JP2002208737A - Surface mount semiconductor light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat radiation of a semiconductor light emitting device and attain miniaturization. SOLUTION: The device comprises a support (1), a semiconductor light emitting element (2) fixed to the support (1), a first outer lead (3) disposed with a fixed distance from the support (1) and electrically connected to an electrode of the light emitting element (2), and a resin seal (4) covering the light emitting element (2) and the first lead (3). The support (1) is made of a metal and has an adhesive part 1a projecting from the resin seal (4), the adhesive part 1a of the support (1) is fixed to a wiring board (5) to form a gap (6) between the resin seal (4) and the wiring board (5), and the heat generated from the light emitting element (2) during operating is discharged from the adhesive part (1a) through the gap (6) into the ambient air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor light emitting device,
More particularly, the present invention relates to a surface-mount type semiconductor light emitting device having high heat dissipation.

[0002]

2. Description of the Related Art In a GaN-based semiconductor light emitting device using a sapphire substrate, it is not necessary to use an insulating substrate, but a conventional surface mount type light emitting device using a general semiconductor light emitting device having an N electrode or a P electrode on the back surface. In the structure of the semiconductor light emitting device,
It is necessary to prevent a short circuit between a P electrode and an N electrode by forming a plurality of separated conductor patterns on an insulating substrate and fixing a semiconductor light emitting element on some of the conductor patterns.

[0003] For example, an insulating substrate made of light-reflective epoxy resin or ceramic is prepared, and wiring, element mounting surfaces, and external extraction are made using a metal conductor such as silver (Ag) or copper (Cu). Terminals are patterned on the surface of the insulating substrate. At this time, a plurality of metal external leads are formed so as to surround the insulating substrate. After mounting an electronic component including a semiconductor light emitting element at a predetermined position on the wiring conductor, the surface of the insulating substrate and the electronic component are sealed with a light transmitting resin such as an epoxy resin to form a mold structure.

In operation, when a voltage is applied between a plurality of external leads of the semiconductor light emitting device, a forward current flows from the anode electrode to the cathode electrode of the semiconductor light emitting device, and the semiconductor light emitting device is turned on. At the time of lighting, a part of the power loss generated by the operating current and the voltage drop of the semiconductor light emitting element is dissipated by the heat generated by the semiconductor light emitting element. In particular, a gallium nitride based semiconductor light emitting element used in a blue light emitting semiconductor device has a large voltage drop and large power loss. The amount of heat generated by the semiconductor light emitting device is Q (° C.), the amount of power loss is W (W), the thermal conductivity of the semiconductor light emitting device is λ ₀ , the thermal conductivity of the insulating substrate and the conductor pattern portion is λ ₁ , Assuming that the thermal conductivity is λ ₂ , the calorific value of the semiconductor light emitting device is expressed by the following equation (1). The unit of each thermal conductivity in the denominator of the formula (1) is (W / ° C)
It is. Q = W / (λ ₀ × λ ₁ × λ ₂ ) (1) Normally, assuming that the heat generation amount of the semiconductor light emitting element is Tb and the ambient temperature is Ta, the PN junction temperature Tj of the semiconductor light emitting element which is weak to heat is limited. It is necessary to operate the semiconductor light emitting device within a temperature range that does not exceed the maximum rated value Tjmax and satisfies the expression (2). Tjmax> Ta + Tb (2)

[0005] When the thermal conductivity of the semiconductor light emitting element, the insulating substrate, the conductor pattern and the mounting substrate is low, various problems occur. First, there is a material for a semiconductor light emitting device in which the PN junction temperature Tj increases and the luminous intensity decreases due to a change in temperature characteristics. For example, in an AlGaInP-based semiconductor light emitting device, 2
At 0 mA, the luminous intensity decreases by -0.5 to -1% / ° C. Second, there is a disadvantage that the range of the ambient temperature Ta when the semiconductor light emitting device is operated is limited to the range of the equations (1) and (2). Third, when a semiconductor light emitting device is connected to a constant voltage source via a resistor and driven at a constant voltage, the forward voltage value decreases due to an increase in the PN junction temperature Tj. For this reason, the operating point fluctuates, the current value flowing through the semiconductor light emitting element increases, the calorific value of the semiconductor light emitting element hardly saturates, and the heat generation and the current value increase are repeated, leading to thermal runaway. Fourth, peeling occurs at the interface between the mold resin and the semiconductor light emitting element, and the light emitted from the semiconductor light emitting element is totally reflected at the peeled portion and the luminous intensity is reduced, thereby lowering the reliability of the product. Fifth, PN
As the junction temperature Tj increases, thermal degradation of the semiconductor light emitting element occurs, and reliability decreases.

