Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – Multiple housings
Reexamination Certificate
2001-11-20
2003-10-14
Cao, Phat X. (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
Multiple housings
C257S777000, C257S778000
Reexamination Certificate
active
06633078
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a semiconductor device in which semiconductor chips are mounted at a high density, a method for manufacturing an electronic equipment such as a portable information terminal in which the semiconductor device is mounted, an electronic equipment, and a portable information terminal.
BACKGROUND ART
Electronic equipments including a portable information terminal such as a mobile phone must be reduced in size, and in particular in thickness. Various methods for mounting a semiconductor chip have been proposed for such reduction in size. A particularly useful method among the proposed methods is a method in which two semiconductor chips are mounted on the top surface and the back surface of a wiring board so as to face each other. There are two methods as such a method for mounting the semiconductor chips on the top surface and the back surface of a single wiring plate.
The first method is a method in which a mounting/connecting substrate is provided between a wiring board and a mounting board, and the wiring board is connected to the mounting board through the connecting substrate, enabling a semiconductor chip on the back surface to be mounted without contacting the mounting board.
FIG. 11
is a cross-sectional view of a conventional electronic equipment mounted by such a method, for example, a cross-sectional view of a conventional electronic equipment disclosed in Japanese Laid-Open Publication No. 7-240496. As shown in
FIG. 11
, an electronic equipment is formed with a semiconductor device mounted on a mounting board
108
. The semiconductor device includes semiconductor chips
101
a,
101
b
respectively mounted on a top surface and a back surface of a single wiring board
103
. The wiring substrate
103
is bonded to, and electrically connected to, the mounting board
108
through a connecting substrate
106
. More specifically, electric connection between electrodes
104
of the wiring board
103
and electrodes
116
of the connecting substrate
106
as well as electric connection between the electrodes
116
of the connecting substrate
106
and electrodes
109
of the mounting board
108
are both implemented with solder bumps
107
. The thickness of the semiconductor chip
101
b
is herein set to a value smaller than the total thickness of the connecting substrate
106
and the solder bump
107
so that connection to the mounting board is not hindered. Note that the wiring substrate
103
is electrically connected to the first and second semiconductor chips
101
a,
101
b
through electrodes
102
. Moreover, the respective connections between the wiring board
103
and the first and second semiconductor chips
101
a,
101
b
and the connection between the wiring board
103
and the connecting substrate
106
are sealed with a sealing resin
105
.
The second method is a method in which a recess is formed at the back surface of a wiring board, and a semiconductor chip is fittingly mounted in the recess. This method also enables a semiconductor chip on the back surface to be mounted without contacting a mounting board.
FIG. 12
is a cross-sectional view of a conventional electronic equipment mounted by such a method, for example, a cross-sectional view of a conventional electronic equipment disclosed in Japanese Laid-Open Publication No. 10-79405. As shown in
FIG. 12
, a recess is formed at the back surface of the wiring board, and the semiconductor chip
101
b
is fittingly mounted in the recess. Mounting the semiconductor chip
101
b
in the recess enables connection between solder bumps
107
and electrodes of a mounting board (not shown) to be achieved without being disturbed by the semiconductor chip
101
b.
Note that the wiring substrate
103
is electrically connected to the first and second semiconductor chips
101
a,
101
b
through electrodes
102
. Moreover, the respective connections between the wiring board
103
and the first and second semiconductor chips
101
a,
101
b
are sealed with a sealing resin
105
.
The first and second methods thus enable the wiring substrate to be mounted on the mounting board so that the semiconductor chip on the back surface does not contact the mounting board.
However, the first method necessitates the use of an expensive connecting substrate, increasing the manufacturing costs of the electronic equipment. Moreover, since the wiring substrate is bonded to the mounting board through the connecting substrate, the total thickness is increased due to insertion of the connecting substrate, hindering reduction in thickness.
The second method necessitates formation of a recess in the wiring board, which requires special man-hour. Accordingly, this method also increases the manufacturing costs of the electronic equipment.
One possible way to mount on the mounting board the wiring substrate having a semiconductor chip mounted on both surfaces thereof without using any connecting substrate and without forming any recess in the wiring substrate is to reduce the thickness of the semiconductor chip
101
b
as much as possible. In this case, however, reduction in thickness of the semiconductor chip
101
b
reduces the rigidity, resulting in degraded reliability and the like.
Moreover, it is now assumed that the semiconductor chip
101
b
and the mounting board
108
have a small gap therebetween. In this case, even if the semiconductor chip
101
b
does not contact the mounting board
108
when mounted, the mounting board
108
may be subjected to bending or torsional stresses by external pressure and the like generated when the product is in use. This would cause the surface of the semiconductor chip
101
b
to contact the mounting board
108
, damaging the semiconductor chip
101
b.
Moreover, it is now assumed that the semiconductor chip
101
b
and the mounting board
103
have a small gap therebetween. In this case, even if the semiconductor chip
101
b
does not contact the mounting board
108
when mounted, the mounting board
108
may be subjected to bending or torsional stresses by external pressure and the like generated when the product is in use. This would cause the surface of the semiconductor chip
101
b
to contact the mounting board
108
, damaging the semiconductor chip
101
b.
DISCLOSURE OF THE INVENTION
The present invention is made to solve such conventional problems as described above, and it is an object of the present invention to provide a low-cost semiconductor device including a semiconductor chip mounted on both surfaces of a wiring board without degrading electric characteristics, a method for manufacturing an electronic equipment, an electronic equipment, and a portable information terminal.
A semiconductor device according to the present invention includes: a wiring substrate including electrodes on a top surface and a back surface thereof; projecting electrodes formed on one surface of the wiring substrate so as to have a prescribed height; a semiconductor chip having a thickness smaller than the height of the projecting electrodes and mounted on the one surface of the wiring substrate so as to be electrically connected to the electrodes of the wiring substrate; and an electronic component having a thickness larger than that of the semiconductor chip and mounted on the other surface of the wiring substrate as to be electrically connected to the electrodes of the wiring substrate so that the wiring substrate is warped to be recessed at the one surface.
In such a semiconductor device, the wiring substrate is warped toward the side having the projecting electrodes (bumps) (i.e., warped so as to be recessed on the side having the projecting electrodes). Therefore, the semiconductor chip will not contact the mounting board when the wiring substrate having the semiconductor chip mounted thereon is mounted on the mounting board, enabling the semiconductor chip to be mounted without being damaged. Moreover, neither the use of a connecting substrate nor formation of a recess in the wiring substrate is required, enabling the semiconductor device to be manufactured in
Hamaguchi Tsuneo
Kagata Kenji
LandOfFree
Semiconductor device, method for manufacturing an electronic... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Semiconductor device, method for manufacturing an electronic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor device, method for manufacturing an electronic... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3172701