JP3335792B2 - Electronic component resin molding method and resin molding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding electronic parts such as ICs and diodes and a molding apparatus therefor, including a step of molding a resin mold portion in a cavity formed on a mating surface of an upper and lower mold. More particularly, the present invention relates to a resin molding method and a resin molding apparatus for an electronic component characterized by the shape of a communication path for releasing air in a cavity to the outside of a mold.

[0002]

2. Description of the Related Art In general, molding of a resin molded portion of an electronic component such as an IC using a metallic lead frame of iron or the like is performed as follows. 6 and 7, a resin pot 33 for accommodating a resin tablet 32 made of epoxy resin or the like, and a runner groove 34 connected to the resin pot 33 and extending along the longitudinal direction of the lead frame 31.
A lower mold 37 engraved on a mating surface with a resin mold part forming cavity 36 communicating with a plurality of gate grooves 35 branching from the runner groove 34 and a cavity 38 at a position corresponding to the cavity 36 (FIG. (Not shown) is sandwiched between the upper mold 39 and the strip-shaped lead frame 31 from above and below, and the resin melted in the resin pot 33 is heated and melted from the runner groove 34 by raising a plunger (not shown). By guiding the semiconductor chips (not shown) mounted at regular intervals along the longitudinal direction of the lead frame 31 by guiding them into the cavities 36 and 38 via the gate grooves 35, The resin mold part 40 of the component is molded.

[0003] On the mating surface of the lower mold 37, a communication passage 41 for bleeding air in the cavities 36, 38 is cut from the cavities 36, 38 toward the side surface of the lower mold 37. A rectangular parallelepiped groove 42 is formed in the communication passage 41 near the cavity 36. Accordingly, the molten resin is filled while removing the air in the cavities 36 and 38 into the communication passage 41, and also enters the communication passage 41 with the removal of the air, and the excess resin flows into the groove 42. Is stored. As a result, some of the molten resin
The lead frame 31 is integrally formed with the resin mold portion 40.
The resin adheres to the lower surface and is molded as the unnecessary resin 43 (see the hatched portion in FIG. 7). It should be noted that a substantially rectangular through-hole 31 a formed in the lead frame 31 is located on the groove 42. For this reason, as shown in FIG. 8A, the unnecessary resin 43 is attached to the periphery of the through hole 31a on the lower surface of the lead frame 31 (the attached portion is indicated by oblique lines).

After the lead frame 31 is released from the upper and lower dies 37 and 39, it is transferred to the next step by a transfer means such as a suction collet. In this next step, the lead frame 31 (not shown here) is placed on a fixed base while being held by holding means, and in this state, a substantially cylindrical protruding pin is used to move the projecting pin such as a cylinder. The through-hole 31a of the lead frame 31 is driven by driving.
, And presses the unnecessary resin 43 formed below the through-hole 31a, whereby the unnecessary resin 43 is separated and removed from the lower surface of the lead frame 31.

Further, in the next step, the unnecessary resin 43b formed in a state of being adhered to the lower surface of the lead frame 31 is immersed in a solution such as pyrrolidone through the communication path 41 between the resin mold portion 40 and the unnecessary resin 43. By being melted, it is separated and removed from the lead frame 31.

[0006]

However, the above conventional resin molding method has the following problems. When the unnecessary resin 43 is pressed by a protrusion pin (not shown), a peeling force is applied to a portion adhered to the lower surface of the lead frame 31.
In the portion attached to the lower surface, the force of peeling from the lead frame 31 decreases as the distance dimension from the peripheral edge of the through hole 31a increases, so that the corner 43a having the largest distance dimension from the peripheral edge of the through hole 31a The force for peeling is smaller than that of the other adhesion parts. Therefore, a part of the unnecessary resin 43 is, as shown in FIG.
In some cases, the corners 43a may not be completely removed from the lower surface of the lead frame 31 and may remain as resin burrs while being attached to the lead frame 31.

The unnecessary resin 43 remaining and adhered in such a state cannot be completely dissolved by the above-mentioned solution because of its large thickness. Accordingly, the lead frame 31 is transferred to a step of performing punching or lead bending such as lead cutting in a state where the unnecessary resin 43 remains. For example, when the lead frame 31 is disposed between upper and lower molds used for these processing, In some cases, the positioning accuracy may be insufficient due to the unnecessary resin 43 getting on the mounting surface of the mold, and in this case, there is a problem that lead punching failure, bending failure, or the like is caused.

The present invention was conceived under the above circumstances, and provides a method and apparatus for molding an electronic component capable of reliably removing a predetermined portion of unnecessary resin adhering to a lead frame. Aim.

[0009]

According to the present invention, a lead frame having a through hole is sandwiched between upper and lower dies and melted in a cavity formed on a mating surface of the upper and lower dies. While filling the resin, the air in the cavity is communicated with the outside of the upper and lower molds and discharged to the outside of the upper and lower molds through a communication passage having a chamfer-shaped groove near the cavity. A resin molding method for an electronic component, wherein a resin molded portion is molded so as to cover a semiconductor chip on a frame, wherein the lead frame is sandwiched by the upper and lower molds at positions where the through holes correspond to the grooves of the communication passage. The present invention provides a resin molding method for an electronic component, wherein molten resin leaking into the communication path in this state is stored in the groove.

