JP2006066409A - Wiring board for light emitting element, manufacturing method thereof and light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board for light emitting element which is superior in heat dissipation and mounting reliability. <P>SOLUTION: The wiring board 11 for light emitting element is provided with an insulating substrate 1 formed of tabular ceramics, conductor layers 3, 5 and 7 formed in the surface or the inner of the insulating substrate 1, and a loading part 9 loading the light emitting element 21 on one main face 1a of the insulating substrate 1. A penetration metal 8 having thermal conductivity higher than the insulating substrate 1 is arranged by making it pass through the insulating substrate 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light emitting element wiring board and a light emitting device for mounting a light emitting element such as a light emitting diode, and a method of manufacturing the light emitting element wiring board.

  Conventionally, light emitting devices using LEDs have been used for various applications because of their extremely high luminous efficiency and the small amount of heat generated with light emission compared to incandescent bulbs. However, since the amount of emitted light is small compared to incandescent bulbs, fluorescent lamps, etc., it is used not for illumination but as a display light source, and the energization amount is very small at about 30 mA. And since the mounting form has a small energization amount and a small amount of heat generation, a so-called shell type in which a light emitting element is embedded in a resin dominates (see Patent Document 1).

In recent years, with the increase in brightness and whiteness of light-emitting devices using light-emitting elements, light-emitting devices have been frequently used for backlights of mobile phones, large liquid crystal TVs, and the like. However, as the brightness of light emitting elements increases, the heat generated from the light emitting device also increases, and in order to eliminate the decrease in the brightness of the light emitting elements, such heat dissipation that dissipates such heat more quickly than the elements is high. A wiring board for a light emitting element having the above is required (see Patent Documents 2 and 3).
JP 2002-124790 A Japanese Patent Laid-Open No. 11-112025 JP 2003-347600 A

However, the alumina material conventionally used for the insulating substrate of the wiring board has a low thermal conductivity of about 15 W / m · K, so aluminum nitride having a high thermal conductivity has begun to attract attention as an alternative. However, since aluminum nitride has high raw material costs and is difficult to sinter, it needs to be fired at a high temperature, has a high process cost, and has a low coefficient of thermal expansion of 4 to 5 × 10 ⁻⁶ / ° C. When mounted on a printed circuit board having a thermal expansion coefficient of 10 × 10 ⁻⁶ / ° C. or higher, which is a product, there is a problem that connection reliability is impaired due to a difference in thermal expansion.

  On the other hand, when a resin-based wiring board is used, the thermal expansion coefficient approaches that of the printed circuit board, so there is no problem of mounting reliability between the resin-based wiring board and the printed circuit board. Thermal conductivity is very low at 0.05 W / m · K, it cannot deal with the problem of heat at all, and when used for a long time in the near-ultraviolet wavelength band, the substrate becomes blackened and the luminance decreases. However, a wiring board that is inexpensive, excellent in heat conduction, and excellent in mounting reliability has not yet been provided.

  Accordingly, an object of the present invention is to provide a light-emitting element wiring board and a light-emitting device that are inexpensive and excellent in heat dissipation and mounting reliability, and a method for manufacturing the light-emitting element wiring board.

  The wiring substrate for a light-emitting element of the present invention includes at least a flat insulating substrate made of ceramic fired at a temperature exceeding 1050 ° C., and a conductor layer formed on at least one of the surface or the inside of the insulating substrate, A wiring board for a light-emitting element comprising a mounting portion for mounting a light-emitting element on one main surface of the insulating base, having a thermal conductivity higher than that of the insulating base and co-fired with the insulating base A through metal body is provided so as to penetrate the insulating base.

  In the light emitting element wiring board of the present invention, it is preferable that the through metal body has a cross-sectional area larger than a mounting area of the light emitting element mounted on the light emitting element wiring board.

  In the wiring board for a light emitting element of the present invention, it is preferable that the through metal body is a composite containing at least a metal material and a ceramic material.

  In the wiring board for a light emitting device of the present invention, it is desirable that the through metal body forms an electric circuit.

  In the light-emitting element wiring board of the present invention, it is desirable that at least one end face of the through metal body is covered with an insulating film.

In the light emitting element wiring board of the present invention, it is desirable that the insulating base has a thermal conductivity of 30 W / m · K or more and a thermal expansion coefficient of 8.5 × 10 ⁻⁶ / ° C. or more.

  In the light-emitting element wiring board of the present invention, it is desirable that the three-point bending strength of the insulating base is 350 MPa or more and the total reflectance is 70% or more.

  In the wiring board for a light emitting device of the present invention, it is preferable that the insulating base is made of a MgO-based sintered body having MgO as a main crystal phase.

The wiring substrate for light-emitting element of the present invention, the insulating substrate, Al ₂ O ₃ that is desirable of Al ₂ O ₃ quality sintered body composed mainly crystalline phase.

  In the light-emitting element wiring board of the present invention, it is desirable that the conductor layer and the penetrating metal body have at least one of W, Mo, Cu, and Ag as a main component.

In the wiring board for a light emitting device of the present invention, the thermal conductivity of the penetrating metal body is 80 W / m · K or more, and the thermal expansion difference Δα with the insulating substrate is 4 × 10 ⁻⁶ / ° C. or less. Is desirable.

  The wiring board for a light emitting element of the present invention may be formed by using at least one of metal, ceramics, and resin as a boundary between the insulating substrate and the penetrating metal body formed on the main surface of the wiring board for the light emitting element. It is desirable to coat with a coating layer as a main component.

  In the light-emitting element wiring board according to the present invention, it is preferable that a frame for housing the light-emitting element is formed on the main surface on the side where the mounting portion of the light-emitting element wiring board is formed.

  In addition, a light emitting device in which a light emitting element is mounted on the wiring board for a light emitting element of the present invention described above is desirable. By mounting the light-emitting element on the light-emitting element wiring substrate, heat generated from the light-emitting element can be quickly released outside the apparatus, so that a light-emitting device with less luminance reduction due to heat generation can be obtained.

  The method for manufacturing a wiring board for a light-emitting element according to the present invention includes a step of forming a metal sheet having substantially the same thickness as a ceramic green sheet so as to penetrate the ceramic green sheet, and producing the composite molded body, And a step of producing an insulating substrate in which a through metal body having substantially the same thickness as that of the insulating base is formed so as to penetrate the insulating base.

