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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical semiconductor device and an
optical semiconductor module equipped with it, and more particularly to
those with a low-profiled structure of the optical semiconductor device
which light is incident to or exits from. The present invention intends to
realize the compacting or low-profiling of the components using them.
2. Description of the Related Art
In recent years, multi-media components such as a "sub-note personal
computer", a portable information terminal, electronic still camera, etc.
are developing rapidly.
In addition, seven million portable components are sold in a year, and
about 80% of them adopt an infrared rays system in IrDA (Infrared Data
Association) standard. This system requires transmission/reception between
an external device and a main body using an infrared ray signal.
Therefore, a light emitting element for emitting infrared rays and a light
receiving element for receiving them are required.
Further, the optical head used in an optical recording/playing device such
as an "MD" or "CD" makes recording/reproducing information by irradiating
an optical recording medium with a beam and detecting the modulated beam
therefrom. In this case, the light emitting element and light receiving
element are required.
However, these light emitting elements and light receiving elements have
not been miniaturized sufficiently. FIG. 15 shows an example of a
semiconductor device equipped with an optical device which is disclosed in
Japanese Patent Publication. 7-28085. In FIG. 15, a semiconductor laser 1
is directly placed on a semiconductor substrate 2, and a prism 3 having a
trapezoidal sectional shape is secured on the semiconductor substrate 2.
Reference numeral 4 denotes an optical recording medium.
A slope 5 of the prism 3 opposite to the semiconductor laser 1 is a
semi-transparent reflecting face. A prism face 6 in contact with the
semiconductor substrate 2 constitutes a reflecting face at the other
portion than a photodetector (light-receiving element) 7. A prism face 8
opposite to the face 6 also constitutes a reflecting face.
A beam 9, which is emitted from the semiconductor laser 1 and is incident
on the prism 3 from the slope 5, is reflected from the reflecting faces 6
and 8, and detected by a photodetector 7.
On the other hand, FIG. 16 shows an infrared ray data communication module
11 incorporating an infrared ray LED, LED driver, PIN photodiode and an
amplifier, etc. In this module, light emitted from the LED 12 mounted on a
substrate is caused to exit through a lens 13. The light is incident on a
photodiode 14 mounted on the substrate through a lens 15.
The module as shown in FIG. 15, in which the optical component is mounted
above the semiconductor substrate, requires a very sophisticated technique
and is high in production cost.
In the module as shown in FIG. 16, emission or reception of light must be
made on a mold body and another semiconductor device must be set at an
opposite position. Therefore, the entire resultant system is increased in
thickness and cannot be miniaturized.
If the emission or reception of light in a horizontal direction is intended
in the module in FIG. 16, a lead 16 to the optical semiconductor device 11
must be bent at 90.degree.. The manner of bending the lead 11 influences
the stability of securing the semiconductor device 11.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an optical semiconductor
device which can be easily manufactured and easily miniaturized and
low-profiled.
Another object of the present invention is to provide an optical
semiconductor module equipped with such an optical semiconductor device.
Still another object of the present invention is to provide a method of
manufacturing such a semiconductor device.
A first aspect of the device is an optical semiconductor device of the
present invention which comprises:
a semiconductor chip having a light emitting face or a light receiving
face; and
a mold for molding said semiconductor chip, having a reflecting face
arranged to form a prescribed angle with said light emitting face or light
receiving face, wherein
an optical path of light exiting from or being incident on said
semiconductor chip is bent through said reflecting face.
A second aspect of the device is an optical semiconductor device according
to the first aspect, wherein said semiconductor chip is a chip having the
light receiving face,
said mold has the reflecting face arranged to cross a perpendicular line of
the light receiving face at a prescribed angle, and
said optical path is formed so that the light incident from a side of said
mold is bent by said reflecting face and incident on said light receiving
face.
