Induction Reflow of Printed Circuit Board Assemblies

Abstract

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

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of U.S. Provisional Application No. 63 / 487,568, filed February 28, 2023, entitled "INDUCTION REFLOW OF PRINTED CIRCUIT BOARD ASSEMBLY," the entire disclosure of which is incorporated herein by reference in its entirety for all purposes.

[0002] FIELD OF THE DISCLOSURE The present disclosure generally relates to electronic assembly systems and methods for assembling electronic components using induction reflow. [Background technology]

[0003] In electronic component assembly, various electronic components can be assembled onto a printed circuit board (PCB). The assembly process can include the use of solder paste. The solder paste can be precisely applied to designated pads on the PCB surface, arranged according to the PCB's specific layout. Once the solder paste is in place, electronic components can be placed directly onto the corresponding paste-coated pads. The electronic components are then firmly secured to the PCB by a heating process, which melts the solder paste. This melting causes the solder to flow, forming a solid bond between the component and the pad on the PCB. Reflow can be performed in various manufacturing processes for assembling electronic components onto PCBs. In general, improved reflow techniques are desirable. Summary of the Invention

[0004] Each claimed innovation has 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 the disclosure will now be briefly described.

[0005] One aspect of the present disclosure is a method for assembling one or more electrical components on a printed circuit board (PCB), the method including supplying AC power to multiple induction coils and simultaneously transferring magnetic fields from the multiple induction coils to a solder material on the PCB to form multiple solder joints on the PCB.

[0006] In one embodiment, a single power supply can provide AC power to multiple induction coils.

[0007] In one embodiment, a first induction coil of the plurality of induction coils is capable of forming at least two of the plurality of solder joints.

[0008] In one embodiment, the AC power may have a frequency of at least 1 megahertz.

[0009] In one embodiment, the frequency of the AC power may be in the range of 2 megahertz to 40 megahertz.

[0010] In one embodiment, the magnetic field of a first induction coil of the plurality of inductions can be transmitted to the solder material through a magnetic flux concentrator.

[0011] In one embodiment, the induction coil may be a single turn coil.

[0012] In one embodiment, a first solder joint of the plurality of solder joints may be electrically connected to a surface mount component disposed on a PCB.

[0013] In one embodiment, the solder joints may be electrically connected to surface mount components located on a 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, the electronic components on the PCB can be included in a wireless charging pad configured to provide 400 volts DC power from wirelessly received AC power, and at least one of the solder joints can be connected to the electronic components.

[0016] Another aspect of the present disclosure is a method for assembling one or more electrical components on a printed circuit board (PCB) using induction reflow, the method including supplying AC power to an induction coil and transmitting a magnetic field from the induction coil to a solder material on the PCB to form a plurality of solder joints on the PCB.

[0017] In one embodiment, the method may 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 may provide AC power to the induction coil and the second induction coil.

[0019] In one embodiment, the alternating current may have a frequency of at least 1 megahertz.

[0020] Another aspect of the present disclosure is a method for assembling one or more electrical components on a printed circuit board (PCB) using induction reflow. The method includes supplying AC power to an induction coil and transmitting a magnetic field from the induction coil to a solder material on the PCB to form a solder joint on the PCB. The AC power has a frequency greater than 1 megahertz. In one embodiment, transmitting a magnetic field from an induction coil can form a plurality of solder joints, the plurality of solder joints comprising solder joints. In one embodiment, the frequency may be in the range of 2 megahertz to 10 megahertz.In one embodiment, the frequency may be in the range of 2 megahertz to 40 megahertz.

[0021] Another aspect of the present disclosure is an induction reflow system including a power supply and an induction coil connected to the power supply. The power supply is configured to generate alternating current having a frequency greater than 1 megahertz. The induction coil is sized to surround one or more electronic components disposed on a printed circuit board. Further, the induction coil is configured to apply a magnetic field to inductively reflow solder from at least one solder joint connected to at least one of the one or more electronic components.

[0022] In one embodiment, transmitting a magnetic field from the induction coil forms a plurality of solder joints, the plurality of solder joints comprising solder joints.

[0023] In one embodiment, the alternating current may have a frequency in the range of 2 megahertz to 10 megahertz.

[0024] In one embodiment, the alternating current may have a frequency in the range of 2 megahertz to 40 megahertz.

[0025] Another aspect of the present disclosure is an induction reflow system including a power supply configured to generate an alternating current and a plurality of induction coils configured to apply a magnetic field to inductively reflow solder from a plurality of solder joints on a printed circuit board simultaneously.

[0026] In one embodiment, the induction reflow system may further comprise a magnetic flux concentrator for concentrating the magnetic field applied by the induction coil to form the solder joint.

[0027] In one embodiment, the alternating current may have a frequency of at least 1 megahertz.

[0028] In one embodiment, the frequency of the alternating current may be in the range of 2 megahertz to 40 megahertz.

[0029] In one embodiment, the power supply may include an inverter configured to generate 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 all such advantages may necessarily be achieved in accordance with any particular embodiment. Thus, the innovations may be embodied or implemented to achieve or optimize one advantage or advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. [Brief explanation of the drawings]

[0032] These and other features, aspects, and advantages of the present disclosure will be described with reference to drawings of certain embodiments that are intended to illustrate, but not limit, the disclosure. It should be understood that the accompanying drawings, which are incorporated into and constitute a part of this specification, are for the purpose of illustrating the concepts disclosed herein and may not be to scale.