  The method for manufacturing a wiring board for a light-emitting element according to the present invention includes a step of forming a metal sheet having substantially the same thickness as the ceramic green sheet so as to penetrate the ceramic green sheet, and producing the composite molded body, A laminated body and at least one of another composite molded body or another ceramic green sheet to produce a composite laminated body, and a step of simultaneously firing the composite laminated body It is characterized by doing.

  The wiring substrate for a light-emitting element of the present invention has a higher thermal conductivity than a resin mold substrate by forming an insulating base with ceramics fired at a temperature exceeding 1050 ° C., and has a molecular structure by a light source over a long period of time. Since there is no change, there is almost no change in color tone (blackening or the like) or deterioration of characteristics, and high reliability is achieved. In addition, by providing a penetrating metal body having a higher thermal conductivity than the insulating base so as to penetrate the insulating base, heat generated from the light emitting element can be dissipated more quickly to the outside of the wiring board for the light emitting element. In addition, since the light emitting element can be prevented from being heated excessively, it is possible to prevent a decrease in luminance or to further increase the luminance. The reason why the firing temperature exceeds 1050 ° C. is to distinguish it from a so-called low-temperature fired substrate having a low thermal conductivity.

  Further, by setting the penetrating metal body to a cross-sectional area larger than the mounting area of the light-emitting element mounted on the light-emitting element wiring board, the heat dissipating portion is increased, and the heat generated from the light-emitting element is quickly dissipated. can do.

  Further, by making the through metal body a composite containing at least a metal material and a ceramic material, it becomes easy to control desired characteristics of the through metal body. For example, the coefficient of thermal expansion with the metal body is increased. When approached, cracking between the metal body and the light emitting element wiring board due to mismatch of thermal expansion can be suppressed, and the adhesive strength of the ceramic material to the insulating substrate can be increased. In addition, the through metal body and the insulating base can be fired simultaneously, and the process can be simplified.

  Further, by providing the penetrating metal body with a function as an electric circuit, no conduction terminal is required, and the wiring board for the light emitting element can be reduced in size.

  Further, by covering at least one end face of the through metal body with an insulating film, a short circuit with an external terminal can be prevented, and wiring is arranged directly under the through metal body when the light emitting device is mounted on a printed board or the like. This makes it possible to reduce the size of the device. In addition, when the insulating film is formed on the light emitting element mounting side, a short circuit between the light emitting element electrodes can be prevented, and flip chip mounting of the light emitting element can be simplified.

Further, by setting the thermal conductivity of the insulating base to 30 W / m · K or higher and the thermal expansion coefficient to 8.5 × 10 ⁻⁶ / ° C. or higher, the heat dissipation of the insulating base itself can be improved. Since the difference in thermal expansion from the penetrating metal body can be reduced, the bonding reliability between the penetrating metal body and the insulating substrate can be improved. Further, since the thermal expansion coefficient of the insulating base is increased, the metal content of the through metal body can be increased, and the thermal conductivity of the through metal body can be increased.

Further, by setting the three-point bending strength of the insulating base to 350 MPa or more, the strength of the insulating base can be sufficiently increased, and substrate cracking due to stress when mounting the light emitting device on a printed board or the like can be prevented.
Further, by setting the total reflectance to 70% or more, it is possible to prevent the radiated light from the light emitting element from being transmitted through or absorbed by the insulating base, and the light emitting element wiring board having high light emission efficiency. Can be obtained.

Moreover, since the thermal expansion coefficient of the insulating substrate can be controlled to about 10 × 10 ⁻⁶ / ° C. by forming the insulating substrate with an MgO-based sintered body having MgO as the main crystal phase, the general-purpose product 10 × Mounting reliability on a printed circuit board having a thermal expansion coefficient of 10 ⁻⁶ / ° C. or higher can be improved.

Further, the insulating substrate, the Al ₂ O ₃ that is formed by Al ₂ O ₃ quality sintered body composed mainly crystalline phase, it is possible to use inexpensive raw materials, to obtain an inexpensive light emitting element wiring board it can.

  In addition, by forming a conductor layer and a metal body mainly composed of at least one of W, Mo, Cu, and Ag, it is possible to form a surface and an internal wiring by simultaneous firing with an insulating substrate, and heat dissipation is achieved. An excellent and inexpensive wiring board for a light emitting element can be obtained.

Further, by setting the thermal conductivity of the penetrating metal body to 80 W / m · K or more, the heat generated from the light emitting element can be further dissipated quickly, and the thermal expansion difference Δα with respect to the insulating substrate can be reduced to 4 ×. By setting the temperature to 10 ⁻⁶ / ° C. or less, the difference in thermal expansion from the insulating base can be reduced, so that the bonding reliability between the through metal body and the insulating base can be improved.

  Further, the boundary between the insulating substrate and the penetrating metal body formed on the main surface of the wiring board for the light emitting element is covered with a coating layer mainly composed of at least one of metal, ceramics, and resin. Thus, the difference in thermal expansion between the metal body and the insulating substrate can be buffered, and the occurrence of cracks between the boundaries can be suppressed.

  In addition, by providing a frame for housing the light emitting element on the main surface of the mounting portion of the wiring board for the light emitting element, the light emitting element can be protected and a phosphor or the like can be easily disposed around the light emitting element. Can do. In addition, the light emitted from the light emitting element can be reflected by the frame and guided in a predetermined direction.

  According to the light-emitting device of the present invention in which the light-emitting element is mounted on the light-emitting element wiring substrate of the present invention described above, the heat generated from the light-emitting element can be quickly discharged out of the device. Reduction can be suppressed.

  The method for manufacturing a wiring board for a light-emitting element according to the present invention includes a step of forming a metal sheet having substantially the same thickness as a ceramic green sheet so as to penetrate the ceramic green sheet, and producing the composite molded body, And a step of forming an insulating substrate in which a through metal body having substantially the same thickness as the insulating base is formed so as to penetrate through the insulating base.

