Patent Description:
In the field of pressure sensors, it is known to provide a packaged pressure sensor device. The pressure sensor device typically comprises a pressure sensing element and a lead frame contained within an overmoulded device package. The device package comprises an interfacing region carrying a circumferential wall on an externally facing surface for abutment with a port of pressure sensing module into which the pressure sensor device is to be installed.

In addition to the port mentioned above, the pressure sensing module comprises a lead frame and an optional lid, the lead frame of the pressure sensor device being electrically connected to the lead frame of the pressure sensing module. Optionally, although typically used, a potting compound is disposed within a housing of the pressure sensing module over the electrically connected lead frames of the pressure sensor device and the pressure sensing module. However, the potting compound can spill over a rear side of the interfacing region into the port of the pressure sensing module. Furthermore, the pressure sensor device, when a Printed Circuit Board (PCB)-less device, does not support the direct measurement of differential pressure while being sufficiently flexible for measurement of absolute or relative gauge pressure.

<CIT> discloses a pressure sensor device carrying a circumferential wall or ridge as described above. However, whilst the circumferential wall provides an adequate seal with a pressure port of a pressure sensing module for some applications, the seal can be further improved. <CIT> discloses a generally conically-shaped housing for a pressure sensor structure contained within an internal cavity capped by a corrugated lid. <CIT> discloses a partially overmoulded lead frame, the overmoulding structure providing a cavity to contain an integrated circuit, the cavity being closed by a lid. <CIT> discloses a housing body defining a pressure detection room containing a protective gel disposed over a pressure sensor structure. The housing body comprises a groove to capture excess protective gel introduced into the pressure detection room prior to closing the pressure detection room with a cap.

According to a first aspect of the present invention, as defined in claim <NUM>, there is provided a pressure sensor module comprising a body portion, the body portion comprising a pressure port and an annular recess surrounding an opening of the pressure port; and a pressure sensor apparatus disposed within the housing; wherein the pressure sensor apparatus comprises: a pressure sensitive structure; a device package comprising a profiled interface region, the profiled interface region comprising a front side and a back side; and a lead frame encapsulated at least in part by the device package and operably coupled to the pressure sensitive structure; wherein the front side is configured to abut sealingly, when in use, against an opposing surface to dock directly with the pressure port; the back side comprises a first surrounding ridge structure and a second surrounding ridge structure; the profiled interface region comprises an aperture for providing access to the pressure port; and the front side of the profiled region comprises a third surrounding ridge structure adhered at least in part in the annular recess by an adhesive to secure the pressure sensor apparatus to the pressure port and to mate sealingly the front side of the profiled interface region against the pressure port.

The first surrounding ridge structure may be formed from the same material as the device package.

The second surrounding ridge structure may be formed from the same material as the device package.

The first and/or second surrounding ridge structure may be integrally formed with the device package.

The first surrounding ridge structure may be configured as a first loop. The second surrounding ridge structure may be configured as a second loop.

The first surrounding ridge structure may be circular. The second surrounding ridge structure may be circular.

The first surrounding ridge structure and the second surrounding ridge structure may be concentric.

The first surrounding ridge structure may encircle the aperture.

The profiled interface region may comprise a base surface; the first surrounding ridge structure and the second surrounding ridge structure may extend away from the base surface, and the first surrounding ridge structure may extend further than the second surrounding ridge structure.

The profiled interface region may be an overmoulded profile interface region.

The pressure sensitive structure may comprise a deformable membrane in fluid communication with the aperture.

The apparatus may further comprise: a pressure communication conduit having a first end operably coupled to the back side of the profiled interface region for providing fluid communication with another pressure port of the pressure sensor module.

The pressure sensitive structure may be off-axis with respect to the device package.

The body portion may comprise a channel surrounding the pressure port; the third surrounding ridge structure may be adhered at least in part within the channel.

The housing may further comprise a lid portion. The lid portion may comprise a pressure communication region.

The pressure communication region may be a port. The port may be protected by a membrane.

The body portion may further comprise another pressure port.

The another pressure port may be in fluid communication with the back side of the profiled interface region.

The another pressure port may be surrounded by another channel; a second end of the pressure communication conduit may be adhered at least in part in the another channel.

The module may further comprise: a baffle wall between the pressure port and the another pressure port.

The baffle wall may be configured to impede the potting compound from entering the another pressure port.

The module may further comprise a potting compound disposed in the body portion and surrounding the second ridge structure without contacting the first ridge structure.

