METHOD OF ACHIEVING A FUNCTIONAL ELECTRONIC TEXTILE

Abstract

An encapsulated assembly of electronic componentry, suitable for incorporation into a textile or a yarn, and the assembly comprising two flexible substrates (3, 4) which encapsulate the electronic componentry, at least one of the flexible substrates comprising at least one preformed relief region (3a), which provides a volume which at least in part accommodates the electronic componentry, and the componentry located substantially at a neutral axis (N) of the assembly.

Claims

1. An encapsulated assembly of electronic componentry, suitable for incorporation into a textile or a yarn, and the assembly comprising two flexible substrates which encapsulate the electronic componentry, at least one of the flexible substrates comprising at least one relief region configured to define a volume which at least in part accommodates the electronic componentry, said relief region being flexible to define said volume by conformal relief when applied to encapsulate the componentry, and the componentry located substantially at a neutral axis of the assembly.

2. An assembly as claimed in claim 1 in which the at least one substrate comprises a transitional portion which connects the relief region to a surrounding part of said flexible substrate.

3. An assembly as claimed in claim 2 in which the transitional region forms a side wall of the relief region.

4. An assembly as claimed in claim 2 in which the transitional portion has a curved shape when viewed in cross-section.

5. An assembly as claimed in claim 1, in which the electronic componentry comprises at least one of a semiconductor die and an electronic component.

6. An assembly as claimed in claim 1, in which at least one of the flexible substrates comprises electrically conductive tracks and/or conductive pads.

7. An assembly as claimed in claim 1, in which a filler or adhesive is provided in said relief region.

8. An assembly as claimed in claim 7 in which the filler or adhesive comprises a flexible material.

9. An assembly as claimed in claim 1 in which the electronic componentry is arranged to at least one of provide an output, receive an input and process at least one of data and signals.

10. An assembly as claimed in claim 1 in which the electronic componentry comprises at least one of an integrated circuit, a battery, an antenna, an energy harvester, a connector, a sensor and an actuator.

11. An assembly as claimed in claim 1 in which at least one of the flexible substrates comprises one or more of conductive interconnects, bond pads, solder bumps and adhesive.

12. (canceled)

13. (canceled)

14. A method of manufacturing an encapsulated electronic componentry assembly, comprising the steps of: bringing together a first flexible substrate and a second flexible substrate, and in which electronic componentry is provided between the first flexible substrate and the second flexible substrate, at least one of the substrates being applied to encapsulate the componentry is such that it adopts a conformal relief when applied.

15. A method as claimed in claim 14 which comprises the step of applying at least one of the substrates by way of a vacuum application process.

16. A method as claimed in claim 14 in which at least one of the substrates comprises a an adhesive coated thermoplastic film, and is applied to the encapsulate the componentry by way of a vacuum application process.

17. A method as claimed in claim 16 which comprises heating the adhesive coated thermoplastic film such that it becomes soft and further comprising applying a vacuum that brings the film down over the componentry.

18. An assembly as claimed in claim 1 in which said relief region is flexible to define said volume by conformal relief.

19. A textile or yarn comprising an encapsulated assembly of electronic componentry further comprising two flexible substrates which encapsulate the electronic componentry, at least one of the flexible substrates comprising at least one relief region configured to define a volume which at least in part accommodates the electronic componentry, said relief region being flexible to define said volume by conformal relief, and the componentry located substantially at a neutral axis of the assembly.

20. A textile or yarn as claimed in claim 19 in which said relief region is flexible to define said volume by conformal relief.

21. The textile or yarn as claimed in claim 19 further comprising a carrier yarn.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Various embodiments of the invention will now be described, by way of example only, in which:

[0049] FIG. 1 is a cross section of an assembly comprising encapsulated electronic componentry,

[0050] FIG. 2 is an exploded perspective view of the assembly of FIG. 1, which shows various components of the assembly of FIG. 1,

[0051] FIG. 3 is an extended cross-sectional view of the assembly shown in FIG. 1,

[0052] FIG. 4 shows a second embodiment of the invention, and

[0053] FIG. 5 shows a third embodiment of the invention.

DETAILED DESCRIPTION

[0054] There are now described various embodiments of encapsulated electronic componentry which are adapted to be incorporated into a yarn, or into a textile. This advantageously allows the creation of a functional fabric, various applications of which are described below. Like reference numerals are used to denote the same or substantially the same features, where appropriate for different embodiments.