[0033] [Figure 1A] FIG. 1 illustrates an example of an induction reflow system according to some embodiments.

[0034] [Figure 1B] FIG. 1 illustrates an example of an induction reflow system having multiple induction coils according to some embodiments.

[0035] [Figure 2A] 1 illustrates various examples of inverter circuit topologies according to some embodiments. [Figure 2B] 1 illustrates various examples of inverter circuit topologies according to some embodiments. [Figure 2C]1 illustrates various examples of inverter circuit topologies according to some embodiments.

[0036] [Figure 3] 1 illustrates an example of an induction reflow system for performing induction reflow on a PCB assembly according to some embodiments.

[0037] [Figure 4] 1 illustrates an example of a cross-sectional view of a PCB assembly during induction reflow, according to some embodiments.

[0038] [Figure 5] 1 illustrates an example of a PCB assembly having a solenoid-shaped induction coil used for induction reflow, according to some embodiments.

[0039] [Figure 6A] 1 illustrates an example of a PCB assembly according to some embodiments.

[0040] [Figure 6B] 1 illustrates an example of a PCB assembly in which an induction reflow system can form multiple solder joints, according to some embodiments.

[0041] [Figure 7A] 1 illustrates various induction coils for induction reflow according to some embodiments. [Figure 7B] 1 illustrates various induction coils for induction reflow according to some embodiments. [Figure 7C] 1 illustrates various induction coils for induction reflow according to some embodiments. [Figure 7D] 1 illustrates various induction coils for induction reflow according to some embodiments. [Figure 7E] 1 illustrates various induction coils for induction reflow according to some embodiments. [Figure 7F] 1 illustrates various induction coils for induction reflow according to some embodiments.

[0042] [Figure 8] 1 illustrates an example of a PCB assembly in which solder joints are formed by induction reflow, according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0043] The following detailed description of certain embodiments presents various descriptions of specific embodiments. However, the innovations described herein can be embodied in many different ways, for example, as defined and encompassed by the claims. This description refers to the drawings, in which like reference numbers and / or terminology can indicate identical or functionally similar elements. It will be understood that the elements illustrated in the drawings are not necessarily drawn to scale. It will also be understood that certain embodiments can include more elements than and / or a subset of the elements illustrated in the drawings. Furthermore, 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 a method for fabricating electrical contacts on a surface of a carrier substrate, such as a printed circuit board (PCB), by utilizing the induction reflow system. Electrical contacts generally refer to terminals incorporated into the PCB, which may provide or be included in signal paths between electrical components incorporated into the PCB. Such electrical contacts may be applied by incorporating through-hole pins into each of a plurality of through-holes in the PCB. The induction reflow system may include a power supply and an induction coil. The power supply may generate alternating current (AC current) in various frequency ranges, for example, from 1 megahertz (MHz) to 300 MHz. Such frequency ranges may include, for example, a high frequency (HF) range from 3 MHz to 30 MHz and / or a very high frequency (VHF) range from 30 MHz to 300 MHz. The induction coil may generate a magnetic field when the coil receives AC current from the power supply. This magnetic field may induce eddy currents in the solder pads, facilitating assembly of solder joints on the PCB.

[0045] In some embodiments of the present disclosure, induction reflow can form solder joints for through-hole or surface-mount components. To solder through-hole components, the assembly method can include placing pins (e.g., electrical contacts of the PCB) in each of a plurality of through-holes in a PCB. For illustrative purposes, one or more electronic components can be placed on the top surface of the PCB, with the contacts of each component aligned with a corresponding through-hole. The term "contact" typically refers to a terminal that can provide electrical contact to the electronic component for electrical connection to a signal line, such as a copper signal line, of the PCB. For example, a solder pad, such as a through-hole pad, can be placed in 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 top and bottom sides 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 other side (bottom side) of the PCB, solder paste is applied to the solder pads in the through-holes. An induction coil can then be placed near the solder pads on the bottom side of the PCB without physically contacting them. The activation of the induction coil by a power source can generate a magnetic field, which induces a current in the solder pad. This current heats the solder paste, causing it to melt and be drawn into the through-hole, thus forming a secure bond between the electronic component and the PCB. For example, solder paste can be placed on a solder pad, and the induction coil can apply a magnetic field to the solder pad. This magnetic field can induce eddy currents in the solder pad, which can generate heat from the solder pad, thereby melting the solder paste.

[0046] In some embodiments, the assembly methods disclosed in the present disclosure can be applied to assembling surface mount components on a PCB. For example, solder can be applied to a PCB. In this example, terminals (e.g., pins) of the surface mount component can be placed on the solder. Eddy currents can be induced in the pins of the surface mount component, such as by placing an induction coil near the pins. In this example, the induced eddy currents can melt the solder paste. While the present disclosure provides an example of induction reflow for assembling through-hole pins, any suitable principles and advantages of induction reflow disclosed herein can be used to solder surface mount components onto a PCB.

[0047] The PCB layout may dictate the specific location of each through-hole. Any suitable principles and advantages disclosed herein may be applied to any suitable PCB layout.

[0048] Generally speaking, inductive coupling between two conductors can be a method of wirelessly transferring energy from one conductor to another. This technique utilizes magnetic fields to transfer power between the two conductors. For example, an induction coil that generates a magnetic field within a certain range can transfer energy to another conductor in close proximity to the induction coil.

