Integrated circuit package

Integrated circuit package including an integrated circuit, external connection elements (3) connected to the integrated circuit, a package material (2) enclosing the integrated circuit, and a mechanical element (5, 6, 7) allowing a mechanical connection of a further element to the integrated circuit package (1). The mechanical element (5, 6, 7) is e.g. an attachment element (5); a mechanical element (5), optionally with a thread; a bushing element; a bearing element (7); an electrical connector (6).

FIELD OF THE INVENTION

The present invention relates to an integrated circuit package comprising an integrated circuit, external connection elements connected to the integrated circuit, and a package material enclosing the integrated circuit.

PRIOR ART

Such an integrated circuit package is known from European patent publication EP-A-2 090 873 of applicant. In the embodiments shown here, the integrated circuit may comprise various components, such as a sensor assembly with a sensors/face, carrier element for holding the sensor assembly and further associated components, such as processing electronics (IC or ASIC).

American patent publication US2007/215999 discloses a semiconductor device wherein a resin package encloses an integrated circuit including terminals 90, 92, 96 extending perpendicular to a substrate surface. The terminals can be provided with an internal screw thread.

American patent publication US2013/215585 discloses a package for an integrated circuit having a through hole 3 therein. The through-hole 3 accommodates an electrical connection terminal 4, which can e.g. be contacted using an external pin contact 12.

European patent publication EP-A-2 216 814 discloses an integrated circuit where bushes 16 are provided on contact pads of an integrated circuit. The bushes 16 ensure openings are available in a package surrounding the IC, in which connecting terminals 14 may be provided as external electrical contacts.

SUMMARY OF THE INVENTION

The present invention seeks to provide an improved integrated circuit package, allowing more robust and reliable operation of the integrated circuit package, e.g. as a complete sensor package with a sensor, such as a pressure, temperature or position sensor.

According to the present invention, an integrated circuit package according to the preamble defined above is provided, the integrated circuit package further comprising a mechanical element allowing a mechanical connection of a further element to the integrated circuit package. The mechanical element can be of an open type (through hole) or a closed version type.

By adding such a mechanical element in an integrated circuit package, further functional capabilities, external connection implementations, and low-cost solutions can be provided for integrated circuit packages, especially for integrated circuit packages including a sensor. The external connection elements are e.g. bended leads, leads, pins, lead pads, solder balls, connection-holes, etc.

In an embodiment, the mechanical element is selected from the group consisting of an attachment element; a mechanical element with a (n internal) thread; a bushing element; a bearing element; an electrical connector. This allows various connections to be implemented with an integrated circuit package, ranging from mechanical to electrical connections.

The integrated circuit package may comprise a sensor element connected to the integrated circuit in a further embodiment, wherein the mechanical element is not providing an external communication channel to the sensor element. E.g. the external communication channel may be provided in a part of the integrated circuit package where it cannot interfere with the mechanical element of the present invention embodiments.

In a further embodiment, the mechanical element is attached to a structural element of the integrated circuit package, such as a lead frame, a support frame, a ceramic substrate or a multi chip module. This results in an improved strength of the total integrated circuit package, and allows a more easy assembly process for molding the package.

The mechanical element is suspended in the integrated circuit package in an even further group of embodiments. This may be implemented in an embodiment, wherein the package material is formed by a two step molding process. No functional relationship is then present between mechanical element and sensor element of other (structural) parts of the integrated circuit package.

In a further embodiment, the integrated circuit package further comprises a sensor element connected to the integrated circuit, and a communication channel to the sensor element is provided via the suspended mechanical element. This allows external connection of further elements, such as tubing, to allow external environmental elements, e.g. external air, to reach the sensor surface.

The mechanical element may be provided with an external interface surface in a further embodiment, and the integrated circuit package material is present (e.g. molded) around the remaining external surface of the mechanical element. This allows a good mechanical interface with further components outside the integrated circuit package, yet also allows proper protection of the covered parts of the mechanical element.

