Method of forming a coil module for an aerosol-generating system

Abstract

A method (100) of forming an inductor coil module (1) for an aerosol-generating device (21), wherein the method (100) comprises providing (101) a tubular frame (2) having an outer surface (3) and an inner surface (4), the inner surface (4) defining a cavity (5) for receiving an aerosol-forming substrate (25) when the inductor coil module (1) is in use in an aerosol-generating device (21). The method (100) further comprises contacting (105) the outer surface (3) of the tubular frame (2) with a plating solution (12) to plate a portion of the outer surface (3) with a metal. A laser beam (9) is directed onto the portion of the outer surface (3) of the tubular frame (2), the portion of the outer surface (3) of the tubular frame (2) being a helicoidal track (6) circumscribing the cavity (5). As such, the portion of the outer surface (3) of the tubular frame (5) plated with the metal forms a helical coil circumscribing the cavity (5). The metal helical coil may form an inductor coil (14) of the inductor coil module (1).

Description

[0001] METHOD OF FORMING A COIL MODULE FOR AN AEROSOL-GENERATING SYSTEM

[0002] The present disclosure relates to aerosol-generating systems in which an aerosol-forming substrate is heated by induction to generate an aerosol. In particular, the present disclosure relates to coil modules of aerosol-generating devices of such aerosol-generating systems and methods of forming coil modules.

[0003] Aerosol-generating systems in which an aerosol-forming substrate is heated by induction to generate an aerosol are known. In such systems, a susceptor and an inductor coil are typically provided. An alternating current is supplied to the inductor coil, causing the inductor coil to generate an alternating magnetic field. The susceptor is arranged in the alternating magnetic field, causing eddy currents to be generated in the susceptor, which cause the susceptor to heat up via one or both of resistive losses and hysteresis losses. Heat from the heated susceptor is transferred to the aerosolforming substrate, which releases volatile compounds that condense to form an aerosol.

[0004] In some aerosol-generating systems in which an aerosol-forming substrate is heated by induction, the inductor coil is wound on a frame to form a coil module. The frame may be a tubular frame having an inner surface defining a cavity for receiving aerosol-forming substrate. The inductor coil may be wound around the cavity such that the inductor coil circumscribes at least a portion of the cavity, on an outer surface of the tubular frame. In this arrangement, the alternating magnetic field generated by the inductor coil when an alternating current is supplied to the inductor coil passes through the cavity, such that a susceptor arranged in the cavity may be heated.

[0005] When forming a coil module for such an aerosol-generating system, the inductor coil is typically formed from a wire that is wound around the frame, which can be a challenging process to automate. It would be desirable to improve the method of forming a coil module for an aerosol-generating system.

[0006] According to the present disclosure, there is provided a method of forming an inductor coil module for an aerosol-generating device. The method may comprise providing a frame. The frame may be a tubular frame having an outer surface and an inner surface. The inner surface may define a cavity. The cavity may be for receiving an aerosol-forming substrate when the inductor coil module is in use in an aerosol-generating device. The method may further comprise contacting a surface of the frame with a plating solution to plate a portion of the outer surface with a metal. Where the frame is a tubular frame, the outer surface of the tubular frame may be contacted with the plating solution. A laser beam may be directed onto the portion of the surface of the frame. Where the frame is a tubular frame, the laser beam may be directed onto the portion of the outer surface of the tubular frame. The portion of the outer surface of the tubular frame may be a helicoidal track circumscribing the cavity.

[0007] According to the present disclosure, there is provided a method of forming an inductor coil module for an aerosol-generating device. The method comprises providing a tubular frame having an outer surface and an inner surface, the inner surface defining a cavity for receiving an aerosol-forming substrate when the inductor coil module is in use in an aerosol-generating device. The method further comprises contacting the outer surface of the tubular frame with a plating solution to plate a portion of the outer surface with a metal. A laser beam is directed onto the portion of the outer surface of the tubular frame, the portion of the outer surface of the tubular frame being a helicoidal track circumscribing the cavity. As such, the portion of the outer surface of the tubular frame plated with the metal forms a helical coil circumscribing the cavity. The metal helical coil may form an inductor coil of the inductor coil module.

[0008] The tubular frame may have a longitudinal axis. The helicoidal track may have a pitch that varies along the longitudinal axis of the tubular frame. The method may further comprise electrically connecting a flexible printed circuit to the plated helicoidal track.

[0009] According to the present disclosure, there is provided an inductor coil module for an aerosolgenerating device. The inductor coil module is formed by any of the methods described in this disclosure.

[0010] According to the present disclosure, there is provided an inductor coil module for an aerosolgenerating device. The inductor coil module comprises a tubular frame. The tubular frame may be formed from a polymeric material. The tubular frame may have an outer surface and an inner surface, the inner surface defining a cavity. The cavity may be for receiving an aerosol-forming substrate when the inductor coil module is in use in an aerosol-generating device. The inductor coil module may further comprise an inductor coil circumscribing the cavity. The inductor coil may be formed from a metallic helicoidal track deposited on a portion of the outer surface of the tubular frame.

[0011] According to the present disclosure, there is provided an inductor coil module for an aerosolgenerating device, the inductor coil module comprising: a tubular frame formed from a polymeric material, the tubular frame having an outer surface and an inner surface, the inner surface defining a cavity for receiving an aerosol-forming substrate when the inductor coil module is in use in an aerosolgenerating device; and an inductor coil circumscribing the cavity, the inductor coil being formed from a metallic helicoidal track deposited on a portion of the outer surface of the tubular frame.

[0012] The tubular frame may have a longitudinal axis. The helicoidal track may have a pitch that varies along the longitudinal axis of the tubular frame. A flexible printed circuit may be electrically connected to the helicoidal track.

[0013] According to the present disclosure, there is provided an aerosol-generating device comprising an inductor coil module. The inductor coil module is formed by any of the methods described in this disclosure.

[0014] As used herein, the terms “plate” and “plating” are used interchangeably with the terms “deposit” and “deposition”. Accordingly, the method comprises the step of contacting the outer surface of the tubular frame with a plating solution to plate or deposit a portion of the outer surface with a metal. The plating or deposition of the metal onto the portion of the outer surface of the tubular frame may be in the absence of the application of an electric potential. In other words, the plating or deposition of the metal onto the portion of the outer surface of the tubular frame may be electroless plating or electroless deposition. The plating or deposition may comprise electroplating or electrochemical deposition where the plating or deposition is performed in the presence of an applied electric potential.

[0015] The contacting the outer surface of the tubular frame with a plating solution to plate a portion of the outer surface with a metal may comprise contacting the outer surface of the tubular frame with a plating solution in the absence of an applied electric potential.

[0016] As used herein, an “aerosol-generating device” refers to a device that interacts with an aerosolforming substrate to generate an aerosol.

[0017] As used herein, an “aerosol-forming substrate” refers to a substrate capable of releasing volatile compounds upon heating to generate an aerosol. An aerosol-forming substrate may be part of an aerosol-generating article. For example, an aerosol-generating article may generate an aerosol that is directly inhalable into a user’s lung through the user's mouth. However in contrast to a conventional lit- end cigarette, the aerosol-forming article does not require combustion of the aerosol-forming substrate to generate an aerosol. An aerosol-forming article may be disposable. An aerosol-forming article may be, or may comprise, a tobacco stick.

[0018] As used herein, an “aerosol generating system” refers to a combination of an aerosol-generating device and one or more aerosol-forming articles for use with the device. An aerosol-generating system may include additional components, such as a charging unit for recharging an on-board electric power supply in an electrically operated or electric aerosol-generating device.

[0019] A challenge faced by the inventors in improving the method of forming the inductor coil module was that many methods of providing an electric circuit trace on the tubular frame, in the form of a coil, are not appropriate or possible. The tubular frame generally comprises non-metallic materials, and is typically comprised of polymeric materials. As a result, electrodeposition cannot be used on its own to form the inductor coil on the outer surface of the tubular frame, as the tubular frame is unable to form the cathode of an electrolytic cell onto which an electric circuit trace may be deposited.

[0020] However, the inventors realised that techniques for forming moulded interconnect devices (MIDs) may be adapted to form the inductor coil module. MIDs are typically injection-moulded polymeric components, often thermoplastic components, with electronic circuits directly integrated onto the polymeric component. In particular, the inventors realised that metallization of the tubular frame may be achievable via electroless plating methods.

[0021] Electroless plating comprises a controlled, autocatalytic deposition process in which metals and metal alloys may be deposited onto a catalytic surface by the reaction of a source of metal cation and a chemical reducing agent. Electroless plating methods may be used to deposit certain metals, such as copper, onto non-metallic materials such as polymeric materials.

