WO2024182433A1 - Induction reflow of printed circuit board assembly - Google Patents

Abstract

Aspects of the present disclosure relate to induction reflow systems and related induction reflow methods. In certain embodiments, the induction reflow system comprises a power supply and a plurality of induction coils. Solder can be inductively reflowed to form solder joints on a printed circuit board using the inductive reflow system. In some applications, the power supply can apply alternating current having a frequency of at least 1 megahertz.

Description

TSLA.770WO PATENT INDUCTION REFLOW OF PRINTED CIRCUIT BOARD ASSEMBLY CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit of U.S. Provisional Patent Application No. 63/487,568, entitled “INDUCTION REFLOW OF PRINTED CIRCUIT BOARD ASSEMBLY,” filed on February 28, 2023, the disclosure of which is hereby incorporated by reference in its entirety and for all purposes. BACKGROUND Technical Field [0002] This disclosure relates generally to an electronic assembly system and methods for assembling electronic components using an induction reflow. Description of Related Technology [0003] In the assembly of electronic components, various electronic components can be assembled on a printed circuit board (PCB). The assembly process can involve the use of solder paste. Solder paste can be precisely applied to the designated pads on the PCB surface, which are arranged according to the specific layout of the PCB. Once the solder paste is in place, the electronic components can be positioned directly onto the corresponding pads coated with this paste. The electronic components are then securely affixed to the PCB through a heating process, whereby the solder paste is melted. This melting causes the solder to flow and create a solid bond between the component and the pad on the PCB. Reflow can be performed in a variety of manufacturing processes for assembling electronic components on a PCB. Improved reflow techniques are generally desirable. SUMMARY [0004] The innovations described in the claims each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of the claims, some prominent features of this disclosure will now be briefly described. [0005] One aspect of the present disclosure is a method of method of assembling one or more electrical components on a printed circuit board (PCB). The method includes providing alternating current power to a plurality of induction coils and concurrently transmitting magnetic fields from the plurality of induction coils to solder material on the PCB to form a plurality of solder joints on the PCB. [0006] In one embodiment, a single power source can provide the alternating current power to the plurality of induction coils. [0007] In one embodiment, a first induction coil of the plurality of induction coils can form at least two of the plurality of solder joints. [0008] In one embodiment, the alternating current power can have a frequency of at least 1 megahertz. [0009] In one embodiment, the frequency of the alternating current power can be in a range from 2 megahertz to 40 megahertz. [0010] In one embodiment, a magnetic field of a first induction coil of the plurality of induction can be transmitted to the solder material through a flux concentrator. [0011] In one embodiment, the induction coil can be a single turn coil. [0012] In one embodiment, a first solder joint of the plurality of solder joints can be electrically connected to a surface mount component positioned on the PCB. [0013] In one embodiment, the solder joint can be electrically connected to a surface mount component positioned on the PCB. [0014] In one embodiment, a first solder joint of the plurality of solder joints can be electrically connected to a through-hole component. [0015] In one embodiment, an electronic component on the PCB can be included in a wireless charging pad configured to supply 400 Volts of direct current power from wirelessly received alternating current power. Additionally, at least one of the solder joints can be connected to the electronic component. [0016] Another aspect of the present disclosure is a method of assembling one or more electrical components on a printed circuit board (PCB) with induction reflow. The method includes providing alternating current power to an induction coil and transmitting a magnetic field from the induction coil to solder material on the PCB to form a plurality of solder joints on the PCB. [0017] In one embodiment, the method can further include, while transmitting the magnetic field from the induction coil, transmitting a second magnetic field from a second induction coil to form at least one additional solder joint on the PCB. [0018] In one embodiment, a single power supply can provide alternating current power to the induction coil and the second induction coil. [0019] In one embodiment, the alternating current can have a frequency of at least 1 megahertz. [0020] Another aspect of the present disclosure is a method of assembling one or more electrical components on a printed circuit board (PCB) with induction reflow. The method includes providing alternating current power to an induction coil and transmitting a magnetic field from the induction coil to solder material on the PCB to form a solder joint on the PCB. The alternating current power has a frequency of greater than 1 megahertz. [0019] In one embodiment, transmitting the magnetic field from the induction coil can form a plurality of solder joints, the plurality of solder joints including the solder joint. [0019] In one embodiment, the frequency can be in a range from 2 megahertz to 10 megahertz. In one embodiment, the frequency is can be in a range from 2 megahertz to 40 megahertz. [0021] Another aspect of the present disclosure is an induction reflow system that includes a power supply and an induction coil connected to the power supply. The power supply is configured to generate alternating current having a frequency of greater than 1 megahertz. The induction coil is sized to surround one or more electronic components positioned on a printed circuit board. Additionally, the induction coil is configured to apply a magnetic field to inductively reflow solder to from at least one solder joint connected to at least one of the one or more electronic components. [0022] In one embodiment, the transmitting the magnetic field from the induction coil forms a plurality of solder joints, the plurality of solder joints including the solder joint. [0023] In one embodiment, the alternating current can have a frequency in a range from 2 megahertz to 10 megahertz. [0024] In one embodiment, the alternating current can have a frequency in a range from 2 megahertz to 40 megahertz. [0025] Another aspect of the present disclosure is an induction reflow system that includes a power supply and a plurality of induction coils. A power supply is configured to generate alternating current. The plurality of induction coils is configured to apply magnetic fields to inductively reflow solder to concurrently from a plurality of solder joints on a printed circuit board. [0026] In one embodiment, the induction reflow system can further include a flux concentrator to focus the magnetic field applied by the induction coil for forming the solder joint. [0027] In one embodiment, the alternating current can have a frequency of at least 1 megahertz. [0028] In one embodiment, the frequency of the alternating current can be in a range from 2 megahertz to 40 megahertz. [0029] In one embodiment, the power supply can include an inverter configured to generating the alternating current from direct current. [0030] In one embodiment, a first induction coil of the plurality of induction coils can have a single turn. [0031] For purposes of summarizing the disclosure, certain aspects, advantages and novel features of the innovations have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, the innovations