A third aspect of the device is an optical semiconductor device according
to the first aspect, wherein
said semiconductor chip is a chip having the light emitting face,
said mold has the reflecting face arranged to cross a perpendicular line of
the light emitting face at a prescribed angle, and
said optical path is formed to exit at the prescribed angle with respect to
a light emitting direction through said reflecting face.
A fourth aspect of the device is an optical semiconductor device according
to the third aspect, wherein said semiconductor chip is connected to a
lead extended from a first side of said mold, and the light emitted from
the semiconductor chip is caused to exit through said reflecting face from
a second side of said mold opposite to said first side.
A fifth aspect of the device is an optical semiconductor device according
to the third aspect, wherein
said semiconductor chip is a chip having the light emitting face on its
side, and
the light emitted from said semiconductor chip is caused to emit through
the reflecting face from an upper face of said mold.
A sixth aspect of the device is an optical semiconductor device according
to the third aspect, wherein said mold is made of resin capable of
transmitting at least prescribed light, and a face formed in the mold
itself constitutes said reflecting face.
A seventh aspect of the device is an optical semiconductor device according
to the sixth aspect, wherein said reflecting face is a slope of the groove
formed in said mold.
An eighth aspect of the device is an optical semiconductor device according
to the first aspect, wherein
said mold is made of a hollow package of a first material not constituting
the optical path,
said package is provided in its opening with means made of a second
material capable of transmitting at least prescribed light and
constituting the optical path, and
a face formed in said means itself constitutes said reflecting face.
A ninth aspect of the device is an optical semiconductor device according
to the eighth aspect, wherein said first material is ceramic or metal, and
said second material is glass or resin capable of transmitting at least
prescribed light.
A tenth aspect of the device is an optical semiconductor device according
to the ninth aspect, wherein said reflecting face is a slope of the groove
formed in said second material.
An eleventh aspect of the device is an optical semiconductor device
according to the first aspect, which further comprises:
a lead frame having an island on which said semiconductor is placed; and a
lead electrically connected to said semiconductor chip and extended
externally from said mold, said lead being extended from a side opposite
to a side on which light is incident.
A twelfth aspect of the device is an optical semiconductor module including
the optical semiconductor device according to the first aspect, which
further comprises:
a supporting substrate on which said semiconductor chip is placed;
a lead electrically connected to said semiconductor chip and extended
externally from said supporting substrate, said lead being extended from a
side opposite to a side which light is incident on or exits from.
A thirteenth aspect of the device is an optical semiconductor module
according to the twelfth aspect,
wherein said semiconductor chip is provided with a first semiconductor
element section for emitting or receiving light and a second semiconductor
element section for driving it, and said second semiconductor element is
arranged in vicinity of said lead.
A fourteenth aspect of the device is an optical semiconductor module
according to the twelfth aspect, wherein the light emitting face or light
receiving face of said optical semiconductor chip is in parallel to a
surface of a substrate in which the optical semiconductor chip is mounted.
A fifteenth aspect of the device is an optical semiconductor module
according to the fourteenth aspect,
wherein the groove constituting said reflecting face is arranged so as to
oppose to a mounting substrate on which said optical semiconductor device
is placed, and
the optical path is formed to reach said light receiving face or light
emitting face through said reflecting face from a side perpendicular to
the upper surface of said mold.
A sixteenth aspect of the device is an optical semiconductor module
including a semiconductor device according to the first aspect, wherein
said semiconductor chip is composed of a single chip or a plurality of
chips.
A seventeenth aspect of the device is an optical semiconductor module
according to the thirteenth aspect,
wherein said substrate is built in an IC card, and optical communication is
carried out from a thinner side of the card.
An eighteenth aspect of the device is an optical semiconductor device
according to the first aspect,
wherein said semiconductor chip has an upper face serving as the light
receiving face, and
said mold is made of resin capable of transmitting at least prescribed
light, and has the reflecting face arranged to cross a perpendicular line
of the light receiving face at a prescribed angle, and a convex lens
provided integrally to the side of said mold.