[0022] A further challenge faced by the inventors was how to selectively metallize the tubular frame to produce electric circuit traces. Electroless plating methods are not, typically, selective. As such, a single layer, or body, of metal is deposited onto an outer surface of the substrate during the electroless plating process, coating the outer surface of the substrate. Depositing such a single metal layer onto the outer surface of the tubular frame, covering the outer surface, would not result in the outer surface of the tubular frame comprising a discrete electric trace in the form of a helical inductor coil, as required.

[0023] The inventors realised that it may be possible to achieve the required selective metallization of the tubular frame using selective irradiation of the outer surface of the tubular frame with a laser, either before or during the electroless plating process. The inventors have devised several methods of laser irradiation of the tubular frame which are suitable for producing the required selective metallization of the outer surface of the tubular frame to form electrical traces in the form of a helicoidal track, as described in more detail below.

[0024] Advantageously, selectively depositing the helical coil on the tubular frame, circumscribing the cavity of the tubular frame, reduces the amount of complex automation equipment required to form the inductor coil, compared to winding a wire coil around the tubular frame. For example, where the coil is deposited onto the tubular frame rather than wound around the tubular frame, there is no need to correctly tension a wire to be wound around the tubular frame, there is no need to glue or cure the coil to the tubular frame to secure the coil to the tubular frame, and there is no need to bend a wire in the formation of the coil module.

[0025] Advantageously, selectively depositing the helical coil on the tubular frame, circumscribing the cavity of the tubular frame, improves the accuracy of the coil placement around the tubular frame, and the accuracy of the arrangement of the windings of the coil on the tubular frame, reducing the inductance span of the coil module.

[0026] Advantageously, selectively depositing the helical coil on the tubular frame, circumscribing the cavity of the tubular frame, enables a greater flexibility in coil design to be achieved compared to winding a coil on the tubular frame. For example, selective deposition may enable the coil to have a pitch or shape that varies along the length of the tubular frame. Selective deposition may enable the coil to have non-uniform geometry along its length. This may enable the magnetic field intensity generated by the coil, both inside the cavity and outside the cavity, to be optimised.

[0027] The inductor coil module comprises a tubular frame.

[0028] The tubular frame may be formed from any suitable material. The tubular frame typically comprises a polymeric material. Preferably, the polymeric material comprises at least one of polyetheretherketone (PEEK), liquid crystal polymer (LCP), polysulfone (PSU), polyethersulfone (PES), polyetherimide (PEI) and polyphenylsulfone (PPS). Advantageously, these materials are able to withstand the high temperatures to which an aerosol-forming substrate received in the cavity is heated to generate an aerosol. The aerosol-forming substrate may be heated to temperatures of up to

[0029] 300 degrees Celsius, up to 270 degrees Celsius, up to 265 degrees Celsius, up to 260 degrees Celsius, up to 255 degrees Celsius, or up to 250 degrees Celsius.

[0030] In some embodiments, the polymeric material is a polar polymeric material. In some embodiments, the polymeric material is a non-polar polymeric material.

[0031] In some embodiments, the tubular frame is not formed from a material comprises a laser- activated filler. In some embodiments, the tubular frame does not comprise a material comprising a laser activated filler.

[0032] In some embodiments, the tubular frame is a moulded component. In some embodiments, the tubular frame is injection moulded. Where the tubular frame is moulded, particularly injection moulded, the tubular frame may be moulded with the helicoidal track on the outer surface of the tubular frame. The helicoidal track may be raised on the outer surface of the tubular frame. The helicoidal track may be recessed in the outer surface of the tubular frame. A border on opposite sides of the helicoidal track may be raised on the outer surface of the tubular frame.

[0033] The method may comprise moulding the tubular frame. In particular, the method may comprise injection moulding the tubular frame. The method may comprise moulding the tubular frame with the helicoidal track on the outer surface of the tubular frame. Advantageously, moulding the helicoidal track on the outer surface of the tubular frame may facilitate directing the laser beam at the helicoidal track on the outer surface of the tubular frame.

[0034] The tubular frame has an inner surface defining a cavity. The cavity may be for receiving an aerosol-forming substrate when the inductor coil module is in use in an aerosol-generating device. The cavity may be configured to receive an aerosol-forming substrate when the coil module is in use in an aerosol-generating device.

[0035] The cavity may have an open end. The open end may be for insertion of aerosol-forming substrate into the cavity. The open end may be for removal of aerosol-forming substrate from the cavity.

[0036] In some embodiments, the cavity may have two open ends. The cavity may have a first open end and a second open end, opposite the first open end.

[0037] The plating of the metal onto the portion of the outer surface of the tubular frame may form an inductor coil of the inductor coil module. The metal helical coil plated or deposited on the portion of the outer surface of the tubular frame forms an inductor coil of the inductor coil module.

[0038] The inductor coil module comprises an inductor coil. The inductor coil circumscribes the cavity of the tubular frame. The inductor coil is a helicoidal track circumscribing the cavity of the tubular frame. The inductor coil is formed from metal. The inductor coil comprises a metal helicoidal track circumscribing the cavity of the tubular frame. The inductor coil is a metallic helicoidal track plated or deposited on a portion of the outer surface of the tubular frame.

[0039] The metal track plated on the portion of the outer surface of the tubular frame may be formed from any suitable metal. The metal track may be formed from a metal that is able to be plated onto the portion of the outer surface of the tubular frame. For example, the metal may comprise at least one of copper, gold, nickel, platinum, palladium and silver. Preferably, the metal track is formed from nonmagnetic materials.

[0040] The inductor coil is formed from any suitable metal. The inductor coil may be formed from a metal that is able to be plated onto the portion of the outer surface of the tubular frame. The inductor coil may be formed from at least one of copper, gold, nickel, platinum, palladium, and silver. Preferably, the metal track is formed from non-magnetic materials.

[0041] The metal track may have any suitable thickness. The metal track may have a thickness of between 5 micrometres and 150 micrometres. The metal track may have a thickness of between 10 micrometres and 125 micrometres. The metal track may have a thickness of between 20 micrometres and 100 micrometres. The metal track may have a thickness of between 60 micrometres and 100 micrometres. The metal track may have a thickness of at least 60 micrometres, at least 70 micrometres or at least 80 micrometres. The metal track may have a thickness of up to 100 micrometres, up to 90 micrometres, or up to 80 micrometres.

[0042] The helicoidal track on the portion of the outer surface of the tubular frame may have any suitable form. In other words, the inductor coil of the inductor coil module may have any suitable form.

[0043] The inductor coil may have any suitable length. The inductor coil may have any suitable number of turns. The inductor coil may have any suitable pitch. The metal track forming the inductor coil may have any suitable width.

[0044] In some embodiments, the geometry of the inductor coil varies along the length of the tubular frame. The pitch of the inductor coil may vary along the length of the tubular frame. The pitch of the helicoidal track may vary along the length of the tubular frame.

[0045] The width of the helicoidal track may vary along the length of the tubular frame.

[0046] In some embodiments, the tubular frame has a longitudinal axis, and the helicoidal track has a geometry that varies along the longitudinal axis of the tubular frame. The pitch of the helicoidal track may vary along the longitudinal axis of the tubular frame. The width of the helicoidal track may vary along the longitudinal axis of the tubular frame.

[0047] Advantageously, selectively depositing the helicoidal track on the tubular frame, circumscribing the cavity of the tubular frame, enables a greater flexibility in coil design to be achieved compared to winding a coil on the tubular frame. For example, selective deposition may enable the inductor coil of the inductor coil module to have a pitch or shape that varies along the length of the tubular frame. Selective deposition may enable the coil to have non-uniform geometry along its length. This may enable the magnetic field intensity generated by the coil, both inside the cavity and outside the cavity, to be optimised.

[0048] In some embodiments, the inductor coil module comprises a single inductor coil.

[0049] In some embodiments, the inductor coil module comprises a plurality of inductor coils. Where the inductor coil module comprises a plurality of inductor coils, each inductor coil of the inductor coil module may be separate from the other inductor coils of the inductor coil module. In other words, the inductor coil module may comprise a plurality of discrete metal helicoidal tracks plated on the outer surface of the tubular frame.

[0050] The inductor coil module may comprise any suitable number of inductor coils. For example, the inductor coil module may comprise one, two, three, four, five or six inductor coils.

[0051] In some embodiments, the laser beam is directed onto a first portion of the outer surface of the tubular frame and a second portion of the outer surface of the tubular frame, the second portion being separate from the first portion. In these embodiments, the first portion of the outer surface of the tubular frame is a first helicoidal track circumscribing the cavity. In some of these embodiments, the second portion of the outer surface of the tubular frame is a second helicoidal track circumscribing the cavity.

[0052] Where the inductor coil module comprises a first inductor coil and a second inductor coil, the first inductor coil and the second inductor coil may have the same geometries. The number of turns of the first inductor coil may be the same as the number of turns of the second inductor coil.