may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. BRIEF DESCRIPTION OF THE DRAWINGS [0032] These and other features, aspects, and advantages of the disclosure are described with reference to drawings of certain embodiments, which are intended to illustrate, but not to limit, the present disclosure. It is to be understood that the accompanying drawings, which are incorporated in and constitute a part of this specification, are for the purpose of illustrating concepts disclosed herein and may not be to scale. [0033] FIG. 1A is an illustration of an example of an induction reflow system according to some embodiments. [0034] FIG. 1B is an illustration of an example of an induction reflow system having a multitude of induction coils according to some embodiments. [0035] FIGs. 2A-2C illustrate various examples of inverter circuit topologies according to some embodiments. [0036] FIG. 3 illustrates an example of an induction reflow system performing induction reflow on a PCB assembly according to some embodiments. [0037] FIG. 4 illustrates an example of a cross-sectional view of a PCB assembly during induction reflow according to some embodiments. [0038] FIG. 5 illustrates an example of a PCB assembly with solenoid shape induction coil being used for induction reflow according to some embodiments. [0039] FIG. 6A illustrates an example of a PCB assembly according to some embodiments. [0040] FIG. 6B illustrates an example of a PCB assembly where an induction reflow system can form a plurality of joints according to some embodiments. [0041] FIGs. 7A – 7F illustrate various induction coils for inductive reflow according to some embodiments. [0042] FIG.8 illustrates an example of PCB assembly where a solder joint is being formed by induction reflow according to some embodiments. DETAILED DESCRIPTION [0043] The following detailed description of certain embodiments presents various descriptions of specific embodiments. However, the innovations described herein can be embodied in a multitude of different ways, for example, as defined and covered by the claims. In this description, reference is made to the drawings where like reference numerals and/or terms can indicate identical or functionally similar elements. It will be understood that elements illustrated in the figures are not necessarily drawn to scale. Moreover, it will be understood that certain embodiments can include more elements than illustrated in a drawing and/or a subset of the elements illustrated in a drawing. Further, some embodiments can incorporate any suitable combination of features from two or more drawings. [0044] Aspects of the present disclosure relate to an induction reflow system and the methods for manufacturing electrical contacts on a surface of a carrier board, such as a printed circuit board (PCB), by utilizing an induction reflow system. The electrical contacts can generally refer to terminals incorporated in the PCB, where these terminals can provide or be included in signal paths between electrical components integrated into the PCB. Such electrical contacts can be applied by incorporating a through-hole pin on each of a plurality of through-holes of the PCB. The induction reflow system can include a power supply and an induction coil. The power supply can generate alternating current (AC current) in various frequency ranges, for example, between 1 Megahertz (MHz) to 300 MHz. Such frequency ranges can include a high-frequency (HF) range, for example, between 3 MHz to 30 MHz and/or a very high frequency (VHF) range of 30 MHz – 300 MHz. The induction coil can generate a magnetic field when the coil receives the AC current from the power supply. This magnetic field can induce an eddy current on a solder pad, facilitating the assembly of solder joints on the PCB. [0045] In some aspects of the present disclosure, induction reflow can form a solder joint for a through-hole component or a surface mount component. For soldering through-hole components, the assembly methods may include positioning a pin (e.g., the electrical contact point of the PCB) within each of a plurality of through-hole of the PCB. For illustrative purposes, one or more electronic components may be positioned on the top side of the PCB, aligning each component’s contact point with a corresponding through-hole. The term “contact point” typically refers to a terminal that can provide electrical contact to the electronic component for electrical connection to signal line(s), such as copper signal lines, of the PCB. For instance, a solder pad, such as a through-hole pad, may be positioned within the hole to facilitate this electrical connection by soldering the through-hole pin. In these examples, the through-hole pin can be inserted into the through-hole (a hole embedded across the upper and lower side of the PCB), and the electronic component can be placed on the top side of the PCB in alignment with the through-hole pin. On the opposite side of the PCB (the bottom side), solder paste is applied to the solder pad within the through-hole. Subsequently, an induction coil can be positioned nearby, without physically touching, the solder pad on the bottom side of the PCB. Activation of the induction coil by a power supply can generate a magnetic field, which in turn induces a current in the solder pad. This current can heat the solder paste, causing it to melt and wick into the through-hole, thus forming a secure bond between the electronic component and the PCB. For example, the solder paste can be positioned on top of the solder pad, and the induction coil can apply a magnetic field on the solder pad. This magnetic field can induce an eddy current on the solder pad, where this current can cause heat to be generated from the solder pad, and thus, the solder paste can be melted. [0046] In some embodiments, the assembly methods disclosed in the present disclosure can be applied to assembling surface-mounted components onto a PCB. For example, solder can be applied on the PCB. In this example, a terminal (e.g., a pin) of a surface mount component can be located on the solder. Eddy current can be induced on the pin of the surface mount component, such as by placing an induction coil in proximity to the pin. In this example, the induced Eddy current can melt the solder paste. Even though the present disclosure illustrates examples of induction reflow for assembling a through-hole pin, any suitable principles and advantages of induction reflow disclosed herein can be used to solder surface-mounted components onto a PCB. [0047] A PCB layout can determine the specific position of each through-hole. Any suitable principles and advantages disclosed herein can be applied to any suitable PCB layouts. [0048] Generally described, inductive coupling between two conductors can be a method of wirelessly transferring energy from one conductor to another conductor. This technique utilizes magnetic fields to transmit the power between two conductors. For instance, an inductive coil that generates magnetic fields within a specific range can transfer the energy to another conductor in proximity to the inductive coil. [0049] In PCB assembly manufacturing, there can be technical challenges related to one or more of differently sized passive components, through-hole parts sustaining reflow temperature profiles, or special reflow processes related to large PCB assemblies. [0050] Differently sized passive components can have different thermal masses and heat up to a reflow temperature in different amounts of time. Certain PCB assemblies can include surface mount technology (SMT) components only, with both big SMT components (such as SMT film capacitors and/or inductors) that have a relatively large thermal mass and are relatively slow to heat up and reflow and relatively small SMT components that have much smaller thermal mass and can quickly reach reflow temperature. When running reflow on