  The method for manufacturing a wiring board for a light-emitting element according to the present invention includes a step of forming a metal sheet having substantially the same thickness as the ceramic green sheet so as to penetrate the ceramic green sheet, and producing the composite molded body, A laminated body and at least one of another composite molded body or another ceramic green sheet to produce a composite laminated body, and a step of simultaneously firing the composite laminated body It is characterized by using the process to do.

  As shown in FIG. 1A, for example, the wiring substrate for a light emitting element of the present invention has a connection terminal 3 between an insulating base 1 made of ceramics and a light emitting element formed on a main surface 1a of the insulating base 1. The through-electrode 7 provided through the insulating base 1 so as to electrically connect the external electrode terminal 5 formed on the other main surface 1b of the insulating base 1, the connection terminal 5 and the external electrode terminal 5. In addition, the thermal conductivity is higher than that of the insulating base 1 provided through the insulating base 1, and the through-metal body 8 is formed by being fired simultaneously with the insulating base 1.

  A mounting portion 9 for mounting a light emitting element is formed between one connection terminal 3a and the other connection terminal 3b.

  Further, for example, as shown in FIG. 1B, the light emitting element wiring substrate 11 of the present invention is configured by forming a frame 13 for housing the light emitting element to be mounted on the mounting portion 9 side. ing.

  According to the light emitting element wiring substrate 11 of the present invention, the penetrating metal body 8 having a higher thermal conductivity than the insulating base 1 is fired simultaneously with the insulating base 1 and provided through the insulating base 1. is important.

  That is, by providing the penetrating metal body 8 having a higher thermal conductivity than that of the insulating substrate 1, heat generated from the light emitting element can be quickly dissipated using the penetrating metal body 8 as a heat transfer path. It is possible to prevent the light emitting element from being heated and to prevent the luminance of the light emitting element from being lowered. As shown in FIG. 1 (a), the penetrating metal body 8 has a plurality of columnar aggregates as shown in FIG. 1 (b). Form may be sufficient.

  Moreover, it is preferable that the form of the through metal body 8 has a cross-sectional area larger than the mounting area of the light emitting element mounted on the wiring board 11 for the light emitting element, as shown in FIG. By increasing the cross-sectional area of the through metal body 8, the heat radiation portion is increased, and further, heat generated from the light emitting element can be quickly dissipated. In particular, the cross-sectional area of the through metal body 8 is preferably 1.1 times or more, more preferably 1.2 times or more with respect to the mounting area of the light emitting element.

  Here, the through metal body 8 which is an aggregate of a plurality of cylinders as shown in FIG. 1A is generally called a thermal via, and a conductor is formed in a through hole formed in a ceramic green sheet by laser processing or the like. The paste is embedded by screen printing or the like, and is obtained by simultaneous firing. A lump-shaped through metal body 8 as shown in FIG. 1 (b) is made of a ceramic sheet having a thickness substantially the same as that of the ceramic green sheet. The composite molded body 50 is formed so as to penetrate through the green sheet, and is obtained by simultaneous firing.

  The thermal via as shown in FIG. 1A normally has a cylindrical shape with a diameter of about 200 μm. On the other hand, the massive penetrating metal body 8 as shown in FIG. 1B has the same size as the light-emitting element to be mounted, and has a diameter exceeding 1000 μm, for example. . Therefore, higher heat dissipation can be achieved than when thermal vias are used.

  In addition, by using a mixture of metal powder and inorganic powder as the conductive paste that becomes the through metal body 8, for example, a mixture of metal powder and inorganic powder is filled in the through holes formed in the ceramic green sheet. Thus, the light emitting element wiring substrate 11 in which the insulating base 1 and the through metal body 8 are firmly bonded can be easily manufactured.

  Further, the through metal body 8 can be provided with a function as an electric circuit, so that the light emitting element wiring substrate 11 is small in size and excellent in heat dissipation.

  Further, as shown in FIGS. 2A and 2B, at least one end face of the through metal body 8 is covered with the insulating film 6, thereby short-circuiting the through metal body 8 with the connection terminal 3 and the external terminal 5. Can be prevented.

  For example, as shown in FIG. 2A, by forming the insulating film 6 on the main surface 1a on the light emitting element mounting side, it is possible to prevent a short circuit between the electrodes of the mounted light emitting element, and the flip chip mounting of the light emitting element. Can be simplified. For example, as shown in FIG. 2B, when the insulating film 6 is formed on the main surface 1b opposite to the mounting portion 9, the penetrating metal body is used when the light emitting device is mounted on a printed board or the like. Since it becomes possible to arrange wiring directly under 8, it is possible to reduce the size of the device.

  The insulating film 6 is formed of an insulating material. For example, when the insulating film 1 is formed by baking the insulating substrate 1 and the through metal body 8 simultaneously with the same material as the insulating substrate 1, there is no need to increase the number of steps. . Further, the insulating film 6 may be formed of a resin. In this case, after the insulating substrate 1 and the through metal body 8 are simultaneously fired, a slurry-like resin is applied to a predetermined portion and cured. Can be easily formed.

  As shown in FIG. 3, the boundary between the insulating base 1 and the penetrating metal body 8 formed on the main surface of the insulating base 1 is a coating layer mainly composed of at least one of metal, ceramics, and resin. 12 is preferred. By covering the boundary between the penetrating metal body 8 and the insulating substrate 1 with these coating layers 12, the difference in thermal expansion between them can be buffered and the occurrence of cracks at the boundary can be suppressed.

  When this coating layer 12 is formed of metal or ceramics, it is desirable from the standpoint of reducing the number of steps that it is fired simultaneously with the insulating substrate 1. When a resin is used as the coating layer 12, the resin is printed so as to block the boundary between the insulating substrate 1 and the penetrating metal body 8 after the baking process of the insulating substrate 1, and the coating is performed by performing a curing process or the like. Layer 12 can be formed. In addition, when using resin for the coating layer 12, in addition to a resin component, the water resistance and heat dissipation of the coating layer 12 can be improved by containing 10-50 volume% ceramic powder.

  The coating layer 12 may be formed by stacking a plurality of coating layers 12 of different materials. Even if a crack occurs at the boundary between the insulating substrate 1 and the through metal body 8, the crack propagates to the surface layer. Therefore, it is most desirable to form the coating layer 12 containing the resin in the outermost layer.

