Inductive reflow for printed circuit board assemblies

Abstract

The invention relates to inductive reflow of a printed circuit board assembly. Aspects of the present disclosure relate to inductive reflow systems and related inductive reflow methods. In some embodiments, an inductive reflow system includes a power source and a plurality of inductive coils. Using an inductive reflow system, the solder may be inductively reflowed to form a solder joint on the printed circuit board. In some applications, the power source may apply an alternating current at a frequency of at least 1 megahertz.

Description

[0001] Cross-application in related fields

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 487,568, filed on February 28, 2023, entitled “Inductive Reflow of Printed Circuit Board Assemblies,” the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure generally relates to an electronic assembly system and method for assembling electronic components using induction reflow. Background Art

[0004] In the assembly of electronic components, various electronic components can be assembled on a printed circuit board (PCB). The assembly process may involve the use of solder paste. The solder paste can be precisely applied to designated pads on the surface of the PCB, 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 on the corresponding solder paste-coated pads. The electronic components are then firmly fixed to the PCB through a heating process, thereby melting the solder paste. This melting causes the solder to flow and form a strong bond between the component and the pads on the PCB. Reflow can be used in various manufacturing processes for assembling electronic components on PCBs. Improved reflow technology is generally highly anticipated. Summary of the Invention

[0005] The innovations described in the claims each contain multiple aspects, no single aspect of which alone determines its desirable properties. Without limiting the scope of the claims, some of the salient features of the disclosure will now be briefly described.

[0006] One aspect of the present disclosure is a method for assembling one or more electronic components on a printed circuit board (PCB). The method includes providing alternating current to a plurality of induction coils and simultaneously 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.

[0007] In one embodiment, a single power supply can provide AC power to multiple induction coils.

[0008] In one embodiment, a first induction coil of the plurality of induction coils may form at least two of the plurality of welding heads.

[0009] In one embodiment, the alternating current may have a frequency of at least 1 megahertz.

[0010] In one embodiment, the frequency of the alternating current may be in the range of 2 MHz to 40 MHz.

[0011] In one embodiment, the magnetic field of a first induction coil of the plurality of induction coils may be transmitted to the weld material through a flux concentrator.

[0012] In one embodiment, the induction coil may be a single-turn coil.

[0013] In one embodiment, a first soldering head of the plurality of soldering heads may be electrically connected to a surface mount component positioned on the PCB.

[0014] In one embodiment, the soldering tips may be electrically connected to surface mount components positioned on a PCB.

[0015] In one embodiment, a first solder joint of the plurality of solder joints may be electrically connected to the through-hole component.

[0016] In one embodiment, the electronic components on the PCB can be included in a wireless charging pad configured to provide 400 volts DC power via wirelessly received AC power. Additionally, at least one soldering head can be connected to the electronic components.

[0017] Another aspect of the present disclosure is a method for assembling one or more electronic components on a printed circuit board (PCB) using induction reflow. The method includes providing an alternating current 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.

[0018] In one embodiment, the method may further include transmitting a second magnetic field from a second induction coil to form at least one additional solder joint on the PCB while transmitting the magnetic field from the induction coil.

[0019] In one embodiment, a single power supply may provide alternating current to the induction coil and the second induction coil.

[0020] In one embodiment, the alternating current may have a frequency of at least 1 megahertz.

[0021] Another aspect of the present disclosure is a method for assembling one or more electronic components on a printed circuit board (PCB) using induction reflow. The method includes supplying an alternating current 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 frequency of the alternating current is greater than 1 MHz.

[0022] In one embodiment, transmitting a magnetic field from an induction coil may form a plurality of weld heads including the weld head.

[0023] In one embodiment, the frequency may be in the range of 2 MHz to 10 MHz. In one embodiment, the frequency may be in the range of 2 MHz to 40 MHz.

[0024] Another aspect of the present disclosure is an induction reflow system comprising 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 MHz. 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, forming at least one solder joint connected to at least one of the one or more electronic components.

[0025] In one embodiment, a magnetic field is transmitted from an induction coil to form a plurality of weld heads, the plurality of weld heads comprising the weld head.

[0026] In one embodiment, the alternating current may have a frequency in the range of 2 MHz to 10 MHz.

[0027] In one embodiment, the alternating current may have a frequency in the range of 2 MHz to 40 MHz.

[0028] Another aspect of the present disclosure is an induction reflow system comprising a power supply configured to generate alternating current and a plurality of induction coils configured to apply a magnetic field to inductively reflow solder, thereby simultaneously forming a plurality of solder joints on a printed circuit board.

[0029] In one embodiment, the induction reflow system may further include a flux concentrator to focus the magnetic field applied by the induction coil to form the weld joint.

[0030] In one embodiment, the alternating current may have a frequency of at least 1 megahertz.

[0031] In one embodiment, the frequency of the alternating current may be in the range of 2 MHz to 40 MHz.

[0032] In one embodiment, the power supply may include an inverter configured to generate alternating current from direct current.

[0033] In one embodiment, a first induction coil of the plurality of induction coils may have a single turn.