the whole PCB assembly, there can be non-uniform heating on the components of different sizes. It can be difficult to achieve good soldering quality on the big SMT components without overheating the small SMT components. [0051] Through-hole parts typically go through wave soldering because such components typically should not sustain a SMT reflow temperature profile. Example through hole parts include, but are not limited to, through-hole film capacitors, electrolytic capacitors, through-hole chokes and inductors. A wave soldering process for through-hole parts can add additional cost and cycle time in PCB assembly manufacturing. [0052] PCB assemblies that have sizes that are larger than typical SMT line capability can have a special reflow oven that adds manufacturing cost. Examples of such large PCB assemblies include PCB assemblies suitable for an induction reflow system. [0053] This disclosure provides a design of devices and manufacturing procedures for a PCB assembly manufacturing line to solder components a PCB with induction reflow. Induction heating can be used to reflow solder paste applied at component pads (e.g., copper component pads) on the PCB with the component pads exposed to a relatively high frequency magnetic field. For this process, high frequency power converters with air core inductors can be used. These converters can be part of the induction reflow station equipment. The air core inductors can be placed relatively close to the target component pads to create a localized high frequency magnetic field for induction reflow. This reflow process can be a selective soldering process of target parts using a loop of air core inductors, driven by a kilohertz (kHz,) megahertz (MHz) frequency, or a very high frequency (VHF) resonant circuit. Accordingly, the process can become a batch soldering process for all selective locations at one time. This is faster than conventional reflow processes and much lower in cost. This induction reflow soldering station can be either before or after a typical SMT oven, replacing a wave solder machine for selective soldering. [0054] In some instances, most or all of the components on the PCB can be soldered using the same type of solder paste. Accordingly, both large and small SMT components can be soldered using the same soldering material. The induction reflow disclosed herein can be applied to sealed part or non-sealed parts. [0055] Embodiments of the present disclosure provide technical solutions for assembling electronic components onto a PCB using an inductive coil. The inductive coil can generate a magnetic field when it receives AC current from a power supply. Positioned near the solder pad, the magnetic field induces a current directly in the solder pad itself and a metal pin of an electrical component (e.g., surface mount component or though-hole component) that is soldered onto the PCB. This induced current produces heat sufficient to melt the solder paste, allowing for the attachment of electronic components without direct external heating. In various embodiments, the size of the coil can be modified based on the area of the solder pad. Inductive reflow methods disclosed herein can form solder joints faster than other reflow methods. Inductive reflow methods disclosed herein can apply localized heating that can have less of an impact on other areas of a PCB including areas that can be susceptible to damage during reflow. [0056] The present disclosure provides electronic component assembly methods that utilize an induction reflow process. At the initiation of such a process, electronic components to be soldered are positioned on the PCB where solder paste has already been applied. During the reflow stage, one or more inductive coils are placed in close proximity to the solder paste. When the power supply initiates the generation of AC current, it is directed to the induction coil. Consequently, the coil can generate a magnetic field oriented perpendicular to the solder pads, which in turn induces eddy currents on the pads. These eddy currents lead to a localized increase in temperature, melting the solder paste and thereby securing the electronic component to the solder pad. [0057] In some embodiments, the systems and methods described herein may incorporate a flux concentrator. A flux concentrator can focus a magnetic field. This can direct the magnetic field towards and around the solder pads. By guiding the magnetic field emanating from the induction coil specifically to the solder pads, the flux concentrator can ensure that current is induced precisely in these areas. This targeted induction can allow for controlled heating, which can be finely tuned to melt only the solder paste without raising the temperature of the other regions or components on the PCB. This selective heating can be a significant advantage, as it can reduce and/or minimize the risk of thermal damage to adjacent components and areas during the soldering process. [0058] In certain examples, the power supply can generate AC current across a broad frequency spectrum, ranging from a few kHz to approximately 100 MHz. In these scenarios, the power supply can adaptively apply AC current at variable frequencies. For instance, to solder an electronic component in a shorter period of time, the power supply may generate AC current at a higher frequency. Conversely, if the electronic component is sensitive to heat, the power supply can operate at a lower frequency to accommodate this sensitivity. The AC current frequency can be supplied based on the solder pad area, electrical component’s pin size, induction coil size, and power specified for the soldering process. In these examples, the power supply can include any suitable power circuitry topology to provide this AC current in a desired frequency range. [0059] An inductive coil for reflow can have various shapes and/or numbers of windings. The shape can be determined based on the size of the soldering area and/or the shape of the soldering area. In addition, the power supply can supply power to one or a plurality of inductive coils. Thus, a plurality of electrical components can be soldered at once. [0060] Inductive reflow can be used to solder components to a PCB in a variety of applications. For example, the induction reflow system described herein can be applicable in the assembly of PCBs used in wireless chargers. Specifically, these chargers can be designed to wirelessly charge battery-operated vehicles, including electric cars, bicycles, boats, and similar vehicles. The durability of the PCB assembly can be significant for such applications, as the wireless chargers can produce high power outputs, potentially reaching up to 800 Volts. Consequently, it can be desirable for the PCB assembly to have robust electrical contacts that can withstand these intense power levels. Additionally, the wireless chargers can have mechanical resilience, especially in scenarios where vehicles might drive over them. The induction reflow system and the associated PCB assembly process disclosed herein can be capable of creating such durable electrical contact points. This process leverages the advantages of induction reflow to ensure that the assembled PCBs are suitable for use in these high-demand wireless charging applications. [0061] Although aspects of the present disclosure will be described with regard to illustrative components, interactions, and routines, one skilled in the relevant art will appreciate that one or more aspects of the present disclosure may be implemented in accordance with various environments, system architectures, customer computing device architectures, and the like. Similarly, references to specific devices, such as a battery, can be considered to be general references and not intended to provide additional meaning or configurations for the individual battery. Still, further, illustrations and exemplary configurations are not