GB2432549A

GB2432549A - Moulded structural member, method of producing the member and a portable communication device including the member

Info

Publication number: GB2432549A
Application number: GB0524005A
Authority: GB
Inventors: Yonatan D Kemelman; Eli Margalit; Ariel Rotman; Sagi Spichko
Original assignee: Motorola Inc
Current assignee: Motorola Solutions Inc
Priority date: 2005-11-25
Filing date: 2005-11-25
Publication date: 2007-05-30
Also published as: GB0524005D0; WO2007062310A2; WO2007062310A3

Abstract

A shaped structural member such as a shield (209) adapted for use to provide mechanical protection in a portable communication device (200) comprises a first portion (223, 225) comprising conducting material and a second portion (213) comprising insulating material and is characterised in that the second portion comprises a tough and resilient thermoplastic organic polymeric material which has been shaped and bonded to the first portion by injection moulding. The second portion may be formed from a thermoplastic amorphous resin material such as a polycarbonate material which may beneficially include filler particles and/or reinforcing fibres for added strength and/or for matching of one or more physical properties, such as thermal expansion, of the first and second portions. The first portion may be a metallic material, such as magnesium, aluminium or titanium or an alloy based on one of these metals, which may itself have been formed by injection moulding prior to addition of the second portion. Also described is a method of producing the shaped structural member.

Description

1 2432549 TITLE: SHAPED STRUCTURAL MEMBER, METHOD OF PRODUCING THE

MEMBER AND A PORTABLE COMMUNICATION DEVICE INCLUDING THE

MEMBER

FIELD OF THE INVENTION

The present invention relates to a shaped structural member, a method of producing the member and a portable communication device incorporating the member. In particular, the invention relates to a member suitable for use as a protective shield for at least part of a portable communication device, particularly a part of the device which is required to transmit electromagnetic signals.

BACKGROUND OF THE INVENTION

In some portable communication devices structural members employed to provide mechanical strength are made of conducting material. For example, magnesium or aluminium alloys, which are lightweight and can have good mechanical strength and may be formed into intricate shapes by processes such as injection moulding, are used to fabricate such members. Such materials may also allow the structural member to have electrical and/or heat conductivity as well as mechanical strength. An example of such a conducting structural member is a protective cover or shield which is provided to give mechanical protection to at least part of a portable communication device, e.g. to avoid damage to the device in the event that the device is accidentally dropped. The cover or shield may be formed integrally with at least part of a casing structure of the device.

In some cases, it is necessary to provide a gap in the conducting structural member. For example, where the conducting structural member provides a mechanical shield for a communication device, particularly in a portion of the device where the device includes an internal antenna, the gap may be required to allow transmission and reception of electromagnetic signals by the antenna. Unfortunately, the provision of a gap may substantially weaken the mechanical protection provided by the structural member.

SUMMARY OF THE INVENTION

According to the present invention in a first aspect there is provided a shaped structural member as defined in claim 1 of the accompanying claims.

According to the present invention in a second aspect there is provided a portable communication device as defined in claim 19 of the accompanying claims.

According to the present invention in a third aspect there is provided a method of producing a shaped structural member, the method being as defined in claim of the accompanying claims.

Further features of the invention are as defined in the accompanying dependent claims and are as disclosed in the embodiments of the invention to be described.

Embodiments of the present invention will now be described by way of example. Reference will be made to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a shaped printed circuit board.

FIG. 2 is a front view of a communication handset housing the circuit board of FIG. 1 and embodying the invention.

FIG. 3 is a front perspective view of part of the handset of FIG. 2 during construction of a shield included as part of the handset.

FIG. 4 is an enlarged front view during construction of the shield included in the handset of FIGS. 2 and 3.

FIG. 5 is an enlarged front view during construction of an alternative form of shield for inclusion in the handset of FIG. 2.

FIG. 6 is a rear angled perspective view during construction of the shield of FIG. 5.

