JP2012044209A - Light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting device that can stabilize chromaticity, has high resistance against an impact of external force, and has low heat resistance.SOLUTION: A light emission diode chip 24 of a light emitting device is covered by a translucent member 20 which acts as a cover and is formed of rigid resin capable of reducing external force applied to the light emission diode chip and by resin which is used to adjust chromaticity and is softer than the translucent member 20. The translucent member 20 is provided with a resin injection port and an air vent port in the neighborhood of a lens 20-1 which is provided in the light emission direction of the light emission diode chip 24 and configured so as to adjust directivity, and portions other than the resin injection port and the air vent port are configured in a hermetic structure. A container is filled with chromaticity adjusting resin mixed with dye, pigment or fluorescent material injected from the resin injection port, where the chromaticity adjusting resin is solidified in a state that the dye, the pigment or the fluorescent material precipitates in the resin so as to be positionally stabilized at the side of the light emission diode chip 24.

Description

  The present invention relates to a light emitting device used for a lighting device of a display device, a flash of a camera, and the like, and more particularly to an issuing device using a light emitting diode as a light source.

  2. Description of the Related Art In recent years, a light emitting device used for a lighting device of a display device, a flash of a camera, and the like, particularly an issuing device using a light emitting diode (hereinafter abbreviated as LED) as a light source is resin-sealed by potting or transfer molding.

However, in LED light sources, it is common to mix dyes, pigments, or phosphors in the sealing resin, and to correct the chromaticity with the dyes, pigments, or phosphors, so the amount of sealing resin is constant. It is important to stabilize the chromaticity.
However, although the potting method has relatively stable manufacturing equipment, the resin discharge time and discharge pressure are controlled by the machine, so that the amount of resin, that is, the amount of phosphor varies depending on the machine accuracy. In addition, the amount of resin is difficult to control because of the influence of environmental conditions. As a result, it has been difficult to stabilize the chromaticity of the LED light emitting device.

  In addition, if transfer molding is used, the amount of resin can be controlled rather than potting, but there will be restrictions on the resin used, as will be described later, and the investment in manufacturing equipment will increase because the mold is very expensive. In order to use the mold, it is necessary to mix a release agent so that the resin and the mold are not bonded to the resin, the release agent affects the optical characteristics of the light emitting device, A problem arises in that the adhesive strength between the other components of the light emitting device and the transparent resin is weakened.

  Furthermore, it has been pointed out that when an LED chip is mounted on a lead frame and molded by transfer molding, the thickness of the product must be increased (see, for example, paragraph [0007] of Patent Document 1). ).

A second problem is the strength of the sealing resin that protects the LED.
Since the resin is exposed without being covered with a cover or the like in order to output light from the light emitting device, it is easily affected by external force. However, if a high-hardness resin is used to mitigate the influence of external force, it becomes a problem in terms of reliability due to problems such as peeling, and the wire that electrically connects the LED chip during resin sealing is damaged. There is also a tendency to be greatly deformed.

  The third problem is the thermal resistance problem of the light emitting device package. For example, conventional sealing resin such as epoxy hardly radiates heat from the light emitting source, so the heat of the light emitting device rises → VF value decreases → further current There was a risk that it would go into a failure process where the flow of heat goes up and the absolute maximum rating is exceeded and it goes outside the guaranteed range.

There are many suggestions on this issue.
For example, a proposal to mount a LED chip on the metal provided on the back side of the substrate by making a hole in the substrate, improve the heat dissipation characteristics from the LED chip, and at the same time reduce the thickness of the light emitting device and improve the light emission efficiency (For example, refer to Patent Document 1).
However, this proposal does not mention the problem of chromaticity stabilization, which is the first problem, and the problem of sealing resin strength, which is the second problem.

Although basically the same method as in Patent Document 1 is described, there is also a proposal that details a method for making a hole in a substrate and that sealing is preferably performed by transfer molding (see, for example, Patent Document 3). .
Regarding this proposal, it is the same that the first problem is stabilization of chromaticity and the second problem is sealing resin strength.

