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 sensitive element and a lead frame contained within an overmoulded device package. The device package comprises an interfacing region carrying an access aperture on the underside of the device package providing fluid communication access to the pressure sensitive element and for coupling the pressure sensor device to a pressure port of a pressure sensing module into which the pressure sensor device is to be installed.

Typically, the pressure sensor module comprises an electrical circuit to which the pressure sensor device is surface-mount soldered. As well as soldering the pressure sensor device to the electronic circuit, it is necessary to sealingly connect the access aperture of the pressure sensor device to the pressure port of the pressure sensor module. In a mass-production environment requiring cost-effectiveness, it is challenging to solder the leads of the pressure sensor device to the electronic circuit of the pressure sensor module while also hermetically sealing the connection between the access aperture and the pressure port.

<CIT> exemplifies such an arrangement where a surface-mount pressure sensor device is soldered to a circuit carrier integrated with a pressure sensor module and to which the sensor device is also adhered. The construction disclosed in <CIT> is complex, rendering it difficult to manufacture and to ensure reliable manufacture quality without incurring excessive expense. In this regard, the thermal steps of the manufacturing process require a combination of adhesive curing to form the hermetic seal and reflow soldering. Additionally, it is necessary to apply the adhesive for curing and solder paste to the circuit carrier, and applying both the adhesive and the solder paste together is practically challenging from a manufacturing perspective. Furthermore, the circuit carrier has to be suitable for exposure to a medium being measured and this too results in constraints being placed on the choice of material employed for the circuit carrier, which increases the cost of manufacture of the pressure sensor module. <CIT> disclosed an electronic control unit comprising a packaged pressure sensor disposed therein. <CIT> discloses a system comprising an unpackaged sense die disposed within a housing.

According to a first aspect of the present invention, there is provided a pressure sensor module apparatus in accordance with claim <NUM>.

The intermediate carrier may be fixedly coupled to the module portion (<NUM>).

A portion of the upstanding pressure port may extend through the access aperture of the intermediate carrier.

The module portion may comprise a base, and the upstanding pressure port may be elongate and extend away from the base and through the intermediate carrier.

The upstanding pressure port may be adhered to the opposing surface of the moulded device package surrounding the access port of the pressure sensor device.

The module portion and the intermediate carrier may be configured to cooperate so that the module portion receives the intermediate carrier therein and in a predetermined position within the module portion.

The intermediate carrier may comprise a first locator aperture and a second locator aperture.

The intermediate carrier may comprise a third locator aperture. The module portion may comprise a first counterpart locator protrusion and a second counterpart locator protrusion, respectively configured to be received by the first and second locator apertures. The module portion may comprise a third counterpart locator protrusion configured to be received by the third locator aperture.

The module portion may comprise a base portion and the upstanding pressure port may be configured as an island in the base portion.

The module portion may comprise a base portion and the upstanding pressure port may have an abutting surface distal from the base portion; the upstanding pressure port may be configured to carry a peripheral lip at the distal end thereof.

The upstanding pressure port may comprise a central conduit defined by a tubular wall; the peripheral lip may be disposed at an internal edge of the tubular wall.

The upstanding pressure port may comprise a central conduit defined by a tubular wall; the peripheral lip may be disposed at an external edge of the tubular wall.

The upstanding pressure port may comprise a central conduit defined by a tubular wall; the peripheral lip may be disposed at an internal edge of the tubular wall and another peripheral lip may be disposed at an external edge of the tubular wall, thereby defining a recessed channel in the abutting surface.

The module portion may comprise a base portion and the upstanding pressure port may have an abutting surface distal from the base portion; and the abutting surface may be configured to provide augmented wettability as compared with the abutting surface being untreated.

According to a second aspect of the present invention, there is provided a pressure sensing module comprising: the pressure sensor module apparatus as set for the above in relation to the first aspect of the invention; and a pressure sensor module housing comprising the module portion.

The module portion may comprise a tubular protrusion defining the upstanding pressure port; the tubular protrusion may extend towards the access port; the tubular protrusion may comprise an abutting surface at a distal end of the tubular protrusion; and a layer of bonding compound may be disposed between the abutting surface and the moulded device package.

The tubular protrusion may extend towards the access port through the access aperture of the intermediate carrier.

According to a third aspect of the present invention, there is provided a method of manufacturing a pressure sensor module apparatus in accordance with claim <NUM>.

It is thus possible to provide an apparatus and method that facilitates simpler manufacture of the apparatus. In this regard, the application of adhesive and solder paste does not have to be done so as to accommodate contemporaneous curing of adhesive and reflow soldering. Additionally, the production yield is improved owing to a lesser degree of accuracy being required since the adhesive and solder paste deposition steps are decoupled.