FIG. 7 is an angled rear perspective view of the shield of FIGS. 5 and 6 following completion of the shield.

FIG. 8 is a flowsheet illustrating a method of production of a shaped structural member in accordance with an embodiment of the invention.

DESCRIPTION OF EMBODI)NTS OF THE INVENTION

In embodiments of the invention, a shaped structural member adapted for use in a portable communication device comprises a first portion comprising conducting material, e.g. lightweight metallic material, and a second portion comprising insulating material. The second portion comprises a tough and resilient organic polymeric material which has been shaped and bonded to the first portion by injection moulding.

The first portion of the shaped structural member embodying the invention may comprise a product made by injection moulding of a metallic material, e.g. comprising a metal selected from magnesium, magnesium alloys containing at least 50 per cent by weight of magnesium, aluminium, aluminium alloys containing at least 50 per cent by weight of aluminium, titanium and titanium alloys containing at least 50 per cent by weight of titanium. In one embodiment a magnesium alloy containing at least 50% by weight magnesium, and especially at least 80% by weight magnesium is used. For example, a known magnesium alloy suitable to form the first portion of the shaped structural member embodying the invention is the material AZ91D (specified in the standard ASTMB 94-92) which contains by weight: 8.3%-9.7% aluminium, 0.15% manganese, 0.35% -1% zinc, other optional additives up to 1%, the balance being magnesium. Typical properties of this metallic material are as follows: tensile strength: 45 GPa; shear strength: 17 GPa; coefficient of thermal expansion: 26pm per (m.K) for the temperature range 200 to 1000.

The second portion of the structural member embodying the invention may, in one embodiment, be formed by injection moulding of a substantially non-rubbery (non-elastomeric) thermoplastic amorphous resin, e.g. one of the resins known for use in injection moulding to form tough, resilient products. The resultant organic polymeric material formed by injection moulding of such resin material has high resistance to stresses and impact caused by mechanical shock and has good dimensional stability, i.e. is not easily deformed (in contrast to elastomeric material) . In particular, the organic polymeric material of the second portion shows (at a temperature of 200 or, preferably over a temperature range of from 200 to at least 1000) a high tensile modulus, e.g. a tensile modulus of at least 1000 MPa, an elongation at break of not greater than 40%, a tensile strength at break of not less than 25 MPa and a hardness of at least 50 Rockwell R as measured in accordance with ASTM standard D 785. Furthermore, the organic polymeric material shows good creep resistance.

The resin from which the organic polymeric material is formed desirably provides easy processing for use in injection moulding, showing minimum flashing of material from the mould during such processing (such flashing producing unwanted burrs in the resultant product) and has a good surface energy which facilitates bonding to other materials. Other useful optional properties of the organic polymeric material are that it is substantially colourless but may be coloured by dyeing, e.g. to match a colour of the first portion.

The organic polymeric material of the second portion may include from 5% to 45%, in one embodiment from 15% to 35%, and especially from 20% to 25%, by weight of a reinforcing fibre material and/or a particulate filler material to provide improved mechanical and/or physical properties. Examples of reinforcing fibres include fibres selected from known fibre types, including glass fibres, carbon fibres, silica fibres and polymer fibres. Examples of polymer fibres include nylon fibres, aramid fibres and polyethylene or polypropylene fibres. Examples of known particulate fillers include inert, inorganic fillers such as calcium carbonate, silica, kaolin and the like.

For example, in one embodiment the material of the second portion is formed from an amorphous thermoplastic resin which is moulded together with from 15% to 35%, particularly from 20% to 25%, by weight of reinforcing glass fibres based on the weight of resin. Furthermore, such fibres and/or filler particles may improve the tensile strength and/or shear strength and/or other mechanical properties of the polymeric material and the second portion produced from it. The filler particles and/or reinforcing fibres may also serve to provide (an approximate) match of the coefficient of thermal expansion of the organic polymer material of the second portion to that of the metallic material of the first portion. This avoids, during the formation of the second portion by injection moulding, the formation of gaps or voids between the dissimilar materials (metallic material and organic polymeric material) and reduces the shrinkage of the organic polymeric material in the later stages of the injection moulding process.