A nineteenth aspect of the device is an optical semiconductor device
according to the sixteenth aspect, wherein said mold is provided with a
lead whose upper face is flush with an extreme end of said convex lens.
A twentieth aspect of the device is an optical semiconductor device
according to the sixteenth aspect,
wherein a vertical segment composed of a lowest end of said convex lens and
a focal point of said lens crosses said reflecting face.
A twenty-first aspect of the method is a method of manufacturing a
semiconductor device of the present invention which comprises the steps
of:
arranging a mounting substrate on which a semiconductor chip having a light
receiving face or light emitting face is mounted within a space formed by
an upper die and a lower die; and
injecting resin capable of transmitting at least prescribed light into the
space to mold said semiconductor chip to provide a resin mold, wherein
said upper die has an inner wall located to cross a perpendicular line to
the light receiving face or light emitting face and constitutes a
reflecting face formed in said resin mold, and
said resin mold is provided in such a manner that the resin is injected in
the space in a state where an extreme end in a protruding direction of a
lens portion integrally molded to the side of said resin mold is
substantially aligned with a junction of said upper die or lower die.
A twenty-second aspect of the method is a method of manufacturing an
optical semiconductor device according to the twenty-first aspect, wherein
said inner wall is mirror-finished and the remaining portion is
satin-finished.
In accordance with the first to fifth inventions, an optical semiconductor
device comprises a semiconductor chip having a light emitting face or a
light receiving face; and a mold (sealing body) for molding (sealing) the
semiconductor chip, having a reflecting face arranged to form a prescribed
angle with the light emitting face or light receiving face. In addition,
an optical path of light exiting from or being incident on the
semiconductor chip is bent through the reflecting face.
In this configuration, the optical semiconductor device can be miniaturized
and low-profiled.
Particularly, since light can be incident or exit through the reflecting
face from the side of the mold, the optical semiconductor device can be
further low-profiled. Further, by integrally or individually providing the
mold with means having the reflecting face, with the optical semiconductor
device located horizontally, the incident light or exit light can be made
horizontal. The positioning precision of the optical path can be improved.
If these optical semiconductor devices are located at opposite sides,
optical communication can be carried out horizontally.
The light can be caused to exit through the reflecting face from the upper
face of the mold. Therefore, by integrally or individually providing the
mold with means having the reflecting face, with the optical semiconductor
device located horizontally, the incident light or exit light can be made
vertical. This permits the optical semiconductor device to be manufactured
at very low cost.
In accordance with the sixth invention, the mold is made of resin capable
of transmitting at least prescribed light, and a face formed in the mold
itself constitutes the reflecting face. Therefore, the reflecting face can
be formed simultaneously with the process of resin molding the
semiconductor chip. This makes the prism as shown in FIG. 15 unnecessary.
Thus, the process of assembling the optical semiconductor device can be
simplified and the production cost can be reduced. A module which can be
obtained by mounting the optical semiconductor device on a substrate such
as a printed board can be low-profiled.
In accordance with the seventh invention, the slope of the groove formed in
the mold serves as the reflecting face. Therefore, the reflecting face can
be easily formed by only providing a convex portion constituting the
groove in a molding die. The molding die itself can be simplified.
Further, the reflecting face can be mirror-finished by polishing the
groove.
In accordance with the eighth invention, the mold is made of a hollow
package of a first material not constituting the optical path, and the
package is provided in its opening with means made of a second material
capable of transmitting at least prescribed light and constituting the
optical path, and a face formed in the means itself constitutes the
reflecting face.
In accordance with the ninth invention, when a hollow package made of
ceramic, metal, or resin is used as the mold, means constituting the
optical path made of glass or resin is provided as shown in FIGS. 7 and 8.
Thus, the exit light or incident light can be made horizontal.
