JPH0440870B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of resin-sealing a light emitting diode provided at the tip of a metal frame using injection molding.

(Conventional technology) Generally, light emitting diodes (hereinafter referred to as LEDs)
Resin sealing is performed using a cast molding method.

This method heats and melts a thermosetting resin such as epoxy resin and injects it into a pot-shaped mold, then inserts the tip of a metal frame on which the LED has been die-bonded and wire-bonded into the resin, and while maintaining that state. This required a multi-step process of heating and curing the resin in a furnace and then releasing the resin from the mold to obtain a product.

The cast molding method described above has a long curing time, requiring approximately 24 hours to complete the entire process, resulting in poor productivity. Requires large-scale equipment.

Furthermore, with this molding method, almost no pressure is applied to the resin, so dimensional accuracy is poor, air tends to get trapped when inserting the metal frame, and it is difficult to keep the metal frame centered, resulting in eccentricity. I had an easy problem.

Therefore, attempts have recently been made to insert a metal frame into a mold using injection molding, inject and fill the cavity with resin, and seal the LED with resin.

(Problem to be solved by the invention) However, in injection molding, resin is filled at a higher speed and pressure than in cast molding. (φ0.02mm) may break.
However, when injection is performed at low speed and low pressure, there is a problem that molding defects such as flow marks and weld lines occur, resulting in poor yield and making it difficult to use for mass production.

This invention was devised to solve the problems caused by the above-mentioned cast molding method and injection molding method. The object of the present invention is to provide a new resin sealing method that is less likely to cause flow marks, weld lines, etc.

(Means for Solving the Problems) The present invention according to the above-mentioned object is to encapsulate a light emitting diode chip, which has been die-bonded and wire-bonded to the tip of the metal frame, with a resin. It is inserted into a mold having a cavity smaller than the finished dimensions, and the cavity is filled with the first resin at low injection speed and pressure to form a primary sealing body that encloses the chip and wire together with the tip of the metal frame. The metal frame is then transferred to another mold, the tip is inserted into the finishing cavity together with the primary sealing body, and the second mold is molded.
The above-mentioned problems are solved by filling the resin at high injection speed and pressure to form a secondary sealing body.

(Function) In the above configuration, during primary molding, the mold is first sealed with a cavity smaller than the finished size, and then transferred to a cavity with the finished size for secondary molding, where secondary sealing is performed and the final size is finished.

Since the primary sealing part has a small volume and a short resin flow length, the wire will not break even if it is filled at high speed and pressure compared to conventional injection molding. In addition, secondary molding allows filling at high speed and high pressure without worrying about wire breakage, resulting in highly accurate molded products.

The present invention will be explained in detail below with reference to illustrated examples.

(Example) In the figure, 1 is a pair of metal frames formed parallel to each other, an LED chip 2 is die-bonded to the tip of one frame, and a wire 3 is bonded to the tip of the other frame and the chip 2. It has been done.

As shown in FIG. 1, this metal frame 1 is
Insert into a mold 11 having a cavity 10 smaller than the finished dimension, and insert the tip 2 together with the tip.
and position the wire 3 in the cavity 10.

Next, the mold 11 is closed and clamped, and a thermoplastic resin such as polycarbonate, acrylic resin, or polymethylpentene is filled as the first resin at low injection speed and pressure, and the chips 2 and wires 3
A sealing body 4 is formed to temporarily enclose the frame together with the frame tip.

Once this primary sealing is completed, the mold is opened and the metal frame 1 is transferred to the next mold 12.
The cavity 13 of this mold 12 has finished dimensions, and the tip of the metal frame 1 is inserted into the mold 12 so that the sealing body 4 is located at a predetermined position in the cavity 13 (see Fig. 3). .

Then, the mold 12 is closed and clamped, and the cavity 13 is filled with the same second resin as the primary sealing body 4 at high injection speed and high injection pressure. Wrap it together with the tip.