[0049] In PCB assembly manufacturing, there may be technical challenges associated with one or more of different sized passive components, through-hole components maintaining reflow temperature profiles, or special reflow processes associated with large PCB assemblies.

[0050] Passive components of different sizes can have different thermal masses and heat to reflow temperature in different times. A particular PCB assembly may include only surface mount technology (SMT) components, with both large SMT components (such as SMT film capacitors and / or inductors) that have a relatively large thermal mass and heat and reflow relatively slowly, and smaller SMT components that have a much smaller thermal mass and can reach reflow temperature more quickly. Performing reflow on the entire PCB assembly can result in uneven heating of components of different sizes. Achieving good soldering quality on large SMT components without overheating the small SMT components can be difficult.

[0051] Through-hole components typically undergo wave soldering because they cannot withstand the SMT reflow temperature profile. Examples of through-hole components include, but are not limited to, through-hole film capacitors, electrolytic capacitors, through-hole chokes, and inductors. The wave soldering process for through-hole components can add additional cost and cycle time to PCB assembly manufacturing.

[0052] PCB assemblies larger than typical SMT line capabilities may require special reflow ovens, which adds to manufacturing costs. Examples of such large PCB assemblies include PCB assemblies suitable for induction reflow systems.

[0053] This disclosure provides a design of a device and manufacturing procedure for a PCB assembly manufacturing line for soldering PCBs to components by induction reflow. Induction heating can be used to reflow solder paste applied to component pads (e.g., copper component pads) on a PCB, exposing the component pads to a relatively high-frequency magnetic field. High-frequency power converters with air-core inductors can be used for this process. 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 generate a localized high-frequency magnetic field for induction reflow. This reflow process can be a selective soldering process for target components using a loop of air-core inductors driven by a kilohertz (kHz), megahertz (MHz) frequency, or very high frequency (VHF) resonant circuit. Therefore, this process can be a batch soldering process for all selected locations at once. This is faster and much less expensive than traditional reflow processes. This induction reflow soldering station can be either before or after a typical SMT furnace, replacing a wave soldering machine for selective soldering.

[0054] In some cases, most or all of the components on a PCB can be soldered using the same type of solder paste, allowing large and small SMT components to be soldered with the same solder material. The induction reflow of the present disclosure can be applied to sealed or unsealed parts.

[0055] Embodiments of the present disclosure provide a technical solution for assembling electronic components on a PCB using an induction coil. The induction coil can generate a magnetic field when it receives AC current from a power source. The magnetic field, placed near a solder pad, directly induces current in the solder pad itself and in the metal pins of electrical components (e.g., surface-mount or through-hole components) soldered to the PCB. This induced current generates sufficient heat to melt the solder paste, allowing the electronic component to be attached without direct external heating. In various embodiments, the size of the coil can be varied based on the area of ​​the solder pad. The induction reflow method disclosed herein can form solder joints faster than other reflow methods. The induction reflow method disclosed herein can apply localized heating, which can have less impact on other areas of the PCB, including areas that may be susceptible to damage during reflow.

[0056] This disclosure provides an electronic component assembly method utilizing an induction reflow process. At the beginning of such a process, the electronic component to be soldered is placed on a PCB that already has solder paste applied. During the reflow phase, one or more induction coils are placed in close proximity to the solder paste. When a power supply begins generating AC current, it is directed at the induction coils. As a result, the coils can generate a magnetic field oriented perpendicular to the solder pads, which in turn induces eddy currents in the pads. These eddy currents result in a localized temperature increase, melting the solder paste and thereby securing the electronic component to the solder pads.

[0057] In some embodiments, the systems and methods described herein can incorporate a magnetic flux concentrator. The magnetic flux concentrator can focus the magnetic field, thereby directing it toward and around the solder pads. By directing the magnetic field emanating from the induction coil specifically toward the solder pads, the magnetic flux concentrator can ensure that current is precisely directed in these areas. This targeted induction can allow for controlled heating, which can be fine-tuned to melt only the solder paste without increasing the temperature of other areas or components on the PCB. This selective heating can be a significant advantage because 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 over a wide frequency spectrum, ranging from a few kHz to approximately 100 MHz. In these scenarios, the power supply can adaptively apply AC current at a variable frequency. For example, to solder an electronic component in a shorter time, the power supply can generate AC current at a higher frequency. Conversely, if the electronic component is heat-sensitive, 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, the pin size of the electrical component, the induction coil size, and the power specified for the soldering process. In these examples, the power supply can include any suitable power circuit topology for supplying this AC current at the desired frequency range.

[0059] The reflow induction coil can have various shapes and / or numbers of windings. The shape can be determined based on the size and / or shape of the soldering area. Furthermore, a power source can supply power to one or more induction coils. This allows multiple electrical components to be soldered at once.

[0060] Induction reflow can be used to solder components to PCBs in a variety of applications. For example, the induction reflow system described herein may be applicable to the assembly of PCBs used in wireless chargers. Specifically, these chargers can be designed to wirelessly charge battery-powered vehicles, including electric cars, bicycles, boats, and similar vehicles. Because wireless chargers can generate high power outputs that can reach up to 800 volts, the durability of the PCB assembly can be important for such applications. Therefore, it may be desirable for the PCB assembly to have robust electrical contacts that can withstand these powerful power levels. Furthermore, wireless chargers can have mechanical resilience, especially in scenarios where vehicles may drive over them. The induction reflow system and associated PCB assembly process disclosed herein can form such durable electrical contacts. This process leverages the benefits of induction reflow to ensure that the assembled PCB is suitable for use in these demanding wireless charging applications.