Furthermore, in a low thermal resistance, thin package, there is also a proposal to stabilize the formula by reducing bubbles during sealing (see, for example, Patent Document 2).
However, this proposal is based on the premise that the chromaticity is stable if there are no bubbles, and the present invention aiming to solve the unstable chromaticity problem even if there are no bubbles and the problem of the influence of external force is the purpose and means Are different.

  Separately, Patent Document 4 discloses a configuration in which a cover 60 is provided on a circuit board 10 on which an LED is mounted, and a capsule 76 is enclosed in the cover, and an opening in which the capsule is opened in the board is disclosed. The structure sealed from the parts 80 and 82 is described.

Japanese Patent No. 3137823 JP 2000-12576 JP 2003-31850 A Special table 2007-535175

  The first problem to be solved is to stabilize the chromaticity of the light emitting device, the second problem is to strengthen against the influence of external force, and the third problem is the first and second problems. It is to realize a light emitting device having a low thermal resistance while solving the above problem.

  The light-emitting device of the present invention includes a base material on which a light-emitting diode chip serving as a light source is mounted, a translucent member made of a resin provided in the light emitting direction of the light-emitting diode chip and having a substantially transparent or diffusing effect. In the light-emitting diode light-emitting device formed with the light-emitting diode chip, the light-emitting diode chip serves as a cover, and the light-transmitting member formed of a hard resin capable of reducing external force on the light-emitting diode chip and the chromaticity softer than the light-transmitting member A lens that is covered with two kinds of resins for adjustment, and that has a resin injection port and an air vent port in the translucent member, and that adjusts the directivity provided in the light emitting direction of the light emitting diode chip The resin injection port and the air vent port are provided in the vicinity of the lens portion, and the resin port and the air vent port are provided. This part has a sealed structure, and the container is filled with a chromaticity adjusting resin mixed with a dye, pigment, or phosphor injected from the resin injection port. The resin is solidified in such a state that a dye, a pigment, or a phosphor is precipitated in the resin so as to stabilize the position on the light emitting diode chip side.

  In the light-emitting device of the present invention, the translucent resin is a resin having a higher refractive index than the chromaticity adjusting resin.

  In the light-emitting device of the present invention, a silicon resin having a refractive index of 1.4 is used as the chromaticity adjusting resin, and an epoxy resin having a refractive index of 1.55 is used as the translucent resin. .

  The light-emitting device of the present invention is characterized in that a hole is formed in the base material, and the light-emitting diode chip is mounted in the hole on a metal base material provided on the back surface of the base material.

  The light-emitting device of the present invention is characterized in that a high heat dissipation block made of metal or ceramic is provided below the metal substrate so as to be in close contact with the metal substrate.

According to the present invention, since the amount of resin for adjusting chromaticity can be made constant, chromaticity can be stabilized with high accuracy.
Moreover, since the viscosity of the resin injected into the container can be lowered, stress can be relaxed and damage to the wire can be reduced.
Furthermore, since it is not a transfer molding method, the influence of the mold release agent can be eliminated, and the mold investment can be reduced.
Furthermore, since the resin component having a relatively high hardness is placed outside the resin for adjusting chromaticity, the resin component having a high hardness works as a cover, and the influence of external force can be reduced.
Further, since the base material is made of metal, high heat dissipation is possible from the metal part of the die bond area, so that the reliability can be improved, the output can be increased, and the size can be reduced.
Furthermore, since the resin for chromaticity adjustment is a resin that remains liquid while the light-emitting device is in operation, the heat of the light-emitting source can be dissipated from the resin part and the metal part of the die bond area by heat flow with high efficiency. As a result, further improvements in reliability and higher output became possible.

It is the figure which showed the 1st Example of the light-emitting device by this invention. FIG. 2 is a cross-sectional view showing a state in which a chromaticity adjusting resin injected into the light emitting device of FIG. 1 is solidified. It is sectional drawing which showed the 2nd Example of the light-emitting device by this invention. It is sectional drawing which showed the example which improved the light utilization efficiency and directivity of 2nd Example. It is sectional drawing when the quantity of resin for chromaticity adjustment differs a little. It is sectional drawing which showed the example in the case of using resin for liquid chromaticity adjustment.

