ELECTRONICALLY FUNCTIONAL YARNS

Abstract

An electronically functional yarn comprises a plurality of carrier fibres (6) forming a core with a series of electronic devices (2) mounted on the core with conductive interconnects (8) extending along the core. A plurality of packing fibres (10) are disposed around the core, the devices and the interconnects, and a retaining sleeve (12) is disposed around the packing fibres. The core, the devices and the interconnects are confined within the plurality of packing fibres retained in the sleeve. In the manufacture of the yarn the electronic devices with interconnects coupled thereto in sequence are mounted on the core; the carrier fibres with the mounted devices and interconnects are fed centrally through a channel with packing fibres around the sides thereof to form a fibre assembly around the core, which is fed into a sleeve forming unit in which a sleeve is formed around the assembly to form the composite yarn.

Claims

1. An electronically functional yarn having a yarn axis and comprising a plurality of carrier fibres forming a core; a series of electronic devices mounted on the core with conductive interconnects extending along the core; a plurality of packing fibres around the core, the electronic devices and the conductive interconnects; which packing fibres extend generally parallel to the yarn axis to preserve a substantially uniform cross-section along the length of the yarn and between the devices; and a retaining sleeve around the packing fibres, wherein the core, the electronic devices and the conductive interconnects are confined within the plurality of packing fibres retained in the sleeve.

2. An electronically functional yarn according to claim 1 wherein the carrier fibres are arranged in a substantially planar array.

3. (canceled)

4. An electronically functional yarn according to claim 1 wherein each of the electronic devices is mounted on at least two carrier fibres.

5. An electronically functional yarn according to claim 1 wherein the packing fibres are independent from one another.

6. An electronically functional yarn according to claim 1 wherein at least some of the packing fibres are bonded together.

7-8. (canceled)

9. An electronically functional yarn according to claim 1 wherein at least one of the conductive interconnects comprise at least one conductor extending the length of the yarn.

10-11. (canceled)

12. An electronically functional yarn according to claim 1 wherein the packing fibres fill spaces between the electronic devices.

13. An electronically functional yarn according to claim 1 including a filler material located in spaces between the electronic devices and within the packing fibres.

14. An electronically functional yarn according to claim 1 wherein the retaining sleeve is a fibre structure.

15. An electronically functional yarn according to claim 1 wherein the retaining sleeve comprises a supplementary yarn helically wound around the packing fibres.

16. An electronically functional yarn according to claim 1 wherein the retaining sleeve comprises an interlaced fibre structure.

17. An electronically functional yarn according to claim 1 wherein the retaining sleeve comprises an interlooped knitted fibre structure.

18. A method of manufacturing a composite yarn incorporating electronic devices comprising: forming a first subassembly by mounting electronic devices with interconnects coupled thereto in sequence on a core consisting of a plurality of carrier fibres; forming a fiber assembly around the core by feeding the first subassembly through a channel having a channel axis, and positioning packing fibres so the packing fibres extend generally parallel to the channel axis around the sides thereof, the packing fibres preserving a substantially uniform cross-section along the length of the fibre assembly; feeding the first subassembly and fibre assembly together into a sleeve forming unit in which a sleeve is formed around the fiber assembly to form a composite yarn; and withdrawing the composite yarn from the sleeve forming unit.

19. A method according to claim 18 wherein the channel is formed centrally in a disc having a periphery and peripheral openings around the periphery of the disk; and wherein sleeve fibres are fed through the peripheral openings to the sleeve forming unit in which they are processed to form the sleeve.

20. A method according to claim 18 wherein the channel extends into the sleeve forming unit.

21. A method according to claim 18 wherein the carrier fibres are arranged in a substantially planar array.

22. (canceled)

23. A method according to claim 18 wherein each of the electronic devices is mounted on at least two carrier fibres.

24. A method according to claim 18 wherein the sleeve forming unit comprises a braiding head.

25. A method according to claim 18 wherein the sleeve forming unit comprises a circular weft knitting head.

26. A method according to claim 18 wherein the sleeve forming unit comprises a circular warp knitting head.

27. A method according to claim 18 wherein the packing fibres are bunched or twisted between the electronic devices as the fibre assembly passes from the channel to the sleeve forming unit.

