Electromagnet coils formed from flexible circuits

Abstract

To form an electromagnet using multiple flexible PCBs.SOLUTION: A method of fabricating an electromagnet includes obtaining a first flexible PCB that includes one or more first conductive coiled traces, and obtaining a second flexible PCB that includes one or more second conductive coiled traces. The first flexible PCB is bent into a shape having at least one curve or corner. With the first flexible PCB having been bent into the shape, the second flexible PCB is then bent into the shape, and the second flexible PCB is positioned adjacent to the first flexible PCB to conform with the first flexible PCB.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to magnetic coils, and more particularly to electromagnetic coils fabricated using flexible printed circuit boards (PCBs). [Background technology]

[0002] Traditionally, electromagnets are formed by hand-winding a specified number of turns of wire into a predetermined shape, thereby forming a magnetic coil. This hand-winding process results in imprecise and non-repeatable wire placement. This imprecision and non-repeatable nature complicates calibration of systems in which the magnetic coil is used. Hand-winding also limits the ability to shape the coil to a specified geometry. For example, the winding radius is constrained, making it impossible to achieve sharp corners. Furthermore, the hand-winding process and the process of connecting the resulting magnetic coil to a power source (e.g., a current source) are prone to human error. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent Application Publication No. 2016 / 0013665 Summary of the Invention [Problem to be solved by the invention]

[0004] Electromagnets have also been fabricated using single-layer flexible printed circuit boards (PCBs), i.e., PCBs on which the coil is formed by conductive traces. However, the number of turns of the coil that can be achieved in a single layer is limited, and therefore the strength of the electromagnet is limited. Adding additional layers to the PCB is impractical because it increases the stiffness of the PCB, thereby preventing it from being bent into the desired shape (i.e., specified geometry) for the electromagnet.

[0005] One such application of electromagnets is the Wien filter, which uses crossed electromagnetic fields to perform velocity filtering on charged particles (e.g., electrons). Wien filters are used in electron microscopes. [Means for solving the problem]

[0006] The above problems are solved by forming an electromagnet using multiple flexible PCBs.

[0007] In certain embodiments, a method includes obtaining a first flexible PCB having one or more first conductive coiled traces and a second flexible PCB having one or more second conductive coiled traces, bending the first flexible PCB into a shape having at least one curve or corner, and then, while the first flexible PCB is bent into the shape, bending a second flexible PCB into the shape, positioning the second flexible PCB adjacent to the first flexible PCB and nesting the second flexible PCB against the first flexible PCB.

[0008] In certain embodiments, an electromagnet includes a first flexible PCB with one or more first conductive coil-like traces. The first flexible PCB is bent into a shape with at least one curve or corner. The electromagnet also includes a second flexible PCB bent into the shape and with one or more second conductive coil-like traces. The second flexible PCB is adjacent to and nestled against the first flexible PCB.

[0009] For a better understanding of various described implementations, reference is made to the following drawings in conjunction with the detailed description below. [Brief explanation of the drawings]

[0010] [Figure 1] 1A-1C illustrate an electromagnet having multiple flexible printed circuit boards (PCBs) bent into a specified shape according to certain embodiments. [Figure 2]1 illustrates a flexible PCB and associated connectors according to certain embodiments. [Figure 3A] 1 illustrates conductive coiled traces on two flexible PCBs along with electrical connections between the conductive coiled traces according to certain embodiments. [Figure 3B] 3B illustrates a cross section of a portion of the flexible PCB of FIG. 3A according to certain embodiments. [Figure 4] 1 illustrates a system having a pair of flexible PCBs bent concentrically to a specified shape and also having a connection ring for a static deflector, according to certain embodiments. [Figure 5] 1A and 1B illustrate cross-sectional and partial perspective views of an assembly in which an electromagnet and an electrostatic deflector are concentrically arranged in accordance with certain embodiments. [Figure 6A] 1 is a flowchart illustrating a method for manufacturing an electromagnet using multiple flexible PCBs in accordance with certain embodiments. [Figure 6B] 6B is a flowchart illustrating an optional continuation portion of the method of FIG. 6A, according to certain embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0011] Like reference characters refer to corresponding parts throughout the specification and drawings.

[0012] Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth to provide a consistent understanding of the various described embodiments. However, those skilled in the art will appreciate that the various described embodiments may practice without such specific details. In other instances, well-known methods, procedures, components, circuits, and networks have not been described in detail so as not to unnecessarily obscure aspects of the embodiments.