[0034] To summarize the present disclosure, certain aspects, advantages, and novel features of the innovations are described herein. It should be understood that not all of these advantages may be achieved according to any particular embodiment. Thus, the innovations may be embodied or implemented in a manner that achieves or optimizes one advantage or group of advantages taught herein without necessarily achieving other advantages that may be taught or suggested herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] These and other features, aspects, and advantages of the present disclosure will be described with reference to the accompanying drawings of certain embodiments, which are intended to illustrate the present disclosure rather than to limit the present disclosure. It should be understood that the accompanying drawings are incorporated into and constitute a part of this specification for the purpose of illustrating the concepts disclosed herein and may not be drawn to scale.

[0036] Figure 1A is a diagram of one example of an induction return system according to some embodiments.

[0037] Figure 1B is a diagram of one example of an induction return system with multiple induction coils, according to some embodiments.

[0038] Figures 2A to 2C Various examples of inverter circuit topologies according to some embodiments are shown.

[0039] Figure 3 An example of an inductive reflow system performing inductive reflow on a PCB assembly according to some embodiments is shown.

[0040] Figure 4 An example of a cross-sectional view of a PCB assembly during inductive reflow is shown in accordance with some embodiments.

[0041] Figure 5 An example of a PCB assembly with a solenoidal induction coil for inductive reflow is shown in accordance with some embodiments.

[0042] Figure 6A An example of a PCB assembly according to some embodiments is shown.

[0043] Figure 6B An example of a PCB assembly in which an inductive reflow system can form multiple joints is shown according to some embodiments.

[0044] 7A to 7F Various induction coils for inductive return are shown according to some embodiments.

[0045] Figure 8 An example of a PCB assembly in which solder joints are formed by induction reflow according to some embodiments is shown. DETAILED DESCRIPTION

[0046] The following detailed description of certain embodiments presents various descriptions of specific embodiments. However, the innovations described herein may be embodied in a variety of different ways, for example, as defined and encompassed by the claims. In this specification, reference is made to the accompanying drawings in which the same reference numerals and / or terms may represent identical or functionally similar elements. It should be understood that the elements shown in the drawings are not necessarily drawn to scale. Furthermore, it should be understood that certain embodiments may include more elements than shown in the drawings and / or a subset of the elements shown in the drawings. Furthermore, some embodiments may include any suitable combination of features from two or more of the drawings.

[0047] Various aspects of the present disclosure relate to an inductive return system and a method for manufacturing electrical contacts on the surface of a carrier board, such as a printed circuit board (PCB), by utilizing the inductive return system. Electrical contacts generally refer to terminals incorporated into a PCB that can provide or be included in a signal path between electronic components integrated into the PCB. Such electrical contacts can be applied by incorporating through-hole pins into each of a plurality of through-holes in the PCB. The inductive return system can include a power supply and an induction coil. The power supply can generate alternating current (AC current) in various frequency ranges, such as 1 megahertz (MHz) to 300 MHz. Such frequency ranges can include a high frequency (HF) range, such as between 3 MHz and 30 MHz and / or a very high frequency (VHF) range of 30 MHz to 300 MHz. When the induction coil receives the AC current from the power supply, it can generate a magnetic field. This magnetic field can induce eddy currents on the solder pads, thereby facilitating the assembly of the solder joint on the PCB.

[0048] In certain aspects of the present disclosure, induction reflow can form solder joints for through-hole components or surface-mount components. For soldering through-hole components, the assembly method may include positioning a pin (e.g., an electrical contact point on a PCB) within each of a plurality of through-holes on the PCB. For ease of illustration, one or more electronic components may be positioned on the top side of the PCB, with the contact points of each component aligned with corresponding through-holes. The term "contact point" generally refers to a terminal that provides electrical contact for an electronic component to electrically connect to (multiple) signal lines (such as copper signal lines) on the PCB. For example, a solder pad (such as a through-hole pad) may be positioned within a hole to facilitate this electrical connection by soldering a through-hole pin. In these examples, the through-hole pin may be inserted into a through-hole (a hole embedded through the top and bottom sides of the PCB), and the electronic component may be placed on the top side of the PCB, aligned with the through-hole pin. On the opposite side (bottom side) of the PCB, solder paste is applied to the pad within the through-hole. Subsequently, an induction coil may be positioned near the pad on the bottom side of the PCB, but without physical contact. Activating the induction coil with a power source generates a magnetic field, which in turn induces a current in the pad. This current can heat the solder paste, causing it to melt and penetrate the through-hole, thus forming a strong bond between the electronic component and the PCB. For example, solder paste can be positioned on top of a pad, and then the induction coil can apply a magnetic field to the pad. This magnetic field can induce eddy currents in the pad, which can generate heat from the pad, thus melting the solder paste.

[0049] In some embodiments, the assembly method disclosed in the present disclosure can be applied to assembling surface-mounted components onto a PCB. For example, solder can be applied to the PCB. In this example, the terminals (e.g., pins) of the surface-mounted components can be located on the solder. Eddy currents can be induced on the pins of the surface-mounted components, such as by placing an induction coil near the pins. In this example, the induced eddy currents can melt the solder paste. Although the present disclosure shows an example of induction reflow for assembling through-hole pins, any suitable induction reflow principles and advantages disclosed herein can be used to solder surface-mounted components onto a PCB.

[0050] The PCB layout can determine the specific location of each through hole.Any suitable principles and advantages disclosed herein can be applied to any suitable PCB layout.

[0051] In simple terms, inductive coupling between two conductors is a method for wirelessly transferring energy from one conductor to another. This technology uses magnetic fields to transfer power between the two conductors. For example, an inductive coil that generates a magnetic field within a specific range can transfer energy to another conductor in close proximity to the coil.