[0055] With reference initially to FIG. 1, there is shown an encapsulated electronic assembly 1. The assembly comprises a first flexible substrate 3, and a second flexible substrate 4. The first flexible substrate 1 comprises a preformed region 3a. This provides a relief or raised formation in the form of a protrusion or boss. This defines an internal volume which serves to at least in part accommodate the electronic componentry 10.

[0056] As can be seen from FIG. 1, the substrate 3 comprises a transitional region 3b, which serves to define the height or upstand of the region 3a, from the ‘lower’ or basal portion 3c of the first substrate 3. The transitional region includes a curved cross-sectional profile. This serves to reduce or minimise any the effect of any damaging or structurally detrimental bending forces experienced at those regions which could result in mechanical failure. Sharp corners can act as stress raisers concentrating the stress, whereas curved junctions avoid this and allow for a more even stress distribution.

[0057] The substrate 3 is formed of a flexible polymer material, such as Kapton®.

[0058] The electronic componentry 10 comprises a semiconductor die, such as a bare silicon die, having a thickness of around 250 μm. The electronic componentry may provide different functionalities, some of which are listed below.

[0059] The second flexible substrate 4 is, in contrast to the first flexible substrate, substantially planar, and is of the same material as the first flexible substrate. The second flexible substrate is provided with conductive tracks and bumping pads, shown generally by reference numeral 8. These are connected to the silicon die 10 by way of portions of conductive adhesive/soldering paste 9. At the end of each flexible substrate there could be provided a connector to allow a mechanical and electrical attachment to external electronics.

[0060] The assembly 1 further comprises an upper layer 6a of adhesive or filler, and a lower layer 6b of a flexible adhesive or filler. These are provided during fabrication of the assembly 1, and serve to internally encapsulate the electronic componentry. The fabrication process of the assembly is described in more detail below.

[0061] As can be seen in FIG. 3. The first substrate 3 is located atop the second substrate 4.

[0062] Highly advantageously, the electronic componentry 10 provided by the silicon die is located on a neutral bending axis. This results in the componentry 10 being subjected to significantly reduced or minimised bending forces, which occur when the yarn to which the encapsulated assembly is incorporated is bent or twisted in use, such as during a wash cycle, where for example the yarn is part of a wearable garment. The adhesive/filler layers 6a and 6b, ensure that the componentry is located and maintained at the neutral axis, and the thicknesses of those layers are chosen accordingly.

[0063] One application of the above embodiment is an (invisible) Radio Frequency Identification (RFID) tag. RFID is a technology that incorporates the use of electromagnetic coupling in the radio frequency (RF) band to identify an object. RFID allows tagging of assets, inventory, personnel and patients with a tiny electronic tag.

[0064] The packaging approach described above can combine with a bespoke antenna design to achieve a thin RFID filament that can be woven into a textile or incorporated into a yarn. As such, this RFID tag can be placed invisibly into a textile RFID tags and can be used in numerous contexts, including:

[0065] Tracking textile products, providing quality control and facilitating end of life recycling and re-use of textiles. This allows for a high specificity of textile sorting which means that the waste stream can be processed to achieve best value.

[0066] Monitoring wearer's safety, such as tracking and recording of safety PPE or other relative products at a construction site, tracking medical items/equipment at hospitals, for security.

[0067] Tracking workflow, such as tracking patients and new born babies in hospital or tracking employees at a special working environment.

[0068] Providing security access control as an alternative to the access card.

[0069] Garment washing and laundering. Invisible tags allow laundry owners to optimise workflows, ensure adequate stock levels, and reduce inventory losses.

[0070] Tracking high-turnover products, like clothing.

[0071] Protecting high-end brands and improving anti-counterfeit measure. Fake luxury goods are a major problem for companies the world over. High end products like

[0072] Chanel bags can be embedded with a unique RFID tag, which customers can scan in-store to provide authentication as well as provides an alternative store security measure to conventional pin-in security tags which are likely to damage the clothing.

[0073] Improving the brand loyalty by enhancing customer experience in store, such as real time stock availability check (e.g. click and collect), allowing retailers to recognise a customer as he/she walks into the store, offering speed check-out and automatic shopping.

[0074] Invisible tracking of prison inmates.

[0075] In addition to the application to RFID, the invention also finds application in smart fabrics generally since the invention provides for smart fabrics with high durability. Durability is a key issue holding back the commercial deployment of smart fabrics. Smart fabrics have application in the military, healthcare, sports and fitness, consumer markets and creative and cultural industries applications. Typical applications include:

[0076] Sleep activity monitoring via accelerometers in bedding.