Normally, insulating material present near to an antenna in a portable communication device has a loading effect on the RF performance of the antenna and, where the communication device has a compact shape and size, the loading effect cannot be compensated for by modifying the shape and/or size of the antenna. However, the material of the second portion of the shaped structural member embodying the invention may be selected to provide an electromagnetic window in the shaped structural member (to allow transmission through the member of electromagnetic signals to and from an antenna of a portable communication device in which the shaped structural member is provided) yet by providing a suitable dielectric properties, particularly relative permittivity (dielectric constant) and dissipation factor, which do not seriously reduce antenna performance and provide the second portion with a high transparency to electromagnetic radiation signals, particularly at a frequency of operation, e.g. from 100MHz to 10GHz.

The organic polymeric material employed to form the second portion may be selected from materials known to be suitable for injection moulding and to give the desirable properties specified above. For example, a polymeric material which contains at least 60% by weight of polycarbonate can be used. In particular, the polycarbonate resin commercially available from GE Advanced Materials under the trade name LEXAN (Registered Trade Mark), e.g. the product sold under the trade name LEXAN 500R can be used. Typical mechanical properties obtained in a shaped, injection moulded product formed from such material including 20% to 25% by weight glass fibres are as follows: (i) tensile modulus: 3300 MPa; (ii) tensile stress at break: 7 %; (iii) tensile stress at yield: 59 MPa.

In the formation of the structural member embodying the invention, the first portion, e.g. formed by injection moulding, may comprise first and second parts having a gap between them. In this case, the second portion may suitably be formed in the gap between the first and second parts of the first portion and may thereby be bonded to both of the first and second parts to seal the gap between the first and second parts.

The shaped structural member embodying the invention may comprise a member which is shaped to provide an external mechanically protective shield for at least part of a portable device. For example, the shaped structural member may be in the form of an arc shaped member which includes the first and second portions bonded together. The mechanically protective shield may be adapted to protect one or more internal components of a portable communication device, particularly in a part of the device which includes an internal antenna. The second portion of the structural member may be adapted to allow transmission and reception of electromagnetic radiation signals through the shaped structural member so that the second portion provides in the shaped structural member a window for electromagnetic radiation.

The metallic first portion of the shaped structural member, e.g. when in the form of first and second parts which are to be completed to form the shaped structural member by addition of the second portion of organic polymeric material, may conveniently be formed integrally with a metallic casing part. The casing part may be adapted to provide at least part of a casing for a portable communication device.

The shaped structural member embodying the invention may comprise an arc shaped member wherein the first portion has, comprising the first and second parts of the first portion, first and second curved arms having ends facing one another and having a gap between them. The second portion, when added, bridges and seals the gap. The second portion may include overlap portions which are bonded to each of the first and second arms on inner surfaces of the first and second arms. The arc shaped member may have a smooth outer surface profile between the first and second portions.

Where the shaped structural member embodying the invention is adapted to provide a mechanically protective shield for components in at least part of a portable communication device, it may further be adapted to provide an electrical gap in the conductivity of the shield to provide a window permitting the transmission of electromagnetic signals, e.g. to and from an antenna, in a part of the device in which it is to protect.

The shaped structural member embodying the invention formed in the manner which has been described provides a composite material product which may be used for example in a portable communication device to give an improved performance compared with conducting structural members having an unfilled gap. The member may provide an improved combination of desired mechanical and physical properties. Such a combination of properties is not obtained using known composite materials. In particular, the second portion in the shaped structural member embodying the invention provides a region of electrical insulation needed in operation of the portable communication device and not provided by the first portion of the member, yet provides this region in the form of a rigid, stable and lightweight material well bonded to the conducting material of the first portion. The second portion thereby provides together with the first portion suitable overall mechanical strength giving the structural member suitable robustness in use.