The housing may further comprise the lid portion and the pressure communication conduit may be integrally formed with the lid portion of the housing.

The module may further comprise another pressure sensor apparatus disposed therein; the another pressure sensor apparatus may comprise: another pressure sensitive structure; another lead frame operably coupled to the another pressure sensitive structure; and another device package comprising another profiled interface region, the another profiled interface region comprising another front side and another back side; wherein the another front side may be configured to abut sealingly, when in use, against another opposing surface of the body portion, thereby directly docking with the another pressure port; and the another profiled interface region may comprise another aperture for providing access to the another pressure port.

The another back side may comprise another first surrounding ridge structure and another second surrounding ridge structure.

It is thus possible to provide an apparatus that is relatively simple to manufacture whilst providing an improved seal with a pressure port of a pressure sensing module. In this regard, the seal is capable of efficiently seal against leakage of harsh fluids that can be corrosive, for example halogens, such as Iodine, urea, ammonia and so-called AdBlue. Furthermore, the provision of first and second surrounding ridge structures improves resilience from potting or coating compound reaching the pressure sensing structure and thereby hindering performance of the pressure sensing structure. The provision of adhesive further improves the seal in some embodiments, the adhesive being advantageously contained by the provision of the first and second surrounding ridge structures. The use of adhesive also permits the apparatus to be formed from a common material, thereby reducing manufacturing complexity and cost.

At least one embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:.

Throughout the following description, identical reference numerals will be used to identify like parts.

Referring to <FIG>, a pressure sensor apparatus <NUM> comprises a device package <NUM> formed by, for example, moulding, and leads <NUM> of a lead frame shown partially exposed as some of the lead frame is encapsulated in the moulding of the device package <NUM>.

The device package <NUM> comprises a pressure sensitive structure (not shown), and the lead frame is operably coupled to the pressure sensitive structure. In some examples, one or more passive electrical components (not shown) can be operably coupled to the lead frame beneath the moulding. Typically, the pressure sensitive structure can be, for example, a MEMS structure comprising a pressure sensitive membrane overlying a close cavity in a substrate. Electrical tracks are made to one or more devices, for example piezoresistors, formed on or around the membrane. The pressure sensitive structure can be configured for absolute or relative pressure sensing depending upon the application for which the pressure sensitive structure is required. In other examples, capacitive pressure sensing devices can be formed on or around the membrane. The electrical tracks are operably coupled to the leads frame, optionally through an intermediary interface circuit that can be integrated with the MEMS structure or can be independent of the MEMS structure.

The device package <NUM> also comprises a profiled interface region <NUM> (<FIG>) having a front side <NUM> and a back side <NUM>, the profile interface region <NUM> being overmoulded in this example. The front side <NUM> of the profiled interface region <NUM> is shaped, and hence configured, to abut against an opposing surface (not shown) for direct docking with a pressure port of a pressure sensor module, more details of which will be described later below.

The back side <NUM> of the profiled interface region <NUM> comprises a first surrounding ridge structure <NUM> and a second surrounding ridge structure <NUM>. The first surrounding ridge structure <NUM> is, in this example formed from the same material as the device package <NUM>. Similarly, the second surrounding ridge structure <NUM> is, in this example, formed from the same material as the device package <NUM>. In this example, the first surrounding ridge structure <NUM> and the second surrounding ridge structure <NUM> are integrally formed with the device package <NUM>.

The first surrounding ridge structure <NUM> is arranged as a first loop, for example a circular loop. Similarly, the second surrounding ridge structure <NUM> is arranged as a second loop, for example a circular loop. However, the skilled person should appreciate that other shaped loops can be employed.

Additionally, the first and second surrounding ridge structures <NUM>, <NUM> are concentric with respect to each other and substantially centred around an aperture <NUM> described later herein. In this regard, the first surrounding ridge structure <NUM> encircles the aperture <NUM>.

In some examples, the pressure sensitive structure can be off-axis with respect to a central axis of the device package <NUM>. In such examples, the first and second surrounding ridge structures <NUM>, <NUM> can still surround the aperture <NUM>, but are not concentric with the aperture <NUM>.

