JPH09293904A - Led package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an LED device to deteriorate less in emission output and to be increased in mounting reliability when it is mounted on a feeder circuit board, by soldering by a method wherein the light emission peak of the LED device is set lower in wavelength than a specific value, the surface of a dielectric layer is covered with a silver-while precious metal, and the surface of an electrode terminal is coated with Au. SOLUTION: A conductor layer 14 which feeds an electric power to the electrode 13 of an LED device 12 is formed on the surface of a support member 11, and an electrode terminal 15 where an electric power is fed from an external feeder circuit board is provided to the rear of the support member 11 and connected to the conductor layer 14 with an electrical connector 16. The surface of the conductor layer 14 is coated with silver-white precious metal, and the surface of the electrode terminal 15 is covered with Au. The emission light peak of the LED device 12 is set shorter than 600nm in wavelength. By this setup, light emitted from an LED device of emission peak wavelength 600nm can be reflected, and the LED device which is soldered high in strength to a feeder circuit board and high in efficiency and output power can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED package which supports an LED and supplies electric power, and more particularly to an LED package which is excellent in light emission output.

[0002]

2. Description of the Related Art LEDs are used in flat displays such as signboards and advertising towers. LED display has
It is known that an LED chip is placed on a substrate, electrodes are connected to the substrate, and the resin is molded. For example, LE is directly mounted on the substrate.
Direct bonding type for mounting D element (bare chip) or chip type L as shown in FIG.
There is one in which the ED is surface-mounted on the substrate. These LEDs
The display needs an LED package for supporting the LED element and supplying electric power to light the LED element.

Conventionally, in the LED package, the conductor portions of the conductor layer 14 and the electrode terminals 15 are uniformly coated with a noble metal such as Au or Ag. This was mainly intended to prevent oxidation of the conductor portion.

The electrode terminals 15 are usually soldered in order to make an electrical connection with a power supply circuit. Therefore, in order to obtain a strong soldering strength, it was necessary to coat the electrode terminals 15 with Au having good solder wettability in order to improve the reliability of mounting.

To coat the conductor portion with Au, an electroplating method is usually applied, and the conductor layer 14 connected to the electrode 13 of the LED element 12 is also Au-plated at the same time. However, if the conductor layer 14 is plated with Au, the L
When the emission color of the ED element 12 is blue, blue green, or green, there is a drawback that the emission output is reduced. Especially blue LED
In the case of, the output is reduced by about 30%. This is Au
This is because the coating (1) does not have a uniform reflectance in the entire visible range, and in particular, has a reddish body color that absorbs blue, blue-green, or green light emission. Table 1 shows the spectral reflectance of Au. From this table, the reflectance is 60
It is 91.9% or more at 0 nm or more, and most of the light is reflected, but at wavelengths less than this, the absorption is large and 50
At 0 nm, the reflectance is 50% or less, which means that
Indicates that light having a wavelength shorter than that of yellow is largely absorbed.

[0006]

[Table 1]

Therefore, when Ag, which is generally used as a silver-white noble metal, is plated on the entire surface of the conductor portion consisting of the conductor layer 14 and the electrode terminal 15, blue, blue-green, and green light emission from the LED is absorbed. However, there is almost no reflection, and there is no reduction in light emission output as in the case of using Au. However, A
g has poor solder wettability, and when Ag is coated on the electrode terminal 15, the soldering strength to the power supply circuit is weakened, and the reliability of mounting on the power supply circuit board deteriorates.

[0008]

SUMMARY OF THE INVENTION Therefore, the present invention has been made in view of the above circumstances, and when a blue, blue-green or green light emitting LED chip is mounted, a decrease in light emission output is small, and It is an object of the present invention to provide an LED package having high reliability of mounting by soldering to a power supply circuit board.

[0009]

Means for Solving the Problems The present inventor can solve the problem by selectively coating different kinds of precious metals on the surface of a conductor layer formed on a ceramics LED package and the surfaces of electrode terminals. The present invention has been solved and the present invention has been solved.

That is, the LED package of the present invention is
An LED package in which a conductor layer for supplying electric power to the electrodes of the LED elements is provided on the surface of the supporting member and an electrode terminal for supplying electric power from the outside is provided on the rear surface of the supporting member, and the electrode terminals are electrically connected to the conductor layer. The light emitting peak wavelength of the LED element is 600 nm or less, the surface of the conductor layer is coated with a silver-white noble metal, and the surface of the electrode terminal is coated with Au.

