JP2003008078A - Surface mounting semiconductor light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a surface mounting semiconductor light emitting device in which heat dissipation properties are improved while reducing the size. SOLUTION: The other flat major surface (1b) of the supporting plate (1) for a surface mounting semiconductor light emitting device projects from the bottom face (4a) of a resin sealing body (4) and a first external lead (3) extending along the edge part (1e) of the supporting plate (1) has a flat bottom face (3a) projecting from the bottom face (4a) of the resin sealing body (4) in the same direction as the other major surface (1b) of the supporting plate (1). When the other major surface (1b) of the supporting plate (1) is bonded to a wiring board (5), a gap (6) is formed between the resin sealing body (4) and the wiring board (5) and the lower parts of the supporting plate (1) and the first external lead (3) are exposed to the outer air in the gap (6) formed between the bottom face (4a) of the resin sealing body (4) and the wiring board (5).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a semiconductor light emitting device,
In particular, the present invention relates to a surface mount semiconductor light emitting device having high heat dissipation.

[0002]

2. Description of the Related Art As shown in FIGS. 12 and 13, metal leads (51, 52) electrically separated from each other are formed on one main surface of an insulating substrate (1). The semiconductor light emitting device (2) is fixed to 51), the electrode of the semiconductor light emitting device (2) is electrically connected to the other lead (52) through the thin lead wire (53), and the semiconductor light emitting device (2) is also connected. A surface mount type semiconductor device in which a resin sealing body (4) is formed on one main surface of an insulating substrate (1) so as to cover the lead thin wire (53) is known.
Each lead (51, 52) extends from one main surface of the insulating substrate (1) to the bottom surface along the side surface of the insulating substrate (1), and each lead (51, 52) is a wiring board at the bottom surface. Soldered to the corresponding land (10) of (5).

In operation, when a voltage is applied between the leads (51, 52) of the surface-mounted semiconductor light emitting device, the semiconductor light emitting element
A forward current flows from the anode electrode to the cathode electrode of (2), 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 (2) is dissipated by the heat generation of the semiconductor light emitting element (2). In particular, the gallium nitride-based semiconductor light emitting element used for the blue light emitting semiconductor device has a large voltage drop and loss power. The heat generation amount of the semiconductor light emitting element is Q (° C.), the amount of power loss is W (W), the thermal conductivity of the semiconductor light emitting element (2) is λ ₀ , the insulating substrate (1) and the land (conductor pattern portion) (10 the thermal conductivity lambda ₁ of) the wiring thermal conductivity of the substrate (5) and lambda _2, the amount of heat generated in the semiconductor light-emitting device is expressed by equation (1). The unit of each thermal conductivity in the denominator shown in the formula (1) is (W / ° C). Q = W / (λ ₀ × λ ₁ × λ ₂ ) (1) Usually, the heat generation amount of the semiconductor light emitting device (2) is Tb, and the ambient temperature is Ta.
Then, it is necessary to operate the semiconductor light emitting device within a temperature range that satisfies the formula (2) without exceeding the maximum rated value Tjmax that limits the PN junction temperature Tj of the semiconductor light emitting element (2) which is weak against heat. Tjmax> Ta + Tb (2)

When the semiconductor light emitting device (2), the insulating substrate (1), the land (10) and the wiring substrate (5) have low thermal conductivity, various problems occur. Firstly, there is also a material for a semiconductor light emitting element in which the PN junction temperature Tj rises and the luminous intensity is lowered due to a change in temperature characteristics. For example, in an AlGaInP-based semiconductor light emitting device, the luminous intensity is reduced by −0.5 to −1% / ° C. at 20 mA. Second
In addition, there is a drawback that the range of the ambient temperature Ta at the time of operating the semiconductor light emitting device is limited to the ranges of the expressions (1) and (2).
Thirdly, when the semiconductor light emitting element is connected to a constant voltage source via a resistor and constant voltage driving is performed, the forward voltage value decreases due to an increase in the PN junction temperature Tj. For this reason, the operating point fluctuates, the value of the current flowing through the semiconductor light emitting element increases, the amount of heat generated by the semiconductor light emitting element becomes difficult to saturate, and heat generation and current value increase are repeated, leading to thermal runaway. Fourthly, 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 to reduce the luminous intensity, resulting in a decrease in product reliability. Fifth, PN
As the junction temperature Tj rises, thermal degradation of the semiconductor light emitting element occurs and reliability decreases.

