JP3131474B2 - Resin molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molding method for molding a resin molded product such as a lead frame.

[0002]

2. Description of the Related Art In a molding apparatus for a resin molded product such as a lead frame, a molded product is positioned and set in a mold, and after the molded product is clamped, a molten resin is placed in a cavity. Fill and mold. The cavity and the pot containing the molten resin are connected by a resin path, and the resin in the pot is pressure-fed by a plunger so that the cavity is filled with the resin and molded. By the way, in semiconductor device products using a lead frame or TAB, products having an extremely thin package have recently been produced. In such a thin package product, there is a problem in that the gap between the cavities is narrow, so that the flowability of the resin is deteriorated and the resin is difficult to mold.

In a resin mold of a lead frame or TAB, since a semiconductor chip is mounted on a frame and filled with resin, a gap in which the resin flows is further narrowed and the resin does not easily flow. Since such a narrow space has a small internal volume, heat exchange proceeds when the resin is filled, and the viscosity becomes higher, so that the flow becomes more difficult. As a result, there is a place in the cavity where the resin does not easily flow, and there is a problem that the resin is not filled in the molded product. In order to improve the flowability of the resin, for example, it is conceivable to use a resin that is low in viscosity and is not easily increased in viscosity by heat exchange. However, this method does not provide a basic solution and lowers productivity. There is a problem that. The present invention has been made to solve these problems, and its purpose is to solve the problems of resin flowability and the like even when molding a resin molded product having a very thin package. A resin molding method that enables resin molding and facilitates resin molding of thin packaged products, and enables easy molding even for products that were extremely thin and could not be molded .
In providing the law .

[0004]

The present invention has the following arrangement to achieve the above object. That is, a molded product such as a lead frame is clamped with a mold and the plunger
In the resin molding method of resin-pressing the resin from the pot to the cavity by means of a mold, the molding metal
Mall mold, the end surface is slidable bottom member in the mold opening and closing direction constituting the inner bottom surface of the cavity, the object to be molded article
And clamp the bottom member with a drive mechanism.
The position of the end face is on the mold surface more than the thickness position of the final package
Move to the retracted position above, and use the drive mechanism
The supporting pressure of the bottom member is increased by the resin by the plunger.
Set the injection pressure relatively lower than the
After filling the cavity and filling the cavity with resin, the drive
The pressing force of the bottom member by the mechanism
The bottom pressure is set relatively higher than the holding pressure
Push the member until the end face position is
After moving, hold the pressure, cure the resin and mold it into a predetermined shape.
Characterized in that that. After the resin is cured,
Bottom member provided on the upper or lower mold of the mold
One end of the cavity from the position of the inner bottom surface of the cavity.
And releasing the molded product .

[0005]

[Function] When injecting resin into the cavity for the first time, the bottom member is retracted more than the package thickness of the molded product, the flow gap of the resin is increased, high flow resistance is relaxed, and controllability of the injection path is secured. At the same time, the volume of the cavity is increased to keep the flow resistance of the resin low, thereby completing the resin injection. After the completion of the resin injection, the bottom member is extruded to the thickness of the package size, and is molded with a predetermined package size. When injecting the resin, the filling capacity of the resin can be improved by increasing the cavity volume, and the resin is molded into a regular package size by compressing with the bottom member. This makes it possible to reliably perform resin molding even for an extremely thin package product.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a resin molding according to the present invention.
1 is a cross-sectional view illustrating a configuration of an embodiment of a resin molding apparatus to which a molding method is applied . In the figure, reference numeral 10 denotes a molded article such as a lead frame, 12 denotes a lower mold, and 14 denotes an upper mold. Reference numeral 16 denotes a cavity for filling with resin, which is provided on the upper and lower surfaces of the molded article 10. Reference numeral 18 denotes a resin path runner that fills the cavity 16 with the molten resin. In the present embodiment, gates 20 are respectively provided on the upper and lower surfaces of the molded article 10 so that the upper and lower cavities 16 are provided.
Are filled with resin. Reference numeral 22 denotes a cull portion that communicates with the runner 18, and reference numeral 24 denotes a plunger that feeds the resin in the pot 26 to the cavity 16.

In the conventional molding die, the molten resin is pressure-fed by a plunger 24 and the cavity is filled with the resin to form the resin. In the molding apparatus according to the present invention, the bottom surface in the cavity of the molding die is movably provided. Thus, the resin flow at the time of filling the resin is facilitated. 2
Reference numerals 8 and 30 denote bottom members provided for making the inner bottom surfaces of the cavities 16 formed in the lower mold 12 and the upper mold 14 movable.
Sliding holes for sliding the upper and lower members 8 and 30 in the mold opening and closing direction are provided, and drive mechanisms such as servomotors 32 and 34 for pushing the bottom members 28 and 30 are installed. Servo motor 32, 3
4 is for pushing the bottom members 28 and 30 with a predetermined accuracy.

Next, a procedure for resin molding using the molding apparatus of the above embodiment will be described. First, the end surfaces of the bottom members 28 and 30 that form the inner wall surface of the cavity are moved to positions where they are pulled inward from the final package thickness position. FIG. 1 shows a state in which the bottom members 28 and 30 are retracted and the bottom members 28 and 30 are filled with resin.
30 is in a retracted state. Bottom members 28, 30
May be set as appropriate, but may be about 0.2 mm. Bottom members 28 and 30 are pulled in by servo motor 3
2 and 34 are driven to stop accurately according to the encoder data.