intended to be limited and should not be construed as limiting the scope of the present disclosure. Additionally, the examples are intended to be illustrative and should not be construed as limiting. [0062] FIG. 1A illustrates of an example of an induction reflow system 100 according to some embodiments. More specifically, the induction reflow system 100 can include a power supply 110 and an induction coil component 120. The power supply 110 and the induction coil component 120 can be connected via an electric connection 112. [0063] As illustrated in FIG. 1A, the induction coil component 120 can include an induction coil 122 and a cooling pad 124. As shown in FIG. 1A, the induction coil 122 can have two input terminals 122A and 122B. Each of these two input terminals 122A and 122B can be connected to the corresponding output terminal of the power supply 110 via the electric connection 112. For example, terminal 122A can be connected to the positive output terminal of the power supply 110, and the terminal 122B can be connected to a ground terminal of the power supply 110. In other examples, the terminal 122B can be connected to the positive output terminal of the power supply 110, and the terminal 122A can be connected to a ground terminal of the power supply 110. [0064] In some embodiments, the AC current can be applied between the terminals 122A and 122B. The AC current can pass through the induction coil 122, and a magnetic field can be generated by the induction coil 122. For example, a circular flux shape magnetic field can be generated surrounding the induction coil 122. In some examples, a cooling pad 124 can surround the terminals 122A and 122B of the induction coil 122. Alternatively, the induction coil 122 can be air-cooled in embodiments that do not include a cooling pad 124 or other cooling equipment. In some embodiments, the cooling pad 124 can be a liquid cooling tube. For example, such a liquid cooling tube can connect with an external liquid cooling device (not shown in FIG. 1A). The liquid cooling device can have a reservoir to store the liquid and be configured to supply the liquid to the cooling pad 124. [0065] The power supply 110 can generate AC current for inductive reflow. In some embodiments, the power supply 110 can include a DC-AC current inverter (not shown in FIG. 1A). In these embodiments, the power supply 110 can receive DC current from an energy source 202 (shown in FIGs. 2A-2C), such as from a battery or a battery pack, power line provided by a utility company, real-time power sources (e.g., solar cells or wind energy sources), stored energy cells, the like, or any suitable combination thereof. The power supply 110 can provide AC current having a frequency of at least 100 kilohertz (kHz). In some examples, the power supply 110 can generate a relatively high-frequency AC current with a resonant frequency in the MHz range. For example, the frequency range can be at least a frequency of 1 MHz, such as between 2 MHz to 10 MHz, between 2 MHz to 40 MHz, a high- frequency (HF) range, between 3 MHz to 30 MHz, or a very high frequency (VHF) range of 30MHz – 300MHz. To generate such a high-frequency AC current, the present application provides various power inverter topologies as described in FIGs. 2A-2C. [0066] FIG. 1B illustrates of an example of an induction reflow system 150 according to some embodiments. More specifically, the induction reflow system 150 can include a power supply 110 and a plurality of induction coil components 120-1 and 120-2. Any suitable number of induction coil components 120-1, 102-2 can be connected to a single power supply 110. The plurality of induction coil components 120-1 and 120-2 can concurrently form solder joints during induction reflow. The power supply 110 and each of the induction coil components 120-1 and 120-2 can be connected via an electric connection 112-1 and 112-2, respectively. The power supply 110 can provide AC power to each of the multitude of induction coil components 120-1 and 120-2. Each of the induction coil components 120-1 and 120-2 can include induction coil 122-1 or 122-2, the terminals 122A-1 and 122B-1 or 122A-2 and 122B-2, and the cooling pad 124-1 or 124-2, respectively. [0067] Each of the induction coil component 120-1 and 120-2 can concurrently form one or more solder joints connected to respective electronic components (e.g., one or more though-hole components, one or more surface mount components, etc.) positioned on a PCB. The induction coil component 120-1 can form a single solder joint or a plurality of solder joints, while the induction coil component 120-1 forms a single solder joint or a plurality of solder joints. In certain applications, the induction coil 120-1 and the induction coil 120-2 can have a similar shape and/or size. In some other applications, the induction coil 120-1 and the induction coil 120-2 can have a different shape and/or size. In addition, the number of the induction coil components can be determined based on specific applications, and the present disclosure does not limit the number of the induction coil components that can be connected to the power supply 110. [0068] FIGs. 2A-2C illustrate example inverter circuit topologies of the power supply 110 in induction reflow systems according to some embodiments. In some embodiments, these inverter circuitry topologies can generate high-frequency AC current. The high frequency AC current can be over 1 MHz. The high frequency AC current can have a frequency in a range from 1 MHz to 100 MHz, such as in a range from 1 MHz to 10 MHz, 2 MHz to 10 MHz, or 3 MHz to 30 MHz. In some applications, the high frequency AC current from the power supply 110 can have a very high frequency in a range from 30 MHz to 300 MHz. With higher frequency AC current, eddy currents can be increased on losses on a copper pad can be proportional to current times resistance squared. For example, as the frequency of the AC current increases (with the same magnitude of the AC current), the losses on the copper pad can be higher, which can be proportional to the resistance times current squared. Thus, resistance can be higher at higher frequencies due to skin depth, so the loss in the form of heat can be higher at higher frequencies. Each power supply 110 illustrated in FIGs.2A-2C can be configured with a different circuit topology, 210, 220, or 230, that can generate the high- frequency AC current. [0069] FIG. 2A illustrates an example induction reflow system 200A. As illustrated in FIG. 2A, the power supply 110 can include an inverter 210 having a class D topology. The inverter 210 can receive input DC power from an energy source 202. The output of the power supply 110 can be connected with the induction coil 122 via the terminals 122A and 122B. [0070] As illustrated in FIG. 2A, the DC current can be generated from the energy source 202 and can be inverted into AC current using switches 212 and 214. These switches 212 and 214 can be field effect transistors (FETs), such a metal-oxide-semiconductor field- effect transistors (MOSFETs). In various embodiments, controlling the switching sequence of each switch 212 and 214 can generate the AC current. In these embodiments, the frequency of the generated AC current can be related to the sequences applied to each of the switches 212 and 214. For example, if the switching speed (e.g., determined based on the sequences applied to switches 212 and 214) is faster, the frequency of the AC current supplied to the induction coil 122 can have a higher frequency. [0071] FIG. 2B illustrates an example of an induction reflow system 200B. As illustrated in FIG. 2B, the power supply 110 can include an inverter 220 having a class E topology. The inverter 220 can receive input DC power from the energy source 202 and provide AC current to the induction coil 122. [0072] As illustrated in FIG. 2B, DC current provided by the energy source 202 and can