[0053] Where the inductor coil module comprises a first inductor coil and a second inductor coil, the geometries of the inductor coils may be different to each other. For example, the pitch of the first inductor coil may be different to the pitch of the second inductor coil. In other words, the pitch of the first helicoidal track may be different to the pitch of the second helicoidal track. The width of the first helicoidal track may be different to the width of the second helicoidal track. The number of turns of the first inductor coil may be different to the number of turns of the second inductor coil.

[0054] The inductor coil of the inductor coil module is in the form of a three-dimensional coil on the outer surface of the tubular body, circumscribing the cavity of the tubular body. A further significant challenge faced by the inventors in providing an improved method of forming an inductor coil module having such an inductor coil was how to selectively metallize the tubular frame to produce electric circuit traces in the form of a three-dimensional helical coil on the outer surface of the tubular frame, circumscribing the cavity of the tubular body.

[0055] In some embodiments, the method comprises the step of moving the laser beam relative to the tubular frame while the laser beam is being directed onto the outer surface of the tubular frame. In some embodiments, the tubular frame has a longitudinal axis, and the method further comprises the step of rotating the laser beam about the longitudinal axis of the tubular frame while the laser beam is being directed onto the outer surface of the tubular frame. In some embodiments, the tubular frame has a longitudinal axis, and wherein the method further comprises the step of moving the laser beam along the longitudinal axis of the tubular frame while the laser beam is being directed onto the outer surface of the tubular frame.

[0056] In some embodiments, the tubular frame is held stationary while the laser is directed onto the outer surface of the tubular frame in the pattern of a helicoidal track circumscribing the cavity of the tubular body. In some of these embodiments, the laser is rotated about the tubular frame. The tubular frame may have a central longitudinal axis and the laser may be rotated about the longitudinal axis of the tubular frame. This may enable the laser to illuminate the outer surface of the tubular frame around its circumference. In some of these embodiments, the tubular frame has a central longitudinal axis and the laser is moved in the direction of the central longitudinal axis of the tubular frame. This may enable the laser to illuminate the outer surface of the tubular frame along its length. In some of these embodiments, the tubular frame has a central longitudinal axis, and the laser is both rotated about the tubular frame and moved in the direction of the central longitudinal axis of the tubular frame. This may enable the laser to illuminate the outer surface of the tubular frame around its circumference and along its length.

[0057] In some preferred embodiments, the method comprises the step of moving the tubular frame relative to the laser beam while the laser beam is being directed onto the outer surface of the tubular frame. In some of these preferred embodiments, the tubular frame has a longitudinal axis, and the method further comprises the step of rotating the tubular frame about its longitudinal axis while the laser beam is being directed onto the outer surface of the tubular frame. In some of these preferred embodiments, the tubular frame has a longitudinal axis, and the method further comprises the step of moving the tubular frame along its longitudinal axis while the laser beam is being directed onto the outer surface of the tubular frame.

[0058] In some preferred embodiments, the laser is held stationary while the laser is directed onto the outer surface of the tubular frame. In some of these preferred embodiments, the tubular frame is rotated. The tubular frame may have a central longitudinal axis, and the tubular frame may be rotated about its central longitudinal axis. This may enable the laser to illuminate the outer surface of the tubular frame around its circumference. Rotating the tubular frame, rather than rotating the laser, about the central longitudinal axis of the tubular frame, may be preferable, as rotating the tubular frame about its central longitudinal axis may require equipment that is more compact and more straightforward to operate. In some embodiments, the tubular frame has a central longitudinal axis and the tubular frame is moved along its central longitudinal axis. This may enable the laser to illuminate the outer surface of the tubular along its length. In some of these embodiments, the tubular frame has a central longitudinal axis, and the tubular frame is both rotated about its central longitudinal axis and moved along its central longitudinal axis. This may enable the laser to illuminate the outer surface of the tubular frame around its circumference and along its length.

[0059] In some embodiments, the tubular frame has a central longitudinal axis, the tubular frame is rotated about its central longitudinal axis and the laser is moved in the direction of the central longitudinal axis of the tubular frame. This may enable the laser to illuminate the outer surface of the frame around its circumference and along its length.

[0060] Where the laser beam is moved, the laser generating the laser beam may be moved by any suitable means. The laser may be moved by a galvanometric scanner. Where the laser is moved in the direction of the central longitudinal axis of the tubular frame, the laser may be moved by a galvanometric scanner. Moving the laser using a galvanometric scanner may enable precise movement of the laser, and particularly precise direction of the laser beam onto the outer surface of the tubular frame along the length of the tubular frame.

[0061] Any suitable laser may be used in the method to generate the laser beam. The laser may operate in any suitable region of the electromagnetic spectrum. The laser may generate radiation in the infrared region of the electromagnetic spectrum. The laser may generate radiation in the visible region of the electromagnetic spectrum. The laser may generate radiation in the ultraviolet regions of the electromagnetic spectrum. Any lasers, such as pulsed or continuous gas, solid-state, diode or excimer lasers may be used in the method, provided that the outer surface of the tubular frame sufficiently absorbs the laser radiation and the laser power is sufficient. For example, the laser may be a carbon dioxide laser (CO2 laser), a fibre laser, a diode laser, a neodymium-doped yttrium aluminium garnet laser (Nd:YAG laser), an ytterbium-doped yttrium aluminium garnet laser (Yb:YAG laser), or a neodymium-doped yttrium orthovanadate laser (Nd:YVO4).

[0062] A suitable laser generally has a power consumption of at least 5 Watts, at least 10 Watts, at least 15 Watts, at least 20 Watts, at least 25 Watts, at least 30 Watts, at least 35 Watts, at least 40 Watts, at least 45 Watts, at least 50 Watts, at least 55 Watts, or at least 60 Watts.

[0063] The laser beam generated by the laser may have any suitable properties.

[0064] The wavelength of the laser beam generated by the laser may be in the range of between 150 nanometres and 10600 nanometres, and may be in the range of between 600 nanometres and about 10600 nanometres.

[0065] The focal diameter of the laser beam generated by the laser may be between 1 micrometre and 100 micrometres, and may be between 5 micrometres and 50 micrometres.

[0066] The laser beam may have suitable properties to ablate or etch the portion of the outer surface of the tubular frame onto which the laser beam is directed. The properties of the laser beam required to ablate or etch the portion of the outer surface of the tubular frame may vary, depending on the material from which the tubular frame is formed. Preferably, the laser beam is directed onto a portion of the outer surface of the tubular frame to promote plating of the metal onto the outer surface of the tubular frame. Promotion of plating of the metal onto the outer surface of the tubular frame may be achieved in a plurality of ways.

[0067] In some embodiments, directing the laser beam onto the portion of the outer surface of the tubular frame activates a laser-activated filler within the material forming the tubular frame, at the portion of the outer surface of the tubular frame exposed to the laser beam. In these embodiments, activation of the laser-activated filler at the portion of the outer surface of the tubular frame promotes plating of the portion of the outer surface of the tubular frame.

[0068] In some embodiments, directing the laser beam onto the portion of the outer surface of the tubular frame etches the helicoidal track onto the outer surface of the tubular frame. In some of these embodiments, the etching of the helicoidal track onto the outer surface of the tubular frame promotes plating of the portion of the outer surface of the tubular frame. Without being bound by theory, it is believed that exposure to the laser beam introduces porous, rough structures on the surface of the tubular frame, which favour attachment of certain metal ions, such as palladium.

[0069] In some embodiments, directing the laser beam onto the portion of the outer surface of the tubular frame locally heats the portion of the outer surface of the tubular frame, which promotes plating of the portion of the outer surface of the tubular frame.

[0070] In some preferred embodiments, the tubular frame is formed from a material comprising a laser- activated filler. Typically, the tubular frame is formed from a polymeric material comprising a laser- activated filler. The laser-activated filler becomes catalytic to electroless metal deposition after exposure to the laser beam. Directing the laser beam onto the portion of the outer surface of the tubular frame may activate the laser-activated filler at the portion of the outer surface of the tubular frame. Activation of the laser-activated filler at the portion of the outer surface of the tubular frame may promote plating of the portion of the outer surface of the tubular frame with the metal.

[0071] The laser-activated filler may comprise at least one of an organometallic complex, a heavy metal complex comprising palladium, an inorganic spinel compound, titanium dioxide (TiO2), aluminium nitride (AIN) and zirconium dioxide (ZrO2). The laser-activated filler may comprise a metal salt. For example, the laser activated filler may comprise a copper salt, such as copper phosphate. The laser-activated filler may comprise a copper composite metal oxide, complexes of copper and its compounds, and tin compounds. Preferably, the laser- activated filler may comprise palladium.