[0013] 1 illustrates an electromagnet 100 having multiple flexible printed circuit boards (PCBs) 102 bent into a specified shape according to certain embodiments. The flexible PCBs 102 include a first flexible PCB 102-1 and a second flexible PCB 102-2. Each PCB 102 has one or more conductive coiled traces 104, e.g., the first flexible PCB 102-1 has one or more conductive coiled traces 104-1, and the second flexible PCB 102-2 has one or more conductive coiled traces 104-2. The second flexible PCB 102-2 is adjacent to and generally surrounds the first flexible PCB 102-1, except for a small gap 106 that results from the first and second flexible PCBs 102-1 and 102-2 being the same size in some embodiments. In certain embodiments, one or more additional flexible PCBs 102, each having one or more individual conductive coil traces 104, are disposed between the first and second flexible PCBs 102-1, 102-2. Adjacent flexible PCBs 102 may be mechanically coupled (e.g., adhesively coupled).

[0014] 1, the specified shape, i.e., the shape into which the flexible PCB 102 is bent, is a truncated cone, with the first flexible PCB 102-1 and the second flexible PCB 102-2 arranged concentrically about a radial axis. Other shapes are also possible. For example, the flexible PCB 102 may be bent into a shape having a cylindrical, elliptical, rectangular, or polygonal cross section.

[0015] When a current is applied to the conductive coiled traces 104, a magnetic field is generated within the space enclosed by the flexible PCBs 102. To supply the current to the conductive coiled traces 104, the electromagnet 100 is provided with connectors 108-1 and 108-2. Connector 108-1 is mechanically coupled to the first flexible PCB 102-1 and includes one or more conductors (e.g., conductive traces) electrically connected to the one or more conductive coiled traces 104-1. Connector 108-2 is mechanically coupled to the second flexible PCB 102-2 and includes one or more conductors (e.g., conductive traces) electrically connected to the one or more conductive coiled traces 104-2. In some embodiments, connector 108-1 is a flexible PCB integrally formed with flexible PCB 102-1, and connector 108-2 is a flexible PCB integrally formed with flexible PCB 102-2. Connectors 108-1 and 108-2 are connected to a power source, e.g., a current source (not shown). In certain embodiments, one or more conductive coiled traces 104 on adjacent flexible PCBs 102 are electrically connected via contacts on the surfaces of the flexible PCBs 102. For example, when flexible PCBs 102-1 and 102-2 are adjacent, one or more conductive coiled traces 104-1 can be electrically connected to one or more conductive coiled traces 104-2 via one or more contacts (e.g., contacts 202 in FIG. 2) on the flexible PCBs 102-1 and 102-2.

[0016] FIG. 2 illustrates a flexible PCB 200 and associated connector 206 according to certain embodiments. The flexible PCB 200 shown in FIG. 2 has not yet been bent into a specified shape. The flexible PCB 200 may be an example of a flexible PCB 102 (FIG. 1), which may include a first flexible PCB 200-1, a second flexible PCB 200-2, a third flexible PCB 200-3, and a fourth flexible PCB 200-4. Each flexible PCB 200 includes one or more conductive coiled traces (not shown) (e.g., conductive coiled traces 302-1, 302-2, 304-1, and 304-2 in FIG. 3A). The first flexible PCB 200-1 includes contacts 202 that can be electrically connected to similar contacts (not visible) on the second flexible PCB 200-2, thereby electrically connecting the conductive coiled traces on the first and second PCBs 200-1 and 200-2. Similarly, the third flexible PCB 200-3 has contacts 202 that can be electrically connected to similar contacts (not visible) on the fourth flexible PCB 200-4 to electrically connect the conductive coiled traces on the third and fourth PCBs 200-3 and 200-4.

[0017] Connector 206 has a first arm 204-1 mechanically and electrically coupled to first flexible PCB 200-1 and a second arm 204-2 mechanically and electrically coupled to third flexible PCB 200-3. First arm 204-1 may be an example of connector 108-1, and second arm 204-2 may be an example of connector 108-2 (or vice versa). In certain embodiments, connector 206, including first arm 204-1 and / or second arm 204-2, is integrally formed with first flexible PCB 200-1 and / or third flexible PCB 200-3. Connector 206 is mechanically and electrically coupled to contact pads 208 and includes conductors (not shown) that electrically couple conductive coiled traces on flexible PCBs 200-1 through 200-4 with contacts 210 on contact pads 208 (e.g., conductors 312 and 314 in FIG. 3A and traces 406-1 and 406-2 in FIG. 4). These conductors within connector 206 may be conductive traces. Contacts 210 may be electrically coupled to a power source (e.g., a current source), thereby electrically coupling the conductive coiled traces on flexible PCBs 200-1 through 200-4 to the power source.

