Heater assembly

Abstract

A method of manufacturing a thin film heater is described. The method includes providing a heating element supported on a surface of a flexible dielectric backing film; and attaching a heat shrink film layer to the surface of the dielectric backing film to at least partially encapsulate the heating element between the heat shrink film and the dielectric backing film. The method provides a more precise and consistent method of assembling a heater assembly and improves thermal performance and heat transfer to a heating chamber.

Description

Technical Field

[0001] The present invention relates to a method of manufacturing a heater assembly, and more particularly to a method of manufacturing a heater assembly for an aerosol generating device. Background Art

[0002] Thin film heaters are used in a wide range of applications that generally require a flexible, low profile heater that can conform to the surface or object to be heated. One such application is in the field of aerosol generating devices, such as reduced risk nicotine delivery products, including e-cigarettes and tobacco vapor products. Such devices heat an aerosol generating substance within a heating chamber to produce a vapor. One means of heating a consumable is to use a heater assembly including a thin film heater that conforms to the surface of the heating chamber to ensure effective heating of the aerosol generating substance within the chamber.

[0003] Thin film heaters typically include a resistive heating element enclosed in a sealed envelope of flexible dielectric film, with contacts to the heating element for connection to a power source, the contacts typically being soldered to exposed portions of the heating element.

[0004] Such thin film heaters are typically manufactured by depositing a layer of metal on a dielectric film support, etching the metal layer supported on the film into the desired heating element shape, applying a second layer of dielectric film to the etched heating element, and heat pressing to seal the heating element with the dielectric film envelope. The dielectric film is then punched to create openings for contacts, which are soldered to the portions of the heating element exposed through the openings.

[0005] These conventional thin film heaters, formed of a planar heating element sealed within an insulating film envelope, must then be attached to the surface to be heated. In the context of an aerosol generating device, this involves attaching the thin film heater to the outer surface of a heating chamber to form a heater assembly so as to transfer heat to an aerosol generating consumable placed within the chamber. Typically, this is achieved by attaching the thin film heater with an adhesive or other fastening means to hold the thin film heater against the heating chamber during use. Other techniques use additional thin film sheets to wrap around the heater assembly to hold the thin film heater against the heating chamber. The thin film heater must then be connected to a power source when assembled into the device.

[0006] Such conventional thin film heaters and heater assemblies have a number of disadvantages. Existing thin film heaters include a large amount of insulating material surrounding the heating element, which results in an increased thermal mass and reduces the efficiency of transferring heat to the heating chamber. Conventional methods of attaching thin film heaters to the heating chamber, involving the application of additional adhesives and / or additional wrapping layers, make this problem worse. The attachment method, which must often be performed manually, is a cumbersome procedure in which it is difficult to securely attach the heater and reliably position the heater in proper alignment relative to the heating chamber. The above problem is particularly important given that the heating element often needs to be precisely placed at a specific location along the heating element to align with the portion of the heating chamber to be heated.

[0007] It is an object of the present invention to make progress towards solving these problems and to provide an improved heater assembly and method of making a heater assembly. Summary of the invention

[0008] According to a first aspect of the invention, there is provided a method of manufacturing a heater assembly, the method comprising: providing a heating element supported on a surface of a flexible dielectric backing film; and attaching a heat shrink film layer to the surface of the dielectric backing film to at least partially encapsulate the heating element between the heat shrink film and the dielectric backing film.

[0009] In this way, the number of film layers is reduced because the heat shrink film layer provides both the function of sealing the heating element with a flexible backing film and the means of attaching the heating element to the heating chamber. Therefore, the thermal mass of the heater assembly is reduced and the heat transfer efficiency is improved. In addition, a secure attachment is provided in a simplified method by the heat shrink film, wherein the sealing and attachment of the heating element can be performed simultaneously. Heat shrinkage provides reliable close contact between the film heater and the heating chamber to ensure effective heat transfer. The method further allows the heater to be accurately placed in the desired position on the heating chamber and attached to the heater at that position before heating to shrink the film. Therefore, the method is improved over other attachment methods (such as using adhesives) that cannot reliably fix the heater in the desired position.

[0010] The term "dielectric" as used to define the backing film should be broadly understood as "electrically insulating".

[0011] The heating element is preferably a flexible heating element, preferably a flexible substantially planar heating element.

[0012] The assembled dielectric backing film, heating element, and heat shrink film layer may be referred to as a thin film heater assembly or subassembly.

[0013] Preferably, the method includes attaching a heat shrink film layer that extends beyond the surface area of ​​the dielectric backing film in one or more directions. This allows the extended portion of the heat shrink to be used to attach the heating element and the supporting backing film to the surface. The heating element may further be aligned relative to the heating chamber by using one of the extended portions, wherein these portions extend beyond the heating element by a predetermined distance.

[0014] Preferably, the heat shrink film layer is attached directly against the heating element. In this way, the heating element is directly sealed between the flexible dielectric backing film and the heat shrink layer, thereby eliminating the need for an additional sealing layer. In other words, the heat shrink provides both a sealing layer and an attachment means.