[0072] In embodiments in which the tubular frame is formed from a material comprising a laser- activated filler, the laser beam may be directed onto the portion of the outer surface of the tubular frame before the outer surface of the tubular frame is contacted with the plating solution. In these embodiments, the tubular frame may be submerged in a liquid, such as water, while the laser beam is directed onto the portion of the outer surface of the tubular frame. In these embodiments, directing the laser beam onto the outer surface of the tubular frame may etch the outer surface of the tubular frame, exposing and activating the laser-activated filler and promoting plating of the metal at the portion of the outer surface of the tubular frame exposed to the laser beam. Exposure of the portion of the outer surface of the tubular frame to the laser beam may create porous, rough structures, such as pores and coral-like structures, at the portion of the outer surface exposed to the laser beam, which may further promote plating of the metal to the portion of the outer surface of the tubular frame.

[0073] In some preferred embodiments, particularly where the tubular frame is not formed from a material comprising a laser-activated filler, the portion of the outer surface of the tubular frame that is exposed to the laser beam requires activation by coating with a catalyst before the outer surface of the tubular frame is contacted with the plating solution. The catalyst may promote plating of the metal onto the outer surface of the tubular frame.

[0074] The method may further comprise the step of contacting the outer surface of the tubular frame with a catalyst solution. The method may comprise the step of contacting the outer surface of the tubular frame with a catalyst solution before contacting the outer surface of the tubular frame with the plating solution.

[0075] The catalyst solution comprises a catalyst that is catalytic to electroless metal deposition.

[0076] The catalyst may be any suitable catalyst that is catalytic to electroless deposition of the metal. Preferably, the catalyst solution comprises at least one of palladium, such as a palladium-tin colloidal suspension, and silver, such as silver nitrate.

[0077] The outer surface of the tubular frame may be contacted with the catalyst solution by any suitable means. Preferably, the tubular frame is submerged in the catalyst solution to contact the outer surface of the tubular frame with the catalyst solution. The method may comprise submerging the tubular frame in a catalyst solution to contact the outer surface of the tubular frame with the catalyst solution.

[0078] In some embodiments, the method may comprise the step of contacting the outer surface of the tubular frame with a catalyst solution after the laser beam is directed onto the portion of the outer surface of the tubular frame. The step of contacting the outer surface of the tubular frame with a catalyst solution may occur before the step of contacting the outer surface of the tubular frame with the plating solution and after the step of directing the laser beam onto the portion of the outer surface of the tubular frame.

[0079] In some embodiments where the outer surface of the tubular frame is contacted with the catalyst solution after the laser beam is directed onto the portion of the outer surface of the tubular frame, the tubular frame may be submerged in a liquid, such as water, while the laser beam is directed onto the portion of the outer surface of the tubular frame. Exposure of the portion of the outer surface of the tubular frame to the laser beam before contact with the catalyst solution may create porous, rough structures, such as pores and coral-like structures, at the portion of the outer surface exposed to the laser beam, which may promote attachment of the catalyst to the portion of the outer surface of the tubular frame exposed to the laser beam. As such, the catalyst may attach to the portion of the outer surface of the tubular frame exposed to the laser beam at a faster rate than to other portions of the outer surface of the tubular frame. This may result in selective coating of the portion of the outer surface of the tubular frame exposed to the laser beam with the catalyst. The other portions of the outer surface of the tubular frame may not be coated with the catalyst, or may be coated with much less of the catalyst than the portion of the outer surface exposed to the laser beam.

[0080] In some embodiments, the method may comprise the step of contacting the outer surface of the tubular frame with a catalyst solution before the laser beam is directed onto the portion of the outer surface of the tubular frame. In some embodiments where the step of contacting the outer surface of the tubular frame with a catalyst solution occurs before the step of contacting the outer surface of the tubular frame with the plating solution, the laser beam is directed onto the portion of the outer surface of the tubular frame while the outer surface of the tubular frame is in contact with the plating solution. In these embodiments, the laser beam directed onto the portion of the outer surface of the tubular frame may locally heat the portion of the outer surface of the tubular frame to promote plating of the metal onto the portion of the outer surface exposed to the laser beam. The heating of the portion of the outer surface of the tubular frame by the laser beam may increase the rate of plating of the metal onto the heated portion of the tubular frame compared to the other, non-heated, portions of the outer surface of the tubular frame. This may result in selective plating of the portion of the outer surface of the tubular frame exposed to the laser beam with the metal. The other portions of the outer surface of the tubular frame may not be plated with the metal, or may be plated with much less of the metal than the portion of the outer surface exposed to the laser beam.

[0081] The method comprises contacting the outer surface of the tubular frame with a plating solution.

[0082] The plating solution may be any suitable plating solution for plating the metal onto the portion of the outer surface of the tubular frame. The plating solution may be any suitable plating solution for plating the metal onto the portion of the outer surface of the tubular frame without application of an electric potential. The plating solution may be any suitable plating solution for electroless plating of the metal onto the portion of the outer surface of the tubular frame.

[0083] In some preferred embodiments, the plating solution comprises a source of metal ions. The metal of the metal ions is the metal to be plated onto the outer surface of the tubular frame. Preferably, the metal comprises at least one of copper, nickel, palladium, gold, and silver. Particularly preferably, the source of metal ions comprises a metal salt. The plating solution may comprise copper sulphate, such as copper (II) sulphate pentahydrate.

[0084] In some preferred embodiments, the plating solution comprises a reducing agent. The reducing agent may comprise at least one of sodium hypophosphite, amino boranes, sodium borohydride, and hydrazine or hydrazine hydrate.

[0085] The plating solution may contain a source of metal ions, a reducing agent, and one or more other components, such as a complexing agent, a stabilizer, a buffering agent, and a wetting agent.

[0086] The outer surface of the tubular frame may be contacted with the plating solution by any suitable means. Preferably, the tubular frame is submerged in the plating solution to contact the outer surface of the tubular frame with the plating solution. The method may comprise submerging the tubular frame in a plating solution to contact the outer surface of the tubular frame with the plating solution.

[0087] Where the tubular frame is submerged in the plating solution, the temperature of the plating solution may be controlled while the tubular frame is submerged in the plating solution. The temperature of the plating solution may be any suitable temperature to promote plating of the metal onto the portion of the outer surface of the tubular frame. For example, the temperature of the plating solution may be maintained at between 20 degrees Celsius and 70 degrees Celsius, or between 30 degrees and 60 degrees, while the tubular frame is submerged in the plating solution.

[0088] Where the tubular frame is submerged in the plating solution, the pH of the plating solution may be controlled while the tubular frame is submerged in the plating solution. The pH of the plating solution may be any suitable pH to promote plating of the metal onto the portion of the outer surface of the tubular frame.

[0089] Where the tubular frame is submerged in the plating solution, the submersion time of the tubular frame in the plating solution may be controlled. The tubular frame may be submerged in the plating solution for any suitable time to promote plating of the desired thickness of the metal onto the portion of the outer surface of the tubular frame. For example, the tubular frame may be submerged in the plating solution for between 20 minutes and 60 minutes.

[0090] In some embodiments, the method further comprises a step of contacting the outer surface of the tubular frame with an etching solution before contacting the outer surface of the tubular frame with the plating solution. Contacting the outer surface of the tubular frame with an etching solution may further promote plating of the portion of the outer surface of the tubular frame with the metal when the outer surface of the tubular frame contacts the plating solution.

[0091] The etching solution may be any suitable etching solution. Preferably, the etching solution comprises an acid. Particularly preferably, the acid comprises at least one of sulfuric acid, chromic acid, and hydrofluoric acid. Without being bound by theory, it is believed that exposure to the acidic etching solution introduces porous, rough structures on the surface of the tubular frame, which favour attachment of certain metal ions, such as palladium.

[0092] The outer surface of the tubular frame may be contacted with the etching solution by any suitable means. Preferably, the tubular frame is submerged in the etching solution to contact the outer surface of the tubular frame with the plating solution. The method may comprise submerging the tubular frame in an etching solution to contact the outer surface of the tubular frame with the etching solution.

[0093] In some embodiments, the method comprises one or more steps of cleaning the outer surface of the tubular frame. The cleaning steps may involve contacting the outer surface of the tubular frame with a cleaning solution. The outer surface of the tubular frame may be contacted with the cleaning solution by any suitable means. For example, the outer surface of the tubular frame may be contacted with the cleaning solution by spraying the outer surface of the tubular frame with the cleaning solution or by submerging the outer surface of the tubular frame in the cleaning solution.

[0094] The cleaning solution may comprise any suitable solution capable of cleaning the outer surface of the tubular frame. For example, the cleaning solution may comprise at least one of water and ethanol.

[0095] In some embodiments, the cleaning solution may comprise a reducing agent to remove excessive oxidants from the outer surface of the tubular frame.

[0096] The method may further comprise a step of contacting the outer surface of the tubular frame with a cleaning solution before contacting the outer surface of the tubular frame with the plating solution.

