JP2006066519A - Wiring circuit board for light-emitting element and the light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring circuit board for light emitting-element that is excellent in heat radiating property and mounting reliability, and to provide a light-emitting device. <P>SOLUTION: The wiring circuit board for light-emitting element 11 is provided with at least a plate-shaped main body 1, a through hole 2 formed through the body 1, and conductor layers 3, 5, and 7 formed at least either one of the surface and inside of the body 1. The wiring circuit board is also provided with a mounting section 9 for mounting a light-emitting element 21 on one main surface 1a of the body 1. A metallic body 8, having heat conductivity higher than that of the body 1 and a relative density of ≥99.8% with respect to the theoretical specific gravity, is inserted into the through hole 2 formed in the body 1 and jointed to the body 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.

  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, and it is impossible to deal with the problem of heat at all, and there is a problem that the brightness is lowered, it is inexpensive, excellent in heat conduction, and excellent in mounting reliability. The wiring board has not been provided yet.

  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.

  A wiring board for a light emitting element according to the present invention includes at least a flat insulating base, a through hole provided through the insulating base, and a conductor layer formed on at least one of the surface and the inside of the insulating base. And a mounting portion for mounting the light emitting element on one main surface of the insulating base, the wiring board for a light emitting element having a higher thermal conductivity than the insulating base and relative to the theoretical specific gravity. A metal body having a density of 99.8% or more is inserted into a through-hole provided in the insulating base and joined to the insulating base.

  In the light-emitting element wiring board according to the present invention, the insulating base is preferably made of ceramics.

  In the light-emitting element wiring board of the present invention, the insulating base preferably contains a resin.

  In the light-emitting element wiring board of the present invention, it is preferable that the 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 light emitting element wiring board of the present invention, it is desirable that one end face of the metal body is larger than the other end face.

  In the light-emitting element wiring board according to the present invention, it is preferable that an end surface opposite to the mounting portion side of the metal body is larger than an end surface on the mounting portion side of the metal body.

  In the light-emitting element wiring board of the present invention, it is preferable that the insulating base and the metal body are bonded together by a bonding layer.

  Moreover, as for the wiring board for light emitting elements of this invention, it is desirable for the said joining layer to contain a metal.

  Moreover, as for the wiring board for light emitting elements of this invention, it is desirable for the said joining layer to contain resin.

  Moreover, as for the wiring board for light emitting elements of this invention, it is desirable for the said joining layer to contain ceramics.

  In the light-emitting element wiring board of the present invention, it is preferable that the boundary between the insulating base and the metal body formed on the main surface of the light-emitting element wiring board is covered with a coating layer.

  In the light-emitting element wiring board of the present invention, the metal body preferably 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 metal body is covered with an insulating film.

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

  The light-emitting device of the present invention is characterized in that the light-emitting element is mounted on the mounting portion of the wiring board for a light-emitting element described above.

  The wiring board for a light-emitting element of the present invention has a through-hole formed by penetrating a metal body having a relative density with respect to the theoretical specific gravity having a higher thermal conductivity than that of an insulating base to 99.8% or more. The thermal conductivity of the light emitting element wiring substrate can be improved by inserting and bonding to, and the heat generated from the light emitting element can be dissipated more quickly to the outside of the light emitting element wiring substrate. It is possible to prevent the light emitting element from being heated excessively, to prevent a decrease in luminance, or to further increase the luminance. Note that the relative density of 99.8% or more means that there is almost no void, and that the inside does not contain ceramic powder or glass components other than metal, and is a paste used for ordinary wiring boards. This value cannot be obtained by the method of sintering the metal conductor. That is, the present invention uses, for example, a dense metal body that is obtained by processing a metal foil or a metal plate and does not substantially contain components other than metal.

  Further, by using a ceramic having a higher thermal conductivity than the resin as the insulating base, it is possible to further increase the luminance of the light emitting element wiring board.

  Further, according to the present invention, a wiring board for a light-emitting element having practically sufficient heat dissipation can be obtained even when an insulating base formed of a resin having low thermal conductivity is used as compared with ceramics. Obtainable. When the insulating base is formed of an inexpensive resin in this way, the cost of the light emitting element wiring board can be reduced.

  In addition, by making the metal body have a cross-sectional area larger than the mounting area of the light emitting element mounted on the wiring board for the light emitting element, the heat dissipation portion increases, and heat generated from the light emitting element can be quickly dissipated. Can do.

