JP3723328B2 - Semiconductor light emitting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor light emitting element provided with a protective element. More specifically, a protective element is provided to prevent the light emitting element from being damaged by static electricity even when a reverse voltage or a forward voltage higher than a predetermined voltage is applied to the light emitting element due to AC voltage driving or static electricity. The present invention relates to a semiconductor light emitting device.
[0002]
[Prior art]
Conventionally, a semiconductor light emitting device is configured by forming a pn junction by directly joining a p-type layer and an n-type layer, or by forming a double heterojunction by sandwiching an active layer between the p-type layer and the n-type layer. When a forward voltage is applied to the shape layer, light is emitted from the pn junction or the active layer. For example, as shown in FIG. 4, a light emitting element chip (hereinafter referred to as an LED chip) 3 made of a semiconductor laminate is bonded to the tip of a first lead 1 and one electrode is One lead 1 is electrically connected, and the other electrode is electrically connected to the second lead 2 by a gold wire 4 or the like, and its periphery is covered with a resin package 6 that is transparent to the light of the LED chip 3. Is formed.
[0003]
Since such a light emitting element has a diode structure, an AC voltage is applied without applying a DC voltage between both electrodes by using a rectifying action in which no current flows even when a reverse voltage is applied. Accordingly, a method of using light that emits light when a current flows only when a forward voltage is generated by alternating current is also employed.
[0004]
[Problems to be solved by the invention]
In general, compound semiconductors such as GaAs, GaP, and gallium nitride are generally used for semiconductor light emitting devices, but when these compound semiconductors are used, they are weak against a voltage applied in the reverse direction. The semiconductor layer may be destroyed. In particular, gallium nitride-based compound semiconductors have a breakdown voltage in the reverse direction as low as about 50 V, and are particularly susceptible to breakdown with respect to an applied voltage in the reverse direction. Since the operating voltage is higher than that of the device, there is a problem in that the semiconductor light emitting device is damaged or its characteristics are deteriorated by application of an AC voltage.
[0005]
Further, even when driving is not performed by applying an AC voltage, when a large voltage such as a surge voltage is applied from the outside, there is a problem that a gallium nitride compound semiconductor is easily broken even at a forward voltage of about 150V.
[0006]
In order to prevent breakdown due to application of reverse voltage or static electricity, a Zener diode may be incorporated in the circuit in which the semiconductor light emitting element is incorporated in parallel with the semiconductor light emitting element in the opposite direction to the semiconductor light emitting element. . However, there is a need for space and man-hours to break down by static electricity during handling such as manufacturing process before being built into the circuit, transport process accompanying shipment, or when being built into the circuit board, or to incorporate diodes other than LEDs in the external circuit There is a problem that.
[0007]
The present invention has been made to solve such problems. Even if static electricity is applied during the manufacturing process, the transporting process, or the handling such as mounting on a circuit board, the reverse voltage due to the AC driving or the like is also provided. It is an object of the present invention to provide a semiconductor light emitting device that is less likely to be damaged or destroyed even when a voltage is applied, and that hardly affects the performance and manufacturing cost of a conventional light emitting device.
[0008]
[Means for Solving the Problems]
The semiconductor light emitting device according to the present invention includes a first lead having a curved concave portion formed at one end thereof, a second lead provided in parallel with the first lead, and a concave portion of the first lead. A light-emitting element chip die-bonded to the light-emitting element, connection means for electrically connecting two electrodes of the light-emitting element chip to the first and second leads, respectively, and between the juxtaposed first and second leads And a protective element bonded so that the two electrodes are directly electrically connected to each other, and the protective element protects the light emitting element chip against at least a reverse voltage that can be applied to the light emitting element chip. It is composed of elements.
[0009]
Here, the protective element means an element that can short-circuit a reverse voltage that can be applied to the light-emitting element chip, or can short-circuit a forward voltage that is higher than a predetermined voltage that is higher than the operating voltage of the light-emitting element chip. It includes a diode connection of a transistor, a device in which a gate and a source or drain of a MOSFET are short-circuited, or a composite device thereof, an IC, or the like. The connecting means means means that can be connected by a gold wire or a conductive adhesive. Further, the direct electrical connection of the electrodes means that the electrodes are connected by contact or a conductive adhesive without using a wire such as a gold wire.