[0052] In PCB assembly manufacturing, there may be technical challenges associated with one or more passive components of varying sizes, through-hole components maintaining a reflow temperature profile, or the specialized reflow processes associated with large PCB assemblies.

[0053] Passive components of different sizes may have different thermal masses and require different times to heat to reflow temperature. Some PCB assemblies may only include surface mount technology (SMT) components. These components may include large SMT components (such as SMT film capacitors and / or inductors) with relatively large thermal mass and relatively slow heating and reflow, as well as smaller SMT components with much smaller thermal mass that can quickly reach reflow temperature. During reflow across the entire PCB assembly, components of different sizes may be heated unevenly. Achieving good soldering quality on large SMT components without overheating the small SMT components is difficult.

[0054] Through-hole components often require wave soldering because they cannot withstand the thermal profile of SMT reflow. 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 increase the cost and cycle time of PCB assembly manufacturing.

[0055] PCB assemblies that are larger than the capabilities of a typical SMT production line may require the use of a special reflow oven, which increases manufacturing costs. Examples of such large PCB assemblies include those suitable for induction reflow systems.

[0056] The present disclosure provides an equipment design and manufacturing process for a PCB assembly production line to utilize induction reflow to solder components on a PCB. Induction heating can be used to reflow solder paste applied to component pads (e.g., copper component pads) on a PCB, where the component pads are exposed to a relatively high-frequency magnetic field. For this process, a high-frequency power converter with an air core inductor can be used. These converters can be part of the induction reflow station equipment. The air core inductor can be placed relatively close to the target component pad to generate a local high-frequency magnetic field for induction reflow. The reflow process can be a process in which a loop of the air core inductor is used to selectively solder the target component, the loop being driven by a kilohertz (kHz), megahertz (MHz) frequency, or very high frequency (VHF) resonant circuit. Accordingly, the process can be converted into a process in which all selective locations are batch soldered at once. This is faster and less expensive than traditional reflow processes. The induction reflow soldering station can be located before or after a typical SMT soldering oven, replacing a wave soldering machine for selective soldering.

[0057] In some cases, most or all components on a PCB can be soldered using the same type of solder paste. Accordingly, both large and small SMT components can be soldered using the same solder material. The induction reflow disclosed herein can be applied to both sealed and non-sealed components.

[0058] Embodiments of the present disclosure provide a technical solution for assembling electronic components onto a PCB using an inductive coil. The inductive coil generates a magnetic field when it receives AC current from a power source. This magnetic field is positioned near the soldering pad and can induce current directly in the soldering pad itself and in the metal pins of the electronic components (e.g., surface mount components or through-hole components) soldered to the PCB. The heat generated by this induced current is sufficient to melt the solder paste, thereby allowing the electronic components to be attached without direct external heating. In various embodiments, the size of the coil can be adjusted according to the area of ​​the soldering pad. The inductive reflow method disclosed herein can form a solder joint faster than other reflow methods. The inductive reflow method disclosed herein can apply localized heating, thereby having less impact on other areas of the PCB (including areas that are susceptible to damage during reflow).

[0059] The present disclosure provides an electronic component assembly method utilizing an induction reflow process. When the process is initiated, the electronic component to be soldered is positioned on a PCB to which solder paste has been applied. During the reflow phase, one or more induction coils are placed near the solder paste. When a power supply begins generating AC current, the current is directed to the induction coils. Consequently, the coils generate a magnetic field oriented perpendicular to the solder pads, inducing eddy currents in the pads. These eddy currents cause a localized temperature increase, melting the solder paste and thereby securing the electronic component to the pads.

[0060] In some embodiments, the systems and methods described herein may incorporate a flux concentrator. A flux concentrator can focus the magnetic field. This can direct the magnetic field toward and around the solder pads. By directing the magnetic field emitted from the induction coil specifically toward the solder pads, the flux concentrator can ensure that current is precisely induced in these areas. This directional induction allows for controlled heating that can be finely tuned to melt only the solder paste without raising the temperature of other areas or components on the PCB. This selective heating has significant advantages because it can reduce and / or minimize the risk of thermal damage to adjacent components and areas during the soldering process.

[0061] In some examples, the power supply can generate a wide-spectrum AC current with a frequency range from a few kHz to approximately 100 MHz. In these cases, the power supply can adaptively apply a variable-frequency AC current. For example, to solder electronic components in a shorter time, the power supply can generate a higher-frequency AC current. 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 provided based on the solder pad area, the pin size of the electronic component, the size of the induction coil, and the specified power used for the soldering process. In these examples, the power supply can include any suitable power supply circuitry topology to provide this AC current within the required frequency range.

[0062] The inductor used for the reflow soldering process can have various shapes and / or numbers of turns. This shape can be determined by the size and / or shape of the soldering area. Furthermore, the power supply can power one or more inductors. This allows soldering multiple electronic components simultaneously.

[0063] Inductive reflow can be used to solder components to PCBs in a variety of applications. For example, the inductive reflow system described herein can be applied to the assembly of PCBs used in wireless chargers. Specifically, these chargers can be designed for wireless charging of battery-powered vehicles, including electric cars, bicycles, boats, and similar vehicles. Because wireless chargers can generate high power outputs, up to 800 volts, the durability of the PCB assembly is critical for such applications. Therefore, it is desirable for the PCB assembly to have robust electrical contacts that can withstand these high power levels. Additionally, wireless chargers can also be mechanically resilient, especially in situations where a vehicle could run over them. The inductive reflow system and its associated PCB assembly process disclosed herein enable the formation of such durable electrical contacts. The process leverages the advantages of inductive reflow to ensure that the assembled PCB is suitable for these demanding wireless charging applications.

