light reflecting area can be increased compared to the case where the inner wall 9 is flat. Even when the film 11 is partially formed on the inner wall 9 of the frame 5, the reflectance of light emitted from the light emitting element can be further increased.

  In addition, in the light emitting element mounting substrate of this embodiment, the missing part of the silver film 11 is, for example, at the position shown in FIG. Although it may be provided at a position facing the side, more preferably, as shown in FIG. 1B, the frame body portion 5 has a rectangular shape having corner portions 5c at opposite positions on the diagonal line. The silver film 11 is provided in the region of the inner wall 9 excluding the portion 5d in the direction of the opposite corner 5c (in the normal direction from the inner wall 9 indicated by the arrow H in FIG. 1B). desirable.

  As shown in FIG. 1B, the corner portion 5c of the frame body portion 5 has a thickness t1 that is thicker than the thickness t2 of the side 5e other than the corner portion 5c of the frame body portion 5. For this reason, the corner 5c of the frame 5 is less likely to transmit light than the side 5e. A structure in which the thickness of the frame portion 5 is thin and the silver film 11 is formed on the inner wall 9 of the side 5e where light is easily transmitted, and the silver film 11 is not provided on the corner portion 5c where light is less likely to transmit than the side 5e side. Then, the corner 5c of the frame part 5 becomes a portion 11b where the silver film is not provided, and the portion 11b where the silver film is not provided is compared with the portion 11a where the silver film is provided. The sintered body has a high porosity. For this reason, light transmission can be further suppressed, and conversely, the light reflectance can be increased.

  In this case, the thickness t1 of the corner 5c of the frame 5 is preferably 100 to 1000 μm, and the thickness t2 of the side 5e is preferably 80 to 800 μm.

  FIG. 4 is a schematic cross-sectional view showing the light emitting device of this embodiment. The light emitting device of this embodiment is characterized in that the light emitting element 20 is provided in the mounting portion 1 of the light emitting element mounting substrate described above. That is, in this light emitting device, on the inner wall 9 of the frame 5, the portions 11 a where the silver film is provided and the portions 11 b where the silver film is not provided are alternately arranged in a direction around the inner wall 9. The portion 11a where the silver film is provided and the portion 11b where the silver film is not provided have different porosity in the sintered body, and the portion 11b where the silver film is not provided is sintered. A substrate having a feature that the porosity of the bonded body is higher than the porosity of the sintered body of the portion 11a provided with the silver film is employed.

  With such a configuration, the area occupied by the silver film 11 formed partially on the inner wall 9 of the frame body part 5 on the inner wall 9 of the frame body part 5 is not the entire surface of the inner wall 9, but is partial. Compared with the case where the silver film 11 is formed on the entire inner wall 9 of the body part 5, a light emitting device that is low in cost spent on the silver film 11 can be obtained.

  Further, the light-emitting element mounting substrate constituting this light-emitting device is obtained by baking the portion 11a in which the porosity in the sintered body of the portion 11b of the frame body portion 5 where the silver film is not provided is provided. Since the porosity of the bonded body is higher, it becomes possible to scatter light more in the sintered body. As a result, even if the inner wall 9 of the frame body portion 5 is not provided with a silver film. A high reflectance can be obtained by the sintered body itself of the frame body part 5. Accordingly, light emitted from the light emitting element 11 can be emitted from the frame body portion 5 with high directivity and high efficiency, and a low-cost light emitting device can be obtained.

  In addition, the light emitting element mounting substrate of this embodiment may be provided with a conductor layer for connecting to the light emitting element or an external power source on the surface or inside thereof as necessary.

  Next, a method for manufacturing the light emitting element mounting substrate and the light emitting device of the present embodiment will be described. FIG. 5 is a schematic view showing a manufacturing process of the light emitting element mounting substrate of the present embodiment. Here, FIG.5 (c) is sectional drawing in the GG line of FIG.5 (b).

First, as shown in FIG. 5A, a sheet-like molded body 21 for forming the base body portion 3 and the frame body portion 5 is produced. For example, a mixed powder obtained by mixing glass powder such as borosilicate glass and Al ₂ O ₃ powder is used.

  Next, an organic binder is added to the mixed powder together with a solvent to prepare a slurry or a kneaded product, which is then formed into a sheet shape using a molding method such as a press method, a doctor blade method, a rolling method, or an injection method. Formed body 21 is formed.

