The present invention relates to a method of manufacturing an electronic card, such as the type of card known as a smartcard. Particularly, the present invention relates to a method of manufacturing an electronic card that includes a biometric sensor.

A smartcard is a pocket-sized card with an embedded integrated circuit. A smartcard typically contains volatile and non-volatile memory and microprocessor components.

A typical smartcard is manufactured by laminating a printed circuit assembly between two layers of plastic. Polyvinyl chloride (PVC) is commonly used for this purpose as it softens before it oxidises and, at suitably high temperatures and pressures, will flow and conform to the shape of components on the printed circuit assembly. When using PVC, or similar substances, the laminating temperatures required can be as high as 250°C.

Smartcards provide a way of authenticating the bearer of the card and carrying a secure message from the card to the reader. For example, if a

"nonsmart" credit card were to be lost or stolen, an unauthorised user would be able to use the credit card until the credit card is cancelled. Conversely, a "smart" credit card may include many more levels of security that would prevent such use by an unauthorised user. One such security measure that may be used with a smar-tcard is the analysis of biometric data to positively identify the bearer of the card. A biometric security measure may be added to a smartcard through the addition of a biometric sensor, such as a fingerprint sensor, on the card. In the case of a fingerprint sensor when the smartcard is to be used, the bearer presents their finger or thumb to the sensor which then allows for an associated processor to positively identify the owner of the finger or thumb and hence confirm that the user is an authorised user of the smartcards

Smartcards have developed considerably over the last few years, and the industry has had to implement innovative manufacturing methods for integrating all components within the card while also aiming to meet ISO 7810 and ISO 7816 specifications for the cards.

WO 2013/160011 discloses a method for manufacturing a smartcard in which the use of a biometric sensor is facilitated by producing a preformed card body including a circuit having contacts for connection to the biometric sensor, the contacts being embedded within the preformed card body and then forming a cavity in the preformed card body to expose the contacts. Thus, according to WO

2013/160011 the card body including a circuit can be preformed by a conventional technique, with a cavity later being formed to expose contacts and allow insertion of the biometric sensor. This concept provides significant advantages and allows for a biometric sensor to be used without exposure of the biometric sensor to high temperatures and pressures during the preforming process, which is typically a lamination process. However, there remains a need for further advance in this area in order to ensure that electronic cards such as smartcards can be manufactured reliably whilst including complicated and potentially sensitive electronics

Viewed from a first aspect, the present invention provides a method of manufacturing an electronic card, wherein the finished electronic card comprises a flexible electronic circuit, an upper protective layer located above the flexible electronic circuit and being larger in area than the flexible electronic circuit, a lower protective layer located below the flexible electronic circuit and being larger in area than the flexible electronic circuit, and multiple components mounted on an upper surface of the flexible electronic circuit; the method comprising: forming the upper protective layer with one or more indent(s) on a lower surface thereof, the or each indent being for receiving one or more of the component(s) on the upper surface of the electronic circuit, wherein the indent(s) are larger than the respective

component(s); assembling the upper protective layer with the flexible electronic circuit and the lower protective layer; and attaching the protective layers to the flexible electronic circuit and to each other to thereby enclose the flexible electronic circuit within the upper and lower protective layers; such that the indent(s) form relief volume(s) around the component(s) allowing the component(s) to be shielded from stresses induced in the protective layers during bending of the electronic card when it is in use.

By the use of one or more indent(s) formed in the upper protective layer before assembly, with these indents being larger than the component(s) that they are intended to receive, it is possible to allow for effective manufacture of the electronic card whilst also ensuring that the finished product has a reduced risk of damage from bending and other stresses applied to the card. Problems have been identified with prior art manufacturing methods especially when components on the flexible electronic circuit have varying sizes and hence they protrude from the circuit by differing amounts. The components mounted to the flexible electronic circuit lead to challenges during assembly. For example, when hot lamination is used then it is common to melt, crack or crush the electronic components. On the other hand, if cold lamination is used then there may be air pockets interspersed within the card after assembly and the mechanical properties of the finished card also differ greatly from those of traditional hot-laminated PVC cards, which can be a disadvantage. By providing a protective layer having indents for receiving the component(s) of the flexible electronic circuit later assembly of the card can proceed with a reduced risk of damage to the component(s), since they are shielded and enclosed by the protective layer.

