Measuring and testing – Fluid pressure gauge – Electrical
Reexamination Certificate
1999-07-29
2002-05-28
Fuller, Benjamin R. (Department: 2855)
Measuring and testing
Fluid pressure gauge
Electrical
C073S756000
Reexamination Certificate
active
06393922
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a pressure sensor component with a pressure connection element, in particular with a hose connection element, which can be mounted on the component-mounting top side of a printed circuit board. Such components are preferably surface-mounted (so-called SMD; SMD=surface mounted design) for space-saving reasons. The pressure measurement is usually carried out in accordance with the piezoresistive principle. Alternatively, it is possible to work with capacitive measurement principles. A semiconductor chip generally composed of silicon is used, as a rule, as the pressure sensor. In the case of piezoresistive measurement, the chip surface has arranged on it a thin silicon diaphragm electrically coupled to pressure-dependent resistors which are likewise formed in the silicon substrate and are connected in a bridge circuit. The semiconductor chip likewise comprises a circuit, assigned to the sensor, for amplification and correction of the signals and for trimming and for compensation of the sensor.
In order to measure the pressure, it is necessary to establish contact between the medium to be measured and the pressure sensor, that is to say the medium to be measured must be brought up to the sensor or the prevailing pressure must be transmitted to the sensor. Therefore, the pressure sensor is disposed in a housing which is open on one side. The pressure-sensitive surface of the sensor can thus make contact directly or indirectly with the medium to be measured. In order to prevent damage to the pressure sensor by the medium, it is customary to cover the surface of the semiconductor chip with a flowable filler, generally a plastic gel. The filler is chosen such that it passes on the pressure uncorrupted to the sensor.
If the medium to be measured is the medium which surrounds the pressure sensor component, the open pressure sensor component as such can be used. If the medium to be measured is not the same as the surrounding medium, the medium to be measured must be brought up to the sensor separately from the surrounding medium. For this purpose, use is usually made of a hose or tube system connected to the sensor component.
It has heretofore been customary in such cases to use pressure sensors embedded in a special housing with a hose connection. As a rule, these housings are considerably larger than the corresponding housings for the same sensor without a hose connection. This is disadvantageous both from cost standpoints and with regard to the subsequent application of the components. Moreover, the pressure sensor components with a hose connection obtainable heretofore have a defined connection diameter, which is fixed from the outset, with the result that the user of the pressure sensor is not left with any choice options in respect of the hose connection that is used.
A further disadvantage of the prior art pressure sensor components with a hose connection resides in the production of the components. The hose connection is fitted only after the open pressure sensor has been fully completed and the semiconductor chip has been covered with the filler. The hose connection is then bonded onto the pressure sensor component. In other words, an additional step, namely the permanent bonding of the hose connection, is necessary for the production process. In addition, it is necessary to test the adhesive bond in terms of its tightness. These additional steps are time and cost-intensive.
German published patent application DE 43 17 312 describes a pressure sensor with a pressure chamber arranged in a plastic housing. The pressure chamber has a tube connector which engages in a connection tube of a housing cover. It is described that at low pressures it may suffice to effect sealing between tube connector and connection tube with potting compound which is used to cover ceramic chip capacitors.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a pressure sensor component with a hose connection, which overcomes the above-mentioned disadvantages of the heretoforeknown devices and methods of this general type and which can be produced simply and cost-effectively. At the same time, the size of the housing should be kept as small as possible and, expediently, it should be possible to use the same base housing form as for a corresponding open sensor component without a hose connection. In addition, the pressure sensor component should be suitable for the connection of hoses of different diameter.
With the foregoing and other objects in view there is provided, in accordance with the invention, a pressure sensor component for mounting on a component-mounting surface of a printed circuit board, the component comprising:
a base body formed with a chip carrier and a semiconductor chip mounted on the chip carrier;
a flowable filler completely covering the base body;
a plurality of electrical connections to be routed out from the base body;
a tubular pressure connection element having an end fastened on the base body, the flowable filler filling interspaces formed between the end of the pressure connection element and the base body at least partially and sealing the pressure connection element gastightly against the base body.
In accordance with an added feature of the invention, the pressure connection element is fastened on the base body by an attachment selected from the group consisting of adhesive bonding, welding, and clamping.
In other words, the pressure sensor component according to the invention comprises a base body, which, in principle, may correspond to a customarily used open pressure sensor component, that is to say to a component without a hose attachment, and a pressure connection element matching the base body.
The distinctive feature of the invention is the fact that the base body and the pressure connection element are sealed with respect to one another with the flowable filler which is likewise used to fill the chip carrier and to cover the semiconductor chip. The base body is preferably configured to be open on one side and encompasses the semiconductor chip mounted on the chip carrier and connections which are contact-connected to said chip. The pressure connection element is advantageously placed onto the base body and encloses the opening in the base body in which the semiconductor chip is situated. This has the advantage that the filling of the chip carrier and hence the covering of the semiconductor chip and the sealing between base body and pressure connection element can be carried out together.
The flowable filler used is one which is sufficiently elastic to transmit pressures to the pressure sensor without corrupting the measurement results. With respect to the media usually to be measured, the filler should be largely chemically inert and be simple to handle. The filler is preferably a plastic gel, in particular a silicone-based gel.
As already mentioned, the base body of the pressure sensor component can, in principle, have any form and configuration which is usually used in the case of pressure sensor components which can be mounted on printed circuit boards. The base body expediently comprises a chip carrier made of plastic, in particular made of thermoplastic, which has an essentially planar chip carrier area on which the semiconductor chip with an integrated pressure sensor is arranged. Embedded in the plastic composition are a plurality of connections which project laterally from the chip carrier. The semiconductor chip and connections are contact-connected to one another in a customary manner for example by bonding wires. Alternatively, the chip can be arranged on a metallic lead frame having integrated connections. The chip carrier preferably has, at its edges, a side wall which has a height projecting above the chip surface and encloses the chip carrier. This side wall bounds the opening in the base body through which the medium to be measured is fed to the pressure sensor for the pressure measurement. The side wall of the base body expediently terminat
Aw-Musse Abdullahi
Fuller Benjamin R.
Greenberg Laurence A.
Infineon - Technologies AG
Lerner Herbert L.
LandOfFree
Pressure sensor component with hose connection does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pressure sensor component with hose connection, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pressure sensor component with hose connection will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2915085