[0064] Although aspects of the present disclosure will be described in conjunction with exemplary components, interactions, and routines, it will be understood by those skilled in the relevant art that one or more aspects of the present disclosure may be implemented according to various environments, system architectures, client computing device architectures, and the like. Similarly, references to specific devices (e.g., batteries) are to be considered general references and are not intended to provide additional meaning or configuration for a single battery. Furthermore, the illustrations and exemplary configurations are not intended to limit the scope of the present disclosure and should not be construed as limiting the scope of the present disclosure. Additionally, these examples are intended to be illustrative and should not be construed as limiting.

[0065] Figure 1AAn example of an induction backflow system 100 according to some embodiments is shown. More specifically, the induction backflow system 100 may include a power supply 110 and an induction coil assembly 120. The power supply 110 and the induction coil assembly 120 may be connected via an electrical connection 112.

[0066] like Figure 1A As shown, the induction coil assembly 120 may include an induction coil 122 and a cooling pad 124. Figure 1A As shown, the induction coil 122 may have two input terminals 122A and 122B. Both input terminals 122A and 122B may be connected to corresponding output terminals of the power supply 110 via the electrical connector 112. For example, terminal 122A may be connected to the positive output terminal of the power supply 110, and terminal 122B may be connected to the ground terminal of the power supply 110. In other examples, terminal 122B may be connected to the positive output terminal of the power supply 110, and terminal 122A may be connected to the ground terminal of the power supply 110.

[0067] In some embodiments, an AC current may be applied between terminals 122A and 122B. The AC current may pass through the induction coil 122, and the induction coil 122 may generate a magnetic field. For example, a circular flux-shaped magnetic field may be generated around the induction coil 122. In some examples, a cooling pad 124 may surround the terminals 122A and 122B of the induction coil 122. Alternatively, in embodiments that do not include a cooling pad 124 or other cooling device, the induction coil 122 may be air-cooled. In some embodiments, the cooling pad 124 may be a liquid cooling tube. For example, such a liquid cooling tube may be connected to an external liquid cooling device ( Figure 1A The liquid cooling device may have a reservoir for storing liquid and be configured to supply the liquid to the cooling pad 124.

[0068] The power supply 110 may generate an AC current for inductive return. In some embodiments, the power supply 110 may include a DC-AC current inverter ( Figure 1A In these embodiments, the power supply 110 may be powered by an energy source 202 (e.g., Figure 2A-2CThe power supply 110 may be configured to receive a DC current, such as from a battery or battery pack, a power line provided by a utility company, a real-time power source (e.g., solar cells or wind power), an energy storage battery, or any suitable combination thereof. The power supply 110 may provide an AC current having a frequency of at least 100 kilohertz (kHz). In some examples, the power supply 110 may generate a relatively high frequency AC current having a resonant frequency in the MHz range. For example, the frequency range may be at least 1 MHz, such as between 2 MHz and 10 MHz, between 2 MHz and 40 MHz, a high frequency (HF) range (between 3 MHz and 30 MHz), or a very high frequency (VHF) range of 30 MHz to 300 MHz. In order to generate such a high frequency AC current, the present application provides a method as follows: Figure 2A-2C Various power inverter topologies are shown.

[0069] Figure 1B An example of an induction reflow system 150 according to some embodiments is shown. More specifically, the induction reflow system 150 may include a power supply 110 and a plurality of induction coil assemblies 120-1 and 120-2. Any suitable number of induction coil assemblies 120-1 and 120-2 may be connected to a single power supply 110. The plurality of induction coil assemblies 120-1 and 120-2 may simultaneously form a weld joint during induction reflow. The power supply 110 and each of the induction coil assemblies 120-1 and 120-2 may be connected via electrical connections 112-1 and 112-2, respectively. The power supply 110 may provide AC power to each of the plurality of induction coil assemblies 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.

[0070] Each of the induction coil components 120-1 and 120-2 can simultaneously form one or more solder joints, which are respectively connected to corresponding electronic components (e.g., one or more through-hole components, one or more surface-mount components, etc.) positioned on the PCB. The induction coil component 120-1 can form one or more solder joints, and the induction coil component 120-2 can also form one or more solder joints. In some applications, the induction coil 120-1 and the induction coil 120-2 can have similar shapes and / or sizes. In other applications, the induction coil 120-1 and the induction coil 120-2 can have different shapes and / or sizes. In addition, the number of induction coil components can be determined according to the specific application, and the present disclosure does not limit the number of induction coil components that can be connected to the power supply 110.