Hot lamination may be used in order to join the layers together and fuse the two protective layers around the flexible electronic circuit. This could be done by use of only the parts of the protective layers that extend in size greater than the flexible electronic circuit. There may also be one or more orifice(s) through the flexible electronic circuit enabling fusing of the upper protective layer to the lower protective layer through the orifice. The use of one or more orifice(s) in this way can strengthen the bond between the protective layers and therefore increase the structural integrity of the encapsulation of the flexible electronic circuit. It can also reduce or entirely avoid the need for resins that bond the protective layers to the electronic circuit.

In the case of multiple indents, the components of the electronic circuit that are received within the indents may protrude from the surface of the electronic circuit by differing amounts, with the indents hence extending into the upper protective layer by correspondingly differing amounts. The indents are larger than the component(s) that they receive and by this it is meant that there is a gap around all of the sides and the top(s) of the component(s) once the upper protective layer and the flexible electronic circuit are fitted together, so that the relief volume(s) extend around all of the sides and the top of each component. The size of the gap is preferably set to provide enough space between the components and the material of the upper protective layer to allow for the electronic card to withstand bending without undue pressure or shear forces being generated. For example, the size of the gap may be set based upon forces and/or deformation generated during mandated testing as defined in the ISO standards for smartcards.

The width of the gap around the component(s) may be at least 5 μηι around all sides and the top of the component(s), for example the width may be in the range 5-30 pm inclusive or perhaps 5-20 pm inclusive. The relief volume and hence the size of the gap may be larger for components of greater size in order to account for the potentially larger bending and shearing loads across greater extents of the card. In particular the relief volume may be larger for components that extend outward further from the flexible electronic circuit than for components that extend a lesser distance outward from the flexible electronic circuit. The indents may be formed with a radius of at least 0.5pm around all internal and external corners of the indents and of the lower edges of the indents. This aids in avoiding stress concentrations.

It is preferred for the method to include the addition of a cushioning material within the relief volumes during or prior to assembly of the protective layers with the flexible electric circuit. It can be advantageous to fill the relief volumes with a cushioning material rather than leave them as voids filled with air since the electronic circuit is then both protected from impact damage by the cushioning effect of the material as well as being resistant to damage when the card is flexed during use. Filling the relief volumes with a cushioning material also reduces the risk that one of the protective layers might collapse into the relief volume causing damage to the card and/or to the components of the flexible electronic circuit. The cushioning material may be a lower density material than the material of the protective layers. The cushioning material may be a material that is capable of greater deformation in compression and in shear than the material of the components of the electric circuit and the material of the protective layers. In some examples the cushioning material is a resilient material and hence undergoes elastic deformation when deforming forces are applied to the card. In this case the cushioning material may be capable of greater elastic deformation in compression and in shear than the material of the components of the electric circuit and the material of the protective layers.

Some possible materials for use as the cushioning material include epoxy resins, polyurethanes, or silicones. The cushioning material may be solid or it may include a foam material. Advantageously the cushioning material is a material selected for good adhesion to the material(s) of the protective layers.

The upper protective layer and the lower protective layer may be of about the same size in terms of their length and width dimensions. Their thickness may differ. Typically, the upper protective layer will be thicker than the lower protective layer due to the need to allow space for the indents into the material of the upper protective layer. The protective layers may both be made of the same material. This allows for greater freedom in selecting materials and processes used for attaching the protective layers to each other. The total thickness of the lower protective layer may be in the range 20-100 μηι. If the electronic card is intended to be provided with a magnetic strip on the lower surface of the lower protective layer, which is an optional feature, then it is advisable to have a minimum thickness of about 80 μπι. In cases where there is no magnetic strip then the lower protective layer may be of lesser size to minimise the card thickness and/or allow for a greater thickness to house the internal components. The total thickness of the upper protective layer may be in the range 500-600 μηι, for example about 540 μιη. The total thickness of the upper protective layer may be set based on the maximum extent of the largest component of the flexible electronic circuit to be fully housed within an indent, plus an additional thickness providing protection above the largest component of the flexible electronic circuit that is required to be fully housed within an indent. The thickness of the upper protective layer between an upper surface of the upper protective layer and the top surface of the indent that extends furthest into the upper protective layer may be in the range 20-100 μηι, for example about 80 μητ As discussed below this thickness may be provided as material integral to the material that forms the indents, or it may be a separate body of material so that the upper protective layer is formed of a first indent layer, and then a second, upper, layer placed atop the indent layer. In a typical set of components the "tallest" component on the flexible electronic circuit is 460 μιτι and the example thickness allows for about 80 μηι of the upper protective layer atop this component (minus the gap that creates the relief volume) when the total thickness is about 540 μηη.