[0018] According to certain embodiments, the four flexible PCBs 200-1 through 200-4 can be bent into the same shape and placed concentrically across from one another (i.e., next to one another) to form a single electromagnet (e.g., electromagnet 100 in FIG. 1). In this example, the conductive coil traces on the four flexible PCBs 200-1 through 200-4 can be connected in series, so that the current polarity is the same for the conductive coil traces on all four flexible PCBs 200-1 through 200-4. The additional conductive coil traces provided by the third and fourth flexible PCBs 200-3 and 200-4 result in a stronger electromagnet than if only two flexible PCBs 200-1 and 200-2 were used.

[0019] According to certain other embodiments, first and second flexible PCBs 200-1 and 200-2 can be bent into the same shape and placed concentrically opposite each other (i.e., next to each other) to form a first electromagnet (e.g., first electromagnet 100 in FIG. 1). Third and fourth flexible PCBs 200-3 and 200-4 can be bent into the same shape and placed concentrically opposite each other (i.e., next to each other) to form a second electromagnet (e.g., second electromagnet 100 in FIG. 2) that is separate from the first electromagnet.

[0020] In certain embodiments, the conductive coiled traces in the first and second flexible PCBs 200-1 and 200-2 are electrically connected in series, such that the current polarity is the same for the conductive coiled traces on the first and second PCBs 200-1 and 200-2. That is, the first and second flexible PCBs 200-1 and 200-2 form an electromagnet. On the other hand, one or more conductive coiled traces in the third flexible PCB 200-3 are not connected in series with one or more conductive coiled traces in the fourth flexible PCB 200-4. Instead, one or more conductive coiled traces in the third flexible PCB 200-3 are wired to carry current with a polarity opposite to the polarity of the current passing through one or more conductive coiled traces in the fourth flexible PCB 200-4. This configuration can be achieved by electrically coupling the conductive coiled traces of the third and fourth PCBs 200-3 and 200-4 to respective contacts 210 on the contact pads 208 that provide current of the desired polarity. In this configuration, the magnetic field generated by one or more conductive coiled traces in the fourth flexible PCB 200-4 will be opposite to, and therefore cancel, the magnetic field generated by one or more conductive coiled traces in the third flexible PCB 200-3. This combination of third and fourth PCBs 200-3 and 200-4 positioned concentrically across from one another (i.e., next to one another) will provide a heater that can be used to cancel thermal fluctuations associated with the combination of the first and second PCBs 200-1 and 200-2 (positioned concentrically across from one another). When the current supplied to the first and second PCBs 200-1 and 200-2 is decreased (or increased), the current supplied to the third and fourth PCBs 200-3 and 200-4 can be increased (or decreased) by a corresponding amount to counteract the change in heat generation and provide overall steady heating, which desirably maintains calibration and ensures consistent performance of the system.

[0021] 3A illustrates conductive coil traces on two flexible PCBs 300-1 and 300-2 and the electrical connections between them, according to certain embodiments. Flexible PCBs 300-1 and 300-2 may be examples of flexible PCBs 200-1 and 200-2 (FIG. 2), flexible PCBs 200-3 and 200-4 (FIG. 2), and / or flexible PCBs 102-1 and 102-2 (FIG. 1). Flexible PCBs 300-1 and 300-2 each have a pair of conductive coil traces 302-1 and 302-2 on a first side 308 and a pair of conductive coil traces 304-1 and 304-2 on a second side 310. First side 308 is separated from second side 310 by an insulating (e.g., polyimide) layer (e.g., insulating layer 322 in FIG. 3B). Conductive coiled traces 302-1 and 302-2 on first side 308 are covered by a first insulating (e.g., polyimide) cover layer (e.g., cover layer 320 in FIG. 3B). Similarly, conductive coiled traces 304-1 and 304-2 on second side 310 are covered by a second insulating (e.g., polyimide) cover layer (e.g., cover layer 324 in FIG. 3B).