[0071] Figure 2A-2CExample inverter circuit topologies for power supply 110 in an induction backflow system according to some embodiments are shown. In some embodiments, these inverter circuit system topologies can generate high-frequency AC current. The frequency of the high-frequency AC current can exceed 1 MHz. The frequency of the high-frequency AC current can range from 1 MHz to 100 MHz, for example, 1 MHz to 10 MHz, 2 MHz to 10 MHz, or 3 MHz to 30 MHz. In some applications, the frequency of the high-frequency AC current from power supply 110 can be very high, ranging from 30 MHz to 300 MHz. The higher the frequency of the AC current, the greater the eddy currents, and the losses in the copper pad are proportional to the square of the current multiplied by the resistance. For example, as the frequency of the AC current increases (at the same AC current amplitude), the losses in the copper pad also increase, which is proportional to the square of the resistance multiplied by the current. Therefore, due to the effect of skin depth, the resistance at high frequencies may be greater, resulting in higher losses in the form of heat at high frequencies. Figure 2A-2C Each power supply 110 shown may be configured with a different circuit topology 210 , 220 , or 230 that can generate a high frequency AC current.

[0072] Figure 2A An exemplary induction backflow system 200A is shown. Figure 2A As shown, power supply 110 may include inverter 210 having a class D topology. Inverter 210 may receive input DC power from energy source 202. The output of power supply 110 may be connected to induction coil 122 via terminals 122A and 122B.

[0073] like Figure 2A As shown, DC current can be generated from energy source 202 and converted to 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, controlling the switching sequence of each switch 212 and 214 can generate AC current. In these embodiments, the frequency of the generated AC current can be related to the order in which each switch 212 and 214 is applied. For example, if the switching speed (e.g., determined based on the order in which switches 212 and 214 are applied) is faster, the frequency of the AC current supplied to induction coil 122 can be higher.

[0074] Figure 2B An example of an induction backflow system 200B is shown. Figure 2B As shown, the power supply 110 may include an inverter 220 having a Class E topology. The inverter 220 may receive input DC power from the energy source 202 and provide AC current to the induction coil 122.

[0075] like Figure 2BAs shown, the DC current provided by the energy source 202 can be converted 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, the switching sequence of the control switch 222 can generate an 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 an AC current with a frequency range from kilohertz to VHF, depending on the selection of the power devices and the values ​​of the inductance and capacitance. For example, for an operating frequency of 10 MHz, the inductance of the inductor 122 can be in the range of several hundred nH, and the capacitance of the capacitor 228A can be in the range of several hundred pF.

[0076] Figure 2C An example of an induction backflow system 200C is shown. Figure 2C As shown, an inverter 230 having a Φ2-type topology may be included in the power supply 110 and generates AC current having a relatively high operating frequency. The inverter 230 may receive input DC power from the energy source 202 and output AC power to the induction coil 122.

[0077] like Figure 2C As shown, inverter 230 may include switch 232 and resonant tank 236. In various embodiments, controlling the switching sequence of switch 232 may generate an AC current. Furthermore, resonant tank 236 may be configured to eliminate second harmonics in a voltage waveform, thereby reducing voltage stress on a switching device (e.g., switch 232). For example, resonant tank 236 may tune harmonics of a 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.

[0078] Figure 3 An example inductive reflow system for inductively reflowing a PCB assembly 300 is shown in FIG. Figure 3As shown, PCB 310 may include one or more solder pads. In some embodiments, the solder pads may be through-hole pads. In other examples, the solder pads may be surface mount pads, which can provide electrical contact points on a PCB where surface-mounted 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 in through-hole 312) can facilitate electrical connections across PCB 310, connecting its top and bottom surfaces. In some cases, electrical components are mounted to PCB 310 by inserting their terminals into through-holes 312. These terminals can be located on either side of PCB 310, for example, on the top or bottom surface, depending on the design specifications. To secure the terminals of the through-hole components to PCB 310, solder paste is applied to the opposite side, and then, during the soldering process, an induction reflow system is used to cause the solder paste to flow into and through through-holes 312. If the solder pads are used for surface-mounted components, the solder paste can be applied to the same side of the PCB as the surface-mounted components. like Figure 3 As shown, PCB 310 may include a plurality of through-holes 312 and through-hole pins 314. The number and location of the plurality of through-holes 312 and through-hole pins 314 may be determined based on the layout of PCB 310 designed for a particular application. Any suitable number and location of through-holes 312 and through-hole pins 314 may be implemented.

[0079] In various embodiments, through-hole pins 314 can be soldered into through-holes 312 using the induction reflow system disclosed herein. Through-hole pins 314 can establish electrical contact points within PCB 310. The through-hole pins 314 can serve as electrical contact points on PCB 310. For example, when an electrical component is assembled onto a PCB, the electrical contact terminals of the component are aligned with and connected to corresponding through-hole pins 314 according to a predetermined layout.

[0080] In some embodiments, through-hole pins 314 may be soldered into through-holes 312 using an induction reflow system. In these embodiments, through-hole pins 314 may first be inserted into through-holes 312. Subsequently, solder paste may be applied under pads 318. Figure 3 ). Above the pad 318, a flux concentrator 320 may be positioned. The flux concentrator 320 may focus the magnetic field generated by the induction coil 122 onto the pad 318. Additionally, the flux concentrator 320 includes a central hole 322 to facilitate this process.

[0081] like Figure 3As shown, 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, flow through the coil, and then exit through terminal 122B. Alternatively, the AC current can enter through terminal 122B, flow through induction coil 122, and then exit through terminal 122C. The present invention is not limited to the direction of the AC current, and the flow direction can be determined based on the specific application.

