WO2004048691A2

WO2004048691A2 - Method of manufacturing a fibrous substrate incorporating an electronic chip

Info

Publication number: WO2004048691A2
Application number: PCT/GB2003/005092
Authority: WO
Inventors: Paul Howland; Peter Mclean Henderson; James Peter Snelling
Original assignee: De La Rue International Limited
Priority date: 2002-11-28
Filing date: 2003-11-24
Publication date: 2004-06-10
Also published as: GB2395724A; GB0227773D0; AU2003285510A1; WO2004048691A3; GB2395724B

Abstract

The invention relates to improvements in manufacturing substrates and in particular to a method of manufacturing a fibrous substrate, such as paper, incorporating an electronic circuit. A method of making a fibrous substrate comprises the steps of depositing fibres on a support surface to form a fibrous mat and incorporating at least one electronic chip (11) during the fibre deposition process. The support surface comprises means for modifying the distribution of fibres as they are deposited on the support surface to provide at least one area (13, 14) of the fibrous mat having a grammage which is greater or less than that of the rest of the fibrous mat. The said area (13, 14) is positioned with respect to said chip such that the thickness of the substrate in a region of the chip is not greater than the thickness of the substrate in a region of the substrate immediately adjacent the chip.

Description

METHOD OP MANUFACTURING A FIBROUS SUBSTRATE INCORPORATING AN ELECTRONIC CHIP

The invention relates to improvements in manufacturing substrates and in particular to a method of manufacturing a fibrous substrate, such as paper, incorporating an electronic circuit.

It is generally known to include in security paper, and other security substrates, a variety of security features which render the imitation of documents produced therefrom more difficult. These security features also usually assist in the verification of the documents either by altering the view of the documents under different conditions or by providing visually or machine readable properties.

It has become desirous to incorporate electronic chips, such as IC or RFID chips, into substrates, for security and authentication purposes and these provide a highly versatile security feature which is difficult to counterfeit. Some examples of known security substrates incorporating such chips are described below.

WO-A-0007151 describes an electronic switching circuit embedded in security paper. A carrier freguency input signal is transmitted to the switching circuit for checking authenticity and the circuit emits an output signal representing the authenticity feature in response to the received input signal.

DE-A-19601358 similarly describes a base substrate incorporating an integrated circuit, which is non-detachably and wholly embedded within the substrate. The circuit can be read without contact by the reading device. The circuit can be read capacitively, inductively or by light.

O-A-0065545 describes a security feature for use in substrates, such as paper, which comprises a plastic support provided with two or more space apart conducting areas which are electrically interconnected by means of a diode connection.

WO-A-0202350 also describes security paper which has a security element which is at least partially exposed on one surface of the paper and which provides at least one visually verifiable optical effect and incorporates an integrated circuit.

US-A-6417075 describes a method of producing very thin semiconductor wafers formed from a plurality of very thin substrate layers. This is achieved by etching the silicone away from the back of the wafer stack to the desired thickness of the layer.

However, problems arise in the incorporation of such chips in a fibrous substrate, such as paper, due to their bulk. Currently the chips are incorporated by laminating them between to plies of papers. However, such chips typically have a height of 40 microns. When these are embedded into security paper, which typically has a thickness of 190 microns, this results in an increase in the thickness in the area of the chips of 20%. This creates two particular problems. Firstly, the smoothness of the surface of the security paper is critical for achieving good printing. The lumpiness of paper containing chips makes printing very difficult. Secondly, where security paper is calendered during the paper making process, the calender rolls are damaged by the hard chips embedded within the paper and this results in continuous scoring of the rolls which therefore need to be replaced frequently at great expense. The problems are further exacerbated where the chips are mounted on security threads or elements, as in WO-A- 0202350, as such security elements commonly have a thickness of 30 microns. Thus in the areas of the chips the thickness of the paper increases from, say 190 microns to 260 microns. Furthermore, it should be noted that the chips themselves are vulnerable to damage during the processing due to calendering pressures. Obviously any damage to the chips can render them useless and needs to be avoided.

