JPH05251485A - Method of forming lens of light emitting device - Google Patents

Abstract

PURPOSE:To make highly compatible with mass production and enable o maintain high reliability and beside make easy to cope with specification change by adjusting the pressure adjusting valve inside a resin supply passage, and injecting the liquid-form translucent resin into the resin of the mold on a substrate by injection method, and forming a plurality of condensing lenses at the same time. CONSTITUTION:An LED 12 is die-bonded on the cavity 11a of a substrate 11, and is connected by a bonding wire 13. Next, for translucent resin 14, epoxy resin is used. A main agent and a hardener are counted by specified amounts, and after mixing, it is defoamed. Next, by a temperature adjuster, the temperature of a mold is set in the specified range of 100 deg.C-200 deg.C. Then, a mold releasing agent is applied after cleaning the inside of the mold such as a recess 22, etc. Next, the substrate 11, where the LED is mounted, is set in the mold 21. Next, a pressure adjusting valve 24 is closed after clamping upper and lower molds 21a and 21b, and liquid-form translucent resin 14 is injected and is hardened. Hereby, it can cope with the change of a mold merely by adjusting the injection pressure with the pressure adjusting valve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of molding a lens for a light emitting device in the shape of a doughnut-rice used for a display panel or the like, and more particularly to a method of molding a lens for a light emitting device which is inexpensive and highly reliable.

[0002]

2. Description of the Related Art The conventional light emitting devices such as Dot Tomato Rix used as a display panel are as follows.

(Prior art example 1) A light emitting element (LED) is mounted on a vertical lead frame, and a resin-molded light emitting element, that is, an LED lamp is simply mounted on a substrate in a solder-like shape.

(Conventional example 2) LE is mounted on a resin-molded case.
A substrate having a D (chip-on-board: hereinafter referred to as COB), which has been injected and cured with a liquid translucent resin and has no lens.

(Prior Art Example 3) A lens-shaped mold is obtained by injecting a liquid translucent resin such as epoxy resin into a lens-shaped mold, inserting COB, and curing the resin.

(Prior art example 4) A hollow transparent resin molded separately into a lens shape and covering the COB.

(Conventional Example 5) As shown in FIGS. 7 and 8, a lens is sealed on the COB by a transfer molding using a transparent resin. In the figure, 1 is an upper mold, 2 is a lower mold, 3 is a resin mass (tablet) which exhibits fluidity (even temporarily) by heating B-staged translucent resin, etc., 4 is a resin injection hole, 5 Is a high-pressure molding machine for pushing the transparent resin block 3 in the resin injection hole into the mold. Here, both molds 1 and 2 are about 10
They are pressed against each other at a high pressure of 0t, and the high-pressure molding machine 5
Presses the transparent resin block 3 with a force of about 1 t.

[0008]

In the prior art example 1, since a large number of LED lamps are mounted on the substrate by soldering, the number of manufacturing steps increases, which leads to an increase in defective items such as soldering defects, which is not suitable for mass production.

Further, in order to obtain brightness as an outdoor dot matrix display plate, it is necessary to provide the LED with a lens, but in the conventional example 2, the lens shape cannot be obtained and high brightness cannot be achieved.

In the conventional examples 2 and 3, COB is manually produced.
Air bubbles are often involved when inserting into the mold. In order to avoid this, it is conceivable to add a diluent to the translucent resin to further reduce the viscosity, but if this is done, the properties such as water resistance and heat resistance of the resin will deteriorate.

In the conventional example 3, when a resin mold is used as the lens-shaped mold, it is necessary to frequently replace the mold due to the life of the resin material. In addition, the cost of using the mold,
There are many wastes in terms of handling. It takes 1 hour or more to remove from the mold, and if this is combined with the secondary curing time after removing from the mold, the curing time as a whole becomes long.

In Conventional Example 4, since the lens has a hollow shape, when this is used outdoors, there is a problem in durability such as oxidation and corrosion due to water entering inside.

In the transfer molding method of Conventional Example 5, since it is difficult to control the fluidity in the mold as the light-transmitting resin block 3, a plurality of devices arranged in a matrix form are resin-sealed. In that case, problems such as unfilling and bubbles are likely to occur. To avoid this, the substrate size must be limited.

When a plurality of COBs are simultaneously inserted into the molds 1 and 2 and sealed with resin, the number of sets of substrates (hereinafter referred to as the number of lots) is determined by the work size and lens shape (resin amount). However, when it is desired to change the number of lots, the lens shape, etc., as shown in FIGS. 7 and 8, it is necessary to spread the resin over all devices. There is no choice but to change the molding conditions such as the viscosity of the resin itself on a large scale, and the items to be managed as molding conditions are preheating conditions, resin injection pressure, mold temperature, cure time, mold clamping pressure, plunger slow point. Since the position, the resin injection time, the plunger heater temperature, and the like are complicated in various ways, mass productivity deteriorates. In addition, the transfer molding method requires a large size of equipment such as a mold and a high-pressure molding machine and is very expensive. Therefore, a slight change in specifications such as a change in the mold causes a large cost.