The LED package of the present invention is LE
In the LED package having a structure in which the electrode of the D element and the conductor layer are electrically connected by an Au wire, the conductor layer is covered with Ag.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An LED package of the present invention will be described with reference to FIG. An electric conductor layer 14 capable of supplying electric power to the electrode 13 of the LED element 12 is formed on the front surface of the supporting member 11, and an electrode terminal 15 to which electric power is supplied from an external power supply circuit board is formed on the rear surface of the supporting member 11, and the electrode The terminal 15 is connected to the conductor layer 14 by the electrical connection portion 16.
The surface of the conductor layer 14 is coated with a silver-white noble metal, and the surface of the electrode terminal 15 is coated with Au. The emission peak wavelength of the LED element shown in FIG. 1 is 600.
nm or less.

The support member is used for arranging and electrically connecting the LED element at a desired place, and may be a chip type LED substrate as shown in FIG. 1 or the LED element. A direct bonding type module substrate in which a large number are mounted in a matrix may be used. It is preferable that the material has high mechanical strength and little thermal deformation. Specifically, a printed circuit board made of ceramics, glass, an aluminum alloy or the like, or plastic can be used.

The LED element that emits light having an emission peak wavelength of 600 nm or less is not particularly limited by its composition. GaAlN, Zn on the substrate by the liquid layer growth method or the MOCVD method.
S, ZnSe, SiC, GaP, GaAlAs, AlI
A material in which a semiconductor such as nGaP, InGaN, GaN, or AlInGaN is formed as a light emitting layer is used.

Noble metals include gold (Au), silver (Ag), and platinum group elements ruthenium (Re) and rhodium (R).
h), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt), and alloys thereof may be used. A silver-white noble metal is silver (A
g) and platinum group elements, and may be alloys thereof.

The electrode 1 of the LED element 12 as shown in FIG.
In the LED package having a structure in which 3 and the conductor layer 14 are electrically connected by the Au wire 17, it is preferable that the conductor layer is covered with Ag among the silver-white noble metals. It has a melting point of 962 ° C. for Ag and 10 for the melting point of Au.
Since it is close to 64 ° C., both metals are melted at the time of wire bonding, and ideal fusion occurs, so that strong wire bonding can be obtained and an LED having almost no Au wire peeling defect can be obtained. . In addition, since Ag is a silver-white noble metal, Ag is coated on the conductor layer, so that blue, blue-green, and green light emitted from the LED element can be efficiently reflected.

The present invention also provides an LED as shown in FIG.
Sufficient for flip-chip connection in which the pair of electrodes 23 of the element 22 and the Ag-covered conductor layer 24 provided on the surface of the support member 21 are opposed to each other and are connected via the conductive brazing material 27. Is effective for. In this case, since fusion is not necessary, even if Ag is not coated on the conductor layer, a high reflection effect can be expected if it is another silver-white noble metal. The electrode terminal 25 is connected to a power supply circuit and supplies electric power to the conductor layer 24 via the electrical connection portion 26.

[0018]

EXAMPLE An LED package in which the supporting member is a ceramic containing alumina as a main component, the surface of the conductor layer is covered with Ag, and the surfaces of the electrode terminals are covered with Au will be described as an example.

A solvent, a dispersant, a binder, and a plasticizer were added to alumina powder to form a slurry, and the alumina slurry was discharged by a doctor blade method and dried to obtain a green sheet. In order to form an electrical connection that connects the conductor prints on both sides of the green sheet, a through hole is opened according to a conventional method, a tungsten paste is printed on both sides by screen printing, and finally the surface of the LED package shown in FIG. 3 is printed. A portion 34 to be a conductor layer,
A portion 35 to be an electrode terminal and a portion 36 to be an electrical connection portion were formed on the back surface. Next, in order to form the partition walls 38 that form the cavities 39, a green sheet having holes formed in a matrix shape was stacked on the conductor layer side and pressed. Next, the green sheet is dried, degreased,
By sintering, a ceramic substrate having a tungsten conductor wiring formed was obtained.

In the first step of coating the noble metal, the portion 34 which becomes the conductor layer and the portion 35 which becomes the electrode terminal are Au-plated at the same time. Au plating was performed as follows. Degrease the ceramics substrate, etch tungsten wiring, acid activation, strike Ni plating, bright Ni plating, acid activation,
Strike Au plating and bright Au plating are performed in this order, and are dried to form a conductor layer portion 34 and an electrode terminal portion 3.
5 was Au plated.

In the second step of the noble metal coating, the portion 35 to be the Au-plated electrode terminal is entirely masked with resin,
The unmasked portion was plated with Ag. By immersing only the side of the substrate where the electrode terminal portion 35 is formed in resin, pulling it up and drying it,
A ceramic substrate having a resin mask only on the electrode terminal side is obtained. By using this mask, the portion 35 that becomes the electrode terminal is not Ag-plated, and the portion that becomes the conductor layer 3
Only 4 is Ag plated selectively. Acid activation of ceramics substrate, strike Ni plating, bright Ni plating,
The acid activation, the strike Ag plating, and the bright Ag plating were performed in this order, followed by drying, and the portion 34 to be the conductor layer was plated with Ag.

