Plastic article or earthenware shaping or treating: apparatus – Control means responsive to or actuated by means sensing or... – Article ejector or stripper control
Reexamination Certificate
2000-05-30
2002-08-20
Heitbrink, Tim (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Control means responsive to or actuated by means sensing or...
Article ejector or stripper control
C264S334000, C425S444000, C425S556000
Reexamination Certificate
active
06435855
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resin-molding mold unit and a resin-molding apparatus provided with the resin-molding mold unit, and more particularly to the resin-molding mold unit and the molding apparatus both adapted to seal a semiconductor chip or like elements by molding of a resin.
2. Description of the Related Art
In a mass-consumption society of modern times, various types of products are mass-produced and mass-consumed. Consequently, an art of molding a resin is one of essential arts for supporting the mass-consumption society. A method for molding the resin has a wide variation. In a brief summary, the method is carried out by injection or potting of a molten resin in a mold. In this case, when an element such as a semiconductor chip or a like is previously disposed in the mold, it is possible to seal the element as a whole or to seal a part of the element by injection or potting of the resin (hereinafter referred to as a molding operation). In this molding operation, after completion of molding the resin, it is often difficult to take a molded product out of the mold. In order to avoid the above difficulty, a parting (demolding) agent is often used, which makes it possible to easily take the molded product out of the mold. Further, a suitable ejection means such as an ejection pin or a like is also used in the mold to serve as a mechanism for forcibly taking the molded product out of the mold after completion of molding the resin.
As shown in
FIG. 7A
, there is a conventional type of an ejection pin
103
in the art. The ejection pin
103
is movably mounted in a pin hole formed in the mold. In the molding operation, the ejection pin
103
has its front end portion slightly projected into a cavity of the mold by a length of from approximately 0.05 mm to approximately 0.20 mm. When the molded product is taken out of the mold, the ejection pin
103
is pushed into the cavity of the mold to have its front end portion largely extend into the cavity, so that the molded product is forcibly ejected from the mold. In general, as is clear from
FIG. 7A
, the conventional ejection pin
103
assumes a simple cylindrical shape with a full-diameter flat top surface.
As shown in
FIG. 7B
, there is another conventional type of an ejection pin
113
in the art, for example, as shown in Japanese Patent Application Laid-Open No. Hei 6-243641, wherein, as is clear from
FIG. 7B
, the other conventional ejection pin
113
has its front end portion formed into a circular truncated cone shape, a bottom diameter of which is smaller than an outer diameter of an intermediate portion of the ejection pin
113
to form a shoulder portion therebetween. In general, the ejection pin
113
is projected into the cavity of the mold by a length slightly longer than the above-mentioned ordinary length of from approximately 0.05 to approximately 0.20 mm applied to the front end portion of the previous ejection pin
103
.
Ejection mechanisms such as one for taking the molded product out of the mold using the ejection pin provided in the mold are used not only in the art of resin-molding, but also in arts of metal forging, pressing, and like forming processes. These arts are described in, for example, Japanese Patent Application Laid-Open No. Hei 8-66737 and a like.
However, in a conventional resin-molding apparatus provided with the conventional ejection pins
103
or
113
, the ejection pin has its front end portion extended into the cavity of the mold. This affects the molten resin in flow in the molding operation performed in the mold, and produces a void in the molded product. The thus produced void in the molded product impairs the product in appearance and sealing properties.
More specifically, as shown in
FIG. 8A
, in the case of the cylindrical ejection pin
103
provided with the full-diameter flat top surface, a molten resin indicated by a curved arrow “s” joins at an opposite side of the ejection pin
103
, and, therefore often forms an air trap “v” in a downstream side of the conventional ejection pin
103
. Since the conventional ejection pin
103
has its top surface be smooth and parallel to an inner wall surface of the cavity of the mold, as shown in
FIG. 8B
, there is no possibility that the air trap “v” is removed by a molten resin “t” flowing over the top surface of the conventional ejection pin
103
. As a result, the air trap “v” formed in the molten resin produces the above-mentioned void in the product thus molded.
As for the another conventional ejection pin
113
(shown in
FIG. 7B
) having its front end portion formed into the circular truncated cone shape with a reduced-diameter flat top surface, as is clear from
FIGS. 9A and 9B
, the air trap “v” is also formed in the downstream side of this conventional ejection pin
113
, as is in the case of the previous conventional ejection pin
103
. In this connection, since the conventional ejection pin
113
has its front end portion formed into the truncated cone shape smaller in volume than the corresponding front end portion of the previous conventional ejection pin
103
, it is expected that the air trap “v” formed in the downstream side of this conventional ejection pin
113
is much smaller in volume than the corresponding air trap “v” formed in the downstream side of the previous conventional ejection pin
103
. However, in the molding operation, the truncated cone-shaped front end portion of this conventional ejection pin
113
also serves as a part of the mold, and is therefore extended into the cavity of the mold by a length much longer than that of the corresponding front end portion of the previous conventional ejection pin
103
. Consequently, an actual difference in volume between the air trap “v” formed by this conventional ejection pin
113
and the corresponding air trap “v” formed by the previous conventional ejection pin
103
is substantially negligible.
SUMMARY OF THE INVENTION
In view of the above, it is an object of the present invention to provide a resin-molding mold unit and a resin-molding apparatus provided with the mold unit, and more particularly to provide the mold unit and the molding apparatus both adapted to seal a semiconductor chip or like elements by molding of a resin, and thereby producing a molded product excellent in appearance and sealing properties.
According to a first aspect of the present invention, there is provided a resin-molding mold unit including:
a resin-molding mold member provided with a cavity assuming a predetermined shape, wherein said cavity is defined by an inner wall surface of said resin-molding mold member, and said inner wall surface is provided with a hole; and
a movable member which is movably mounted in said hole of said resin-molding mold member and has its front end portion formed into a semispheric shape.
In the foregoing, a preferable mode is one wherein said resin-molding mold member is further provided with an injection passage through which a molten resin is injected into said cavity of said resin-molding mold member.
Also, a preferable mode is one wherein said resin-molding mold member is integrally provided with a position control mechanism for controlling in position said movable member in a manner such that said movable member has an outer peripheral edge portion of its semispheric front end portion aligned in level with said inner wall surface which defines said cavity of said resin-molding mold member.
According to a second aspect of the present invention, there is provided a resin-molding apparatus for molding a molten resin into a predetermined shape, including:
a resin-molding mold unit comprising a first resin-molding mold member and a movable member, wherein said first resin-molding mold member is provided with a first cavity assuming a predetermined shape, wherein said first cavity is defined by an inner wall surface of said first resin-molding mold member, and said inner wall surface is provided with a hole, wherein said movable member is movably mounted in said hole of said first resi
Heitbrink Tim
Hutchins, Wheeler & Dittmar
NEC Corporation
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