Inductors made from bundled fibers and components, systems, and methods

Abstract

A core for an inductor includes a plurality of axial fibers and an electrically insulating material disposed between the fibers. The core can be integrated into an inductor, transformer, or other electrical component. A method of manufacturing a core includes forming an insulating fiber or a bundle of insulating fibers.

Description

Cross-reference to related applications

[0001] This application claims priority and benefit to U.S. Provisional Application No. 63 / 594,923, filed October 31, 2023, entitled “INDUCTOR, MADE FROM BUNDLEDFIBERS, AND COMPONENTS, SYSTEMS AND METHODS,” which is incorporated herein by reference in its entirety. Technical Field

[0002] This disclosure relates to cores that can be used in inductors and other electrical devices, devices including such cores, and methods for manufacturing and using such cores. More specifically, this disclosure relates to cores formed of multiple fibers. Background Technology

[0003] Inductors can be formed from a core and conductive structures adjacent to the core (e.g., one or more windings). When current flows through the conductive structures, eddy currents are generated in the core due to electromagnetic properties. These eddy currents cause losses (e.g., heat), which worsen at high frequencies such as 40 MHz or higher. Therefore, there remains a need for core structures that can minimize eddy current losses while maintaining material density. Summary of the Invention

[0004] According to embodiments of this disclosure, a core for an inductor includes a plurality of axially arranged fibers and an electrically insulating material disposed between the fibers. The fibers may be formed of a metal or metal oxide, such as a ferromagnetic material. The plurality of fibers may be transverse to a magnetic field within the core. Devices employing this core may further include conductive structures adjacent to the core. The device may be, for example, an inductor or a transformer.

[0005] A method of manufacturing a core includes: providing an insulating wire formed of an electrically insulating material wound around a metal structure, wherein the metal structure comprises metal wire or compacted metal powder and is formed of a metal or metal oxide; and drawing the insulating wire to form insulating fibers comprising continuous fibers with a diameter of 100 nm to 10 µm and an electrically insulating material coating disposed around the fibers. The method further includes: combining a plurality of insulating fibers such that they are axially aligned. The insulating fibers may be combined during or after the drawing process. Attached Figure Description

[0006] Various embodiments of this disclosure can be more fully understood through the detailed description and accompanying drawings provided below. In the drawings, similar reference numerals may denote the same or functionally similar elements. Embodiments are described in detail below with reference to the accompanying drawings, in which:

[0007] Figure 1 This is a perspective view of an inductor according to an embodiment of the present disclosure.

[0008] Figure 2A This is a cross-sectional view of the core according to an embodiment of the present disclosure.

[0009] Figure 2B yes Figure 2A A magnified view of a portion of the image.

[0010] Figure 3A This is a cross-sectional view of the core according to an embodiment of the present disclosure.

[0011] Figure 3B yes Figure 3A A magnified view of a portion of the image.

[0012] Figure 4A This is a cross-sectional view of the core according to an embodiment of the present disclosure.

[0013] Figure 4B yes Figure 4A A magnified view of a portion of the image.

[0014] Figure 5A This is a cross-sectional view of the core according to an embodiment of the present disclosure.

[0015] Figure 5B yes Figure 5A A magnified view of a portion of the image.

[0016] Figure 6A This is a cross-sectional view of the core according to an embodiment of the present disclosure.

[0017] Figure 6B yes Figure 6A A magnified view of a portion of the image.

[0018] Figure 7A This is a cross-sectional view of the core according to an embodiment of the present disclosure.

[0019] Figure 7B yes Figure 7A A magnified view of a portion of the image.

[0020] Figure 8A This is a cross-sectional view of the core according to an embodiment of the present disclosure.

[0021] Figure 8B yes Figure 8A A magnified view of a portion of the image.

[0022] Figure 9 This is a perspective view of an inductor according to an embodiment of the present disclosure.

[0023] Figure 10 This is a perspective view of an inductor according to an embodiment of the present disclosure.

[0024] Figure 11 This is a perspective view of an inductor according to an embodiment of the present disclosure.

[0025] Figure 12A This is a perspective view of an inductor according to an embodiment of the present disclosure.

[0026] Figure 12B yes Figure 12A Cross-sectional view of the inductor along line AA

[0027] Figure 12C yes Figure 12A A three-dimensional diagram of the conductive structure of an inductor.

