Plastic article or earthenware shaping or treating: apparatus – Distinct means to feed – support or manipulate preform stock... – Opposed registering coacting female molds
Reexamination Certificate
2000-09-27
2003-05-13
Silbaugh, Jan H. (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Distinct means to feed, support or manipulate preform stock...
Opposed registering coacting female molds
C264S272170, C425S129100, C425S573000
Reexamination Certificate
active
06561782
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a molding device and a molding method. More particularly, it relates to a molding device and a molding method for producing an optical semiconductor device, e.g., one used for an IrDA (Infrared Data Association) module.
BACKGROUND OF THE INVENTION
Optical semiconductor devices for transmitting or receiving infrared rays have been used for digital assistant and notebook-sized personal computer-equipped IrDA modules which are used to carry out radio (infrared rays) data communication. Such optical semiconductor devices include lens parts, and are molded with mold resins and then packaged to be used. To mold these optical semiconductor devices, molding devices which are capable of obtaining molded articles with high dimension accuracy have been used. These molding devices are used to mold articles by injecting mold resins from gates into cavities formed by the molds. Since the gates of the molding devices control flow rates of mold resins flowing into the cavities and the filling status within the cavities, whether or not molding articles are successful depends to a large degree on the shape of the gates and their positions.
Particularly, if the shape and the position of the gate of the molding device is not appropriate for the respective cavity, bubbles or voids may be caused in the mold resin when the mold resin is injected. Should such bubbles or voids remain in the finished package, especially in a lens part, optical characteristics for transmitting and receiving infrared rays emitted from an optical semiconductor device may be adversely affected. Further, the occurrence of a weld line (junction line) may cause cracks in addition to being undesirable to the appearance of the final product. Various arrangements of the gate have been considered to remove this defect.
For example, FIGS.
12
(
a
) and
12
(
b
) show examples of a gate
102
that is provided on only one side of a cavity member
100
. In such cases, a mold resin sequentially flows within member
100
without admitting air in the mold resin so that the cavity
100
can be filled with mold resin, which leads to an article free from defects. Consequently, in either case, few failures occur on a hemispherical portion
104
which is closer to the gate
102
because of the pre-injection of the mold resin into the hemispherical portion
104
which is closer to the gate
102
. There has been a problem, however, that a void (voids)
108
may be formed on a hemispherical portion
106
which is further from the gate
102
due to air admitted in the mold resin caused by the flow of the mold resin.
Further, FIGS.
13
(
a
) and
13
(
b
) show examples of gates
112
that are provided on both sides of a cavity member
100
. The gates
112
are respectively arranged adjacent a pair of hemispherical portions
110
. Accordingly, simultaneous injection of the mold resins into the hemispherical portions
110
can produce failure caused by voids which may occur on the hemispherical portions
110
. One problem that may occur, however, when using this approach is that a weld line
114
may be formed between the pair of hemispherical portions
110
where the mold resin merged. Such a weld line might cause further cracks in addition to being undesirable in appearance.
Next, as shown in FIGS.
14
(
a
) through
14
(
c
), there is a method that a plate-like gate
116
is disposed on a cavity member
100
. For example, as the shape of a longitudinal cross section of the plate-like gate
116
is shown in FIG.
14
(
b
), an inclination is provided on the upper surface side of the gate
116
to allow the injected mold resin (not shown) to be directed accurately to the receiving hemispherical portions
110
. In this case, no failures, voids, etc. occurred on the hemispherical portions
110
. However, a large void (or voids)
120
may form on a portion where the mold resin introduced from the lower side of an optical semiconductor element
118
disposed within the cavity member
100
is reversed, or form on a portion where the mold resin introduced from the lower side of the semiconductor element
118
engages the mold resin injected from the upper side of the semiconductor element
118
.
Using the longitudinal cross section of the gate shown in FIG.
14
(
c
) for injecting the mold resin directly into the cavity
100
from the plate-like gate
116
without the shown inclined inner surfaces may result in the formation of voids
122
on the upper part of the hemispherical portions
110
or on the optical semiconductor element
118
. No weld lines as occurred between the hemispherical portions
110
in FIGS.
13
(
a
) and
13
(
b
) were observed.
OBJECT AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a molding device and a molding method which do not leave voids, weld lines or the like in a molded article, particularly when an optical semiconductor element is molded using a mold resin.
According to one aspect of the invention, there is provided a molding device comprising a cavity having first and second parts, at least one of the parts including at least one concave portion therein for molding an article having at least one convex portion therein, and a gate for injecting mold resin into the first and second parts of the cavity, the gate including at least one gate side portion for directly the mold resin into the part of the cavity having the at least one concave portion for molding a portion of the article having the at least one convex portion, and at least one plate-like gate base for injecting the mold resin in a substantially flat sheet state into the other part of the cavity for molding the other portion of the article.
According to another aspect of the invention, there is provided a method for molding an article, the method comprising the steps of providing a molding device having first and second parts defining a cavity, at least one of the parts including a concave portion, injecting mold resin into the concave portion of the at least one of the parts for molding a portion of the article including at least one convex portion, and injecting mold resin into the other of the first and second parts for molding another portion of the article having no convex portion, the injecting the mold resin into both of the first and second parts occurring substantially simultaneously.
REFERENCES:
patent: 4239724 (1980-12-01), Adell
patent: 4252294 (1981-02-01), Uchio
patent: 4554126 (1985-11-01), Sera
patent: 5635220 (1997-06-01), Izumi et al.
patent: 5723156 (1998-03-01), Matumoto
patent: 5750153 (1998-05-01), Shibata
patent: 5853771 (1998-12-01), Matsumoto
patent: 5904746 (1999-05-01), Okada
Hogg William N.
Luk Emmanuel
Silbaugh Jan H.
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