The device package <NUM> provides a base surface <NUM> for the profiled interface region <NUM>, and the first surrounding ridge structure <NUM> and the second surrounding ridge structure <NUM> respectively extend away from the base surface <NUM>. In this example, the first surrounding ridge structure <NUM> extends further than the second surrounding ridge structure <NUM>, i.e. the first surrounding ridge structure <NUM> extends further away from the base surface <NUM> than the second surrounding ridge structure <NUM>. Each of the ridges can have a height of between about <NUM> and <NUM>, for example about <NUM>. The first surrounding ridge structure <NUM> can be up to about three times taller than the second surrounding ridge structure <NUM>. In this example, the first and second surrounding ridges <NUM>, <NUM> have rounded extremities, but the distal surfaces of the first and second surrounding ridges <NUM>, <NUM> can be of any suitable profile.

The front side <NUM> comprises a third surrounding ridge <NUM>. The profiled interface region <NUM> also has the aperture <NUM> for providing access to the pressure port of the pressure sensor module (described later herein). In this example, the pressure sensitive structure comprises a deformable membrane <NUM> that closes the aperture <NUM>. A layer of gel <NUM> overlies the deformable membrane <NUM> from the front side <NUM>.

Turning to <FIG>, the pressure sensor module <NUM> mentioned above comprises the pressure sensor apparatus <NUM>. The pressure sensor module <NUM> comprises a housing <NUM> having a body portion <NUM> and a lid <NUM>, the body portion <NUM> defining an open chamber that is closed by the lid <NUM>. The body portion <NUM> of the housing <NUM> comprises a pressure port <NUM> disposed at a base <NUM> of the body portion <NUM>, the pressure sensor apparatus <NUM> overlying an opening of the pressure port <NUM>. As such, the pressure sensor apparatus <NUM> is disposed within the housing <NUM>. The front side <NUM> of the profiled interface region <NUM> is sealingly mated against the pressure port <NUM>.

In order to accommodate and receive the third surrounding ridge <NUM> of the device package <NUM>, the body portion <NUM> comprises an annular recess or channel <NUM> surrounding the opening of the pressure port <NUM>. The device package <NUM> and hence the pressure sensor apparatus <NUM> is secured to the pressure port <NUM> by way of the third surrounding ridge <NUM> extending, at least in part, into the annular channel <NUM> following deposition of an adhesive <NUM> into the annular channel <NUM> so that the third surrounding ridge structure <NUM> is adhered, at least in part, in the annular channel <NUM>. The leads <NUM> extend away from the device package <NUM> and overlie a module lead frame <NUM> and are operably coupled to the module lead frame <NUM>, for example by welds. In this example, the body portion <NUM> comprises an outwardly extending peripheral wall <NUM> extending away from a side wall <NUM> of the body portion <NUM> and defining a connector aperture <NUM>. The module lead frame <NUM> extends through the side wall <NUM> of the body portion <NUM> and into the connector aperture <NUM> for connection to external electronic circuitry. A potting or coating compound <NUM> surrounds the lead frame of the pressure sensor apparatus <NUM> and the module lead frame <NUM>. The potting compound <NUM> can be optionally provided.

The first and second surrounding ridges <NUM>, <NUM> serve to prevent ingress of the potting compound <NUM> into pressure port <NUM>. Indeed, once deposited, the potting compound <NUM> surrounds the second surrounding ridge <NUM> without contacting the first surrounding ridge <NUM>.

In this example, the lid <NUM> is attached to the body portion <NUM> by welding. However, the lid <NUM> can be attached to the body portion <NUM> using other techniques, for example the application of adhesive or mechanical clamping. In some examples, the attachment of the lid <NUM> to the body portion <NUM> can provide a hermetic seal.

The above pressure sensor module <NUM> measures absolute pressure. In this regard, the membrane <NUM> of the pressure sensor apparatus <NUM> is only responsive (directly or indirectly) to pressure at the front side <NUM> of the pressure sensor apparatus <NUM>. In another example, to measure relative pressure, the membrane <NUM> of the pressure sensor apparatus <NUM> is responsive (directly or indirectly) to pressure at both the front and back sides of the pressure sensor apparatus <NUM>. To support such relative pressure sensing, the lid <NUM> is provided with an ambient aperture or port <NUM> (<FIG>), constituting a pressure communication region, to allow the back side <NUM> of the pressure sensor apparatus <NUM> access to atmospheric pressure. In another example, the ambient aperture <NUM> can be provided in the body portion <NUM> instead of in the lid <NUM>. In another example, the ambient aperture <NUM> can be closed by a protective membrane (not shown) so as to create a barrier to, for example, moisture from entering the chamber of the housing <NUM>.