In some examples the upper protective layer includes a single body of material providing the material around indents as well as the upper surface of the upper protective layer and also optionally the part(s) of the upper protective layer that extend in size greater than the flexible electronic circuit can be all formed from a single body of material. This can be done using various techniques as discussed below. In an alternative arrangement the upper protective layer may be formed from multiple bodies of material, optionally using different materials having differing properties. In particular, the upper protective layer may include: a first body of material forming a bottom part of the upper protective layer and including the indents as well as material extending over the top of the indents, at least for indents smaller than the deepest indents; and a second body of material forming a top part of the upper protective layer and spanning across all of the indents as well as optionally forming the part(s) of the upper protective layer that extend in size greater than the flexible electronic circuit.

The material of the protective layers may be any material used in conventional electronic cards, for example it may be PVC or PE. PVC is most commonly used and hence is selected in the example embodiment as discussed below.

It should be noted that as used herein references to relative locations such as upper, lower, top and bottom are specified relative to an upper and lower direction of the flexible electronic circuit in which the upper direction references parts at the surface of the circuit upon which the majority of components or all of the components are mounted, and the lower direction references parts at the other surface of the circuit.

The indent(s) can be formed in the relevant part of upper protective layer by any suitable process, including removal of material to create cavities providing the indents or additive manufacturing to "build" the walls around the indents. Various processes are available, including 3-D printing, over-moulding, injection moulding, embossing, milling and/or etching. Combinations of processes may be used. In some examples milling is used to remove material from a starting body of material and thereby create cavities providing the indents. The milling may involve using a precision end mill, a water mill and/or a laser mill. In the case where a single body of material is used to provide the entirety of the upper protective layer then the material may first be reduced in thickness after being mounted in an appropriate machining device, thereby allowing a lesser thickness than could be easily handled with a sheet of the material when not mounted. The thickness reduction could be achieved by grinding or milling, for example. Preferably, subsequent processing to form the indents occurs on the same face of the material that has been previously machined to reduce the total thickness. The total thickness of the material may be reduced to 700 pm or below, for example about 635 μηη.

There may be multiple indents with each indent of the multiple indents being for holding one or more components of the electronic circuit. Each component of the electronic circuit may be provided with a dedicated indent.

The upper protective layer may further include one or more hole(s) extending downward from the upper surface of the upper protective layer either aligned with or separate from the indents that extend upward from the lower surface of the upper protective layer. The holes may include one or more blind hole and/or one or more through hole, a through hole being a hole that extends through the entirety of the thickness of the upper protective layer. In some cases an electronic card may include components that need to be mounted to the card from outside of the upper protective layer, such as biometric sensors and/or payment chips such as those used for so-called "chip and pin" bank cards. The use of one or more hole(s) extending from the upper surface of the upper protective layer in conjunction with the indent(s) on the lower surface of the upper protective layer can increase the ease of manufacture of an electronic card including such components. It should be noted that a through hole could equivalently be considered as an open indent, i.e. an indent that extends all the way through the thickness of the card, and such an indent or through hole could be formed from the upper surface or from the lower surface of the card. The hole(s) may be formed using one of the techniques referenced above in connection with formation of the indent(s). Conveniently, the same method may be used for formation of the indent(s) and for formation of the hole(s).

A through hole may be formed by first forming an indent from the lower surface of the upper protective layer almost all the way through the thickness of the upper protective layer, and then opening the hole and forming a through hole by removing the remainder of the materia! from the upper surface of the upper protective layer.

The upper protective layer may include a through hole for receiving a biometric sensor, this through-hole hence being positioned aligned with contact points on the electronic circuit for electrical connection of the biometric sensor. The through-hole for the biometric sensor may be completed after assembly of the layers and attachment of the layers to each other. Alternatively the through-hole may be fully open before assembly and may remain open during the lamination process.