The present invention further provides a cavity formed on a mating surface of the upper and lower molds for molding a resin mold portion covering the semiconductor chip on the lead frame, and a cavity formed on at least one mating surface of the upper and lower molds. And a communication path for communicating the cavity with the outside of the upper and lower molds, and a resin molding apparatus for an electronic component, wherein the communication path is
A resin molding device for an electronic component, comprising a groove near the cavity, wherein a corner of the groove is chamfered.

Further, the present invention provides a resin molding apparatus for electronic parts, wherein the corner of the groove is chamfered in an R shape in the above resin molding apparatus.

[0012]

According to the present invention, the molten resin discharged from the cavity into the communication passage together with the air in the cavity is located below the through hole of the lead frame and has a chamfered corner. Because it is stored in the groove,
Unnecessary resin is formed in a state where the corners are chamfered so as to follow the shape of the groove. For this reason, even if the unnecessary resin in the groove portion is formed in a state where the unnecessary resin adheres to the periphery of the through hole and / or in the through hole on the lead frame surface, the unnecessary resin is removed at a portion where the unnecessary resin adheres to the lead frame surface. The molding can be performed so that the width dimension between the outer edge and the peripheral edge of the through hole becomes substantially uniform.

That is, when, for example, the unnecessary resin is pressed against the above-mentioned through-hole by a pin which can move up and down, a peeling force is applied almost uniformly to all the portions adhering to the lead frame surface. Therefore, it is possible to reduce the corner portions remaining as resin burrs. Therefore, according to the present invention, it is possible to reduce the adhesion of the unnecessary resin molded in the groove to the lead frame, so that the mounting and transfer of the lead frame in the next process of the resin molding process can be reduced. It can be done smoothly.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 5 taking an IC as an example of an electronic component, but the present invention is not limited to this. FIG.
It is a perspective view which shows the principal part of the apparatus which shape | molds the resin mold part of IC. FIG. 2 is a cross-sectional view of a main part showing a state in which a lead frame is sandwiched between upper dies in the above device.

In this apparatus, a resin mold portion for covering semiconductor chips (not shown) mounted at regular intervals in a longitudinal direction on a strip-shaped lead frame 1 is formed. A lower mold 2 and an upper mold 3 made of a cemented carbide sandwiched between the lower mold 2 and the upper mold 3. The lower mold 2 is fixed on a base (not shown).
A resin pot 5 for accommodating a columnar resin tablet 4 made of epoxy resin as a mold resin material is provided on a mating surface with the upper mold 3, and is connected to the resin pot 5 and extends along the longitudinal direction of the lead frame 1. A runner groove 6; a plurality of gate grooves 7 branching from the runner groove 6;
A cavity 8 for molding the resin mold portion, which communicates with the outside of the mold, and a communication passage 9 having a concave shape in a cross-sectional view (a cross-section as viewed from the arrow A in FIG. 1) are respectively formed from the cavity 8 to the outside of the mold.

As shown in FIG. 3, a substantially rectangular parallelepiped groove 10 is formed in the communication passage 9 in the vicinity of the cavity 8 thereof. The four corners 10a of the groove 10 are rounded. As shown in FIG. 2 (FIG. 2 is a cross-sectional view of a main part in a state where the upper and lower dies 2 and 3 are clamped), the upper die 3 is moved downward by expansion and contraction of a hydraulic cylinder (not shown). It moves up and down with respect to the mold 2, and a cavity 12 facing the cavity 8 and a circular concave portion 11 facing the resin pot 5 are provided on the mating surface with the lower mold 2.
And are engraved.

Using the device having such a configuration, the resin mold portion of the IC is formed as follows (FIGS. 1 and 2).
reference). First, in a state where the lead frame 1 is sucked and held by a suction collet (not shown), the opened lower mold 2 is opened.
And between the upper mold 3. Next, each semiconductor chip (not shown), on which the lead frame 1 is mounted on this island, is located on the cavity 8 and a substantially rectangular through hole 1a formed in the lead frame 1 is provided in the lower mold. It is placed so as to be located on the second groove 10. Then, the lead frame 1 is sandwiched between the upper mold 3 and the lower mold 2 by the downward movement of the upper mold 3 toward the lower mold 2 by extension of a hydraulic cylinder (not shown). At this time, each semiconductor chip on the lead frame 1 is in a state surrounded by the cavities 8 and 12 (hereinafter, a space surrounded by the cavities 8 and 12 is referred to as a cavity 13). Thereafter, the resin tablet 4 previously housed in the resin pot 5 by the conventional suction conveyance method is moved to a heater (not shown) provided inside the lower mold 2.
And the molten resin is pressed by the rise of a plunger (not shown) fitted into the resin pot 5 to be inserted into the cavity 13 through the runner groove 6 and the gate groove 7 so that the lead frame 1 is melted. Fill so as to cover the upper semiconductor chip.

