JPH10303464A - Smd-type led - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the heat generation of an LED and materialize high- brightness light emission by radiating heat, even in case that a large current is let flow to an LED. SOLUTION: This LED is provided with a pair of opposed top electrodes 2 at the top ends of an insulating substrate 1, and for the pair of the top electrodes 2, a bottom electrode 3 at the rear and a side electrode 4 leading to the top electrode 2 and the bottom electrode 3 at the side are made each. In the region which includes the die bond area 9 and its periphery on one top electrode 2a, a heat radiating plate 10 consisting of conductive member is fixed by a fixing means such as a conductive adhesive 11 or the like, an LED element 5 is mounted on the heat radiating plate 10, and a bonding wire 6 is connected to the other top electrode 2b sealed with sealing resin 7. Since it radiates heat even if a large current (about 300 mA or over) is let flow, it prevents the heat generation of the LED, and high-brightness light emission can be materialized. The high-brightness LED becomes inexpensive, and this can be mounted on a high-brightness target product which is not used up to now.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-luminance SMD.
Type LED.

[0002]

2. Description of the Related Art In recent years, electronic devices have been pursuing high performance and multiple functions, as well as miniaturization and weight reduction. Therefore, electronic components are often mounted on a printed circuit board and sealed with a resin. Many of the SMD parts have a substantially parallelepiped shape,
It is connected to the wiring pattern on the printed board by a fixing means such as soldering.

An outline of the structure of the general SMD LED will be described with reference to the drawings.

FIG. 12 shows a conventional general SMD type LED.
It is a perspective view of. In FIG. 12, an insulating substrate 1 is a resin substrate made of a glass epoxy resin or the like and covered with copper foil on both upper and lower surfaces. A copper plating layer is formed on the entire surface of the insulating substrate 1 by electroless plating, and nickel is formed thereon by electrolytic plating. A plating layer is formed, and a gold plating layer is further laminated thereon by electrolytic plating. The thickness of the plating layer is, for example, about 25 μm.

Further, a plating resist is laminated, exposed and developed to form a pattern, and a pair of upper electrodes 2 facing the upper end of the insulating substrate 1, a pair of lower electrodes 3 facing the lower end, and A side electrode 4 is formed so as to be continuous with the upper electrode 2 and the lower electrode 3. An LED element 5 described later is die-bonded to one upper electrode 2a of the pair of upper electrodes 2, and A
They are connected by a bonding wire 6 made of a u wire or the like. Reference numeral 7 denotes a sealing resin that is sealed with a translucent epoxy resin or the like in order to protect the LED element 5 and the connection portion and effectively emit light from the LED element 5. SMD type L
ED8 is completed.

FIG. 14 and FIG. 15 are a perspective view showing the electrode structure of the LED element and a partially enlarged sectional view in which the LED element is mounted on an insulating substrate by a wire bonding method. FIG.
As shown in FIG. 4 and FIG. 15, the LED element 5 includes an N layer 5b and a P layer 5c with a junction 5a interposed therebetween.
One electrode 5d of the ED element 5, that is, the electrode (cathode electrode) on the N layer 5b side is fixed to the one electrode 2a of the insulating substrate 1 by a fixing means such as a conductive adhesive 11. The other electrode 5 e of the LED element 5, that is, the electrode (anode electrode) on the P layer 5 c side is connected to the other electrode 2 b of the insulating substrate 1 by a bonding wire 6.

FIGS. 16 and 17 are a perspective view showing an electrode structure of another LED element and a partially enlarged sectional view in which the LED element is mounted on an insulating substrate by a non-wire bonding method. As shown in FIGS. 16 and 17, one electrode 5 d of the LED element 5, that is, the electrode (cathode electrode) on the N layer 5 b side is connected to one electrode 2 b of the insulating substrate 1.
The other electrode 5e of the D element 5, that is, the electrode (anode electrode) on the P layer 5c side is connected to the other electrode 2a of the insulating substrate 1.
Are fixed by fixing means such as solder 11a.

Although a glass epoxy substrate is used as the insulating substrate 1, it goes without saying that an alumina ceramic substrate, a plastic film substrate of polyester or polyimide or the like may be used.

The SMD type LED 8 is surface-mounted on a wiring pattern on a motherboard such as a printed board (not shown) by a fixing means such as soldering.

FIG. 13 is a graph showing the relationship between current and heat dissipation (heat generation) in a general SMD type LED. When the horizontal axis represents current IF (mA) and the vertical axis represents heat generation T (° C.), the flowing current and heat generation change substantially linearly, indicating a proportional relationship. The slope of the straight line (a) differs individually depending on the thermal resistance coefficient of the members constituting the SMD type LED.

