Source: http://www.google.fr/patents/US7900520
Timestamp: 2013-06-18 06:58:16
Document Index: 314171823

Matched Legal Cases: ['art 11', 'art 12', 'art 12', 'arts 23', 'art 12', 'art 107', 'art 107', 'art 12', 'art 12', 'art 12', 'art 103', 'art 11', 'art 11', 'art 11', 'art 11', 'art 12', 'art 11', 'art 11', 'art 11', 'art 11']

Brevet US7900520 - Pressure sensor device - Google�BrevetsRecherche Images Maps Play YouTube Actualit�s Gmail Drive Plus » Recherche avanc�e dans les brevets | Historique Web | Connexion Recherche avanc�e dans les brevets BrevetsA semiconductor pressure sensor for a pressure sensor device has a pressure detection element which includes a membrane made of semiconductor material, particularly silicon. The sensor includes a support having a three-dimensional body passed through by a detection passage. The detection element is made...http://www.google.fr/patents/US7900520?utm_source=gb-gplus-shareBrevet US7900520 - Pressure sensor device Num�ro de publicationUS7900520 B2Type de publicationOctroi Num�ro de demande12/487,347 Date de publication8 mars 2011 Date de d�p�t18 juin 2009 Date de priorit�19 juin 2008Autre r�f�rence de publicationEP2136193A2, US20090314096 Num�ro de publication12487347, 487347, US 7900520 B2, US 7900520B2, US-B2-7900520, US7900520 B2, US7900520B2 InventeursPaolo Colombo Cessionnaire d'origineEltek S.P.A.Citations de brevets (8), Classifications (8) Liens externes: USPTO, Cession USPTO, EspacenetPressure sensor deviceUS 7900520 B2 R�sum� A semiconductor pressure sensor for a pressure sensor device has a pressure detection element which includes a membrane made of semiconductor material, particularly silicon. The sensor includes a support having a three-dimensional body passed through by a detection passage. The detection element is made integral with a first end face of the three-dimensional body, substantially at a respective end of the detection passage. The support is configured to serve the function of a mechanical and/or hydraulic adaptor or interface, with the aim of mounting the sensor into a pressure sensor device, particularly to allow mounting the pressure sensor into a pressure sensor device configured for mounting a sensor of the type referred to as monolithic or ceramic.
�two-shot moulding� plating; and
�Laser Direct Structuring�.
associating to the support electrical connection means for the detection element, the support being configured to also serve the functions of an electrical adaptor or interface with the aim of mounting the sensor into a pressure sensor device. Description
CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority from Italian patent application No. TO2008A000485, filed on Jun. 19, 2008, and European Patent Application No. EP 09162876.8 filed Jun. 16, 2009, the entire disclosures of which are incorporated herein by reference.
FIELD OF THE INVENTION The present invention refers to a pressure sensor device and to a semiconductor pressure sensor for making such device. Devices of the mentioned type are used in various industries for detecting the pressure of fluids (liquid and aeriform), such as in the automotive industry, household and household appliances industry, air conditioning and in the hydro-sanitary-heating industry in general.
BACKGROUND ART These detection devices typically comprise a casing, defining a chamber having an inlet for a fluid to be subjected to pressure measurement, a pressure sensor accommodated in the casing and a circuit arrangement, to which the pressure sensor is electrically connected; the circuit arrangement typically includes a printed circuit board at least partially accommodated in the chamber of the casing.
Two types of sensors, referred to herein as �monolithic sensors� and �semiconductor sensors� for the sake of simplification, are mainly used for the production of the indicated detection devices. The characteristic that immediately distinguishes the two types of sensors are the dimensions, the semiconductor sensors being definitely smaller with respect to monolithic sensors.