[0028] Figure 13 This is a perspective view of a transformer according to an embodiment of the present disclosure.

[0029] Figure 14 This is a block diagram of a buck converter that can employ an inductor according to an embodiment of the present disclosure.

[0030] Figure 15 This is a flowchart of a method for manufacturing a chip according to an embodiment of the present disclosure.

[0031] Figure 16 It is a diagram depicting the relationship between coercivity and saturation polarization of various materials.

[0032] Figure 17 It is a graph depicting the relationship between coercivity, saturation polarization, and cost of various materials.

[0033] Figure 18 It is a graph depicting the relationship between the magnetic permeability and saturation polarization of various materials. Detailed Implementation

[0034] Although the claimed subject matter will be described based on certain implementations and examples, other implementations and examples, including those that do not provide all the benefits and features described herein, are also within the scope of this disclosure. Various structural, logical, and process changes may be made without departing from the scope of this disclosure.

[0035] To reduce eddy current losses, inductor cores are formed from laminated layers of magnetic material (laminated cores) or compacted magnetic powder (dust cores). Both approaches aim to reduce eddy current size by dividing the core into multiple isolated regions. However, the thinnest laminated core layer is approximately 10 µm thick, making it unsuitable for very high frequency (VHF) applications. While dust cores can include particles as small as 1 µm, they suffer from lower magnetic material density and lower permeability. Furthermore, it is difficult to mass-produce the high-purity and uniform magnetic nanoparticles required for dust cores and subsequently fabricate them into uniformly dispersed and high-density compacts (e.g., compacted layers). The resulting inhomogeneities degrade the performance of dust cores in inductors. Conversely, embodiments of this disclosure provide cores formed from very fine, uniformly arranged fibers (100 nm to 10 µm) that achieve excellent performance in inductors or other devices, even at frequencies up to 100 MHz.

[0036] Reference Figure 1 An inductor 100 according to embodiments of the present disclosure includes a core 20 formed by a plurality of axially arranged fibers 10. The plurality of fibers 10 may be arranged transversely to a magnetic field B within the core 20. In some embodiments, the plurality of fibers 10 are arranged perpendicularly to the core 20. In some embodiments, each fiber 10 may have an aspect ratio of at least 3, at least 5, or at least 10.

[0037] In some embodiments, the cross-sectional shape of fiber 10 is circular, rectangular, triangular, hexagonal, or a combination thereof. For example, Figure 2A and 2B The core 20a includes fibers 10a having a circular cross-sectional shape. Figure 3A and 3B The core 20b includes fibers 10b having a hexagonal cross-sectional shape. Figure 4A and 4B The core 20c includes fibers 10c having a square cross-sectional shape. Figure 5A and 5B The core 20d includes fibers 10d with a triangular cross-sectional shape. Other cross-sectional shapes can be used, such as oval or regular or irregular polygons.

[0038] In some embodiments, fiber 10 has a uniform cross-sectional shape. In other embodiments, core 20 may include a first plurality of fibers having a first cross-sectional shape and a second plurality of fibers having a second cross-sectional shape different from the first cross-sectional shape. In such embodiments, the first plurality of fibers and the second plurality of fibers may be randomly distributed or distributed in a predetermined pattern, or they may be separated within core 20.

[0039] In one or more embodiments, fiber 10 is formed of a material with a magnetic permeability higher than that of air. In some embodiments, fiber 10 is formed of metal and / or metal oxide. In some embodiments, fiber 10 is formed of ferromagnetic or ferrimagnetic material. In some embodiments, fiber 10 is formed of soft magnetic material. Magnetic materials can generally be divided into two main categories: soft and hard. Hard magnetic materials have high coercivity and are suitable for permanent magnets, while soft magnetic materials have low coercivity and are suitable for inductors, transformers, etc. Typically, soft magnetic materials can be classified based on chemical composition (e.g., NiFe, soft magnetic ferrite, SiFe, CoFe, or variants within the Fe class) and / or based on atomic structure (i.e., nanocrystalline, amorphous, polycrystalline, etc.). Various materials in the amorphous and nanocrystalline categories are generally suitable for forming fiber 10, provided that the manufacturing challenges associated with brittleness can be overcome. The properties of some materials that can be used for fiber 10 are summarized in Table 1 below.