In an exemplary embodiment, the mechanical element is a bearing element, and the integrated circuit package further comprising a sensor inside the package, an external connection axis supported by the bearing element, and a sensor activation element attached to the external connection axis. The sensor may be a Hall or magneto-resistive sensor, and the sensor activation element is an active-type element (such as a magnet or magnetized element) or a passive-type element (whereby the magnetization is replaced by a tooth structure).

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIGS. 1 to 3each show an embodiment of an integrated circuit package according to the present invention. The package comprises an integrated circuit and external connection elements3connected to the integrated circuit inside the package (e.g. using bond wires or flip chip). The external connection elements3can be connected to an electrical circuit on e.g. a printed circuit board.

Package material2of the integrated circuit package1encloses the integrated circuit tightly, thereby providing protection. The integrated circuit package further comprises a mechanical element5,6,7allowing a mechanical connection of a further element to the integrated circuit package1. The further element is e.g. a cooling body at attachment element(s) for such a cooling body, an electrical connector (e.g. a (mini-) USB connector, a guiding element for alignment purposes, or an axis as part of a sensor assembly.

The surprising technical effect of the presence of the mechanical element5,6,7is that the integrated circuit package1can be mechanically mounted and/or centered and/or electrically connected to other parts or subassemblies. The mechanical element5,6,7provides robust mechanical fixation on next level assemblies and/or onto other elements such as cooling blocks. Further electrical connections can also be made through the mechanical element6, for example, the mechanical element6may provide an electrical connection to a power supply, further electronics, a computer etc. The mechanical element6in the form of an electrical connector can be implemented in many variants, such as the USB connector mentioned above, or e.g. a wire-connection (known in the field as e.g. ‘schneidklemmtechnik’).

In an embodiment, the mechanical element5,6,7is selected from the group consisting of an attachment element5; a mechanical element5with a thread; a bushing element; a bearing element7; an electrical connector6.

In typical embodiments, the package material2is a duroplast plastic material for providing solid anchoring and encapsulation of the mechanical element5,6,7.

In an embodiment, the attachment element5may be a snap fit connector for a rapid and easy connection. In a further embodiment, the mechanical element5may be a standardized bolt or nut, so that the mechanical element5may comprise an internal and/or external threaded part.

The integrated circuit package1can then be robustly mounted and attached to other subassemblies. This embodiment may also be advantageous in view of vibratory environments, where the external connection elements3and/or a delicate sensor inside the integrated circuit packages1cannot sustain long periods of harsh vibrations. A firm fixation though a mechanical element5having a threaded part may resolve this issue. In addition to the fixation/vibration solution the mechanical element5can function as a cooling element as well. The heat generated by the integrated circuit element4e.g. a IGBT or MOSFET can be dissipated to the ambient via the mechanical element5acting as a heat sink.

In further embodiments, centering the integrated circuit package1with respect to other parts or subassemblies is readily accomplished by a mechanical bushing element5, e.g. a guide bushing. Such a bushing element5provides high precision centering of the integrated circuit package1but may allow for some rotational and linear sliding movement with respect to a connecting element disposed in the bushing element5.

For example, the integrated circuit package1may comprise a position sensor and should be able to move with respect to e.g. a connecting element slidably disposed inside the bushing element. Further, the integrated circuit package1may be subjected to temperature and/or pressure changes, so that allowing for some sliding movement of the mechanical bushing element5with respect to a connecting element disposed therein may minimize stress and strain forces inside the integrated circuit package1as a result of such temperature and/or pressure changes.

In certain situations the integrated circuit package1is intended to be connected to various different external devices. In an embodiment, the mechanical element6may comprise an electrical connector for utilizing standard communication protocols for an external device, e.g. USB, FireWire, HDMI etc. Embedding such an electrical connector6in the integrated circuit package1avoids additional external connecting element3, thereby simplifying e.g. a printed circuit board (PCB) onto which the integrated circuit package1may be mounted. The mechanical element6in the form of an electrical connector6may thus provide supplemental functionality that need not be implemented into a PCB onto which the integrated circuit package1is mounted.