[0022] Conductive coiled traces 302 and 304 are rectangular spirals, each having a specified number of turns. A rectangular spiral has adjacent sides that are perpendicular to one another and meet at approximately right angles (although some corner curvature may be present in some embodiments). While FIG. 3A shows four turns, the number of turns can generally vary. For example, five, six, or more turns are also possible. Furthermore, each of flexible PCBs 300-1 and 300-2 may have only one conductive coiled trace 302 on the first side 308 and only one conductive coiled trace 304 on the second side 310, or may have more than two conductive coiled traces 302 on the first side 308 and more than two conductive coiled traces 304 on the second side 310. In certain embodiments, conductive coiled traces 302 and 304 are copper.

[0023] Conductive coiled trace 302-1 is electrically connected to conductive coiled trace 302-2, both of which are formed by a single elongated trace as shown. The inner end of conductive coiled trace 302-1 is electrically connected to the inner end of conductive coiled trace 304-1 through via 306-1. Similarly, the inner end of conductive coiled trace 302-2 is electrically connected to the inner end of conductive coiled trace 304-2 through via 306-2. In certain embodiments, vias 306-1 and 306-2 are copper. The outer end of conductive coiled trace 304-1 on flexible PCB 300-1 is electrically connected to the outer end of conductive coiled trace 304-2 on flexible PCB 300-2 through contact 307 (e.g., contact 202 in FIG. 2). The outer end of conductive coiled trace 304-1 on flexible PCB 300-2 is electrically connected to conductor 312 (e.g., a conductive trace within connector 206 in FIG. 2 and / or connector 108 in FIG. 1, conductive trace 406 in FIG. 4). The outer end of conductive coiled trace 304-2 on flexible PCB 300-1 is electrically connected to conductor 314 (e.g., a conductive trace within connector 206 in FIG. 2 and / or connector 108 in FIG. 1). These conductors 312 and 314 provide current to conductive coiled traces 302 and 304, which are connected in series between conductors 312 and 314. FIG. 3A shows one example of a series connection of conductive coiled traces 302 and 304, and other series connections are possible.

[0024] FIG. 3B illustrates a cross section of a portion of a flexible PCB 300 (e.g., flexible PCB 300-1 or 300-2 in FIG. 3A) according to certain embodiments. A conductive coiled trace 302 (e.g., conductive coiled trace 302-1 or 302-2 in FIG. 3A) is disposed on a first side of the PCB 300. A conductive coiled trace 304 (e.g., conductive coiled trace 304-1 or 304-2 in FIG. 3A) is disposed on a second side of the PCB 300. An insulating (e.g., polyimide) layer 322 is located in the middle half of the flexible PCB 300 and separates the conductive coiled trace 302 from the conductive coiled trace 304. A via 306 electrically connects the conductive coiled trace 302 to the conductive coiled trace 304. In certain embodiments, the conductive coiled traces 302 and 304 and the via 306 are copper. An insulating (e.g., polyimide) cover layer 320 covers conductive coiled trace 302 on a first side, and an insulating (e.g., polyimide) cover layer 324 covers conductive coiled trace 304 on a second side. Flexible PCB 300 has one or more contacts (not visible) for electrically connecting conductive coiled traces 302 and 304 with conductive coiled traces on another flexible PCB (e.g., that leading to another realization of flexible PCB 300) (e.g., contact 202 in FIG. 2). Flexible PCB 300 also has one or more contacts (not visible) for electrically connecting conductive coiled traces 302 and 304 with conductors within a connector (e.g., connector 206 in FIG. 2, connector 108 in FIG. 1, connector 404 in FIG. 4).

[0025] 4 illustrates a system in which a pair of flexible PCBs 400-1 and 400-2 are bent concentrically into a specified shape, such that flexible PCB 400-1 is generally surrounded by flexible PCB 400-2, according to certain embodiments. Flexible PCBs 400-1 and 400-2 each include one or more conductive coil traces (not shown). For example, flexible PCBs 400-1 and 400-2 may be implementations of flexible PCBs 102-1 and 102-2 (FIG. 1), 202-1 and 202-2 (FIG. 2), 202-3 and 202-4 (FIG. 2), and / or 300-1 and 300-2 (FIG. 3A). One or more conductive coiled traces of flexible PCBs 400-1 and 400-2 are electrically connected to contact pads 408 (e.g., contact pads 208 in FIG. 2) through first arm 402-1 of connector 404. Conductive traces, including trace 406-1 (e.g., plus another trace on the non-visible side of first arm 402-1), may complete a circuit between contact pads 408 and the conductive coiled traces of flexible PCBs 400-1 and 400-2. The connector has a second arm 402-2 (e.g., arm 204-2 in FIG. 2) having one or more conductive traces, some of which can be electrically connected by trace 406-2 (e.g., plus another trace on the non-visible side of second arm 402-2) to conductive coiled traces on a second pair of flexible PCBs (not shown), such as those described in connection with FIG. 2, or alternatively to one or more conductive coiled traces on flexible PCB 400-2.