[0097] The method may further comprise a step of contacting the outer surface of the tubular frame with a cleaning solution after contacting the outer surface of the tubular frame with the plating solution.

[0098] The method may further comprise a step of contacting the outer surface of the tubular frame with a cleaning solution before contacting the outer surface of the tubular frame with the catalyst solution.

[0099] The method may further comprise a step of contacting the outer surface of the tubular frame with a cleaning solution after contacting the outer surface of the tubular frame with the catalyst solution.

[0100] The method may further comprise a step of contacting the outer surface of the tubular frame with a cleaning solution before contacting the outer surface of the tubular frame with the etching solution.

[0101] The method may further comprise a step of contacting the outer surface of the tubular frame with a cleaning solution after contacting the outer surface of the tubular frame with the etching solution.

[0102] In some embodiments, the tubular frame comprises an open end. The open end of the tubular frame has an opening. The open end of the tubular frame may comprise an opening of the cavity. The opening may be for inserting aerosol-forming substrate into the cavity. The opening may be for removing aerosol-forming substrate from the cavity. Where the tubular frame comprises an open end, the open end may be temporarily covered during the method of forming the inductor coil module, so that the inner surface of the tubular frame is not exposed to any of the solutions with which the outer surface of the tubular frame is contacted.

[0103] In some embodiments, the method comprises the step of closing the opening of the open end of the tubular frame with a cap. The method may comprise the step of closing the opening of the open end of the tubular frame with a cap before contacting the outer surface of the tubular frame with the plating solution. The method may comprise the step of closing the opening of the open end of the tubular frame with a cap before contacting the outer surface of the tubular frame with the catalyst solution. The method may comprise the step of closing the opening of the open end of the tubular frame with a cap before contacting the outer surface of the tubular frame with the etching solution.

[0104] The cap may take any suitable form and be formed from any suitable material that is impermeable to the catalyst solution and / or the plating solution. The cap may take any suitable form and be formed from any suitable material that is not reactive with the catalyst solution and / or the plating solution, and / or is not degraded by the catalyst solution and / or the plating solution.

[0105] In some embodiments, the tubular frame comprises two open ends. Each open end may have an opening. In these embodiments, the method may further comprise the step of closing each opening with a cap. The method may further comprise the step of closing each opening with a cap before contacting the outer surface of the tubular frame with the plating solution. The method may further comprise the step of closing each opening with a cap before contacting the outer surface of the tubular frame with the catalyst solution. The method may further comprise the step of closing each opening with a cap before contacting the outer surface of the tubular frame with the etching solution.

[0106] In some cases, electroless plating of the helicoidal track on the portion of the outer surface of the tubular frame may not be sufficient on its own produce an electrically conductive track with the desired electrical conductivity for the electrically conductive track to form an inductor coil of the inductor coil module. In these cases, after a layer of the metal is plated on the portion of the outer surface of the tubular frame, electroplating may be used to further deposit metal onto the helicoidal track to produce an electrically conductive track with the desired electrical conductivity.

[0107] Electroless plating followed by subsequent electroplating, may be advantageous for several reasons.

[0108] Advantageously, electroplating typically has a faster deposition rate than electroless plating, and so the combination of electroless plating and subsequent electroplating may achieve a plated metal track with the desired thickness faster than electroless plating on its own.

[0109] In some cases, electroless plating of the desired metal onto the portion of the outer surface of the tubular frame may not be possible, and so it may be necessary to plate the portion of the outer surface of the tubular frame with a less desirable metal using electroless plating. In these cases, a layer of the less desirable metal may be initially plated onto the portion of the outer surface of the tubular frame using electroless plating, and subsequently the desired metal may be plated over the layer of the less desirable metal using electroplating.

[0110] For example, for some tubular frames formed from particular polymers, it may not be possible, or practical, to directly plate the portion of the outer surface of a tubular frame with copper using electroless plating. In these cases, it may be possible to plate the portion of the outer surface of a tubular frame with nickel or silver using electroless plating. However, the nickel or the silver may not have the desired electrical properties to form a suitable inductor coil of the inductor module. In these cases, it may be advantageous to plate the portion of the outer surface of the tubular frame with an initial layer of nickel using electroless plating, and to subsequently plate over the layer of nickel with a layer of copper using electroplating to achieve an electrical track with the desired electrical properties to form an inductor coil of the inductor module.

[0111] In some embodiments, the method may further comprise contacting the outer surface of the tubular frame with an electroplating solution in the presence of an applied electric potential, to plate a portion of the outer surface of the tubular frame with a metal. The outer surface of the tubular frame is contacted with an electroplating solution in the presence of an applied electric potential after the outer surface of the tubular frame is contacted with the plating solution.

[0112] In some embodiments, the metal plated onto the portion of the outer surface of the tubular frame from the electroplating solution is same metal plated onto the portion of the outer surface of the tubular frame from the plating solution. In some embodiments, the metal plated onto the portion of the outer surface of the tubular frame from the electroplating solution is a different metal to the metal plated onto the portion of the outer surface of the tubular frame from the plating solution.

[0113] The electroplating solution may be an electrolyte. The electroplating solution may comprise a metal salt. The metal of the metal salt may be the metal to be plated onto the portion of the outer surface of the tubular frame. The metal may be any suitable metal. Preferably, the metal is copper.

[0114] In some embodiments, a protective layer may be provided over the metal track deposited on the tubular frame. The protective layer may be formed from any suitable material for protecting the metal track. In some preferred embodiments, the protective layer may be formed from a metal, such as silver. The protective layer may be deposited onto the metal track on the tubular frame. The protective layer may be deposited onto the metal track by electrodeposition.

[0115] The method may further comprise electrically connecting a flexible printed circuit to the plated helicoidal track circumscribing the cavity of the tubular frame. The flexible printed circuit may be electrically connected to the plated helicoidal track by any suitable method. Preferably, the flexible printed circuit is soldered to one or more ends of the plated helicoidal track. The flexible printed circuit may comprise one or more electrical tracks on an electrically insulating substrate. Preferably, the flexible printed circuit comprises two electrical tracks, one track for electrical connection to each end of the inductor coil of the inductor coil module. The electrically insulating substrate may be formed from any suitable material. For example, the electrically insulating substrate may be formed from polyimide.

[0116] In some preferred embodiments, as described above, the method of forming the inductor coil module for an aerosol-generating device comprises the steps of:

[0117] • providing a tubular frame comprising a polymeric material, the tubular frame having an outer surface and an inner surface, the inner surface defining a cavity for receiving an aerosol-forming substrate when the inductor coil module is in use in an aerosolgenerating device;

[0118] • directing a laser beam onto a portion of the outer surface of the tubular frame, the portion of the outer surface of the tubular frame being a helicoidal track circumscribing the cavity; and

[0119] • submerging the outer surface of the tubular frame in a plating solution to plate the portion of the outer surface with a metal to form an inductor coil circumscribing the cavity.

[0120] In some of these preferred embodiments, the tubular frame is formed from a polymeric material comprising a laser-activated filler. In these embodiments, the laser beam is directed onto the portion of the outer surface of the tubular frame before submerging the outer surface of the tubular frame in the plating solution.

[0121] In these preferred embodiments, the tubular frame is submerged in the plating solution in the absence of an applied electric potential, such that the plating is achieved by electroless deposition.

[0122] In some preferred embodiments, as described above, the method of forming the inductor coil module for an aerosol-generating device comprises the steps of:

[0123] • providing a tubular frame comprising a polymeric material, the tubular frame having an outer surface and an inner surface, the inner surface defining a cavity for receiving an aerosol-forming substrate when the inductor coil module is in use in an aerosolgenerating device;

[0124] • directing a laser beam onto a portion of the outer surface of the tubular frame, the portion of the outer surface of the tubular frame being a helicoidal track circumscribing the cavity;

[0125] • submerging the outer surface of the tubular frame in a catalyst solution; and • submerging the outer surface of the tubular frame in a plating solution to plate the portion of the outer surface with a metal to form an inductor coil circumscribing the cavity.

[0126] In these preferred embodiments, the outer surface of the tubular frame is submerged in the catalyst solution before the outer surface of the tubular frame is submerged in the plating solution.

[0127] In some of these preferred embodiments, the laser beam is directed onto the portion of the outer surface of the tubular frame before submersion of the outer surface of the tubular frame in the catalyst solution.

[0128] In some of these preferred embodiments, the laser beam is directed onto the portion of the outer surface of the tubular frame while the outer surface of the tubular frame is submerged in the plating solution.

[0129] In these preferred embodiments, the tubular frame is submerged in the plating solution in the absence of an applied electric potential, such that the plating is achieved by electroless deposition.