In accordance with the tenth invention, the reflecting face is constructed
of a slope of the groove formed in the second material.
In accordance with the eleventh invention, the semiconductor chip is placed
on an island (a die-pad) of a lead frame, and a lead is extended
externally from the island through a side opposite to the side on which
light is incident. In this configuration, the reflection of light through
the lead frame or metallic lead removes optical noise.
In accordance with the twelfth invention, the semiconductor chip is placed
on a supporting substrate such as a ceramic substrate, a printed board or
a metallic substrate with its surface insulated, and a lead is extended
externally from the substrate through the side opposite to a side on which
light is incident. In this configuration, the reflection of light through
the lead frame or metallic lead removes optical noise.
In accordance with the thirteenth invention, the semiconductor chip is
provided with a first semiconductor element section for emitting or
receiving light and a second semiconductor element section for driving it,
and the second semiconductor element is arranged in vicinity of the lead.
In this configuration, the second semiconductor element section does not
serve as the optical path so that this section can be used as a region for
extending the lead or metallic wires. This eliminates necessity of taking
optical noise owing to light reflection into consideration.
In accordance with the fourteenth invention, since the optical
semiconductor is horizontally mounted on a substrate, a module having a
low-profiled or simple structure can be manufactured at low cost.
An optical IC using the such a module can be low-profiled at low cost.
In accordance with the fifteenth invention, the groove is arranged on the
side of the substrate for mounting, and the semiconductor chip is
sandwiched between the substrate for mounting and island or supporting
substrate. This implements optical detection with no optical noise and
with high reliability.
In accordance with the sixteenth invention, the semiconductor chip has a
light emitting function and a light receiving function so that an optical
module which is miniaturized and has a high level of function can be
obtained.
In accordance with the seventeenth invention, building the substrate in an
IC card provides a very low-profiled and high reliable optical module.
In accordance with the eighteenth invention, since a convex lens formed by
integral molding is provided on the side of the mold, a miniaturized
optical module with high light convergence can be obtained.
In accordance with the nineteenth invention, the upper face of the lead is
flush with an extreme end of the convex lens. Therefore, with no burr in
resin molding, a highly reliable optical semiconductor device can be
obtained.
In accordance with the twentieth invention, the groove is deeply formed so
that the virtual segment crosses the reflecting face, thereby implementing
the reflection with high efficiency.
In accordance with the twenty-first invention, the extreme end in a
protruding direction of the lens portion is substantially aligned with a
junction of the upper die and lower die for molding the resin mold. Thus,
the parting or separating property of a mold product can be improved so
that the optical semiconductor device with high reproducibility can be
manufactured very easily.
In accordance with the twenty-second invention, the inner wall of the
molding die is partially mirror-finished or satin-finished so that the
reflecting face can be very easily formed with high selectivity and
reproducibility.