In order to reduce the above problems, the point is how to suppress the temperature rise of the semiconductor light emitting device.
In order to reduce the heat generation amount of the semiconductor light emitting device driven by a constant drive current, the thermal conductivity λ ₀ of the semiconductor light emitting element should be increased or the insulating substrate / conductor pattern should be formed according to the equations (1) and (2). Either increasing the thermal conductivity λ ₁ or reviewing the material used, or increasing the thermal conductivity λ ₂ of the mounting board can be considered. Instead of increasing the thermal conductivity λ ₀ of the semiconductor light emitting element, a method of increasing the size of the semiconductor light emitting element to increase the heat capacity can be considered. In this method, an insulating substrate having a large area corresponding to the increasing size is used. Therefore, 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 the thermal conductivity λ ₂ of the mounting board is increased, the conductor pattern on the bonding surface between the mounting board and the semiconductor light emitting device can be widened to improve the heat dissipation effect and reduce the heat generation amount of the semiconductor light emitting device. Since the board area is expanded, the manufacturing cost is increased. Therefore, increasing the thermal conductivity λ ₁ of the insulating substrate and the conductor pattern or reviewing the materials used is most effective in terms of characteristics, mounting and cost.

For example, Japanese Patent Laid-Open No. 2000-77686 discloses that a semiconductor device thinned by transmitting an optical signal from a package side wall is mounted by fixing the back surface of an island to a printed wiring to cause optical signal blurring. And a mounting structure of an optical semiconductor device for improving heat dissipation. In this mounting structure, the heat dissipation of the semiconductor light emitting element can be improved by thermally coupling the island to the printed wiring without using an insulating substrate. With this structure, the heat dissipation is much better than that of the conventional semiconductor light emitting device that uses an insulating substrate, but on the other hand, the leads must be bent and the device becomes large, making it difficult to miniaturize and increasing the cost. There are difficulties connected.

[0007]

As described above, due to the structural restrictions of the semiconductor light emitting device, it has been necessary to use an insulating substrate such as a typical alumina ceramic substrate in the past. A typical metal conductor patterned on an insulating substrate is silver or copper, but the thermal conductivity of alumina is 21 (W / m / K) at room temperature, and silver (Ag) at 100 ° C.
The thermal conductivity is 313 (W / m / K) and that of copper (Cu) is 395 (W / m / K). By the way,
The thermal conductivity of iron at 100 ° C. is 72 (W / m / K).
Therefore, a method of improving heat dissipation through a conductor pattern is conceivable, but a heat dissipation effect cannot be expected for a conductor pattern generally formed with a thickness of about 50 μm, and a manufacturing process in which an insulating substrate is sandwiched by metal leads is required. To increase. The thermal conductivity can be improved by making the insulating substrate thinner, but if it is made thinner to some extent, the mechanical strength of the insulating substrate will decrease, causing problems such as warping or chipping of the insulating substrate. It becomes easy and difficult to handle. Heat is radiated from the insulating substrate only through the external electrode terminals that are attached to the mounting substrate.
When the adhesion area with the mounting substrate is narrow, the heat dissipation performance is reduced, while conversely, when the contact area is increased, the area of the semiconductor light emitting device is correspondingly widened. An object of the present invention is to provide a small semiconductor light emitting device having excellent heat dissipation.

[0008]

A surface mount type semiconductor light emitting device according to the present invention comprises a support plate (1) and a single or a plurality of elements provided on one main surface (1a) of the support plate (1). A semiconductor light emitting element (2) fixed to the mounting portion (7) and a first light emitting element (2) arranged at a constant distance from the support plate (1) and electrically connected to an electrode of the semiconductor light emitting element (2). It comprises an external lead (3), a support plate (1), a semiconductor light emitting element (2) and a resin encapsulant (4) covering the first external lead (3). The other flat main surface (1b) of the support plate (1) projects from the bottom surface (4a) of the resin encapsulant (4) and extends along the edge (1e) of the support plate (1). External lead
(3) has a flat bottom surface (3a) protruding from the bottom surface (4a) of the resin sealing body (4) in the same direction as the other main surface (1b) of the support plate (1). When the other main surface (1b) of the support plate (1) is fixed to the wiring board (5), a gap (6) is formed between the resin sealing body (4) and the wiring board (5).
And the lower portion of the support plate (1) and the first portion within the gap (6) formed between the bottom surface (4a) of the resin encapsulant (4) and the wiring board (5). Since the lower part of the external lead (3) is exposed to the external air, the heat generated from the semiconductor light emitting element (2) during operation is released into the ambient air from the adhesive part (1d) within the gap (6). .