be inverted into AC current by using a switch 222. The class E topology also includes a resonant circuit. The switch 222 can be a FET, such as a MOSFET. In various embodiments, controlling the switching sequence of the switch 222 can generate the AC current. In these embodiments, the frequency of the generated AC current can be related to the sequence applied to the switch 222. In some embodiments, the class E topology included in the inverter 220B can be configured to generate the AC current having a frequency in a range from kilohertz to a VHF frequency range depending on the power device selection and the inductor and capacitor values. For example, for an operating frequency of 10 MHz, the inductor 122 can have an inductance in the range of a few hundreds of nH and the capacitor 228A can have a capacitance in the range of a few hundreds of pF. [0073] FIG. 2C illustrates an example of an induction reflow system 200C. As illustrated in FIG. 2C, an inverter 230 having class ĭ2 topology can be included in the power supply 110 and generate AC current with relatively high operating frequency. The inverter 230 can receive input DC power from the energy source 202 and output AC current to the induction coil 122. [0074] As illustrated in FIG.2C, the inverter 230 can include a switch 232 and also a resonant tank 236. In various embodiments, controlling the switching sequence of switch 232 can generate the AC current. Furthermore, the resonant tank 236 can be configured to eliminate the 2^nd harmonic in the voltage waveform, so that the voltage stress of the switching device (e.g., switch 232) can be reduced. For example, the resonant tank 236 can tune harmonics of the voltage waveform generated at the output of the switch 232 (e.g., drain terminal 232A of the MOSFET) to reduce the output voltage stress of the switch 232. [0075] FIG.3 illustrates an example induction reflow system performing induction reflow on PCB assembly 300 according to an embodiment. As illustrated in FIG. 3, a PCB 310 can include one or more solder pads. In some embodiments, the solder pad can be through- hole pad. In some other examples, the solder pad can be a surface mount pad that can provide electrical contact points on the PCB where surface-mounted components can be assembled. The solder pads can provide a connection point to an electrical component, such as a though- hole component, a surface-mount technology (SMT) component, an integrated circuit, or any other suitable electronic component. For example, each through-hole 312 (e.g., using a solder pad in the through-hole 312) can facilitate an electrical connection across the PCB 310, linking its top and bottom surfaces. In certain instances, electrical components are mounted onto the PCB 310 by inserting their terminals into the through-holes 312. The placement of these terminals may be on either side of the PCB 310—for instance, the top or bottom surface— depending on the design specifications. To secure a through-hole component’s terminal to the PCB 310, solder paste is applied to the opposite side, which then flows into and through the through-hole 312 during the soldering process, using the induction reflow system. If the solder pad is applied for a surface mount component, the solder paste can be applied to the same side of the PCB as the surface mount component. As depicted in FIG.3, the PCB 310 can include a plurality of through-holes 312 and the through-hole pins 314. The number and location of this multitude of through-holes 312 and the through-hole pins 314 can be determined based on the PCB 310 layouts designed for specific applications. Any suitable numbers and locations of the through-holes 312 and the through-hole pins 314 can be implemented. [0076] In various embodiments, a through-hole pin 314 may be soldered into the through-hole 312 by using the induction reflow system as disclosed herein. The through-hole pin 314 can establish an electrical contact point within the PCB 310. This through-hole pin 314 can serve as an electrical contact point on the PCB 310. For instance, during the assembly of an electrical component onto the PCB, the component’s electrical contact terminals are aligned with and connected to the corresponding through-hole pin 314, in accordance with the predetermined layout. [0077] In some embodiments, the through-hole pin 314 may be soldered into the through-hole 312 utilizing an induction reflow system. In these implementations, the through- hole pin 314 can be first inserted into the through-hole 312. Subsequently, solder paste (which is not shown in FIG. 3), can be applied beneath the solder pad 318. Atop the solder pad 318, a flux concentrator 320 can be positioned. The flux concentrator 320 can focus the magnetic field produced by the induction coil 122 onto the solder pad 318. Additionally, the flux concentrator 320 includes a central hole 322, to facilitate this process. [0078] As depicted in FIG.3, the induction coil 122 can generate a magnetic field. This magnetic field can be produced by an AC current flowing through the induction coil 122. For example, the current can enter through terminal 122A, moves through the coil, and exits via terminal 122B. Alternatively, the AC current could flow in through terminal 122B, pass through the induction coil 122, and exit through terminal 122C. The present does not limit the direction of the AC current, and the direction of flow can be determined based on specific applications. [0079] The AC current flowing within the induction coil 122 can induce a magnetic field with circular flux lines that are perpendicular to the plane of the solder pad 318. The solder pad 318, being made of a conductive material, interacts with this changing magnetic field. The variation in the magnetic flux generates eddy currents on the surface of the solder pad 318. These eddy currents produce heat on the surface of the solder pad 318, which in turn causes the solder paste—positioned underneath the solder pad 318—to melt and flow into the through-hole 312, thereby securing the through-hole pin 314 within the through-hole 312. [0080] The strength of the eddy currents induced in the solder pad 318 can be related to the frequency of the AC current passing through the induction coil 122. Specifically, the strength of the eddy current loss should increase with frequency, causing different temperature rise rates. Thus, the reflow temperature profile on the solder pad 318 can be controlled by changing AC current frequency and/or power level from the power supply 110. Therefore, by controlling the frequency of the AC current from the power supply 110, the temperature of the solder pad 318 can be regulated. This control over temperature can be beneficial for achieving the desired soldering results without damaging any components or materials involved in the process. In some cases, the cooling pad 124 can dissipate heat generated on the terminals 122A and 122B. Thus, the AC current can be continuously supplied to the induction coil 122 without affecting the heat at terminals 122A and 122B. [0081] FIG. 4 illustrates an example of a cross-sectional view of a PCB assembly 300 during induction reflow. As shown in FIG. 4, the PCB 310 can incorporate through-hole 312, which extends from the top surface to the bottom surface of the PCB 310. The through- hole pin 314 can be inserted through the through-hole 312. At the top of the through-hole 312, solder paste 402 can be applied. In various examples, this solder paste 402 can melt and flow into the space between the through-hole 312 and the through-hole pin 314, thus securing the through-hole pin 314 within the through-hole 312. [0082] As further shown in FIG. 4, the solder pad 318 can be situated on the PCB 310. Solder paste 402 can be applied over the solder pad 318. In some cases, the solder pad 318 can be extended to the opposite side of the PCB 310, passing through the through-hole 312. For