At this time, in the cavity 13,
The molten resin is filled so as to push the air into the communication passage 9, a part of which enters the communication passage 9 so as to be drawn into the air, and is stored in the groove 10 provided in the communication passage 9. The molten resin stored in the groove 10 is shown in FIG.
(FIG. 4 is a bottom view of the main part of the lead frame 1), the corner 14a of the groove 10 is attached to the inside of the through hole 1a on the lower surface of the lead frame 1 and around the periphery thereof. The unnecessary resin 14 is molded so as to have an R-chamfered shape following the shape of the 10a.

The unnecessary resin 14 is formed so that the width from the outer edge to the peripheral edge of the through hole 1a is substantially uniform at the portion where the unnecessary resin 14 adheres to the surface of the lead frame 1 (the hatched portion in FIG. 4). In the cavity 13, a resin mold portion 15 is formed simultaneously with the molding of the unnecessary resin 14 so as to be connected to the unnecessary resin 14. In this state, the lead frame 1 is released from the upper and lower dies 2, 3 and transferred to the next step by a conventional suction transfer method (not shown).

In the next step, as shown in FIG. 5, a fixed base 16 is provided, and the lead frame 1 is mounted on the base 16. Then, by lowering the protruding pin 17 made of substantially cylindrical aluminum which can be moved up and down by cylinder driving with respect to the base 16,
The unnecessary resin 14 on the lead frame 1 is pressed. At this time, the unnecessary resin 14 is uniformly applied with a peeling force to all the portions adhering to the surface of the lead frame 1, so that the corners 14a are less likely to remain as resin burrs. It is possible to do.

Therefore, according to the present invention, it is possible to reduce the residual adhesion of the unnecessary resin 14 to the lead frame 1. Regarding the groove 10 in the present invention, the corner 10
The chamfered shape of a may be a C-chamfered shape, and is not limited thereto. Further, in the present embodiment, the communication path connecting from the cavity is engraved only in the lower mold, but is not limited thereto.
The effects of the present invention can be obtained by providing the upper mold alone or both the upper and lower molds.

Further, the position where the groove 10 is provided is preferably a position near the cavity, but the distance from the cavity 14 is not limited thereto. In addition, in the present embodiment, the upper die is movable, but the present invention is also applicable to a movable lower die or both upper and lower movable die. When the communication path is provided only in the upper mold, the unnecessary resin formed in the groove can be easily removed.

[Brief description of the drawings]

FIG. 1 is a perspective view of an essential part showing an apparatus for molding a resin mold part of an IC in this embodiment.

FIG. 2 is a sectional view of a main part showing an apparatus for molding a resin mold part of an IC in the present embodiment.

FIG. 3 is an enlarged perspective view of a main part showing a groove formed in a communication passage in the embodiment.

FIG. 4 is a main part bottom view showing a lead frame in which unnecessary resin is molded in the present embodiment.

FIG. 5 is an explanatory diagram illustrating a state in which unnecessary resin is separated from a lead frame in the present embodiment.

FIG. 6 is an explanatory diagram for explaining a method of forming a resin mold portion of a conventional IC.

FIG. 7 is an explanatory diagram for explaining a method of molding a resin mold portion of a conventional IC.

FIG. 8 is an explanatory view for explaining a state in which an unnecessary resin is partially adhered and remains on a lead frame in a conventional method of molding a resin mold portion of an IC.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lead frame 2 Lower die 3 Upper die 4 Resin tablet 5 Resin pot 6 Runner groove 7 Gate groove 8 Cavity 9 Communication passage 10 Depression 11 Through hole 12 Extrusion pin 13 Cavity 14 Depression 15 Through hole 16 Extrusion pin 17 Cab Tee 18 Unnecessary resin

Claims (3)

(57) [Claims] 1. A lead frame having a through hole is sandwiched between upper and lower molds, and while filling a cavity formed in a mating surface of the upper and lower molds with a molten resin, air in the cavity is moved up and down. The resin is discharged to the outside of the upper and lower dies through a communication passage communicating with the outside of the mold and having a chamfered groove near the cavity, and a resin mold portion is formed so as to cover the semiconductor chip on the lead frame. A resin molding method for an electronic component, wherein the lead frame is sandwiched by the upper and lower molds at positions where the through holes thereof correspond to the grooves of the communication path, and in this state, the molten resin leaking into the communication path, A resin molding method for an electronic component, wherein the resin molding is accommodated in a groove. 2. A cavity engraved on a mating surface of the upper and lower dies and molding a resin mold portion covering the semiconductor chip on the lead frame, and a cavity engraved on at least one mating surface of the upper and lower dies. And a communication path for communicating the outside of the upper and lower molds with the outside of the upper and lower molds, wherein the communication path has a groove near the cavity, and a corner of the groove is chamfered. A resin molding apparatus for electronic components, characterized in that: 3. The resin molding apparatus for an electronic component according to claim 2, wherein a corner of the groove is chamfered into an R shape.