In order to reduce the above-mentioned inconvenience, it is important how the temperature rise of the semiconductor light emitting device can be suppressed.
In order to reduce the calorific value of the semiconductor light emitting device driven by a constant drive current, the thermal conductivity λ ₀ of the semiconductor light emitting element can be increased or the insulating substrate / conductor pattern can be reduced according to equations (1) and (2). either way increase the thermal conductivity lambda ₂ of or mounting substrate should be reviewed higher or materials used a thermal conductivity lambda ₁ is considered. Instead of increasing the thermal conductivity λ ₀ of the semiconductor light emitting element, a method of increasing the heat capacity by increasing the size of the semiconductor light emitting element can be considered. In this method, an insulating substrate having a large area corresponding to the increased size is considered. Is required, it is difficult to reduce the size of the semiconductor light emitting device, and the luminous efficiency of the semiconductor light emitting element is reduced. Even when increasing the thermal conductivity lambda ₂ of the mounting board, to improve the heat dissipation effect by widening a conductive pattern of the surface to be adhered to the mounting substrate and the semiconductor light emitting device, can be reduced the amount of heat generated by the semiconductor light emitting device, correspondingly mounted Since the area of the substrate increases, the manufacturing cost increases. Thus, possible to review the insulating substrate and the thermal conductivity lambda ₁ enhanced or materials used in the conductive pattern, characteristic surface, it is most effective at the mounting surface and cost.

For example, Japanese Patent Application Laid-Open No. 2000-77686 discloses that a semiconductor device thinned by transmitting an optical signal from a package side wall is mounted with the back surface of the island fixed to a printed wiring to mount the semiconductor device. And a mounting structure of the optical semiconductor device for improving heat dissipation. In this mounting structure, the heat radiation of the semiconductor light emitting element can be improved by thermally coupling the island to the printed wiring without using the insulating substrate. This structure has excellent heat dissipation compared to conventional semiconductor light-emitting devices that use an insulating substrate, but requires the bending of leads and increases the size of the device, making miniaturization difficult and increasing costs. There is a drawback that can be connected.

[0008]

As described above, it has been necessary to use a typical insulating substrate such as a ceramic substrate made of alumina, because of the structural limitation of the semiconductor light emitting device. A typical metal conductor to be patterned on an insulating substrate is silver or copper. The thermal conductivity of alumina is 21 (W / m / K) at room temperature, and silver (Ag) at 100 ° C.
Of 313 (W / m / K) and 395 (W / m / K) of copper (Cu). By the way,
The thermal conductivity of iron at 100 ° C. is 72 (W / m / K).
For this reason, a method of improving heat dissipation through a conductor pattern is conceivable. However, in general, a conductor pattern formed to a thickness of about 50 μm cannot be expected to have a heat dissipation effect, and a manufacturing process in which an insulating substrate is sandwiched between metal leads is required. To increase. Thermal conductivity can be improved by reducing the thickness of the insulating substrate, but if the thickness is reduced to some extent, the mechanical strength of the insulating substrate is reduced, and problems such as warpage and chipping of the insulating substrate occur. It becomes easy to handle. Heat is radiated from the insulating substrate only to the external electrode terminals bonded to the mounting substrate.
If the bonding area with the mounting substrate is small, the heat dissipation is reduced, but if the contact area is increased, the area of the semiconductor light emitting device is correspondingly increased. An object of the present invention is to provide a small semiconductor light emitting device having excellent heat dissipation.

[0009]

A surface-mounted semiconductor light emitting device according to the present invention comprises a support (1), a semiconductor light emitting element (2) fixed to the support (1), and a support (1). A first external lead (3) disposed at a fixed distance and electrically connected to an electrode of the semiconductor light emitting device (2); a support (1); a semiconductor light emitting device (2); A resin sealing body (4) for covering the lead (3). The support (1) is formed of metal and has an adhesive portion (1a) protruding from the resin sealing body (4), and the adhesive portion (1a) of the support (1) is fixed to the wiring board (5). When the gap (6) is formed between the resin sealing body (4) and the wiring board (5), the heat generated from the semiconductor light emitting element (2) during operation is Released from (1a) into the surrounding air.

