Measuring and testing – Fluid pressure gauge – Diaphragm
Reexamination Certificate
2000-07-11
2002-06-11
Oen, William (Department: 2855)
Measuring and testing
Fluid pressure gauge
Diaphragm
Reexamination Certificate
active
06401542
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pressure sensing semiconductor device comprising a semiconductor chip which has a diaphragm formed with piezoresistance.
2. Description of the Background Art
FIG. 6
is a cross-sectional view showing the structure of a pressure sensing element
50
for use in conventional pressure sensing semiconductor devices. A semiconductor chip
101
includes a supporting part
101
a
and a diaphragm
101
b
. Piezoresistance
102
is located in the upper surface of the diaphragm
101
b
and surface electrode
103
are located on the upper surface of the supporting part
101
a.
The supporting part
101
a
of the semiconductor chip
101
is fixed on the upper surface of a seating
104
. The seating
104
has a through hole
105
formed under the diaphragm
101
b
and is fixed on a metal package
106
. The metal package
106
has a through hole
107
leading to the through hole
105
in the seating
104
. On the rear surface of the metal package
106
, a pressure leading-in tube
108
is provided which defines a through hole
113
leading to the through hole
107
in the metal package
106
. The metal package
106
also has leads
109
which are electrically connected by fine Au wires
110
to the surface electrodes
103
on the semiconductor chip
101
. The upper surface of the semiconductor chip
101
is coated with a moisture-proof resin
112
to cover the surface electrodes
103
and the Au wires
110
. Further, a metal cap
111
is welded to the metal package
106
to cover the semiconductor chip
101
together with the metal package
106
.
Although the pressure sensing element
50
shown in
FIG. 6
is a pressure sensor designed to detect absolute pressure, it may be a pressure sensor designed to detect pressure relative to atmospheric pressure by forming holes to open up atmosphere in the metal cap
111
.
FIG. 7
is a cross-sectional view showing the structure of a conventional pressure sensing semiconductor device. The pressure sensing element
50
shown in
FIG. 6
is mounted on a printed circuit board
120
. A control circuit component
121
for controlling the semiconductor chip
101
is further mounted on the printed circuit board
120
together with other circuit components such as a capacitor and a chip resistor. Further, a connector electrode
122
is soldered onto the printed circuit board
120
to establish electrical connections between the pressure sensing semiconductor device and external circuits. The control circuit component
121
and the connector electrode
122
are electrically connected to the leads
109
in the pressure sensing element
50
. Also, a metal shielding case
123
is soldered onto the printed circuit board
120
to cover the pressure sensing element
50
. The printed circuit board
120
and the metal shielding case
123
are surrounded by resin cases
124
,
125
in the shape of connectors leading to external circuits.
Since such a conventional pressure sensing semiconductor device requires, in addition to the pressure sensing element
50
, the printed circuit board
120
, the metal shielding case
123
, the resin cases
124
,
125
, and the like, it was difficult to do miniaturization of the device and to simplify the assembling process.
In addition, a limited space between the rear surface of the printed circuit board
120
and the resin case
125
prevents another metal shielding case
123
from being provided on the rear surface side of the printed circuit board
120
, and therefore especially the control circuit component
121
has low EMI tolerance.
SUMMARY OF THE INVENTION
A first aspect of the present invention is directed to a pressure sensing semiconductor device comprising: a semiconductor chip having a diaphragm formed with piezoresistance; a seating having a first main surface to which the semiconductor chip is fixed and in which a through hole is located at a point facing the diaphragm; a pressure leading-in tube of metal having a cylinder leading to the through hole in the seating and a flange having a first main surface fixed to a second main surface of the seating on the opposite side of the first main surface of the seating; and a metal substrate having a through hole in which the cylinder is inserted and a control circuit electrically connected to the semiconductor chip, the metal substrate being jointed to the flange by welding.
A second aspect of the present invention is directed to a pressure sensing semiconductor device comprising: a semiconductor chip having a diaphragm formed with piezoresistance; a seating having a first main surface to which the semiconductor chip is fixed and in which a through hole is located at a point facing the diaphragm; a pressure leading-in tube of metal having a cylinder leading to the through hole in the seating and a flange having a first main surface fixed to a second main surface of the seating on the opposite side of the first main surface of the seating; and a metal substrate having a through hole in which the cylinder is inserted, a control circuit electrically connected to the semiconductor chip, and a conductive pattern formed on a main surface facing the flange, the metal substrate being jointed to the flange by soldering the conductive pattern to a second main surface of the flange on the opposite side of the first main surface of the flange.
According to a third aspect of the present invention, in the device of the second aspect, at least either of the second main surface of the flange and a surface of the conductive pattern is plated to improve joint adhesion.
According to a fourth aspect of the present invention, the device of either of the first to third aspects further comprises: a metal cover fixed on the metal substrate to cover the semiconductor chip and the control circuit together with the metal substrate.
According to a fifth aspect of the present invention, the device of either of the first to fourth aspects further comprises: a glass cap fixed on the semiconductor chip and having a closed chamber to form a pressure standardized chamber on the diaphragm.
According to a sixth aspect of the present invention, in the device of either of the first to fifth aspects, the metal substrate further includes: a mounting part for mounting the pressure sensing semiconductor device to a target; and a connector electrode for establishing electrical connections between the pressure sensing semiconductor device and an external circuit.
A seventh aspect of the present invention is directed to a pressure sensing semiconductor device comprising: a semiconductor chip having a diaphragm formed with piezoresistance; a seating which has a through hole facing the diaphragm and to which the semiconductor chip is fixed; a pressure leading-in tube leading to the through hole; a substrate having a control circuit electrically connected to the semiconductor chip; and a glass cap disposed on the semiconductor chip and having a closed chamber to form a pressure standardized chamber on the diaphragm.
In accordance with the first aspect, the device can be miniaturized since none of the conventional metal package and resin cases is required.
In accordance with the second aspect, the device can be miniaturized since none of the conventional metal package and resin cases is required.
The device of the third aspect can improve joint adhesion of the metal substrate to the flange.
The device of the fourth aspect can improve EMI tolerance since the cover and the metal substrate are at the same potential.
The device of the fifth aspect permits single wafer processing in forming the glass cap, thereby improving productivity.
In accordance with the sixth aspect, the device can further be miniaturized.
The device of the seventh aspect permits single wafer processing in forming the glass cap, thereby improving productivity.
An object of the present invention is to provide a down-sized pressure sensing semiconductor device with improved EMI tolerance as compared with conventional ones.
These and other objects, features, aspects and adv
Mitsubishi Denki & Kabushiki Kaisha
Oen William
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