[0015] Preferably, the heat shrink film layer is attached using an adhesive disposed on the surface of the flexible dielectric layer supporting the heating element. The adhesive may be, for example, a silicon adhesive. The adhesive provides a simple means of reliably fixing the heating element to the backing film. The flexible dielectric backing film may include an adhesive layer, for example, the flexible dielectric backing film may be a polyimide film with a Si adhesive layer. The heating element may be attached by subsequently heating the flexible dielectric backing film, the adhesive layer, and the positioned heating element to bond the heating element to the surface using an adhesive. Subsequent heating may be a heating step for shrinking the heat shrink film to attach the film heater to the heating chamber.

[0016] The backing film can include a polyimide, such as a polyimide film with a Si adhesive layer. Alternatively or in addition, the backing film can include a fluoropolymer, such as PTFE. When the backing film includes a fluoropolymer, it can include a surface layer of at least partial defluorination, which is formed, for example, by surface treatments such as plasma and / or chemical etching. This allows the adhesive to be applied to the treated surface, otherwise the adhesive will not adhere in the case of the extremely low friction surface provided by the fluoropolymer. Additionally or alternatively, the backing film can include PEEK.

[0017] Preferably, the thickness of the flexible dielectric backing film is less than 80 μm, preferably less than 50 μm, and its thickness is preferably greater than 20 μm.

[0018] The heat shrink film may include one or more polyimides, fluoropolymers such as PTFE, and PEEK. The heat shrink film is preferably a preferential heat shrink film arranged to preferentially shrink in one direction. For example, the heat shrink film may be a polyimide 208x tape manufactured by Dunstone. The heat shrink film may be in the form of an initially planar layer, i.e., a piece of heat tape arranged to wrap around the heating chamber, or the heat shrink film may be in the form of a tube arranged to pass around the heating chamber (i.e., to fit over the heating chamber) and heated to shrink the tube to the surface of the heating chamber.

[0019] Preferably, the heating element is a planar heating element comprising: a heater track that follows a circuitous path over the heating area within the plane of the heating element; and two contact feet for connecting to a power source, the contact feet extending away from the heater track in the plane of the heating element. Preferably, the heater track is configured to provide substantially uniform heating over the heating area. The heater track path may be a serpentine or tortuous path over the heating area, and the heater track may have a substantially uniform width and thickness. Preferably, the method comprises: attaching the heat shrink film layer so as to enclose the heater track between the backing film and the heat shrink film layer, leaving the contact feet exposed. In this way, the heater track is electrically insulated between the dielectric backing film and the heat shrink film, while the contact feet are exposed so that they can be connected to a power source.

[0020] When a thin film heater is employed in the device, the contact pin can be long enough to allow direct connection to a power source. For example, the length of the contact pin can be substantially equal to or greater than one or both of the dimensions defining the heating zone. The circuitous path can be configured to leave an empty area within the heating zone.

[0021] Preferably, the attached heat shrink film layer includes an alignment area, which extends beyond the heating element by a predetermined distance in a direction opposite to the extension direction of the contact feet. In particular, the heat shrink film extends beyond the top edge of the heating element. In particular, in an upward direction, i.e., a direction corresponding to the top open end of the heating chamber when attached. By providing an alignment area extending beyond a selected distance of the heating element and / or the backing film, the alignment area can be used to position the heating area of ​​the heater in a desired position. For example, the method may further include aligning the top boundary edge of the alignment area with the end of the heating chamber, and attaching the film heater to the chamber using the heat shrink film. In this way, the heating area is positioned at a known position along the length of the heating chamber from the end of the heating chamber, without having to carefully measure or adjust the heating element to align it correctly. Preferably, the predetermined distance is measured from the side of the heating area opposite to the contact feet to the peripheral edge of the alignment area.

[0022] Preferably, the method further comprises cutting a border portion of the alignment region of the attached heat shrink film so that the distance that the alignment region extends beyond the heater track is reduced to a predetermined distance. In this way, a precise distance can be provided between the edge of the heating region and the edge of the alignment region of the heat shrink so that the heating region can be accurately aligned relative to the edge of the heating chamber. The method may involve positioning and attaching a piece of heat shrink film of a size larger than required and then cutting the heat shrink film after attachment to provide a predetermined distance between the heating region and the peripheral edge of the alignment region. Precision stamping may be used to remove excess border portions of the alignment region.

[0023] Preferably, the attached heat shrink film layer comprises an attachment area extending beyond the flexible backing film. Preferably, the attachment area extends beyond the backing film in a direction substantially perpendicular to the direction of extension of the contact feet. In particular, the heat shrink film may have a width such that it extends beyond the heating element and the flexible dielectric backing film in one or two directions perpendicular to the direction of extension of the heater contact feet. This direction may be referred to as the wrapping direction and is the direction substantially perpendicular to the long axis of the heater chamber when the thin film heater is attached to the heater chamber. The attachment portion of the heat shrink is preferably arranged to extend around the heating chamber when attached to secure the heating element to the heating chamber.

[0024] Preferably, the attachment area of ​​the heat shrink member can extend sufficiently so that it can wrap around the outer surface of the heating chamber circumferentially. For example, the attachment area can extend at least a distance corresponding to the width of the heating area (i.e., the dimension perpendicular to the extension direction of the contact foot).

[0025] The attachment area may be in the form of a tubular portion of a heat shrink that fits around the heating chamber. For example, the heating element and supporting backing film may be wrapped in a tube and fit within a tubular heat shrink tubing. The tubular heat shrink and the tubular film heater therein may then be fit over the heating chamber and heated to secure the film heater to the heating chamber.