[0130] The invention is defined in the claims. However, below there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

[0131] 1 . A method of forming an inductor coil module for an aerosol-generating device, the method comprising: providing a tubular frame having an outer surface and an inner surface, the inner surface defining a cavity for receiving an aerosol-forming substrate when the inductor coil module is in use in an aerosol-generating device; and contacting the outer surface of the tubular frame with a plating solution to plate a portion of the outer surface with a metal, wherein a laser beam is directed onto the portion of the outer surface of the tubular frame, the portion of the outer surface of the tubular frame being a helicoidal track circumscribing the cavity.

[0132] 2. A method according to example 1 , wherein the laser beam is directed onto a portion of the outer surface of the tubular frame to promote plating of the metal onto the outer surface of the tubular frame.

[0133] 3. A method according to any one of examples 1 or 2, wherein the tubular frame is formed from a polymeric material, and preferably wherein the polymeric material comprises at least one of polyetheretherketone (PEEK), liquid crystal polymer (LCP), polysulfone (PSU), polyethersulfone (PES), polyetherimide (PEI) and polyphenylsulfone (PPS).

[0134] 4. A method according to example 3, wherein the laser beam etches the helicoidal track onto the outer surface of the tubular frame when the laser beam is directed onto the portion of the outer surface of the tubular frame, and preferably wherein the etching of the helicoidal track onto the outer surface of the tubular frame promotes plating of the portion of the outer surface of the tubular frame.

[0135] 5. A method according to any one of examples 3 or 4, wherein the polymeric material comprises a laser-activated filler that becomes catalytic to electroless metal deposition after exposure to the laser beam, and preferably wherein the laser-activated filler comprises at least one of an organometallic complex, an inorganic spinel compound, titanium dioxide (TiO2), aluminium nitride (AIN) and zirconium dioxide (ZrO2).

[0136] 6. A method according to example 5, wherein directing the laser beam onto the portion of the outer surface of the tubular frame activates the laser-activated filler at the portion of the outer surface of the tubular frame, and preferably wherein activation of the laser-activated filler at the portion of the outer surface of the tubular frame promotes plating of the portion of the outer surface of the tubular frame.

[0137] 7. A method according to any one of examples 1 to 6, wherein the laser beam is directed onto the portion of the outer surface of the tubular frame before the outer surface of the tubular frame is contacted with the plating solution.

[0138] 8. A method according to example 7, wherein the tubular frame is submerged in a liquid while the laser beam is directed onto the portion of the outer surface of the tubular frame, and preferably wherein the liquid is water.

[0139] 9. A method according to any one of examples 1 to 8, wherein the method further comprises the step of contacting the outer surface of the tubular frame with a catalyst solution before contacting the outer surface of the tubular frame with the plating solution, and preferably wherein the catalyst solution comprises at least one of palladium, such as a palladium-tin colloidal suspension, and silver, such as silver nitrate.

[0140] 10. A method according to example 9, wherein the step of contacting the outer surface of the tubular frame with a catalyst solution occurs before contacting the outer surface of the tubular frame with the plating solution and after the laser beam is directed onto a portion of the outer surface of the tubular frame.

[0141] 11. A method according to any one of examples 1 to 6, wherein the laser beam is directed onto the portion of the outer surface of the tubular frame while the outer surface of the tubular frame is in contact with the plating solution.

[0142] 12. A method according to example 11 , wherein the laser beam directed onto the portion of the outer surface of the tubular frame locally heats the portion of the outer surface of the tubular frame to promote plating.

[0143] 13. A method according to any one of examples 11 or 12, wherein the method further comprises the step of contacting the outer surface of the tubular frame with a catalyst solution before contacting the outer surface of the tubular frame with the plating solution, and preferably wherein the catalyst solution comprises at least one of palladium, such as a palladium-tin colloidal suspension, and silver, such as silver nitrate.

[0144] 14. A method according to any one of examples 1 to 13, wherein the plating solution comprises a source of metal ions, the metal being the metal to be plated onto the outer surface of the tubular frame, preferably wherein the metal comprises at least one of copper, nickel, palladium and gold, and preferably wherein the source of metal ions comprises a metal salt.

[0145] 15. A method according to any one of examples 1 to 14, wherein the plating solution comprises a reducing agent, and preferably wherein the reducing agent comprises at least one of sodium hypophosphite, amino boranes, sodium borohydride, and hydrazine or hydrazine hydrate.

[0146] 16. A method according to any one of examples 1 to 15, wherein the method comprises the step of moving the tubular frame relative to the laser beam while the laser beam is being directed onto the outer surface of the tubular frame.

[0147] 17. A method according to any one of examples 1 to 16, wherein the tubular frame has a longitudinal axis, and wherein the method further comprises the step of rotating the tubular frame about its longitudinal axis while the laser beam is being directed onto the outer surface of the tubular frame.

[0148] 18. A method according to any one of examples 1 to 17, wherein the tubular frame has a longitudinal axis, and wherein the method further comprises the step of moving the tubular frame along its longitudinal axis while the laser beam is being directed onto the outer surface of the tubular frame.

[0149] 19. A method according to any one of examples 1 to 18, wherein the method comprises the step of moving the laser beam relative to the tubular frame while the laser beam is being directed onto the outer surface of the tubular frame.

[0150] 20. A method according to any one of examples 1 to 19, wherein the tubular frame has a longitudinal axis, and wherein the method further comprises the step of rotating the laser beam about the longitudinal axis of the tubular frame while the laser beam is being directed onto the outer surface of the tubular frame.

[0151] 21 . A method according to any one of examples 1 to 20, wherein the tubular frame has a longitudinal axis, and wherein the method further comprises the step of moving the laser beam along the longitudinal axis of the tubular frame while the laser beam is being directed onto the outer surface of the tubular frame.

[0152] 22. A method according to any one of examples 1 to 21 , wherein the tubular frame comprises an open end having an opening for inserting aerosol-forming substrate into the cavity, and wherein the method comprises the step of closing the opening with a cap before contacting the outer surface of the tubular frame with the plating solution. 23. A method according to any one of examples 1 to 22, wherein the tubular frame comprises two open ends, wherein each open end has an opening, and wherein the method comprises the step of closing each opening with a cap before contacting the outer surface of the tubular frame with the plating solution.

[0153] 24. A method according to any one of examples 1 to 23, Wherein the step of contacting the outer surface of the tubular frame with the plating solution comprises submerging the tubular frame in the plating solution.

[0154] 25. A method according to example 24, wherein the temperature of the plating solution is maintained at between 20 degrees Celsius and 70 degrees Celsius while the tubular frame is submerged in the plating solution.

[0155] 26. A method according to any one of examples 24 or 25, wherein the tubular frame is submerged in the plating solution for between 20 minutes and 60 minutes.

[0156] 27. A method according to any one of examples 1 to 26, wherein the method further comprises a step of contacting the outer surface of the tubular frame with an etching solution before contacting the outer surface of the tubular frame with the plating solution, preferably wherein the etching solution comprises an acid, and preferably wherein the acid comprises at least one of sulfuric acid, chromic acid, and hydrofluoric acid.

[0157] 28. A method according to example 27, wherein the step of contacting the outer surface of the tubular frame with the etching solution comprises submerging the tubular frame in the etching solution

[0158] 29. A method according to any one of examples 1 to 28, wherein the method further comprises a step of contacting the outer surface of the tubular frame with a cleaning solution before contacting the outer surface of the tubular frame with the plating solution, optionally wherein the cleaning solution is one of water and ethanol.

[0159] 30. A method according to any one of examples 1 to 29, wherein the tubular frame has a longitudinal axis, and wherein the helicoidal track as a pitch that varies along the longitudinal axis of the tubular frame.

[0160] 31 . A method according to any one of examples 1 to 30, wherein the method further comprises electrically connecting a flexible printed circuit to the plated helicoidal track circumscribing the cavity of the tubular frame.

[0161] 32. A method according to any one of examples 1 to 31 , wherein a laser beam is directed onto a first portion of the outer surface of the tubular frame and a second portion of the outer surface of the tubular frame, the second portion being separate from the first portion, and wherein the first portion of the outer surface of the tubular frame is a first helicoidal track circumscribing the cavity, and optionally wherein the second portion of the outer surface of the tubular frame is a second helicoidal track circumscribing the cavity.

[0162] 33. A method according to example 32, wherein the pitch of the first helicoidal track is different to the pitch of the second helicoidal track

[0163] 34. An inductor coil module for an aerosol-generating device, the inductor coil module being formed by the method of any one of examples 31 -33.

[0164] 35. An inductor coil module for an aerosol-generating device, the inductor coil module comprising: a tubular frame formed from a polymeric material, the tubular frame having an outer surface and an inner surface, the inner surface defining a cavity for receiving an aerosol-forming substrate when the inductor coil module is in use in an aerosol-generating device; and an inductor coil circumscribing the cavity, the inductor coil being formed from a metallic helicoidal track deposited on a portion of the outer surface of the tubular frame.