[0061] Although aspects of the present disclosure are described with reference to example components, interactions, and routines, those skilled in the art will understand 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 batteries, may be considered general references and are not intended to provide additional meaning or configuration to a particular battery. Furthermore, the examples and example configurations are not intended to be limiting and should not be construed to limit the scope of the present disclosure. Furthermore, the examples are intended to be illustrative and should not be construed as limiting.

[0062] 1A illustrates 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 120. The power supply 110 and the induction coil component 120 can be connected via an electrical connection 112.

[0063] 1A, the induction coil assembly 120 may include an induction coil 122 and a cooling pad 124. As shown in FIG. 1A, the induction coil 122 may have two input terminals 122A and 122B. Each of these two input terminals 122A and 122B may be connected to a corresponding output terminal of the power source 110 via an electrical connection 112. For example, the terminal 122A may be connected to the positive output terminal of the power source 110, and the terminal 122B may be connected to the ground terminal of the power source 110. In another example, the terminal 122B may be connected to the positive output terminal of the power source 110, and the terminal 122A may be connected to the ground terminal of the power source 110.

[0064] In some embodiments, an AC current can be applied between terminals 122A and 122B. An AC current can be passed through induction coil 122, causing induction coil 122 to generate a magnetic field. For example, a magnetic field in the shape of a circular magnetic flux can be generated around induction coil 122. In some examples, cooling pad 124 can surround terminals 122A and 122B of induction coil 122. Alternatively, in embodiments that do not include a cooling pad 124 or other cooling device, induction coil 122 can be air-cooled. In some embodiments, cooling pad 124 can be a liquid-cooled pipe. For example, such a liquid-cooled pipe can be connected to an external liquid-cooling device (not shown in FIG. 1A ). The liquid-cooling device can have a reservoir for storing liquid and can be configured to supply liquid to cooling pad 124.

[0065] The power supply 110 can generate AC current for induction reflow. In some embodiments, the power supply 110 can include a DC-to-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 battery pack, a power line provided by a utility company, a real-time power source (e.g., a solar or wind energy source), a stored energy cell, 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 relatively high-frequency AC current with a resonant frequency in the MHz range. For example, the frequency range can be at least 1 MHz, such as 2 MHz to 10 MHz, 2 MHz to 40 MHz, the high frequency (HF) range, 3 MHz to 30 MHz, or the very high frequency (VHF) range of 30 MHz to 300 MHz. To generate such high-frequency AC current, the present application provides various power inverter topologies, such as those described in FIGS. 2A-2C.

[0066] 1B illustrates an example of an induction reflow system 150 according to some embodiments. More specifically, the induction reflow system 150 may include a power supply 110 and multiple induction coil components 120-1 and 120-2. Any suitable number of induction coil components 120-1 and 120-2 may be connected to a single power supply 110. The multiple induction coil components 120-1 and 120-2 may simultaneously form solder joints during induction reflow. The power supply 110 may be connected to each of the induction coil components 120-1 and 120-2 via electrical connections 112-1 and 112-2. The power supply 110 may provide AC power to each of the multiple induction coil components 120-1 and 120-2. Each of the induction coil components 120-1 and 120-2 may include an induction coil 122-1 or 122-2, terminals 122A-1 and 122B-1 or 122A-2 and 122B-2, and a cooling pad 124-1 or 124-2, respectively.

[0067] Each of the induction coil components 120-1 and 120-2 can simultaneously form one or more solder joints connected to respective electronic components (e.g., one or more through-hole components, one or more surface-mount components, etc.) disposed on the PCB. The induction coil component 120-1 can form a single solder joint or multiple solder joints, and the induction coil component 120-2 can form a single solder joint or multiple solder joints. In certain applications, the induction coils 120-1 and 120-2 can have similar shapes and / or sizes. In some other applications, the induction coils 120-1 and 120-2 can have different shapes and / or sizes. Additionally, the number of induction coil components can be determined based on the particular application, and the present disclosure does not limit the number of induction coil components that can be connected to the power source 110.

[0068] 2A-2C illustrate exemplary inverter circuit topologies of the power supply 110 in an induction reflow system according to some embodiments. In some embodiments, these inverter circuit topologies can generate high-frequency AC current. The high-frequency AC current can exceed 1 MHz. The high-frequency AC current can have a frequency in the range of 1 MHz to 100 MHz, e.g., 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 the range of 30 MHz to 300 MHz. Higher frequency AC currents can increase eddy currents in copper pad losses, which can be proportional to the square of the current times the resistance. For example, as the frequency of the AC current increases (for the same magnitude of AC current), copper pad losses can be higher, which can be proportional to the resistance times the square of the current. Therefore, resistance can be higher at higher frequencies due to skin depth, and therefore losses in the form of heat can be higher at higher frequencies. Each power supply 110 shown in Figures 2A-2C can be configured with a different circuit topology 210, 220, or 230 capable of generating high frequency AC current.