  In the light emitting diode light emitting device, the light emitting diode chip was mounted in a container having a resin injection port and an air vent, and the resin was injected after the light emitting diode chip was mounted in the container. The container includes a base material on which the light emitting diode chip is mounted, and a translucent member provided in the light emitting direction of the light emitting device. The resin is a chromaticity adjusting resin mixed with a dye, pigment or phosphor. A lens for adjusting the directivity of the light emitting device is formed in the light emitting direction of the light emitting device of the light transmissive member.

1A and 1B are views showing a first embodiment of a light emitting device according to the present invention, in which FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line AA ′ of FIG.
In FIG. 1A, 10 is a base material, 12 and 14 are contours of a translucent member provided on the upper part of the light emitting device, 14 is an entire contour, and 12 is a contour of a lens portion. 16 provided on each side of the base material 10 are electrodes connected to the electrodes of the LED chip, and can be operated with a total of at least two electrodes. However, when the power consumption is large, FIG. It is preferable to provide a large number of electrodes as shown. 18 provided in four places are a resin injection port or an air vent, and each may be used for any application.

  In FIG. 1B, the LED chip 24 is die-bonded on the substrate 10, and the electrodes of the LED chip 24 are wire-bonded to the electrodes 22 on the substrate 10 by thin metal wires 26 and are electrically connected. ing. The electrode 22 on the substrate 10 corresponds to the electrode 16 in FIG. 1A. As shown in the drawing, the electrode 22 is routed to the opposite side of the substrate 10, that is, to the back surface of the light emitting device, for example, by a through hole, It has become.

  The translucent member 20 is transparent and made of a resin with relatively high hardness, and the upper surface facing the LED chip 24 is formed in a flat shape. And the lens part 20-1 which adjusts the directivity of a light-emitting device is formed in the center of the flat shape of the translucent member 20 which corresponds to the light emission direction of a light-emitting device. As shown in the figure, a container is formed by the base material 10 on which the LED chip 24 is mainly mounted and the translucent member 20 provided in the light emitting direction of the light emitting device, and the lens unit 20 provided on the translucent member 20 of the container. -1 is provided with a resin inlet 18-1 and an air vent 18-2, and the portions other than the resin inlet and the air vent have a sealed structure. That is, the LED chip 24 is mounted in a container having a resin inlet 18-1 and an air vent 18-2.

After the LED chip 24 is mounted in the container, a chromaticity adjusting resin is injected.
A dye, pigment or phosphor is mixed in the chromaticity adjusting resin, and the chromaticity adjusting resin is injected into the container from the resin injection port 18-1, and the gas or air in the container is discharged from the air outlet. The container is filled while being expelled from 18-2.
Since the injection resin can be selected from very soft ones, damage to the wire such as a wire flow during the resin injection can be reduced, and the stress of the entire light emitting device can be reduced.
In the following drawings, the same members are denoted by the same numbers.

  2 is a cross-sectional view showing a state in which the chromaticity adjusting resin injected into the light emitting device of FIG. 1 is solidified. 2 is different from FIG. 1B in that the chromaticity adjusting resin 28 solidified after injection is illustrated. The injected chromaticity adjusting resin 28 is usually set to have a solidified component, but the dye, pigment, or phosphor 30 mixed in the resin becomes a sink as shown in the figure and the position is stabilized.

  As is clear from FIG. 2, the amount and thickness of the chromaticity adjusting resin 28 are particularly constant in the direction of the lens 20-1 that is the light emitting direction of the light emitting device from the LED chip, and the chromaticity is stabilized. Is remarkable. In such a state, for example, according to the potting method, the amount of resin in the light emitting direction is determined by the surface tension of the resin itself, so that it is difficult to manage the amount of resin, and as a result, the chromaticity varies. Have.

Further, since it is not a transfer molding method, it is not necessary to mix a release agent into the chromaticity adjusting resin 28. Therefore, it is possible to eliminate the possibility that the release agent may affect the optical characteristics of the light emitting device or cause problems such as weakening the adhesive strength between other components of the light emitting device and the transparent resin, and transfer molding. Necessary mold investment can be reduced.
Furthermore, the chromaticity adjusting resin 28 to be injected is made of silicon (refractive index of about 1.4), and the translucent member 20 as a cover having a refractive index higher than 1.4, such as an epoxy lens (refractive index of about 1. 55), when light passes from a material having a refractive index of 1.4 to a material having a refractive index of 1.55, the refraction angle is smaller than the incident angle, so that it is easy to collect light. .