When a resin mask is taken, Ag plating is applied to the surface of the portion 34 which becomes the conductor layer, and the portion 35 which becomes the electrode terminal.
As a result, a ceramics substrate whose surface was plated with Au was obtained.

A nitride-based high-intensity blue LED element is adhered to the obtained ceramic substrate, and the electrode of the LED element and A
A portion 34 which becomes a conductor layer plated with g was wire-bonded with an Au wire. By indexing the obtained ceramic substrate into units of each cavity 39, a chip type LED as shown in FIG. 1 was obtained.

A driving voltage Vf is applied to the chip type LED element.
= 3.6v, electric current of 20mA was supplied, and the relative light emission output of the LED at a wavelength of 450nm was measured. Also,
The solder wettability of the electrode terminals of the LED package was measured by a method of measuring the soldering strength of the electrode terminals as a relative position of the force required for removing the solder. The results are summarized in Table 1.

[Comparative Example 1] After the Au plating obtained in the first step, a high brightness blue LED element of a nitride type is adhered to the portion 35 which will become an electrode terminal without plating Ag, and LE
Portion 3 to be the electrode of D element and the conductor layer plated with Au
4 was wire-bonded with Au wire. A chip-type LED was obtained by indexing the obtained ceramic substrate into units of each cavity 39. In the obtained chip-type LED, both the conductor layer 14 shown in FIG. 1 and the electrode terminals 15 are plated with Au. The emission output and solder wettability of this chip-type LED were measured by the same method as in Example 1, and the results are summarized in Table 1.

[Comparative Example 2] The Au plating in the first step was omitted, the ceramic substrate was degreased, and the second step was carried out to plate Ag on the portions 34 to be the conductor layer and the electrode terminals. A nitride-based high-intensity blue LED element was adhered to this, and the electrode of the LED element and the portion 34 to be the Ag-plated conductor layer were wire-bonded with an Au wire. A chip-type LED was obtained by indexing the obtained ceramic substrate into units of each cavity 39. In the obtained chip type LED, both the conductor wiring 14 shown in FIG. 1 and the electrode terminal 15 are plated with Ag. The emission output and solder wettability of this chip type LED were measured by the same method as in Example 1, and the results are summarized in Table 2.

[0027]

[Table 2]

From Table 2, the chip-type LED using the LED package of the embodiment of the present invention has a high relative light emission output at a wavelength of 450 nm, and the wettability of the solder of the electrode terminals on the back surface of the LED package is high. It is possible to provide a highly reliable chip-type LED that can be mounted at high density.

[0029]

As described above, in the LED package of the present invention, a silver-white noble metal coating is applied to the conductor layer on the surface of the supporting member to supply electric power to the electrodes of the LED element, and the outer surface of the rear surface of the supporting member is covered. To the electrode terminals that are powered by
The emission peak wavelength is 60 by selectively coating.
It is possible to sufficiently reflect the light emitted from the LED having a wavelength of 0 nm or less, and to obtain the LED having the high soldering strength to the power supply circuit board, the high efficiency, and the high light emission output.

Further, in an LED package having a structure in which the electrode of the LED chip and the conductor layer are electrically connected by an Au wire, Ag is used as the silver-white noble metal of the conductor layer.
Is most preferably used. This is because the melting point of Au and the melting point of Ag of the conductor layer are close to each other, so that complete fusion occurs and defects due to peeling of the Au wire are reduced.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a chip type LED in which an LED element is mounted on an LED package.

FIG. 2 is a schematic sectional view of a chip-type LED in which an LED element is mounted on an LED package.

FIG. 3 is a schematic cross-sectional view showing one manufacturing process of coating an LED package with a noble metal.

[Explanation of symbols]

 11, 21 ... Support member 12, 22 LED element 13, 23 ... Electrode 14, 24 ... Conductor layer 15 ... .... Electrode terminals 16, 26 ... Electrical connection 17 ... Au wire 18, 38 ... Partition wall 19, 39 ... Cavity 27 ..... Conductive brazing material 34 ..... Part that becomes conductor layer 35 ..... ..... Parts that become electrical connection parts

Claims (2)

[Claims] 1. A support member front surface is provided with a conductor layer for supplying electric power to an electrode of an LED element, and a support member rear surface is provided with an electrode terminal for external power supply, and the electrode terminal is electrically connected to the conductor layer. The LED package
An LED package, wherein the ED element has an emission peak wavelength of 600 nm or less, the surface of the conductor layer is coated with a silver-white noble metal, and the surface of the electrode terminal is coated with Au. 2. The electrode of the LED element and the conductor layer are made of Au.
The LED package according to claim 1, wherein the conductor layer is covered with Ag in an LED package having a structure electrically connected by a wire.