[0026] The system of Figure 4 also includes a connection ring 412 for an electrostatic deflector (e.g., that shown in Figure 5) according to certain embodiments. The connection ring 412 includes contacts 414 that provide electrical connection to the individual poles of the electrostatic connector (e.g., poles 504 in Figure 5). The connection ring 412 is electrically connected to contact pads 408 through the connector 410 (e.g., through conductive traces within the connector 410). The contact pads 408 can be coupled to a power source (e.g., a voltage source) for biasing the poles of the electrostatic deflector.

[0027] FIG. 5 shows a cross-sectional and partial perspective view of an assembly 500 in which an electromagnet 502 and an electrostatic deflector are concentrically arranged according to certain embodiments. The assembly 500 can be a Wien filter (e.g., for an electron microscope). The electromagnet 502 includes multiple flexible PCBs with conductive coil traces (e.g., flexible PCBs 102-1 and 102-2 in FIG. 1 ; 200-1, 200-2, 200-3, and / or 200-4 in FIG. 2 ; 300-1 and 300-2 in FIG. 3A ; 400-1 and 400-2 in FIG. 4 ). The multiple flexible PCBs are arranged concentrically adjacent to each other. The electrostatic deflector includes multiple poles 504, each with a conductive surface (e.g., eight poles 504 for an eight-pole electrostatic deflector). The poles 504 are radially arranged within an aperture surrounded by electromagnet 502. When the poles 504 are biased, an electric field is generated within the aperture surrounded by electromagnet 502. When the poles 504 are biased simultaneously with current being applied to the flexible PCBs, simultaneous electric and magnetic fields are generated within the aperture. The simultaneous electric and magnetic fields can be orthogonal. Connecting ring 506 (e.g., connecting ring 412 in FIG. 4) carries conductive contacts (not visible) for poles 504 (e.g., contacts 414 in FIG. 4). Screws 508 or other suitable connecting mechanism hold connecting ring 506 in place and connect the individual conductive contacts to poles 504.

[0028] 6A is a flowchart illustrating 600 fabricating an electromagnet (e.g., electromagnet 100 in FIG. 1 or electromagnet 502 in FIG. 5) (or, in some embodiments, a zero-field device) using multiple flexible PCBs according to certain embodiments. In method 600, a first flexible PCB (e.g., flexible PCB 102-1 in FIG. 1, 200-1 or 200-3 in FIG. 2, 300-1 in FIG. 3A, 400-1 in FIG. 4) having one or more first conductive coiled traces (e.g., conductive coiled trace 104-1 in FIG. 1, conductive coiled traces 302-1, 302-2, 304-1, and 304-2 in FIG. 3A) is obtained. In certain embodiments, the one or more first conductive coiled traces are formed into a rectangular spiral trace (604). A second flexible PCB (e.g., flexible PCB 102-2 in FIG. 1, 200-2 or 200-4 in FIG. 2, 300-2 in FIG. 3A, 400-2 in FIG. 4) having one or more second conductive coiled traces (e.g., conductive coiled trace 104-2 in FIG. 1, conductive coiled traces 302-1, 302-2, 304-1, and 304-2 in FIG. 3A) is also obtained (606). In certain embodiments, the one or more second conductive coiled traces are rectangular spiral traces (608).

[0029] The first flexible PCB is bent 610 into a shape having at least one curve or corner. In some embodiments, the shape is a frustum of a cone 612. Other examples of the shape include, but are not limited to, a cylindrical, elliptical, rectangular, or polygonal cross section. In some embodiments, the first flexible PCB is bent 614 by wrapping it around a fixture having the shape. The fixture is later removed (e.g., after all of the flexible PCBs have been bent into the shape).