The invention therefore relates to a method of manufacturing fibrous substrates, such as paper, incorporating an electronic circuit which reduces or eliminates the problems caused by the additional bulk of the chip and any carrier associated therewith.

The invention therefore provides A method of making a fibrous substrate comprising the steps of depositing fibres on a support surface to form a fibrous mat and incorporating at least one electronic chip during the fibre deposition process, in which the support surface comprises means for modifying the distribution of fibres as they are deposited on the support surface to provide at least one area of the fibrous mat having a grammage which is greater or less than that of the rest of the fibrous mat, said at least one area being positioned with respect to at least one said chip such that the thickness of the substrate in a region of the at least one chip is less than the thickness of the substrate in a region of the substrate immediately adjacent the at least one chips.

The method of the present invention is therefore significantly advantageous over the incorporation of chips by a lamination process as a result of the bulk of fibres being displaced to either side of the chips and reducing the thickness increase associated with the chip.

A lamination process, on the other-hand, results in the thickness over the chip area being the aggregate thickness of the substrate, chip and any chip carrier, ie an elongate thread.

The invention will now be described, by way of example only, with reference to the accompanying drawings in which:-

Figure 1 is a cross-sectional end elevation of a security document made from a substrate according to the present invention in which an electronic chip is wholly embedded;

Figure 2 is a plan view of a security document made from paper made according to the present invention with an electronic chip exposed at one surface thereof;

Figure 3 is a cross-sectional end elevation of the security document of Figure 2 on the line II- II;

Figure 4 is a cross-sectional end elevation of an alternative security document to that shown in Figure 2 in which the electronic chip is revealed in windows on both sides of the document;

Figure 5 is a cross-sectional end elevation of yet another alternative security document also with the electronic chip wholly embedded; and

Figure 6 is a cross-sectional end elevation of yet a further alternative security document with the electronic chip exposed in one surface of the security document.

Fibrous substrates, such as paper, can be made according to the present invention, using known paper making machines such as cylinder mould or Fourdrinier machines. Essentially the machine used must have a support surface on which fibres are deposited which can be manipulated so as to vary the distribution of fibres in a suitable manner to accommodate chips.

Although not limited to a cylinder mould process, the invention will be described below with reference to such process. Cylinder mould machines are commonly used in paper making and the basic process consists of rotating a mould cover partially immersed in a vat of aqueous fibrous stock. Fibres are deposited on the surface of the mould cover as water drains through to form a fibrous mat. This mat, which forms the basis of the paper, is couched from the cylinder mould cover and transferred to other processing elements of the machine, during which further water is extracted from the mat/paper as it passes through various drying stages of the machine.

In one embodiment of the invention, an electronic chip 11 is incorporated within a fibrous substrate, such as paper, so that it is wholly embedded within the paper. This is illustrated in Figure 1, which shows a cross sectional side elevation of a security document 10 made from paper according to this method. The electronic chip 11, which may be an IC, RFID or any other form of electronic chip, may be mounted on an elongate element or thread 12. The thread 12 is preferably made from a non-conducting polyester material .

The support surface of the apparatus used in the method of the present invention is provided with means for varying the fibre distribution on the support surface. These means can either be traditional embossed regions or drainage limitation means, such as electrotype. In the latter case, the electrotype restricts drainage of the fibre suspension through the forming wire, thereby creating a lower grammage region. Such modifications are well known in paper making to form watermarks or windows in paper. In the present invention the means for varying the fibre distribution are designed to provide regions of different grammages in the fibrous substrate to accommodate the electronic device.