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 portion <NUM> of a pressure sensor module <NUM>, constituting an interfacing substrate <NUM>, is operably coupled to a pressure sensor device <NUM>. The pressure sensor device <NUM> forms part of the pressure sensor module <NUM>. The interfacing substrate <NUM> comprises a peripheral side wall <NUM> integrally formed with a base portion <NUM> and a port formation <NUM>, for example an upstanding pressure port, extending away from the base portion <NUM>. In this example, the port formation <NUM> is generally centrally located relative to the peripheral side wall <NUM>. The peripheral side wall <NUM>, the base portion <NUM> and the port formation <NUM> cooperate to provide a recess <NUM> for receiving an intermediate carrier <NUM> comprising an access aperture <NUM> therethrough so that the intermediate carrier <NUM> is adjacent the interfacing substrate <NUM>, in particular the base portion <NUM>. As such, the port formation <NUM> extends away from the base portion <NUM> and through the access aperture <NUM> of the intermediate carrier <NUM>.

As described above, the pressure sensor module <NUM> is only described in part, and the skilled person should appreciate that the interfacing substrate <NUM> is described in isolation for the sake of clarity and conciseness description. In this regard, the pressure sensor module <NUM> can comprise a housing of any shape suited to an intended application, the housing comprising the interfacing substrate <NUM>.

The pressure sensor device <NUM> comprises a pressure sensitive element <NUM>, for example of the type disclosed in European patent publication no. <CIT>, disposed within a moulded device package <NUM>. Although not shown, connecting leads <NUM> extend through the moulded device package <NUM> to protrude therefrom at one end thereof and, at another end thereof, are coupled to the pressure sensitive element <NUM>, optionally via an integrated circuit (not shown) disposed within the moulded device package <NUM>.

The port formation <NUM> of the interfacing substrate <NUM> comprises an outwardly facing surface <NUM> at a distal end thereof, serving as an adhesion site and/or an abutting surface. The outwardly facing surface <NUM> in combination with the port formation <NUM> also constitutes an adhesion island within the base portion <NUM>.

The intermediate carrier <NUM> comprises electrical contact pads (not shown in <FIG>) disposed along opposite sides of the aperture <NUM> close to the aperture <NUM> and spaced so as to be in registry with a spacing between the connecting leads <NUM> of the pressure sensor device <NUM>. The connecting leads <NUM> of the pressure sensor device <NUM> are connected to the corresponding electrical contact pads of the intermediate carrier <NUM> by respective solder joints <NUM>.

The intermediate carrier <NUM> serves as, for example, a circuit board comprising one or more electrical circuit interconnects, and can comprise an electrical circuit (not shown) operably coupled to the electrical contact pads; the one or more electrical circuit interconnects can comprise the electrical contact pads, respectively. In this example, the intermediate carrier <NUM> is a Printed Circuit Board (PCB). In some examples, the intermediate carrier <NUM> comprise one or more circuit component coupled thereto. The intermediate carrier <NUM> is retained within the recess <NUM> in a predetermined position by locator protrusions <NUM> extending away from the base portion <NUM>, which pass through corresponding locator apertures <NUM> provided in the intermediate carrier <NUM>. The intermediate carrier <NUM> is fixed in place by rivet heads <NUM> formed on the tops of the locator protrusions <NUM>, thereby preventing removal of the intermediate carrier <NUM> from the locator protrusions <NUM>.

The port formation <NUM> comprises a substantially tubular wall and provides a conduit <NUM>, for example a central conduit, therethrough which is in fluid communication at a first end thereof with a chamber <NUM> defined by the moulded device package <NUM>, the pressure sensitive element <NUM> being located within the chamber <NUM>. An opening to the chamber <NUM> serves as an access port. A second end of the conduit <NUM> is in fluid communication with at least part of the remainder of the pressure sensor module <NUM> (not shown). An adhesive layer <NUM> disposed on the outwardly facing surface <NUM> contacts an opposing surface <NUM> of the moulded device package <NUM>, peripheral to the opening of the chamber <NUM> and serving as an interfacing surface, and sealingly coupled, for example by adhesion, the moulded device package <NUM> to the port formation <NUM>.

Turning to <FIG>, and also referring to <FIG>, solder paste <NUM> is applied (Step <NUM>) to the electrical contact pads <NUM> of the intermediate carrier <NUM> and the pressure sensor device <NUM> is arranged (Step <NUM>) on the intermediate carrier <NUM>, which is in an unpopulated state, so that free ends of the connecting leads <NUM> contact the solder paste <NUM>. Following placement of the pressure sensor device <NUM> on the intermediate carrier <NUM>, the intermediate carrier <NUM> and the pressure sensor device <NUM> undergo a solder reflow process (Step <NUM>) so that the connecting leads of the pressure sensor device <NUM> are reflow soldered to the electrical contact pads <NUM> of the intermediate carrier <NUM>, resulting in the formation of the solder joints <NUM> (<FIG>).