  In FIG. 2, it is important that the upper part of the LED chip 24 is composed of a relatively soft chromaticity adjusting resin 28 and a light-transmitting member 20 which is relatively hard and has a lens portion 20-1 in the center. is there. As described above, since the LED chip 24 is covered with two kinds of resin parts, that is, a relatively soft resin and a relatively hard resin, the hard resin acts as a cover, and the influence of external force on the LED chip 24 is reduced. Damage to the LED chip wire 26 is reduced.

FIG. 3 is a sectional view showing a second embodiment of the light emitting device according to the present invention.
In FIG. 3, the LED chip 24 is die-bonded on a metal substrate 32, and the electrode of the LED chip 24 is wire-bonded to the electrode 22 on the substrate 42 by a wire 26, which is a thin metal wire, and is electrically connected. Has been. That is, the portion where the LED chip 24 is mounted is formed of metal. The electrode 22 on the base material 42 corresponds to the electrode 16 in FIG. 1A, and as shown in the drawing, the electrode 22 is routed to the opposite side of the base material 42, that is, the back surface of the light emitting device by, for example, a through hole. It has become.

The translucent member 20 is made of a transparent and relatively hard resin, and a lens portion 20-1 for adjusting the directivity of the light emitting device is formed at the center corresponding to the light emitting direction of the light emitting device. As shown in the drawing, a container is formed by a metal base 32 on which LED chips are mainly mounted, a translucent member 20 provided in the light emitting direction of the light emitting device, and a base 42, and a resin injection port 18 is formed in the container. -1 and the air vent 18-2 are provided, and portions other than the resin inlet 18-1 and the air vent 18-2 have a sealed structure. That is, the LED chip 24 is mounted in a container having a resin inlet 18-1 and an air vent 18-2.
A portion for mounting the LED chip 24 can be formed by making a hole in the base material 42, and its method is described in detail in Patent Documents 1 and 3.

In order to improve the heat dissipation characteristics, a high heat dissipation block 34 made of, for example, metal or ceramic can be provided below the metal base material 32 in order to improve heat dissipation characteristics.
After the LED chip 24 is mounted in the container, the chromaticity adjusting resin 36 is injected.
The chromaticity adjusting resin 36 is mixed with a dye, pigment, or phosphor, and the chromaticity adjusting resin 36 is injected into the container from the resin injection port 18-1, and gas or air in the container is discharged. The container is filled while being expelled from the air vent 18-2.
Since the upper rigidity as the light emitting device can be secured by the translucent member 20, it is possible to select a very soft injection resin. Therefore, damage to the wire 26 such as a wire flow at the time of resin injection can be reduced, and the stress of the entire light emitting device can be reduced.

With this configuration, the heat dissipation characteristics of the light-emitting device can be improved while maintaining the effects of stabilizing the chromaticity and being strong against the influence of external force described with reference to FIGS.
In a high power consumption light emitting device, it is a big problem that it falls into a failure cycle where heat rises → VF value falls → further current flows → further heat rises and exceeds the absolute maximum rating → out of the guaranteed range It has become.
This problem can be solved by improving the heat dissipation characteristics of the light emitting device, and the effect is great.

  Further, since the LED chip 24 is mounted by making a hole in the base material 42, the height of the translucent member 20 can be lowered, that is, the package height can be lowered to form a thin type. It is.

FIG. 4 is a cross-sectional view showing an example in which the light use efficiency and directivity are improved with respect to the light emitting device of the second embodiment shown in FIG.
FIG. 4 is different from FIG. 3 in a surface 40, which has a gradient so that light emitted from the side surface of the LED chip 24 is reflected upward as shown.
With this configuration, the light emitted from the side surface of the LED chip 24 is emitted upward with a small number of reflections and is easily collected upward, so that the light utilization efficiency and directivity of the light emitting device are improved. The

FIG. 5 is almost the same as FIG. 3, but FIG. 5 (a) shows a case where the amount of the chromaticity adjusting resin is slightly small, and FIG. 5 (b) shows the amount of the chromaticity adjusting resin. It is a figure showing the case where it was a little.
As shown in the figure, even if the amount of the chromaticity adjusting resin is slightly larger, at least the resin shape in the vicinity of the air vent 18-2 is changed to 46 and 48, and the resin amount above the LED chip 24 that is the light emitting direction of the light emitting device is changed. There is no change. Therefore, unlike the potting method, stable chromaticity can be obtained with respect to fluctuations in the amount of chromaticity adjusting resin.
The situation in which the variation in the amount of the chromaticity adjusting resin does not change the amount of the resin in the light emitting direction of the light emitting device is the same as in the first embodiment shown in FIGS. It is.