example, as illustrated in FIG. 4, the solder pad 318 can be located on the top 310A and bottom 310B sides of the PCB by passing through the through-hole 312. The solder paste 402 can be applied on the bottom side 310B, such as underneath of the solder pad 318 located in the bottom side 310B.In some embodiments, when heat is applied to the solder paste 402, it melts. Surrounding the solder pad 318 (e.g., on the top side 310A of the PCB 310) can be the flux concentrator 320. In some implementations, this flux concentrator 320 can have a central hole 322 (as shown in FIG. 3), allowing the solder pad 318 located on the top side 310A to be directly exposed to the magnetic field 410. Utilizing the flux concentrator 320 can focus the magnetic field 410 on the solder pad 318. This targeted induction of the magnetic field can reduce or eliminate overheating and/or damage to other components on the PCB 310. [0083] Furthermore, as illustrated in FIG.4, an AC current from the power supply 110, can flow to the induction coil 122 via terminal 122A. As described with respect to FIG. 4, this AC current can generate a magnetic field 410, around the induction coil 122. This magnetic field can induce eddy currents on the surface of the solder pad 318. The resulting eddy currents can elevate the temperature of the solder pad 318. Consequently, the heat generated on the solder pad 318 can melt the solder paste 402, allowing it to flow into and fill the gap between the through-hole pin 314 and the through-hole 312, thereby completing the soldering process. [0084] FIG. 5 illustrates an example of a PCB assembly 500, where the induction reflow system that includes an induction coil with a solenoid shape is used for inductive reflow. As illustrated, the AC current from the power supply 110 (e.g., as shown in FIG. 4) can flow from terminal 122A through the solenoid-shaped induction coil 522 and exit via terminal 122B. In this configuration, the solenoid-shaped induction coil 522 can generate a magnetic field 510, which is oriented perpendicular to both the solder pad 318 and the flux concentrator 320. [0085] The top surface of the solder pad 318 can be exposed through the hole 322 in the flux concentrator 320 (as depicted in FIG.3). Consequently, the magnetic field 510 can induce eddy currents on the solder pad 318. These eddy currents can generate sufficient heat to melt the solder paste 402 (illustrated in FIG.4) that is situated on top of the solder pad 318. Once melted, the solder paste 402 flows into and fills the space between the through-hole pin 314 and the through-hole 312, thereby creating a secure solder joint. [0086] FIG. 6A illustrates an example of a PCB assembly 600A, where an induction reflow system can solder multiple through-hole pins 314 simultaneously. As shown in FIG. 6A, the PCB 310 can include multiple solder joints 630 that each solder joint can include a through-hole pins 314. The induction coil 622 can have a solenoid shape and encircles these through-hole pins 314. Even though the solder joints 630 is illustrated as though-hole pin type, the solder joints 630 can be a joint for soldering a surface mount component. The present application does not limit the types of the solder joints 630. [0087] In some implementations, an AC current from the power supply 110 (e.g., as shown in FIG. 4) is directed into the solenoid-shaped induction coil 622 via terminal 122A and exits through terminal 122B. Alternatively, the current may enter through terminal 122B, traverse the solenoid-shaped induction coil 622, and exit via terminal 122A. This AC current can generate a magnetic field around the induction coil 622. The magnetic field, in turn, induces eddy currents on the surfaces of the solder pads 318. [0088] Consequently, the magnetic field produced by the single flow of AC current through the induction coil 622 can effectively induce sufficient heat across solder pads 318 associated with the multiple through-hole pins 314 to melt the solder and facilitate the soldering process for a plurality of pins simultaneously. [0089] FIG.6B illustrates an example of a PCB assembly 600B, where an induction reflow system can form a plurality of joints according to an embodiment. As illustrated in FIG.6B, the PCB 310 can include a plurality of soldering joints. As illustrated in FIG.6B, the induction coil 622 can concurrently form the solder joints located inside the illustrated induction coil 622. For example, as illustrated in FIG.6B, the induction coil 622 can generate a magnetic field and induce Eddy currents on the solder pads 318 inside the induction coil 622. In some embodiments, multiple induction coils 122-1, 122-2, 122-3 can solder a corresponding soldering joint 630 simultaneously. In some instances, the induction coil 622, the induction coils 122-1 to 122-3, and the multi-turn induction coil 652 can simultaneously solder the solder joints 630. These induction coils, 622, 122-1 to 122-3, and 652 can receive AC power from a single power supply in certain embodiments. The induction coils, 622, 122-1 to 122-3, and 652 can receive AC power from two or more power supplies in some other embodiments. In some examples, the power supplied to two or more of the coils, 622, 122-1 to 122-3, 652 can be different. Furthermore, even though the soldering joints 630 are illustrated as soldering to though-hole pins 314, this illustration is provided as an example. The present does not limit the types of soldering joint 630, and each of the coils 622, 122-1 to 122-3, and 652 can solder any suitable electronic components. In addition, any suitable number of induction coils can be powered concurrently for induction reflow. [0090] FIGs. 7A – 7F illustrate various examples of the induction coils in accordance with the embodiments disclosed herein. For example, the induction coil can be formed with a wide solenoid coil, as shown in FIG.7A. The induction coil can be formed with a compact solenoid coil, as shown in FIG. 7B. The induction coil can also be formed with a spiral having multiple turns, as shown in FIG.7C. The induction coil can include a single turn, such as shown in FIGs.7D to 7F. Furthermore, the shape of the induction coil can be modified based on the area or shape of the solder pad, as illustrated in FIGs.7D, 7E, and 7F. Single turn coils have a desirable performance with high current excitation in certain applications. [0091] FIG. 8 illustrates an induction coil 122 forming a solder joint for an electronic component on a PCB 310. In FIG. 8, the electronic component is a though-hole component. Some or all of the soldering processes of the PCB assembly can utilize an induction reflow process as described in the present disclosures. [0092] In some embodiments, the induction reflow processes and systems disclosed herein can be used in assembling a PCB component of a vehicle charger and/or a vehicle pad for wireless charging. Such a PCB component can include electronic components including one or more capacitors, one or more inductors, and one or more switching devices (e.g., field effect transistors). The electronic components on the PCB can be included in a wireless charging pad configured to supply 400 Volts of direct current power from wirelessly received alternating current power. The electronic components on the PCB can be included in a wireless charging pad configured to supply 800 Volts of direct current power from wirelessly received alternating current power. Additional Embodiments [0093] In the foregoing specification, the disclosure has been described with reference to specific embodiments. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the disclosure. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense. [0094] Indeed, although this disclosure is in the context of certain embodiments and examples, it will be understood by those skilled in the art that the inventions extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the inventions and equivalents thereof. In addition, while several variations of the embodiments have been shown and described in detail, other modifications, which are within the scope of this disclosure, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the disclosure. It should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to form varying modes of the embodiments disclosed herein. Any methods disclosed herein need not be performed in the order recited. Thus, it is intended that the scope of the disclosure should not be limited by the particular embodiments described above. [0095] It will be appreciated that the systems and methods of the disclosure each have several innovative aspects, no single one of which is solely responsible or required for the desirable attributes disclosed herein. The various features and processes described above may be used independently of one another or may be combined in various ways. All possible combinations and subcombinations are intended to fall within the scope of this disclosure. [0096] Certain features that are described in this specification in the context of separate embodiments also may be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment also may be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination may in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. No single feature or group of features is necessary or indispensable to each and every embodiment. [0097] It will also be appreciated that conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment. The terms “comprising,” “including,” “having,” and the like are synonymous and are used inclusively, in an open- ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. In addition, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. In addition, the articles “a,” “an,” and “the” as used in this application and the appended claims are to be construed to mean “one or more” or “at least one” unless specified otherwise. Similarly, while operations may be depicted in the drawings in a particular order, it is to be recognized that such operations need not be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example processes in the form of a flowchart. However, other operations that are not depicted may be incorporated in the example methods and processes that are schematically illustrated. For example, one or more additional operations may be performed before, after, simultaneously, or between any of the illustrated operations. Additionally, the operations may be rearranged or reordered in other embodiments. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems may generally be integrated together in a single software product or packaged into multiple software products. Additionally, other embodiments are within the scope of the following claims. In some cases, the actions recited in the claims may be performed in a different order and still achieve desirable results. [0098] Further, while the methods and devices described herein may be susceptible to various modifications and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the disclosure is not to be limited to the particular forms or methods disclosed, but, to the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the various implementations described and the appended claims. Further, the disclosure herein of any particular feature, aspect, method, property, characteristic, quality, attribute, element, or the like in connection with an implementation or embodiment can be used in all other implementations or embodiments set forth herein. Any methods disclosed herein need not be performed in the order recited. The methods disclosed herein may include certain actions taken by a practitioner; however, the methods can also include any third-party instruction of those actions, either expressly or by implication. The ranges disclosed herein also encompass any and all overlap, sub-ranges, and combinations thereof. Language such as “up to,” “at least,” “greater than,” “less than,” “between,” and the like includes the number recited. Numbers preceded by a term such as “about” or “approximately” include the recited numbers and should be interpreted based on the circumstances (e.g., as accurate as reasonably possible under the circumstances, for example ±5%, ±10%, ±15%, etc.). Phrases preceded by a term such as “substantially” include the recited phrase and should be interpreted based on the circumstances (e.g., as much as reasonably possible under the circumstances). For example, “substantially constant” includes “constant.” Unless stated otherwise, all measurements are at standard conditions, including temperature and pressure. [0099] As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: A, B, or C” is intended to cover: A, B, C, A and B, A and C, B and C, and A, B, and C. Conjunctive language such as the phrase “at least one of X, Y and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be at least one of X, Y or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require at least one of X, at least one of Y, and at least one of Z to each be present. The headings provided herein, if any, are for convenience only and do not necessarily affect the scope or meaning of the devices and methods disclosed herein. [0100] Accordingly, the claims are not intended to be limited to the embodiments shown herein but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein. [0101] Many variations and modifications may be made to the above-described embodiments, the elements of which are to be understood as being among other acceptable examples. All such modifications and variations are intended to be included herein within the scope of this disclosure. The foregoing description details certain embodiments. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the systems and methods can be practiced in many ways. As is also stated above, it should be noted that the use of particular terminology when describing certain features or aspects of the systems and methods should not be taken to imply that the terminology is being re-defined herein to be restricted to including any specific characteristics of the features or aspects of the systems and methods with which that terminology is associated. [0102] Many other variations than those described herein will be apparent from this disclosure. For example, depending on the embodiment, the processor disclosed herein can perform various processing scheme based on moving object detection data received from object detection sensor(s), as disclosed herein. [0103] The moving object detection can generally refer to living object detection. For example, the living object, such as human and animal, may able to move or change location. [0104] The various illustrative logical blocks and modules described in connection with the embodiments disclosed herein can be implemented or performed by a machine, such as a processing unit or processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A processor can be a microprocessor, but in the alternative, the processor can be a controller, microcontroller, or state machine, combinations of the same, or the like. A processor can include electrical circuitry configured to process computer-executable instructions. In another embodiment, a processor includes an FPGA or other programmable device that performs logic operations without processing computer-executable instructions. A processor can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. Although described herein primarily with respect to digital technology, a processor may also include primarily analog components. A computing environment can include any type of computer system, including, but not limited to, a computer system based on a microprocessor, a mainframe computer, a digital signal processor, a portable computing device, a device controller, or a computational engine within an appliance, to name a few.