In the embodiment of the present invention, the other main surface (1b) of the support plate (1) and the bottom surface (3a) of the first external lead (3) are
Since they are arranged on the same plane, the other main surface (1
b) and the bottom surface (3a) of the first external lead (3) can be simultaneously fixed to the land (10) of the planar wiring board (5) with a conductive adhesive. Support plate (1) and first external lead
(3) are arranged at the same height, and the support plate (1) constitutes a second external lead which is separated from the first external lead (3), and is electrically connected to the electrode of the semiconductor light emitting device (2). Connected to and support plate (1)
And the third external lead (9) is formed at the same height as the first external lead (3), and the other main surface (1b) of the support plate (1) and the first external lead (3) are formed.
The bottom surface (9a) of the third external lead (9) may be arranged on the same plane as the bottom surface (3a) of the external lead (3).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a surface mount 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 semiconductor light emitting device is a support plate (1) having a single flat element mounting portion (7), The semiconductor light emitting element (2) fixed to the element mounting portion (7) of the support plate (1) by an adhesive material (13), and the semiconductor light emitting element (2) arranged at a constant distance from the support plate (1). ) And the first external lead (3) electrically connected to the electrode of the semiconductor light emitting device (2).
a thin lead wire (8a) for electrically connecting (a) and the first external lead (3), and a cathode electrode of the semiconductor light emitting device (2)
A second lead thin wire (8b) electrically connecting the support plate (1) constituting the second outer lead separated from the first outer lead (3) with the support plate (1). A semiconductor light emitting element (2), a first external lead (3), a first lead thin wire (8a) and a second lead thin wire (8b), and a resin sealing body (4). Flat element mounting part (7) for mounting semiconductor light emitting element (2)
Are provided on the bottom surface of each of the single or plural recesses (1c) having a light-collecting function formed on the support plate (1). In order to improve the light reflection efficiency of the concave portion (1c), an inclination of θ = 30 to 60 ° is used.
It is desirable to form a metal plate having a high light reflectance such as silver (Ag) or aluminum (Al) on the inner side of the concave portion (1c) while being formed on the side wall surface of c). The support plate (1) is made of copper (C
u) and a resin sealing body (4) made of a metal having a high heat conductivity and an excellent heat dissipation property such as an alloy using copper (Cu)
It has an adhesive portion (1d) protruding downward from. The adhesive portion (1d) of the support plate (1) is fixed to the land (10) formed on the wiring board (5) by solder (adhesive material) (12), and the first external lead
(3) extends along the edge (1e) of the support plate (1). The first external lead (3) is a flat bottom surface protruding from the bottom surface (4a) of the resin encapsulant (4) in the same direction as the other main surface (1b) of the support plate (1).
It has (3a). The bottom surface (3a) of the first external lead (3) is separated from the land (10) and is formed on the wiring board (5).
It is fixed to (11) with solder (12).

As the adhesive material (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 device (2) having high light transmittance is an insulator, the adhesive material (13)
Alternatively, a non-conductive transparent adhesive material may be used. The first and second thin lead wires (8a, 8b) are made of metal such as gold (Au) or aluminum (Al). The other main surface (1b) of the support plate (1) and the adhesive portion (1d) that becomes the heat dissipation portion are exposed from the bottom surface (4a) of the resin encapsulant (4) having high light transmittance such as epoxy and are supported. When the adhesive portion (1d) of the plate (1) 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 the range of 0.1 to 2.0 mm. Therefore, the projecting height of the semiconductor light emitting element (2) from the wiring board (5) and the lateral size can be reduced as compared with the conventional structure in which the external leads project from the side surface of the resin sealing body. The support plate (1) and the first outer leads (3) are arranged at the same height and in parallel. Support plate
Since the adhesive portion (1d) of (1) and the bottom surface (3a) of the first external lead (3) are arranged on the same plane, the adhesive portion (1d) of the support plate (1)
Also, the bottom surface (3a) of the first external lead (3) can be fixed on the planar wiring board (5) by the solder (12) which is a conductive adhesive material.