The upper protective layer may be formed with through holes for connection of a component mounted to the upper surface of the electronic card to one of the components mounted on the flexible electronic circuit and received within an indent. Hence, there may be through holes that are smaller in size than the indent and extend through the material at the top of the indent to provide openings

corresponding to the location(s) of electrical contact pad(s), for example for connection of a payment chip mounted on the surface of the card to corresponding components mounted on the flexible electronic circuit. Preferably these small through holes are formed by removing material after assembly of the layers of the card and after the layers are attached together. This sequence of steps means that payment chips with alternative contact pad configurations can be used with the same design of card since the holes for the contact pads are not formed until after the card has been manufactured and when the type of payment chip is known. This sequence of steps can also provide advantages more generally when it is required to provide some protection for sensitive components of the flexible electronic circuit during the assembly and attachment process, especially when hot lamination is being performed. With the use of through holes of this type the upper protective layer may also be formed with a larger blind hole extending towards the indent beneath the upper surface of the upper protective layer, with the smaller through holes then being formed in the bottom of the larger blind hole. This allows for the indent to receive and protect components of the flexible electronic circuit such as contact pads or the like, whilst the larger blind hole allows for components that are mounted from the upper surface of the card to be recessed into the card thereby avoiding unwanted protrusions and excessive thickness of the card.

It is preferred for the upper surface of the upper protective layer and optionally the lower surface of the lower protective layer to be generally flat. The method may hence include using a flat substrate to form the upper and/or lower protective layers. The card surfaces may be flat enough to meet ISO requirements for smartcards. An overlay, such as a printed overlay, may be provided on one or both of the outer surfaces after the protective layers and the flexible electronic circuit have been attached together.

The components mounted on the flexible electronic circuit preferably include a biometric sensor and in this case the upper protective layer may include a through-hole providing an opening to expose contacts on the flexible electronic circuit that are arranged for electrical connection to the biometric sensor. The number and layout of contacts may vary depending on the configuration of connection points in the sensor. The contacts may be gold or gold plated.

The method may comprise connecting a biometric sensor to the contacts within the through hole. Preferably the biometric sensor is for identification of an authorised user of the electronic card. The electronic card may be arranged to be operable only when the biometric sensor provides an indication of an authorised user. In a preferred embodiment, the biometric sensor is a fingerprint sensor, for example a fingerprint swipe sensor or a fingerprint area sensor. The walls of the through hole for receiving the biometric sensor may be coated with an adhesive epoxy prior to the biometric sensor being inserted. The adhesive epoxy seals the sensor in place to prevent the biometric sensor becoming dislodged and being disconnected from the circuit. Alternatively or additionally the biometric sensor may be mounted to the circuit using surface mounting technology.

A conductive epoxy may be used to connect the biometric sensor to the contacts. This ensures a good ohmic contact between the sensor and the contacts within the through hole. The conductive epoxy may be selected so that its curing temperature is low enough not to damage the biometric sensor. For example, the conductive epoxy may have a curing temperature of less than 100°C, more preferably less than 60°C, this being a typical maximum designed operating temperature for many biometric sensors. An epoxy that cures at room temperature may be used.

The conductive epoxy may be an anisotropic conductive adhesive such as an anisotropic conductive paste or an anisotropic conductive film. The use of anisotropic conductive means that substantial conduction does not occur between the contacts even if any of the adhesive spills over or overlaps between the contacts. This allows more freedom in selecting the technique/apparatus that applies the conductive adhesive, since less accuracy is required.

The flexible electronic circuit may include a processor and a memory.

Where a biometric sensor is also present then the memory may be arranged to store biometric information relating to bearer of the card and the processor may be arranged to compare the stored biometric information to biometric information acquired by the biometric sensor. Thus, the processor is preferably arranged to determine if the user is an authorised user based on an indication provided by the biometric sensor. The processor and memory may also be arranged to store and transmit other information associated with the electronic card to a reader, wherein the transmitted information does not include the stored biometric information and the biometric information acquired by the biometric sensor. The processor is preferably arranged such that the biometric information acquired from the sensor is never transferred from the card during normal operation. The electronic card may include an antenna for wireless transmission of data, for example via RFID or similar. The electronic card may include a payment chip, optionally mounted as discussed above. An example embodiment includes a payment chip together with a biometric sensor and the processor is arranged to permit some or all financial transactions only if the identity of the user is confirmed as an authorised user by the biometric sensor.