[0082] The AC current flowing in the induction coil 122 induces a magnetic field with circular flux lines perpendicular to the plane of the pad 318. The pad 318, made of a conductive material, interacts with this changing magnetic field. The change in magnetic flux generates eddy currents on the surface of the pad 318. These eddy currents generate heat on the surface of the pad 318, which in turn causes the solder paste positioned below the pad 318 to melt and flow into the through-hole 312, thereby securing the through-hole pin 314 within the through-hole 312.

[0083] The intensity of the eddy current induced in the pad 318 may be related to the frequency of the AC current passing through the induction coil 122. Specifically, the intensity of the eddy current loss should increase with increasing frequency, resulting in different rates of temperature rise. Therefore, the reflow temperature profile on the pad 318 can be controlled by changing the AC current frequency and / or the 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 pad 318 can be adjusted. This control of temperature is conducive to achieving the desired welding effect without damaging any components or materials involved in the process. In some cases, the cooling pad 124 can dissipate the heat generated at the terminals 122A and 122B. Therefore, the AC current can be continuously supplied to the induction coil 122 without affecting the heat at the terminals 122A and 122B.

[0084] Figure 4 An example of a cross-sectional view of a PCB assembly 300 during induction reflow is shown. Figure 4 As shown, PCB 310 may include a through-hole 312 that extends from the top surface to the bottom surface of PCB 310. Through-hole pins 314 may be inserted through through-hole 312. Solder paste 402 may be applied to the top of through-hole 312. In various examples, solder paste 402 may melt and flow into the space between through-hole 312 and through-hole pin 314, thereby securing through-hole pin 314 within through-hole 312.

[0085] like Figure 4 As further shown, pads 318 may be located on PCB 310. Solder paste 402 may be applied to pads 318. In some cases, pads 318 may extend to the other side of PCB 310, passing through vias 312. For example, Figure 4As shown, pads 318 may be located on the top 310A and bottom 310B of the PCB via through-holes 312. Solder paste 402 may be applied to the bottom side 310B, such as below the pads 318 in the bottom side 310B. In some embodiments, when heat is applied to the solder paste 402, it melts. Surrounding the pads 318 (e.g., on the top side 310A of the PCB 310) may be a flux concentrator 320. In some embodiments, the flux concentrator 320 may have a central hole 322 (e.g., Figure 3 310A), thereby allowing the pads 318 located on the top portion 310A to be directly exposed to the magnetic field 410. The magnetic field 410 can be focused on the pads 318 using the flux concentrator 320. This targeted magnetic field induction can reduce or eliminate overheating and / or damage to other components on the PCB 310.

[0086] In addition, if Figure 4 As shown, AC current from power source 110 can flow to induction coil 122 via terminal 122A. Figure 4 As described above, the 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 pad 318. The eddy currents thus generated can increase the temperature of the pad 318. Therefore, the heat generated on the pad 318 can melt the solder paste 402, causing it to flow into and fill the gap between the through-hole pin 314 and the through-hole 312, thereby completing the soldering process.

[0087] Figure 5 An example of a PCB assembly 500 is shown, wherein an induction return system including an induction coil having a solenoid shape is used for induction return. As shown, a power supply 110 (e.g., Figure 4 AC current (as shown) can flow from terminal 122A through the solenoid-shaped induction coil 522 and out through terminal 122B. In this configuration, the solenoid-shaped induction coil 522 can generate a magnetic field 510 that is oriented perpendicular to the pad 318 and the flux concentrator 320.

[0088] The top surface of the pad 318 may be exposed through the hole 322 in the flux concentrator 320 (e.g., Figure 3 As shown in FIG. 3 ). Thus, the magnetic field 510 can induce eddy currents on the pad 318. These eddy currents can generate enough heat to melt the solder paste 402 located on top of the pad 318 (as shown in FIG. Figure 4 Once melted, solder paste 402 flows and fills the space between through-hole pin 314 and through-hole 312, thereby forming a strong solder joint.

[0089] Figure 6A An example of a PCB assembly 600A is shown in FIG. 1 , in which the induction reflow system can simultaneously solder multiple through-hole pins 314. Figure 6A As shown, PCB 310 may include a plurality of soldering heads 630, each of which may include a through-hole pin 314. Induction coil 622 may have a solenoid shape and surround these through-hole pins 314. Although soldering heads 630 are shown as through-hole pins, soldering heads 630 may also be connectors for soldering surface-mounted components. The present application does not limit the type of soldering heads 630.

[0090] In some embodiments, the power source 110 (e.g., Figure 4 AC current (as shown) is directed into the solenoid-shaped induction coil 622 via terminal 122A and out through terminal 122B. Alternatively, current may enter through terminal 122B, pass through the solenoid-shaped induction coil 622, and then out through terminal 122A. This AC current may generate a magnetic field around the induction coil 622. This magnetic field, in turn, induces eddy currents on the surface of the pad 318.

[0091] Thus, the magnetic field generated by the single AC current passing through the induction coil 622 can effectively induce sufficient heat on the solder pads 318 associated with the plurality of through-hole pins 314 to melt the solder and facilitate the soldering process of the plurality of pins simultaneously.