[0040] Table 1

[0041] In some embodiments, the material of fiber 10 is selected based on the following criteria: high saturation (e.g., greater than 1), low coercivity (e.g., less than 10 A / m), and high relative permeability (e.g., greater than 1000). In some embodiments, the material is selected to satisfy the above-mentioned coercivity and permeability ranges and to maximize saturation (e.g., at least 1.5, at least 2, or greater than 2). In contrast, maximizing the permeability of the material (e.g., greater than 100,000) may result in diminishing returns. Figures 16 to 18 The relationship between the saturation of various magnetic materials and their coercivity, cost, and / or permeability is depicted.

[0042] According to some embodiments, the fiber 10 comprises a nanocrystalline and / or amorphous soft magnetic material. In some embodiments, the fiber 10 comprises materials selected from NiFe (e.g., Ni...). 50 Fe 50 Ni 48 Fe 52 Ni 56 Fe 44 or Ni 80 Fe 20 ), SiFe, CoFe (e.g., Co) 50 Fe 50 Ferrous alloys of or combinations thereof.

[0043] In some embodiments, the fibers 10 are homogeneous in composition. In other embodiments, the core 20 may include a first plurality of fibers made of a first material and a second plurality of fibers made of a second material different from the first material. In such embodiments, the first plurality of fibers and the second plurality of fibers may be randomly distributed or distributed in a predetermined pattern, or they may be separated within the core 20. For example, Figure 8A and Figure 8B The core 20k depicted includes a first fiber 10k and a second fiber 10m formed of different materials and arranged in alternating rows.

[0044] According to embodiments of this specification, the diameter of fiber 10 is from 100 nm to 10 µm. In some embodiments, the diameter of fiber 10 is at least 100 nm, at least 200 nm, at least 300 nm, at least 400 nm, at least 500 nm, at least 700 nm, at least 1 µm, or at least 2 µm and at most 10 µm, less than 10 µm, at most 8 µm, at most 5 µm, at most 3 µm, at most 2 µm, at most 1 µm, or at most 500 nm. It should be understood that the fiber diameter can be within any logical combination of the aforementioned lower and upper limits, for example, in the range from 200 nm to 5 µm or from 1 µm to 8 µm. In some embodiments, fiber 10 may have a uniform diameter or a substantially uniform diameter (e.g., a variation of no more than 10% or no more than 20%). In other embodiments, core 20 may include a first plurality of fibers having a first diameter and a second plurality of fibers having a second diameter different from the first diameter. In such an implementation, the first plurality of fibers and the second plurality of fibers can be randomly distributed or distributed in a predetermined pattern within the core 20, or they can be separated within the core 20. For example, Figure 6A and Figure 6B The core 20e shown includes a first fiber 10e having a first diameter, a second fiber 10f having a second diameter smaller than the first diameter, and a third fiber 10g having a third diameter smaller than the second diameter. Compared to a structure with circular fibers of uniform diameter, Figure 6A and Figure 6B The pattern shown provides a denser stacking of fibers 10e, 10f, and 10g.

[0045] In some embodiments, the core 20 may include fibers 10 of different diameters and compositions. In such embodiments, the different fibers 10 may be randomly distributed or distributed in a predetermined pattern, or they may be separated within the core 20. For example, Figure 7A and Figure 7BThe depicted core 20h includes a first fiber 10h having a first diameter and formed of a first material, a second fiber 10i having a second diameter smaller than the first diameter and formed of a second material different from the first material, and a third fiber 10j having a third diameter smaller than the second diameter and formed of a third material different from the first and second materials.

[0046] In some embodiments, the core 20 may include fibers 10 with different diameters, compositions, and cross-sectional shapes.

[0047] Back Figure 1 The core 20 also includes an electrically insulating material 12 disposed between the fibers 10 to electrically insulate them from each other. The composition of the insulating material 12 is not particularly limited and may include resin materials. The thickness of the insulating material 12 should be sufficient to electrically insulate the fibers 10. Generally, as the fiber diameter decreases, the relative amount of insulating material 12 in the core 20 will increase.