[0069] 2A illustrates an exemplary induction reflow system 200A. As shown 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 to the induction coil 122 via terminals 122A and 122B.

[0070] 2A , a DC current can be generated from energy source 202 and inverted to an AC current using switches 212 and 214. These switches 212 and 214 can be field-effect transistors (FETs), such as metal-oxide semiconductor field-effect transistors (MOSFETs). In various embodiments, an AC current can be generated by controlling the switching sequence of each switch 212 and 214. In these embodiments, the frequency of the generated AC current can be related to the sequence applied to each of switches 212 and 214. For example, a faster switching speed (e.g., determined based on the sequence applied to switches 212 and 214) can increase the frequency of the AC current supplied to induction coil 122.

[0071] 2B illustrates an example of an induction reflow system 200B. As shown 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 shown in FIG. 2B , the DC current provided by energy source 202 can be inverted to AC current using switch 222. The class E topology also includes a resonant circuit. Switch 222 can be a FET, such as a MOSFET. In various embodiments, AC current can be generated by controlling the switching sequence of switch 222. In these embodiments, the frequency of the generated AC current can be related to the sequence applied to switch 222. In some embodiments, the class E topology included in inverter 220B can be configured to generate AC current having a frequency in the kilohertz to VHF frequency range, depending on the selection of power devices and the values ​​of the inductors and capacitors. For example, for an operating frequency of 10 MHz, inductor 122 can have an inductance in the range of several hundred nH, and capacitor 228A can have a capacitance in the range of several hundred pF.

[0073] 2C illustrates an example of an induction reflow system 200C. As shown in FIG. 2C, an inverter 230 having a Φ2 class topology can be included in the power supply 110 to generate AC current at a 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] 2C , inverter 230 can include a switch 232 and a resonant tank 236. In various embodiments, an AC current can be generated by controlling the switching sequence of switch 232. Additionally, resonant tank 236 can be configured to remove second harmonics in the voltage waveform, thereby reducing voltage stress on a switching device (e.g., switch 232). For example, resonant tank 236 can adjust harmonics in the voltage waveform generated at the output of switch 232 (e.g., drain terminal 232A of a MOSFET) to reduce output voltage stress on switch 232.

[0075] FIG. 3 illustrates an exemplary induction reflow system for performing induction reflow on a PCB assembly 300 according to one embodiment. As shown in FIG. 3 , PCB 310 can include one or more solder pads. In some embodiments, the solder pads can be through-hole pads. In some other examples, the solder pads can be surface-mount pads that can provide electrical contacts on the PCB to which surface-mount components can be assembled. The solder pads can provide connection points to electrical components, such as through-hole components, surface-mount technology (SMT) components, integrated circuits, or any other suitable electronic components. For example, each through-hole 312 (e.g., using a solder pad within through-hole 312) can facilitate electrical connections across PCB 310, connecting its top and bottom surfaces. In certain examples, electrical components are attached to PCB 310 by inserting their terminals into through-holes 312. The placement of these terminals can be on both sides of PCB 310, such as the top or bottom, depending on design specifications. To secure the terminals of the through-hole components to the PCB 310, solder paste is applied to the opposite side, and the solder paste flows into and through the through-holes 312 during the soldering process using an induction reflow system. If solder pads are applied to surface-mount components, the solder paste can be applied to the same side of the PCB as the surface-mount components. As shown in FIG. 3 , the PCB 310 can include multiple through-holes 312 and through-hole pins 314. The number and locations of this large number of through-holes 312 and through-hole pins 314 can be determined based on the PCB 310 layout designed for a particular application. Any suitable number and locations of the through-holes 312 and through-hole pins 314 can be implemented.

[0076] In various embodiments, the through-hole pins 314 may be soldered into the through-holes 312 by using an induction reflow system as disclosed herein. The through-hole pins 314 may establish electrical contact within the PCB 310. The through-hole pins 314 may function as electrical contacts on the PCB 310. For example, during assembly of an electrical component onto the PCB, the electrical contact terminals of the component are aligned and connected with corresponding through-hole pins 314 according to a predetermined layout.

[0077] In some embodiments, the through-hole pins 314 may be soldered into the through-holes 312 by utilizing an induction reflow system. In these implementations, the through-hole pins 314 may first be inserted into the through-holes 312. Subsequently, solder paste (not shown in FIG. 3 ) may be applied underneath the solder pads 318. A magnetic flux concentrator 320 may be positioned above the solder pads 318. The magnetic flux concentrator 320 may focus the magnetic field generated by the induction coil 122 onto the solder pads 318. Additionally, the magnetic flux concentrator 320 may include a central hole 322 to facilitate this process.

[0078] As shown in Figure 3, induction coil 122 can generate a magnetic field. This magnetic field can be generated by an AC current flowing through induction coil 122. For example, the current can enter through terminal 122A, travel through the coil, and exit through terminal 122B. Alternatively, the AC current can flow through terminal 122B, pass through induction coil 122, and exit through terminal 122C. This does not limit the direction of the AC current, and the direction of flow can be determined based on the particular application.

[0079] An AC current flowing through induction coil 122 can induce a magnetic field with circular magnetic flux lines perpendicular to the plane of solder pad 318. Solder pad 318 is made of a conductive material and interacts with this changing magnetic field. The fluctuating magnetic flux generates eddy currents on the surface of solder pad 318. These eddy currents generate heat on the surface of solder pad 318, which causes the solder paste disposed underneath solder pad 318 to melt and flow into through hole 312, thereby securing through-hole pin 314 within through hole 312.