  Next, as shown in FIGS. 5B and 5C, a conductor pattern 22 to be a silver film is partially formed on the surface of the sheet-like molded body 21. At this time, the thickness of the conductor pattern 22 is preferably 10 to 30 μm on average because it prevents deformation and breakage after pressurization and partially increases the density of the lower sheet-like molded body 21.

  Next, as shown in FIG. 5 (d), a mold having a convex portion 23 on one surface is prepared, and the sheet-like molded body 21 on which the conductor pattern 22 is formed is press-molded using this mold. Then, a molded body 25 in which a portion corresponding to the convex portion 23 becomes a concave portion is formed.

  In the press molding process, among the sheet-shaped molded body 21 pressed by the convex portion 23 of the mold, the portion of the sheet-shaped molded body 21 below the conductor pattern 22 (reference numeral 23a in FIG. 5B) The green density after pressurization is higher than the portion without the conductor pattern 22 (reference numeral 23b in FIG. 5B).

  Next, the molded body 25 is fired under a predetermined temperature condition, whereby a light emitting element mounting substrate can be obtained.

  In the thus obtained light emitting element mounting substrate, the sintered state after firing is different between the portion 23a having the conductor pattern 22 and the portion 23b having no conductor pattern 22 in the molded body 25 depending on the raw density. come.

  The sheet-like molded body 21 in the portion 23b without the conductor pattern 22 has a low density, and in the state of the molded body 25, the glass powder and ceramic powder are in contact with each other than the sheet-like molded body 21 in the portion 21a with the conductor pattern 22. Since the direction is weaker, the diffusion of the components of the glass powder and the ceramic powder is slower in the firing process than the glass powder and the ceramic powder of the sheet-like molded body 21 of the portion 21a where the conductor pattern 22 is present. For this reason, the densification of the sheet-like molded body 21 in the portion 21 b without the conductor pattern 22 is slower than the densification of the sheet-like molded body 21 in the portion 21 a with the conductor pattern 22.

  On the other hand, the sheet-like molded body 21 of the portion 21a with the conductor pattern 22 is in the state of the molded body 25, and the glass powder and the ceramic powder are in close contact with the sheet-like molded body 21 of the portion 21b without the conductor pattern 22. The green density is high. For this reason, the components of the glass powder and the ceramic powder are easily diffused during the firing process, which facilitates densification.

As a result, when the molded body 25 is sintered, the sheet-like molded body 21 of the portion 21b without the conductor pattern 22 has a low degree of densification, so that the porosity in the sintered body is increased. Since the sheet-like molded body 21 of the portion 21a where the conductor pattern 22 having the higher density of the body 25 is present is easily densified, the porosity of the sintered body can be lowered.

  Thus, the portions 11a provided with the silver film and the portions 11b not provided with the silver film are alternately arranged in the direction around the inner wall 9 of the frame body portion 5, and the silver film was provided. The porosity of the sintered body is different between the portion 11a and the portion 11b where the silver film is not provided, and the porosity of the sintered body of the portion 11b where the silver film is not provided is that of the silver film. A light emitting element mounting substrate higher than the porosity of the sintered body of the provided portion 11a can be obtained.

After mixing 60% by mass of borosilicate glass powder and 40% by mass of Al ₂ O ₃ powder, 19% by mass of acrylic binder as organic binder, 3% by mass of paraffin wax as wax, and as organic solvent After preparing a slurry by mixing toluene, a sheet-like molded article having an average thickness of 800 μm was prepared by a doctor blade method.

  Next, a conductor pattern was formed on the surface of the obtained sheet-like molded body. The thickness of the conductor pattern was about 20 μm. The conductor pattern is arranged as shown in FIG. 5B (sample No. 1), and the portion where the conductor pattern is not printed is arranged in the direction of the side of the frame as shown in FIG. 3 (sample No. .2) and three types of shapes in which the inner wall of the frame portion is curved from the upper end to the lower end and the conductor pattern is arranged as shown in FIG. 5B. In this case, the proportion of the missing portion of the silver film is 30% when the circumference on the outer peripheral side is 100% in the shape of the silver film shown in FIG. 1B (and FIG. 3). I tried to become.