[0048] Inductor 100 includes a conductive structure 30 adjacent to core 20. Figure 1 In this context, the conductive structure 30 is a conductive wire wound around the core 20. For example, as... Figure 9 As shown, inductor 900 includes a toroidal core 920 formed of a plurality of fibers 210, having a conductive structure 930 (winding) wound around the toroidal core 920. In some embodiments, the conductive structure 930 may include two or more windings (e.g., as in a coupled inductor), wherein the coupling factor of each winding may be different. The shape, composition, and construction of the conductive structure 930 are not particularly limited. For example, Figure 10 and Figure 11 Alternative constructions of conductive structures 1030 and 1130 are depicted; these are solid shaped components rather than wires. Figure 10 and Figure 11 In the inductors 1000 and 1100, conductive structures 1030 and 1130 are disposed around cores 1020 and 1120, which are formed of multiple fibers 1010 and 1110, respectively.

[0049] During operation, current flows through conductive structure 30, generating a magnetic field. This magnetic field penetrates core 20 and is amplified or altered (e.g., concentrated or redirected) by a magnetic field B induced within core 20. In some embodiments, the structure and / or orientation of fiber 10 provides improved properties, such as reduced eddy current losses. Furthermore, the density of fiber 10 within core 20 can be controlled, for example, by selecting the material, shape, and / or size of fiber 10, selecting the material and / or thickness of insulating material 12, and / or by process conditions (e.g., compacting core 20 under a predetermined pressure). By controlling the density of the fiber material within core 20, the permeability of core 20 can also be controlled.

[0050] Although the toroidal core shape has been discussed above, this disclosure is not limited to a particular core shape. The core 20 disclosed herein may be, for example, rectangular or E-shaped, or may include distributed air gaps. Figure 12A An example of an alternative core shape is shown, wherein the linear inductor 1200 includes a core 1220 formed of a plurality of fibers 1210 arranged around a conductive structure 1230. Figure 12B and Figure 12C Another view is shown. In this embodiment, at least a portion of the conductive structure 1230 passes through the core 1220. As described above, the fibers 1210 are axially aligned and are transverse to or perpendicular to the magnetic field B2 of the core 1220.

[0051] The core described herein can be used in various electrical devices, such as the inductor (or transformer) described herein (e.g., used in electronic devices such as computers, mobile phones, or any other type of electronic equipment). In some implementations, such as Figure 13 As shown, the core can be included in the transformer. Figure 13 In the transformer 1300, there are a primary winding 1330 and a secondary winding 1332, which are wound on a core (not shown, as it is below the winding).

[0052] In some implementations, the core may be integrated into an inductor, and one or more of the inductors may be included in a circuit. For example, Figure 14 A buck converter 1410 (e.g., within an electronic device 1400) comprising two inductors L1 and L2 is depicted, each of which may be an inductor 100, 200, 300, 400, or 500. In some embodiments, the core may be integrated into an induction-based power converter, such as a boost converter or a buck-boost converter. In some embodiments, the core may be integrated into a charge pump, for example, in an inductor coupled to the charge pump.

[0053] Reference Figure 15This document also discloses a method 1500 for forming a core. Method 1500 includes a step 1510 of forming a metal wire. The metal may be, for example, a solid wire or compacted metal powder, and the composition of the metal may include metals, metal oxides, materials disclosed above with reference to fiber 10, or combinations thereof. After or simultaneously with forming the metal wire in step 1510, method 1500 includes a step 1520 of insulating the metal wire within an electrically insulating material. The insulating material may be as described above, and in some embodiments is a resin. In some embodiments, the insulating material may be present as a coating or sheathing around the metal wire.

[0054] Next, method 1500 includes a step 1530 of drawing insulated metal wires into insulated fibers. The drawing step 1530 can be performed at elevated temperatures, for example, at least 100 °C, at least 200 °C, at least 300 °C, or about 300 °C. The drawing can be performed in stages, each stage further reducing the fiber diameter. The drawing step 1530 results in fibers having the diameter and cross-sectional shape described above. Furthermore, the resulting insulated fibers have a solid, continuous metal core and an insulating material coating or sheath disposed therearound. This is true even when the starting metal wire material includes metal particles or powder. The drawing step 1530 can include drawing individual insulated metal wires to obtain a single insulated fiber, or drawing a bundle containing multiple insulated metal wires to obtain a bundle of insulated fibers.

