Measuring and testing – Fluid pressure gauge – With protective separator
Reexamination Certificate
1998-11-12
2002-03-05
Oen, William (Department: 2855)
Measuring and testing
Fluid pressure gauge
With protective separator
Reexamination Certificate
active
06351996
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to semiconductor pressure sensors, and specifically, to hermetic packaging of semiconductor pressure sensors.
2. Background Information
Today, most low-cost pressure sensor packages are designed to address clean gases and/or non-aggressive fluids.
FIG. 1
is a prior-art molded leadframe pressure sensor package
1
. The sensor package
1
includes a sensor die
2
that is attached to a housing
3
by a soft adhesive (e.g., RTV, epoxy, etc.), as shown by numeral
4
. The sensor package housing
3
is generally made out of a pre-molded plastic and includes a metal leadframe
5
for providing interconnection to external circuitry. The topside
11
of the pressure sensor is typically coated with a silicone gel
6
for communicating pressure from external gaseous media. The package further includes a lid
7
having an opening
8
for directing external pressure to the sensor. The silicone gel
6
provides a minimal amount of protection from gaseous media for the sensor, wire interconnects, etc. In the case of an absolute pressure sensor, pressure is applied from the topside
11
, whereas for gage or differential pressure sensing, a pressure port
10
is provided on the bottom side
12
.
However, this sensor package
1
has several drawbacks. First, since the sensor die
2
is attached to the housing
3
with a soft die attach material, the applied pressures from the bottom side
12
of the sensor die is typically limited to less than 150 pounds per square inch (“psi”). Second, the topside
11
of the sensor only supports inert gaseous with pressures limited again to less than 150 psi. This is because the pressure media that is applied to the topside
11
of the sensor will penetrate the intermediary coating (e.g., the silicone gel or other type of coating), causing reliability issues such as failure of the sensor over time or explosion of the silicone gel after rapid pressure changes. Third, the only use of fluid media with the sensor includes exposure to the fluid media from the bottom side
12
of the sensor. However, adhesives, soft or hard, are not considered hermetic and, over time, moisture and corrosive gases will penetrate the interface, causing the electronics of the pressure sensor to fail.
FIG. 2
is a typical prior art sensor package
20
for high pressure and fluid media compatibility. This type of sensor package
20
includes a sensor die
21
which is placed in a stainless steel housing
22
with hermetic glass feed-through pins
23
. The sensor die
21
has an integral glass or silicon constraint bottom
24
which provides a sealing cavity
25
therebetween for a vacuum reference and stress isolation from the housing. The die attach material is typically a soft epoxy such as RTV. A metal diaphragm
26
is welded to the stainless steel housing
22
and an inside cavity
27
formed therein is filled with oil to allow transfer of pressure to the sensor die
21
. This configuration isolates the sensor die
21
from the fluid media. The use of the metal diaphragm is the primary packaging technique available today for more demanding applications, with variations in pressure and ability to apply most fluids to the sensor package. However, this type of package only generally addresses specific applications and is very expensive.
Accordingly, there is a long-felt need in the sensor industry for a low-cost, long-term reliable solution to address the problems associated with conventional pressure sensors.
SUMMARY OF THE INVENTION
The present invention is a hermetic media interface for a sensor package. The hermetic media interface is incorporated into a pressure sensor package for interfacing directly to fluid and/or gaseous media. The pressure sensor package includes a semiconductor die and a pressure port that are housed in a pre-molded plastic package. In one embodiment, a eutectic solder is coupled between the semiconductor die and a metal pressure port to solder the same to the semiconductor die. The semiconductor die may be optionally metallized. In an alternative embodiment, the pressure port is made from one or more plastic materials and the pressure port is attached to the semiconductor die with an adhesive. An integral stress-isolation region may be optionally incorporated on the semiconductor die.