For situations where direct contact with the chips is not necessary, the embossed or electrotyped regions can be modified such that the drainage limitation through the cylinder mould cover in these regions is not so extreme as is required for the production of windows. In the embodiment of the invention shown in Figure 1 they are used to limit not prevent, water drainage, and therefore fibre deposition, to provide regions of lower grammages of the substrate above and below the electronic chips 11. The thread 12 bearing the chips 11 is brought into contact with the cylinder mould below the surface of fibrous stock, so that a first layer of fibres has already been deposited on the support surface. The chips 11 are positioned over the regions of lower grammages. As a result the chips 11 are wholly embedded within the substrate, but are covered on either side with layers 13 of fibrous substrate which are significantly thinner (i.e. of reduced grammage) than the substrate away from the chips 11.

For some applications, it is desired to have access to the chips 11 at one or both surfaces of the paper as shown in figures 2, 3 and 4. In these examples, the chips 11 are mounted on thread 12 in such a manner that they are accessible from both sides of thread 12. This means that the thread 12 does not need to be oriented within the fibrous substrate. The drainage limitation means/embossings are modified to create one or more windows in one or both surfaces of the substrate in registration with the electronic chips 11. The thread 12 is brought into contact with the drainage limitation means/embossing before being introduced into the fibrous stock.

The resulting windows means that the chips can be accessed directly by appropriate reading means and can be directly contacted thereby. Where windows are produced on both sides of the fibrous substrate in registration with the chips 11, as shown in Figure 4, this means that the chips 11 can be accessed from either side of the substrate.

In all three examples the lesser bulk of substrate above and/or below the chip 13 as compared to the thickness of the bulk of the substrate means that the overall surface of the substrate is smoother, which provides for better printing and less damage to the calender rolls. Furthermore the chip 13 itself is provided with protection by the additional thickness of substrate surrounding the chip 13.

In a further embodiment of the invention, as shown in Figure 5, embossings on the support surface are used to make thicker regions 14 (of greater grammage) of the substrate on either side of the chip 11. The support surface, such as the cylinder mould forming wire, is embossed in the pattern required. Valleys of the embossings, as seen from the forming side of the wire mesh become the thicker higher grammage regions 14. The chips 11 can then be applied, as free chips located in the valley between two thicker regions 14. These thicker regions 14 of the substrates help to protect the chip 11 and calender rolls as they ride over the softer substrate regions 14 and do not bear down on the harder chips 11. It can thus be seen that the chips 11 can be incorporated with the substrate either as a free chip or mounted on an elongate element or thread 12. Chips mounted on the threads 12 can be mounted on one or both sides or can be partially embedded into the thread.

The regions of reduced or increased thickness 13,14 can be provided in a continuous or discontinuous manner in the machine direction. To achieve this the drainage limitations means need to be profiled in an appropriate manner.

In a further embodiment of the invention, as illustrated in Figure 6, chips 11 are used which are applied to or partially embedded in one surface of the thread 12 only. This means that the thread 12 must be oriented as it is brought into contact with the cylinder mould cover with the chip facing outwards, away from the mould cover. Although this creates more difficulties in processing the chips 11 can be thinner, and this is advantageous in the terms of the thickness of the end product.

In this embodiment the solid chip 11 acts as the drainage limitations means in the same way as an electrotype and the fibres flow around it in the same way as they do around electrotype. The resulting layer of substrate 15 overlying the chip 11 is thinner than in the surrounding regions, which helps to obviate the disadvantages highlighted previously.

It should also be noted that the chip 11 may also be placed over a drainage limiting area to reduce the thickness of the paper, chip and thread in that area.

This method of manufacturing fibrous substrates incorporating electronic circuits 11 is highly advantageous for a number of regions. In addition to solving the problems described above, the regions 13,14,15 of reduced or increased thicknesses (grammages) provide a watermark effect. This watermark effect can be enhanced to provide watermark patterns, if desired, which further contribute to the security of documents made from such paper. Whether enhanced or not, the areas of increased thickness 14 will be darker than the rest of the substrate when viewed in transmission. The areas of reduced thickness 13 will be lighter than the rest of the substrate when viewed in transmitted light although where they coincide with the chip 11, this effect will be disrupted by the presence of the chip itself which will appear darker in transmission. However, the watermark effect can be designed to use the presence of the chip 11 as part of the pattern of the watermark.