[0055] Finally, method 1500 includes step 1540 of forming a core from a plurality of insulating fibers. In some embodiments, step 1540 includes aggregating individually drawn insulating fibers or a bundle of insulating fibers drawn together. The aggregating includes axially aligning the insulating fibers and may include compacting the insulating fibers or the fiber bundle. In some embodiments, the drawing step 1530 provides a bundle of insulating fibers comprising a sufficient number of fibers to form a core. In some embodiments, step 1540 includes cutting a plurality of insulating fibers in the transverse direction of the fibers to provide a desired fiber length (corresponding to core thickness or length). In some embodiments, step 1540 includes cutting a plurality of insulating fibers in the axial direction of the fibers to provide a core shape, such as those described above. In other embodiments, step 1540 may include an extrusion process to provide the desired core shape. In still other embodiments, step 1540 may include a molding step combined with aggregating to compress the insulating fibers into the desired core shape.

[0056] In some embodiments, step 1540 involves combining insulating fibers with different compositions, cross-sectional shapes, and / or diameters to provide as described above. Figures 2A to 8BThe core is described above. In other embodiments, a change in fiber type may be a result of the drawing step 1530. For example, the drawing step 1530 may include bundling insulated metal wires with different compositions together and drawing them together.

[0057] This document describes a device. The device includes a core and an adjacent conductive structure. The core includes a plurality of fibers axially aligned and configured to generate a magnetic field transverse to the core, and the core also includes an electrically insulating material disposed between the fibers. The device may include any of the following features or combinations thereof:

[0058] Among them, multiple fibers are configured to form a magnetic field perpendicular to the core;

[0059] Each of the fibers has an aspect ratio of at least 3 and a diameter of 100 nm to 10 µm;

[0060] The core includes a first surface and a second surface opposite to the first surface; and each fiber in the fibers extends from the first surface to the second surface.

[0061] The fibers include cross-sectional shapes that are circular, rectangular, triangular, hexagonal, or combinations thereof;

[0062] The core is ring-shaped, and the conductive structure includes conductive wires wound around the core.

[0063] It also includes a second conductive wire wound around the core; and / or

[0064] The core is positioned around the conductive structure such that at least a portion of the conductive structure passes through the core.

[0065] The device may be an inductor, a transformer, or a component that can form a transformer, and / or may be integrated into electrical equipment.

[0066] This document describes a core. The core includes: a plurality of fibers, each fiber comprising a ferromagnetic material; and an electrically insulating material disposed between the fibers, wherein the fibers are axially aligned. The core may include any or a combination of the following features:

[0067] The plurality of fibers are configured to form a magnetic field transverse to the core;

[0068] Each fiber has an aspect ratio of at least 3 and a diameter of 100 nm to 10 µm.

[0069] The fibers include cross-sectional shapes that are circular, rectangular, triangular, hexagonal, or combinations thereof;

[0070] The fiber includes a first fiber having a first cross-sectional shape and a second fiber having a second cross-sectional shape different from the first cross-sectional shape;

[0071] The fiber includes a first fiber having a first diameter and a second fiber having a second diameter smaller than the first diameter; and the first fiber and the second fiber are dispersed within the core.

[0072] The fibers include first fibers formed of a first material and second fibers formed of a second material different from the first material; and the first and second fibers are dispersed within the core; and / or

[0073] The fibers have a uniform diameter, a uniform cross-sectional shape, and / or a uniform composition.

[0074] The core can be integrated into electrical components such as inductors or transformers, and / or can be integrated into electrical devices.

[0075] This document describes a method for manufacturing a core. The method includes: providing an insulated wire comprising an electrically insulating material wound around a metal structure, wherein the metal structure comprises a metal and / or metal oxide in the form of metal wire or compacted metal powder; drawing the insulated wire to form insulating fibers comprising continuous fibers with a diameter of 100 nm to 10 µm and an electrically insulating material coating disposed around the fibers; and combining a plurality of insulating fibers such that the insulating fibers are axially aligned. The method may include any of the following features or a combination thereof:

[0076] The assembly step includes simultaneously pulling out multiple insulated wires;

[0077] Simultaneous drawing is performed at a temperature of at least 200 °C;

[0078] It also includes cutting multiple insulating fibers along the transverse and axial directions;

[0079] In this process, multiple insulating fibers are cut along the axial direction to form a ring;

[0080] It also includes extruding multiple insulating fibers to form a ring; and / or

[0081] The pulling step includes: simultaneously pulling multiple insulated wires to form a bundle comprising multiple insulating fibers; and the combining step includes compacting the multiple bundles together.