[0010]
With this structure, since the protective element is sandwiched and bonded between the leads constituting the light emitting element, there is no need for wire bonding and no space for mounting the protective element is required. Therefore, the light emitting portion side is formed with the same structure as the conventional one, and the light emission characteristics are not affected at all, and the cost is not increased, and a lamp-type semiconductor light emitting element incorporating a protection element can be easily obtained.
[0011]
A protruding portion is provided on a side wall of one of the first and second leads facing each other, and the protection element is bonded between the protruding portion and the other of the first and second leads. As a result, the protective element can be mounted more easily and reliably.
[0012]
If the light-emitting element chip is made of a gallium nitride compound semiconductor and the protection element is a Zener diode, a semiconductor that uses a gallium nitride compound semiconductor that is particularly weak against reverse voltage and weak against high voltage application in the forward direction. In a light emitting element, it is preferable because it is protected against application of reverse voltage or surge voltage. In particular, by using a Zener diode as a protective element, even if a high voltage such as a surge is applied to the light emitting element chip in the forward direction, the Zener diode is protected without damaging the light emitting element chip, There is no abnormality in normal operation. Here, the gallium nitride compound semiconductor is a compound in which a group III element Ga and a group V element N or a part of the group III element Ga is substituted with another group III element such as Al or In, and A semiconductor composed of a compound in which a part of N of the group V element is substituted with another group V element such as P or As.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, the semiconductor light emitting device of the present invention will be described with reference to the drawings.
[0014]
The semiconductor light-emitting device of the present invention has first and second leads 1 and 2 juxtaposed, as shown in FIG. A curved concave portion 11 is formed on the surface. The LED chip 3 is bonded in the recess 11, one electrode of the LED chip 3, for example, the n-side electrode is electrically connected to the first lead 1, and the other electrode, for example, the p-side electrode is the second electrode. The lead 2 and the gold wire 4 are electrically connected by connecting means. In the example shown in FIG. 1, a tongue piece 12 is provided on the side wall of the first lead 1 facing the second lead 2, and the protective element is directly provided between the tongue piece 12 and the second lead 2. The electrodes of the Zener diode 5 are connected, and are electrically connected between the first and second leads 1 and 2 so as to be opposite to the LED chip 3. And the periphery is covered with the resin package 6.
[0015]
The first and second leads 1 and 2 are punched by punching a plate made of iron or copper and having a thickness of about 0.4 to 0.5 mm, and a conical punch is formed from the top of the first lead 1. By stamping with a method such as the above, a bowl-shaped recess 11 is formed at the tip. When punching out from this plate-like body, as shown in FIG. 1, a tip 12 is formed with a thin tip and protruding obliquely, and a gap between the tongue 12 and the second lead 2 is described later. Use a mold with a shape that is slightly smaller at the tip of the tongue 12 and slightly larger at the root of the tongue 12 than the thickness of the diode 5 (the distance between the positive and negative electrodes provided on both sides). To form. That is, in the example shown in FIG. 1, the portion of the second lead 2 facing the tongue piece 12 is punched into a shape that approaches the tongue piece 12. The tongue pieces 12 and the second leads 2 can be easily formed into arbitrary shapes simply by changing the mold shape. As a result, since the tongue piece 12 has a spring property that bends the tip portion toward the gap with the first lead 1, the Zener diode 5 is inserted into the gap with the second lead 2 from the root side of the tongue piece 12. By doing so, it can be easily inserted and fixed securely. In the manufacturing stage, the lower ends of the first and second leads 1 and 2 are connected by a frame portion of the lead frame.