  In the case of using ceramics as the coating layer 12, it is desirable to use ceramics having the same composition as that used for the insulating substrate 1 from the viewpoints of sinterability and adhesion between the coating layer 12 and the insulating substrate 1.

  When a metal is used as the coating layer 12, using a metal having the same composition as that used for the through metal body 8 is referred to as sinterability and adhesion between the coating layer 12 and the through metal body 8. Desirable from a viewpoint.

  Further, when a metal is used as the coating layer 12, it is desirable to contain ceramic powder because it becomes possible to control the sintering behavior and the thermal expansion coefficient.

  In addition, by setting the thermal conductivity of the insulating base 1 used for the light emitting element wiring substrate 11 to 30 W / m · K or more, heat dissipation from the insulating base itself is improved, and a reduction in luminance of the light emitting element is prevented. It becomes possible. In particular, the thermal conductivity of the insulating substrate 1 is preferably 35 W / m · K or more, more preferably 40 W / m · K or more, and most preferably 45 W / m · K or more. . An insulating substrate of 30 W / m · K or higher can be produced by using, for example, high-purity alumina or MgO having a purity of 99% or higher. Further, the insulating base 1 having 40 W / m · K or more can be produced by using MgO.

The thermal expansion coefficient of the insulating substrate 1 is desirably 8.5 × 10 ⁻⁶ / ° C. or more. When such an insulating substrate 1 is used, the insulating substrate 1, the through metal body 8, Since the difference in thermal expansion from the external printed circuit board can be reduced, the connection reliability between the insulating base 1, the through metal body 8 and the external printed circuit board can be remarkably increased. In addition, it goes without saying that the bonding reliability with the resin provided to cover the mounted light emitting element is also improved.

The thermal expansion coefficient of the insulating substrate 1 is particularly preferably 9.0 × 10 ⁻⁶ / ° C. or more, and preferably 10.0 × 10 ⁻⁶ / ° C. or more, for example, 8.5 × The insulating substrate 1 of 10 ⁻⁶ / ° C. or higher can be produced by using forsterite or MgO. Moreover, the insulating substrate 1 of 10.0 × 10 ⁻⁶ / ° C. or more can be produced by using MgO.

  In addition, it is desirable that the three-point bending strength of the insulating substrate 1 used for the light emitting element wiring substrate 11 is 350 MPa or more and the total reflectance is 70% or more. When such an insulating substrate is used, the insulating substrate is used. Since the strength of itself is high, it is possible to prevent the substrate from being cracked due to stress when the light emitting device is mounted on a printed board or the like. In particular, the three-point bending strength of the insulating substrate 1 is preferably 400 MPa or more, and preferably 450 MPa or more. For example, by using alumina or MgO for the insulating substrate 1, the insulating substrate 1 that satisfies the above conditions is manufactured. Can do.

  Further, by increasing the reflectance of the insulating substrate 1, it is possible to prevent the radiated light from the light emitting element from being transmitted through the insulating substrate 1 or absorbed by the insulating substrate 1, and to improve the luminous efficiency. A good light emitting element wiring substrate 11 can be obtained. In particular, the total reflectance of the insulating substrate 1 is preferably 72% or more, preferably 80% or more, and most preferably 83% or more. Such an insulating substrate 1 is, for example, white alumina. Or MgO can be used.

For example, since the thermal expansion coefficient of the insulating base can be controlled to about 10 × 10 ⁻⁶ / ° C. by using an MgO-based sintered body having MgO as the main crystal phase as the insulating base 1, Mounting reliability on a printed circuit board having a thermal expansion coefficient of 10 × 10 ⁻⁶ / ° C. or more can be improved. In addition, a thermal conductivity coefficient of 30 W / m · K or more can be achieved.

  The MgO-based sintered body having MgO as the main crystal phase is such that, for example, the peak of MgO is detected as the main peak by X-ray diffraction, and the volume ratio of MgO crystals is 50% by volume. It is desirable to contain above.

Moreover, such a sintered body is made of, for example, MgO powder having an average particle diameter of 0.1 to 8 μm and a purity of 99% or more, such as Y ₂ O ₃ or Yb ₂ O ₃ having an average particle diameter of 0.1 to 8 μm. A molded body to which at least one kind of sintering aid selected from the group consisting of rare earth element oxides, Al ₂ O ₃ , SiO ₂ , CaO, SrO, BaO, B ₂ O ₃ and ZrO ₂ was added is 1300 to 1700 ° C. It is obtained by firing in the temperature range. Alternatively, MgAl ₂ O ₄ containing MgO or MgO · SiO ₂ based composite oxide may be added.

  Then, in order to obtain a dense body having MgO as a main crystal, the amount of the composition other than MgO such as a sintering aid is desirably 30% by mass or less, and more desirably 20% by mass or less. Is desirable. In particular, when the addition amount of a composition other than MgO, such as a sintering aid, is 10% by mass or less, most of the obtained insulating substrate 1 can be formed of MgO crystals. These sintering aids are desirably added in an amount of 3% by mass or more, and more preferably 5% by mass or more in order to lower the firing temperature.

Further, when an Al ₂ O ₃ sintered body having Al ₂ O ₃ as a main crystal phase is used as the insulating base 1, an inexpensive raw material can be used, and an inexpensive light-emitting element wiring substrate 11 is obtained. be able to.

Note that the _Al 2 _{O 3} and _Al 2 _{O 3} quality sintered body composed mainly crystalline phase, for example, by X-ray diffraction, is like the peak of _Al 2 _{O 3} is detected as the main peak, Al ₂ It is desirable to contain 50% or more by volume of O ₃ crystals.

Moreover, such a sintered compact is made of, for example, Al ₂ O ₃ powder having an average particle diameter of 1.0 to 2.0 μm and a purity of 99% or more, and Mn ₂ O ₃ having an average particle diameter of 1.0 to 2.0 μm. , SiO ₂ , MgO, SrO, CaO. A molded body to which at least one sintering aid selected from the group consisting of CaO is added is fired in a temperature range of 1300 to 1500 ° C.

