Active solid-state devices (e.g. – transistors – solid-state diode – Incoherent light emitter structure – In combination with or also constituting light responsive...
Reexamination Certificate
2002-05-15
2004-05-18
Tran, Minhloan (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Incoherent light emitter structure
In combination with or also constituting light responsive...
C257S080000, C257S081000, C257S099000, C257S100000
Reexamination Certificate
active
06737680
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photocoupler, a method for fabricating the same, and a photocoupler fabrication apparatus. More particularly, the present invention relates to a photocoupler capable of reducing the mount area required to mount the photocoupler on an object, a method for fabricating such a photocoupler, and a photocoupler fabrication apparatus.
2. Description of the Related Art
The photocoupler is a device for removing noise generated in outputting a signal from an information processing unit such as a personal computer (PC) to external, and is soldered to a small card such as a personal computer memory card international association (PCMCIA) card connectable to an information processing unit.
A conventional photocoupler is shown in
FIGS. 30 and 31
.
FIG. 30
is a cross-sectional side view of the photocoupler, and
FIG. 31
is a schematic side view of a photocoupler fabrication apparatus.
The photocoupler, denoted by
8
a
, includes a pair of lead frames
83
and
84
. The lead frames
83
and
84
support a light-receiving device
81
and a light-emitting device
82
, respectively.
In more detail, the light-receiving device
81
and the light-emitting device
82
, which are placed to face each other on the same optical axis, are attached to the lead frames
83
and
84
, respectively, with bonding wires
85
such as gold wires. The light-emitting device
82
is pre-coated with a transparent silicone resin
86
for relieving stress at a junction and the like.
Transfer molding is then performed for the light-receiving device
81
and the light-emitting device
82
placed on the same optical axis, using a transparent resin. By the transfer molding, the light-receiving device
81
and the light-emitting device
82
are embedded in the light transparent resin to form a primary mold body
87
.
The primary mold body
87
is then shaped by burring and tie bar cut. The lead frames
83
and
84
protrude from the sides of the primary mold body
87
. The protruding lead frames
83
and
84
are then subjected to forming so that the base ends of the lead frames
83
and
84
are bent roughly at right angles with respect to the sides of the primary mold body
87
.
The thus-formed primary mold body
87
is placed in a mold space D of a photocoupler fabrication apparatus (hereinafter, simply called an apparatus)
9
as shown in FIG.
31
. The apparatus
9
is constructed of injection molds
91
and
92
. The injection mold
91
is laterally slidable.
A light-shading resin is injected into the mold space D of the apparatus
9
with the primary mold body
87
placed therein, to form a secondary mold body
88
by the transfer molding.
The secondary mold body
88
is shaped by burring and tie bar cut. The ends of the lead frames
83
and
84
protrude from the bottom of the secondary mold body
88
. Thus, the photocoupler
8
a
as shown in
FIG. 29
is fabricated.
The thus-fabricated photocoupler
8
a
is mounted on a small card by soldering using the ends of the lead frames
83
and
84
protruding from the bottom of the secondary mold body
88
.
With recent improvement in substrate wiring technology, objects on which devices are mounted, such as a small card, have not only enhanced in performance but also become smaller in size. In addition, the mount rate of devices to be mounted on an object, such as photocouplers, resistances, capacitors and transistors, on the object has increased. In view of these, it has become necessary to reduce the mount area required to mount each of such devices on the object.
However, to fabricate a photocoupler, consideration must be given to the following points: the double transfer molding for forming the primary mold body and the secondary mold body, the positional relationship between the lead frames supporting the light-receiving device and the light-emitting device inside the photocoupler, securing of a space for placing ends of the lead frames to be soldered to an object on which the photocoupler is mounted, and the like. The photocoupler therefore needs a body case large enough to satisfy these fabrication requirements, and thus reduction in the mount area required to mount the conventional photocoupler on an object is limited.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a photocoupler capable of reducing the mount area required to mount the photocoupler on an object by eliminating a structurally unnecessary portion, and an apparatus and method for fabricating such a photocoupler.
The present invention provides a photocoupler comprising:
a pair of lead frames;
a light-emitting device placed on one of the pair of lead frames;
a light-receiving device placed on the other lead frame for receiving light emitted from the light-emitting device;
a primary mold body made of a light transparent resin for covering the light-emitting device and the light-receiving device; and
a secondary mold body made of a light-shading resin for covering the primary mold body,
wherein the pair of lead frames are bent in the secondary mold body, and outer side faces of terminal portions ranging from the bent positions to top ends of the lead frames are exposed at surfaces of the secondary mold body.
According to the invention, the pair of lead frames are bent in the secondary mold body. The outer side face of the terminal portion of each of the lead frames, ranging from the bent position to the top end thereof, is exposed at the surface of the secondary mold body. That is, the outer side faces of the terminal portions are not covered with the secondary mold body, and thus the mold amount of the secondary mold body can be minimized. As a result, the mount area required to mount the photocoupler on an object can be reduced.
In the invention it is preferable that the secondary mold body has a concave portion, and a top end of the terminal portion protrudes from the concave portion.
For example, the concave portion is formed at a position corresponding to the top end of the terminal portion, so that the top end of the terminal portion protrudes from the concave portion. Therefore, soldering of the secondary mold body to an object for mounting can be made in the concave portion. This eliminates the necessity of securing a space for soldering near the secondary mold body, and thus the mount area required to mount the photocoupler on the object can be reduced.
In the invention it is preferable that a thermoplastic resin is used as the light-shading resin.
The present invention provides a photocoupler fabrication apparatus for fabricating the photocoupler described above, comprising:
a pair of fixing molds for fixedly sandwiching the primary mold body therebetween vertically;
a pair of lead frame pinch molds placed on both sides of the fixing molds for pinching base ends of the pair of lead frames; and
a bending mold placed on outer sides of the lead frame pinch molds for bending the pair of lead frames fixedly pinched by the lead frame pinch molds,
wherein the pair of fixing molds, the pair of lead frame pinch molds and the bending mold define a mold space for the secondary mold body.
According to the invention described above, with the construction of the pair of fixing molds, the pair of lead frame pinch molds and the bending mold, the secondary mold body can be molded into a desired shape, while the mold amount can be minimized. As a result, it is possible to fabricate a photocoupler in which the mount area of the body case constructed of the primary mold body and the secondary mold body can be reduced according to the shape of an object on which the photocoupler is to be mounted.
In the invention, it is preferable that correction means for correcting a position of the primary mold body with the bent lead frames in the mold space is provided.
According to the invention, with the correction means, when the primary mold body with the bent lead frames is not in a desired position, the primary mold body can be moved to the desired position. Therefore, it is possible to form the secondar
Birch & Stewart Kolasch & Birch, LLP
Sharp Kabushiki Kaisha
Tran Minhloan
Tran Tan
LandOfFree
Method and apparatus for fabricating a photocoupler with... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for fabricating a photocoupler with..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for fabricating a photocoupler with... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3238576