[0026] Preferably, the method further includes attaching a temperature sensor to a surface of the flexible dielectric backing film adjacent to the heating element; and attaching the heat shrink layer to the heating element and the temperature sensor. In this way, the temperature sensor can be sealed between the backing film and the heat shrink with the heating element, so that the heating temperature can be accurately measured, and it can be used to control the power provided to the heating element to accurately control the heater. The heater track of the heating element can be shaped to leave a vacant area in or adjacent to the heating area, and the temperature sensor can be placed in the vacant area. The temperature sensor can include a sensor head and a sensor connector (e.g., a wire) for carrying a sensing signal from the sensor head. The sensor head can be positioned between the backing film and the heat shrink, and the connector extends from between the heat shrink and the backing film to be exposed. The temperature sensor can be arranged so that the connecting wire is located near the extended contact foot of the heater element to allow mutual support and / or easy connection to the PCB. The backing film may include a through hole, wherein the temperature sensor head is located on the through hole so as to be exposed on the bottom side of the backing film (the bottom side is the side opposite to the side holding the heating element).

[0027] Preferably, the heat shrink film layer is attached so that an edge region of the flexible dielectric backing layer adjacent to the temperature sensor is exposed, the region comprising adhesive, and the region is folded over the heat shrink film to seal the edge of the heat shrink film adjacent to the temperature sensor. In particular, the heat shrink film can be positioned so that it does not extend to the edge of the dielectric backing film. That is, in a direction opposite to the direction of extension of the attached portion, there may be a peripheral side portion of the backing film that remains exposed, wherein the edge region may carry adhesive. This region may be folded to cover the temperature sensor and seal the edge of the heat shrink film.

[0028] Preferably, the dielectric backing film and the heat shrink film both comprise corresponding through-hole arrangements; wherein the method comprises:

[0029] Positioning the heating element and the dielectric backing film on a positioning fixture, the positioning fixture including a corresponding arrangement of pins, the relative positions of the pins corresponding to the relative positions of the holes of the backing film, such that the pins extend through the holes of the backing film; and positioning the heat shrink film on the heating element and the backing film such that the pins of the positioning fixture enter the holes of the heat shrink film, thereby aligning the heat shrink film with the dielectric backing film. In this way, the heat shrink film can be accurately aligned relative to the backing film and the heating element. The corresponding holes of the backing film and the heat shrink and the corresponding pins of the positioning fixture provide a reference by which the components can be aligned with high precision relative to each other.

[0030] The assembled dielectric backing film, heating element and shrink wrap layer may be referred to as a thin film heater assembly, and preferably the method further comprises: wrapping the thin film heater assembly around the outer surface of the tubular heating chamber, preferably with the dielectric backing film in contact with the outer surface of the heating chamber; and heating the thin film heater assembly to shrink the heat shrink layer, thereby securing the thin film heater assembly against the tubular heating chamber. In this way, the heat shrink film will shrink under heating to secure the thin film heater assembly against the outer surface of the heater chamber. Preferably, the heat shrink material extends sufficiently beyond the dielectric backing film in the wrapping direction so that when wrapped around the heating chamber, the extended portion covers the heater track twice. Preferably, the preferred heat shrink direction of the heat shrink film corresponds to the wrapping direction. The thin film heater is secured to the heating chamber by wrapping a layer of preferential heat shrink tape around the thin film heater to align the preferential heat shrink direction with the wrapping direction, the heat shrink layer shrinking when heated to hold the thin film heater against the heater chamber. Preferably, the thin film heater assembly is wrapped around the heating chamber such that the upper edge of the alignment region is aligned with the top of the heating chamber.

[0031] Preferably, the heating chamber includes one or more recesses in an outer surface, and the thin film heater assembly is positioned relative to the heating chamber such that the temperature sensor attached to the flexible dielectric backing film is positioned within the recesses.

[0032] Preferably, the method further comprises wrapping an additional dielectric film over the attached thin film heater assembly.In some examples, the additional dielectric film may have a lower thermal conductivity than the backing film.

[0033] In another aspect of the invention, there is provided an aerosol generating device manufactured according to a method as defined above or in any one of the appended claims. In particular, there is provided an aerosol generating device comprising: a thin film heater assembly, the thin film heater assembly comprising a heating element and a heat shrink film layer, the heating element being supported on a surface of a flexible dielectric backing film, the heat shrink film layer being attached to the surface of the dielectric backing film to at least partially enclose the heating element between the heat shrink film and the dielectric backing film; and a tubular heating chamber; wherein the thin film heater assembly is fixed against an outer surface of the heating chamber by the heat shrink film. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0035] Figure 1A A thin film heater is presented that includes a heating element supported on a surface of a flexible dielectric backing film;

[0036] Figure 1BA heater assembly manufactured according to the method of the present invention is shown;

[0037] FIG. 2A to FIG. 2H A method of manufacturing a heater assembly according to the present invention is presented;

[0038] Figure 3A and Figure 3B A thin film heater and a heat shrinkable film layer used in a method for manufacturing a heater assembly according to the present invention are respectively shown;

[0039] 4A to 4D A method of manufacturing a heater assembly according to the present invention is presented. DETAILED DESCRIPTION

[0040] FIG1 schematically illustrates a method of manufacturing a heater assembly 100 according to the present invention. The method includes providing a heating element 20 supported on a surface of a flexible dielectric backing film 30; and attaching a layer of heat shrink film 50 to the surface of the dielectric backing film 30 to at least partially enclose the heating element 20 between the heat shrink film 50 and the dielectric backing film 30. The thin film heater assembly 100 can then be directly attached to a surface to be heated, such as the outer surface of a heating chamber of an aerosol generating device. The method provides a more efficient, more accurate and consistent heater assembly method that requires fewer parts. Since the heater assembly 100 requires fewer film layers than conventional approaches, the thermal mass of the heating arrangement is reduced, thereby allowing for more efficient heat transfer to the surface to be heated. In addition, the heater assembly method requires only one heating step to combine the layers and secure the thin film heater assembly 100 to the heating chamber 60.