The above and other objects and features of the present invention will be
more apparent from the following description taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A, 1B and 1C are a plan view, a sectional view and another sectional
view of an optical semiconductor device according to a first embodiment of
the present invention;
FIG. 2 is a sectional view of the optical semiconductor device for
explaining a groove shown in FIG. 1;
FIGS. 3A, 3B, 3C and 3D are a plan view, a sectional view and sectional
views of an optical semiconductor device according to a second embodiment
of the present invention;
FIG. 4 is a plan view for explaining a lead frame shown in FIGS. 3A-3D;
FIG. 5 is a sectional view of means constituting a reflecting face
according to a third embodiment of the present invention;
FIG. 6 is a sectional view of an application of the optical semiconductor
device to a hybrid substrate;
FIG. 7 is a sectional view of an application of the optical semiconductor
device to a ceramic package;
FIG. 8 is a sectional view of an application of the optical semiconductor
device to a can type package;
FIG. 9 is a sectional view of an application of the optical semiconductor
device to a IC card;
FIG. 10 is a schematic plan view of FIG. 9;
FIG. 11 is a perspective view showing the relationship between the IC card
and a computer;
FIG. 12 is a view for explaining the manner of mounting the optical
semiconductor device on a circuit board arranged three-dimensionally;
FIG. 13 is a view of an application of the optical semiconductor device to
an optical pick-up;
FIG. 14 is a view of another application of the optical semiconductor
device to an optical pick-up;
FIG. 15 is a module in which a conventional optical semiconductor device
and an optical device are combined;
FIG. 16 is a schematic view of another conventional optical semiconductor
device;
FIG. 17 is a schematic view of a conventional optical semiconductor device
attached to a circuit board;
FIG. 18 is a view of an optical semiconductor device according to the
fourth embodiment of the present invention;
FIG. 19 is a view of an optical semiconductor device according to another
embodiment of the present invention;
FIGS. 20 and 21 are views showing the shape of a lens used in the present
invention;
FIG. 22 is a view for explaining the method of molding the optical
semiconductor device according to the present invention;
FIG. 23 is a view for explaining a problem in the method of molding the
optical semiconductor device according to the present invention;
FIG. 24 is a view for explaining the manner of setting an optical
semiconductor device according to the fifth embodiment in a substrate;
FIG. 25 is a view for explaining the details of the optical semiconductor
device;
FIG. 26 is a view for explaining a groove shown in FIG. 25; and
FIG. 27 is a view for explaining the optical semiconductor device according
to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiment 1
Now referring to FIG. 1, an explanation will be given of the first
embodiment of the present invention.
FIG. 1A is a plan view of an optical semiconductor device according to the
first embodiment of the present invention; FIG. 1B is a sectional view
taken in line A--A in FIG. 1A, and FIG. 1C is a sectional view taken in
line B--B in FIG. 1A.
The optical semiconductor device includes a lead frame composed of an
island 21 indicated by two-dot chain line and leads 22 provided in the
vicinity of island 21, light-emitting and light-receiving semiconductor
chips 23 and 24, indicated by one-dot chain line, loaded on the island 21
and a mold 25 with a groove formed on its upper surface covering the lead
frame and semiconductor chip on their periphery. Light is incident on an
inner wall 26 of the groove 27 serving as a reflecting face from the side
of the optical semiconductor device. The light is further incident on the
light receiving face of the light-receiving semiconductor chip 24. On the
other hand, the light emitted from the light-emitting semiconductor chip
23 is reflected from the inner wall 26 of the groove and guided to the
side of the mold. The lead frame is made of Cu. The semiconductor chips 23
and 24 are secured on the lead frame by fixing means such as soldering.
The semiconductor chip 23 may be a light emitting element such as an
infrared ray LED and a laser. A driving circuit for the light emitting
element is integrated on the light receiving semiconductor chip 24. The
light emitting element and its driving circuit may be integrated. The
infrared ray LED, whose light emitting face is an upper face of the chip,
is arranged horizontally on the island as seen from FIG. 1B. The
semiconductor laser, from the side of which light is emitted, requires no
groove. However, for convenience of fabrication, the groove may be also
formed on the light emitting semiconductor chip 23.
The light receiving semiconductor chip 24 may be a photo-sensor of e.g. a
PIN diode. The PIN diode may be integrated to its driving circuit, or may
be integrated to the driving circuit for driving the LED or laser. Bonding
pads are formed on the periphery of these semiconductor chips.
Correspondingly, a plurality of leads 22 are extended externally from the
periphery of these chips. The bonding pads are connected to the lead wires
through fine metallic wires. The mold 25 may be made of any material which
is optically transparent. Specifically, the material may be resin which
can transmit the light having the wavelength used, for example, infrared
rays which are generally emitted from the LED. The tips of the leads 22
and the semiconductor chips are molded by the mold 25 which is optically
transparent. The groove 27 having the reflecting faces 26 is formed in the
mold 25.