FIG. 3 is a graph showing the relationship between current and luminance in an SMD type LED. The horizontal axis indicates the current IF (m
A) When the ordinate represents luminance Iv (mcd), it is generally known that the luminance of the LED increases in proportion to the amount of current flowing until the magnitude of the flowing current reaches a predetermined point (A). I have.

[0012]

However, the above-mentioned conventional SMD type LED has the following problems.
That is, as shown in the brightness curve (b) of FIG. 3, the LED needs to flow a large current in order to obtain high brightness, but when the current value is about 300 mA or more, the heat generation of the LED increases, The brightness is saturated and cannot be increased.
This is because a decrease in light conversion efficiency due to heat generation affects luminance. There is a fatal problem that a large amount of current causes an increase in heat and a decrease in luminance.

The present invention has been made in view of the above-mentioned conventional problems, and has an object to prevent heat generation of the LED by radiating heat even when a large current is applied to the LED, thereby realizing high brightness light emission. It is intended to provide a high-brightness SMD-type LED at a low cost.

[0014]

In order to achieve the above object, an SMD type LED according to the present invention is provided with a pair of upper electrodes opposed to an upper end of an insulating substrate, and the pair of upper electrodes are respectively provided. A lower surface electrode on the back surface, a side electrode connected to the upper surface electrode and the lower surface electrode on the side surface, and one electrode of the LED element on the one upper surface electrode,
In the SMD type LED in which the other electrode of the LED element is connected to the other upper electrode and the resin is sealed, a radiating plate made of a conductive member is provided on at least one of the upper electrodes among the pair of upper electrodes. It is characterized by being fixed.

Further, a heat sink is fixed on the one upper electrode, and one electrode of the LED element is connected on the heat sink, and the other electrode of the LED element is connected on the other upper electrode. It is assumed that. .

Further, the heat sink is fixed to a region including the periphery of the die bond area on the one upper electrode, the LED element is die-bonded on the heat sink, and a bonding wire is connected to the other upper electrode. It is characterized by the following.

Further, it is preferable that the heat sink is fixed on the one upper electrode, the LED element is die-bonded directly on the upper electrode including the periphery of the die bonding area, and a bonding wire is connected on the other upper electrode. It is a feature.

Further, the radiating plate is fixed on at least one of the upper electrodes of the pair of upper electrodes, and one electrode of the LED element is directly disposed on the one upper electrode, and the LED is disposed on the other upper electrode. The other electrodes of the element are connected to each other.

A heat sink is fixed on the pair of upper electrodes, and one electrode of the LED element is connected to the one heat sink, and the other electrode of the LED element is connected to the other heat sink. It is characterized by the following.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an SMD type LED according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an SMD type LED according to a first embodiment of the present invention, and FIG.
FIG. 3 is a sectional view taken along the line AA of FIG. 1, and FIG.
It is a graph which shows the relationship between the current of D-type LED, and brightness | luminance.
In the drawings, the same members as those of the prior art are denoted by the same reference numerals.

1 and 2, reference numeral 1 denotes an insulating substrate having a substantially parallelepiped shape, a pair of upper electrodes 2 facing the upper end of the insulating substrate 1, a lower electrode 3 on the lower surface, and the upper electrode 2 The formation of the side surface electrode 4 so as to be continuous with the lower surface electrode 3 is the same as in the above-described related art. In a region including the periphery of the die bonding area 9 of the one upper surface electrode 2a, a radiating plate 10 made of, for example, stainless steel, copper, aluminum, or the like, having conductivity and solder wettability, is fixed with a conductive adhesive 11 or the like. And the L is placed on the heat sink 10.
The ED element 5 is mounted. The other upper surface electrode 2b has A
Wire bonding is performed by a bonding wire 6 made of a u wire or the like. Reference numeral 7 denotes a sealing resin such as a translucent epoxy resin as in the related art. In order to make the heat radiation of the heat radiation plate 10 effective, L is a state in which a part of the heat radiation plate 10 is exposed.
Resin sealing is performed to protect the ED element 5 and the connection part. Thus, the SMD type LED 12 is completed.

The SMD type LED 12 can be surface-mounted on a wiring pattern on a mother board such as a printed board (not shown) by a fixing means such as soldering.