In the embodiment of the present invention, since the bottom surface (1b) of the support body (1) and the bottom surface (3a) of the first external lead (3) are arranged on the same plane, a planar wiring board is provided. (5) Support on top
The bottom surface (1b) of (1) and the bottom surface (3a) of the first external lead (3) can be fixed with a conductive adhesive. The support (1) and the first external lead (3) are arranged at the same height. The support (1) has a single or a plurality of element mounting portions (7). The support (1) may constitute a second external lead that is separated from the first external lead (3). A third external lead (9) electrically connected to the electrode of the semiconductor light emitting element (2) and formed at the same height as the support (1) and the first external lead (3) may be provided. Good. The bottom surface (9a) of the third external lead (9) is arranged on the same plane as the bottom surface (1b) of the support (1) and the bottom surface (3a) of the first external lead (3).

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a surface-mounted semiconductor light emitting device according to the present invention will be described below with reference to FIGS.

In the first embodiment of the present invention shown in FIGS. 1 and 2, a surface mount type semiconductor light emitting device comprises: a support (1) having a single flat element mounting portion (7); A semiconductor light-emitting element (2) fixed to an element mounting portion (7) of a support (1) by an adhesive (13); and a semiconductor light-emitting element (2) disposed at a predetermined distance from the support (1). ) And an anode electrode (2) of the semiconductor light emitting device (2).
a) a first lead wire (8a) for electrically connecting the first external lead (3) to a first external lead (3); and a cathode electrode of the semiconductor light emitting element (2).
A second thin lead wire (8b) for electrically connecting (2b) and a support (1) constituting a second external lead which is separated from the first external lead (3), and a support (1) , A semiconductor light emitting element (2), a first external lead (3), a resin thin body (4) for covering the first fine lead (8a) and the second fine lead (8b). Flat element mounting part (7) for mounting semiconductor light emitting element (2)
Is provided on each bottom surface of one or more concave portions (1c) formed on the support (1) and having a light-condensing action. In order to improve the light reflection efficiency of the concave portion (1c), the inclination of θ = 30 to 60 °
It is desirable to form a metal plating with high light reflectivity such as silver (Ag) or aluminum (Al) on the inside of the concave portion (1c) in addition to being formed on the side wall surface of c). The support (1) is made of copper (C
u) and a resin-encapsulated body made of a metal having high heat conductivity and excellent heat dissipation, such as an alloy using copper (Cu)
Has an adhesive portion (1a) projecting downward from The bonding portion (1a) is fixed to a land (10) formed on the wiring board (5) by solder (12), and the bottom (3a) of the first external lead (3) is
Land (11) formed on wiring board (5) apart from (10)
Is fixed by solder (12). As the adhesive (13) for bonding the semiconductor light emitting element (2) to the element mounting portion (7), it is desirable to use a highly reflective conductive paste such as silver (Ag). Further, since the back surface of the semiconductor light emitting element (2) having high light transmittance is an insulator, a non-conductive transparent adhesive may be used as the adhesive (13). The first and second lead wires (8a, 8b) are made of gold (A
u) or a metal such as aluminum (Al). The bonding portion (1a) serving as a heat radiating portion is exposed from the resin sealing body (4) having a high light transmission property such as an epoxy type, and the bonding portion (1
When a) is fixed to the wiring board (5), a gap (6) is formed between the resin sealing body (4) and the wiring board (5). The height of the gap (6) can be freely set within a range of 0.1 to 2.0 mm. Therefore, the size in the horizontal direction can be reduced as compared with the conventional structure in which the external leads protrude from the side surface of the resin sealing body. The support (1) and the first external lead (3) are arranged at the same height and in parallel. Since the bonding portion (1a) of the support (1) and the bottom surface (3a) of the first external lead (3) are arranged on the same plane, the bonding portion (1a) of the support (1) and the first The bottom surface (3a) of the external lead (3) can be fixed on the planar wiring board (5) by the solder (12) serving as a conductive adhesive.

In the second embodiment of the present invention shown in FIGS. 3 and 4, the semiconductor device is electrically connected to the cathode electrode (2b) of the semiconductor light emitting device (2) through the second lead wire (8b). A third external lead (9), which is spaced apart from the support (1), is the same as the support (1) and the first external lead (3). The bottom surface (9a) of the third external lead (9) is formed with the bottom surface (1b) of the support (1) and the first external lead.
It is arranged on the same plane as the bottom surface (3a) of (3) and in parallel.
The semiconductor light emitting device (2) shown in FIGS. 3 and 4 has a sapphire substrate which is an insulator, and a P formed on the sapphire substrate.
An anode electrode (2a) and a cathode electrode (2b) are formed on the element surface.

