Semiconductor device manufacturing: process – Making device or circuit responsive to nonelectrical signal – Responsive to electromagnetic radiation
Reexamination Certificate
2000-04-26
2002-09-17
Smith, Matthew (Department: 2825)
Semiconductor device manufacturing: process
Making device or circuit responsive to nonelectrical signal
Responsive to electromagnetic radiation
C438S027000, C438S063000, C365S076000, C365S083000, C365S088000, C257S098000, C257S066000
Reexamination Certificate
active
06451622
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an optical device designed as a molded package with a hybrid-packaging of a plurality of components such as optical components and semiconductor elements on a lead frame. The present invention also relates to a method of manufacturing such an optical device.
RELATED ART
Heretofore, various optical devices and their peripheral components have been devised and developed for optical communication. A typical conventional optical device has two external terminals where one is for electrical signals and the other is for optical signals and a plurality of inner components such as optical components and semiconductor elements. The optical components include a photodiode (PD), a laser diode (LD), a planar lightwave circuit (PLC) board, an optical fiber, and so on, while the semiconductor elements include a preliminary amplifier for driving the LD and so on.
As an example of packaging, the optical device can be designed as a ceramic-packaged structure where the above components are housed in a ceramic housing and covered with a lid formed from metal, glass, ceramic or the like, or encapsulated with a resin.
FIG. 22
is a top view of a ceramic-packaged structure of one of the conventional optical devices. In the figure, the optical device
100
comprises a ceramic-package
111
in which optical components and the like are housed, a plurality of external terminals heads)
112
, an optical fiber cord
113
protruded through the side of the package
111
, and a plug connector
114
provided on the tip of the optical fiber cord
113
.
However, the problem is that such a structure of the conventional optical device is not suitable for mass production in automated facilities because of the optical fiber cord
113
protruding through the side of the ceramic package
111
. By the same token, there is another problem that high density mounting cannot be attained because of the following reasons. That is, the above structure of the conventional optical device is not suitable for a reflow-packaging, so that it is generally provided as of a dual inline package (DIP) type and mounted on a circuit board by inserting its external terminals or the like therein.
To solve the above problems, several approaches have been proposed so far to develop an optical device of the type that can be prepared by connecting an optical fiber cord to a package after mounting the package on a circuit board for input/output of optical signals. This kind of the structure can be seen in FIG.
23
.
FIG. 23
is a top view of the conventional optical device having such a ceramic-packaged structure of the conventional optical device. In addition to the components shown in
FIG. 22
, the optical device further comprises a ferrule
121
and a receptacle
122
. The ferrule
121
is optically coupled to the inner optical components and protruded from the package. The receptacle is responsible for holding an optical fiber cable to ensure an optical coupling between the optical fiber cable and the ferrule. By the way, it is noted that other parts are the same or like parts as those of
FIG. 22
, so that they have the same reference characters as those in FIG.
22
.
The configuration of the optical device shown in
FIG. 23
enables automation of its manufacturing system because a plug connector of an optical fiber (not shown) can be coupled to the receptacle
122
after mounting the package
111
on a circuit board. Therefore, it becomes possible to mount the optical device on the board by means of a re-flowing system.
In this case, however, the optical device is constructed as a ceramic packaged structure, so that there are some problems that the number of components is considerable and the manufacturing process is of high complexity. In addition, ceramic itself is expensive, so that the cost of manufacturing becomes high.
To solve the above problems, an optical device with a molded package in which inner components such as optical components and semiconductor elements are housed in a package and encapsulated with a molding resin by means of a transfer-molding technology has been proposed and developed so far.
FIG. 24
is a top view for illustrating a molded-package structure of the conventional optical device.
FIG. 25
is a top view for illustrating a configuration of the optical device shown in
FIG. 24
, from which a receptacle is being detached.
FIG. 26
is a cross-sectional view of the prime constituents of the optical device along the line XXVI—XXVI in FIG.
25
. In this case, the conventional optical fiber further comprises a ferrule-mounting portion
131
of a lead frame, a plurality of external lead terminals
132
protruded from both longitudinal sides of the lead frame, a ferrule
133
mounted on the ferrule-mounting portion
131
, an optical fiber
134
having one end portion on which the ferrule
133
is coaxially provided, an adhesive by which the ferrule
133
is bonded to the surface of the ferrule-mounting portion
131
, and a molding resin
136
that forms a receptacle-inserting guide, a receptacle-securing-portion, and so on. In addition, the reference numeral
137
denotes a receptacle and
138
denotes a split sleeve. A receptacle-inserting guide, a receptacle-fixing portion and so on for mounting the receptacle
137
are formed using a molding resin.
In such a conventional optical device, the lead frame and ferrule
133
are encapsulated with the molding resin
136
by means of transfer molding technique, where one end
133
a
of the ferrule
133
is externally protruded from the molding resin
136
. In addition, the ferrule
133
is placed on a flat surface of the ferrule-mounting portion
131
.
We are now going to explain the details of the process for manufacturing the conventional optical device.
To begin with, a lead frame with a plurality of the same patterns connected to each other is formed as shown in FIG.
27
. One of such patterns in the lead frame of
FIG. 27
is illustrated as an enlarged view in FIG.
28
. In the figure, the reference numeral
141
denotes a die pad,
142
denotes an inner lead,
143
denotes a dam bar,
144
denotes an outer frame portion, and
145
denotes a positioning hole. In addition, other components are the same or like components as those of
FIGS. 25 and 26
, so that they have the same reference characters as those of
FIGS. 25 and 26
.
Subsequently, the lead frame is subjected to a depressing process (or alternatively referred as a sinking process) by which areas indicated by “P1”, “P2”, “P3” and “P4” in
FIG. 28
are bent into a predetermined angle to lower the die pad
141
, and then each component is mounted on the lead frame.
After that, the lead frame is placed on a lower die having positioning pins. The pins are inserted into the positioning holes
145
on the lead frame to make sure that the lead frame is in the right place. Subsequently, an upper die is mated with the lower die to sandwich the lead frame between them.
FIG. 29
is a side view of such a configuration shown in the direction of the arrow “X” in FIG.
25
. In the figure, the reference numeral
146
denotes the upper die and
147
denotes the lower die. The upper die
146
and the lower die
147
have their own recesses. The recesses are symmetric with respect to the mating surface between them and each recess has a semicircle cross-sectional profile in the direction of the radius thereof. Thus, the recesses form a cylindrical-shaped opening when the upper and lower dies
146
,
147
are mated to each other. In addition, the opening has a slightly larger diameter than that of a ferrule
133
to leave a clearance of about 20 micrometers when the ferrule
133
is coaxially placed in the opening. Other components are the same or like components as those of FIG.
25
and
FIG. 26
, so that they have the same reference characters as those of these figures.
Subsequently, a molten molding resin is injected into a cavity formed between the upper die
146
and the lower die
147
and then cured within a fixed time period, followed by cutting the lead fr
Lee Granvill D
Smith Matthew
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