A typical monolithic sensor is schematically represented in FIGS. 1 and 2, where it is indicated in its entirety with 1. Such sensor typically comprises a monolithic body 2, generally cylindrical shaped and usually made of ceramic material (as a matter of fact, sensors of the type in question are also referred to as �ceramic sensors�). The monolithic body 2 has a blind cavity 3, having a substantially circular section, closed at an end by a membrane portion 4 of the monolithic body 2. An electrical detection component, capable of generating a signal representing a flexure of the membrane portion 4, is provided for at the membrane portion 4; the components used for such purpose are typically selected from among resistor elements, capacitive elements and piezo-resistive elements. The detection component (or a group of such elements) is mounted on a printed circuit board, indicated with 5 in FIG. 1, provided with terminals or pins 5 a, which is fixed on the face of the monolithic body 2 opposite to the opening of the cavity 3, in such a manner that the detection element adheres to the surface of the membrane portion 4 outside the cavity 3, so as to be able to detect any flexures thereof.
The sensor body is in this case made up of a so-called �die�, i.e. a small block or plate made of semiconductor material, typically silicon, which defines a detection membrane. Also the die of a semiconductor pressure sensor may be made in such a manner to define a small cavity closed at an end by a respective membrane portion, or the die may form the membrane alone and be fixed, for example glued, on a respective substrate, typically made of glass, defining an axial cavity.
Directly obtained on the die made of semiconductor material is the miniaturised electric circuit of an integrated circuit serving to detect the degree of deformation of the detection membrane. The die may also be enclosed in a respective casing or container, referred to as �package�, projecting from which are the connection terminals (pins), conceived to connect the die itself to a circuit support, of the printed circuit board intended to be mounted inside the respective pressure sensor device.
SUMMARY OF THE INVENTION An aim of the present invention is that of providing a semiconductor pressure sensor that is easy to make, reliable in use, easier to use and more flexible with respect to homologous sensors of the known type. Another aim of the present invention is that of providing a semiconductor pressure sensor of a particularly advantageous construction regarding the manufacture of a pressure sensor device. Another aim of the invention is that of providing a pressure sensor device, comprising a semiconductor pressure sensor, that is easier to manufacture with respect to the prior art. Another aim of the invention is that of providing a pressure sensor device, comprising a semiconductor pressure sensor, that is easy to mount and functionally reliable over time. Another aim of the invention is that of providing a pressure sensor device, comprising a semiconductor pressure sensor, whose assembly may be attained at least partially in an automated manner, without risks of damaging the most delicate components of the device itself, but guaranteeing the required mounting accuracy. Another aim of the present invention is that of providing a semiconductor pressure sensor particularly advantageous with the aim of attaining at least one of the previously outlined aims.
BRIEF DESCRIPTION OF THE DRAWINGS Further objects, characteristics and advantages of the present invention shall be apparent from the detailed description that follows and from the attached drawings, strictly provided for exemplifying and non-limiting purposes, wherein:
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION In its essence, the idea on which the present invention is based is that of providing a semiconductor pressure sensor including a �dedicated� support aimed at facilitating the mounting and manipulation of the sensor itself, particularly with the aim of manufacturing a pressure sensor device. The abovementioned support forms an integral part of the sensor, representing a substrate for the respective detection part, which includes a die made of semiconductor material, provided with a miniaturised circuit, and possibly with its own package. The support is configured to provide, at the same time, mechanical and/or hydraulic interface functions with the aim of mounting and hydraulic connection of the sensor inside a detection device.