The method of the above aspect may be used to manufacture electronic cards for a number of purposes where it is necessary for the identity of the bearer of the electronic card to be verified. For example, an electronic card manufactured in accordance with the above aspect may be any one of: an access card; a credit card; a debit card; a pre-pay card; a loyalty card; an identity card; and a

cryptographic card. As discussed above, the electronic card is preferably arranged to be inoperable if the biometric sensor does not provide an indication of an authorised user. Thus, the electronic card may provide its desired function, or full functions, only when the biometric information confirms that the user is authorised. For example, where the electronic card is an access card, the access card may provide access only when the user is authorised.

The method may include forming multiple upper protective layers together, for example from a single sheet of material. The assembly process may then include providing a flexible electronic circuit for each upper protective layer, along with other associated parts (such as the cushioning material), providing a lower protective layer for each upper protective layer and flexible electronic circuit, and then attaching each set of parts together to form multiple cards which may then be separated, for example via cutting or stamping to form multiple individual cards.

Whilst the discussion above is focused on the situation where components protrude only from one surface of the flexible electronic circuit it is appreciated that in some scenarios it may be required to also have components protruding from the second surface, i.e. from the lower surface. In that case the lower protective layer could include one or more indent(s) and/or hole(s) formed in a similar manner and for similar purposes to those of the upper protective layer as described above.

Viewed from a second aspect the present invention provides an electronic card including a circuit having contacts and a biometric sensor connected to the contacts, the electronic card having been formed by any of the above methods.

In another aspect, the present invention provides an electronic card comprising: a flexible electronic circuit, an upper protective layer located above the flexible electronic circuit and being larger in area than the flexible electronic circuit, a lower protective layer located below the flexible electronic circuit and being larger in area than the flexible electronic circuit, and multiple components mounted on an upper surface of the flexible electronic circuit; wherein the upper protective layer includes one or more indent(s) on a lower surface thereof, each indent receiving one or more of the component(s) on the upper surface of the electronic circuit, wherein the indent(s) are larger than the respective component(s); wherein the protective layers are attached to the flexible electronic circuit and to each other to thereby enclose the flexible electronic circuit within the upper and lower protective layers; and wherein the indent(s) form relief volume(s) around the component(s) allowing the component(s) to be shielded from stresses induced in the protective layers during bending of the electronic card when it is in use.

This electronic card provides advantages as discussed above in relation to the first aspect and may include any of the optional features or combinations of features mentioned above.

In the case of multiple indents, the components of the electronic circuit that are received within the indents may protrude from the surface of the electronic circuit by differing amounts, with the indents hence extending into the upper protective layer by correspondingly differing amounts. The indents are larger than the component(s) that they receive and by this it is meant that there is a gap around all of the sides and the top(s) of the component(s) once the upper protective layer and the flexible electronic circuit are fitted together, so that the relief volume(s) extend around all of the sides and the top of each component. The size of the gap is preferably set to provide enough space between the components and the material of the upper protective layer to allow for the electronic card to withstand bending without undue pressure or shear forces being generated. For example, the size of the gap may be set based upon mandated testing as defined in the ISO standards for smartcards.

The width of the gap around the components may be at least 5 pm around all sides and the top of the components. The relief volume and hence the size of the gap may be larger for components of greater size in order to account for the potentially larger bending and shearing loads across greater extents of the card. The indents may have a radius of at least 0.5 μητι around all internal and external corners of the indents and of the lower edges of the indents.

The card may include a cushioning material within the relief volumes. The cushioning material may be a material that is capable of greater deformation in compression and in shear than the material of the components of the electric circuit and the material of the protective layers. In some examples the cushioning material is a resilient material and hence undergoes elastic deformation when deforming forces are applied to the card. In this case the cushioning material would be capable of greater deformation in compression and in shear than the material of the components of the electric circuit and the material of the protective layers.

Some possible materials for use as the cushioning material include epoxy resins, polyurethanes, or silicones. The cushioning material may be solid or it may include a foam material. Advantageously the cushioning material is a material selected for good adhesion to the material(s) of the protective layers.