FIG. 3 is a graph showing the relationship between the current and the luminance described above. Curve (b) shows a conventional SMD type LED, and curve (c) shows an SMD type LED to which a heat sink of the present invention is fixed. In FIG. 3, the magnitude of the flowing current is a predetermined point (A).
Up to this point, the brightness of the LED increases in proportion to the current flow, but as described above, the curve (b) shows that the current value is approximately 3
When the current exceeds 00 mA, the heat generated by the LED increases, and the luminance is saturated and cannot be increased. Curve (c) shows that even if the current value becomes approximately 300 mA or more,
Due to the heat radiation effect of the heat radiation plate 10, the brightness of the LED increases.
As shown in FIG. 3, δIv is a luminance increase due to a heat radiation effect when the current value is 300 mA. Since heat is dissipated even when a large current flows, the luminance does not decrease extremely but continues to increase.

FIG. 4 is a sectional view of an SMD type LED according to a second embodiment of the present invention. Without mounting the LED element 5 on the heat sink 10, the heat sink 10 is fixed on one upper electrode 2 a, and the LED element 5 is die-bonded on the upper electrode 2 a including the periphery of the die bond area 9. A bonding wire 6 may be connected on the upper surface electrode 2b. Thus, the SMD LED 12A is completed.

FIG. 5 is a perspective view of an SMD type LED according to a third embodiment of the present invention, and FIG. 6 is a sectional view taken along line BB of FIG. Forming a pair of upper electrodes 2 facing the upper end of the insulating substrate 1, a lower electrode 3 on the lower surface, and forming the side electrodes 4 so as to be continuous with the upper electrode 2 and the lower electrode 3 are the same as those of the related art described above. The same is true. The heat sink 10 is fixed on one upper electrode 2a of the insulating substrate 1 by a fixing means such as a conductive adhesive 11 and the other upper electrode 2a.
One electrode 5e of the LED element 5, that is, the electrode (anode electrode) on the P layer 5c side is directly placed on the
b, the other electrode 5d of the LED element 5, that is, the N layer 5b
Side electrodes (cathode electrodes) are connected to each other, and sealed with a sealing resin 7. As described above, it is needless to say that the spread and heat dissipation of the heat by the radiator plate are made advantageous by securing the surface of the radiator plate 10 exposed from the resin sealing portion as large as possible. Thus, the SMD LED 12B is completed.

FIG. 7 is a sectional view of an SMD type LED according to a fourth embodiment of the present invention. In FIG. 5, the radiator plate 10 is fixed only on one of the upper electrodes 2a, but in FIG. 7, the radiator plate 1 is provided on the pair of upper electrodes 2a, 2b.
0 is fixed, and one electrode 5e of the LED element 5 is directly disposed on the one upper electrode 2a, and the LED 5 is disposed on the other upper electrode 2b.
The other electrode 5d of the element 5 may be connected. Thus, the SMD LED 12C is completed.

FIG. 8 is a sectional view of an SMD type LED according to a fifth embodiment of the present invention. A pair of upper electrodes 2a,
2b, a heat sink 10 is fixed to each of the two heat sinks, one electrode 5d of the LED element 5 is placed on one end of the heat sink 10, and the other electrode 5e of the LED element 5 is placed on the other end of the heat sink 10.
May be connected respectively. By the above, SMD type LED
12D is completed.

FIGS. 9 and 10 show the sixth and seventh embodiments of the present invention.
It is sectional drawing of the SMD type LED which is embodiment of 1st. A heat sink 10 is fixed on the one upper electrode 2a, and one electrode 5e of the LED element 5 is connected to the heat sink 10 and the other electrode 5d of the LED element 5 is connected to the other upper electrode 2b. Thus, the SMD LEDs 12E and 12F are completed.

FIGS. 11 (a), (b), (c) and (d)
FIG. 3 is a plan view of the shape of the heat sink 10 and a state in which the heat sink 10 is arranged on the upper electrode 2. The shape of the heat radiating plate 10 fixed on the upper surface electrode 2 is dispersed and arranged at both ends of only one electrode 2a of the upper surface electrode 2 as shown in FIG. As shown in FIG. 11B, the electrodes 2a and 2b are dispersedly arranged at four corners. As shown in FIG. 11C, the electrodes 2a and 2b are dispersedly arranged at diagonal positions on both ends. As shown in FIG. 11D, the electrodes 2a and 2b are arranged with different sizes. FIG. 11 is an example, and various forms may be adopted for convenience of design.