The portable communication device (e.g. handset) in which the shaped structural member embodying the invention is employed may be a portable radio, mobile telephone, data communication handset or other known portable radio communication device.

Detailed embodiments of the invention will now be described with reference to the accompanying drawings.

FIG. 1 is a front view of a shaped printed circuit board 100 for use in a portable communication handset.

The circuit board 100 includes near its top end an antenna 101 which is in the form of a platelet attached to the circuit board 100 so that the antenna 101 occupies a plane perpendicular to the plane of the circuit board 100. The antenna 101 (whose side edge only is seen in FIG. 1) is in a horizontal plane and the printed circuit board 100 is in a vertical plane, i.e. the plane of the drawing, as shown in FIG. 1. Such an antenna has a form suitable to provide a Bluetooth RF link at 2.4 GHz, although this form is illustrative only rather than limiting of the antenna forms which may be used in a handset to be described. The circuit board 100 includes mounted thereon, in addition to the antenna 101, a plurality of interconnected electronic processors and components to provide radio communications and other functions in a known manner. These processors and components are not material to the invention and so for the sake of simplicity are not shown in FIG. 1. The circuit board 100 has a shape which facilitates housing in a handset to be described with reference to FIG. 2. A curved recess 103 is provided at the top end of the circuit board 100. The printed circuit board 100 also has location holes 105. The recess 103 and the location holes 105 serve to assist location of the circuit board in a handset.

FIG. 2 is a front view of a communication handset incorporating the printed circuit board 100 fitted inside a casing 201 of the handset 200. The casing 201 is formed from a front portion and a rear portion which are fitted together to form the completed casing 201 after incorporation of the circuit board 100 and any other components required in the enclosure formed between them. The front portion only is shown in the drawings. The front portion, which is indicated by reference numeral 203, includes a body part 204 that includes speaker apertures 206 formed therein as shown in FIG. 2. The front portion 203 of the casing 201 also includes an upper part 205 which is formed integrally with the body part 204 and defines together with the body part 204 a suitable outer design shape for the handset 200. A cap indicated by a dashed line 215 fits over the upper part 205 and abuts against an upper edge of the body part 204 to provide a smooth outer surface profile together with the outer surface of the body part 204. The cap 215 is made of a lightweight, insulating, non-porous material, e.g. a moulded plastics material, to provide a waterproof and dustproof cover for the upper part 205.

The upper part 205 includes a strip 207 extending laterally across the upper part 205 and a shield 209 in the form of an arc curving around an edge of an upper end part of the printed circuit board 100. A gap 211 is formed between the strip 207 and the shield 209. The circuit board 100 including the antenna 101 mounted thereon is seen in the gap 211. The gap 211 facilitates transmission and reception of electromagnetic signals by the antenna 101. Thus, the shield 209 does not completely cover the antenna 101 but gives sufficient mechanical protection required by the circuit board 100 and components mounted on it at its upper end, particularly the antenna 101, e.g. in the event that the handset 200 is accidentally dropped in use. The shield 209 includes a downward projection including a hole 210 which serves to secure the assembly of the shield 209 and printed circuit board 100 together, e.g. by means of a thermoplastic self tapping screw (not shown) . The shield 209 includes a preformed gap in which is provided an insert portion 213. The shield 209 and the formation of the insert portion 213 therein are described in more detail later with reference to FIGS. 3 to 7.

The front portion 203 of the casing 201 (and the rear portion to be fitted to it -not shown) are made of a strong lightweight metallic material such as an alloy comprising mainly magnesium, aluminium or titanium. Use of a magnesium alloy, e.g. one which includes at least 80% by weight of magnesium, is preferred in view of the common use and availability for use of such material in the electronics industry. In particular, the alloy AZ91D referred to earlier is particularly suitable for use in forming the front portion 203 of the casing 201.