  Next, using the mold having the structure shown in FIG. 5 (d), a heat press is performed at a temperature of 80 ° C., and the structure is cut and cut as shown on the lower side of the mold in FIG. 5 (d). The formed body was formed. Next, it baked for 1 hour at the temperature of 910-950 degreeC in air | atmosphere.

  Each of the produced light emitting element mounting substrates has a mortar shape in which the wall surface of the portion surrounding the mounting surface has an opening diameter on the upper side, and the conductor pattern is flush with the inner wall of the frame portion. Was buried like that.

  As a comparative example, the following samples were produced by the same method. Sample No. 4 is obtained by forming a conductor pattern as shown in FIG. No. 5 shows a sheet-like molded body that is pressed with a mold as shown in FIG. 5D, and then a conductor pattern as shown in FIG. 5B is formed on the inner wall of the formed frame body portion. .

  The obtained light emitting element mounting substrate has a plane area of 3 mm × 3 mm, a thickness of the frame portion (a thickness at a height of the mounting portion on the surface of the base portion) of 300 μm, and a height from the mounting surface of the frame portion. Was 200 μm (the thickness of the region of the mounting surface of the base portion was 400 μm).

  In addition, an LED element was mounted on the mounting surface of the obtained light-emitting element mounting substrate, the light-emitting element was connected to a power source with a conductive wire, and no defect portion was provided in the silver film. The emission intensity ratio of each sample (Sample Nos. 1, 2, 4, and 5) when the emission intensity of No. 3 was taken as 100% was determined.

  The porosity of the sintered body is determined by cutting the frame part of the substrate, polishing the cross section, taking a cross-sectional photograph using an electron microscope, and imaging the total area of the pores recognized in the area per unit area on the photograph. It was obtained by analysis, and then obtained by dividing the total area of the pores by the unit area of the photograph. In this case, pores having a maximum diameter of 0.1 μm or more were selected, and pores smaller than that were excluded. The results are shown in Table 1.

  As can be seen from Table 1, the sample No. 1 in which the porosity of the part where the silver film is not provided is higher than that of the part where the silver film is provided. 1 to 3 had a luminous intensity ratio of 75% or more. In No. 5, the porosity of the portion of the frame portion where the silver film was not provided was as dense as 1.5%, so that light transmission increased from the side surface of the frame portion, and the emission intensity was 70%.

  Sample No. 1 to 3 are intended to reduce the cost of silver by the ratio of the portion where the silver film is not provided, as compared to the sample (sample No. 4) in which the silver film is formed on the entire inner wall of the frame portion. I was able to.

1 .... Mounting surface 3 ... Base part 5 ... Frame 5a ... Lower end 5b of frame 5 ... The upper end 5c of the frame body portion .... the corner portion 5d of the frame body portion .... the portion 5e in which the direction of the corner portion of the frame body portion is a normal direction .... the frame body portion. Side 7 ··································································· Silver film 11a Part 12 where silver film is not provided... Pore 20... Light emitting element 21... Sheet-like molded body 21 a.・ ・ ・ ・ Part 23 without conductor pattern ・ ・ ・ ・ ・ ・ Projection 25 ・ ・ ・ ・ ・ ・ Molded body

Claims (3)

A base part having a light emitting element mounting surface at the center, a frame part disposed so as to surround the mounting surface on the base part, both made of a sintered body made of glass ceramics, and the frame part A silver film formed on the inner wall of the light emitting device mounting substrate,
The frame body portion has a rectangular shape having corner portions at opposing positions on a diagonal when viewed in plan, and the silver film is provided in a region of an inner wall excluding a portion facing the corner portions. In the direction of circling the inner wall, the portion provided with the silver film and the portion not provided with the silver film are alternately arranged,
The silver film is flush with the inner wall;
The portion in which the silver film is provided and the portion in which the silver film is not provided have different porosity in the sintered body, and the sintered body in a portion where the silver film is not provided A substrate for mounting a light emitting element, wherein the porosity of the sintered body is higher than the porosity of the sintered body in the portion where the silver film is provided.   The frame body has a mortar shape in which the wall surface of the portion surrounding the mounting surface increases the opening diameter upward, and the silver film is in contact with the mounting surface of the base body at the lower end of the frame body portion The light emitting element mounting substrate according to claim 1, wherein the light emitting element mounting substrate has a shape covering from the top to the top. Emitting apparatus characterized by comprising a light emitting element to the mounting portion of the light-emitting element mounting substrate according to claim 1 or 2.