[0030]

As described above, according to the present invention,
In the SMD type LED, a pair of upper electrodes is provided opposite to the upper end of the insulating substrate, and the pair of upper electrodes are respectively provided on the back surface with a lower electrode, and on the side surface thereof are connected to the upper electrode and the lower electrode. An electrode is formed, and a heat sink made of a conductive member is fixed on at least one of the upper electrodes of the pair of upper electrodes, and an LED element is mounted on the upper electrode or the heat sink, and resin sealing is performed. I do. SMD type L
Even when a large current of about 300 mA or more flows through the ED, heat generated by the LED is diffused and radiated by the heat radiating plate, so that high-luminance light emission can be realized. As a result, the high-brightness LED becomes inexpensive and can be mounted on a high-brightness target product that has not been used conventionally.

[Brief description of the drawings]

FIG. 1 is an SMD type L according to a first embodiment of the present invention.
It is a perspective view of ED.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a graph showing the relationship between current and luminance of conventional and inventive LEDs.

FIG. 4 is an SMD type L according to a second embodiment of the present invention.
It is sectional drawing of ED.

FIG. 5 is an SMD type L according to a third embodiment of the present invention.
It is a perspective view of ED.

FIG. 6 is a sectional view taken along line BB of FIG. 5;

FIG. 7 shows an SMD type L according to a fourth embodiment of the present invention.
It is sectional drawing of ED.

FIG. 8 shows an SMD type L according to a fifth embodiment of the present invention.
It is sectional drawing of ED.

FIG. 9 shows an SMD type L according to a sixth embodiment of the present invention.
It is sectional drawing of ED.

FIG. 10 is a cross-sectional view of an SMD LED according to a seventh embodiment of the present invention.

FIG. 11 is a plan view showing an arrangement of a heat sink according to the present invention.

FIG. 12 is a perspective view of a conventional SMD type LED.

FIG. 13 is a graph showing a relationship between current and heat generation of a general LED.

FIG. 14 is a perspective view showing an electrode structure of the LED element.

FIG. 15 is a partially enlarged cross-sectional view showing a state where the LED element of FIG. 14 is mounted on an insulating substrate by a wire bonding method.

FIG. 16 is a perspective view showing an electrode structure of another LED element.

17 is a partially enlarged cross-sectional view showing a state where the LED element of FIG. 16 is mounted on an insulating substrate by a non-wire bonding method.

[Description of Signs] 1 Insulating substrate 2 Upper electrode 2a One upper electrode 2b The other upper electrode 3 Lower electrode 4 Side electrode 5 LED element 5d One electrode of LED element 5e The other electrode of LED element 6 Bonding wire 7 Sealing Resin 9 Die bond area 10 Heat sink 11 Conductive adhesive 11a Solder 12, 12A, 12B, 12C, 12D, 12E, 12
F SMD LED (b) Luminance curve of conventional SMD LED (c) Luminance curve of SMD LED of the present invention δIv Increase in luminance due to heat dissipation effect

Claims (6)

[Claims] 1. A pair of upper surface electrodes facing an upper surface end of an insulating substrate, wherein each of the pair of upper surface electrodes has a lower surface electrode on a back surface thereof and a side surface connected to the upper surface electrode and the lower surface electrode on a side surface thereof. An electrode is formed, one electrode of the LED element is provided on the one upper electrode, and the LED is provided on the other upper electrode.
In the SMD type LED in which the other electrodes of the element are connected to each other and sealed with a resin, a radiator plate made of a conductive member is fixed on at least one of the upper electrodes among the pair of upper electrodes. SMD LED. 2. A radiator plate is fixed on the one upper surface electrode, and one electrode of the LED element is connected on the radiator plate, and the other electrode of the LED element is connected on the other upper surface electrode. The SMD type LED according to claim 1, wherein 3. The heat sink is fixed to a region including the periphery of a die bond area on the one upper electrode, an LED element is die-bonded on the heat sink, and a bonding wire is connected on the other upper electrode. Claim 1 characterized by the following:
The described SMD type LED. 4. The heat sink is fixed on the one upper electrode, an LED element is die-bonded on the upper electrode including the periphery of the die bonding area, and a bonding wire is connected on the other upper electrode. The SMD type LED according to claim 1, wherein 5. The heat sink is fixed on at least one of the upper electrodes of the pair of upper electrodes, one electrode of the LED element is directly disposed on the one upper electrode, and the LED is disposed on the other upper electrode. The SMD type LED according to claim 1, wherein the other electrodes of the element are connected to each other. 6. The heat sink is fixed to each of the pair of upper electrodes, and one electrode of the LED element is connected to the one heat sink, and the other electrode of the LED element is connected to the other heat sink. The LED according to claim 1, wherein
element.