Desirably, the front portion 203 of the casing 201 including parts of the shield 209 excluding the insert portion 213 (and the gap in which it is provided) is a metallic component which is formed in one piece in a known manner by injection moulding. Cutting or milling may be applied, after shaping by injection moulding, to the front portion 203 of the casing 201, including particularly the metallic parts of the shield 209, to enhance the definition of certain features now to be described.

FIG. 3 is a front angled perspective view, during construction, of part of the front portion 203 of the casing 201, including in particular the upper part 205.

As shown in FIG. 3, the shield 209 includes a gap 221 between two projecting and facing curved metallic arms 223, 225. The arms 223 and 225 comprise the first and second parts of the first portion of the structural member embodying the invention as referred to earlier; in this case, the structural member comprises the shield 209. The arm 223 includes on its end facing the arm 225 a projecting peg 227 and the arm 225 includes on its end facing the arm 223 a projecting peg 229.

An enlarged front view of the shield 209 including the arms 223 and 225 and the pegs 227 and 229 is shown in FIG. 4. The gap 221 is bridged by the insert portion 213 shown in FIG. 2. The insert portion 213 is the second portion of the shaped structural member, in this case the shield 209, embodying the invention as referred to earlier. The insert portion 213 is formed by injection moulding in a known manner of an amorphous thermoplastic resin to provide the organic polymeric material of the second portion having the properties as specified for the second portion earlier, e.g. by use of the product LEXAN (Registered Trade Mark) 500R including from 20% to 25% by weight of glass fibres. The resultant organic polymeric material of the so formed insert portion 213 bonds directly to the metallic material of the arms 223 and 225 by the injection moulding process to form a bridge and to seal across the gap 221. The shape which the insert portion 213 forms is indicated by a dashed line in FIG. 4. The pegs 227 and 229 provide anchoring features to facilitate bonding of the moulded organic polymeric material of the insert portion 213 to the arms 223 and 225. The insert portion 213 also has overlap extensions 231 and 233 on the inner surfaces (surfaces facing toward the interior of the handset 100) of the arms 223 and 225 further to assist bonding to the arms 223 and 225. The insert portion 213 has an outer surface which forms a smooth, matching outer surface profile together with the outer surfaces of the arms 223 and 225.

An enlarged front view of an alternative form of the shield 209 including the arms 223 and 225 during construction in another embodiment of the invention is shown in FIG. 5; FIG. 6 is a rear angled perspective view during construction of the shield 209 for the same embodiment; and FIG. 7 is a rear angled perspective view for the same embodiment of the antenna shield 209 following completion by provision of the insert portion 213. In this alternative embodiment, parts which have the same reference numerals as parts in the embodiment described with reference to FIGS. 3 and 4 have the same function as such parts. In the embodiment shown in FIGS. to 7 the pegs 227 and 229 are not employed. Instead, the arm 223 includes in its end facing the arm 225 a slotted recess 235, and the arm 225 includes in its end facing the arm 223 a slotted recess 237. A rib 239 extends between the inner side faces of the slotted recess 235 and a rib 241 extends between the inner side faces of the slotted recess 237. A projecting peg 243 is formed on an inner surface of the arm 223 and a similar projecting peg 245 is formed on an inner surface of the arm 225. The insert portion 213 is again formed by injection moulding of an electrically insulating organic polymeric material as described earlier. As in the embodiment described with reference to FIGS. 3 and 4, the insert portion 213 is moulded directly onto the arms 223 and 225 to bond with the arms 223 and 225 and to bridge and seal the gap 221 between the arms 223 and 225 thereby completing the shield 209. The shape which the insert portion 213 forms again is indicated by a dashed line 213 in FIG. 5 and is shown when completed, in a rear view, in FIG. 7.

In the embodiment described with reference to FIGS. to 7, the organic polymeric material employed to produce the insert portion 213 flows in melted form into the slotted recesses 235 and 237 during the moulding process and occupies the spaces within the recesses 235 and 237 including regions behind the ribs 239 and 241.