According to a further aspect, per se independently inventive, the support of the sensor according to the invention serves the functions of an adaptor. As a matter of fact, from a first point of view, the support may be configured depending on its final application, or depending on the configuration of the casing of a detection device on which the sensor itself is to be mounted, and this regardless of the embodiment of the detection part of the sensor, which remains unaltered or substantially unaltered. From a second point of view, the support may be configured to adapt, in terms of shape and/or dimensions, a pressure sensor of one first type to the shape and/or dimensions of a pressure sensor of a different type. Therefore, from this second point of view, the support of the sensor according to the invention represents an adaptor, which transforms the abovementioned pressure sensor of the first type to the shape and/or dimensions of the abovementioned pressure sensor of second type. In an advantageous embodiment, the support is substantially configured as the body of a pressure sensor of the type defined previously as �monolithic sensor�. Through this particular embodiment, a semiconductor sensor according to the invention may be alternatively mounted on a casing of a sensor device conceived for mounting a monolithic sensor. This entails clear advantages for the manufacturer, in terms of product standardisation, given that semiconductor sensors or monolithic sensors may be used on a same device casing without distinction; furthermore, in this manner, a same assembly line may be used for manufacturing the two different types of pressure sensor devices.
The part 11, hereinafter also referred for as �adaptor support� for the sake of simplification, is substantially configured three-dimensionally as the body of a monolithic sensor, though having some substantial differences. The body of the adaptor support 11, preferably generally cylindrical-shaped, has an axial cavity, indicated with 13 in FIG. 7, open on a first end face of the body itself, such cavity having a bottom surface and a peripheral or circumferential surface; preferably, the cavity 13 has a circular section. The two faces of the support 11 are spaced from each other in an axial direction of the sensor 10, identifying the thickness, or the height of the support 11; the axis of the sensor 10, indicated with A in FIG. 7, represents in the illustrated example also a preferential mechanical mounting and/or hydraulic connection axis of the sensor, as observable hereinafter.
Indicated with 14 is a portion or wall of the body of the adaptor support 11 which is located at an end of the body itself, and in particular at the end opposite to the opening of the cavity 13, forming in the illustrated case a bottom of the cavity and a second face of the support body. Hereinafter, such wall 14 shall be referred to as �membrane portion� just for the sake of immediate comparison of the general geometry of the support body 11 with respect to the body of a monolithic sensor of the type described previously with reference to FIGS. 1 and 2.
It should be pointed out that, though the wall 14 of the support body 11 is herein referred to as �membrane portion�, it should not necessarily have a low thickness, similar or comparable to that of the membrane portions of the classic monolithic sensors, in order to be able to flex under the operative pressure of a fluid. In the case of the present invention, the thickness of the portion 14 which axially closes the cavity 13 of the adaptor support 11 may thus be definitely greater with respect to the membrane portion of the bodies of the known monolithic sensors, and thus even be non-deformable under the nominal or usual operation pressures of the sensor 10: as a matter of fact, in the sensor according to the invention, it is essentially the membrane 22 of the die 20 that should be able to be deformed under the action of the pressure of a fluid, with the aim of the respective detection or measurement. Furthermore, in embodiments alternative to that represented in FIGS. 4-8, the cavity 13 may be omitted or have a minimum height (for reference see the embodiments of FIGS. 22 and 23), with the body of the support 11 being entirely passed through by a hole.
Furthermore, in an embodiment of the invention associated to the three-dimensional body of the adaptor support 11 are specific electric contact means, so as to facilitate a sturdy and safe connection of the die 20 to the abovementioned circuit or terminal arrangement of a connector. A possible form of these contact means is illustrated in FIG. 9. Provided for on the face of the adaptor support 11 bearing the detection part 12 are connection contacts or tracks, made of electrically conductive material, for example copper, noble metals or metal alloys. These tracks, indicated with 28, have respective first ends 28 a that substantially end at sides of the detection part 12, and specifically of the substrate 25 (if present, like in the represented case). The connection of the first ends 28 a of the tracks 28 to the contacts 23 of the die 20 is preferably obtained through flexible contact elements, for example made of thin wires 29 made of electrically conductive material, preferably but not necessarily made of a noble metal, such as gold, welded or connected between the parts 23, 28 in question, according to per se known techniques (for example using processes of the known type such as �bonding�, preferably adding a protection insulating material, such as resin poured over the die and the bonding region).