In further embodiments, the mechanical element7may be a mechanical bearing element7allowing a shaft or axis to be rotatably mounted in the integrated circuit package1. Such a mechanical bearing element7may be particular advantageous in case the package1comprises e.g. a position sensor, e.g. a rotational (Magneto Resistive) MR sensor type, wherein rotating a connecting element inside the bearing7with respect to the integrated circuit package1measures a rotation of said package1with respect to the connecting element inside the bearing7.

The type of mechanical element5,6,7used may be determined by a particular application of the integrated circuit package1. For example, in case the package1comprises a temperature or pressure sensor, fixation through a mechanical threaded element5may be desired. Should the integrated circuit package1comprise a mechanical motion sensor, embedding a mechanical bearing element7is advantageously used.

It is also possible that the mechanical element5,6,7is chosen based on an assembly process. For example, having a mechanical bushing element5embedded in the integrated circuit package1may facilitate the use of pick-and-place robots for handling the integrated circuit package1. In such an application a robot may slidably insert a pin element inside the bushing5and slidably rotate/orientate the integrated circuit package1with respect to e.g. a PCB.

In the embodiments ofFIGS. 1 to 3, the integrated circuit package1may further comprise an external communication channel through the package material2for exposing a sensing surface of a sensor element inside the package1to the outside environment, thereby facilitating e.g. temperature and/or pressure measurements. Such an external communication channel is conveniently provided by an embedded (hollow) mechanical element5in the package material2, such as a nut and/or or guide bushing which typically comprise a bore running there through. The bore of the mechanical element5then comprises at least in part the external communication channel.

In a further embodiment of an integrated circuit package1, the package1comprises a sensor element20connected to the integrated circuit, and the mechanical element5,6,7is not providing an external communication channel to the sensor element20. In this embodiment, the mechanical element5,6,7is embedded in the package material2away from the sensor element20, i.e. in no direct contact with the sensor die or sensor surface of the sensor element20. This may be possible when the sensor element20does not require a direct exposure to the outside environment through an external communication channel. This embodiment is particular suitable for a sensor element20utilizing field phenomena, such as a magnetic and/or electric field, which easily penetrate the package material2. In an alternative to this embodiment, the sensor element20is in communication with the external environment using an external communication channel routed away from the mechanical element5,6,7(e.g. via a back side of the package1).

According to a further invention embodiment, the mechanical element5,6,7is suspended in the integrated circuit package1. In this embodiment the mechanical element5,6,7, is in a suspended arrangement with respect to the package material2, on that the mechanical element is solely supported by package material2and does not come into contact with a structural element22, sensor element20, or the external connecting elements (e.g. lead frame)21in the integrated circuit package1. Suspending the mechanical element5,6,7solely in package material2reduces the risk of damaging internal parts the package1, such as sensitive and delicate sensing materials and/or various electronics. This embodiment may be accomplished using a two-stage process, as explained in greater detail with reference toFIG. 7below.

FIG. 4shows another embodiment of the integrated circuit package1of the present invention. In this embodiment, the mechanical element7has an external interface surface7aand the package material2is present (e.g. molded) around the remaining external surface of the mechanical element7. In this embodiment the interface surface7a(e.g. parallel to a main surface of the integrated circuit package1) remains free from package material2, so that said surface7amay abut against another surface part or subassembly. This embodiment is advantageous in case a snug and precise fit of the mechanical element5,6,7against another surface part is required, as might be the case when the mechanical element5,6,7, is implemented as a bearing element7.

In a further embodiment, the integrated circuit package1comprises a projection2aof package material2, wherein the mechanical element5,6,7is at least in part embedded in the projection2adistal to the integrated circuit package1. The projection allows for an offset of the mechanical element5,6,7, with respect to the integrated circuit package1.