  Also, by making one end surface of the metal body larger than the other end surface, the area of the side surface of the metal body is increased, and the contact area between the insulating substrate and the metal body is increased, so that the insulating substrate and the metal body are Bondability is improved.

  Moreover, by making the end surface on the opposite side to the mounting portion side of the metal body larger than the end surface on the mounting portion side of the metal body, the heat dissipation surface becomes larger and the heat dissipation is improved.

  Moreover, the metal body and the insulating substrate can be easily fixed by bonding the insulating base and the metal body formed on the main surface of the wiring board for light emitting element by the bonding layer.

  When a metal is used as the bonding layer, the heat conduction between the metal body and the insulating base is also improved, so that the heat dissipation of the light emitting element wiring board is further improved.

  Further, when the bonding layer is made of resin, the temperature at the time of bonding is lowered, so that the thermal stress between the metal body and the insulating substrate is reduced, and furthermore, a low-cost wiring board for a light emitting element can be obtained.

  Further, by forming the bonding layer with a chemically stable ceramic, the reliability such as the heat resistance and water resistance of the bonded portion between the metal body and the insulating base is further improved.

  In addition, the generation of cracks at the boundary can be suppressed by covering the boundary between the insulating base and the metal body formed on the main surface of the wiring board for the light emitting element with a coating layer.

  Further, by providing the metal body with a function as an electric circuit, there is no need to separately provide a conduction terminal, and it is possible to achieve both a reduction in the size of the wiring board for the light emitting element, a reduction in the number of manufacturing steps, and a reduction in cost. it can.

  In addition, by covering at least one end face of the metal body with an insulating film, it is possible to prevent a short circuit with an external terminal, and wiring can be arranged directly under the metal body when the light emitting device is mounted on a printed board or the like. Therefore, the device can be miniaturized. 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.

  In addition, by forming a conductor layer and a metal body with at least one of W, Mo, Cu, Ag, and Al as a main component, a wiring for a light-emitting element having higher electrical characteristics and excellent heat dissipation is provided. A substrate can be obtained.

  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 wiring substrate for the light emitting element of the present invention described above, the heat generation from the light emitting element can be quickly discharged outside the device, so that the luminance reduction due to the heat generation is suppressed. it can.

  The light emitting element wiring board of the present invention has, for example, a flat insulating base 1 and a through hole formed so as to penetrate the front and back surfaces of the insulating base 1 as shown in FIGS. 1 (a) and 1 (b). A connection terminal 3 between the hole 2 and the light emitting element formed on the main surface 1 a of the insulating base 1, an external electrode terminal 5 formed on the other main surface 1 b of the insulating base 1, a connection terminal 3 and an external electrode terminal 5 The insulating base 1 is inserted into the through-hole 7 provided through the insulating base 1 so as to be electrically connected to the through-hole 2 provided through the insulating base 1 and joined to the insulating base 1. It is comprised from the metal body 8 with higher heat conductivity.

  And in order to join the insulation base | substrate 1 and the metal body 8, the joining layer 18 containing at least 1 sort (s) chosen from the group of a metal, resin, and ceramics is formed between both.

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

  In addition, for example, in the light emitting element wiring substrate 11 of the present invention, as shown in FIGS. 1A and 1B, a frame 13 for housing a light emitting element to be mounted is provided on the mounting portion 9 side. It is desirable to be formed and configured.

  According to such a light emitting element wiring substrate 11 of the present invention, it is important that the metal body 8 having a higher thermal conductivity than the insulating base 1 is inserted into the through-hole 2 formed in the insulating base 1. In addition, it is particularly important that the relative density of the metal body 8 is 99.8% or more.

  That is, by providing the metal body 8 having a higher thermal conductivity than the insulating base 1, heat generated from the light emitting element mounted on the light emitting element wiring board of the present invention can be quickly dissipated. It is possible to prevent a decrease in luminance.

  In other words, by setting the relative density of the metal body 8 to 99.8% or more, in other words, by using the metal body 8 formed of a solid metal, air bubbles, ceramic powder, glass, and the like are contained inside. Compared with the case of using the contained composite, the thermal conductivity of the metal body 8 can be remarkably increased, and the wiring board 11 for a light-emitting element is further excellent in heat dissipation.

  Such a metal body 8 can be easily obtained by, for example, punching a metal plate made of Cu having a high thermal conductivity, a low resistance, and a relatively low cost, or a metal foil into a desired shape by a press machine. Can be produced.

  The metal body 8 having a complicated shape can be formed by a technique such as pressing, casting, polishing, powder metallurgy, or the like. Needless to say, the metal body 8 may be manufactured by using other conventionally known processing methods.