In another example (<FIG>), the pressure sensor module <NUM> is a differential pressure sensor and comprises a first pressure port <NUM> as in the previous examples, and a second pressure port <NUM>, the second pressure port <NUM> being spaced from the first pressure port <NUM>. In this regard, the first and second pressure ports <NUM>, <NUM> are at the base <NUM> of the body portion <NUM> and separated from each other by a partition or baffle wall <NUM> to impede the potting compound <NUM>, once deposited, from entering the second pressure port <NUM>. The pressure sensor apparatus <NUM> is a differential pressure sensor and overlies the first pressure port <NUM>. In order to provide differential pressure sensing, as in the embodiment of <FIG>, the membrane <NUM> of the pressure sensor apparatus <NUM> is responsive (directly or indirectly) to pressure at both the front and back sides of the pressure sensor apparatus <NUM>. The chamber of the housing <NUM> comprises a first internal region <NUM> and a second internal region <NUM>, the first internal region <NUM> being to a first side of the partition wall <NUM> and comprising the first pressure port <NUM>, and the second internal region <NUM> being to a second side of the partition wall <NUM> and comprising the second pressure port <NUM>.

As in the previous examples, the lid <NUM> is attached to the body portion <NUM> hermetically, a clearance <NUM> between the partition wall <NUM> and an underside of the lid <NUM> providing access between the first and second internal regions <NUM>, <NUM>. In this example, the lid <NUM> does not comprise the ambient aperture <NUM> of the previous example. The potting or coating compound <NUM> is contained within the first internal region <NUM> by virtue of the partition wall <NUM> and the remaining peripheral side wall, including the side wall <NUM>, of the body portion <NUM>.

By virtue of the clearance <NUM>, the first internal region <NUM> is in fluid communication with the second internal region <NUM> and thus the back side <NUM> of the pressure sensor apparatus <NUM> is in fluid communication with the second pressure port <NUM>.

Referring to <FIG>, in another example, another differential pressure sensor module structure comprises an internal conduit <NUM>, constituting a pressure communication conduit, that has an inverted substantial U-shape. In this example, a first end <NUM> of the internal conduit <NUM> is shaped to correspond to a first channel <NUM> between the first and second surrounding ridge structures <NUM>, <NUM>, which in this example is annular. The diameter of the first end <NUM> of the internal conduit <NUM> corresponds to the diameter of the first channel <NUM>. The first end <NUM> of the internal conduit <NUM> is thus circular and is adhered in place in the first channel <NUM> by an adhesive.

In this example, the partition wall <NUM> of the previous example surrounds the second pressure port <NUM> and comprises a second channel <NUM> formed in the upper end of the partition wall <NUM>. A second end <NUM> of the internal conduit <NUM> is shaped to correspond to the second channel <NUM>, which in this example is annular. The diameter of the second end <NUM> of the internal conduit <NUM> corresponds to the diameter of the second channel <NUM>. The second end <NUM> of the internal conduit <NUM> is thus circular and is adhered in place in the second channel <NUM> by an adhesive. The provision of the internal conduit <NUM> therefore obviates the need to seal hermetically the lid <NUM> to the body portion <NUM>. As in the previous example, the membrane <NUM> of the pressure sensor apparatus <NUM> is responsive (directly or indirectly) to pressure at both the front and back sides of the pressure sensor apparatus <NUM>.

Turning to <FIG>, instead of providing the internal conduit <NUM> as a separate piece part of the pressure sensor module <NUM>, in another example, the internal conduit <NUM> is integrally formed with the lid <NUM>, conduit side walls <NUM> extending from the lid <NUM> to form the internal conduit <NUM>, an underside surface <NUM> of the lid <NUM> forming part of a wall structure of the internal conduit <NUM>. In such an example, the first and second ends <NUM>, <NUM> of the internal conduit <NUM> respectively cooperate with and are adhered, at least in part, in the first and second channels <NUM>, <NUM> in the same manner as described above in relation to the example of <FIG>.

Referring to <FIG>, in another example, the second pressure port <NUM> is provided as in the example of <FIG>. However, the partition wall <NUM> is absent and, instead, the base <NUM> of the body portion <NUM> comprises an additional annular channel <NUM> that surrounds the second pressure port <NUM>. An additional pressure sensor apparatus <NUM> of the same kind as the pressure sensor apparatus <NUM> is also provided and overlies the second pressure port <NUM> so that the front side <NUM> of the additional pressure sensor apparatus <NUM> abuts an opening of the second pressure port <NUM>. In this example, the pressure sensor <NUM> and the additional pressure sensor apparatus <NUM> are absolute pressure sensors and so are only responsive (directly or indirectly) respectively to pressure at the front sides <NUM> of the pressure sensor apparatus <NUM> and the additional pressure sensor apparatus <NUM>.