[0041] like Figure 1A As shown, the first step involves providing a heating element 20, which is supported on the surface of a flexible dielectric backing film 30. This can be achieved in several different ways. In particular, the heating element 20 can be etched from a thin metal sheet of about 50 μm (e.g., a stainless steel sheet such as 18SR or SUS304), but other materials and heater thicknesses can be selected depending on the application. The specific metal and thickness of the metal sheet are selected so that the resulting heating element 20 is flexible so that it can be deformed with the supporting flexible film 30 to conform to the shape of the surface to be heated. The metal sheet can first be deposited on the surface of the flexible dielectric backing film 30, and then etched while supported on the film to form a heater track 21 pattern. Alternatively, the heating element 20 can be etched from the metal sheet independently of the flexible dielectric backing film. For example, a separate metal foil can be chemically etched from both sides to provide one or more connected heating elements 20, which are then separated and positioned on the surface of the dielectric backing film 30.

[0042] The heating element is a planar heating element 20 comprising a heater track 21 which follows a serpentine path over a heating area 22 in the plane of the heating element 20. The heating element has two contact feet 23 to allow connection to a power source, which extend away from the heater track 21 in the plane of the heating element 20. The heater track is preferably shaped to provide substantially uniform heating over the heating area 22. In particular, the heater track is shaped so that it does not contain sharp corners and has a uniform thickness and width, with a substantially constant gap between adjacent portions of the heater track 22 to minimize increased heating at specific points within the heating area 22. In the example of FIG. 1 a, the heater track 21 follows a serpentine path over the heater area 22 and is divided into two parallel track paths 21 a and 21 b, each track path being connected to two contact feet 23. The heater layer 23 may be soldered at a connection point 24 on each contact foot 23 to allow the heater to be connected to a PCB and a power source.

[0043] The flexible dielectric backing film 30 must have suitable properties to provide a flexible matrix to support and electrically insulate the heating element 20. Suitable materials include polyimide, PEEK, and fluoropolymers such as PTFE. In this case, the heating element comprises a heater track pattern 21 etched from a 50 μm stainless steel 18SR layer supported on a single-sided polyimide / Si adhesive film, the adhesive film comprising a 25 μm polyimide film and a 37 μm silicon adhesive layer. The heating element 20 is supported on an adhesive to allow the heating element to be attached to the backing film. Figure 1A The thin film heater 10 may be pre-prepared and stored with a release layer attached to the adhesive surface supporting the heating element 20 to preserve the adhesive layer until it is ready for use. The release layer may be provided, for example, from polyester or a similar material. The release layer may then be peeled off to reveal the sticky adhesive layer supporting the heating element for use. Figure 1B The next assembly step is shown.

[0044] The next key step in the method of manufacturing the heater assembly 100 is to apply a layer of heat shrink film 50 directly onto the surface of the dielectric backing film 30 to at least partially encapsulate the heating element 20 between the heat shrink film 50 and the backing film 30. The heat shrink film 50 may be attached directly to the surface of the heater element 20 with an adhesive to encapsulate the heating area 20 between the backing film 30 and the heat shrink 50. In particular, the heater track 21 is insulated within the sealed envelope formed by the flexible backing film 30 and the heat shrink 50, while the contact pins 23 remain exposed to allow connection to a power source.

[0045] The heat shrink 50 is larger than the backing film 30 and the heating element 20, so that the heat shrink extends beyond the heating element 20 by a predetermined distance in two orthogonal directions 51, 52. This alignment of the heat shrink 50 relative to the heating element 20 allows for later alignment of the heating zone 20 relative to the heating chamber 60. Therefore, careful control of the size of these extensions 51, 52 of the heat shrink at this stage allows the heater assembly 100 to be attached to the heating chamber 60 in a simple manner, providing precise alignment. The relative alignment of the heat shrink and the thin film heater 10 can be achieved in several different ways. The heat shrink 50 can be pre-cut to the correct size and then aligned with the edge of the flexible dielectric backing film 30 to provide the correct predetermined distances 51, 52 of these extensions. Alternatively, as will be described below, specific alignment equipment can be used to achieve this precise alignment.