In the illustrated example, the second ends of the tracks 28, indicated with 28 b, are substantially configured as pads, and form the physical interface for the actual electrical connection of the sensor 10 with the abovementioned circuit arrangement or the connector of a pressure sensor device. Obviously, the layout of the tracks 28 and the shape of the respective ends 28 b may be different from the one illustrated, depending on the needs; for example, the pad ends 28 b may have a central through hole, coaxial to a respective blind hole made in the face of the support 11: in such solution, fitted or fixed in the mentioned holes of the support 11 are first ends of the terminals that axially rise from the body 11 (for example of the type similar to those indicated with 5 a in FIG. 1), in such a manner to be at contact�also through possible welding�with the perforated pads 28 b of the tracks 28. In a solution, the abovementioned holes are configured as through holes and with a metallised surface, in order to bear the electrical connections on the face of the support 11 opposite to that on which the detection part 12 is provided for; thus in this case, conductive tracks may also be provided for on said opposite face of the support 11.
A MID technology useable for such purpose is that of plating known as �two-shot moulding�. In such case, for example, the body of the support 11 is formed initially through moulding of a first plateable plastic material. The body thus obtained is then selectively overmoulded with a second non-plateable plastic material, at the face of the membrane portion 14 outside the cavity 13, in such a manner to leave some regions of the first plateable material exposed, such exposed regions having a profile corresponding to that of the tracks or contacts 28 to be obtained; the tracks 28 are then actually formed through plating, right at the abovementioned exposed regions, using suitable conductive metal material, for example copper.
Another useable MID technology is the one referred to as �hot stamping�. In this case thin metal strips intended to form the tracks or contacts 28�for example obtained by blanking from a strip�are arranged in a heated mould, into which the material intended to form the body of the support is then introduced; obviously the arrangement of the abovementioned sheets or strips into the mould is such that, after the moulding of the plastic material, respective connection portions of the tracks 28 remain exposed with respect to the body of the adaptor support 11.
The body 102 a has a support portion 104 and a connection portion 105. As observable particularly in FIGS. 12 and 16, the portion 104 includes an internal wall 104 a that delimits a cavity or chamber 106 open at the opposite end with respect to the connection portion 105. Rising from the bottom of the chamber 106�in central position�is a tubular part 107, formed externally thereon being a step or a seat 107 a for positioning radial seal means, such as an o-ring gasket, observable only in FIG. 12, indicated with 108. Furthermore, the portion 104 of the body 2 a has an external or peripheral wall 109, that surrounds the wall 104 a and defines a perimeter seat therewith, indicated with 112 in FIG. 16. The portion 105 of the body 102 a is essentially configured as a hydraulic connection, mounted on which is a seal means, represented for example by an o-ring 113. The portion 105, which forms an inlet or pressure port of the device 101, is intended to be connected to a hydraulic circuit, not represented, containing the fluid to be subjected to pressure and temperature detection. In the illustrated example the portion 105 is passed through in axial direction by a conduit, indicated with 114 in FIG. 12, whose upper section passes through in the tubular part 107 which rises from the bottom of the chamber 106, forming an inlet passage of the device 101.
In FIGS. 12-16 indicated in its entirety with 135 is a positioning and/or support member, preferably made of plastic material, preferably thermoplastic, or metal material. With particular reference to FIG. 16, the member 135, hereinafter referred to as �spacer� for the sake of simplification, has appendages or pins, indicated with 136, intended to be coupled with the perimeter seats 16 of the adaptor support 11 of the sensor 10, with the aim of obtaining a polarisation, i.e. an accurate mutual coupling between the parts in question. In the example, the pins 136 have a substantially circular section, but their shape may obviously be different from the one represented, however preferably a shape at least partially complementary to that of the seats 16 of the support 11 of the sensor 10. Preferably, the wall 104 a of the body 102 a also has seats�indicated with 104 c in FIGS. 15 and 16�for accommodating at least one portion of pins 136. The spacer 135 has a central passage 138, having a section preferably smaller with respect to the area of the face of the support 11 on which the detection part 12 is located. The spacer 135 also defines a seat 139, preferably recessed, for positioning and/or accommodating�at least partially�the terminal board 131 of the circuit 130.