Referring to <FIG>, the interfacing substrate <NUM> is then optionally subjected (Step <NUM>) to plasma activation using any suitable known process, particularly but not exclusively to improve wettability of the outwardly facing surface <NUM> as compared with the outwardly facing surface <NUM> being untreated. Turning to <FIG>, the adhesive layer <NUM> is then applied (Step <NUM>) to the outwardly facing surface <NUM> of the interfacing substrate <NUM> and then the interfacing surface <NUM> of the moulded device package <NUM> is optionally also subjected (Step <NUM>) to plasma activation using any suitable known process, to improve wettability of the interfacing surface <NUM> as compared with the interfacing surface being untreated. In this example, the adhesive layer <NUM> is a heat curable adhesive, although the skilled person should appreciate that any other suitable kind of adhesive can be employed, for example an adhesive pre-cured by ultraviolet light prior to contact adhesion.

The intermediate carrier <NUM> is then inserted (Step <NUM>) into the recess <NUM> of the interfacing substrate <NUM>, the locator apertures <NUM> being aligned with the locator protrusions <NUM> so that the locator protrusions <NUM> extend through the locator apertures <NUM> when the intermediate carrier <NUM> is inserted into the recess <NUM> (<FIG>), thereby aligning the open end of the chamber <NUM> with the conduit <NUM> (<FIG>). In this state, the intermediate carrier <NUM> is temporarily aligned in the recess <NUM>. The rivet heads <NUM> are then formed at the exposed ends of the locator protrusions <NUM> to affix (Step <NUM>) the intermediate carrier <NUM> temporarily in the recess <NUM>. Thereafter, the adhesive layer <NUM> is cured (Step <NUM>) using any suitable known curing process and then the interfacing substrate <NUM>, with the intermediate carrier <NUM> and the pressure sensor device <NUM> are optionally overmoulded (Step <NUM>).

The skilled person should appreciate that the above-described implementations are merely examples of the various implementations that are conceivable within the scope of the appended claims. Indeed, it should be appreciated that although, in the above-described example, the outwardly facing, interfacing, surface <NUM> of the port formation <NUM> is flat, in other examples the outwardly facing surface <NUM> of the port formation <NUM> can comprise one or more peripheral boundary formations, for example peripheral lips. Referring to <FIG>, in one example an inner edge <NUM> of the outwardly facing surface <NUM> relative to the internal surface <NUM> of the port formation <NUM> comprises a first inner peripheral lip <NUM>. In this example, the first inner peripheral lip <NUM> slopes towards the base portion <NUM> so that the outwardly facing surface <NUM> comprises a flat or level surface portion <NUM> that meets the first inner peripheral lip <NUM>. A perpendicular height <NUM> of a highest point <NUM> of the first peripheral lip <NUM> with respect to the flat portion <NUM> of the outwardly facing surface <NUM> is equal to, or slightly greater than, an intended thickness <NUM> of the adhesive layer <NUM>. In another example (<FIG>), the outwardly facing surface <NUM> can comprise a second, outer, peripheral lip <NUM> at an outer edge <NUM> of the port formation <NUM>, the second peripheral lip <NUM> being provided instead of the first peripheral lip <NUM>. The highest point of the second peripheral lip <NUM> is at the outer edge <NUM> of the port formation <NUM>, and the second peripheral lip <NUM> slopes in a like manner to the first peripheral lip <NUM> described above. Similarly, the perpendicular height <NUM> of the second peripheral lip <NUM> with respect to the flat surface portion <NUM> of the outwardly facing surface <NUM> is defined in the same way as the first peripheral lip <NUM>. In a further example (<FIG>), the outer peripheral surface <NUM> can comprise both the first and second peripheral lips <NUM>, <NUM>, thereby forming a recessed channel <NUM> in the outwardly facing surface <NUM>.

Claim 1:
A pressure sensor module apparatus (<NUM>) comprising:
a pressure sensor device (<NUM>) comprising:
a pressure sensitive element (<NUM>) contained within a moulded device package (<NUM>);
connecting leads (<NUM>) operably coupled to the pressure sensitive element (<NUM>) and protruding through the moulded device package (<NUM>) for electrical connection thereto; and
an access port formed in the moulded device package (<NUM>) and configured to provide fluid communication with the pressure sensitive element (<NUM>);
an intermediate carrier (<NUM>) comprising an electrical circuit interconnect and an access aperture (<NUM>) therethrough, the intermediate carrier (<NUM>) comprising electrical contacts (<NUM>);
a module portion (<NUM>), the intermediate carrier (<NUM>) being disposed adjacent the module portion (<NUM>); and
the connecting leads (<NUM>) are respectively soldered to the electrical contacts (<NUM>) of the electrical circuit interconnect; the apparatus further comprising:
the access aperture (<NUM>) facing the access port formed in the moulded device package (<NUM>);
the module portion (<NUM>) comprising an upstanding pressure port (<NUM>);
the upstanding pressure port (<NUM>) being sealingly coupled to an opposing surface (<NUM>) of the moulded device package (<NUM>) surrounding the access port of the pressure sensor device (<NUM>); and
the upstanding pressure port (<NUM>) extending through the access aperture (<NUM>) of the intermediate carrier (<NUM>).