[0046] The heat shrink 50 extends beyond the heating zone 20 in a direction opposite to the contact foot 23 to provide an alignment region 52 of the heat shrink 50. This alignment region 52 can be aligned with the top edge of the heating chamber 60 so that the heating zone 20 is positioned at a position along the following length of the heating chamber from the top edge of the heater track 21, which length corresponds to the predetermined length 52 of the alignment region. In this way, the heater element 20 can be set at the correct position along the heating chamber 60. The heat shrink 50 also has an attachment region 51 that extends beyond the heater track 21 and the backing film 30 in a direction perpendicular to the extension direction of the contact foot 23 to provide the attachment region 51. The extension direction of the attachment region 51 can be referred to as a "wrapping direction" because this portion of the heat shrink 50 allows it to be wrapped around the tubular heating chamber 60 and then heat shrunk to provide the required tight connection. Similarly, the direction opposite the heater foot 23 in the direction in which the alignment region 52 extends from the heating element 20 can be referred to as the upward or alignment direction, which corresponds to the long axis of the heating chamber 60, pointing toward the top open end. These extension distances 51, 52 can be configured by cutting the heat shrink 50 to the correct size before or after being attached to the surface of the dielectric backing film 30.

[0047] FIG. 2A to FIG. 2H A method of attaching a thin film heater assembly 100 (formed from a heating element 20 supported on a dielectric backing film 30 by an attached heat shrink 50) to the outer surface of a heating chamber 60 is shown. Figure 2A The heat shrink 50 is shown positioned relative to the heating element 20, with the upwardly extending alignment portion 52 and the wrapping portion 51 extending away from the heating element 20 in the wrapping direction 51. The heat shrink film 50 may be attached at this stage by an adhesive disposed on the surface of the backing film 30, or this may be achieved in a subsequent heating step that bonds the heat shrink 50 to the backing film 30.

[0048] Next, if Figure 2B As shown, a temperature sensor 70 is attached to the heater assembly 100 between the flexible backing film 30 and the heat shrink 50. In this case, the temperature sensor 70 is a thermistor having a sensor head 71 configured to detect a local temperature and a temperature sensor connector 72 configured to carry a sensing signal from the sensor head 71 to the PCB. Figure 1A and Figure 2A As most clearly shown in FIG. 1 , the heater track 22 is preferably shaped to leave an empty area 22v within the heating zone 22. The sensor head 71 is positioned in this empty area 22v, between the backing film 30 and the heat shrink 50, so that the sensor head is in close proximity to the heater track 21. By positioning the sensor head 71 in close proximity to the heating element 20, between the heat shrink 50 and the backing film 30, the temperature sensor 70 is sealed in close proximity to the heating element to provide an accurate temperature reading of the heating zone 22. The sensor connector 72 preferably extends in the same direction as the contact pins 23 of the heating element 20, which facilitates the connection of the heater pins 23 and the sensor connector 72 to the PCB.

[0049] like Figure 2A and Figure 2B As shown, the heat shrink member 50 is preferably positioned so that the free edge region 32 of the backing film 30 is exposed. Figure 2C As shown, the free edge region 32 is folded onto the heat shrink film 50 to seal the edge of the backing film 30 and the heat shrink 50. In particular, since the free edge region 32 includes an adhesive on the surface, the free edge region can be used to fold onto the heat shrink 50 to seal the edge region. The free edge region can also be used to fold onto the temperature sensor head 71 to secure it within the fold.

[0050] In the method of FIG. 2 , the next step is to attach two pieces of adhesive tape 35 a, 35 b to attach the assembly to the heating chamber 60 in the correct position before heating the thin film heater assembly 100 to shrink the heat shrink. The adhesive tape 35 a, 35 b can be provided by multiple pieces of polyimide adhesive tape, such as a 0.5 inch polyimide tape having 12.7 microns of polyimide and 12.7 microns of silicone adhesive. The adhesive attachment tape 35 a, 35 b is positioned along each edge of the heat shrink at the end of the wrapping direction. As shown in FIG. Figure 2EAs shown, the film heater 10 can then be attached to the heating chamber 60 by aligning the top edge 53 of the heat shrink 50 with the top edge 62 of the heating chamber 60. Assuming the distance 52 of the alignment area is carefully selected, this alignment step allows the heating area 22 to be placed at the correct location along the heating chamber 60. Some consumables will contain a certain amount of aerosol generating material at a specific location, so it is important that the correct part of the heater chamber is heated to effectively release vapor from the consumable.

[0051] First, the thin film heater assembly 100 is attached to the heating chamber using adhesive tape 35a. The heating chamber 60 is a tubular heating chamber that is arranged to accommodate consumables to be heated to produce vapor for inhalation by the user. The heating chamber 60 preferably has one or more recesses 61 on the outer surface, which provide internal protrusions that help to position the consumables received in the chamber 60 and transfer heat to them. The circumference of the heating chamber 60 preferably closely matches the width of the heating element 20 (the length in a direction perpendicular to the direction in which the contact foot extends) so that the heating element provides a complete circumferential ring around the chamber 60. In other examples, the size of the heater element can be determined to be greater than the circumference of the heating chamber once, that is, the size of the heating element can be determined to provide an integer number of circumferential rings around the heating chamber, so that no changes in the heating temperature are generated around the heating chamber. The thin film heater assembly 100 is positioned and attached so that the temperature sensor head 71 is located within the recess 61 on the outer surface of the heating chamber 60 to provide a more accurate reading of the internal temperature of the heating chamber 60 .