[0080] The strength of the eddy currents induced in the solder pad 318 may be related to the frequency of the AC current passing through the induction coil 122. Specifically, the strength of eddy current losses increases with frequency, which should cause different rates of temperature rise. Therefore, the reflow temperature profile on the solder pad 318 can be controlled by changing the 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 adjusted. This control over temperature can be beneficial for achieving desired soldering results without damaging any components or materials involved in the process. In some cases, the cooling pad 124 can dissipate heat generated at the terminals 122A and 122B. This allows the AC current to continue to be supplied to the induction coil 122 without affecting the heat of the terminals 122A and 122B.

[0081] 4 illustrates an example cross-sectional view of a PCB assembly 300 during induction reflow. As shown in FIG. 4, the PCB 310 can incorporate through-holes 312 extending from the top surface to the bottom surface of the PCB 310. Through-hole pins 314 can be inserted into the through-holes 312. Solder paste 402 can be applied to the tops of the through-holes 312. In various examples, the solder paste 402 can melt and flow into the spaces between the through-holes 312 and the through-hole pins 314, thereby securing the through-hole pins 314 within the through-holes 312.

[0082] As further shown in FIG. 4 , solder pads 318 can be disposed on the PCB 310. Solder paste 402 can be applied on the solder pads 318. In some cases, the solder pads 318 can extend to opposite sides of the PCB 310 through through holes 312. For example, as shown in FIG. 4 , the solder pads 318 can be disposed on the top side 310A and bottom side 310B of the PCB by passing through through holes 312. The solder paste 402 can be applied to the bottom side 310B, such as underneath the solder pads 318 disposed on the bottom side 310B. In some embodiments, the solder paste 402 melts when heat is applied to the solder paste 402. A magnetic flux concentrator 320 can be disposed around the solder pads 318 (e.g., on the top side 310A of the PCB 310). In some implementations, this magnetic flux concentrator 320 can have a central hole 322 (as shown in FIG. 3 ) that allows the solder pads 318 located on the top surface 310A to be directly exposed to the magnetic field 410. By utilizing the magnetic flux concentrator 320, the magnetic field 410 can be focused onto the solder pads 318. This targeted magnetic field direction can reduce or eliminate overheating and / or damage to other components on the PCB 310.

[0083] Further, as shown in FIG. 4, AC current from power supply 110 can flow through induction coil 122 via terminal 122A. As described with respect to FIG. 4, this AC current can generate a magnetic field 410 around induction coil 122. This magnetic field can induce eddy currents on the surface of solder pad 318. The resulting eddy currents can increase the temperature of solder pad 318. This allows the heat generated in solder pad 318 to melt solder paste 402, causing it to flow and fill the gap between through-hole pin 314 and through-hole 312, completing the soldering process.

[0084] 5 shows an example of a PCB assembly 500 used for induction reflow using an induction reflow system including an induction coil having a solenoid shape. As shown, AC current from power supply 110 (e.g., as shown in FIG. 4) can flow from terminal 122A through solenoid-shaped induction coil 522 and exit via terminal 122B. In this configuration, solenoid-shaped induction coil 522 can generate a magnetic field 510 that is oriented perpendicular to both solder pads 318 and magnetic flux concentrator 320.

[0085] The top surface of solder pad 318 can be exposed through hole 322 in magnetic flux concentrator 320 (as shown in FIG. 3). As a result, magnetic field 510 can induce eddy currents in solder pad 318. These eddy currents can generate sufficient heat to melt solder paste 402 (as shown in FIG. 4) located on top of solder pad 318. Upon melting, solder paste 402 flows into and fills the space between through-hole pin 314 and through-hole 312, thereby forming a secure solder joint.

[0086] FIG. 6A illustrates an example of a PCB assembly 600A in which an induction reflow system can simultaneously solder multiple through-hole pins 314. As shown in FIG. 6A, a PCB 310 can include multiple solder joints 630, each of which can include a through-hole pin 314. An induction coil 622 can have a solenoid shape and surround the through-hole pins 314. While the solder joints 630 are shown as through-hole pin types, the solder joints 630 can also be joints for soldering surface-mounted components. This application does not limit the type of solder joints 630.

[0087] In some implementations, AC current from power supply 110 (e.g., as shown in FIG. 4 ) is conducted to solenoid-shaped induction coil 622 through terminal 122A and exits through terminal 122B. Alternatively, the current can enter through terminal 122B, cross solenoid-shaped induction coil 622, and exit through terminal 122A. This AC current can generate a magnetic field around induction coil 622. The magnetic field then induces eddy currents on the surface of solder pad 318.

[0088] Thus, the magnetic field generated by a single flow of AC current through the induction coil 622 can effectively induce sufficient heat across the solder pads 318 associated with multiple through-hole pins 314 to melt the solder and facilitate the soldering process for multiple pins simultaneously.