28. A method according to claim 18 wherein a filler is injected into the fibre assembly between the electronic devices as the fibre assembly passes from the channel to the sleeve forming unit.

29. A functional yarn according to claim 1 wherein the packing fibres are selectively arranged to fill spaces between the electronic devices.

30. An electronically functional yarn having a yarn axis and comprising a plurality of carrier fibres forming a core; a series of electronic devices each mounted on at least two of said carrier fibres with conductive interconnects extending along the core; a plurality of packing fibres extending around the core, the electronic devices and the interconnects, said packing fibres extend generally parallel to the yarn axis and selectively arranged to preserve a substantially uniform cross-section along the length of the yarn and between the electronic devices; and a retaining sleeve around the packing fibres, wherein the core, the electronic devices and the conductive interconnects are confined within the plurality of packing fibres retained in the sleeve.

31. An electronically functional yarn according to claim 30 including a filler material in the spaces between the electronic devices within the packing fibres.

32. An electronically functional yarn according to claim 30 wherein the carrier fibres are arranged in a substantially planar array.

Description

[0010] The invention will now be described by way of example and with reference to the accompanying schematic drawings wherein:

[0011] FIG. 1 shows a broken perspective view of a yarn according to a first embodiment of the invention;

[0012] FIG. 2 shows the sequence of stages in the manufacture of a yarn according to the invention;

[0013] FIG. 3 is a longitudinal sectional view of a yarn according to a second embodiment of the invention;

[0014] FIG. 4 is a lateral cross sectional view of the yarn of FIG. 3;

[0015] FIG. 5 illustrates a procedure for mounting electronic devices and conductive interconnects on carrier fibres in the manufacture of a yarn according to the invention; and

[0016] FIG. 6 shows the sequence of stages in an alternative procedure in the manufacture of a yarn according to the invention.

[0017] In the yarn shown in FIG. 1 a semiconductor chip 2 is sealed in a polymeric micro-pod 4 which extends around four 100 μm PBI carrier fibres 6. The chip shown is 900 μm long and has a square cross section of 500×500 μm. Two 150μm copper filament interconnects 8 extend from the chip 2 within the pod 4 over the carrier fibres 6. Polyester packing fibres 10 (diameter 10 μm) extend around the pod 4, the carrier fibres 6, and the interconnects 8. As shown they extend substantially parallel to the yarn axis, but may be bunched or twisted to fill the spaces between the pods 4. A filler (not shown) may also be used for this purpose. Some twisting of the packing fibres around the pods 4 can also be of value to provide a protective layer, but this will depend upon the shape of the pod. The linear arrangement of packing fibres shown can be more appropriate when the pod 4 is rectanguloid or cylindrical in shape. Whatever arrangement is selected some of the packing fibres 10 can be bonded together by adhesive or heating to provide an hermetic seal around the pod. An hermetic seal can also be established by sandwiching the devices, their interconnects and the carrier fibres between two normally ultra-thin polymeric films. Bonding of at least some of the outer packing fibres is avoided, thereby allowing relative movement to accommodate bending or twisting of the yarn with minimum affect on the uniformity of the yarn as a whole.

[0018] A sleeve 12 surrounds the packing fibres 10 to stabilize the fibre assembly with the pods 4 and interconnects 8 held centrally therein, and particularly to provide additional protection of the interconnects from exposure and mechanical stress during use. Thus, fabrics including yarns according to the invention can survive washing and tumble drying for example, in addition to normal wear and tear during use, with less risk of compromise to the interconnects and the functionality of the chips or other devices installed in the yarn. The sleeve shown comprises a separate textile yarn 14 helically wound around the packing fibres 10. Alternative forms of sleeve are woven or knitted braids. A wide variety of fibres can be used for the sleeve, as noted above, which is normally a textile structure with fibres of diameter in the range 10-50μm.

[0019] A process for manufacturing a yarn of the invention is illustrated in FIG. 2. Carrier fibres 6 populated with electronic devices (pods 4 not shown in FIG. 2) such as semiconductor chips are delivered round a guide pulley 16 to a central channel 18 in a disc 20. Packing fibres 10 are delivered round guide pulleys 22 also to the channel 18 on opposite sides of the carrier fibres 6. More than two delivery paths for the packing fibres 10 can be made if desired if a more dense or diverse layer of fibres is required around the carrier fibres 6 in the manufactured yarn. If a filler is to be inserted between the pods (4) this can be injected at this stage. Any adhesive or heat treatment of the packing fibres 10 is also applied at this stage.