[0052] Once attached with the first adhesive tape portion 35a, the thin film heater assembly 100 is then wrapped around the heating chamber 60, with the extended attachment portion 51 of the heat shrink 50 wrapped circumferentially around the chamber 60 to again cover the heating element 20, and then attached by the second piece of attachment tape 35b to provide Figure 2F Attached heater assembly 110 (including heater element 20, backing film 30, heat shrink film 50, thermistor 70, and heater chamber 60) is shown in FIG. Since the length of attachment area 51 is substantially the same as the length of heating area 22 (and the perimeter of heating chamber 60), attachment portion 51 is wrapped once to cover heating area 22, so that Figure 2F The two layers of heat shrink film in the attached heater assembly 110 insulate the heater element. The attachment area can be sized to provide more than one additional coverage of the heating element 20. For example, the attachment area 51 can extend beyond the heating element by a distance corresponding to an integer multiple of the outer perimeter of the heating chamber 60.

[0053] As in Figure 2FAs can be seen in FIG. 1 , the temperature sensor connector 72 and the heater foot 23 are positioned so that they are aligned after this quick step to facilitate connection to the PCB. Figure 2G As shown, the attached heater assembly 110 is heated to fit the heat shrink 50 against the heating chamber 60. For example, the assembly 110 can be heated in an oven at about 210°C for ten minutes to shrink the film, although the time and temperature can be adjusted for other types of heat shrinks. This process allows a large number of units to be heat treated simultaneously in a small oven. This is the only heating step that can simultaneously seal the thin film heater to the heating chamber and bond the backing film to the heat shrink.

[0054] Finally, although not required, a final dielectric film layer 36 may be added around the outside of the heating element to complete the Figure 2H The heating assembly shown. The final dielectric layer can be, for example, an additional adhesive polyimide layer, such as a 1-inch polyimide tape with 25 microns of polyimide and 37 microns of silicon adhesive. The external dielectric film layer 36 provides an additional insulating layer and further ensures the attachment of the thin film heater to the heating chamber 60. The thickness and / or material of the backing film 30, the heat shrink 50 and the final insulating layer 36 can be selected to enhance heat transfer to the heating chamber, such as setting the layer with lower thermal conductivity (i.e., the heat shrink 50 and the insulating layer 36 in this example) on the outside of the heating element and setting the layer with higher thermal conductivity as the backing film. Once the external insulating dielectric film layer 36 has been applied, the assembly 110 can be heated again. This second heating step allows further degassing of the external dielectric film layer 36 and other layers. For example, in the second heating stage, the heating temperature can be increased to a higher temperature than the heat shrink stage, closer to the operating temperature of the device. This allows further degassing of, for example, Si adhesive, which may not occur during the heat shrink step at a lower temperature. During first use of the device, it may also be beneficial to expose the heat shrink to a temperature closer to the operating temperature prior to heating.

[0055] 3 and 4 illustrate another optimized method of manufacturing a heater assembly according to the present invention, which includes several additional features that facilitate accurate alignment of the heat shrink film 50 relative to the heating element 20 and the backing film 30. In this method, as Figure 3A and Figure 3B As shown, a series of alignment holes 34 , 54 are provided in both the backing film 30 and the heat shrink 50 , which can be used for relative alignment of the backing film 30 and the heat shrink 50 .

[0056] Figure 3AThe thin film heater 10 is schematically illustrated in which the first step of providing a heating element 20 on the surface of a flexible dielectric backing film 30 has been performed. The thin film heater 10 differs from the previous embodiment in that the backing film 30 is provided with a number of alignment holes 34a, 34b, 34c, 34d, which are positioned in the backing film to be arranged around the heating element 20. In particular, in this example, the backing film 30 includes two alignment holes 34a, 34b, which are arranged along the top edge of the backing film 30 so as to be positioned above the heating element 20 when it is attached to the backing film 30. Two additional alignment holes 34c, 34d are arranged below the heating area 22 of the heating element 20. The thermistor hole 37b discussed below can provide additional alignment holes in some examples. Similarly, the heat shrink film 50 has a corresponding number of alignment holes 54, which correspond in relative position to those alignment holes 34 of the backing film 30. The alignment holes 34, 54 are arranged so that when the holes in the backing film 30 begin to align with the alignment holes 54 of the heat shrink 50, the heat shrink 50 is precisely positioned in the correct position relative to the thin film heater 10 so that the heat shrink 50 extends the correct length 51, 52 beyond the heating area 22 to allow the heating element 20 to be precisely aligned relative to the heating chamber 60 when attached.

[0057] The flexible dielectric backing film 30 has two further holes 37a, 37b over which the thermistor sensor head 71 is positioned so as to expose the temperature sensing head 71 of the thermistor 70 through the backing film 30, as will be described in more detail below. As with the previous examples, the backing film 30 may be any suitable flexible electrically insulating material, for example a fluoropolymer such as PTFE, PEEK or polyimide. In this case, the backing film 30 is provided by a 25 μm polyimide film with a 40 μm silicone adhesive layer on which the heating element 20 is supported. The holes 34, 54 may be of any suitable size, in this case 1 mm, so that they can be used in conjunction with the alignment pins on the alignment fixture to co-locate the alignment holes 34 of the backing film with the alignment holes 54 of the heat shrink 50.

[0058] 4 illustrates a method of preparing a thin film heater assembly 100 ready for attachment to a heating chamber 60. As described above, the heating element 20 is first disposed on the adhesive surface of the flexible dielectric backing film 30 so as to position the heating element between the alignment holes 34 of the dielectric backing film 30. The heating element 20 is substantially as described above, however two 1 mm holes 25 are provided in the solder 24 on the heating foot 23 to enhance soldering strength when the heating element contact foot 23 is attached to the PCB.