The recesses 235 and 237 and the ribs 239 and 241 form suitable anchoring features to facilitate bonding between the organic polymeric material of the insert portion 213 and the metallic material of the arms 223 and 225. The insert portion 213 again has the overlap extensions 231 and 233 on the inner surfaces of the arms 223 and 225. The pegs 243 and 245 provide further anchoring features to assist bonding of the overlap extensions 231 and 233 to the arms 223 and 225. The insert portion 213 again has an outer surface which forms a smooth, matching outer surface profile together with the outer surfaces of the arms 223 and 225.

In the embodiment described with reference to FIGS. to 7, the slotted recesses 235 and 237 may extend through the entire thickness of the arms 223 and 225 perpendicular to the plane of the drawing in FIG. 5.

Alternatively, the slotted recesses 235 and 237 may extend, in one or more slotted portions, only partly through the thickness of the arms 223 and 225. Also, the ribs 239 and 241 may be the only ribs formed inside the slotted recesses 235 and 237. Alternatively, each of the slotted recesses 235 and 237 may include one or more further ribs or other similar parts (not shown) to act as anchoring features to assist bonding of the moulded organic polymeric material of the insert portion 213 to the arms 223 and 225.

In the above embodiments of the invention, the surfaces of the arms 223 and 225 to which the organic polymeric material of the insert portion 213 is to bond may beneficially be provided with a surface treatment which facilitates bonding. For example, the surfaces may be provided with a roughness obtained as a result of the injection moulding process employed to produce the metallic arms 223 and 225 of the shield 209.

Alternatively, or in addition, surface roughness may be enhanced by an added treatment after injection moulding of the surfaces of the arms 223 and 225, e.g. by sand blasting, and/or by texturing. Alternatively, or in addition, the surfaces may be treated by addition of a known primer to assist bonding of the material of the insert 213.

FIG. 8 is a flowsheet illustrating a method 300 of production of a shaped structural member in accordance with an embodiment of the invention. The structural member may for example be the shield 209 in the embodiments described with reference to FIGS. 2 to 7.

The method 300 includes a step 301 in which a first portion of the shaped structural member is formed by injection moulding of metallic material such as magnesium alloy in a known manner. In the example of the shield 209, the first portion comprises the arms 223 and 225. In a step 302 which is an optional step of the method 300, anchoring features of the first portion are shaped, for example by cutting or milling. In the example of the shield 209 of FIG. 3, these features include the projections 227 and 229. In a step 303 which is a further optional step of the method 300, the bonding surfaces of the first portion are prepared. In the example of the shield 209 of FIG. 3 these are the surfaces of the arms 223 and 225, including the projections 227 and 229, which are to bond to the insert portion 213. The treatment may include roughening and/or provision of a surface primer. In a step 304 which is an optional but desirable step, the first portion and the material to form the second portion, e.g. resin material to be injection moulded to form the organic polymeric of the second portion, are thoroughly dried. Desirably, the resin material is dried in an oven at a temperature greater than lOOC to give a resultant moisture content of not greater than 0.02% by weight. In a step 305 the second portion of the shaped structural member is formed by injection moulding. For example, the resin material is moulded using a conventional barrel and screw device to inject the material into a mould of the required shape to form the second portion. A clamp holds the mould and the first portion adjacent to the mould so that the second portion formed by the mould bonds to the first portion. The applied clamping pressure may suitably be in the range 40 to 80 Nmin2. In the example of the shield 209 of FIG. 2, the moulding process produces the insert portion 213 bonded to the arms 223 and 225.

In the method 300 the steps 301 and 302 may be combined in a single step and the steps 303 and 304 may be combined in a single step.

Claims

CLAIMS

1. A shaped structural member comprising a first portion comprising conducting material and a second portion comprising insulating material and characterised in that the second portion comprises organic polymeric material which has been shaped and bonded to the first portion by injection moulding, wherein the organic polymeric material is a thermoplastic material.