Next, the molded article 10 is set in a mold, clamped by the lower mold 12 and the upper mold 14, and the plunger 24 is operated to inject resin. Thereby, the resin is injected into the upper and lower cavities 16. The rising of the reaction force against the plunger 24 at the time of the resin injection is detected to control the pressing movement of the plunger 24 to cope with the weight variation of the tablet. When the plunger 24 is stopped based on the encoder as an application example, the bottom member 28,
The support pressure of 30 is set relatively lower than the injection pressure of the resin by the plunger 24, and the resin injection is performed with the bottom side adapted based on the plunger coordinates. Since the resin injection step is performed at a position where the end surfaces of the bottom members 28 and 30 are retracted from the final package thickness position, the void amount of the cavity 16 is increased by that amount, and the resin flow is improved and the resin flow into the cavity 16 is improved. Filling can be performed easily.

Next, the bottom members 28 and 30 are pushed to the regular package thickness position. The bottom members 28 and 30 are accurately stopped based on the encoder data. The servo motors 32 and 34 are rotated in reverse from the retracted position, and the bottom members 28 and 30 are synchronously moved in the facing direction. In this step, the pressing force of the bottom members 28 and 30 is set to be relatively larger than the holding pressure of the plunger 24, and the resin is pushed back from the cavity 16 to the cull 22 side. The plunger 24 is thereby slightly pushed back.

When the end surfaces of the bottom members 28 and 30 reach the regular package thickness positions, the process proceeds to the pressure holding step. The resin is compressed and hardens. After the curing time has elapsed, open the mold about 0.3 mm. Bottom member 2 of upper mold or lower mold to release molded product from one of upper mold or lower mold
Extrude 8, 30 about 0.2mm. Open the mold and release the molded product from the other mold. In the same manner as described above, the bottom member is extruded to release the molded product from the mold.
After the mold is cleaned, the process proceeds to the next molding operation. Thus, resin molding is continuously performed.

As described above, in the resin molding apparatus according to the present embodiment, the resin is filled in a cavity having a thickness larger than the package size, and then the product is compressed and molded to the thickness of the product package. It is possible to easily perform resin molding even with a product having the same.
Further, since the resin is filled in a cavity state that is thicker than the package size, the filling property of the resin is improved, and problems such as unfilled resin and deformation due to resin pressure during resin injection can be solved. This enables stable mass production of ultra-thin packaged products conventionally considered impossible to mold.
Further, the characteristics of the usable resin are widened, and the allowable width of the resin can be widened. In addition, when the package thickness is reduced, the package strength is inevitably reduced, and there is a problem that the package is damaged by the ejecting operation using the ejector pins as in the related art. Therefore, it is possible to solve the problem when the molded product is released from the mold. Also, the bottom member 28,
By appropriately setting the timing of extruding the molded product by 30, the release position of the molded product can be specified, and handling of the molded product can be facilitated.

Although FIG. 1 shows a state in which one cavity is filled with resin, it is needless to say that a plurality of cavities can be similarly configured. In addition, the type and cavity shape of the molded product, the shape of the resin path,
The present invention can be applied to various types of apparatuses regarding the arrangement of pots, the method of filling the resin, and the like. Further, in the embodiment, the end surface of the bottom member corresponds to almost the entire bottom surface of the cavity, but may be set to a part of the inner bottom surface of the cavity. However, considering the releasability of the molded product, the end area of the bottom member is preferably set to a somewhat large area.

[0014]

According to the resin molding method of the present invention, as described above, a resin molded product having an extremely thin package can be easily and reliably molded, and a non-defective product having no resin filling or the like. Can be manufactured stably, and it was extremely impossible in the past.
This makes it possible to perform a resin molding of a product having a small package thickness .

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a resin molding method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Molded product 12 Lower mold 14 Upper mold 16 Cavity 18 Runner 20 Gate 22 Cull part 24 Plunger 26 Pot 28, 30 Bottom member 32, 34 Servo motor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification symbol FI H01L 21/56 H01L 21/56 T // B29K 105: 20 B29L 31:34 (58) Fields surveyed (Int.Cl. ⁷ , (DB name) B29C 45/00-45/84 B29C 33/00-33/76

Claims (2)

(57) [Claims] An object to be molded such as a lead frame is clamped by a mold, and a plunger is used to remove the molded product from the pot.
Resin mold to send resin to Viti by resin molding
In the method, the molding die, slidable bottom member end surface constitutes the inner bottom surface of the cavity in the mold opening and closing direction, clamping the object to be molded article mold, the drive mechanism
The position of the end face of the bottom member is more than the thickness of the final package.
From the retracted position to the retracted position on the mold surface.
The supporting pressure of the bottom member by the drive mechanism
Relatively lower than resin injection pressure by plunger
After setting, filling the cavity with resin, filling the cavity with resin,
The pressing force of the bottom member is maintained by the plunger.
Relative to the end surface
A resin molding method characterized in that after a position is pushed to a regular thickness position of a package, a pressure is maintained, the resin is cured and molded into a predetermined shape . 2. After the resin has hardened, the molding die
Attach one of the bottom members provided on the upper mold or lower mold
Extrude the end face from the position of the inner bottom
2. The resin molding method according to claim 1, wherein the mold is released.