As a result, the secondary sealing body 5 having the finished dimensions is molded on the primary sealing body 4, and the chip 2 and wire 3 are completely sealed with resin from the tip of the metal frame 1 (see Fig. 4). ).

Note that if heat resistance is required, a heat-resistant material such as glass-containing PBT, PPS, PEI, or PES may be used as the second resin.

FIG. 5 shows an injection molding machine that can carry out the present invention, and the injection molding machine is installed upright on a machine stand 21,
A direct pressure type mold clamping device 22 to which the movable molds of the two sets of molds 11 and 12 can be attached, and a mold clamping device 22 provided in parallel opposite to each of the two sets of fixed molds provided on the machine stand 21. It has two in-line screw type injection devices 23 and 24.

Among the molds 11 and 12, the first injection device 2
The first mold 11 provided corresponding to No. 3 has the cavity 10 smaller than the predetermined size of the LED that partially seals the metal frame insertion part and the metal frame tip with resin, The second mold 12 provided corresponding to the second injection device 24 is
It has a metal frame insertion part that is primarily sealed by a first mold 11, and a cavity 13 that seals the metal frame tip end with resin to a predetermined size.

However, first, the metal frame 11 is inserted into the first mold 11 and the mold is clamped, and then the first injection device 23 injects the gold wire 3 at a low speed and pressure so as not to break it. Filling is performed to form the above-mentioned primary sealing body 4. After the resin has been cooled and solidified, the mold is opened, and the primarily sealed metal frame 1 is taken out from the fixed mold and inserted into the fixed mold of the second mold 12. At the same time, a new metal frame 1 is inserted into the fixed mold, and then the mold is clamped and the first mold 11 is inserted.
Next, mold the primary sealing body 4 in the same manner as above,
In the second mold 12, the primary sealing body 4 at the tip of the metal frame is filled with the secondary sealing body 5 made of resin filled into the cavity 13 at high injection speed and pressure by the second injection device 24. molded. and,
After the resin cools and solidifies, the molds are opened again and the products are taken out from both fixed molds.The products with the secondary sealing body 5 are sent to the next process, and the ones with the primary sealing body 4 are sent to the next fixed mold. be transferred to.

In addition, inserting the metal frame 1 into the above fixed mold,
The transfer of the metal frame 1 from one fixed mold to the next fixed mold and the removal of the metal frame 1 from the fixed mold can be easily automated by a robot.

(Effects of the Invention) According to the present invention, resin encapsulation of LEDs is performed by two steps: forming a primary encapsulation body by low-speed injection and low-pressure injection, and forming a secondary encapsulation body by high-speed injection and high-pressure injection. Therefore, defects such as gold wire breakage, flow marks, and weld lines are less likely to occur.
In addition to greatly improving yield, secondary sealing is fast and
Since it can be carried out under high pressure, the precision of the molded product is improved, LEDs with excellent optical properties can be easily obtained in a short period of time, productivity is also significantly improved, and costs can be reduced.

[Brief explanation of drawings]

The drawings illustrate the method for resin-sealing a light emitting diode according to the present invention, and FIGS. 1 to 4 are explanatory diagrams showing the steps in order, and FIG. 5 is a schematic perspective view of an injection molding machine. 1...Metal frame, 2...LED chip,
3... Wire, 4... Primary sealing body, 5... Secondary sealing body, 10, 13... Cavity, 11, 12
……Mold.

Claims (1)

[Claims] 1. When sealing the light-emitting diode chip die-bonded and wire-bonded to the tip of the metal frame with resin together with the wire, insert the tip of the metal frame into a mold with a cavity smaller than the finished dimension, and insert the die into the cavity. The first resin is filled at low injection speed and pressure to temporarily form a sealing body that encloses the chip and wire together with the tip of the metal frame, and then transfers the metal frame to another mold. A light emitting diode characterized in that the tip part is inserted into a finishing cavity together with the primary sealing body, and a second resin is filled at high injection speed and pressure to form a secondary sealing body. resin sealing method.