JP4195704B2 - Resin molding method - Google Patents

Description

  The present invention relates to a resin molding method in which reliability and optical properties are improved by preventing gas residue in a resin molding, particularly transfer resin molding.

  Conventionally, when a lead frame for an LED or the like having an uneven structure is resin-molded, a transfer molding apparatus is mainly used.

  FIG. 3 shows such a pot type transfer molding apparatus, wherein 1 is an upper mold, 2 is a lower mold, 3 is a pot formed on the upper part of the upper mold 1, 4 is a plunger press-fitted into the pot 3, 5 Is a hot platen, and a lead frame provided with an object to be sealed, such as an LED, is inserted between the upper mold 1 and the lower mold 2 and a preheated sealing material 6 such as a thermosetting resin is placed in the pot 3. The plunger 4 is press-fitted into the pot 3 and a thermosetting resin is press-fitted between the upper mold 1 and the lower mold 2 to be cured.

  However, if the resin is molded into a cup shape with a lens or reflector structure inside by a conventional molding method, especially the transfer molding method, it is not possible to completely prevent residual gas in the lens and cup after molding. There wasn't.

  Although evacuation was also considered as a method to prevent gas residue, partial evacuation is not effective because the structure of the mold becomes complicated and the evacuation state cannot be maintained during resin molding. It was. In order to increase the effect, the method of keeping the entire mold in a vacuum is impractical because the equipment must be large and the productivity is lowered. For these reasons, a method of removing the gas remaining in the resin by a method of evacuating the resin filling portion of the resin mold and the entire mold is not actually employed.

  In addition, when a thermosetting resin is used, it is necessary to discharge air before the resin is filled and cured, and this is achieved by controlling the curing time, the filling speed, and the pressure of the cavity in each mold in a well-balanced manner. It is necessary.

  This balance condition is very delicate. Especially in resin molded products with a lens structure and resin molded products with a structure that has a cup-shaped reflecting mirror in the lead frame for the purpose of optical condensing, the lens section and cup It was inevitable that gas remained in the part.

  If gas remains in the resin molded product, the optical radiation pattern and light receiving pattern will be greatly deformed, and the required light output and light receiving capacity will be attenuated. The separation is promoted and the performance is further deteriorated.

  The object of the present invention is to eliminate the above-mentioned problems.

  The present inventor has intensively studied to solve such problems, and it is possible to reduce the residual gas by replacing the air around the sealing material and the air remaining in the mold with a specific gas in advance. For example, it has been found that a gas that sublimates by compression, a gas that dissolves in a resin, a gas that has a small molecular structure and easily escapes, and a gas that has a refractive index close to that of a resin are preferable. The present invention has been made based on such findings.

The resin molding method of the present invention includes a step of placing an object to be sealed in a mold formed between an upper mold and a lower mold, and a resin before curing in a pot formed in the upper mold. Introducing the air replacement gas into the pot and the mold in a state where the upper mold and the lower mold are separated from each other through a replacement gas introduction nozzle provided to be freely moved back and forth in a plunger inserted into the pot. And the step of pushing the resin into the mold by inserting the plunger into the pot while continuing to introduce the air replacement gas in a state where the upper mold and the lower mold are joined to each other. Features.

In the resin molding method of the present invention, the step of introducing the air displacement gas into the pot and the mold is made through the replacement gas introducing nozzle tip opening which is inserted into the pot from the plunger Rukoto It is characterized by.

  The object to be sealed is an LED, and the LED is provided on a lead frame.

  The air replacement gas is a gas having a refractive index close to that of the resin.

  The air replacement gas is a gas that dissolves in the resin by being compressed.

  The air replacement gas is one or more selected from an inert gas such as carbon dioxide, argon gas, nitrogen gas and helium gas, or an organic gas such as methane, ethane, butane and ethylene. To do.

  As described above, according to the present invention, it is possible to obtain a great effect capable of preventing gas residue. In addition, the method of the present invention can be carried out with only a slight change in the work flow without affecting the productivity, and a great effect including improvement in reliability and improvement in yield can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings.

  In the present invention, as shown in FIG. 1, a hole 7 extending in the axial direction is formed in the plunger 4, and a gas ejection nozzle 8 with the bottom surface of the tip closed is inserted into the hole 7. An opening 9 that opens to the side is provided so that pressurized gas can be ejected from the opening 9 through the nozzle 8 and the hole 7 of the plunger 4.