[0089] FIG. 6B illustrates an example of a PCB assembly 600B in which an induction reflow system can form multiple solder joints, according to one embodiment. As shown in FIG. 6B, a PCB 310 can include multiple solder joints. As shown in FIG. 6B, an induction coil 622 can simultaneously form solder joints located inside the illustrated induction coil 622. For example, as shown in FIG. 6B, the induction coil 622 can generate a magnetic field and induce eddy currents in the solder pads 318 within the induction coil 622. In some embodiments, multiple induction coils 122-1, 122-2, and 122-3 can simultaneously solder corresponding solder joints 630. In some examples, the induction coil 622, induction coils 122-1 through 122-3, and multi-turn induction coil 652 can simultaneously solder solder joints 630. In certain embodiments, these induction coils 622, 122-1 through 122-3, and 652 can receive AC power from a single power source. In some other embodiments, induction coils 622, 122-1 through 122-3, and 652 can receive AC power from more than one power source. In some examples, the power supplied to two or more of coils 622, 122-1 through 122-3, and 652 can be different. Furthermore, while solder joints 630 are shown as being soldered to through-hole pins 314, this illustration is provided by way of example. This is not intended to limit the type of solder joints 630, and each of coils 622, 122-1 through 122-3, and 652 can have any suitable electronic component soldered thereto. Furthermore, any suitable number of induction coils can be simultaneously powered for induction reflow.

[0090] 7A-7F illustrate various examples of induction coils according to embodiments disclosed herein. For example, the induction coil can be formed as a wide solenoid coil, as shown in FIG. 7A. The induction coil can be formed as a compact solenoid coil, as shown in FIG. 7B. The induction coil can also be formed as a spiral with multiple turns, as shown in FIG. 7C. The induction coil can include a single turn, as shown in FIGS. 7D-7F. Furthermore, the shape of the induction coil can be varied based on the area or shape of the solder pads, as shown in FIGS. 7D, 7E, and 7F. In certain applications, a single-turn coil has desirable performance at high current excitation.

[0091] Figure 8 shows an induction coil 122 forming solder joints for electronic components on a PCB 310. In Figure 8, the electronic components are through-hole components. Some or all of the soldering process for the PCB assembly can utilize an induction reflow process as described in this disclosure.

[0092] In some embodiments, the induction reflow process and system disclosed herein can be used in assembling PCB components for vehicle chargers and / or vehicle pads for wireless charging. Such PCB components 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 provide 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 provide 800 volts of direct current power from wirelessly received alternating current power.

[0093] Additional Embodiments In the foregoing specification, the present disclosure has been described with reference to particular embodiments. It will, however, be apparent that various modifications and changes can be made thereto without departing from the broader spirit and scope of the present disclosure. The specification and drawings are, therefore, to be regarded in an illustrative rather than a restrictive sense.

[0094] Indeed, while the present disclosure is in the context of particular embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and / or uses of the present invention and its equivalents. Moreover, while several variations of the embodiments have been shown and described in detail, other modifications that are within the scope of the present disclosure will be readily apparent to those skilled in the art based on this disclosure. It is also contemplated that various combinations or subcombinations of specific features and aspects of the embodiments may be made and still fall within the scope of the present disclosure. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another to form varying modes of the embodiments disclosed herein. The methods disclosed herein need not be performed in the order recited. Therefore, it is not intended that the scope of the present disclosure should be limited by the specific embodiments described above.

[0095] It will be understood that the systems and methods of the present disclosure each have several innovative aspects, no single one of which is solely responsible for 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 the present disclosure.

[0096] Furthermore, certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, while features may be described as working in a particular combination and initially claimed as such, one or more features from the claimed combination can, in some cases, be deleted from the combination, and the claimed combination may be referred to as a subcombination or a variation of a subcombination. No single feature or group of features is necessary or essential to every embodiment.

[0097] Conditional language used herein, such as "can," "could," "might," "may," "eg," and the like, unless otherwise specified or understood otherwise within the context of use, should be understood to generally convey that certain embodiments include certain features, elements, and / or steps, while other embodiments do not. Thus, such conditional language is not generally intended to imply that features, elements, and / or steps are somehow required by one or more embodiments, or that one or more embodiments necessarily include logic for determining whether those features, elements, and / or steps should be included in or performed in any particular embodiment, with or without author input or prompting. Terms such as "comprising," "having," and the like are synonymous and used in an inclusive, open-ended manner and do not exclude additional elements, features, acts, operations, etc. Furthermore, the term "or" is used in an inclusive sense (not an exclusive sense); for example, when used to connect a list of elements, the term "or" means one, some, or all of the elements in the list. Furthermore, the articles "a," "an," and "the," as used in this application and the appended claims, should be interpreted to mean "one or more" or "at least one" unless otherwise specified. Furthermore, while operations may be depicted in the figures in a particular order, it is recognized that such operations need not be performed in the particular order depicted, or in sequential order, or that all of the depicted operations need not be performed to achieve desirable results. Furthermore, the figures may generally depict additional exemplary processes in flowchart form. However, other operations not depicted may be incorporated into the generally depicted exemplary methods and processes. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the illustrated operations. Furthermore, operations may be rearranged or reordered in other embodiments. In certain situations, multitasking and parallel processing may be advantageous.Furthermore, the separation of various system components in the above embodiments should not be understood to require 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 in multiple software products. Moreover, other embodiments are within the scope of the following claims. In some cases, the activities recited in the claims may be performed in a different order and still achieve desirable results.