[0165] Examples will now be further described with reference to the figures in which:

[0166] Figure 1 a shows a schematic representation of a tubular frame of an embodiment of an inductor coil module of the disclosure;

[0167] Figure 1 b shows a schematic representation of the tubular frame of Figure 1 a after a laser beam has been directed at a portion of the outer surface of the tubular frame.

[0168] Figure 1c shows a schematic representation of the tubular frame of Figure 1 b with a metal track plated on the portion of the outer surface of the tubular frame, after the tubular frame has been submerged in a plating solution, and a flexible printed circuit;

[0169] Figure 1d shows a schematic representation of the tubular frame of Figure 1 b and the flexible printed circuit of Figure 1 b electrically connected to form an inductor coil module;

[0170] Figure 2 shows a laser beam being directed at a portion of the outer surface of the tubular frame of Figure 1 a;

[0171] Figure 3 shows the tubular frame of Figure 1b submerged in a plating solution;

[0172] Figure 4a shows the inductor coil module of Figure 1d in use in an aerosol-generating system comprising an aerosol-generating device and an aerosol-generating article;

[0173] Figure 4b shows the aerosol-generating system of Figure 4a with the aerosol-generating article received in the aerosol-generating device;

[0174] Figure 5 shows a flow diagram of the method of forming the coil module of Figure 1d; and

[0175] Figure 6 shows a flow diagram of an alternative method of forming the coil module of Figure 1d.

[0176] Figures 1a-d show different stages in a method of forming an inductor coil module 1 for an aerosol-generating device, in accordance with an embodiment of the disclosure. Figure 1 a shows a tubular frame 2 for the inductor coil module 1 . The tubular frame comprises a polymeric material, which in this embodiment is polyetheretherketone (PEEK), which has been injection moulded into a tubular form. The tubular frame comprises an outer surface 3 and an inner surface 4. The inner surface 4 defines a cavity 5 for receiving an aerosol-forming substrate when the inductor coil module 1 is in use in an aerosol-generating device. In this embodiment, the outer surface 3 of the tubular frame 2 comprises a helicoidal track 6 moulded around the outer surface 3, as a helicoidal track circumscribing the cavity 5. The helicoidal track 6 is sunken into the outer surface 3 of the tubular frame 2, such that the helicoidal track 6 forms a channel on the outer surface 3 of the tubular frame 2. It will be appreciated that the tubular frame 2 does not require a helicoidal track 6 to be moulded around the outer surface 3, and other embodiments may not comprise the helicoidal track moulded around the outer surface. However, providing the helicoidal track 6 moulded around the outer surface of the tubular frame 2 may advantageously allow the inductor coil, when plated on the outer surface of the tubular frame, to lie flush with the outer surface of the tubular frame. This may help to protect the outer edges of the plated inductor coil.

[0177] Figure 1 b shows the tubular frame 2 after a laser beam has been directed at a portion of the outer surface 3 of the tubular frame 2. In this embodiment, the laser beam is directed at the helicoidal track 6, which is moulded around the outer surface of the tubular frame 2.

[0178] Figure 2 shows a schematic representation of the laser beam being directed at the outer surface 3 of the tubular frame 2. A laser source 8, is provided in the form of a Nd:YAG laser. The laser beam 9 is emitted from the laser source 8 and is modulated by a modulator 10, arranged between the laser source 8 and the tubular frame 2. In this embodiment, the modulator 10 comprises a mechanical light chopper, but may alternatively comprise an optical modulator. A lens system 11 is also arranged between the modulator 10 and the tubular frame 2 to concentrate the laser beam 9 further. It will be appreciated that one or both the modulator 10 and the lens system 11 may not be required in all embodiments.

[0179] Although not shown in Figure 2, the tubular frame 2 may be submerged in water while the laser beam is directed onto the outer surface.

[0180] In this embodiments, the laser source 8 is held stationary, and the tubular frame 2 so that the entire helicoidal track 6 on the outer surface 3 of the tubular frame 2 is exposed to the laser beam 9. The tubular frame 2 is rotated about its longitudinal axis and translated along its longitudinal axis, such that the laser beam is directed in a helicoidal pattern around the outer surface 3 of the tubular frame 2.

[0181] Exposure of the helicoidal track 6 on the outer surface 3 of the tubular frame 2 to the laser beam 9 creates porous, rough structures on the helicoidal track 6.

[0182] After the helicoidal track 6 on the outer surface 3 of the tubular frame 2 has been exposed to the laser beam 9, a cap (not shown) is positioned on an open end of the tubular frame 2 to close the cavity 5, protecting the inner surface 4 of the cavity 5. The tubular frame 2 is then submerged in a catalyst solution. In this embodiment, the catalyst solution comprises a palladium-tin colloidal suspension. The porous, rough structures on the helicoidal track 6, resulting from exposure to the laser beam 9, promote attachment of the palladium in the catalyst solution to the helicoidal track 6. As other portions of the outer surface 3 of the tubular frame 2 outside of the helicoidal track 6 do not comprise the porous, rough structures, the palladium does not readily attach to the other portions of the outer surface 3 of the tubular frame 2.

[0183] After removal of the tubular frame 2 from the catalyst solution, the tubular frame is cleaned with water, and subsequently submerged in a plating solution. Submersion of the tubular frame 2 in the plating solution 12 is shown in Figure 3.

[0184] The plating solution 12 comprises a source of metal ions. In this embodiment, the metal is copper, and the plating solution comprises copper (II) sulphate pentahydrate. The plating solution 12 further comprises a reducing agent, in the form of hydrazine hydrate. The copper ions in the plating solution deposit over the palladium attached to the porous, rough structures on the helicoidal track 6 on the outer surface 3 of the tubular frame 2. Since only the helicoidal track 6 on the outer surface 3 of the tubular frame 2 comprises the palladium catalyst, the helicoidal track 6 is the only portion of the outer surface 3 of the tubular frame 2 onto which the copper is plated.

[0185] The tubular frame 2 is submerged in the plating solution 12 in the absence of an applied electric potential, such that the plating is achieved by electroless deposition.

[0186] The duration of the contact between the plating solution and the outer surface 3 of the tubular frame 2 is determined based on the desired electrical conductivity of the plated helicoidal track, such that the plated helicoidal track forms an inductor coil 14 of the inductor coil module 1 , which circumscribes the cavity 5. When the tubular frame 2 is removed from the plating solution it is cleaned by submerging the tubular frame 2 in water, and when the tubular frame 2 is removed from the water, the cap is removed from the open end.

[0187] Figure 1c shows the tubular frame 2 after submersion in a catalyst solution and subsequent submersion in a plating solution to plate the helicoidal track 6 on the outer surface 3 of the tubular frame 2 with a metal. In this embodiment, the helicoidal track 6 is plated with copper.

[0188] Figure 1c also shows a flexible printed circuit 15, comprising two separate electrical tracks 16, 17 on an electrically insulating substrate, which in this embodiment is formed from polyimide.

[0189] Figure 1 d shows the completed inductor coil module 1 , comprising the tubular frame 2 plated with the helicoidal electrical track of Figure 1c electrically connected to the flexible printed circuit 15 of Figure 1c.

[0190] A first one of the electrical tracks 16 of the flexible printed circuit 15 is electrically connected to one end of the inductor coil 14 (i.e. the helicoidal electrical track plated on the outer surface 3 of the tubular frame 2), and a second one of the electrical tracks 17 of the flexible printed circuit 15 is electrically connected to the other end of the inductor coil 14 (i.e. the helicoidal electrical track plated on the outer surface 3 of the tubular frame 2). In this embodiment, the electrical tracks 16, 17 of the flexible printed circuit 15 are soldered to the ends of the inductor coil 14.

[0191] The flexible printed circuit 15 enables the inductor coil module 1 to be electrically connected to a power supply and control electronics of an aerosol-generating device, such that power may be supplied to the inductor coil 14.

[0192] In some embodiments, the tubular frame is formed from a polymeric material comprising a laser- activated filler. In these embodiments, the tubular frame does not require submersion in the catalyst solution before being submerged in the outer surface of the tubular frame in the plating solution. Exposure of the helicoidal track 6 to the laser beam 9 exposes and activates the laser-activated filler at the helicoidal track 6, and the activated laser-activated filler acts as a catalyst for plating the copper on the helicoidal track 6 when the tubular frame 2 is submerged in the plating solution 12.

[0193] In some embodiments, a further step of electroplating the plated helicoidal track 6 is performed to increase the thickness and / or improve the electrical properties of the plated helicoidal track, such that the inductor coil formed by the plated helicoidal track has the desired electrical properties.

[0194] Figures 4a and 4b show an aerosol-generating system 20 comprising an aerosol-generating device 21 and an aerosol-generating article 22.