FIGS. 5 and 6show embodiments of the integrated circuit package1of the present invention, wherein the mechanical element5,6,7is a bearing element7, and the integrated circuit package1further comprises a sensor element20inside the package1, an external connection axis15supported by the bearing element7, and a sensor activation element17attached to the external connection axis15. The external connection axis15is attached to an external housing16and configured for rotating the activation element17. The activation element can be an active-type (magnetized) or passive-type whereby the magnetization is replaced by a tooth structure. In further embodiments the external connection axis15is provided with a cog18for rotation thereof, allowing a mechanical connection to an external subassembly in a simple and reliable manner. The external connection axis15(and hence mechanical element7in the form of a bearing element) may penetrate entirely through the integrated circuit package1, or alternatively, may be present only on one side (closed version of the mechanical element) of the integrated circuit package1. The bearing element7may be embodied as a simple guiding bush.

In an embodiment, the sensor element20is a Hall or magneto-resistive (MR) sensor and the sensor activation element17is a magnet. Here the mechanical element7need not provide a direct external communication channel to the outside environment as the sensor element20senses a magnetic field change between north and south poles penetrating the package material2.

In the embodiment ofFIGS. 5 and 6, the mechanical element5,6,7is attached to a structural element22of the integrated circuit package1, such as a lead frame, a support frame, a (ceramic or PCB) substrate or a multi chip module. Having the mechanical element5,6,7, in direct contact with the structural element22may provide further strength to the embedded arrangement of the mechanical element5,6,7in the package material2.

FIG. 7a-cshow a cross sectional views of an integrated circuit package1according to further embodiments. The package1comprises external connector elements3(cf. embodiments ofFIG. 1-3), such as a lead frame, electrically connected to an integrated circuit element4through one or more bonding wires3a. The integrated circuit element4typically comprises an IC chip and/or a semiconductor die having a sensitive surface area4a, wherein the sensing surface4ais exposed to the outside environment through an external communication channel8. The sensitive surface area4ais e.g. implemented as a MEMS (e.g. pressure measurement) or as a capacitive, temperature, optical or magnetic sensor (e.g. based on Hall or Magneto Resistive measurements).

The package material2forming the integrated circuit package1is formed in a two-step process. First, the integrated circuit element4, lead frame3and bonding wires3aare enclosed by package material (e.g. using a molding process), where the communication channel8towards the sensor surface4ais kept free from packaging material, and a first package part2bis formed. The mechanical element5(having a bore running there through) is then positioned on top of the first package part2band aligned with the external communication channel8(thus extending the external communication channel8) at least in part. In the second step, package material is again added to a further mold on top of the first package part2b, thus forming the second package part2c. When viewed from the sensing surface4a, the external communication channel8is then defined by the first package part2b, the bore of the mechanical element5, and the second package part2c.

This first package material layer2bparticularly advantageous in cases where the mechanical element5should not come into direct contact with a delicate integrated circuit element4and/or sensing surface4a. To that end, the mechanical element5is disposed on the first package material layer2binstead, resulting in an offset from the integrated circuit element4and/or sensing surface4aby a predefined distance d. Offsetting the mechanical element5may reduce any form of interference with the IC element4and or sensing surface4afor improving measurement accuracy.

In a further set of embodiments, the mechanical element5is a metal element suspended in the integrated circuit package1, e.g. using the two-step molding process as described above. In a single integrated circuit package1, one or more metal elements5may be provided. If multiple metal elements5are present, they may be interconnected in a mechanical and/or electrical sense. Furthermore, the metal element has a bar shape or a strip shape, These embodiments may be advantageously used integrated sensing integrated circuit packages1.

In the embodiment shown inFIG. 7a, the integrated circuit element4is suspended in package material2and electrically connected to the external connector elements3through the one or more bonding wires3a. In a further embodiment the integrated circuit element4may also be supported by the external connecting elements3, such as a lead frame. In yet a further embodiment, the integrated circuit package1comprises a substrate4b(e.g. a ceramic or glass substrate, possibly as part of a multi chip module, MCM). and the integrated circuit element4is supported thereby.