When the semiconductor light emitting device is operated, heat generated from the semiconductor light emitting element (2) is transferred from the resin sealing body (4) to the gap.
(6) is transmitted to the land (10) from the bonding part (1a) exposed in the gap (6) and directly from the bonding part (1a) or the land (10).
It is released into the air inside, and the heat radiation effect can be improved. In this case, by shortening the distance between the element mounting portion (7) and the bottom surface of the support (1) and enlarging the area of the support (1) or the land (10), it is possible to further enhance heat radiation. It is possible.
Usually, the wiring forming the common circuit line including the power supply line and the ground line on the wiring board (5) is made of a relatively thick copper to reduce the impedance component and prevent the oscillation of the voltage applied to the common line. It is formed by a foil pattern. For this reason, it is desirable that the land (10) to which the support (1) is adhered be a common line. In the present embodiment, it also plays the role of a jumper wire straddling the land (10). For this reason, by removing the patterned copper foil pattern, it is possible to reduce the number of jumper wires and reduce the temperature rise of the semiconductor light emitting device, to reduce the size of the wiring board (5), and to reduce the mounting cost. it can. When the support (1) and the semiconductor light emitting element (2) are kept in an electrically insulated state, the wiring board
The light emitting element (2) can operate stably regardless of the voltage or current conditions applied to the land (10) of (5).

FIG. 5 shows a support (1) and a first external lead (3).
A third embodiment in which side emission can be performed by fixing a third external lead (9) vertically on a wiring board (5) is shown.
FIG. 6 shows a fourth embodiment in which two element mounting portions (7) are vertically arranged side by side on a support (1) fixed vertically to a wiring board (5) to enable side emission. The semiconductor light emitting device (2) arranged on the upper side of FIG. 6 has the same structure as the semiconductor light emitting device (2) shown in FIG. 2, and the semiconductor light emitting device (2) arranged on the lower side of FIG.
In (2), a thin lead (8) is placed on the surface from the third external lead (9).
An anode electrode (2a) to which power is supplied from a) is formed,
On the back surface, a cathode electrode electrically connected to the support (1) is formed. FIG. 6 shows an example of development to a two-color light emitting device in which a pair of semiconductor light emitting elements (2) share a common cathode electrode. Since the first external lead (3) and the third external lead (9) to be connected to the anode electrode (2a) of each semiconductor light emitting element (2) are different in length, it is easy to identify the external lead. Become.

FIG. 7 shows a fifth embodiment in which two semiconductor light emitting elements (2) are arranged on a single element mounting portion (7).
The upper semiconductor light emitting element (2) shown in FIG.
6 has the same structure as the semiconductor light emitting element (2) shown in the upper part of FIG. 6, and has an anode electrode (2a) electrically connected to the first external lead (3c) separated through the same. The semiconductor light emitting device (2) includes an anode electrode (2a) electrically connected to a first external lead (3d) separated via a thin lead wire (8a), and the semiconductor light emitting device shown in the lower part of FIG. Shows the same structure as (2). In the embodiment shown in FIG. 7, the same element mounting portion
A two-color semiconductor light emitting device using each of the first semiconductor light emitting element (2) and the second semiconductor light emitting element (2) mounted on (7) is shown.

FIG. 8 shows a semiconductor light emitting element (2) fixed to the upper side of the support (1), a constant voltage diode (14) fixed to the lower side, and the semiconductor light emitting element (2) and the constant voltage diode (14). ) Shows a sixth embodiment connected to a single first external lead (3) and constituting the circuit shown in FIG. The constant voltage diode (14) turns on when a reverse voltage is applied to the semiconductor light emitting device (2), and protects the semiconductor light emitting device (2) against the reverse voltage. Further, when a surge voltage is applied, the semiconductor light emitting device (2) has a function of protecting the semiconductor light emitting element (2) from the surge voltage.
In the constant voltage diode (14), an anode electrode (14a) connected to the first external lead (3) via a thin lead wire (8a) is formed on the surface, and is electrically connected to the support (1). The formed cathode electrode is formed on the back surface. FIG. 10 shows a seventh embodiment in which first external leads (3c, 3d) provided separately are connected via thin lead wires (8a).

The embodiment shown in FIG. 10 shows a first semiconductor light emitting device (2) and a second semiconductor light emitting device which are mounted on independent device mounting portions (7) and have independent cathode electrodes.
2 shows a two-color semiconductor light emitting device provided with (2). FIG. 11 shows that each anode electrode of the semiconductor light emitting element (2) and the constant voltage diode (14) is connected to a first external lead (3c, 3c) provided separately.
Semiconductor light-emitting device connected to d) via fine lead wire (8a)
An eighth embodiment including (2) and an integrated circuit (15) for controlling or protecting the semiconductor light emitting device (2) is shown. When a white semiconductor light emitting device is configured, the temperature rise can be suppressed, and the deterioration of the semiconductor light emitting element and the phosphor can be suppressed. Discoloration due to a decrease in the light emitting effect can be suppressed, and a stable color tone can be displayed.