FIG. 6 is a cross-sectional view as a reference example showing an example in which a liquid resin is used as the chromaticity adjusting resin.
6 is different from FIG. 3 in that the resin inlet 18-1 and the air vent 18-2 are sealed by the resin 52. Since it is sealed, the liquid chromaticity adjusting resin 50 can be used. The chromaticity adjusting resin 50 is a resin whose components are set so as to maintain a liquid state while the light emitting device is in operation.
Fine size dyes, pigments, or phosphors are adjusted to convection with the resin while being uniformly dispersed even when thermal convection occurs. Large size phosphors precipitate even when thermal convection occurs. It is adjusted so that it will not convection with the resin.

Since the liquid resin is used as described above, the resin can flow by convection due to heat generation, and the resin is not easily discolored by the ultraviolet rays from the blue element, and there is an effect of preventing deterioration with time.
In addition, since the dyes, pigments, or phosphors are uniformly dispersed, there is an effect that the balance of emission color is good.
Furthermore, when the recess is formed on the substrate, the phosphor is precipitated, and the phosphor tends to concentrate in the vicinity of the LED element in the recess, so that there is an effect that the conversion efficiency is good.
Furthermore, when a gel-like resin is added to the resin, the dye, pigment or phosphor in the resin can be dispersed more uniformly.

  When the liquid chromaticity adjusting resin can be used in this manner, heat from the LED chip 24 that is a light emitting source is dissipated by the thermal flow of the liquid resin, and the heat dissipation characteristics of the light emitting device package are remarkably improved. Therefore, reliability is also improved. Further, since the liquid resin is very soft, the stress applied to the light emitting device is relieved, and the damage to the wire can be very small.

24 Light-Emitting Diode Chip 30 Dye or Pigment or Phosphor 18-1 Resin Injection Port 18-2 Air Vent 26, 32 Base Material 20 Translucent Member 28, 36, 46, 50 Chromaticity Adjustment Resin 20-1 Lens

Claims (5)

Light-emitting diode light-emitting device having a container formed of a base material on which a light-emitting diode chip serving as a light source is mounted, a translucent member made of a resin provided in the light emitting direction of the light-emitting diode chip and having a substantially transparent or diffusing effect In
The light emitting diode chip functions as a cover, and is made of two kinds of resins, the light transmitting member formed of a hard resin capable of reducing the external force applied to the light emitting diode chip and the chromaticity adjusting resin softer than the light transmitting member. The translucent member is formed with a resin injection port and an air vent and a lens for adjusting directivity provided in the light emitting direction of the light emitting diode chip. The resin injection port and the air vent are provided in the vicinity of the container, and the portions other than the resin injection port and the air vent have a sealed structure. Filled with chromaticity adjusting resin mixed with injected dye, pigment or phosphor, and the chromaticity adjusting resin is dye, pigment or phosphor in the resin The light emitting device characterized in that positioned in the light emitting diode chip side is solidified in a state of being precipitated to be stable.   The light emitting device according to claim 1, wherein the translucent resin is a resin having a higher refractive index than the chromaticity adjusting resin.   The light emitting device according to claim 2, wherein a silicon resin having a refractive index of 1.4 is used as the chromaticity adjusting resin, and an epoxy resin having a refractive index of 1.55 is used as the translucent resin. .   The hole is formed in the said base material, The said light emitting diode chip is mounted in the said hole on the metal base material provided in the back surface of the said base material, The Claim 1 thru | or 3 characterized by the above-mentioned. The light-emitting device of description. The light emitting device according to claim 4, wherein a high heat dissipation block made of metal or ceramic is provided below the metal base material so as to be in close contact with the metal base material.

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