[0016]
The LED chip 3 is formed, for example, as shown in FIG. 2 in a cross-sectional view of a chip having a blue-based (ultraviolet to yellow) emission color. That is, for example, on the surface of the substrate 31 made of sapphire (Al ₂ O ₃ single crystal) or the like, the low-temperature buffer layer 32 made of GaN is about 0.01 to 0.2 μm, and the n-type layer 33 that becomes the cladding layer is 1 to 5 μm. The active layer 34 made of an InGaN-based compound semiconductor (meaning that the ratio of In and Ga can be changed variously, the same applies hereinafter) compound semiconductor is about 0.05 to 0.3 μm, p-type AlGaN-based (ratio of Al to Ga) P-type layer (cladding layer) 35 composed of a compound semiconductor layer 35a and a GaN layer 35b is sequentially stacked in a thickness of about 0.2 to 1 μm, and a current diffusion layer is formed on the surface thereof. A p-side electrode 38 is formed via 37. Further, the n-side electrode 39 is provided on the n-type layer 33 exposed by removing a part of the stacked semiconductor layers 33 to 35.
[0017]
The Zener diode chip 5 is made of a normal silicon semiconductor or the like, and utilizes a phenomenon in which electrons flow through the pn junction by a tunnel effect when a large reverse voltage is applied to a pn junction of a semiconductor having a high impurity concentration. The voltage at which the reverse current starts to flow (zener voltage) is set by the impurity concentration. Therefore, the Zener voltage is set to a predetermined voltage higher than the operating voltage of the LED chip 3, and the first and second leads 1, so that the LED chip 3 and the Zener diode chip 5 are in parallel and in opposite directions. By connecting to 2, the operation of the LED chip 3 is not hindered.
[0018]
As shown in FIG. 1, the LED chip 3 is bonded to the concave portion 11 of the first lead 1 with an adhesive such as silver paste. As described above, the n-side electrode 39 and the p-side electrode 38 of the LED chip 3 are bonded. 2 (see FIG. 2) are connected to the first lead 1 and the second lead 2 by the gold wire 4 and are electrically connected. Further, the Zener diode chip 5 has its positive electrode in contact with the tongue 12 of the first lead 1 and its negative electrode in contact with the second lead 2. A conductive adhesive such as silver paste is applied to the opposite portion of the lead 2 and inserted from the base side of the tongue piece 12. As a result, the tip end side of the tongue piece 12 is pushed and inserted into the first lead 1 side, the Zener diode chip 5 is sandwiched by its spring property, and the conductive adhesive is solidified, whereby the Zener diode chip 5 is The first and second leads 1 and 2 are electrically connected and firmly fixed. If the LED chip 3 has a structure in which an n-side electrode and a p-side electrode are provided on both upper and lower surfaces, one electrode needs to be wire-bonded by die-bonding the LED chip with a conductive adhesive. There is no electrical connection. Then, the semiconductor light emitting device of the present invention covered with the resin package 6 is formed by molding the periphery including the Zener diode chip 5 with a transparent or milky white epoxy resin that transmits light emitted from the LED chip 3. Is obtained. As shown in FIG. 1, the resin package 6 is formed in a dome shape so that the light emitting surface side is a convex lens, whereby a lamp-type light emitting element is obtained.
[0019]
According to the semiconductor light emitting device of the present invention, a Zener diode chip is incorporated, and as shown in an equivalent circuit diagram in FIG. 3, the Zener diode chip 5 has a polarity in parallel with the LED chip 3. And are connected so as to be reversed. Therefore, even if the power source for driving the LED chip 3 is an AC power source, the Zener diode chip 5 has a reverse voltage lower than the Zener voltage when the LED chip 3 has a phase that becomes a forward voltage. No current flows, and current flows through the LED chip 3 to emit light. Further, when the AC power supply has a phase in which the reverse voltage is applied to the LED chip 3, a current flows through the Zener diode chip 5. Therefore, even when the AC voltage is in the reverse voltage phase with respect to the LED chip 3, the reverse voltage is hardly applied to the LED chip 3. In addition, when static electricity is applied, if the static electricity is in the reverse direction of the LED chip 3, it is discharged through the Zener diode chip 5, and in the forward direction to the LED chip 3, if the voltage is higher than the Zener voltage, the Zener is discharged. The LED chip 3 is protected to discharge through the diode chip 5, and if it is lower than the Zener voltage, it is discharged through the LED chip 3. However, since the voltage is low, the LED chip 3 is not damaged. As a result, even if the LED chip 3 is weak against reverse voltage or electrostatic surge, a high voltage is not applied to the LED chip 3, and the LED chip 3 is not damaged or deteriorated.