[0195] The aerosol-generating device 21 comprises the inductor coil module 1 of Figure 1d. The aerosol-generating device further comprises a power supply 23, in the form of a rechargeable battery, and control electronics 24, which are both electrically connected to the inductor coil module 1 . The control electronics 24 are configured to control the supply of power from the power supply 23 to the inductor coil 14 of the inductor coil module 1 . The control electronics 24 are configured to provide an alternating electric current from the power supply 23 to the inductor coil 14 to generate an alternating magnetic field in the cavity 5 of the tubular frame 2.

[0196] The aerosol-generating article 22 comprises an aerosol-forming substrate 25 in the form of a gathered and crimped sheet of homogenised tobacco material, a first hollow acetate tube 26, a second hollow acetate tube 27, a mouthpiece 28, and an outer wrapper (not shown). The aerosol-generating article 22 also comprises a susceptor element 30 arranged within the aerosol-forming substrate 25.

[0197] During use, a portion of the aerosol-generating article 22 is inserted into the cavity 5 of the tubular frame 2, such that the inductor coil 14 of the inductor coil module 1 circumscribes the aerosolforming substrate 25 and the susceptor element 30 of the aerosol-generating article 22.

[0198] The control electronics 24 provides an alternating electric current from the power supply 23 to the inductor coil 14 to generate an alternating magnetic field in the cavity 5, which inductively heats the susceptor element 30, which heats the aerosol-forming substrate 25 to generate an aerosol. Figure 5 shows a flow diagram of a method 100 of forming the inductor coil module of Figure 1d.

[0199] The method 100 comprises a first step 101 of providing the tubular frame 2, which in this embodiment involves injection moulding the tubular frame 2 into a tubular form from PEEK.

[0200] The method 100 further comprises a second step 102 of directing the laser beam 9 onto a portion of the outer surface 3 of the tubular frame 2, the portion of the outer surface 3 of the tubular frame 2 being the helicoidal track 6 circumscribing the cavity 5.

[0201] The method 100 further comprises an optional third step 103 of covering an open end of the tubular frame 2 with the cap, to prevent liquid from entering the cavity 5 of the tubular frame 2.

[0202] In this embodiment, the method 100 further comprises a fourth step of submerging the outer surface 3 of the tubular frame 2 in the catalyst solution, removing the tubular frame 2 from the catalyst solution, and cleaning the tubular frame 2 with water.

[0203] In some embodiments, where the tubular frame is formed from a material comprising a laser- activated filler, the fourth step 104 may be omitted, as the laser-activated filler acts as a catalyst once activated by the laser.

[0204] The method 100 further comprises a fifth step 105 of submerging the outer surface 3 of the tubular frame 2 in the plating solution, to plate the portion 6 of the outer surface 3 with a metal to form an inductor coil circumscribing the cavity 5. In the fifth step 105, the tubular frame 2 is submerged in the plating solution in the absence of an applied electric potential, such that the plating is achieved by electroless deposition.

[0205] In a further optional step, not shown in Figure 5, the method 100 may further comprise electroplating the plated helicoidal track 6 to increase the thickness and / or improve the electrical properties of the plated helicoidal track.

[0206] Figure 6 shows a flow diagram of an alternative method 200 of forming the inductor coil module of Figure 1d.

[0207] The method 200 comprises a first step 201 of providing the tubular frame 2, which in this embodiment involves injection moulding the tubular frame 2 into a tubular form from PEEK and a laser- activated filler material.

[0208] The method 200 further comprises a second step 102 of directing the laser beam 9 onto a portion of the outer surface 3 of the tubular frame 2, the portion of the outer surface 3 of the tubular frame 2 being the helicoidal track 6 circumscribing the cavity 5.

[0209] The method 200 further comprises an optional third step 103 of covering an open end of the tubular frame 2 with the cap, to prevent liquid from entering the cavity 5 of the tubular frame 2.

[0210] In this embodiment, the fourth step 104 of the method 100 of Figure 5 may be omitted, as the laser-activated filler acts as a catalyst once activated by the laser. The method 200 further comprises a fourth step 204 of submerging the outer surface 3 of the tubular frame 2 in the plating solution, to plate the portion 6 of the outer surface 3 with a metal to form an inductor coil circumscribing the cavity 5. In the fourth step, 204, the tubular frame 2 is submerged in the plating solution in the absence of an applied electric potential, such that the plating is achieved by electroless deposition.

[0211] Again, in a further optional step, not shown in Figure 6, the method 200 may further comprise electroplating the plated helicoidal track 6 to increase the thickness and / or improve the electrical properties of the plated helicoidal track.

[0212] For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 5 percent of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

Claims

CLAIMS1 . A method of forming an inductor coil module for an aerosol-generating device, the method comprising: providing a tubular frame having an outer surface and an inner surface, the inner surface defining a cavity for receiving an aerosol-forming substrate when the inductor coil module is in use in an aerosol-generating device; contacting the outer surface of the tubular frame with a plating solution to plate a portion of the outer surface with a metal, wherein a laser beam is directed onto the portion of the outer surface of the tubular frame, the portion of the outer surface of the tubular frame being a helicoidal track circumscribing the cavity; wherein the tubular frame has a longitudinal axis, and the helicoidal track has a pitch that varies along the longitudinal axis of the tubular frame; and wherein the method further comprises electrically connecting a flexible printed circuit to the plated helicoidal track.

2. A method according to claim 1 , wherein the tubular frame is formed from a polymeric material, and preferably wherein the polymeric material comprises at least one of polyetheretherketone (PEEK), liquid crystal polymer (LCP), polysulfone (PSU), polyethersulfone (PES), polyetherimide (PEI) and polyphenylsulfone (PPS).

3. A method according to claim 1 or claim 2, wherein the polymeric material comprises a laser- activated filler that becomes catalytic to electroless metal deposition after exposure to the laser beam, and wherein directing the laser beam onto the portion of the outer surface of the tubular frame activates the laser-activated filler at the portion of the outer surface of the tubular frame, promoting plating of the metal onto the portion of the outer surface of the tubular frame.

4. A method according to any one of claims 1 to 3, wherein the laser beam is directed onto the portion of the outer surface of the tubular frame before the outer surface of the tubular frame is contacted with the plating solution.

5. A method according to any one of claims 1 to 4, wherein the method further comprises the step of contacting the outer surface of the tubular frame with a catalyst solution before contacting the outer surface of the tubular frame with the plating solution.

6. A method according to claim 5, wherein the tubular frame is not formed from a material comprising a laser-activated filler.

7. A method according to any one of claims 1 to 6, wherein the plating solution comprises a source of metal ions, the metal being the metal to be plated onto the outer surface of the tubular frame, and a reducing agent.

8. A method according to any one of claims 1 to 7, wherein the method comprises at least one of: the step of moving the tubular frame relative to the laser beam while the laser beam is being directed onto the outer surface of the tubular frame; and moving the laser beam relative to the tubular frame while the laser beam is being directed onto the outer surface of the tubular frame.

9. A method according to any one of claims 1 to 8, wherein the tubular frame has a longitudinal axis, and wherein the method further comprises the step of rotating the tubular frame about its longitudinal axis while the laser beam is being directed onto the outer surface of the tubular frame.

10. A method according to any one of claims 1 to 9, wherein the tubular frame has a longitudinal axis, and wherein the method further comprises the step of moving the tubular frame along its longitudinal axis while the laser beam is being directed onto the outer surface of the tubular frame.

11. A method according to any one of claims 1 to 10, wherein the tubular frame comprises an open end having an opening for inserting aerosol-forming substrate into the cavity, and wherein the method comprises the step of closing the opening with a cap before contacting the outer surface of the tubular frame with the plating solution.

12. A method according to any one of claims 1 to 11 , wherein a laser beam is directed onto a first portion of the outer surface of the tubular frame and a second portion of the outer surface of the tubular frame, the second portion being separate from the first portion, and wherein the first portion of the outer surface of the tubular frame is a first helicoidal track circumscribing the cavity, and optionally wherein the second portion of the outer surface of the tubular frame is a second helicoidal track circumscribing the cavity.

13. A method according to claim 12, wherein the pitch of the first helicoidal track is different to the pitch of the second helicoidal track14. An inductor coil module for an aerosol-generating device, the inductor coil module being formed by the method of any one of claims 1 to 13.

15. An inductor coil module for an aerosol-generating device, the inductor coil module comprising: a tubular frame formed from a polymeric material, the tubular frame having an outer surface and an inner surface, the inner surface defining a cavity for receiving an aerosol-forming substrate when the inductor coil module is in use in an aerosol-generating device; and an inductor coil circumscribing the cavity, the inductor coil being formed from a metallic helicoidal track deposited on a portion of the outer surface of the tubular frame, wherein the tubular frame has a longitudinal axis, and the helicoidal track has a pitch that varies along the longitudinal axis of the tubular frame; and wherein a flexible printed circuit is electrically connected to the helicoidal track.

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