  Further, as the material of the metal plate 8, in addition to Cu, a composite material such as Al or Cu-W can be used. In the case of using a composite material such as Cu-W containing two or more kinds of metals, the metal body 8 having desired characteristics can be produced by controlling the metal used and its ratio. Of course, the metal body 8 may be made of an alloy. Moreover, the metal body 8 may be configured by combining a plurality of members.

  In addition, it is desirable that the metal body 8 has substantially the same thickness as the insulating base 1 in order to flatten the mounting portion 9 of the light emitting element.

  Such a metal body 8 can be easily obtained at low cost and can be easily attached to various forms of the insulating base 1, so that various forms of the insulating base can be used according to the performance of the mounted light emitting element. 1 can be used to achieve an optimal combination based on performance and cost.

  Further, as shown in FIG. 1A, when the shape of the metal body 8 is such that the side surface of the metal body 8 is parallel to the penetration direction, the metal body 8 is inexpensive.

  On the other hand, as shown in FIG. 1B, when at least a part of the side surface of the metal body 8 is non-parallel to the penetration direction, in other words, the side surface of the metal body 8 When the projections and depressions are provided, the cost of the metal body 8 slightly increases, but the contact area between the insulating base 1 and the metal body 8 increases, so that the bonding strength between the two can be improved. In addition, when providing an unevenness | corrugation in the side surface of the metal body 8, the magnitude | size of the one end surface of the metal body 8 and the other end surface does not need to be different like FIG.1 (b). For example, even if the size of one end surface of the metal body 8 is the same as that of the other end surface, the side surface of the metal body 8 can be provided with irregularities in a range that does not hinder the insertion of the metal body 8. Needless to say.

  Further, as shown in FIG. 1B, the metal body 8 is inserted into the through-hole 2 by forming a flange on the metal body 8 or by making one end face of the metal body 8 larger than the other end face. Since positioning at the time becomes easy, there is an advantage that assemblability is remarkably improved.

  Further, as shown in FIG. 1B, when the area of the end face of the metal body 8 opposite to the mounting portion 9 is increased, the heat transfer path becomes wider, and the heat dissipation of the light emitting element wiring board is further increased. improves. In particular, it is desirable that one end surface of the metal body 8 has an area that is 1.1 times or more that of the other end surface, and more preferably 1.2 times or more.

  Further, for example, the flange portion formed in the metal body 8 may be formed outside the through hole 2.

  In addition, the metal body 8 can be provided with a function as an electric circuit for supplying electricity to a light emitting element to be mounted, for example, and becomes a light emitting element wiring substrate 11 having a small size and excellent heat dissipation. .

  Further, as shown in FIGS. 2A and 2B, by covering at least one end face of the metal body 8 with the insulating film 6, a short circuit with the external terminal 3 or the external electrode terminal 5 can be prevented, As shown in FIG. 2B, the insulating film 6 is formed on the main surface 1b opposite to the light emitting element mounting side of the light emitting element wiring substrate 11, whereby the light emitting device is an external electric circuit board such as a printed board. Since the wiring can be arranged immediately below the metal body 8 when mounted on the device, downsizing of the device can be realized.

  Further, as shown in FIG. 2A, by forming the insulating film 6 on the main surface 1a on the light emitting element mounting side of the light emitting element wiring substrate 11, a short circuit between the electrodes of the light emitting element can be prevented. The flip chip mounting reliability can be improved.

  The insulating film 6 can be easily formed from, for example, a resin used for a solder resist or an insulating resin used for a resin wiring board.

  In particular, in order to make the insulating film 6 excellent in water resistance, it is desirable to contain the ceramic powder in the insulating film 6 at a ratio of 5 to 60% by volume.

  Further, as shown in FIG. 3, even if a crack occurs at the boundary between the insulating base 1 and the metal body 8, the crack can be prevented from progressing to the surface layer of the light emitting element wiring substrate 11. It is desirable to cover the boundary between the insulating substrate 1 and the metal body 8 formed on the main surface of the insulating substrate 1 with, for example, a coating layer 12 mainly composed of a resin. By covering the boundary between the 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.

  Further, an adhesive layer 18 formed between the insulating base 1 and the metal body 8 may be protruded from the through hole 2 so as to close the boundary between the insulating base 1 and the metal body 8. In that case, the covering layer 12 is formed of a material for forming the adhesive layer 18 other than the resin.