[0077] Activity monitoring via accelerometers in clothing for fitness.

[0078] Activity monitoring via accelerometers for proof of wellbeing (e.g. military, coal miners).

[0079] Activity monitoring via accelerometers for communication of information via gestures.

[0080] LED display on clothing for visibility for example when cycling.

[0081] LED display on clothing/bags for decoration in fashion applications.

[0082] Integration of sensors in a smart bra to improve posture support and breathing.

[0083] Sofas/carpet/upholstery with periodic lighting via LEDs. These applications would not require washing but would benefit from the improved durability offered by the invention.

[0084] Lighting strips in mobile phone case.

[0085] Moisture detection in underwear via humidity sensors.

[0086] Interactive clothing for fashion/consumer applications.

[0087] Conductive yarns and LEDs for automotive head liners.

[0088] Water level monitoring in hydration bladder in back pack.

[0089] LED and sensing in motorcycle jacket/helmet.

[0090] Reference is made to FIG. 4 which shows a second embodiment of the invention which comprises two flexible substrates 13 and 14, which are both preformed with a relief region, 13a and 14a, and which are brought together to encapsulate electronic componentry. The componentry 10 is located on a neutral bending plane N.

[0091] Reference is made to FIG. 5, which shows a further embodiment in which multiple encapsulated assemblies are incorporated into a yarn. In FIG. 5, multiple encapsulated assemblies (or pods) are distributed along part of the length of the yarn. It will be appreciated that the second flexible substrate is provided as a long, single strip which extends along the respective length. The second substrate 4 is provided on a carrier yarn 21, which may comprise Zylon fibres. Packing fibres 22 are also provided which sandwich the carrier yarn 21 and the encapsulated assemblies therebetween. Externally of the packing fibres and the carrier and the encapsulated assemblies, there is provided covering fibres (which may comprise one or more of PE, PA, Wool, Cotton, Silk). This arrangement results in the encapsulated assemblies being substantially centrally located within the yarn.

[0092] The process used in the manufacture of the assembly is as follows. Firstly, the electronic component is attached with solder or adhesive to the substrate which contains conductive tracks. The gap below the component and the flexible substrate is filled (under-filling) with flexible material which is other than solder. Finally, the relief region which does not house the component is entirely or partially filled with another or the same flexible material which conveniently also acts as the adhesive to attach the two flexible substrates together. The same material is also applied to the rest of one or both of the flexible substrates. The flexible substrates are then placed in a vacuum to remove bubbles, which may be for up to around an hour. The entire assembly is then placed in an oven to cure the adhesive filling.

[0093] It will be appreciated that the thicknesses and stiffnesses of all the materials (solder/adhesive, under-fill, relief fill (6a and 6b)) can be selected to adjust the position of the neutral axis to ensure the electronic component is situated in the neutral axis of the assembly. The position of the neutral axis may be further adjusted by having different thicknesses, and differing materials, of flexible substrate.

[0094] In another embodiment, in place of the use of a substrate with a pre-formed relief, a vacuum application process is used to apply a layer which is located atop the componentry. This potentially simplifies the overall manufacturing process in that it is not required to produce a substrate which has a preformed relief, such as the first flexible substrate 3 described above. One such method for realising the package assembly using a vacuum forming process uses an adhesive coated thermoplastic film. The film is heated such that it becomes soft and a vacuum applied that brings the film down over the circuit where the adhesive bonds the film to the circuit substrate and components. Once applied, the topology/relief of the film then substantially conforms to the substrate/componentry. The position of the neutral axis can be maintained at the surface of the circuit by using the appropriate thermoplastic film thickness which can be calculated using known equations (see below) and given the Young's modulus of the substrate material and the thermoplastic film. The relevant equation may be expressed as:

[00001]$\stackrel{\_}{y}=\frac{{.Math.}_{i=1}^n{E}_i{x}_i{h}_i\left(2{.Math.}_{j=1}^i{h}_j-h_i\right)}{2{.Math.}_{i=1}^n{E}_i{x}_i{h}_i}$

[0095] Where E.sub.i, x.sub.i and h.sub.i represent the elastic modulus, width and thickness of the layer of the assembly where i=1 is the circuit substrate and i=2 is the top encapsulating film respectively. “n” is the total number of layers and y is the neutral axis position.