2. A shaped member according to claim 1 wherein the first portion comprises first and second parts having a gap between them and the second portion is formed in the gap and is bonded to both of the first and second parts to seal the gap between the first and second parts.

3. A shaped member according to claim 1 or claim 2 wherein the first portion comprises a metallic portion which has been produced by injection moulding.

4. A shaped member according to any one of the preceding claims which comprises an arc shaped member which includes the first and second portions.

5. A shaped member according to claim 4 wherein the arc shaped member is adapted for use in a portable communication device and is adapted to provide a mechanical shield for one or more components of the portable communication device.

6. A shaped member according to claim 5 wherein the first portion of the arc shaped member is formed integrally with at least part of a casing of the portable communication device.

7. A shaped member according to any one of the preceding claims wherein the first portion comprises a product made by injection moulding of a metallic material consisting of a metal selected from magnesium, magnesium alloys containing at least 50 per cent by weight of magnesium, aluminium, aluminium alloys containing at least 50 per cent by weight of aluminium, titanium and titanium alloys containing at least 50 per cent by weight of titanium.

8. A shaped member according to any one of the preceding claims wherein the second portion is produced from injection moulding of a thermoplastic, amorphous non-rubbery resin.

9. A shaped member according to any one of the preceding claims wherein the organic polymeric material of the second portion includes from 5 per cent to 45 per cent by weight of a particulate filler and/or a reinforcing fibre material.

10. A shaped member according to claim 9 wherein the reinforcing fibre material comprises one or more of glass fibres, carbon fibres, silica fibres and polymer fibres.

11. A shaped member according to claim 10 wherein the thermoplastic polymeric material contains from 15 per cent to 35 per cent by weight of glass fibres.

12. A shaped member according to any one of claims 8 to 11 wherein the thermoplastic material comprises at least 60% by weight polycarbonate.

13. A shaped member according to any one of the preceding claims wherein the material of the second portion has one or more of the following mechanical properties measured at a temperature of 20 degrees Celsius: (1) a tensile modulus of at least 1000 NPa; (ii) an elongation at break of not greater than 40%; (iii) a tensile strength at break of not less than 25 MPa; and (iv) a hardness of at least 50 Rockwell R as measured in accordance with ASTM standard D 785.

14. A shaped member according to any one of the preceding claims wherein the first portion includes at least one anchoring feature to facilitate bonding of the material of the second portion to the material of the first portion.

15. A shaped member according to claim 14 wherein the anchoring feature comprises at least one of the following: a projection, a recess, a rib or other part within a recess and a part having a roughened surface.

16. A shaped member according to any one of the preceding claims which comprises an arc shaped member wherein the first portion has first and second curved arms having ends facing one another and having a gap between them and the second portion bridges and seals the gap, wherein the second portion has overlap portions which are bonded to each of the first and second arms on inner surfaces of the first and second arms.

17. A shaped member according to any one of claims 1 to 16 which comprises an arc shaped member wherein the first portion has first and second curved arms having ends facing one another and having a gap between them and the second portion bridges and seals the gap, wherein the arc shaped member has on an outer surface a smooth outer surface profile between the first and second portions.

18. A shaped member according to any one of the preceding claims which is adapted to provide a mechanical shield for at least part of a portable communication device and the second portion is adapted to provide a window in the shield for the transmission of electromagnetic signals to and from an antenna.

19. A portable communication device including an antenna for transmission and reception of electromagnetic signals and a mechanical shield for the device, wherein the shield comprises a shaped member according to claim 18.

20. A method of producing a shaped structural member including forming a first portion comprising conducting material and a forming a second portion comprising insulating material and characterised in that the second portion comprises a thermoplastic organic polymeric material and the step of forming the second portion comprises shaping the second portion and bonding the second portion to the first portion by injection moulding.

21. A shaped member according to claim 1 or a portable communication device according to claim 19 and substantially as described herein with reference to the accompanying drawings.

22. A method according to claim 20 wherein the step of forming the first portion comprises shaping the first portion by injection moulding.