Next, the insulating base 1 will be described. For example, a ceramic substrate such as MgO or Al ₂ O ₃ or an organic resin substrate can be suitably used as the insulating base 1 used for the light emitting element wiring substrate 11.

  When a ceramic substrate is used as the insulating substrate 1, it has high performance because it is highly rigid, does not change in quality due to light or heat emitted from the light emitting element, and has a relatively large number of materials with relatively high thermal conductivity. The light-emitting element wiring substrate 11 has a long life.

In addition, when a low-temperature fired substrate, so-called glass ceramics, is used as the insulating substrate 1, the thermal conductivity, strength, and rigidity are not limited to ceramics fired in a temperature range of 1050 ° C. or higher such as Al ₂ O _3. Although it is inferior, since the thermal expansion coefficient can be easily controlled, it is possible to easily match the thermal expansion coefficient with the metal body 8. Further, since low resistance Cu, Ag, or the like can be simultaneously fired as the wiring layer, electrical loss and heat generation in portions other than the light emitting element can be suppressed.

  Moreover, when resin is used as the insulating substrate 1, an inexpensive light emitting element wiring substrate 11 is obtained. In order to improve the rigidity, strength, hygroscopicity, and heat resistance of the insulating substrate 1, it is desirable to use a ceramic substrate or a resin substrate containing glass cloth.

  The materials used as these insulating bases 1 will be described in detail below.

For example, the insulating substrate 1 having MgO as the main crystal is, for example, an MgO powder having an average particle diameter of 0.1 to 8 μm and a purity of 99% or more, Y ₂ O ₃ or Yb ₂ O having an average particle diameter of 0.1 to 8 μm. rare earth oxides such as _{3, Al 2 O 3, SiO} 2, CaO, SrO, BaO, and _B 2 O 3, the molded body obtained by adding at least one sintering aid selected from the group consisting of ZrO ₂ 1300 to It is obtained by firing in a temperature range of 1700 ° C.

Alternatively, MgAl ₂ O ₄ containing MgO or MgO · SiO ₂ based composite oxide may be added. 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 in order to obtain a dense body having MgO as the main crystal. 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.

  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.

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.

Such an Al ₂ O ₃ sintered body has, for example, an average particle size of 0.1 to 8 μm, preferably 1.0 to 2.0 μm and an Al ₂ O ₃ powder with a purity of 99% or more and an average particle size of 1 Firing a molded body to which at least one kind of sintering aid selected from the group of Mn ₂ O ₃ , SiO ₂ , MgO, SrO, and CaO of 0 to 2.0 μm is added in a temperature range of 1300 to 1500 ° C. Is obtained.

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.

To such a composition containing MgO or Al ₂ O ₃ as a main component, a binder and a solvent are further added to prepare a slurry. For example, a sheet-like molded body is prepared by a doctor blade method, Then, after printing and filling a conductive paste containing at least a metal powder on the surface or through holes provided in the sheet-like molded body, the sheet is laminated and then laminated in an oxidizing atmosphere, a reducing atmosphere, or an inert atmosphere. By firing, the insulating base body 1 in which wiring layers such as the connection terminals 3, the external electrode terminals 5, and the through conductors 7 are formed on the surface or inside can be manufactured. 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.

  Needless to say, it is necessary to previously form a hole to be the through hole 2 for inserting the metal body 8 in the sheet-like molded body before the firing step.

  Further, even when a low-temperature fired substrate is used as the insulating substrate 1, the insulating substrate 1 provided with the through-holes 2 and the wiring layer is basically manufactured in the same manner, although the materials and the firing temperature are different. Can do.

  Further, when a resin is used as the insulating substrate 1, it is desirable to use a glass-epoxy substrate used for a conventionally known printed wiring board or the like. On the glass-epoxy substrate, the connection terminal 3, the external electrode terminal 5, and the through conductor 7 are formed by a normal method for manufacturing a printed wiring board, and further, a through hole for forming the metal body 8 is drilled, laser Etc.

  Next, a metal body 8 having a relative density with respect to the theoretical specific gravity of 99.8% or more is prepared for the various insulating bases 1 provided with the through holes 2 described above, and the metal body 8 is inserted into the through holes 2. Thus, the insulating substrate 1 and the metal body 8 can be bonded together by the bonding layer to obtain the light emitting element wiring substrate 11.

  As the bonding layer 18 used here, an adhesive made of metal, ceramics, resin, or a composite is suitably used.

  When a metal is used for the bonding layer 18, the process can be simplified by using a low melting point metal such as solder. Examples of the solder used include conventionally known tin 60 to 10% -lead 40 to 90% and lead-free solder containing no lead.