And, for the addition amount of Al ₂ O ₃ other than the compositions, such as sintering aids, in order to obtain a dense body of the Al ₂ O ₃ as a main crystal, preferably 15 wt% or less, more desirably, 10 It is desirable to set it as mass% or less. In particular, when the amount of a composition other than Al ₂ O ₃ such as a sintering aid is set to 15% by mass or less, most of the obtained insulating substrate 1 can be formed of Al ₂ O ₃ crystals. . These sintering aids are desirably added in an amount of 5% by mass or more, and more preferably 7% by mass or more in order to lower the firing temperature. Note that as the ceramic used for the insulating substrate 1, a sintered body having AlN, Si ₃ N ₄ or the like as a main crystal may be used.

A ceramic green sheet which is a sheet-like formed body by, for example, a doctor blade method by adding a binder and a solvent to such a composition containing MgO or Al ₂ O ₃ as a main component. Is made. Next, through holes are formed in the ceramic green sheet, and further, a conductive paste containing at least a metal powder is printed and filled on the surface of the ceramic green sheet or the through holes provided in the ceramic green sheet. For light emitting devices in which ceramic green sheets are laminated and fired in an oxidizing atmosphere, a reducing atmosphere, or an inert atmosphere to form wiring layers such as connection terminals 3, external electrode terminals 5, and through conductors 7 on the surface and inside. The wiring board 11 can be produced. Needless to say, the wiring layer can be formed on the surface of the insulating substrate 1 by a thin film method or by transferring a metal foil onto the surface of the molded body.

  Then, by forming the connection terminal 3, the external electrode terminal 5, the through conductor 7, and the through metal body 8 on the surface or inside of the insulating base 1 in this way, a wiring circuit is formed on the light emitting element wiring substrate 11. be able to.

  Then, the through metal body 8 and the wiring layers 3 and 5 forming these wiring circuits are formed by using at least one of W, Mo, Cu, and Ag as a main component, and simultaneously fired with the insulating substrate 1. The connection terminals 5, the external electrode terminals 5, the through conductors 7, and the through metal bodies 8 can be formed, and the inexpensive light emitting element wiring substrate 11 can be quickly produced.

  In addition to the above metal, the through metal body 8 preferably contains ceramic powder in order to control the thermal conductivity, thermal expansion coefficient, and sintering behavior of the through metal body 8. The content is preferably 0 to 5% by weight, more preferably 0 to 4% by weight, and preferably 0 to 3% by weight in order to obtain high thermal conductivity.

  Moreover, the reflectance of the connection terminal 5 and the through metal body 8 can be improved by applying Al or Ag plating to the surfaces of the connection terminal 5 and the through metal body 8.

  Moreover, since the heat conductivity of the penetrating metal body 8 is 80 W / m · K or more, heat generated from the light emitting element can be directly and quickly dissipated, so that stable light emission of the light emitting element can be maintained. It is possible to prevent a decrease in luminance of the light emitting element. The thermal conductivity of the through metal body 8 can be controlled, for example, by appropriately selecting the type of metal used for the through metal body 8. For example, it can control by selecting the ratio of a metal and ceramic powder suitably. As the ceramic powder to be used, those containing the components constituting the insulating substrate 1 are preferable. Further, for example, it is possible to control by using a plurality of kinds of metal powders and changing their ratio.

  The thermal conductivity of the through metal body 8 is particularly preferably 100 W / m · K or more, more preferably 120 W / m · K or more, and most preferably 160 W / m · K or more.

  And the penetration metal object 8 which has such a high thermal conductivity can be formed by making content of Cu which has a high thermal conductivity high. Specifically, the Cu content is preferably 50% by volume or more, and more preferably 60% by volume or more.

Further, in order to improve the adhesion reliability between the penetrating metal body 8 and the insulating substrate 1, it is desirable that the thermal expansion coefficient of the penetrating metal body 8 is close to the thermal expansion coefficient of the insulating substrate 1, and the heat of both By preventing the expansion mismatch, the highly reliable light-emitting element wiring substrate 11 can be obtained. Here, the thermal expansion coefficient of the through metal body 8 can be controlled by appropriately selecting the type of metal used for the through metal body 8. Further, for example, it can be controlled by appropriately selecting the ratio of metal to ceramic powder. Further, for example, control can be performed by using a plurality of types of metal powders and changing their ratio. In particular, the difference in thermal expansion Δα between the insulating substrate 1 and the through metal body 8 is preferably 4.0 × 10 ⁻⁶ / ° C. or less, more preferably 2.0 × 10 ⁻⁶ / ° C. or less, and most preferably. Is preferably 1.0 × 10 ⁻⁶ / ° C. or less.

  Then, by combining Cu having a high thermal conductivity and W having a relatively low thermal expansion coefficient among metals, it has a high thermal conductivity and the difference in thermal expansion coefficient from the insulating base 1 is controlled. The through metal body 8 can be formed.

  Moreover, since the frame 13 is formed of ceramics, the insulating substrate 1 and the frame 13 can be fired at the same time, and the process is simplified. Therefore, the inexpensive light-emitting element wiring substrate 11 is easily manufactured. can do. In addition, since ceramics are excellent in heat resistance and moisture resistance, the light emitting element wiring substrate 11 has excellent durability even when used for a long period of time or under adverse conditions.

In order to further improve durability and reflectivity, a metallized layer formed by simultaneous firing is formed on the surface of the frame 13 made of ceramics, and a plated layer made of Ni, Au, Ag or the like on the surface ( (Not shown) may be formed.

  In addition, by forming the frame body 13 from a metal that is inexpensive and excellent in workability, even the frame body 13 having a complicated shape can be easily manufactured at low cost, and an inexpensive wiring board for a light-emitting element. 11 can be supplied. This metal frame 13 can be suitably formed by Al, Fe-Ni-Co alloy, etc., for example. Further, a plating layer (not shown) made of Ni, Au, Ag or the like may be formed on the surface of the frame 13.

  When the frame body 13 is formed of a metal in this way, a metal layer 17 is previously formed on the main surface 1a of the insulating base 1, and the metal layer 17 and the frame body 13 are, for example, eutectic Ag. -It can braze via the brazing material (not shown) which consists of Cu brazing materials etc.