The body 103 a preferably has, inside the chamber 120, one or more axial projections (not represented) for peripherally pressing the spacer 135 against the body 102 a, thus maintaining it in position. Alternatively, the spacer 135 may be fixed (for example by means of screws) or welded to the body 102 a. Under normal conditions of use, the device 1 is hydraulically connected to a line of the fluid subjected to control, through the connection portion 105 fitted, for example, into a pipe of the fluid in question. The pressure of the fluid may exert pressure on the membrane 22 (FIG. 8) of the detection part 12 of the sensor 10, due to the presence of the detection passage represented by the hole 15 (FIGS. 5-6 and 8); in this manner a flexure of the abovementioned membrane 22 is caused, the degree of such flexure being detected through the circuit means integrated in the silicon die of the sensor: a signal representing the pressure value of the fluid is generated to the contacts 23 (FIG. 9) of the detection part 12. It should be observed that, under normal operation, the pressure of the fluid tends to push the adaptor support 11 of the sensor 10 in the direction opposite to the pressure inlet: though the support 11 is not rigidly connected to the casing, it cannot move in the abovementioned direction, due to the presence of suitable means, such as the spacer 135, which as mentioned is mounted between the bodies 102 a-103 a in fixed position. The signals representing the pressure, possibly amplified and/or treated and/or processed in a per se known manner by electronic components integrated in the die and/or provided for on the circuit 130, reach the terminals 126 of the device 1, which are electrically coupled to an external wiring�not represented�connected to a suitable external control unit.
In the illustrated example the sensor 10 is not rigidly coupled or fixed to the casing or to other internal parts of the device 101, and this characteristic contributes to reduce measurement errors, increasing the measurement accuracy and stability over time and/or avoiding risks of damage due to mechanical strains or stresses. Furthermore, as observed, according to a further preferential characteristic, also the circuit 130 is not rigidly coupled or fixed to the casing 102 a-103 a of the device. In the embodiment described, the sensor 10 is elastically associated to the abovementioned casing through the seal means represented by the gasket 108 of FIG. 12, interposed between the body of the support 11 of the sensor 10 and the body 102 a; on the opposite side, the spacer 135 is provided for between the support 11 of the sensor 10 and the part 103 a. The circuit 130 is instead borne on the spacer 135, i.e. i t is associated to a distinct component with respect to the casing or structure 102 a-103 a. Furthermore, the circuit 130, may not be mechanically fixed to the spacer 135: in such embodiment, the circuit 130 is mounted elastically with respect to the casing 102 a-103 a through the flexible contacts 127, interposed between the circuit itself and the body 103 a (in particular between the circuit and the terminals 126 integrated in the body 103 a); on the opposite side, the spacer 135 is provided for�in fixed position�between the circuit 130 and the body 102 a. The presence of the gasket 108 allows insulating the sensor 10 from the casing, and in such manner, any mechanical stresses applied on the casing are not transmitted to the sensor; also the preferred presence of the spacer 135 and/or of the flexible contact elements 127 and/or 132 contributes to make the assembly operations of the device 101 less critical, and thus simpler, and reduce or eliminate the risk that external strains or stresses operating on the body 102 a and/or 103 a be transmitted to the circuit 130; for such purpose, the presence of a slight mounting clearance or tolerance between the terminal board of the circuit 130 and the respective seat 139 defined in the spacer 135 is advantageous.
Illustrated in FIG. 17 is the case of a sensor 10 according to the invention whose support 11 defines�at the upper part�an accommodation 11 a, such as a recess or seat, for the positioning of a substrate 25 having plan overall dimensions definitely greater with respect to that of FIG. 8 (i.e. projecting laterally with respect to the die 20), without prejudice to the other characteristics described previously.