In the second embodiment of the present invention shown in FIGS. 3 and 4, it is electrically connected to the cathode electrode (2b) of the semiconductor light emitting device (2) through the second lead thin wire (8b). The third external lead (9), which has a third external lead (9) and is spaced apart from the support plate (1), is the same as the support plate (1) and the first external lead (3). The bottom surface (9a) of the third external lead (9) is the same as the other main surface (1b) of the support plate (1) and the bottom surface (3a) of the first external lead (3). They are arranged on a plane and in parallel. The semiconductor light emitting device (2) shown in FIGS. 3 and 4 includes a sapphire substrate that is an insulator and a PN junction formed on the sapphire substrate, and the anode electrode (2a) is formed on the device surface.
And a cathode electrode (2b) is formed.

When operating the semiconductor light emitting device, the heat generated from the semiconductor light emitting element (2) is separated from the resin sealing body (4) by a gap.
It is transmitted from the adhesive part (1d) exposed in (6) to the land (10), and the gap (6) is directly transmitted from the adhesive part (1d) or the land (10).
It is released into the air inside and the heat dissipation effect can be improved. In this case, by shortening the distance between the element mounting portion (7) and the bottom surface of the support plate (1) and enlarging the area of the support plate (1) or the land (10), heat dissipation can be further improved. 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) lowers the impedance component and prevents the voltage applied to the common line from oscillating. It is formed by a foil pattern. For this reason, it is desirable that the land (10) for adhering the support plate (1) to be on a common line. In the present embodiment, it also plays the role of a jumper wire straddling the land (10). Therefore, by removing the patterned copper foil pattern, it is possible to reduce the number of jumper wires and the temperature rise of the semiconductor light emitting device, and it is possible to reduce the size of the wiring board (5) and reduce the mounting cost. it can. When the support plate (1) and the semiconductor light emitting device (2) are held 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). In the second embodiment of the present invention shown in FIGS. 3 and 4, the side surface of the support plate (1), the side surface of the first external lead (2) and the side surface of the third external lead (9) are resin-sealed. It projects from the side surface of the stopper (4). Therefore, as shown in FIG. 3, the other main surface (1b) of the support plate (1) can be fixed to the wiring board (5) by facing it, and as shown in FIG. It is also possible to fix the side surface of the support plate (1) so as to face it with respect to 5).

FIG. 5 shows a third embodiment in which the semiconductor light emitting device shown in FIGS. 3 and 4 is vertically fixed on a wiring board (5) and side light emission is possible. Also in the third embodiment, since the other main surface (1b) of the support plate (1) projects from the resin sealing body (4), good heat dissipation can be obtained. FIG. 6 shows a fourth embodiment in which two element mounting portions (7) are vertically arranged side by side on a support plate (1) fixed vertically to a wiring board (5) to enable side surface light emission. The semiconductor light emitting device (2) arranged on the upper side of FIG.
The semiconductor light emitting device (2) shown in FIG. 6 has the same structure as the semiconductor light emitting device (2) shown in FIG.
An anode electrode (2a) to which power is supplied from the external lead (9) from the lead thin wire (8a) is formed, and a cathode electrode electrically connected to the support plate (1) is formed on the back surface. Figure 6
Is an example of development to a device for two-color light emission in which a pair of semiconductor light emitting elements (2) share each 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) have different lengths, the external leads can be easily identified. Become.

FIG. 7 shows a fifth embodiment in which a semiconductor light emitting element (2) is arranged on each of two element mounting portions (7) provided in a single recess (1c). The upper semiconductor light emitting device (2) shown in FIG. 7 is provided with an anode electrode (2a) electrically connected to a first external lead (3c) separated through a thin lead wire (8a). It has the same structure as the semiconductor light emitting device (2) shown in (3), and the lower semiconductor light emitting device (2) is electrically connected to the separated first external lead (3d) through the thin lead wire (8a). It has an anode electrode (2a) and has the same structure as the semiconductor light emitting device (2) shown in the lower side of FIG. In the embodiment shown in FIG. 7, two-color semiconductor light emission using each of the first semiconductor light emitting element (2) and the second semiconductor light emitting element (2) mounted on the same element mounting portion (7). Shows the device.

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

In the embodiment shown in FIG. 10, the first semiconductor light emitting element (2) and the second semiconductor light emitting element, which are mounted on independent element mounting portions (7) and also have independent cathode electrodes, are provided.
A two-color semiconductor light emitting device having (2) is shown. FIG. 11 shows that the anode electrodes of the semiconductor light emitting device (2) and the constant voltage diode (14) are separately provided on the first external lead (3c, 3).
Semiconductor light emitting device connected to d) via lead wire (8a)
An eighth embodiment comprising an integrated circuit (15) for controlling or protecting the semiconductor light emitting device (2) and the semiconductor device (2) is shown. When configuring a white semiconductor light emitting device, it is possible to suppress the temperature rise and suppress the deterioration of the semiconductor light emitting element and the phosphor, so that even if operated with a large current, the life becomes long, and with the temperature rise of the phosphor It is also possible to suppress discoloration due to a decrease in the light emitting effect and display a stable color tone.