  Then, for example, as shown in FIG. 4A, an LED chip 21 or the like is mounted as the light emitting element 21 on the wiring board 11 for the light emitting element of the present invention described above, and the light emitting element 21 is fed by the bonding wire 23. Thus, the light emitting element 21 can be made to function, and the heat generated from the light emitting element 21 can be quickly released from the through metal body. By making the thermal expansion coefficient close to that of the printed circuit board, it is possible to suppress mismatch of the thermal expansion coefficient with the printed circuit board and the molding material, and thus the light emitting device 25 with high bonding reliability can be obtained. In addition, by providing a heat sink, it is needless to say that heat dissipation is further improved, and for example, provision of a cooling device such as a heat sink is not excluded.

  Further, an LED chip 21 or the like is mounted on the mounting portion 9 formed on the light emitting element wiring substrate 11 as, for example, the light emitting element 21, and the LED chip 21 and the connection terminal 3 are electrically connected by the bonding wire 23. By supplying power, the light emitted from the light emitting element 21 can be reflected by the insulating base 1 and the frame 13 and guided in a predetermined direction, so that the highly efficient light emitting device 25 is obtained. Further, since the thermal conductivity of the insulating base 1 and the frame 13 is high, heat generated from the light emitting element 21 can be quickly released, and a reduction in luminance due to heat generation can be suppressed.

  4B, in the light emitting device 25 in which the frame body 13 is disposed on the main surface 1a of the light emitting element wiring substrate 11 on the side where the light emitting element 21 is mounted, By housing the light emitting element 21, the light emitting element 21 can be easily protected.

  In the example shown in FIGS. 4A and 4B, the light emitting element 21 is fixed to the light emitting element wiring substrate 11 with an adhesive 29, and power is supplied by the wire bond 23. Needless to say, the connection form with the element wiring substrate 11 may be flip-chip connection.

  Moreover, although the light emitting element 21 is covered with the molding material 31, it may be sealed using a lid (not shown) without using the molding material 31, or the molding material 31 and the lid. And may be used in combination. In the case where the lid is used, and the light emitting element 21 is used, it is desirable that the lid is made of a translucent material such as glass.

  In addition, when mounting the light emitting element 21, you may add the fluorescent substance (not shown) for wavelength-converting the light which the light emitting element 21 radiates | emits to this molding material 31 as needed.

  In the example described above, the example in which the through conductor 7 is provided has been described. However, the through conductor 7 may not be provided, and the insulating base 1 may be laminated in multiple layers. Of course it is good.

  Next, the manufacturing method of the wiring board 11 for light emitting elements of this invention is demonstrated.

  First, the ceramic green sheet 40 that becomes the insulating substrate 1 and the metal sheet 43 that becomes the through metal body 8 are produced by firing.

  The ceramic green sheet 40 is formed into a sheet shape from a ceramic slurry formed from a ceramic powder, a resin, a solvent, and the like by a conventionally known doctor blade method or the like.

  Similarly, the metal sheet 43 is formed into a sheet shape from a metal slurry prepared by mixing a metal powder, a resin, and a solvent in a predetermined ratio by a conventionally known doctor blade method or the like. The metal slurry may contain ceramic powder as necessary.

  The ceramic powder used for the ceramic green sheet 40 and the metal sheet 43, and the metal powder having an average particle diameter of about 0.01 to 10 μm is preferably used, and in particular, powder in the range of 1 to 5 μm is handled and sintered. Excellent binding.

  Next, for example, as shown in FIG. 5A, the ceramic green sheet 40 is disposed on the upper surface of the mold 39 having the punched holes 37.

  Next, as shown in FIG. 5B, a metal sheet 43 is overlaid on the ceramic green sheet 40 described above. The metal sheet 43 preferably has substantially the same thickness as the ceramic green sheet 40.

  Next, as shown in FIG. 5C, the metal sheet 43 is inserted into the ceramic green sheet 40 with the push die 35.

  Next, unnecessary portions of the metal sheet 43 and the ceramic green sheet 40 are removed, so that the metal sheet 43 is formed so as to penetrate a part of the ceramic green sheet 40 as shown in FIG. The composite molded body 50 can be formed.

  If necessary, as shown in FIG. 6A, the composite molded body 50 is laminated with another composite molded body 50 or another ceramic green sheet, so that the multilayer light-emitting element wiring substrate 11 is formed. Can be produced.

  Also, the insulating film 6 is used to cover the main surface side or the opposite surface side surface of the through green metal body 43a of the composite molded body 50 by screen printing using a ceramic slurry containing the same ceramic component as that of the insulating substrate 1. An insulating film 6 that covers the end face of the penetrating metal body 8 as shown in FIGS. 2A and 2B can be formed by forming a molded body to be formed and simultaneously firing.

  The insulating film 6 may be formed of, for example, a resin after the composite molded body 50 is fired.

  Further, as shown in FIG. 6B, a covering layer molded body 44 that becomes the covering layer 12 mainly composed of ceramics so as to cover the exposed boundary between the ceramic green sheet 40 and the penetrating green metal body 43a. Is formed and co-fired to form a light emitting element wiring substrate 11 as shown in FIG.

  Moreover, as shown in FIG.6 (c), the composite molded body 50 forms the coating layer molded body 45 used as the coating layer 12 containing the metal component similar to a penetration metal body, for example, and forms it by baking simultaneously. You can also

  Further, as shown in FIG. 6D, after the composite molded body 50 is fired, a coating layer 46 containing a resin is formed so as to cover the exposed interface between the insulating substrate 1 and the through metal body 8. You can also.

  In forming the coating layer 46, the coating layer 46 is formed by screen printing, and the coating layer 46 formed on the surface of the light-emitting element wiring substrate 11 is cured by heat or light, so that the coating layer having a desired shape is formed. 46 can be formed.

  In addition, the formation of the through metal body 8 is not limited to the above method. For example, a composite molding in which a through hole having a predetermined shape is formed in the ceramic green sheet 40 and a conductive paste containing metal powder is filled in the through hole. It can also be produced by firing the body 50.

  The insulator layer 1 and the penetrating metal body 8 are coated with a paste for forming a coating layer 44 containing ceramics and a coating layer 45 containing the same metal component as the penetrating metal body 8 by screen printing or the like. It is possible to fill a fine gap at the interface of the film, and to achieve the densification of the interface structure more reliably.