[0030] Then, with the first flexible PCB bent to that shape, a second flexible PCB is bent (616) to that shape, and the second flexible PCB is positioned adjacent to (e.g., concentrically with) the first flexible PCB. In some embodiments, the second flexible PCB is mechanically coupled (618) to the first flexible PCB while bent to that shape. For example, the second flexible PCB is attached to the first flexible PCB using adhesive (620).

[0031] In certain embodiments, one or more first conductive coiled traces are electrically connected in series with one or more second conductive coiled traces (e.g., via contacts 202 in FIG. 2 or via contacts 307 in FIG. 3A) (622). The first and second flexible PCBs are aligned according to method 600, thereby forming an electromagnet.

[0032] In certain other embodiments, the one or more second conductive coiled traces are configured to carry current with an opposite polarity to the one or more first conductive coiled traces (i.e., the one or more first conductive coiled traces carry current with a first polarity and the one or more second conductive coiled traces carry current with a second polarity opposite the first polarity) (624). Thus, the magnetic field generated by the first flexible PCB cancels the magnetic field generated by the second flexible PCB, resulting in a zero-field device that functions as a heater.

[0033] 6B is a flowchart illustrating an optional continuation portion of method 600 according to certain embodiments. In this continuation portion of method 600, a third flexible PCB (e.g., flexible PCB 200-3 in FIG. 2, an implementation of PCB 300-1 in FIG. 3A) having one or more third conductive coiled traces (e.g., conductive coiled traces 302-1, 302-2, 304-1, and 304-2 in FIG. 3A) is obtained (632). In certain embodiments, the one or more third conductive coiled traces are rectangular spiral traces (634). A fourth flexible PCB (e.g., flexible PCB 200-4 in FIG. 2, an implementation of PCB 300-2 in FIG. 3A) having one or more fourth conductive coiled traces (e.g., conductive coiled traces 302-1, 302-2, 304-1, and 304-2 in FIG. 3A) is also obtained (636). In some embodiments, the one or more fourth conductive coiled traces are rectangular spiral traces (638).

[0034] Then, with the first and second flexible PCBs bent to that shape, a third flexible PCB is bent (640) to that shape, positioned adjacent to and nested (e.g., concentrically) with the second flexible PCB. In some embodiments, the third flexible PCB is mechanically coupled (642) to the second flexible PCB while bent to that shape. For example, the third flexible PCB is attached to the second flexible PCB using adhesive (644).

[0035] Then, with the first, second, and third flexible PCBs bent to that shape, the fourth flexible PCB is bent (646) to that shape, positioned adjacent to and nested (e.g., concentrically) with the third flexible PCB. In some embodiments, while bent to that shape, the fourth flexible PCB is mechanically coupled (648) to the third flexible PCB. For example, the fourth flexible PCB is attached to the third flexible PCB using adhesive (650).

[0036] In certain embodiments, one or more third conductive coiled traces are electrically connected (652) to one or more fourth conductive coiled traces (e.g., via contacts 202 in FIG. 2 or via contacts 307 in FIG. 3A). For example, one or more third and fourth conductive coiled traces are configured (654) to carry current with the same polarity as one or more first and second conductive coiled traces (e.g., one or more first, second, third, and fourth conductive coils are connected in series). The four flexible PCBs are arranged according to method 600 to form an electromagnet. In another example, one or more third and fourth conductive coiled traces are configured to carry current with an opposite polarity to the one or more first and second conductive coiled traces (i.e., the one or more first and second conductive coiled traces carry current with a first polarity and the one or more third and fourth conductive coiled traces carry current with a second polarity opposite the first polarity) 656. Thus, the magnetic fields generated by the first and second flexible PCBs cancel the magnetic fields generated by the third and fourth flexible PCBs, resulting in a zero magnetic field device that functions as a heater.

[0037] In yet certain other embodiments, one or more first and second conductive coiled traces are configured 658 to carry current with the same polarity (e.g., connected in series), thus forming an electromagnet with the first and second flexible PCBs arranged according to method 600. Meanwhile, one or more third conductive coiled traces are configured 658 to carry current with an opposite polarity to one or more fourth conductive coiled traces (i.e., one or more third conductive coiled traces carry current with a first polarity and one or more fourth conductive coiled traces carry current with a second polarity opposite the first polarity). With the third and fourth flexible PCBs arranged according to method 600, a zero-field device is thereby formed that functions as a heater. This heater can counteract changes in heating caused by the electromagnet formed by the first and second flexible PCBs.