[0098] Furthermore, the methods and devices described herein may be susceptible to various modifications and alternative forms, specific examples of which are shown in the drawings and described in detail herein. However, it should be understood that the disclosure should not be limited to the particular forms or methods disclosed; on the contrary, the disclosure should encompass all modifications, equivalents, and alternatives falling within the spirit and scope of the various described embodiments and the appended claims. Furthermore, any particular feature, aspect, method, attribute, property, quality, attribute, element, etc., disclosed herein in connection with an embodiment or embodiment can be used with all other embodiments or embodiments described herein. The methods disclosed herein need not be performed in the order listed. Although the methods disclosed herein may include certain activities performed by a practitioner, the methods can also include, explicitly or implicitly, any third-party direction of those activities. Ranges disclosed herein also encompass any and all overlaps, subranges, and combinations thereof. Language such as "up to," "at least," "greater than," "less than," "between," and the like, includes the recited numbers. Numbers preceded by terms such as "about" or "approximately" are inclusive of the recited numbers and should be interpreted in accordance with the context (e.g., as precisely as reasonably possible under the circumstances, e.g., to within ±5%, ±10%, ±15%, etc.). Phrases preceded by terms such as "substantially" are inclusive of the recited terms and should be interpreted in accordance with the context (e.g., as much as reasonably possible under the circumstances). For example, "substantially constant" includes "constant." Unless otherwise specified, all measurements are made 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 encompass A, B, C, A and B, A and C, B and C, and A, B, and C. Connective language such as "at least one of X, Y, and Z," unless otherwise noted, is understood in the context in which it is generally used to convey that an item, term, etc., can be at least one of X, Y, or Z. Thus, such connective language is not generally intended to imply that a particular embodiment requires at least one of X, at least one of Y, and at least one of Z, for each occurrence. 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] Thus, the scope of the claims is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the present disclosure, principles, and novel features disclosed herein.

[0101] It should be understood that many variations and modifications can be made to the above-described embodiments, and that elements thereof are among other acceptable examples. All such modifications and variations are intended to be within the scope of the present disclosure. The above description details particular embodiments. However, it will be understood that no matter how detailed the foregoing may be, the systems and methods may be implemented in many ways. Also, as noted above, the use of a particular term when describing a particular feature or aspect of the systems and methods should not be construed as meaning that the term has been redefined herein to be limited to including any particular characteristic of the feature or aspect of the systems and methods with which the term is associated.

[0102] Many other variations beyond those described herein will be apparent from this disclosure. For example, depending on the embodiment, the processor disclosed herein may perform various processing schemes based on moving object detection data received from the object detection sensors, as disclosed herein.

[0103] Motion detection may generally refer to the detection of living objects, such as humans and animals, that can move or change position.

[0104] The various illustrative logic blocks and modules described in connection with the embodiments disclosed herein may 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. The processor may be a microprocessor, but in alternative examples, the processor may be a controller, microcontroller, or state machine, combinations thereof, etc. The processor may include electrical circuitry configured to process computer-executable instructions. In another embodiment, the processor includes an FPGA or other programmable device that performs logical operations without processing computer-executable instructions. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in combination with a DSP core, or any other such configuration. While described herein primarily with reference to digital technology, a processor may also include primarily analog components. The computing environment may include any type of computer system, including, but not limited to, a computer system based on a computational engine within a microprocessor, mainframe computer, digital signal processor, portable computing device, device controller, or appliance, to name a few.

Claims

1. 1. A method for assembling one or more electrical components on a printed circuit board (PCB) using induction reflow, comprising: supplying AC power to a plurality of induction coils; simultaneously transmitting magnetic fields from the plurality of induction coils to a solder material on the PCB to form a plurality of solder joints on the PCB; A method comprising:

2. The method of claim 1 , wherein a single power source provides the AC power to the multiple 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. 5. The method of claim 4, wherein the frequency is in the range of 2 megahertz to 40 megahertz.

6. The method of claim 1 , wherein the magnetic field of a first induction coil of the plurality of induction coils is transmitted to the solder material through a magnetic 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 disposed 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. 10. The method of claim 1, wherein the electronic components on the PCB are included in a wireless charging pad configured to provide 400 volts DC power from wirelessly received AC power, and at least one of the solder joints is connected to the electronic components.

11. 1. A method for assembling one or more electrical components on a printed circuit board (PCB) using induction reflow, comprising: supplying AC power to an induction coil; transmitting a magnetic field from the induction coil to a solder material on the PCB to form a plurality of solder joints on the PCB; A method comprising:

12. 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 source provides AC power to the induction coil and the second induction coil.

14. 12. The method of claim 11, wherein the alternating current has a frequency of at least 1 megahertz.

15. 1. A method for assembling one or more electrical components on a printed circuit board (PCB) using induction reflow, comprising: supplying AC power to an induction coil, the AC power having a frequency greater than 1 megahertz; transferring a magnetic field from the induction coil to a solder material on the PCB to form a solder joint on the PCB; A method comprising:

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

17. 16. The method of claim 15, wherein the frequency is in the range of 2 megahertz to 10 megahertz.

18. 16. The method of claim 15, wherein the frequency is in the range of 2 megahertz to 40 megahertz.

19. 1. An induction reflow system comprising: a power source for generating an alternating current; a plurality of induction coils connected to the power supply and configured to apply a magnetic field to inductively reflow solder from a plurality of solder joints on a printed circuit board simultaneously; 1. An induction reflow system comprising:

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

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

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

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

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

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