MgO powder having a purity of 99% or more and an average particle diameter of 1 μm, Y ₂ O ₃ powder having a purity of 99% or more and an average particle diameter of 1 μm, a purity of 99% or more and an average particle diameter as a raw material powder for an insulating substrate of a wiring board for a light emitting device Using 1.5 μm Al ₂ O ₃ powder with a purity of 99% or more, the raw material powder is mixed in the ratio shown in Table 1, an acrylic binder as a molding organic resin (binder), and toluene as a solvent, The slurry was adjusted. Thereafter, a green sheet was prepared by a doctor blade method.

  Further, some of the wiring boards for light emitting elements have an outer dimension of 10 mm × 10 mm × 2 mm on the side where the mounting portion is formed, an inner diameter on the side in contact with the insulating base is 4 mm, and an inner diameter on the opposite side is 8 mm. A frame body made of the same material as the insulating substrate having a tapered through hole was formed. The light-emitting element wiring board in which the frame body was formed of the same material as the insulating base body was manufactured by forming the insulating base body and the frame body as a single body with a green sheet and performing simultaneous firing.

  Further, using W, Mo, Cu, Ag powder having an average particle diameter of 2 μm and alumina having an average particle diameter of 1.5 μm as a ceramic material, metal powder, inorganic powder, acrylic binder, and acetone are mixed at a ratio shown in Table 1. A conductor paste was prepared by mixing as a solvent.

  In addition, the metal sheet is mixed with the metal powder and inorganic powder shown in Table 1, an acrylic binder as a molding organic resin (binder), and toluene as a solvent at a ratio similar to that of the conductor paste, and a slurry that becomes a metal sheet is mixed. It was adjusted. Thereafter, a metal sheet having substantially the same thickness as the ceramic green sheet was produced by a doctor blade method.

  Then, the ceramic green sheet is punched to form a through hole having a diameter of 100 μm. The through hole is filled with a conductive paste by a screen printing method and printed and applied in a wiring pattern. .

  Then, a through hole is formed at a predetermined position of the ceramic green sheet, and a part of the metal sheet is embedded in the through hole by pressing a through hole forming portion of the ceramic green sheet from the metal sheet. The ceramic green sheet and the metal sheet And a metal sheet to be a through metal body was formed so as to have the shape shown in Table 3. In Table 3, what the shape of the through metal body is described as a lump represents a square-shaped integrated through metal body, and what is described as an aggregate is a plurality of cylinders spaced apart. The formed through metal body is shown.

  The green sheets thus produced were combined, aligned, and laminated and pressure bonded to produce a laminate having an outer shape of 10 mm × 10 mm × thickness of 0.6 mm.

Then, after degreasing in a nitrogen-hydrogen mixed atmosphere at a dew point of + 25 ° C., it was subsequently fired for 2 hours at a maximum temperature of 1300 to 1700 ° C. in a nitrogen-hydrogen mixed atmosphere at a dew point of + 25 ° C. Then, a connection terminal was formed on one main surface of the insulating base, an external electrode terminal was formed on the other main surface, and a light-emitting element wiring board in which both were connected by a through conductor was produced.

Thereafter, Ni, Au and Ag plating were sequentially applied to the surfaces of the connection terminal and the external electrode terminal. Since the chemical resistance of MgO is lower than that of Al ₂ O ₃ or the like, the concentration of the plating treatment solution is reduced and the plating treatment temperature is lowered so that the surface state of the wiring board for light emitting elements does not deteriorate. Then, the plating treatment of the wiring board for light emitting device of the present invention was performed.

Further, as raw material powder, Al ₂ O ₃ powder with a purity of 99% or more and an average particle size of 1.5 μm, Mn ₂ O ₃ powder with a purity of 99% or more and an average particle size of 1.3 μm, purity of 99% or more, average particle size A raw material powder was mixed at a ratio shown in Table 2 using 1.0 μm SiO ₂ powder, an acrylic binder as a molding organic resin (binder), and toluene as a solvent were mixed to prepare a slurry. Thereafter, a ceramic green sheet is produced by a doctor blade method, and some of the wiring boards for light emitting elements have an outer dimension of 10 mm × 10 mm × 2 mm on the side where the mounting portion is formed, A frame made of the same material as that of the insulating substrate having a tapered through hole having an inner diameter of 4 mm on the side in contact with the inner surface and an inner diameter of 8 mm on the opposite side was formed. The light-emitting element wiring board in which the frame body was formed of the same material as the insulating base body was manufactured by forming the insulating base body and the frame body as a single body with a green sheet and performing simultaneous firing.

  In addition, the conductor paste and the metal sheet were prepared by using the same raw materials as those used when MgO was the main component and adjusting the ratio in Table 2 in the same process.

  Then, in the same process as when MgO was the main component, a conductor paste was printed on the ceramic green sheet, and a metal sheet to be a through metal body was embedded. Subsequently, a coating layer having a thickness of about 20 μm containing ceramic was formed so as to cover the exposed interface between the ceramic green sheet and the penetrating green metal body. Further, in the same process, a coating layer containing the same metal component as that of the through metal body was formed, and co-firing was performed at a maximum temperature of 1300 to 1500 ° C. to produce a wiring board for a light emitting element.

  For some samples, after firing, an epoxy resin was applied to the boundary between the insulating substrate 1 and the penetrating metal body 8 and cured under conditions of 150 ° C. for 1 hour, and a coating layer having a thickness of about 20 μm. Formed.

Moreover, as a metal frame, an Al metal frame having a thermal expansion coefficient of 23 × 10 ⁻⁶ / ° C. and a thermal conductivity of 238 W / m · K, and a thermal expansion coefficient of 6 × 10 ⁻⁶ / ° C. A metal frame made of Fe—Ni—Co alloy having a thermal conductivity of 17 W / m · K was used. In addition, for a light emitting element wiring board provided with a metal frame, a metal layer is formed on a portion where the frame on the mounting portion side of the insulating substrate is mounted using a conductive paste that forms connection terminals and external electrode terminals. Then, the frame body was bonded to an insulating substrate under the condition of 850 ° C. using a eutectic Ag—Cu brazing material.