A further embodiment is shown inFIG. 7b, which shows a suspended mechanical element5by using the two step molding. In this case there is no contact with the semiconductor element4or a sensor element/sensing surface4aor a carrier4b(lead frame, PCB, ceramic etc). An even further embodiment is shown inFIG. 7c, which depicts a suspended mechanical element5by using the two step molding. In this case the mechanical element5is a closed version type (in this case a closed off bottom).

The above embodiments where the mechanical element5is a mechanical connection element, such as an element with an internal screw thread, may be advantageously used in an integrated circuit package1with a sensor element4and an external communication channel8. Alternatively, the mechanical element5is provided with an internal diameter larger than the sensor surface4a(or even larger than sensor die4), and attached to an underlying lead frame3or other structural frame element. This would still provide an external communication channel8that can be connected to a further element (e.g. a flexible conduit or tubing) and still providing an air tight space to the sensor surface4a.

In a further group of embodiments the mechanical element is an attachment element5of a thermoplast material partly exposed from the integrated circuit package1. The partly exposed part of die attachment element5can extend from the surface of the integrated circuit package1, or it may be flush with the surface of the integrated circuit package1, or even be (partly) below the surface of the integrated circuit package1, or even a combination thereof.

Exemplary embodiments are shown in cross sectional views inFIGS. 8aand 8b.FIG. 8ashows an embodiment, where the mechanical element is an attachment element5, which is suspended in the package material2b,2c. During assembly, the attachment element5is provided in the package material2b,2oin a two-step moulding process. The attachment element5is of a thermoplast material (as opposed to the regular duroplast or thermosetting material used as the package material2b,2c). This allows attachment of a further sub-module9to an exposed part5aof the attachment element5, as shown in the cross sectional view ofFIG. 8b. The attachment element5may further be adapted to be anchored in the package material2b,2c, e.g. by using a specific shape at the lower side. Also the further sub-module9may be provided with an extending surface profile9b, matching the surface profile of the exposed part5a.

Furthermore, the attachment element5may be substantially ring-shaped or may have a rectangular or other form, with or without an opening or aperture in a central part, and one or more attachment elements5may be provided in a single integrated circuit package1. The exposed part5amay be provided with a flat surface or other surface lay-out allowing easier attachment of the sub-module9, i.e. at the location9aas shown in the embodiment ofFIG. 8b.

Attachment of the sub-module9can be accomplished using one of several techniques exploiting the thermoplast nature of the attachment element5material, i.e. friction welding, gluing, softening using a solvent, melting/curing etc. Especially when the part of the sub-module9in contact with the attachment element5when assembled is also of a thermoplast material, attachment may be accomplished in a very efficient and robust manner.

In a further embodiment, which is shown schematically in the cross sectional view ofFIG. 9, an additional sealing element11may be used which is in contact with the package material2of the integrated circuit package1, to ensure a long lasting sealing. In the embodiment shown inFIG. 9, the upper surface of the integrated surface package1is provided with a matching sealing groove2d. Furthermore, the sub-module9in this embodiment is provided with a central aperture9c, matching an external communication channel8of the integrated circuit package1. Also, the sub-module9is provided with an extending surface profile9b, matching the exposed (and extending) part5aof the attachment element5. When the sub-module9is attached to the attachment element5(at locations9a), the melting (or other attachment method) is applied to the exposed part5aand the extending surface profile9b, until the sealing element11is properly providing a sealing function between integrated circuit package1and the sub-module9.

The sub-module9may be a complex part or just a simple extension of the integrated circuit package1, e.g. allowing mounting of further element, such as lenses, filters etc., or it may comprise further functional elements to be used in conjunction with the integrated circuit package1(e.g. tubing, valves, etc.)

The present invention embodiments have been described above with reference to a number of exemplary embodiments as shown in the drawings. Modifications and alternative implementations of some parts or elements are possible, and are included in the scope of protection as defined in the appended claims. The integrated circuit package1(and its contents) may be one of many types, and includes but is not limited to the following examples: a dual-in line package (DIL), surface mount device (SMD) package, ball grid array (BGA) package, land grid array (LGA), quad flat no-leads (QFN) package, dual flat no-leads (DFN) package, etc.