The method according to the present invention may also be used in a twin ply lamination process as described in EP-A-0860298 where one ply is manufactured as described above incorporating a chip and then laminated to another ply, either of paper or the like. The second sheet may be brought into contact with the first sheet either during the paper making process, as in EP-A-0860298 or post production.

It should also be noted that the threads 12 may be metallised to provide conductive antenna, which also provides darker regions in transmitted light.

Fibrous substrates made according to the aforegoing method can be used to make security documents such as banknotes, passports, vouchers, certificates, security bonds, security labels, telephone cards, smart cards, bank cards or the like.

Claims

CLAIMS : -

1. A method of making a fibrous substrate comprising the steps of depositing fibres on a support surface to form a fibrous mat and incorporating at least one electronic chip (11) during the fibre deposition process, in which the support surface comprises means for modifying the distribution of fibres as they are deposited on the support surface to provide at least one area (13, 14) of the fibrous mat having a grammage which is greater or less than that of the rest of the fibrous mat, said at least one area (13, 14) being positioned with respect to at least one said chip (11) such that the thickness of the substrate in a region of the at least one chip (11) is not greater than the thickness of the substrate in a region of the substrate immediately adjacent the at least one chip (11) .

2. A method as claimed in Claim 1 in which the means for modifying the distribution of fibres comprise drainage limitation regions of the support surface.

3. A method as claimed in claim 1 or claim 2 in which the means for modifying the distribution of fibres comprise embossings of the support surface.

4. A method as claimed in any one of the preceding claims in which the means for modifying the distribution of fibres comprise raised areas of the support surface.

5. A method as claimed in any one of the proceeding claims in which the at least one electronic chip (11) is mounted on an elongate element (12) which is brought into contact with the support surface after fibres have first been deposited thereon.

6. A method as claimed in any one of claim 1 to 4 in which the electronic chip (11) is mounted on an elongate element (12) which is brought into contact with the support surface before fibres have first been deposited thereon.

7. A method as claimed in any one of the preceding claims in which the at least one electronic chip (11) is mounted on one side of an elongate element (12) and another side of the elongate element (12) is brought into contact with the support surface.

8. A method as claimed in any one of the preceding claims in which the support surface is the forming wire of a cylinder mould machine.

9. A method as claimed in any one of the preceding claims further comprising the step of laminating a second fibrous substrate to a first fibrous substrate, said first fibrous substrate incorporating at least one electronic chip (11) .

10. A fibrous substrate made according to the method of any one of the preceding claims in which at least one electronic chip (11) is wholly exposed in a window in one surface of substrate.

11. A fibrous substrate as claimed in claim 10 in which at least one electronic chip (11) is exposed in windows in both surfaces of the substrate.

12. A fibrous substrate made according to the method of any one of claims 1 to 9 in which the thickness of the substrate in the region (13) of the at least one electronic chip (11), is less than the thickness of the substrate in the region of the substrate adjacent the at least one electric chip (11) .

13. A fibrous substrate made according to the method of any one of claims 1 to 9 in which the thickness of the substrate in the region (14) immediately adjacent the at least one electronic chip (11) is greater than the thickness of the substrate in the region of the electronic chip (11) .

14. A fibrous substrate as claimed in any one of claims 10 to 13 in which a second fibrous substrate is laminated to a first fibrous substrate, said first fibrous substrate incorporating at least one electronic chip (11).

15. A fibrous substrate as claimed in any one of claims 10 to 14 in which the substrate is paper.

16. A security document made from the substrate according to any one of claims 10 to 14.

17. A security document as claimed in claim 16 in which the security document comprises a banknote, passport, voucher, certificate, security bond, telephone card, smart card, bank card, or the like.