An LED chip, which is a light emitting element with an output of 1.5 W, is mounted on the mounting part using an epoxy resin as an adhesive on these wiring boards for light emitting elements, and the LED chip and the connection terminal are connected by a bonding wire. The chip and the connection terminal were covered with a mold material made of an epoxy resin having a thermal expansion coefficient of 40 × 10 ⁻⁶ / ° C. to obtain a light emitting device.

  The obtained light emitting device was subjected to a temperature cycle test of -55 ° C. to 125 ° C. for 1000 cycles, and after the test, the peeling state of the adhesion interface between the through metal body and the insulating substrate was confirmed.

  Further, a current of 0.4 A was passed through the light emitting device, and the total radiant flux was measured after 1 hour.

The obtained insulating substrate was pulverized, and the main crystal phase of the insulating substrate was identified by X-ray diffraction.

  Further, the thermal conductivity of the insulating substrate and the through metal body was measured by a laser flash method using samples formed individually, and the thermal expansion coefficient was measured in the range of 25 to 400 ° C. by TMA.

Table 3 shows the characteristics and test results of the light-emitting element wiring substrate manufactured through the above steps.

  As shown in Table 3, a sample No. having no penetrating metal body outside the scope of the present invention was used. 20 and 21, since there is no heat dissipation by the through metal body, the heat from the LED chip generated when the light emitting device is energized cannot be sufficiently dissipated, the LED chip exceeds a predetermined temperature, and the LED chip As a result, the light emission efficiency was lowered, and sufficient light emission intensity could not be obtained.

  On the other hand, sample no. In Nos. 1 to 19, excessive heating of the LED chip did not occur, and high luminous efficiency could be realized. Further, the reliability of adhesion between the penetrating metal body and the insulating substrate was sufficient.

  In particular, Sample No. with a frame was formed. In 1-12 and 14-19, the optical characteristic further improved compared with the case where a frame is not provided.

(A) is sectional drawing of the wiring board for light emitting elements of this invention, (b) is sectional drawing of the wiring board for light emitting elements of this invention which provided the frame. These are sectional drawings of the wiring board for light emitting elements of this invention which provided the insulating layer. These are sectional drawings of the wiring board for light emitting elements of this invention which provided the coating layer. (A) is sectional drawing of the light-emitting device of this invention, (b) is sectional drawing of the light-emitting device of this invention which provided the frame. These are sectional drawings for demonstrating the manufacturing method of the wiring board for light emitting elements of this invention. These are sectional drawings for demonstrating the manufacturing method of the wiring board for light emitting elements of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Insulation base | substrate 3 ... Connection terminal 5 ... External electrode terminal 7 ... Penetration conductor 8 ... Penetration metal body 9 ... Mounting part 11 ... Wiring board 13 for light emitting elements -Frame 13a ... Inner wall surface 21 ... Light emitting element 25 ... Light emitting device 31 ... Molding material 40 ... Ceramic green sheet 43 ... Metal sheet 50 ... Composite molded body

Claims (16)

At least a flat insulating substrate made of ceramic fired at a temperature exceeding 1050 ° C., a conductor layer formed on at least one of the surface or the inside of the insulating substrate, and light emission on one main surface of the insulating substrate A wiring board for a light emitting device comprising a mounting portion for mounting an element, wherein a penetrating metal body having a higher thermal conductivity than the insulating substrate and co-fired with the insulating substrate penetrates the insulating substrate. A wiring board for a light-emitting element, characterized by being provided. The light-emitting element wiring board according to claim 1, wherein the through metal body has a cross-sectional area larger than a mounting area of a light-emitting element mounted on the light-emitting element wiring board. The wiring substrate for a light emitting element according to claim 1, wherein the through metal body is a composite containing at least a metal material and a ceramic material. The light-emitting element wiring board according to claim 1, wherein the through metal body forms an electric circuit. The wiring board for a light-emitting element according to claim 1, wherein at least one end face of the through metal body is covered with an insulating film. 6. The light emitting device according to claim 1, wherein the insulating substrate has a thermal conductivity of 30 W / m · K or more and a thermal expansion coefficient of 8.5 × 10 ⁻⁶ / ° C. or more. Device wiring board. The wiring board for a light emitting element according to any one of claims 1 to 6, wherein the insulating base has a three-point bending strength of 350 MPa or more and a total reflectance of 70% or more. The light-emitting element wiring board according to claim 1, wherein the insulating base is made of an MgO-based sintered body having MgO as a main crystal phase. Wherein the insulating substrate is the light emitting element wiring board according to any one of claims 1 to 8, characterized in that of Al ₂ O ₃ quality sintered body of Al ₂ O ₃ as a main crystal phase. The wiring board for a light emitting element according to any one of claims 1 to 9, wherein the conductor layer and the penetrating metal body contain at least one of W, Mo, Cu, and Ag as a main component. The thermal conductivity of the penetrating metal body is 80 W / m · K or more, and the thermal expansion difference Δα with respect to the insulating base is 4 × 10 ⁻⁶ / ° C. or less. The wiring board for light emitting elements as described in 2. The boundary between the insulating substrate and the penetrating metal body formed on the main surface of the wiring board for light emitting elements is covered with a coating layer mainly composed of at least one of metal, ceramics, and resin. The wiring board for light emitting elements according to any one of claims 1 to 11. The frame body for accommodating a light emitting element is formed in the main surface in the side in which the mounting part of the said wiring board for light emitting elements was formed, The Claim 1 thru | or 12 characterized by the above-mentioned. Wiring board for light emitting element. A light emitting device comprising a light emitting element mounted on the mounting portion of the wiring board for a light emitting element according to claim 1. A metal sheet having substantially the same thickness as the ceramic green sheet is formed so as to penetrate the ceramic green sheet, and a composite molded body is manufactured, and the composite molded body is simultaneously fired to penetrate substantially the same thickness as the insulating substrate. And a step of producing an insulating substrate in which the metal body is formed so as to penetrate through the insulating base. Forming a metal sheet having substantially the same thickness as the ceramic green sheet so as to penetrate the ceramic green sheet, and forming the composite molded body and the other composite molded body or other ceramic green sheet. A method of manufacturing a wiring board for a light emitting element, comprising: a composite laminate manufacturing step of stacking at least one of them to prepare a composite laminate, and a step of simultaneously firing the composite laminate.

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