In view of the above problems, it is an object of the present invention to provide a method for molding a lens of a light emitting device which is inexpensive, rich in mass productivity, capable of maintaining high reliability, and easy to cope with specification changes.

[0016]

According to the means for solving the problems according to the present invention, a substrate 11 on which a plurality of light emitting elements 12 are mounted is inserted into a mold 21 having a plurality of recesses 22 for forming a lens, and a resin supply path is provided. The pressure adjusting valve 24 in 23 is adjusted to inject the liquid translucent resin 14 into the recess 22 of the mold 21 on the substrate 11 by the injection method to form a plurality of condenser lenses 15 at the same time. It is a thing.

[0017]

In the above means for solving the problems, when molding a plurality of devices, the substrate 11 is inserted into the mold 21, and the liquid translucent resin 14 is injected into the recess 22 of the mold 21 by the injection method. The condenser lens 15 is formed.

If it is desired to change the number of devices such as the number of devices, the shape of the condenser lens 15, or the like, the transparent resin 14 is used.
Since the liquid is liquid, the transparent resin 14 can be spread over the entire surface of the mold 21 only by adjusting the injection pressure of the pressure adjusting valve 24, and the design change of the light emitting device becomes easy.

[0019]

FIG. 1 is a schematic view showing a lens forming method of a light emitting device according to an embodiment of the present invention, and FIG. 2 is an overall perspective view of the light emitting device.
3 is a perspective view showing one device of the light emitting device, FIG. 4 is a sectional view of the light emitting device, and FIG. 5 is a process drawing from resin injection to completion.

As shown in the figure, the light emitting device of this embodiment is used for an electronic bulletin board or the like for outdoor display.
1, a plurality of recesses 11a are formed in a dot matrix shape, a light emitting element 12 (hereinafter, referred to as an LED) is mounted on each recess 11a, and the LED 12 is bonded to a wiring pattern (not shown). Is connected with
Around each LED 12 and bonding wire 13,
A parabola-shaped condenser lens 15 is formed of the translucent resin 14.

The substrate 11 is made of a glass epoxy resin, a heat-resistant engineering plastic, or a metal substrate such as aluminum. If the recess 11a is formed in a parabolic shape, the brightness can be expected to improve due to the reflection effect. The substrate size and the number of matrix dots are determined according to the application. When the lens is molded, the substrate 11
Is the work size and lens shape (that is, the required resin amount)
In consideration of the above, a plurality of rice sheets are arranged side by side and inserted into a mold 21 described later, and these are simultaneously sealed with resin.

The translucent resin 14 is mainly composed of a raw epoxy resin (hereinafter referred to as a main component) and a fixed amount of additives such as a curing agent, a curing accelerator, an anti-yellowing agent and an ultraviolet absorber. Stuff used.

The mold 21 used in this embodiment is composed of an upper mold 21a and a lower mold 21b.
A concave portion 22 for forming the condenser lens 15 is formed in each device 1a for each device, and a temperature adjusting device (not shown) for adjusting the mold molding temperature is provided.

The mold 21 is provided therein with an injection device M for injecting the liquid translucent resin 14 by the injection method. The injection device M is provided with a tank 25 for storing the liquid translucent resin 14 and a pressurizer 26 for pressurizing the translucent resin 14 in the tank 25.

Between the injection device M and the mold 21,
They are connected by a resin supply path 23 for supplying the translucent resin 14. The resin supply passage 23 is provided with a pressure adjusting valve 24 for adjusting the injection pressure of the transparent resin 14.

The light emitting device of this embodiment is manufactured as follows.

The LED 12 is die-bonded on the recess 11a of the substrate 11 and connected by the bonding wire 13.

An epoxy resin is used as the liquid translucent resin 14. Measure a prescribed amount of main agent and curing agent,
After mixing, degas. A coloring agent or a scattering agent may be added depending on the application. The temperature of the mold is poured into the tank 25, and the mold temperature is set to 100 ° C to 200 ° C.
Set within the predetermined range of. Depending on the case, the temperatures of the upper mold and the lower mold may be changed. After that, after cleaning the inside of the mold such as the recesses 22, a mold release agent is applied.

The substrate 11 (hereinafter referred to as COB) on which the LED 12 is mounted is set in the mold 21. Here, in order to increase the number of lots and increase the manufacturing efficiency, a plurality of COBs 11 may be inserted at the same time.