  When solder is used, the insulating substrate 1 and the metal body 8 can be joined by processing in a reflow furnace in a nitrogen atmosphere under conditions of 230 ° C. × 10 seconds.

  In addition to solder, an active metal can be used to join the insulating substrate 1 and the metal body 8 by a so-called active metal method.

  When a metal is used as the bonding layer 18, it is necessary to form a metal layer on the inner wall of the through hole 2 in order to improve wettability with the bonding layer 18.

  Further, when a resin is used as the bonding layer 18, it is desirable to use a generally used epoxy resin-based bonding agent.

  And according to the curing temperature of each bonding agent, for example, the bonding agent is cured under conditions of 80 to 150 ° C. and 20 to 40 minutes, and the insulating base 1 and the metal body 8 are bonded via the bonding layer 18. be able to.

  Bonding using this resin is excellent in that it is inexpensive and easy. In particular, when combined with the insulating base 1 made of resin, the bonding strength becomes high and processing at a relatively low temperature is possible, so there is almost no damage to the insulating base 1 and there is no crack at the interface. A highly reliable wiring board 11 for a light emitting element can be manufactured.

  Moreover, as a case where ceramics are used as the bonding layer 18, for example, a glass having a low melting point can be exemplified. By using such a low-melting glass, bonding at a relatively low temperature (600 ° C. or less) is possible, and the stress generated by the bonding can be reduced.

  Needless to say, the bonding layer 18 may be a composite of metal, ceramics, and resin. For example, the thermal expansion coefficient of the bonding layer can be controlled by mixing metal powder, ceramic powder, and resin, and bonding according to the characteristics of the insulating substrate 1 can be performed.

  By forming the conductor and metal body 8 used in the wiring circuit formed on the light emitting element wiring substrate 11 as a main component of at least one of W, Mo, Cu, Ag, and Al, the electrical characteristics, An inexpensive light-emitting element wiring substrate 11 having excellent heat dissipation can be obtained.

  Further, by applying Al plating or Ag plating to the surfaces of the connection terminal 3 and the metal body 8, the resistance to corrosion is improved, the reliability of the wiring board 11 for the light emitting element is improved, and the connection terminal 3 and the metal body are improved. The reflectance of 8 can be improved.

  It is desirable to provide a frame 13 on the main surface of the light emitting element wiring substrate 11 on the mounting portion 9 side. For example, when the insulating base 1 made of ceramics is used, the frame 13 is made of ceramics. By forming, the insulating base 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 can be easily manufactured.

  Further, since ceramics are excellent in heat resistance and moisture resistance, a wiring board for a light emitting device having excellent durability even when used for a long period of time or under adverse conditions by using a ceramic frame 13. 11

  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, Al or the like may be formed on the inner wall surface 13a of the frame 13 in order to improve the reflectance.

  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. -Brazing via a brazing material (not shown) made of Cu brazing material or the like, or joining by soldering can be performed.

  Needless to say, a resin-based adhesive may be used, and the same material as the resin-based bonding layer 18 can be used.

  Then, for example, as shown in FIGS. 4A and 4B, 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 bonding wire 23 emits light. By electrically connecting the element 21 and the connection terminal 3 and supplying power to the light emitting element 21, the light emitting element 21 can function, and heat generated from the light emitting element 21 can be quickly emitted from the metal body 8. Therefore, a heat radiating member such as a heat sink is not necessary, and it is possible to contribute to downsizing of an electric device to be mounted, and the inexpensive light emitting device 25 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. In addition, since the metal body 8 has a high thermal conductivity, heat generated from the light emitting element 21 can be quickly released, and a reduction in luminance due to heat generation can be suppressed.

  4A and 4B, in the light emitting device 25 in which the frame 13 is mounted on the main surface 1a of the light emitting element wiring substrate 11 on the side where the light emitting element 21 is mounted, the frame 13 By storing the light emitting element 21 inside 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 by the bonding agent 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 addition, as a cover body, it is desirable to use translucent materials, 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.

  Moreover, in the example demonstrated above, although the form which provided the frame 13 was demonstrated, it cannot be overemphasized that the form which does not comprise the frame 13 may be sufficient.

Using MgO powder with a purity of 99% or more and an average particle diameter of 1 μm, and Y ₂ O ₃ powder with a purity of 99% or more and an average particle diameter of 1 μm as a raw material powder for an insulating substrate of a wiring board for a light emitting device, 95% by mass of MgO powder The raw material powder was mixed at a ratio of 5% by mass of Y ₂ O ₃ , 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 was prepared by a doctor blade method.