REFERENCES:
patent: 3247719 (1966-04-01), Chelner
patent: 3328649 (1967-06-01), Rindner et al.
patent: 3739315 (1973-06-01), Kurtz et al.
patent: 3994009 (1976-11-01), Hartlaub
patent: 4019388 (1977-04-01), Hall, II et al.
patent: 4023562 (1977-05-01), Hynecek et al.
patent: 4033787 (1977-07-01), Marshall
patent: 4040297 (1977-08-01), Karsmakers et al.
patent: 4050049 (1977-09-01), Youmans
patent: 4125820 (1978-11-01), Marshall
patent: 4129042 (1978-12-01), Rosvold
patent: 4229979 (1980-10-01), Greenwood
patent: 4236137 (1980-11-01), Kurtz et al.
patent: 4241325 (1980-12-01), Di Giovanni
patent: 4276533 (1981-06-01), Tominaga et al.
patent: 4295115 (1981-10-01), Takahashi et al.
patent: 4317126 (1982-02-01), Gragg, Jr.
patent: 4399707 (1983-08-01), Wamstad
patent: 4467656 (1984-08-01), Mallon et al.
patent: 4502335 (1985-03-01), Wamstad et al.
patent: 4609966 (1986-09-01), Kuisma
patent: 4655088 (1987-04-01), Adams
patent: 4656454 (1987-04-01), Rosenberger
patent: 4665754 (1987-05-01), Glenn et al.
patent: 4686764 (1987-08-01), Adams et al.
patent: 4737756 (1988-04-01), Bowman
patent: 4763098 (1988-08-01), Glenn et al.
patent: 4771639 (1988-09-01), Saigusa et al.
patent: 4773269 (1988-09-01), Knecht et al.
patent: 4790192 (1988-12-01), Knecht et al.
patent: 4800758 (1989-01-01), Knecht et al.
patent: 4842685 (1989-06-01), Adams
patent: 4879903 (1989-11-01), Ramsey et al.
patent: 4905575 (1990-03-01), Knecht et al.
patent: 4918992 (1990-04-01), Mathias
patent: 4942383 (1990-07-01), Lam et al.
patent: 4972716 (1990-11-01), Tobita et al.
patent: 4996627 (1991-02-01), Zias et al.
patent: 5064165 (1991-11-01), Jerman
patent: 5142912 (1992-09-01), Frische
patent: 5156052 (1992-10-01), Johnson et al.
patent: 5157972 (1992-10-01), Broden et al.
patent: 5172205 (1992-12-01), French et al.
patent: 5174156 (1992-12-01), Johnson et al.
patent: 5177579 (1993-01-01), Jerman
patent: 5178015 (1993-01-01), Loeppert et al.
patent: 5184107 (1993-02-01), Maurer
patent: 5186055 (1993-02-01), Kovacich et al.
patent: 5188983 (1993-02-01), Guckel et al.
patent: 5209118 (1993-05-01), Jerman
patent: 5220835 (1993-06-01), Stephan
patent: 5257546 (1993-11-01), Tobita et al.
patent: 5295395 (1994-03-01), Hocker et al.
patent: 5333504 (1994-08-01), Lutz et al.
patent: 5412994 (1995-05-01), Cook et al.
patent: 5438877 (1995-08-01), Vowles et al.
patent: 5454270 (1995-10-01), Brown et al.
patent: 5459351 (1995-10-01), Bender
patent: 5465626 (1995-11-01), Brown et al.
patent: 5477738 (1995-12-01), Tobita et al.
patent: 5483834 (1996-01-01), Frick
patent: 5509312 (1996-04-01), Donzier et al.
patent: 5515732 (1996-05-01), Willcox et al.
patent: 5539236 (1996-07-01), Kurtz et al.
patent: 5600071 (1997-02-01), Sooriakumar et al.
patent: 5646072 (1997-07-01), Maudie et al.
patent: 5684253 (1997-11-01), Bonne et al.
patent: 4227893 (1993-04-01), None
patent: 0 500 234 (1992-08-01), None
patent: 0 630 868 (1994-12-01), None
patent: 58039069 (1983-03-01), None
patent: 60233863 (1985-11-01), None
patent: 08153816 (1996-06-01), None
patent: 09126921 (1997-05-01), None
patent: 96/26424 (1996-08-01), None
Bryzek Janusz
Burns David W.
Cahill Sean S.
Nasiri Steven S.
Blakely , Sokoloff, Taylor & Zafman LLP
Maxim Integrated Products Inc.
Oen William
LandOfFree
Hermetic packaging for semiconductor pressure sensors does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hermetic packaging for semiconductor pressure sensors, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hermetic packaging for semiconductor pressure sensors will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2816599