[0059] The first step in the process is to first Figure 4BThermistor 70 is attached as shown. Figure 4A and Figure 4B As can be clearly seen, the flexible dielectric backing film 30 further comprises a foldable portion 38 in the form of a tab 38 formed by two cuts in the backing film, allowing the tab 38 to be folded onto itself into the vacant area 22v, where the thermistor 70 is positioned. In this example, the tab 38 is in a mid-position along the free edge area 32, but it could equally well be formed by one cut to provide a bottom portion of the free edge area that can be folded onto the thermistor 20 when positioned. In this example, the tab 38 comprises a thermistor hole 37b that is aligned with a thermistor hole 37a provided in the flexible dielectric backing film 30, which is in the vacant area 22v left by the shape of the heating track 21. The thermistor hole 37b is not necessary, and the tab 38 can be an uninterrupted surface portion that does not contain a hole, so that the tab is folded onto the thermistor, the thermistor being visible only through the thermistor hole 37a. In some examples, thermistor hole 37b may also be used for alignment with the positioning fixture 80. Thermistor sensor head 71 is positioned on thermistor hole 37a in the vacant area 22v of the backing film 30 so that the sensor head is exposed to the opposite side of the thin film heater through the backing film 30. Since the thin film heater is attached to the heating chamber 60 in direct contact with the backing film, thermistor hole 37a allows thermistor sensor head 71 to be in direct contact with the heating chamber 60.

[0060] The backing film tab 38 is then folded over the thermistor 70 so that the thermistor hole 37b (if present) is aligned with the thermistor hole 37a and attached via the silicone adhesive provided on the attachment surface of the backing film 30. In this manner, the thermistor is attached to the backing film with the sensor head 71 attached between the backing film 30 and the folded tab 38 of the backing film, which is glued in place, and the thermistor connection 72 extending in a direction generally corresponding to the direction of the heater contact foot 23. This process is used to first attach the thermistor 70 in place before aligning and attaching the heat shrink 50 to the thin film heater 10.

[0061] The heat shrink 50 is then aligned relative to the film heater 10 using a positioning fixture 80. The positioning fixture 80 includes a support surface 82 having four upstanding alignment pins 81 that correspond in their relative displacement to the positions of the alignment holes 34, 54 on the backing film 30 and the heat shrink 50. The film heater 10 (including the heating element 20 on the backing film 30) is first positioned on the surface of the alignment fixture 80 so that the alignment pins 81 extend through the backing film alignment holes 34. The heat shrink 50 is then positioned on the film heater 10 so that the pins 81 further extend through the alignment holes 54 of the heat shrink 50. This process ensures that the heat shrink 50 is accurately aligned relative to the heating element 20 and the backing film 30. In particular, when the alignment holes 34 and 54 are aligned, this positions the heat shrink so that the heat shrink 50 extends beyond the heating element 20 in the direction opposite to the contact foot to provide a specific predetermined length of the alignment portion 52 and a specific predetermined extension length of the wrap portion 51.

[0062] Once the heat shrink member 50 is Figure 4C and Figure 4D If it is correctly positioned as shown, Figure 4D As shown, the edge area 32 of the backing film 30 that was left open by the positioning of the heat shrink 50 is folded over the top of the heat shrink to seal the edge of the backing film 30 and the heat shrink 50 layer. This secures the heat shrink 50 to the backing film 30 and additionally secures the thermistor connector 72 in place. Then, as described above with reference to Figures 2E to 2H As stated, Figure 4D The assembled thin film heater subassembly 100 shown can be attached to the heating chamber 60. In particular, by aligning the top edge 53 of the heat shrink 50 with the top edge 62 of the heating chamber 60, the heating area provided by the heating track 22 is positioned at a desired point on the heating chamber 60 to provide effective heating to the consumables received in the chamber 60. The thin film heater subassembly 100 can be wrapped around the chamber as shown. Figure 2E The thin film heater assembly 100 is sealed to the heating chamber 60 by heating to shrink the heat shrink 50 and thereby secure the heater against the outer surface of the heating chamber 60.

[0063] As described above, it is important to ensure a precise distance between the top edge 53 of the heat shrink layer and the heating track 21 so that the heating area 22 can be reliably positioned on the heating chamber. Because the flexible backing film is thin and soft, it may undergo stretching deformation during assembly of the heater assembly 100, which may change the specified distance of the alignment area 52. In order to ensure that the predetermined distance 52 is provided reliably and repeatably, the method may further include several additional steps to ensure this. First, make the heat shrink member 50 slightly longer in the vertical alignment direction (the direction opposite to the extension direction of the contact feet 23 when attached to the backing film). For example, the length of the heat shrink film 30 can be increased by 1mm. The distance between the top of the heater track 21 and the top of the heat shrink film will then be 1mm larger than the dimension required to set the heater track 21 in the correct position. Once such Figure 4D The heat shrink is shown attached, for example, using a precision punch to punch out the heat shrink layer 50, to cut the heat shrink to size and remove excess. In this way, if the heat shrink has been deformed or moved during the initial assembly step, this subsequent cutting step ensures the accuracy of the distance between the heater track 21 and the top edge 53 of the heat shrink 50, which can provide an accuracy of about 0.3 mm, which is sufficient to achieve accurate placement of the heater zone 22.