  Further, a flange portion 10 is formed on the upper portion of the nozzle 8, and an extension spring 11 is inserted between the lower surface of the flange portion 10 and the inner wall of the plunger 4, and the extension spring 11 is relative to the plunger 4. The nozzle 8 is restrained upward, and the tip of the nozzle 8 is always drawn into the hole 7 of the plunger 4, but pressurized gas is introduced into the hole 7 from the upper end of the hole 7 of the plunger 4. Then, the pressure of the pressurized gas acts on the upper surface of the flange portion 10 of the nozzle 8, and the nozzle 8 is pushed downward relative to the plunger 4 against the extension spring 11, The opening 9 is projected from the lower surface of the plunger 4 as shown in FIG.

  In the method for producing a resin molded product of the present invention, a sealed object (not shown) such as a lead frame to which an LED or the like is attached is inserted between the upper mold 1 and the lower mold 2 and preheated in the pot 3. The stopper material 6 is put in, the plunger 4 is lowered and the bottom surface of the pot 3 is closed, and the upper die 1 and the lower die 2 are separated from each other by about 5 mm. In this state, the pressure is applied in the hole 7 of the plunger 4. Gas is continuously introduced.

  As a result, the tip of the nozzle 8 in the hole 7 of the plunger 4 protrudes out of the plunger 4 and enters the pot 3, and the pressurized gas passes around the sealing material 6 in the pot 3 from the opening 9 of the nozzle 8. The air enters the upper mold 1 and the lower mold 2 from above, and the air around the sealing material 6 is continuously replaced by the gas (gas filling 1).

  Next, the upper die 1 and the lower die 2 are joined to each other, and the introduction of the pressurized gas is continued to maintain the state as it is (gas filling 2).

  Next, the plunger 4 is further lowered, the sealing material 6 is pressed, and extrusion molding is performed in the upper mold 1 and the lower mold 2.

  In the present invention, one or more selected from an inert gas such as carbon dioxide, argon gas, nitrogen gas and helium gas, or an organic gas such as methane, ethane, butane and ethylene is used as the gas. .

  Table 7 shows the results of visual inspection using a 20-fold stereo microscope for the remaining number and content of gas in a resin molded product obtained by the method of the present invention using carbon dioxide as a gas and 80 shots per shot. It is shown in 1.

  As is apparent from Table 1, the number of products in which the gas remained in all the products molded in the mold by one molding was lower than that in which no gas was introduced, In the gas filling 1 and filling 2 operations, the number of products in which the gas remains is lower.

  The reason for this is that no gas was formed inside, or even if it was formed, this was a gas other than air, and this gas changed to a material close to the optical refractive index of the resin, and the gas became invisible. A liquid bubble was formed in place of the gas, but the size of the liquid bubble was reduced to make it invisible.

It is sectional drawing of the principal part of the apparatus for enforcing the resin molding method of this invention. It is sectional drawing of the principal part of the resin molding apparatus shown in FIG. It is explanatory drawing of the conventional resin molding apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper mold | type 2 Lower mold | type 3 Pot 4 Plunger 5 Heating board 6 Sealing material 7 Hole 8 Nozzle 9 Opening 10 Flange part 11 Extension spring

Claims (6)

Placing a sealed object sealed by a resin in a mold formed between an upper mold and a lower mold;
Putting the resin before curing in the pot formed in the upper mold ,
Introducing the air replacement gas into the pot and the mold in a state in which the upper mold and the lower mold are separated from each other via a replacement gas introduction nozzle provided in a plunger inserted into the pot ;
Resin, characterized by comprising more and extruding the resin into the mold by the plunger while continuing the introduction of air displacement gas in a state joined together the upper and lower molds are inserted into the pot Molding method. Process, a resin molding according to claim 1, wherein Rukoto made via a replacement gas introducing nozzle tip opening which is inserted into the pot from the plunger for introducing the air displacement gas into the pot and the mold Method. The Hifutomebutsu is LED, and claim 1 or 2 The method of resin molding, wherein the LED is characterized that you have provided on the lead frame. The air replacement gas, according to claim 1, 2 or 3 resin molding method wherein gas der Rukoto close to that of the resin and the refractive index. The air replacement gas, according to claim 1, 2, 3 or 4 The method of resin molding, wherein a gas der Rukoto dissolved in the resin by compressing. Wherein the air displacement gas, carbon dioxide gas, argon gas, nitrogen gas, inert gas such as helium gas, methane, ethane, one or one or more der Rukoto selected from organic gases butane, ethylene, etc. The resin molding method according to claim 1, 2, 3, 4 or 5.

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