The upper protective layer and the lower protective layer may be of about the same size in terms of their length and width dimensions. Their thickness may differ. Typically, the upper protective layer will be thicker than the lower protective layer due to the need to allow space for the indents into the materia! of the upper protective layer. The protective layers may both be made of the same material. The total thickness of the lower protective layer may be in the range 60-100 μηι, for example about 80 μιτι. The total thickness of the upper protective layer may be in the range 500-600 μηι, for example about 540 μιτι. The thickness of the upper protective layer between an upper surface of the upper protective layer and the top surface of the indent that extends furthest into the upper protective layer may be in the range 60-100 μιη, for example about 80 pm. In a typical set of components the "tallest" component on the flexible electronic circuit is 460 μηι and the example thickness allows for about 80 μνη of the upper protective layer atop this component (minus the gap that creates the relief volume) when the total thickness is about 540 μηι.

In some examples the upper protective layer includes a single body of material providing the material around indents as well as the upper surface of the upper protective layer and also optionally the part(s) of the upper protective layer that extend in size greater than the flexible electronic circuit can be all formed from a single body of material. In an alternative arrangement the upper protective layer may be formed from multiple bodies of material, optionally using different materials having differing properties. In particular, the upper protective layer may include: a first body of material forming a bottom part of the upper protective layer and including the indents as well as material extending over the top of the indents, at least for indents smaller than the deepest indents; and a second body of material forming a top part of the upper protective layer and spanning across all of the indents as well as optionally forming the part(s) of the upper protective layer that extend in size greater than the flexible electronic circuit. The indent(s) can be indent(s) that were formed in the relevant part of upper protective layer by various process, including removal of material to create cavities providing the indents or additive manufacturing processes to "build" the walls around the indents. Various processes are available, including 3-D printing, over- moulding, injection moulding, embossing, milling and/or etching. Combinations of processes may be used. In some examples milling is used to remove material from a starting body of material and thereby create cavities providing the indents. The milling may involve using a precision end mill, a water mill and/or a laser mill. In the case where a single body of material is used to provide the entirety of the upper protective layer then the material may first be reduced in thickness after being mounted in an appropriate machining device, thereby allowing a lesser thickness than could be easily handled with a sheet of the material when not mounted. The thickness reduction could be achieved by grinding or milling, for example.

Preferably, subsequent processing to form the indents occurs on the same face of the material that has been previously machined to reduce the total thickness. The total thickness of the material may be reduced to 700 pm or below, for example about 635 pm.

There may be multiple indents with each indent of the multiple indents being for holding one or more components of the electronic circuit. Each component of the electronic circuit may be provided with a dedicated indent.

The upper protective layer may further include one or more hole(s) extending downward from the upper surface of the upper protective layer either aligned with or separate from the indents that extend upward from the lower surface of the upper protective layer. The holes may include be one or more blind hole and/or one or more through hole, a through hole being a hole that extends through the entirety of the thickness of the upper protective layer. In some cases an electronic card may include components that need to be mounted to the card from outside of the upper protective layer, such as biometric sensors and/or payment chips such as those used for so-called "chip and pin" bank cards The use of holes extending from the upper surface of the upper protective layer in conjunction with the indents on the lower surface of the upper protective layer can increase the ease of manufacture of an electronic card including such components. It should be noted that a through hole could equiva!ently be considered as an open indent, i.e. an indent that extends all the way through the thickness of the card, and such an indent or through hole could be formed from the upper surface or from the lower surface of the card. The hole(s) may have been formed using one of the techniques referenced above in connection with formation of the indent(s).

The upper protective layer may include a through hole for receiving a biometric sensor, this through-hole hence being positioned aligned with contact points on the electronic circuit for electrical connection of the biometric sensor.

The upper protective layer may include through holes for connection of a component mounted to the upper surface of the electronic card to one of the components mounted on the flexible electronic circuit and received within an indent. Hence, there may be through holes that are smaller in size than the indent and extend through the material at the top of the indent to provide openings

corresponding to the location of electrical contact pad, for example for connection of a payment chip mounted on the surface of the card to corresponding components mounted on the flexible electronic circuit. With the use of through holes of this type the upper protective layer may also include a larger blind hole extending towards the indent beneath the upper surface of the upper protective layer, with the smaller through holes being in the bottom of the larger blind hole.