[0064] As described above, the thermistor is placed with the sensor head in the thermistor hole 37a, and the hole 37b in the tab 38 of the backing film 30 is folded over the sensor head 71. This ensures that the thermistor is always accurately positioned relative to the heating element 20, and it also means that the sensor head 71 of the thermistor 70 is in direct contact with the outer surface of the heating chamber 60, so there is no intervening insulating material, thereby improving the accuracy of the temperature reading provided by the thermistor 70.

[0065] Once the heat treatment has been performed to shrink the heat shrink film 50 to secure the heating element, the thermistor connector 72 and the heated contact pins 23 can then be used in a heating device such as an aerosol generating device by attaching the thermistor connector 72 and the heated contact pins 23 to a PCB and a power source. Figure 2G and Figure 2H The heater subassembly 110 is shown. The assembly method according to the present invention reduces the number of assembly steps compared to known methods, thereby providing a more efficient and cost-effective assembly method. Importantly, the number of insulating film layers is reduced because the heat shrink 50 provides both an insulating layer and a means of attaching the thin film heater 10 to the heating chamber 60. Therefore, the thermal performance of the heater assembly 110 is improved and the heat transfer efficiency is increased. The method of aligning the thin film heater assembly 100 relative to the heating chamber 60 using the extended portion of the heat shrink 50 also provides a more accurate and consistent method of assembling the heater assembly to provide heating at the desired location on the heating chamber 60.

Claims

1. A method of manufacturing a heater assembly, comprising: providing a heating element supported on a surface of the flexible dielectric backing film; attaching a heat shrink film layer to the surface of the dielectric backing film to at least partially enclose the heating element between the heat shrink film layer and the dielectric backing film, wherein the heating element is a planar heating element comprising: a heater track that follows a circuitous path over a heating area in the plane of the heating element; and two contact feet for connecting to a power source, the contact feet extending away from the heater track in the plane of the heating element; wherein the method comprises: attaching the heat shrink film layer so as to enclose the heater track between the dielectric backing film and the heat shrink film layer, leaving the contact feet exposed, and wherein the attached heat shrink film layer includes an alignment region extending a predetermined distance beyond the heating element in a direction opposite to the direction in which the contact feet extend; and The heating element is attached to the heating chamber with the heat shrink film layer.

2. The method of claim 1, wherein: The method includes attaching a heat shrink film layer that extends beyond the surface area of ​​the dielectric backing film in one or more directions.

3. The method according to claim 1 or 2, wherein: The heat shrink film layer is attached using an adhesive disposed on the surface of the dielectric backing film that supports the heating element.

4. The method of claim 1, further comprising the steps of: The boundary portion of the alignment area of ​​the attached heat shrink film layer is cut so that the distance by which the alignment area extends beyond the heater track is reduced to a predetermined distance.

5. The method according to claim 1 or 4, wherein: The attached heat shrink film layer includes an attachment area extending beyond the dielectric backing film in a direction substantially perpendicular to the extension direction of the contact feet.

6. The method of claim 1 or 2, further comprising: attaching a temperature sensor to a surface of the dielectric backing film adjacent to the heating element; as well as The heat shrink film layer is attached to the heating element and the temperature sensor.

7. The method of claim 6, wherein: The heat shrink film layer is attached so that an edge region of the dielectric backing film proximate to the temperature sensor is exposed, the edge region includes adhesive, and the region is folded over the heat shrink film layer to seal the edge of the heat shrink film layer proximate to the temperature sensor.

8. The method of claim 6, wherein: The dielectric backing film includes a through hole in a region adjacent to the heating element, the method further comprising: The temperature sensor is attached such that the temperature sensor is located over the through hole.

9. The method according to claim 1 or 2, wherein: The dielectric backing film and the heat shrink film layer both include corresponding through-hole arrangements; wherein the method comprises: positioning the heating element and the dielectric backing film on a positioning fixture, the positioning fixture including pins whose relative positions correspond to the relative positions of the holes of the dielectric backing film such that the pins extend through the holes of the dielectric backing film; and The heat shrink film layer is positioned over the heating element and the dielectric backing film such that the pins of the positioning fixture enter the holes of the heat shrink film layer, thereby aligning the heat shrink film layer with the dielectric backing film.

10. The method according to claim 1 or 2, wherein: The assembled dielectric backing film, the heating element and the heat shrink film layer form a thin film heater assembly; the method further comprises: wrapping the thin film heater assembly around an outer surface of a tubular heating chamber, the dielectric backing film being in contact with the outer surface of the heating chamber; and The thin film heater assembly is heated to shrink the heat shrink film layer, thereby securing the thin film heater assembly against the tubular heating chamber.

11. The method of claim 10, wherein: The method comprises the steps of claim 1, and further comprises: When wrapping the thin film heater assembly around the heating chamber, the alignment region of the heat shrink film layer is used to align the thin film heater assembly with the heating chamber.

12. The method of claim 10, wherein: The heat shrinkable material includes a material that shrinks preferentially along a preferential shrinking direction when heated; wherein the heat shrinkable film layer is arranged so that the preferential shrinking direction corresponds to the wrapping direction.

13. A heater assembly manufactured using the method of any preceding claim.

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