Claims

WHAT IS CLAIMED IS: 1. A method of assembling one or more electrical components on a printed circuit board (PCB) with induction reflow, the method comprising: providing alternating current power to a plurality of induction coils; and concurrently transmitting magnetic fields from the plurality of induction coils to solder material on the PCB to form a plurality of solder joints on the PCB.

2. The method of Claim 1, wherein a single power source provides the alternating current power to the plurality of induction coils.

3. The method of Claim 1, wherein a first induction coil of the plurality of induction coils forms at least two of the plurality of solder joints.

4. The method of Claim 1, wherein the alternating current has a frequency of at least 1 megahertz.

5. The method of Claim 4, wherein the frequency is in a range from 2 megahertz to 40 megahertz.

6. The method of Claim 1, wherein a magnetic field of a first induction coil of the plurality of induction coils is transmitted to the solder material through a flux concentrator.

7. The method of Claim 1, wherein the induction coil is a single turn coil.

8. The method of Claim 1, wherein a first solder joint of the plurality of solder joints is electrically connected to a surface mount component positioned on the PCB.

9. The method of Claim 1, wherein a first solder joint of the plurality of solder joints is electrically connected to a through-hole component.

10. The method of Claim 1, wherein an electronic component on the PCB is included in a wireless charging pad configured to supply 400 Volts of direct current power from wirelessly received alternating current power, and wherein at least one of the solder joints is connected to the electronic component.

11. A method of assembling one or more electrical components on a printed circuit board (PCB) with induction reflow, the method comprising: providing alternating current power to an induction coil; and transmitting a magnetic field from the induction coil to solder material on the PCB to form a plurality of solder joints on the PCB.

12. The method of Claim 11, further comprising while transmitting the magnetic field from the induction coil, transmitting a second magnetic field from a second induction coil to form at least one additional solder joint on the PCB.

13. The method of Claim 12, wherein a single power supply provides alternating current power to the induction coil and the second induction coil.

14. The method of Claim 11, wherein the alternating current has a frequency of at least 1 meghertz.

15. A method of assembling one or more electrical components on a printed circuit board (PCB) with induction reflow, the method comprising: providing alternating current power to an induction coil, the alternating current power having a frequency of greater than 1 megahertz; and transmitting a magnetic field from the induction coil to solder material on the PCB to form a solder joint on the PCB.

16. The method of Claim 15, wherein the transmitting the magnetic field from the induction coil forms a plurality of solder joints, the plurality of solder joints including the solder joint.

17. The method of Claim 15, wherein the frequency is in a range from 2 megahertz to 10 megahertz.

18. The method of Claim 15, wherein the frequency is in a range from 2 megahertz to 40 megahertz.

19. An induction reflow system comprising: a power supply configured to generate alternating current; and a plurality of induction coils connected to the power supply, the plurality of induction coils configured to apply magnetic fields to inductively reflow solder to concurrently from a plurality of solder joints on a printed circuit board.

20. The induction reflow system of Claim 19, further comprising a flux concentrator to focus the magnetic field applied by the induction coil for forming the solder joint.

21. The induction reflow system of Claim 19, wherein the alternating current has a frequency of at least 1 megahertz.

22. The induction reflow system of Claim 19, wherein the alternating current has a frequency in a range from 2 megahertz to 40 megahertz.

23. The induction reflow system of Claim 19, wherein the power supply includes an inverter configured to generate the alternating current from direct current.

24. The induction reflow system of Claim 19, wherein a first induction coil of the plurality of induction coils has a single turn.