[0092] Figure 6B An example of a PCB assembly 600B is shown in which an inductive reflow system can form multiple joints according to one embodiment. Figure 6B As shown, PCB 310 may include a plurality of solder joints. Figure 6B As shown, the induction coil 622 can simultaneously form a weld joint located inside the induction coil 622. For example, Figure 6BAs shown, the induction coil 622 can generate a magnetic field and induce eddy currents on the solder pad 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 cases, the induction coil 622, the induction coils 122-1 to 122-3, and the multi-turn induction coil 652 can simultaneously solder the solder joint 630. In some embodiments, the induction coils 622, 122-1 to 122-3, and 652 can receive AC power from a single power source. In other embodiments, the induction coils 622, 122-1 to 122-3, and 652 can receive AC power from two or more power sources. In some examples, the power supplied to two or more of the coils 622, 122-1 to 122-3, and 652 can be different. Furthermore, while the solder joint 630 is shown as being soldered to the through-hole pin 314, this illustration is merely an example. The present invention is not limited to the type of soldering head 630, and each coil 622, 122-1 to 122-3 and 652 can solder any suitable electronic components. In addition, any number of induction coils can be powered simultaneously for induction reflow.

[0093] 7A to 7F Various examples of induction coils according to embodiments disclosed herein are shown. For example, the induction coil may be formed from a wide solenoid coil, such as Figure 7A The induction coil can be formed from a compact solenoid coil, such as Figure 7B The induction coil can also be formed by multiple turns of spiral wire, such as Figure 7C The induction coil may comprise a single turn, such as Figures 7D to 7F In addition, the shape of the induction coil can be modified according to the area or shape of the pad, as shown in Figure 7D 、 Figure 7E and Figure 7F In some applications, a single-turn coil provides ideal performance when excited by high current.

[0094] Figure 8 An induction coil 122 is shown forming a solder joint for an electronic component on a PCB 310. Figure 8 Part or all of the soldering process of the PCB assembly may utilize the induction reflow process described in the present disclosure.

[0095] In some embodiments, the inductive reflow process and system disclosed herein can be used to assemble a PCB component for a vehicle charger and / or 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 that is configured to supply 400 volts of DC current power via wirelessly received AC power. The electronic components on the PCB can be included in a wireless charging pad that is configured to supply 800 volts of DC current power via wirelessly received AC power.

[0096] Additional embodiments

[0097] In the foregoing description, the present disclosure has been described with reference to specific embodiments. However, it will be apparent that various modifications and variations may be made thereto without departing from the broader spirit and scope of the present disclosure. Accordingly, the description and drawings are to be regarded as illustrative rather than restrictive.

[0098] In fact, although the present disclosure is based on certain 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 their equivalents. In addition, although several variations of the embodiments have been shown and described in detail, it will be readily apparent to those skilled in the art based on the present disclosure that other modifications within the scope of the present disclosure are within the scope of the present 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 present disclosure. It will be understood that the various features and aspects of the disclosed embodiments may be combined or substituted with each other to form different modes of the embodiments disclosed herein. Any method disclosed herein does not have to be performed in the order described. Therefore, the scope of the present disclosure should not be limited by the specific embodiments described above.

[0099] It should be understood that the systems and methods of the present disclosure each have multiple innovative aspects, none of which is the sole cause or necessary condition for the desirable properties disclosed herein. The various features and processes described above can be used independently of one another or in combination in various ways. All possible combinations and subcombinations are intended to fall within the scope of this disclosure.

[0100] Certain features described in this specification in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable subcombination. Furthermore, although features may be described above as functioning in certain combinations, or even initially claimed as such, in certain circumstances one or more features in a claimed combination may be deleted from that combination, and a claimed combination may involve subcombinations or variations of subcombinations. No single feature or group of features is essential or indispensable for every embodiment.

[0101] It should also be understood that conditional language used herein, such as "can," "might," "perhaps," "could," "for example," etc., unless otherwise expressly stated or understood otherwise in context, is generally intended to express that certain embodiments include certain features, elements, and / or steps, while other embodiments do not include these features, elements, and / or steps. Therefore, such conditional language is generally not intended to imply that features, elements, and / or steps are in any way necessary for one or more embodiments, or that one or more embodiments necessarily include logic (whether input or prompted by the author) for determining whether these features, elements, and / or steps are included in a particular embodiment or whether they are performed in any particular embodiment. The terms "include," "comprise," "have," etc. are synonymous and are used in an inclusive, open-ended manner and do not exclude other elements, features, actions, operations, etc. In addition, the word "or" is inclusive (not exclusive), so, for example, when used to connect a series of elements, the word "or" means one, some, or all of the elements in the list. In addition, unless otherwise stated, the articles "a," "an," and "the" used in this application and the appended claims should be understood to mean "one or more" or "at least one." Similarly, while operations may be depicted in a particular order in the figures, it should be understood that these operations do not necessarily need to be performed in the particular order or sequential order shown, nor do all illustrated operations need to be performed to achieve the desired results. Furthermore, the figures may schematically depict one or more example processes in the form of flow charts. However, other operations not depicted may be incorporated into the schematically illustrated example methods and processes. For example, one or more additional operations may be performed before, after, concurrently with, or between any illustrated operations. Furthermore, in other embodiments, the operations may be rearranged or reordered. In certain circumstances, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system components in the above-described embodiments should not be construed as requiring such separation in all embodiments, and it should be understood that the described program components and systems may generally be integrated into a single software product or packaged into multiple software products. Furthermore, other embodiments are also within the scope of the following claims. In certain circumstances, the operations described in the claims may be performed in a different order and still achieve the desired results.