[0020]
On the other hand, in the semiconductor light emitting device of the present invention, since the Zener diode chip 5 is directly bonded between the first and second leads 1 and 2, a space for mounting the Zener diode 5 around the LED chip 3 is provided. The Zener diode chip 5 can be built in without requiring any change on the light emitting unit side. Moreover, since the Zener diode chip 5 is sandwiched and electrically connected between the two leads, there is no need for wire bonding, so that the manufacturing process is hardly increased and the reliability of the wire bonding is improved. Sexual problems do not occur. As a result, a semiconductor light-emitting element incorporating a protective element can be obtained without increasing costs or reducing light emission characteristics.
[0021]
In the above example, a Zener diode chip is used as the protective element, but a packaged product may be used instead of the chip. Moreover, even if it is not a Zener diode but a normal diode, it can protect with respect to the voltage of the reverse direction with respect to a LED chip. Furthermore, even if it is not a diode, a diode such as a diode-connected transistor, a MOSFET gate connected to a source or drain, or a composite element or IC that combines these to protect in both directions like a Zener diode Any element can be used as long as it can protect the LED chip.
[0022]
In the above-described example, a blue semiconductor light emitting device using a gallium nitride compound semiconductor as a light emitting device is used. However, a gallium nitride compound semiconductor is particularly easily broken by a reverse voltage or a high voltage. Great effect. However, the present invention is not limited to this, and red and green light emitting elements such as GaAs, AlGaAs, AlGaInP, and InP are also protected against reverse voltage and static electricity by providing protective elements. In contrast, a strong semiconductor light emitting device can be obtained.
[0023]
Further, in the above-described example, the tongue piece 12 is provided on the first lead 1 and the shape of the second lead 2 is made to approach the portion facing the tongue piece. However, the tongue piece is formed on the second lead 2 side. The first lead and the second lead may be reversed, and the second lead 2 is formed so that the distance between the leads coincides with the distance between the protective elements, even if the shape of the second lead 2 is not made close. It only has to be done. Further, even if it is not a tongue piece, a protruding portion having another shape such as an arc shape in cross section may be provided, or the protruding portion is not formed at all and the distance between the two leads directly matches the interval of the protective element. It may be formed.
[0024]
【The invention's effect】
According to the present invention, since the protective element is directly mounted between the two leads constituting the light emitting element, there is no need for wire bonding, the manufacturing man-hours are increased, and the element size is not increased. A semiconductor light-emitting element incorporating a protection element can be obtained without causing any change on the side. As a result, there is no damage even when reverse voltage is applied or high voltage is applied due to static electricity, and reliability is greatly improved. There is no need to pay special attention to removal, and work efficiency is greatly improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional explanatory view of an embodiment of a semiconductor light emitting device of the present invention.
2 is a cross-sectional explanatory diagram of an example of the LED chip of FIG. 1;
3 is an equivalent circuit diagram of a connection relationship of the semiconductor light emitting device of FIG. 1. FIG.
FIG. 4 is a perspective explanatory view of an example of a conventional semiconductor light emitting element.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 1st lead 2 2nd lead 3 LED chip 4 Gold wire 5 Zener diode chip

Claims (2)

A first lead having a curved recess formed at one end thereof, a second lead provided in parallel with the first lead, and a light emitting element chip die-bonded in the recess of the first lead Connecting means for electrically connecting the two electrodes of the light-emitting element chip with the first and second leads, respectively, and two electrodes are directly connected between the juxtaposed first and second leads, respectively. A semiconductor light emitting device comprising a protective element bonded so as to be connected to the light emitting element, the protective element protecting the light emitting element chip against at least a reverse voltage that can be applied to the light emitting element chip. A protrusion is provided on a side wall of one of the first and second leads facing each other, and the protection element is bonded between the protrusion and the other of the first and second leads. The semiconductor light emitting device according to claim 1.

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