The most important feature of this embodiment resides in the reflecting
face 26 which is provided by forming the groove 27 in the mold 25. The
reflecting face 26 permits light to be incident from the side E of the
mold 25 and to exit therefrom.
Generally, the semiconductor chip which constitutes a light-emitting
section or a light receiving section must be provided with a prism and a
lens on its surface. Therefore, the module or set using such a
semiconductor chip has an increased thickness in a vertical direction. In
addition, because an optical device is arranged on the surface or
periphery thereof, the module or set is difficult to be low-profiled or
miniaturized. On the other hand, in accordance with the present invention,
because of the reflecting face 26, incidence or exit of light can be made
through the side E of the mold. Therefore, the prism is not required, and
the lens can be provided at the side E of the mold as occasion demands.
Specifically, as shown in FIG. 3, a convex lens may be integrally or
individually formed on the side of the transparent mold. Thus, an increase
in the thickness of the set or module can be suppressed. Particularly,
where the laser beam having a small diameter is dealt with, the groove
itself may be shallow so that the module can be further miniaturized or
low-profiled.
The lead frame is made of Cu, and has a thickness of about 0.125 mm. The
semiconductor chip has a thickness of about 250-300 .mu.m. The mold 25 is
formed by e.g. transfer molding technique using a transparent epoxy
material, and has an entire thickness of about 1 mm-1.5 mm. The thickness
of the mold 25 can be further decreased according to the thickness of the
semiconductor chip. Since the die has an area where the groove is to be
formed, when the semiconductor chip is transfer-molded, the groove is
simultaneously formed.
The groove 27 may have any optional thickness as long as the semiconductor
chip is not exposed and the reflecting face is formed. For example, the
depth of the groove 27 is half the thickness of the mold 25, i.e. about
750 .mu.m. The reflecting face 26 of the groove 27 is sloped by 45.degree.
with respect to the bottom face of the optical semiconductor device. The
depth of the groove 27 is desired to be in a range of 20-30 .mu.m. The
reflecting face constitutes a reflecting plane because of a difference in
the refractive index between the air and transparent resin on both sides
of the boundary. However, in order to realize total internal reflection,
the reflecting face may be covered with a metallic film.
Such a metallic film can be formed by means of vapor deposition and
sputtering which are commonly used in the semiconductor technology. The
metallic film can be also formed by plating. In this case, care should be
taken of short-circuiting between the metallic film and the semiconductor
chip or leads. The former two techniques require a mask for this purpose.
Where the entire body is dipped in a plating solution in an electroless
plating, the extended portions of the leads 22 and the mold 25 are
previously covered with a resin film, and this resin film may be removed
after the plating. The metallic film may be formed by dropping the
solution on only the groove rather than the dipping of the entire body.
The metallic film is made of Au, Al, Ni, etc.
Meanwhile, a molding die is formed by electric spark machining and
satin-polished in view of the parting property of the mold product.
Therefore, if the portion of the molding die corresponding to the
reflecting face is mirror-polished, the corresponding portion of the mold
product constitutes a mirror face, and hence may be used in the above
reflecting face. The mirror face may be further covered with another
metallic film. The side E, through which light travels, may be preferably
mirror-polished.
In this embodiment, the leads can be arranged on the sides F, G and H other
than the side E through which light travels. However, in view of the
reflection of light by the metallic wires or leads, the leads are
preferably arranged on the side H. As seen from the plan view of FIG. 1A,
the light receiving section 24 includes a substantial light-receiving
element area (first area) on the right side and a driving element area
therefor (second area). In this case, since light does not travel through
the second area, this area can be used as the area for extending the leads
or pulling the metallic wires, thereby preventing noise by light
reflection from invading the first area. Since the first area is displaced
towards the right side, the groove 27 is necessarily displaced toward the
right side. The area on the left side of the groove can be assured as an
area for extending the metallic wires. If the first area is located on the
center or left side, the metallic wires may be extruded from the groove.