[0020] The assembly comprising the carrier (6) and packing (10) fibres passes from the channel 18 to a sleeve unit 24. In the process shown in FIG. 2 the sleeve comprises separate textile yarns 26 delivered through openings in the periphery of the disc 20 which are knitted, woven or braided in the sleeve unit 24. Any twisting or bunching of the packing fibres 10 is carried out as the assembly passes from the channel 18 to the sleeve unit 24. The completed yarn emerges from the sleeve unit as shown, normally by being drawn at an appropriate rate.

[0021] FIGS. 3 and 4 illustrate a second embodiment of the invention in which the interconnects 30 extend over the electronic devices 32 on the opposite side from the core 34 comprising the carrier fibres, and into the core from either side of each device. Each device is typically a semiconductor packaged die 36 attached to the core 34 by a layer 38 of adhesive on one side with copper interconnects 30 soldered thereto on the other side. The device 36 and the attached sections of the core 34 and the interconnects 30 are enclosed in a polymeric resin micro-pod 42. Alternatively or additionally, the devices, interconnect and carrier fibres can be hermetically sealed between two ultra-thin polymeric films. The packing fibres 40 that are shown in a relatively regular formation in FIG. 4, are mobile and can be twisted and/or bunched as shown in FIG. 3 around and between the micro-pods to preserve a substantially uniform cross section for the completed composite yarn. A filler can also be used for this purpose if required. A textile sleeve comprising fibres 44 surrounds the packing fibres.

[0022] FIG. 5 illustrates how each electronic 32 devices may be mounted on the core 34 in a yarn of the kind shown in FIGS. 3 and 4. A layer 38 of adhesive is applied to one or more carrier fibres in the core 34; the device 32 bearing solder pads 46 is mounted on the adhesive layer 38, and the adhesive bond is cured by ultraviolet spot curing. Copper wire 48 is laid on the solder pads 46; solder paste 50 is applied and the joints are secured by infra-red reflow soldering. The copper wire is then cut as required to create individual interconnects, or left if it is to bypass one or more adjacent devices. The device and attached sections of the wire 48 and core 34 are then enclosed in a resin set by ultraviolet spot curing to form the micro-pod 42.

[0023] The manufacturing process shown in FIG. 6 illustrates particularly an alternative technique for installing the packing fibres and creating the sleeve. The core 34 carrying the devices 32 in their micro-pods 42 and interconnects, is fed centrally around a first guide roller 52 to a central opening in a disc 54. Sleeve fibres 56 and packing fibres 58 are fed from respective second and third guide rollers 60 to alternate openings 62 and 64 around the periphery of the disc 54. From the disc 54 the packing fibres 58 are fed to a central duct 66 which also receives the core 34 carrying the devices and micro-pods. The sleeve fibres 56 pass through a stationary yarn guide tube 68, and then though a rotatable cylindrical yarn guide 70 to a needle cylinder 72 where the fibres are interlooped to form the sleeve. The completed composite yarn is drawn from the needle cylinder 72 at a rate commensurate with the knitting process. The same materials as are referred to above can be used for the carrier fibres; the packing fibres, and the sleeve fibres, in the process of FIG. 6

[0024] The central duct 66 has a shaped conical opening for receiving the packing fibres, to ensure they are arranged around the core 34 and its micropods and interconnects. The duct 66 extends the full length of the yarn guide tube 68 and rotatable cylindrical yarn guide 70 to retain the packing fibres within the sleeve fibres as they are positioned to be knitted into the sleeve in the needle cylinder 72. Thus, in the completed yarn, the packing fibres within the sleeve surround and enclose the carrier fibres, micropods and interconnects ensuring that the interconnects extend along the core. The process illustrated would use a warp knitting process in which the cylindrical yarn guide 70 oscillates to properly orient the sleeve fibres prior to knitting. The process can be adapted for weft knitting, but the orientation of the fibres around the duct 64 prior to knitting is more complex.