[0038] Method 600 may include more or fewer operations. The order of non-order-dependent operations may be changed and / or operations may be combined into a single operation. For example, steps 632 and 636 may be performed simultaneously with steps 602 and 606 prior to the performance of any other steps. Also, for example, the steps of bending, mechanically coupling, and / or electrically connecting an individual flexible PCB to another PCB may be combined into a single step.

[0039] The method 600, and the flexible PCBs arranged as disclosed herein, allows for multiple layers of conductive coils to be stacked into an electromagnet to achieve a strong magnetic field, while still allowing the electromagnet to be shaped as desired. The magnetic coils (i.e., conductive coiled traces) can have sharp corners or tight winding radii. Such electromagnets can be manufactured reproducibly with minimal error.

[0040] The foregoing description is for purposes of explanation and has been described with reference to specific embodiments. However, the illustrative discussion above is not intended to be rigorous or to limit the scope of the claims to the precise forms disclosed. Many modifications and variations are possible in light of the above teachings. The embodiments have been chosen to best explain the principles underlying the claims and their practical application, and to enable others skilled in the art to best utilize various modifications of the embodiments as appropriate for the specific use envisioned.

Claims

1. a first flexible printed circuit board (PCB) having one or more first conductive coiled traces, the first flexible PCB being bent into a shape having at least one bend or corner; an electromagnet comprising a second flexible PCB bent into said shape and having one or more second conductive coiled traces, said second flexible PCB being adjacent to and adjacent to said first flexible PCB and surrounding said first flexible PCB;

2. 2. The electromagnet of claim 1, wherein the one or more first conductive coiled traces are electrically connected to the one or more second conductive coiled traces.

3. 2. The electromagnet of claim 1, wherein the shape is a truncated cone.

4. 2. The electromagnet of claim 1, wherein the one or more first conductive coiled traces and the one or more second conductive coiled traces are rectangular spiral traces.

5. 2. The electromagnet of claim 1, wherein the first and second PCBs are mechanically coupled by an adhesive.

6. 2. The electromagnet according to claim 1, the one or more first conductive coiled traces include a first conductive coiled trace on a first side of the first flexible PCB and a second conductive coiled trace on a second side of the first flexible PCB, the first flexible PCB comprising an insulating layer separating the first side from the second side; the first flexible PCB further comprising a via extending through the insulating layer and electrically connecting the first conductive coiled trace with the second conductive coiled trace; the one or more second conductive coiled traces include a third conductive coiled trace on a first side of the second flexible PCB and a fourth conductive coiled trace on a second side of the second flexible PCB, the second flexible PCB comprising an insulating layer separating the first side from the second side; The electromagnet, wherein the second flexible PCB further comprises a via extending through the insulating layer and electrically connecting the third conductive coiled trace with the fourth conductive coiled trace.

7. 2. The electromagnet according to claim 1, further comprising: a third flexible PCB bent into said shape and including one or more third conductive coiled traces, said third flexible PCB being adjacent to and nestled against said second flexible PCB; an electromagnet comprising a fourth flexible PCB bent into said shape and comprising one or more fourth conductive coiled traces, said fourth flexible PCB being adjacent to and nestled against said third flexible PCB;

8. 8. The electromagnet of claim 7, wherein the one or more third conductive coiled traces and the one or more fourth conductive coiled traces are configured to carry current with the same polarity as the one or more first conductive coiled traces and the one or more second conductive coiled traces.

9. 8. The electromagnet according to claim 7, the one or more first conductive coiled traces and the one or more second conductive coiled traces are configured to carry electrical current with a first polarity; an electromagnet, wherein the one or more third conductive coiled traces and the one or more fourth conductive coiled traces are configured to carry a current with a second polarity opposite the first polarity.

10. 2. The electromagnet according to claim 1, the one or more first conductive coiled traces are configured to carry a current of a first polarity; an electromagnet, wherein the one or more second conductive coiled traces are configured to carry a current with a second polarity opposite the first polarity;

11. 1. An assembly comprising: It is an electromagnet, a first flexible printed circuit board (PCB) having one or more first conductive coiled traces, the first flexible PCB being bent into a shape having at least one bend or corner; an electromagnet comprising a second flexible PCB bent into said shape and comprising one or more second conductive coiled traces, said second flexible PCB being adjacent to and adjacent to said first flexible PCB and surrounding said first flexible PCB; and an electrostatic deflector concentrically disposed with respect to said first and second flexible PCBs; An assembly comprising:

12. obtaining a first flexible printed circuit board (PCB) having one or more first conductive coiled traces; obtaining a second flexible PCB having one or more second conductive coiled traces; bending the first flexible PCB into a shape having at least one curve or corner; With the first flexible PCB bent into the shape, the second flexible PCB is bent into the shape, and at the same time, the second flexible PCB is positioned next to the first flexible PCB, leaning against the first flexible PCB and surrounding the first flexible PCB.