[0102] Furthermore, while the methods and apparatus described herein are susceptible to various modifications and alternative forms, specific examples thereof are shown in the drawings and described in detail herein. However, it should be understood that the present disclosure is not limited to the specific forms or methods disclosed, but rather, encompasses all modifications, equivalents, and alternatives falling within the spirit and scope of the various embodiments and the appended claims. Furthermore, any particular feature, aspect, method, characteristic, feature, quality, attribute, element, etc. disclosed herein with respect to an embodiment or example is applicable to all other embodiments or examples described herein. Any method disclosed herein does not need to be performed in the order described. The methods disclosed herein may include certain actions taken by the practitioner; however, these methods may also include instructions for those actions by any third party, whether express or implied. Ranges disclosed herein also encompass any and all overlapping portions, subranges, and combinations thereof. Phrases such as "up to," "at least," "greater than," "less than," "between," etc., are inclusive of the recited number. Numbers preceded by terms such as "about" or "approximately" are inclusive of the recited number and should be interpreted accordingly (e.g., as accurately as possible under the circumstances, e.g., ±5%, ±10%, ±15%, etc.). Phrases beginning with the term "substantially" include the referenced phrase and should be interpreted accordingly (e.g., as far as reasonable under the circumstances). For example, "substantially constant" includes "constant." Unless otherwise noted, all measurements are made under standard conditions, including temperature and pressure.

[0103] As used herein, phrases referring to a list of "at least one" items refer to any combination of these items, including individual items. For 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. Unless expressly stated otherwise, conjunctions such as phrases "at least one of X, Y, and Z" should be understood in conjunction with the context as being generally used to express that a certain item, term, etc. can be at least one of X, Y, or Z. Therefore, such conjunctions are generally not intended to imply that certain embodiments require that at least one of X, at least one of Y, and at least one of Z be present, respectively. The titles provided herein, if any, are for convenience only and do not necessarily affect the scope or meaning of the apparatus and methods disclosed herein.

[0104] Thus, 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.

[0105] Various changes and modifications may be made to the above-described embodiments, and the elements of these changes and modifications should be understood as other acceptable examples. All such modifications and variations are intended to be included within the scope of this disclosure. The foregoing description details certain embodiments. However, it should be understood that no matter how detailed the foregoing textual description is, these systems and methods can be practiced in a variety of ways. As described above, it should be noted that the use of a particular term in describing certain features or aspects of the systems and methods should not be understood to imply that the term is redefined herein to include only any specific characteristics of the features or aspects of the systems and methods associated with the term.

[0106] Numerous other variations besides those described herein will be apparent from this disclosure.For example, according to an embodiment, the processor disclosed herein may perform various processing schemes, as disclosed herein, based on moving object detection data received from an object detection sensor.

[0107] Moving object detection usually refers to liveness detection. For example, living objects such as humans and animals may have the ability to move or change position.

[0108] The various illustrative logical blocks and modules described in conjunction with the embodiments disclosed herein may be implemented or executed 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, to perform the functions described herein. The processor may be a microprocessor, or may also be a controller, a microcontroller or a state machine, or a combination thereof. The processor may include 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. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration. Although primarily described herein with respect to digital technology, the processor may also primarily include analog components. The computing environment may include any type of computer system, including but not limited to computer systems based on microprocessors, mainframe computers, digital signal processors, portable computing devices, device controllers, or computing engines within devices.

Claims

1. A method for assembling one or more electrical components on a printed circuit board (PCB) using induction reflow, the method comprising: providing alternating current to the plurality of induction coils; as well as The magnetic field is simultaneously transmitted from the plurality of induction coils to the soldering material on the PCB to form a plurality of solder joints on the PCB. 2 . The method of claim 1 , wherein a single power supply provides the alternating current 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 welding heads of the plurality of welding heads. The method of claim 1 , wherein the alternating current has a frequency of at least 1 MHz. The method of claim 4 , wherein the frequency is in the range of 2 MHz to 40 MHz. 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 weld material through a flux concentrator. The method of claim 1 , wherein the induction coil is a single-turn coil. 8 . The method of claim 1 , wherein a first soldering pin of the plurality of soldering pins 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 the electronic component on the PCB is included in a wireless charging pad configured to supply 400 volts DC power from wirelessly received AC power, and wherein at least one of the soldering heads is connected to the electronic component.

11. A method for assembling one or more electrical components on a printed circuit board (PCB) using induction reflow, the method comprising: Supplying alternating current to the induction coil; as well as A magnetic field is transmitted 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 transmitting a second magnetic field from a second induction coil to form at least one additional solder joint on the PCB simultaneously with transmitting the magnetic field from the induction coil.

13. The method of claim 12, wherein a single power supply provides alternating current 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 megahertz.

15. A method of assembling one or more electrical components on a printed circuit board (PCB) using induction reflow, the method comprising: providing an alternating current to the induction coil, the alternating current having a frequency greater than 1 MHz; as well as A magnetic field is transmitted 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 transmitting the magnetic field from the induction coil forms a plurality of weld heads, the plurality of weld heads including the weld head.

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

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

19. An induction reflow system comprising: a power supply configured to generate alternating current; as well as A plurality of induction coils are connected to the power supply, the plurality of induction coils being configured to apply a magnetic field to the induction reflow solder to simultaneously form a plurality of solder joints on the printed circuit board.

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

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

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

23. The inductive backflow system of claim 19, wherein the power supply comprises an inverter configured to generate the alternating current from a direct current.

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

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