Further, using W and Cu powder having an average particle diameter of ₂ μm and Al ₂ O ₃ having an average particle diameter of 1.0 μm, the metal powder and the acrylic system at a ratio of W 50 mass%, Cu 50 mass%, and Al ₂ O ₃ 5 mass% A binder and acetone were mixed as a solvent to prepare a conductor paste.

  The ceramic green sheet is punched to form a via hole having a diameter of 100 μm for forming a through conductor, and the via hole is filled with a conductive paste by a screen printing method. Was printed and applied. In addition, a through hole for inserting a metal body was formed together with a via hole during punching.

  The green sheets thus produced were combined, aligned, laminated and pressure-bonded, and a laminate having dimensions after firing of 10 mm × 10 mm × 0.6 mm in thickness was produced.

  In addition, this laminated body produced three types, the thing which does not provide a frame, the thing which provides a ceramic frame, and the thing which provides a metal frame.

  For the ceramic frame body, the mounting portion side on which the light emitting element of the laminated body is mounted has an outer dimension of 10 mm × 10 mm × 2 mm, and the inner diameter on the side in contact with the laminated body is 4 mm. A frame made of the same material as that of the insulating substrate having a tapered through hole with an inner diameter of 8 mm on the side was formed. In addition, the molded object used as this frame was formed as an integral body by thermocompression bonding with the laminate.

  Moreover, about what provides a metal frame, the metal paste was screen-printed in the part which contact | connects the frame by the side of the mounting part of a laminated body, and the metal layer was formed.

  And after degreasing the laminated body integrated with the molded body to be a frame body at 900 ° C. in a nitrogen-hydrogen mixed atmosphere at a dew point of + 25 ° C., it is shown in Table 1 in a nitrogen-hydrogen mixed atmosphere at a dew point of + 25 ° C. It was fired by holding at the maximum temperature for 2 hours.

Thereafter, Ni and Au 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.

Next, for a sample provided with 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 is used to form a frame using solder. Was bonded to an insulating substrate.

  As shown in Table 2 and FIG. 5, the through holes for inserting the metal body are formed in two types of shapes, in which the wall surface of the through holes is provided with irregularities and stepped, and in which no irregularities are provided. It was processed into.

Next, a metal body having a shape such that a gap of 50 μm was formed between the metal body and the through hole when the metal body was inserted into the inner wall of the through hole was prepared. The metal body was processed so that its thickness was substantially the same as that of the insulating base. In addition, although the composition of the metal body used in Table 2 is shown, a solid metal body having a purity of 99% or more is used for those using a single metal element. Moreover, about the metal body described as Cu-W, the composition of Cu 20 mass% and W mass 80% was used. Table 2 shows the relative density, thermal expansion coefficient, and thermal conductivity of the metal body. The thermal expansion coefficient of the insulating substrate after firing was 10 × 10 ⁻⁶ / ° C. In addition, the measurement of the thermal expansion coefficient was performed in the temperature range of 25-400 degreeC using TMA.

  Next, an epoxy resin adhesive was applied to the surface of the metal body with a dispenser, and the metal body coated with the epoxy resin adhesive was inserted into the through hole of the insulating substrate. Thereafter, the adhesive was cured at 120 ° C. for 30 minutes to bond the metal body and the insulating substrate to obtain a wiring board for a light emitting element.

Further, an epoxy resin adhesive is applied to the mounting portion of the wiring board for these light emitting elements using a dispenser, an LED chip which is a light emitting element with an output of 1.5 W is mounted, and the LED chip and the connection terminals are connected by bonding wires. Then, the LED chip and the connection terminal were covered with a molding material made of an epoxy resin having a thermal expansion coefficient of 40 × 10 ⁻⁶ / ° C. to obtain a light emitting device.

  Using the obtained light emitting device, a temperature cycle test of −55 ° C. to 125 ° C. was performed 1000 cycles, and after the test, the peeling state of the bonding interface between the 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.

  Further, as a comparative example, in place of the step of inserting and joining the metal body into the through hole, the step of filling the through hole for inserting the metal body formed together with the via hole with the conductive paste, the laminate and the through hole A step of co-firing the filled conductor paste was performed to produce a wiring board for a light emitting element on which a metal body having a relative density of less than 99.8% was formed, and the same test as in the example was performed.