It is preferred for the upper surface of the upper protective layer and optionally the lower surface of the lower protective layer to be generally flat. The card may include an overlay, such as a printed overlay, on one or both of these outer surfaces. The card surfaces may be flat enough to meet ISO requirements for smartcards.

The components mounted on the flexible electronic circuit preferably include a biometric sensor and in this case the upper protective layer may include a through-hole providing an opening to expose contacts on the flexible electronic circuit that are are arranged for electrical connection to the biometric sensor, which is mounted in the through hole. The number and layout of contacts may vary depending on the configuration of connection points in the sensor. The contacts may be gold or gold plated.

Preferably the biometric sensor is for identification of an authorised user of the electronic card. The electronic card may be arranged to be operable only when the biometric sensor provides an indication of an authorised user. In a preferred embodiment, the biometric sensor is a fingerprint sensor, for example a fingerprint swipe sensor or a fingerprint area sensor.

The biometric sensor may be held in the through hole with an adhesive epoxy. A conductive epoxy may connect the biometric sensor to the contacts. The conductive epoxy may be selected so that its curing temperature is low enough not to damage the biometric sensor. For example, the conductive epoxy may have a curing temperature of less than 100°C, more preferably less than 60°C, this being a typical maximum designed operating temperature for many biometric sensors. An epoxy that cures at room temperature may be used. The conductive epoxy may be an anisotropic conductive epoxy.

The flexible electronic circuit may include a processor and a memory.

Where a biometric sensor is also present then the memory may be arranged to store biometric information relating to bearer of the card and the processor may be arranged to compare the stored biometric information to biometric information acquired by the biometric sensor. Thus, the processor is preferably arranged to determine if the user is an authorised user based on an indication provided by the biometric sensor. The processor and memory may also be arranged to store and transmit other information associated with the electronic card to a reader, wherein the transmitted information does not include the stored biometric information and the biometric information acquired by the biometric sensor. The processor is preferably arranged such that the biometric information acquired from the sensor is never transferred from the card during normal operation. The electronic card may include an antenna for wireless transmission of data, for example via RFID or similar. The electronic card may include a payment chip, optionally mounted as discussed above. An example embodiment includes a payment chip together with a biometric sensor and the processor is arranged to permit some or all financial transactions only if the identity of the user is confirmed as an authorised user by the biometric sensor.

The electronic card may be any one of: an access card; a credit card; a debit card; a pre-pay card; a loyalty card; an identity card; and a cryptographic card. As discussed above, the electronic card is preferably arranged to be inoperable if the biometric sensor does not provide an indication of an authorised user. Thus, the electronic card may provide its desired function, or full functions, only when the biometric information confirms that the user is authorised. For example, where the electronic card is an access card, the access card may provide access only when the user is authorised.

Whilst the discussion above is focused on the situation where components protrude only from one surface of the flexible electronic circuit it is appreciated that in some scenarios it may be required to also have components protruding from the second surface, i.e. from the lower surface. In that case the lower protective layer could include one or more indent(s) and/or hole(s) formed in a similar manner and for similar purposes to those of the upper protective layer as described above.

Certain preferred embodiments of the present invention will now be described in greater detail by way of example only and with reference to the accompanying schematic drawings, in which:

Figure 1 illustrates materia! ready for forming into an upper protective layer for an electronic card;

Figure 2 shows the material of Figure 1 with indents formed along with a through-hole partially completed at the left-hand side of the Figure;

Figure 3 shows the material of Figure 2 with the through-hole now completed;

Figure 4 shows the upper protective layer with the addition of a blind hole above one of the indents so that it is ready for assembly with a flexible electronic circuit;

Figure 5 shows the upper protective layer of Figure 4 assembled together with a flexible electronic circuit, a biometric sensor and a lower protective layer; and Figure 6 shows the assembly of Figure 5 with the addition of small through- holes at the base of the blind hole and a payment chip.