In the embodiment of the present invention, good heat dissipation can be obtained and the following operational effects can be obtained. [1] Improvement of heat dissipation Support plate having an adhesive portion (1d) serving as a fin exposed to the outside
Since the semiconductor light emitting element (2) is directly bonded to (1), good heat dissipation can be obtained. Further, if the area of the copper foil portion such as the land (10) is expanded as necessary, the heat dissipation can be further improved. [2] Improving productivity If the semiconductor light emitting device (2) is bonded to the support plate (1), for example,
It is possible to manufacture using the current production equipment without requiring a special process including a process of sandwiching the lead in the insulating substrate and an additional component. Since existing equipment can be used without the need for new equipment, there are advantages in terms of productivity and cost. [3] Miniaturization The size of the semiconductor light emitting device is reduced by using the material having good thermal conductivity to reduce the area of the support plate (1), and the semiconductor light emitting device is driven with high current while ensuring heat dissipation. it can. Further, the effect of reducing the area of the wiring board (5) and reducing the number of parts can be expected. [4] Reliability Since the number of parts is smaller than that of the conventional product, 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 drawings]

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

FIG. 2 is a plan view of FIG.

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

FIG. 4 is a plan view of FIG.

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

FIG. 6 is a side view showing a fourth embodiment of a 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 of the present invention.

FIG. 8 is a plan view showing a sixth embodiment of the surface mount semiconductor light emitting device of the present invention.

9 is an electric circuit diagram showing a circuit configuration of the surface mount 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 of the present invention.

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

FIG. 12 is a plan view of a conventional surface mount semiconductor light emitting device.

13 is a side view of the surface mount semiconductor light emitting device shown in FIG.

[Explanation of symbols]

(1) ・ ・ Support (second external lead), (1a) ・ ・ One main surface, (1b) ・ ・ Other main surface, (1c) ・ ・ Concave, (1
d) ・ ・ Adhesive part, (2) ・ ・ Semiconductor light emitting element, (3) ・ ・ First external lead, (3a) ・ ・ Bottom surface, (4) ・ ・ Resin encapsulant, (5) ・ ・ Wiring Substrate, (6) .. gap, (7) .. element mounting part, (8a) .. first fine lead wire, (8b) .. second
Lead thin wire, (9) ・ ・ Third external lead, (9a) ・
・ Bottom,

Continued front page    F-term (reference) 4M109 AA01 BA02 CA21 DA04 DA10                       DB03 DB15 EE12 GA01 GA05                 5F036 AA01 BB16 BC33 BE01                 5F041 AA41 AA43 AA44 AA47 DA03                       DA07 DA43

Claims (5)

[Claims] 1. A support plate, a semiconductor light emitting device fixed to a single or a plurality of device mounting portions provided on one main surface of the support plate, and a semiconductor device arranged at a constant distance from the support plate. And a first electrically connected to the electrode of the semiconductor light emitting device
In the surface mounting type semiconductor light emitting device including the external lead of, and the support plate, the semiconductor light emitting element and a resin sealing body that covers the first external lead, the other flat main surface of the support plate is The first external lead protruding from the bottom surface of the resin sealing body and extending along the edge of the support plate projects from the bottom surface of the resin sealing body in the same direction as the other main surface of the support plate. A surface mount semiconductor light emitting device having a flat bottom surface. 2. The other main surface of the support plate and the bottom surface of the first external lead are arranged on the same plane and are bonded to the land of the wiring board by a conductive adhesive material.
The surface-mounted semiconductor light-emitting device according to. 3. The surface mount semiconductor light emitting device according to claim 1, wherein the support plate and the first external lead are arranged at the same height. 4. The surface mount semiconductor light emitting device according to claim 1, wherein the support plate constitutes a second external lead that is separated from the first external lead. 5. A third external lead, which is electrically connected to the electrode of the semiconductor light emitting device and has the same height as the supporting plate and the first external lead, and a bottom surface of the third external lead. The surface mounting type semiconductor light emitting device according to claim 1, wherein is disposed on the same plane as the other main surface of the support plate and the bottom surface of the first external lead.