  As for the relative density of the metal body of the comparative example, the ratio of voids and ceramic powder clearly exceeds 0.2% by cross-sectional SEM observation of this metal body, although the exact value is not certain. The content of less than 99.8% was not debatable, and the metal body was judged to be less than 99.8% by cross-sectional SEM observation.

Al ₂ O ₃ powder having a purity of 99% or more and an average particle size of 1.0 μm as a raw material powder, Mn ₂ O ₃ powder having a purity of 99% or more and an average particle size of 1.3 μm, a purity of 99% or more, an average particle size of 1. using SiO ₂ powder 0 .mu.m, _Al 2 _{O 3} powder 90 wt%, _Mn 2 _{O 3} powder 5% by weight, mixing the raw material powder at a ratio of SiO ₂ powder 5% by weight, as molding organic resin (binder) An acrylic binder and toluene were mixed as a solvent to prepare a slurry. Thereafter, a ceramic green sheet was prepared by a doctor blade method.

  The conductor paste was prepared by using the same raw material as that used when MgO was the main component and adjusting the same process at the same rate.

  The ceramic green sheet is punched to form a via hole having a diameter of 100 μm for forming a through conductor, and the via hole is filled with a conductive paste by a screen printing method. Was printed and applied. In addition, a through hole for inserting a metal body was formed together with a via hole during punching.

  The green sheets thus produced were combined, aligned, laminated and pressure-bonded, and a laminate having dimensions after firing of 10 mm × 10 mm × 0.6 mm in thickness was produced.

  And after performing degreasing | defatting at 900 degreeC in nitrogen-hydrogen mixed atmosphere with dew point +25 degreeC, it continued and baked by hold | maintaining at the maximum temperature shown in Table 1 for 2 hours in nitrogen-hydrogen mixed atmosphere with dew point +25 degreeC.

  Thereafter, Ni and Au plating were sequentially applied to the surfaces of the connection terminal and the external electrode terminal.

In Example 2, a metal frame was used. As the material of the frame used, an Al metal frame having a thermal expansion coefficient of 23 × 10 ⁻⁶ / ° C. and a thermal conductivity of 238 W / m · K was used. In addition, for the metal frame, a conductive paste that forms connection terminals and external electrode terminals is used to form a metal layer on the portion where the frame on the mounting portion side of the insulating base is mounted, and then solder is used. The frame body was bonded to an insulating substrate.

Moreover, the material shown in Table 2 was used also about the metal body similarly to the case where MgO is the main component. Then, in the same process as in Example 1, the insulating substrate and the metal body were joined with an epoxy resin adhesive to obtain a wiring board for a light emitting element. Table 2 shows the thermal expansion coefficient of the metal body. The thermal expansion coefficient of the insulating substrate was 7.5 × 10 ⁻⁶ .

An epoxy resin as a bonding agent is applied to these light emitting element wiring boards using a dispenser, an LED chip that is a light emitting element with an output of 1.5 W is mounted on the mounting portion, and the LED chip and the connection terminal are connected by a bonding wire. Further, the LED chip and the connection terminal were covered with a molding 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 bonding interface between the 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.

When using a resin as the insulating substrate, first, a copper-clad substrate in which a copper foil is formed on both sides of a printed wiring board having a thermal expansion coefficient of 16 × 10 ⁻⁶ / ° C. and a thickness of 0.6 mm made of a glass-epoxy substrate. Were used to form connection terminals, external electrode terminals, through conductors, and through holes by a conventionally known subtractive method. The through conductor was formed by copper plating. A copper plating layer was also formed on the inner wall of the through hole. The glass-epoxy substrate had a thermal expansion coefficient of 16 × 10 ⁻⁶ / ° C.

Further, a metal frame was used as the frame, and an Al metal frame having a thermal expansion coefficient of 23 × 10 ⁻⁶ / ° C. and a thermal conductivity of 238 W / m · K was used. In addition, for a light emitting element wiring board provided with a metal frame, a copper layer is used to form a connection terminal and an external electrode terminal. After forming the frame, the frame was joined to the insulating substrate using solder. As the solder, conventionally known tin 40% -lead 60% was used, and the frame and the insulating substrate were joined to a reflow furnace in a nitrogen atmosphere at 230 ° C. for 10 seconds.