The optical semiconductor device described above can be mounted on e.g. a
printed substrate, ceramic substrate, insulating metallic substrate, or
resin film such as TAB or FPC so that it is arranged horizontally. Thus, a
low-profiled module or system can be provided.
For example, if an IC card equipped with such a semiconductor device
permits the thickness of the card itself to be reduced and communication
of an optical signal to be carried out on the one side thereof.
Meanwhile, the island 21 is divided into two sections as indicated by
two-dot chain line, but may be integrally formed. The mold 25 molds the
two semiconductor chips integrally, but may mold these semiconductor chips
individually. Further, the two semiconductor chips are may be fixed on the
one island and may be individually molded. The lead frame may be
individually molded as a discrete component.
The minimum square areas encircled by one dotted chained line are areas on
which light is incident or from which light emits.
FIG. 2 is a sectional view of the optical semiconductor device showing a
modification of the groove shape. As seen from FIG. 2, one reflecting face
30 of the groove 27 is vertical. In this case, in comparison with the
groove shape in FIG. 1, the left area of the groove can be assured to
which the metallic wires can be extended. The second area described above
can be extended to the vicinity of the reflecting face 30. In this case,
if the reflecting face is vertical, the parting property of the mold
product is promoted so that the reflecting face is preferably sloped left.
Embodiment 2
FIGS. 3A to 3D show a modification of the optical semiconductor device of
FIG. 1. FIG. 3A is a plan view. FIG. 3B is a side view viewed from the
left side. FIG. 3C is a sectional view taken in line A--A in FIG. 3A and
corresponds to a photo IC. FIG. 3D is a sectional view taken in line B--B
in FIG. 3A and corresponds to a light emitting diode.
FIG. 4 is a view showing the state where a photodiode and an LED are
mounted on the lead frame of the optical semiconductor device as described
above.
As seen from FIG. 4, leads 22 are extended on only the left side of an
island 21. The leads each has an enlarged portion 30 at its tip. On the
left side and lower side of an IC chip, bonding pads are formed. The
enlarged portion 30 and the bonding pad are electrically connected by
bonding wires. An island 31 where the LED is located has a cup-shape as
shown in FIG. 3D so that light can fly upwards. The cup has sloping sides.
The light having flied in other directions than upwards are focused by the
sloped sides and thereafter guided upwards effectively. For example, it is
similar to a reflecting plate (collector) which is formed on the periphery
of a midget light bulb of a portable lamp. A PIN photodiode is formed on
the light emitting area 24. On the periphery of the photodiode, a driving
IC is formed. An LED driving circuit is formed in the vicinity of the
connecting portions of two wires extended from the LED. The square area
indicated by dotted line is a resin molding region.
A detailed explanation will be given of the optical semiconductor device
according to this embodiment. As apparent from FIG. 3A, two grooves each
constituting a reflecting face are formed. A wall body 32 is formed
between these two grooves so as to separate them from each other. The
groove may be formed continuously from the one side to the other side like
FIG. 12. However, if external force is applied to such a structure, some
crack may be generated at the bottom of the groove. In order to overcome
such an inconvenience, a frame is formed so as to surround the photo IC
and LED, thereby improving the strength of the mold. The face of the
groove other than reflecting face is sloped at a certain angle in order to
improve the parting property after molding (extracting property of the
molded optical semiconductor). In order to improve the parting property of
the mold product, the external shape is also sloped at a certain angle so
that it is not in parallel to the drawing direction.
Lenses L each having a sectional sphere shape are provided on the side E.
Each lens L may be elliptical lens. The optical semiconductor device
according to this embodiment is used for an IrDA. Therefore, the lens for
the upper light receiving element is designed so that an external optical
signal can be effectively guided to the light receiving element and light
enters the light detecting area of the light receiving element. The lens
for the lower light emitting element is designed so that the emitted light
can reach the detecting area of another optical semico | | |