[0082] While various embodiments have been shown and described, this disclosure is not limited to such embodiments and should be understood to include all modifications and variations that will be apparent to those skilled in the art. Therefore, it should be understood that this disclosure is not intended to be limited to the specific forms disclosed; rather, the invention is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure as defined by the appended claims.

Claims

1. An apparatus comprising: core; as well as The conductive structure adjacent to the core; The core includes: Multiple fibers, the multiple fibers being axially aligned and configured to form a magnetic field transverse to the core; and Electrically insulating material disposed between the fibers.

2. The apparatus according to claim 1, wherein, The plurality of fibers are configured to be perpendicular to the magnetic field within the core.

3. The apparatus according to claim 1, wherein, Each fiber has an aspect ratio of at least 3 and a diameter of 100 nm to 10 µm.

4. The apparatus according to claim 3, wherein, The core includes a first surface and a second surface opposite to the first surface; and Each fiber in the fiber extends from the first surface to the second surface.

5. The apparatus according to claim 3, wherein, The fibers include cross-sectional shapes that are circular, rectangular, triangular, hexagonal, or combinations thereof.

6. The apparatus according to claim 1, wherein, The core is annular, and the conductive structure includes conductive wires wound around the core.

7. The apparatus of claim 6 further comprises a second conductive wire wound around the core.

8. The apparatus according to claim 1, wherein, The core is positioned around the conductive structure such that at least a portion of the conductive structure passes through the core.

9. A transformer comprising the apparatus according to claim 7, wherein, The conductive wire is the primary winding of the transformer, and the second conductive wire is the secondary winding of the transformer.

10. A core for an inductor, comprising: Multiple fibers, each of which comprises a ferromagnetic material; as well as An electrically insulating material disposed between the fibers in the plurality of fibers; The fibers are arranged axially.

11. The chip according to claim 10, wherein, The plurality of fibers are configured to form a magnetic field transverse to the core.

12. The core according to claim 11, wherein, Each fiber has an aspect ratio of at least 3 and a diameter of 100 nm to 10 µm.

13. The chip according to claim 12, wherein, The fibers include cross-sectional shapes that are circular, rectangular, triangular, hexagonal, or combinations thereof.

14. The chip according to claim 13, wherein, The fiber includes a first fiber having a first cross-sectional shape and a second fiber having a second cross-sectional shape different from the first cross-sectional shape.

15. The chip according to claim 13, wherein, The fiber includes a first fiber having a first diameter and a second fiber having a second diameter smaller than the first diameter; and The first fiber and the second fiber are distributed within the core.

16. The chip according to claim 13, wherein, The fiber includes a first fiber formed of a first material and a second fiber formed of a second material different from the first material; and The first fiber and the second fiber are distributed within the core.

17. The chip according to claim 13, wherein, The fibers have a uniform diameter, a uniform cross-sectional shape, and / or a uniform composition.

18. A transformer comprising the core according to claim 10.

19. A method of manufacturing a core for an inductor, comprising: An insulated wire is provided, the insulated wire comprising an electrically insulating material wound around a metal structure, wherein the metal structure comprises a metal and / or metal oxide in the form of a metal wire or compacted metal powder; The insulating wire is pulled to form insulating fibers, the insulating fibers comprising continuous fibers with a diameter of 100 nm to 10 µm and an electrically insulating material coating disposed around the fibers; and Multiple insulating fibers are combined such that the insulating fibers are axially aligned.

20. The method according to claim 19, wherein, The combination step includes simultaneously pulling out multiple of the insulating wires.

21. The method according to claim 20, wherein, The simultaneous drawing is performed at a temperature of at least 200 °C.

22. The method of claim 20 further comprises cutting a plurality of the insulating fibers in the transverse and axial directions.

23. The method according to claim 22, wherein, The insulating fibers are cut along the axial direction to form a ring.

24. The method of claim 20, further comprising extruding the plurality of said insulating fibers to form a ring.

25. The method according to claim 19, wherein, The pulling step includes simultaneously pulling multiple insulating wires to form a bundle comprising multiple insulating fibers; and The assembly step includes compacting multiple bundles together.

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