In the embodiment of the present invention, good heat radiation can be obtained, and the following effects can be obtained. [1] Improvement of heat dissipation Support having an adhesive part (1a) that becomes a fin exposed to the outside
Since the semiconductor light emitting element (2) is directly bonded to (1), good heat dissipation can be obtained. If the area of the copper foil portion such as the land (10) is expanded as necessary, the heat dissipation can be further improved, and the effect of improving the thermal derating characteristics can be expected. [2] Improvement in productivity If the semiconductor light emitting device (2) is bonded to the support (1), for example,
A special process including a process of sandwiching the lead between the insulating substrates and an additional component are not required, and the manufacturing can be performed using the existing production equipment. Since existing equipment can be used without the need for new equipment, there are also advantages in terms of productivity and cost. [3] Miniaturization Using a material having good heat conductivity, the area of the support body (1) is reduced, the semiconductor light emitting device is downsized, and the semiconductor light emitting device is driven at a high current while ensuring heat dissipation. it can. Further, the effect of reducing the area of the wiring board (5) and the number of components can be expected. [4] Reliability Since the number of parts is smaller than that of the conventional product, the reliability is improved.

[0020]

As described above, according to the present invention, it is possible to realize a small semiconductor light emitting device having excellent heat dissipation.

[Brief description of the drawings]

FIG. 1 is a side view showing a first embodiment of a surface mounted semiconductor light emitting device according to the present invention.

FIG. 2 is a plan view of FIG. 1;

FIG. 3 is a side view showing a second embodiment of the surface mounted semiconductor light emitting device of the present invention.

FIG. 4 is a plan view of FIG. 3;

FIG. 5 is a side view showing a third embodiment of the surface mounted semiconductor light emitting device of the present invention.

FIG. 6 is a side view showing a fourth embodiment of the surface mounted semiconductor light emitting device of the present invention.

FIG. 7 is a plan view showing a fifth embodiment of the surface-mounted semiconductor light emitting device according to the present invention.

FIG. 8 is a plan view showing a sixth embodiment of the surface-mounted semiconductor light emitting device according to the present invention.

9 is an electric circuit diagram showing a circuit configuration of the surface-mounted semiconductor light emitting device shown in FIG.

FIG. 10 is a plan view showing a seventh embodiment of the surface-mounted semiconductor light-emitting device according to the present invention.

FIG. 11 is a cross-sectional view illustrating an eighth embodiment of the surface-mounted semiconductor light emitting device according to the present invention.

[Explanation of symbols]

(1) ··· Support (second external lead), (1a) ··· adhesive part, (1b) ··· bottom, (2) ·· semiconductor light emitting element, (3) ·
・ First external lead, (3a) ・ ・ Bottom surface, (4) ・ ・ Resin sealing body, (5) ・ ・ Wiring board, (6) ・ ・ Gap, (7) ・
・ Element mounting part, (8a) ・ ・ First lead wire, (8b) ・ ・
Second fine lead, (9) .. 3rd external lead, (9
a)

Claims (6)

[Claims] 1. A support, a semiconductor light-emitting device fixed to the support, and a first external device arranged at a predetermined distance from the support and electrically connected to an electrode of the semiconductor light-emitting device. In a surface-mounted semiconductor light emitting device including a lead and a resin sealing body that covers the support, the semiconductor light emitting element, and the first external lead, the support is formed of metal and is formed of a metal. A surface mounting type semiconductor light emitting device having a projecting adhesive portion, wherein a gap is formed between the resin sealing body and the wiring substrate when the adhesive portion of the support is fixed to the wiring substrate. . 2. The surface-mounted semiconductor light emitting device according to claim 1, wherein a bottom surface of the support and a bottom surface of the first external lead are arranged on the same plane. 3. The surface-mounted semiconductor light emitting device according to claim 1, wherein the support and the first external lead are arranged at the same height. 4. The surface-mounted semiconductor light emitting device according to claim 1, wherein the support has a single or a plurality of element mounting portions. 5. The surface-mounted semiconductor light-emitting device according to claim 1, wherein the support forms a second external lead separated from the first external lead. 6. A third external lead electrically connected to an electrode of the semiconductor light emitting element, the third external lead being formed at the same height as the support and the first external lead. The surface-mounted semiconductor light emitting device according to claim 1, wherein a bottom surface of the third external lead is disposed on the same plane as a bottom surface of the support and a bottom surface of the first external lead. apparatus.