The device package <NUM> of the additional pressure sensor apparatus <NUM> and hence the additional pressure sensor apparatus <NUM> is secured to the second pressure port <NUM> by way of the third surrounding ridge <NUM> of the additional pressure sensor apparatus <NUM> extending into the additional annular channel <NUM> following deposition of an adhesive <NUM> into the additional annular channel <NUM>. In this example, the leads <NUM> of the additional pressure sensor apparatus <NUM> requiring electrical connection extend away from the device package <NUM> in a direction opposite to corresponding leads <NUM> of the pressure sensor apparatus <NUM>. However, in other examples, the leads <NUM> can extend differently than described above. The leads <NUM> of the additional pressure sensor apparatus <NUM> requiring electrical connection overlie another portion of the module lead frame <NUM> internal to the pressure sensor module <NUM> and are operably coupled to the module lead frame <NUM>, for example by welds. The potting or coating compound <NUM> surrounds the lead frames <NUM> of the pressure sensor apparatus <NUM>, the additional pressure sensor apparatus <NUM> and the module lead frame <NUM>. The potting compound <NUM> can be optionally provided.

As in the previous examples, the first and second surrounding ridges <NUM>, <NUM> of the pressure sensor apparatus <NUM> of the additional pressure sensor apparatus <NUM> serve to prevent ingress of the potting compound <NUM> into the corresponding pressure ports <NUM> of the pressure sensor apparatus <NUM> and the additional pressure sensor apparatus <NUM>. Indeed, once deposited, the potting compound <NUM> surrounds the second surrounding ridge <NUM> without contacting substantially the first surrounding ridge <NUM>.

In this example, the lid <NUM> closes the open body portion <NUM> and is attached to the body portion <NUM> and optionally forms a hermetic seal in a like manner to the pressure sensor module of <FIG>, i.e. the lid <NUM> does not comprise an aperture. However, in other examples (<FIG>) the lid <NUM> can comprise an ambient aperture <NUM>, optionally closed by a protective membrane (not shown). In such examples, the pressure sensor apparatus <NUM> and the additional pressure sensor apparatus <NUM> are relative pressure sensor apparatus and so are respectively responsive (directly or indirectly) to pressure at both the front and back sides of the pressure sensor apparatus <NUM> and the additional pressure sensor apparatus <NUM>. However, the skilled person should appreciate that, in other examples, the additional pressure sensor apparatus <NUM> can be of a different kind to the pressure sensor apparatus <NUM>. In this regard, the pressure sensor module <NUM> can comprise only relative pressure sensors or a combination of relative and absolute pressure sensors.

Claim 1:
A pressure sensor module comprising:
a housing (<NUM>) comprising a body portion (<NUM>), the body portion (<NUM>) comprising a pressure port (<NUM>) and an annular recess (<NUM>) surrounding an opening of the pressure port (<NUM>); and
a pressure sensor apparatus (<NUM>) disposed within the housing (<NUM>); wherein the pressure sensor apparatus (<NUM>) comprises:
a pressure sensitive structure;
a device package (<NUM>) comprising a profiled interface region (<NUM>), the profiled interface region (<NUM>) comprising a front side (<NUM>) and a back side (<NUM>); and
a lead frame (<NUM>) encapsulated at least in part by the device package (<NUM>) and operably coupled to the pressure sensitive structure; wherein
the front side (<NUM>) sealingly abuts against an opposing surface to dock directly with the pressure port (<NUM>);
the back side (<NUM>) comprises a first surrounding ridge structure (<NUM>);
the profiled interface region (<NUM>) comprises an aperture (<NUM>) for providing access to the pressure port (<NUM>);
and
the front side (<NUM>) of the profiled interface region (<NUM>) comprises a third surrounding ridge structure (<NUM>) adhered at least in part in the annular recess (<NUM>) by an adhesive (<NUM>) to secure the pressure sensor apparatus (<NUM>) to the pressure port (<NUM>) and to mate sealingly the front side (<NUM>) of the profiled interface region (<NUM>) against the pressure port (<NUM>).
characterized in that the back side (<NUM>) further comprises a second surrounding ridge structure (<NUM>).