After tightening the upper and lower molds 21a and 21b, the pressure adjusting valve 24 is opened and the liquid translucent resin 14 is injected and cured. Then, since the translucent resin 14 is in a liquid state, it becomes easy to spread the resin to all the recesses 22 in the mold 21. Regarding the generation of bubbles, it is desirable to make the inside of the mold 21 a vacuum state in some cases.

By the above method, the following merits can be desired.

(1) In this embodiment, since the condenser lens 15 is molded by applying a constant pressure to the liquid epoxy resin, the unfilled state and bubble generation which are problems in the conventional examples 3 and 5, Since the resin easily spreads throughout the mold,
There is no need to consider it as a molding condition. Therefore,
The molding conditions are extremely easy to control.

(2) In the present embodiment, the resin curing time (mold release time) varies slightly depending on the amount of resin, that is, the size of the condenser lens 15, but as shown in FIG. It can be greatly shortened compared to 2, 3, 5. In addition, in FIG. 5, (a) is a die vacuuming time, which requires some time. Further, (B) shows the time for which the pressure regulating valve 24 is in the open state, which changes 2-3 times depending on the amount of resin, but in any case, it only takes a few minutes.

(3) In this embodiment, by directly molding the condenser lens 15 on the substrate 11 on which the LED 12 is mounted, the number of steps can be shortened as compared with the conventional example 4 in which individually molded lenses must be attached to the substrate. ..

(4) According to the infusion method as in this embodiment, since the molding can be performed at a low pressure, the apparatus becomes inexpensive. Here, comparing with transfer molding,
The resin injection pressure is 1 kg, which is lower than 1 ton of Conventional Example 5. Therefore, for example, in the case of transfer molding as in Conventional Example 5, even a trial mold needs about 100 million yen, but in the present embodiment, the mold is more than 100,000 yen. Can be created. As a result, the product as a technical sample has a great deal of applicability, such as lens-shaped optical investigations.

(5) The shape of the condenser lens 15 may be changed as shown in FIG. 6 or the number of lots may be changed depending on the circumstances such as shipping. At this time, in this embodiment, since molding is performed from a liquid epoxy resin, the mold temperature of the temperature adjusting device, the resin injection pressure of the pressure adjusting valve 24, and the molding are items that must be controlled and changed as environmental conditions. It is only necessary to adjust the time, and it is not necessary to change the pressing force of the large-sized device as shown in FIGS.

(6) Since the liquid resin is used as it is as compared with the transfer molding resin as in Conventional Example 5, it is easy to change and develop the resin material such as improving the resin characteristics.

The present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

For example, the injection device M may be provided with a device for automatically measuring, mixing, defoaming, etc. directly connected to the tank 25.

[0040]

As is apparent from the above, in the present invention, the condensing lenses of a plurality of devices are injection-molded with a liquid translucent resin by the injection method. When used in a method,
Unfilling and bubble generation can be easily prevented, high reliability can be maintained, molding conditions can be managed very easily, molding time can be shortened, and the cost of the apparatus can be reduced. Therefore, the mass productivity can be improved, the lens type prototype can be made inexpensive, and the optical examination can be easily performed.

Further, when it is desired to change the number of lots or the shape of the condenser lens due to the circumstances such as shipping, since liquid resin is used as the injection resin, it is possible to adjust the pressure of the pressure adjusting valve a little. It is easy to spread the resin to all devices. Therefore, there are few items that need to be changed and managed as environmental conditions, and when the cost for design change is reduced, an excellent effect can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a lens molding method of a light emitting device according to an embodiment of the present invention.

FIG. 2 is an overall perspective view of a light emitting device

FIG. 3 is a perspective view showing one device of a light emitting device.

FIG. 4 is a sectional view of a light emitting device.

[Figure 5] Process diagram from resin injection to completion

FIG. 6 is a sectional view of a light emitting device in which the shape of a condenser lens is changed.

FIG. 7 is a schematic diagram showing a resin injection operation in a transfer method of a conventional light emitting device.

FIG. 8 is a schematic diagram showing a resin pressing operation in a transfer method of a conventional light emitting device.

[Explanation of symbols]

 11 Substrate 14 Translucent Resin 15 Condensing Lens 21 Mold 22 Recess 23 Resin Supply Channel 24 Pressure Control Valve

Claims (1)

[Claims] 1. A mold on which a substrate on which a plurality of light emitting elements are mounted is inserted into a mold having a plurality of recesses for forming a lens, and a pressure control valve in a resin supply path is adjusted, A lens molding method for a light emitting device, characterized in that a liquid translucent resin is injected into the recess by an injection method to form a plurality of condenser lenses at the same time.