13. 13. The method of claim 12, further comprising electrically connecting the one or more first conductive coiled traces with the one or more second conductive coiled traces.

14. 13. The method of claim 12, wherein the shape is a frustum of a cone.

15. 13. The method of claim 12, wherein the one or more first conductive coiled traces and the one or more second conductive coiled traces are rectangular spiral traces.

16. 13. The method of claim 12, The method further comprises: winding the first flexible PCB around a fixture during the bending; After wrapping the first flexible PCB around the fixture, the fixture is removed.

17. 13. The method of claim 12, further comprising mechanically coupling the second flexible PCB to the first flexible PCB with an adhesive while bent into the shape.

18. 13. The method of claim 12, the one or more first conductive coiled traces include a first conductive coiled trace on a first side of the first flexible PCB and a second conductive coiled trace on a second side of the first flexible PCB, the first flexible PCB comprising an insulating layer separating the first side from the second side; the first flexible PCB further comprising a via extending through the insulating layer and electrically connecting the first conductive coiled trace with the second conductive coiled trace; the one or more second conductive coiled traces include a third conductive coiled trace on a first side of the second flexible PCB and a fourth conductive coiled trace on a second side of the second flexible PCB, the second flexible PCB comprising an insulating layer separating the first side from the second side; The method wherein the second flexible PCB further comprises a via extending through the insulating layer and electrically connecting the third conductive coiled trace with the fourth conductive coiled trace.

19. 13. The method of claim 12, further comprising: obtaining a third flexible PCB having one or more third conductive coiled traces; obtaining a fourth flexible PCB having one or more fourth conductive coiled traces; With the first and second flexible PCBs bent into the shape, bend the third flexible PCB into the shape, while positioning the third flexible PCB next to the second flexible PCB and nestling it against the second flexible PCB; With the first, second and third flexible PCBs bent into the shape, the fourth flexible PCB is bent into the shape, and at the same time, the fourth flexible PCB is positioned adjacent to the third flexible PCB and nestled against the third flexible PCB.

20. 20. The method of claim 19, further comprising: electrically connecting the one or more first conductive coiled traces with the one or more second conductive coiled traces; electrically connecting the one or more third conductive coiled traces with the one or more fourth conductive coiled traces.

21. 20. The method of claim 19, further configuring the one or more third conductive coiled traces and the one or more fourth conductive coiled traces to carry current with the same polarity as the one or more first conductive coiled traces and the one or more second conductive coiled traces.

22. 20. The method of claim 19, further comprising: configuring the one or more first conductive coiled traces and the one or more second conductive coiled traces to carry a current with a first polarity; The method further comprising configuring the one or more third conductive coiled traces and the one or more fourth conductive coiled traces to carry a current with a second polarity opposite to the first polarity.

23. 20. The method of claim 19, further comprising: the one or more first conductive coiled traces and the one or more second conductive coiled traces are configured to carry electrical current with the same polarity; The method further comprises configuring the one or more third conductive coiled traces and the one or more fourth conductive coiled traces to carry current with opposite polarities.

24. 13. The method of claim 12, further comprising: the one or more first conductive coiled traces are configured to carry a current with a first polarity; The one or more second conductive coiled traces are configured to carry a current with a second polarity opposite to the first polarity.

25. 13. The method of claim 12, further comprising: positioning an electrostatic deflector concentrically with respect to the first and second flexible PCBs.

26. obtaining a first flexible printed circuit board (PCB) having one or more first conductive coiled traces; obtaining a second flexible PCB having one or more second conductive coiled traces; bending the first flexible PCB into a shape having at least one curve or corner; With the first flexible PCB bent into the shape, bend the second flexible PCB into the shape, while positioning the second flexible PCB next to the first flexible PCB and nestling it against the first flexible PCB; A method for arranging an electrostatic deflector concentrically with respect to the first and second flexible PCBs.

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