It should be noted that for clarity the thicknesses of the various parts shown in the Figures has been exaggerated significantly. In implementations of electronic cards of the type illustrated in the Figures the width of the card might be 7cm whereas the thickness of the card would be less than 1 mm: a total thickness between the outer layers of 762 m is typical for an ID-1 card that is ISO7810 compliant. The example electronic card takes the form of a biometric authorised smartcard as shown in Figure 6 and uses an upper protective layer 101

manufactured and assembled with other parts of the card as shown in Figures 1 to 5. A Flexible Printed Circuit Board Assembly ("FPCBA") 103 contains a plurality of components 102 of varying heights and area as well as in particular a biometric sensor 107, for example a fingerprint area sensor, and a payment chip 105, which may be of the type used for "chip and pin" bank cards. Most of the FPCBA 103 components 102 need to be protected within an upper protective layer 101 and lower protective layer 108 of the card. In this example these are PVC layers as used in conventional laminated cards. However the biometric sensor 107 and the payment chip 105 need to be exposed through cut-outs on the upper protective layer 101.

As illustrated in Figures 2-4 the upper protective layer 101 is flat and in the example method it is milled across the entire surface that is intended to be placed on top of the FPCBA 103, i.e. the lower surface in the Figures, reducing the final thickness across the substrate as required. Subsequently, Computerized

Numerically Controlled (CNC) milling on that same surface of the upper layer 101 is used to form indented pockets 20 for the components 102 so that the components 102 are received within the indented pockets 20 when the upper layer 101 is laid upon the FPCBA 103.

A through hole 22 is milled to create a hole 22 to allow the biometric sensor 107 to be mounted to the FPCBA 103 and to protrude through the top of the upper protective layer 101. For the payment chip 105, an indentation 24 is milled on the underside of the upper protective layer 101 to accommodate the contact pads 106 that are on the FPCBA 103. A hole 26 is also milled on the top of the upper protective layer 101 for the payment chip 105 to rest in.

The FPCBA is placed between the upper protective layer 101 and a lower protective layer 108, which can also be made of PVC, as shown in Figure 5. The various indentations 20, 24 on the lower surface of the upper protective layer 101 are filled with a cushioning material such as an epoxy resin. The biometric sensor 107 is inserted and secured with an electrical connection to the FPCBA 103, for example using conductive epoxy. The three layers are then permanently adjoined with whatever resin filler or adhesive is selected. This can be the same as the epoxy resin selected for the cushioning material. Once it is determined which payment module will be integrated, openings 28 are milled to correspond with the contact pads 106 on the FPCBA 103, thereby allowing connectivity between the payment chip 105 and the FPCBA 103. The process is complete when a transparent/printed cover lay is adhered to the outer surfaces of the upper and lower protective layers.

As described above the various indents 20, 22, 24 on the lower surface of the upper protective layer 101 are formed to be slightly larger than the component 102, 107, 106 to be received within the indents 20, 22, 24. This serves to protect the component 102, 107, 106 from damage caused by inevitable but unintended bending and torsion inflicted by the user. The use of a cushioning material further enhances the protection of the component 102, 107, 106. The method produces a smartcard that meets ISO 7810 and 7816 specifications, whilst also providing various advantages. Milling the upper PVC layer down to a reduced thickness, e.g. 635 μηπ, removes the typical manufacturing process of using a laminate over the FPCBA 103. A laminate cannot be used in this instance because the FPCBA 103 is not a flat surface. The varying protrusions on the FPCBA 103 would otherwise create problems when trying to work with either hot or cold laminations during the later manufacturing steps. It is common to melt, crack, or crush components like those on the FPCBA 103 when attempting hot lamination, and cold lamination results in air pockets interspersed throughout the card.

Using CNC milling is very precise. Such precision is necessary because it is intended that the "negative" milled onto the bottom surface of the upper protective layer 101 will leave the required stress relief volume around the electrical components 102, 107, 106 on the FPCBA 103. This avoids pressure on the sensitive electronics and protects them from compressive and shearing forces as the card is used and is bent as it is handled. Calculations are made that construct relief pockets around the electronics so that enough space exists between the components 102, 107, 106 and the material of the upper protective layer 101 that the card withstands the mandated testing of 250 bendings of the card in each of the four possible orientations (i.e 1 ,000 bendings in total) without chip failure or visible cracking of the card.

It will be appreciated that various modifications and alternative

implementations exist that remain within the scope of the claims. For example, the required shape for the upper protective layer 101 may vary from that shown in the Figures depending on the nature of the electronic circuit and the components held thereon. The shape of the upper protective layer 101 may also be formed using alternative techniques to the CNC milling mentioned above. Any manufacturing technique providing suitable accuracy (e.g. to produce indents with accuracy to within 1 or 2 pm) can be used.