  Next, a metal body having such a shape that a gap of 50 μm was formed between the metal body and the through hole when the metal body was inserted into the inner wall of the through hole was prepared. The metal body was processed so that its thickness was substantially the same as that of the insulating base. In addition, although the composition of the metal body used in Table 2 is shown, a solid metal body having a purity of 99% or more is used for those using a single metal element. Moreover, about the metal body described as Cu-W, the composition of 20 mass% of Cu and 80 mass% of W was used. Table 2 shows the relative density, thermal expansion coefficient, and thermal conductivity of this metal body. After inserting this metal body into the through hole, the solder paste was filled in the gap with a dispenser, and the metal body and the insulating substrate were joined to a reflow furnace in a nitrogen atmosphere at 230 ° C. × 10 seconds. The solder used heretofore known tin 40% -lead 60%. Moreover, it shows in Table 2 about the thermal expansion coefficient of a metal body.

Epoxy resin as a bonding agent is applied to these light-emitting element wiring boards using a dispenser, LED chips that are light-emitting elements with an output of 1.5 W are mounted on the mounting portion, and the LED chips and connection terminals are connected by bonding wires. Further, the LED chip and the connection terminal were covered with a molding 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 bonding interface between the 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.

Table 2 shows the characteristics and test results of the light-emitting element wiring substrate manufactured through the above steps.

  As shown in Table 2, the sample Nos. With a relative density of the metal body of less than 99.8% and outside the scope of the present invention. 1, sample No. 1 of the present invention using a metal body having the same shape and a relative density exceeding 99.8%. It can be seen that the thermal conductivity of the metal body is lower than 2, and the heat dissipation and optical characteristics of the wiring board for a light emitting element are poor.

  On the other hand, Sample No. which is a wiring board for a light emitting element of the present invention. Nos. 2 to 26 are affected by the thermal conductivity of the insulating substrate, but by using a dense metal body that eliminates the factors that hinder thermal conduction such as voids and ceramic powder, excellent heat dissipation and optical characteristics can be obtained. It became the wiring board for light emitting elements which has.

These are sectional drawings of the wiring board for light emitting elements of this invention. These are sectional drawings of the wiring board for light emitting elements of this invention which provided the coating film. These are sectional drawings of the wiring board for light emitting elements of this invention which provided the coating layer. These are sectional views of the light-emitting device of the present invention. These are sectional drawings which show the shape of a metal body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Insulation base | substrate 2 ... Through-hole 3 ... Connection terminal 5 ... External electrode terminal 6 ... Insulating film 7 ... Through-conductor 8 ... Metal body 9 ... Mounting part 11 ..Light-emitting element wiring board 12 ..Coating layer 13 ..Frame body 13a ..Inner wall surface 17 of frame body ... Metal layer 18 ... Junction layer 21 ... Light-emitting element 23 ... Wire bond 25 ... Light emitting device 29 ... Binder 31 ... Mold material

Claims (16)

At least a flat insulating base, a through hole provided through the insulating base, a conductor layer formed on at least one of the surface and the inside of the insulating base, and one main surface of the insulating base A metal substrate having a higher thermal conductivity than the insulating base and having a relative density with respect to the theoretical specific gravity of 99.8% or more. Is inserted into a through-hole provided in the insulating base and bonded to the insulating base. The light-emitting element wiring board according to claim 1, wherein the insulating base is made of ceramics. The light-emitting element wiring board according to claim 1, wherein the insulating substrate contains a resin. The light emitting element wiring board according to any one of claims 1 to 3, wherein the 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. 5. The wiring board for a light emitting element according to claim 1, wherein one end face of the metal body is larger than the other end face. 6. The wiring board for a light emitting element according to claim 1, wherein an end surface opposite to the mounting portion side of the metal body is larger than an end surface on the mounting portion side of the metal body. The light-emitting element wiring board according to claim 1, wherein the insulating base and the metal body are bonded together by a bonding layer. The light-emitting element wiring board according to claim 7, wherein the bonding layer contains a metal. The light-emitting element wiring board according to claim 7, wherein the bonding layer contains a resin. The light-emitting element wiring board according to claim 7, wherein the bonding layer contains ceramics. The light emitting element according to claim 1, wherein a boundary between the insulating base and the metal body formed on a main surface of the wiring board for the light emitting element is covered with a coating layer. Wiring board. The light emitting element wiring board according to claim 1, wherein the metal body forms an electric circuit. The light emitting element wiring board according to claim 1, wherein at least one end face of the metal body is covered with an insulating film. The light-emitting element wiring board according to claim 1, wherein the conductor layer and the metal body contain at least one of W, Mo, Cu, Ag, and Al as a main component. The frame body for accommodating a light emitting element is formed in the main surface at the side in which the mounting part of the said wiring board for light emitting elements was formed, The Claim 1 thru | or 14 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.

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