FIG. 19 illustrates a further variant, based on the use of materials and processes analogous to the ones mentioned with reference to the variant of FIG. 18. Also in this solution the tracks 28 are co-moulded, in such a manner to be partially emerged on the surface of the support 11; contrary to the previous case, the end section of the tracks 28 is folded upwards, with a portion however submerged in the material forming the support 11: in this solution, the �vertical� ends 28 b of the tracks 28 form terminals useable for connection towards a printed circuit board or PCB, which might be arranged over the sensor 10.
In the embodiments of FIGS. 18 and 19 the upper part of the support 11 is configured in a different manner with respect to the embodiments described previously, in such a manner to define also an annular edge or wall 14 a, that circumscribes the positioning region of the detection part of the sensor (or the part previously indicated with 12, including the die 20) and the main portion of the tracks 28. The support 11 of FIGS. 18 and 19 may for example be used alongside a spacer different from the one indicated with 135 in FIGS. 10-16, provided with means, for example in form of semicircular peripheral seats, suitable to be coupled with the projections indicated with 16 a, defined in the internal part of the wall 14 a. In the embodiments of FIGS. 18 and 19 the wall 14 a defines, alongside the wall 14, a chamber or blind cavity, advantageously deposited or poured in which may be a protection material, not represented, adapted to cover the detection part; this protection material, for example gel, is of the type resistant against chemical attack (for example a fluoride silica gel), but still allowing the deformation/flexure of the membrane 22 of the die 20 (FIG. 8).
The cavity 13 a of the body part 11 a is closed at the lower part by another part of the body of the adaptor support 11. In particular, indicated with 11 b is a substantially two-dimensional body part, configured as a thin membrane, added�at the lower part�to the body part 11 a, in such a manner to sealingly close the cavity 13 a; the membrane part 11 a is for example glued to the region of the lower face of the part 11 a that surrounds the opening of the cavity 13 a. The detection part 12 of the sensor, here without the substrate 25, is mounted on the body part 11 a opposite the cavity 13, substantially at the respective end of the hole 15 a. In such configuration, a flexure and/or deformation of the membrane 11 b, due to the pressure of the fluid subject to control, determines a pressure variation in the chamber formed by the cavity 13 a, the hole 15 a and the hole 21 of the die 20 (see FIG. 22), which is thus transmitted to the membrane 22 of the die, for detection purposes. The contacts 23 are provided for on the upper face of the die 20.
In a preferential version, the chamber formed by the cavity 13 a, the hole 15 a and the cavity 21 of the die 20 is filled in a known manner with an uncompressible fluid, such as a liquid not aggressive against the die 20, susceptible to transmit the deformations of the membrane part 11 b of the support 11 to the membrane 22 of the die. It is observable that the membrane part 11 b has a deformable region having an area definitely greater with respect to the membrane 22 of the die 20, and this allows �amplifying� the deformation effect of the membrane 11 a, due to the pressure of the fluid subjected to detection, towards the membrane 22.
It shall be observed that, with the embodiment of FIG. 22, the semiconductor sensor according to the invention is advantageously useable for the detection of fluids being potentially aggressive against the die 20 from a chemical or thermal point of view, without however requiring�as is typical in the prior art�having to provide for complex seal systems inside the detection device, to insulate a semiconductor sensor or a printed circuit board on which said sensor is mounted against the fluid. As a matter of fact, in the case of the solution of FIG. 22, use of material resistant against attack of the fluid subject of detection for making the membrane part 11 b is sufficient. It shall also be observed that the parts previously indicated with 11 a and 11 b may be possibly configured in a single piece, to form the support 11. Obviously also the device of FIGS. 9-16 overcomes the need of complex seal systems to insulate the printed circuit board from the fluid.
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