Patent Description:
Magnetic devices are electronic components that convert electric energy and magnetic energy into each other according to the principle of electromagnetic induction to implement energy conversion and transmission. A plurality of magnetic devices are mounted on a PCB (Printed Circuit Board printed circuit board) to implement electrical connections of the plurality of magnetic devices, so that a current or a signal can be transferred among the magnetic devices. A PCB is a carrier of many electronic components in electronic products, and makes an order connection of the electronic components possible. The PCB has become a core part of modern electronic products. A pin of a magnetic device undertakes functions of through-current, fixing, and heat dissipation. A pin is made of a copper wire winding with soldering tin and is inserted onto a PCB. A through-current area of the existing copper pin is the same as that of the winding. The temperature resistance of materials for magnetic devices is <NUM> or above. The temperature resistance of PCBs is limited by board materials. The allowed temperature resistance of PCBs is lower than <NUM>. The temperature resistance of device materials is not fully utilized.

In practice, copper is expensive and heavy. An aluminum wire winding is gradually used to replace the copper wire winding, to reduce costs. A conductor on a surface of a PCB is copper. When a copper wire and an aluminum wire are connected, there is a specific potential difference between the copper wire and the aluminum wire due to different materials. If there is water vapor, electrolysis is caused to produce copper oxide and aluminum oxide. In this case, a contact surface is gradually corroded and oxidized, resulting in poor contact at the contact surface, increased contact resistance, and hot wires, and consequently causing accidents. Therefore, it is difficult to prevent a magnetic device with an aluminum wire from being oxidized when being soldered to a PCB.

In order to resolve the problem in soldering of an aluminum wire inductor and a PCB, in practice, one end of an aluminum wire and one end of a copper wire are soldered, and the other end of the copper wire is tin-coated and then soldered to a PCB. The introduction of copper-aluminum soldering requires protection on a plurality of soldering joints, resulting in cumbersome processes and high costs. In practice, an aluminum wire is ultrasonically coated with Sn-Zn solder, and then the aluminum wire is soldered to a PCB. However, a soldering joint cracks when the temperature is above <NUM> and the air humidity is above <NUM> % for more than <NUM> hours.

<CIT> discloses an electronic apparatus with a circuit board including a through hole into which a wire is inserted, the wire being an external terminal of a first electronic component such as a resistor, capacitor or inductor. The document describes that the wire comprises a metal wire made of iron or copper over which a Sn-Cu alloy layer and a plating metal layer made of nickel or copper are formed, and that the Sn-Cu alloy layer is formed over the metal wire via the plating metal layer.

<CIT> discloses a plug-in type integrally formed inductor, comprising a coil and a magnetic main body wrapping the outer side of the coil. A first welding pin and a second welding pin which extend downwards are arranged at the two ends of the coil respectively, a plurality of bosses are arranged at the bottom of the magnetic main body, and a plurality of heat dissipation grooves are formed between the bosses.

<CIT> discloses an aluminum wire inductor which can be easily welded on a circuit board through common soldering tin in a common welding manner. The inductor is welded on the circuit board through soldering tin and comprises an iron core wound by an enameled wire, the enameled wire comprises a conducting wire and an insulating layer, the conducting wire in the enameled wire is an aluminum wire, and a soldering layer is arranged at the connecting end of the aluminum wire.

<CIT> discloses an electric reactor comprising multiple iron core columns, coils, upper iron yokes and lower iron yokes, wherein the coils, the upper iron yokes and the lower iron yokes sleeve the iron core columns, the electric reactor further comprising an insulating fixing frame, the insulating fixing frame comprises a back plate, a first supporting plate and a second supporting plate, the back plate comprises a first surface and a second surface which are opposite, the first supporting plate and the second supporting plate are perpendicularly connected with and parallel to the first surface separately, the iron core columns are arranged between the first supporting plate and the second supporting plate side by side, the upper iron yokes are arranged on the surface, back onto the second supporting plate, of the first supporting plate, the lower iron yokes are arranged on the surface, back onto the first supporting plate, of the second supporting plate, the back plate is further provided with multiple lead holes, the coils comprise lead terminals, and the lead terminals run through the lead holes and are located outside the second surface.

<CIT> discloses a common mode choke coil comprising: a holder including side walls which have wire guide strips respectively formed at their sides and which have vertical guide grooves and horizontal flange stoppers both formed at their inner side surfaces; a coil assembly with edgewise windings of a rectangular wire provided around a bobbin with flanges; and a core securing plate spring, wherein the coil assembly is fixedly set in a correct position inside the holder such that protrusions formed at the flanges are put through the guide grooves thereby fixedly holding the bobbin in place horizontally while the flanges are locked by the flange stoppers thereby fixedly holding the bobbin in place vertically, and wherein lead wires of the edgewise windings are bent at upper ends of the wire guide strips, and then extend along the wire guide strips.

To resolve the foregoing problems, embodiments of this application provide a magnetic device and a method for manufacturing the magnetic device.

According to a first aspect of the present invention, this application provides a magnetic device as defined in present claim <NUM>. The magnetic device includes a magnetic core, a base, a winding, and a plurality of pins. Parts of two ends of the winding that pass through the base are the pins. A first metal layer and a second metal layer are sequentially stacked on a part or all of a side surface of each pin. The first metal layer is coated on a part or all of the side surface of each pin. The second metal layer is coated on an outer side of the first metal layer. The two metal layers are coated on an outer surface of each pin, which increases a transverse section area of each pin, increases soldering strength between each pin and a circuit board, reduces heat generated from a contact point between each pin and the circuit board, and increases a through-current capability of each pin. In a possible implementation, not forming part of the present invention, the winding includes a copper wire, parts of two ends of the copper wire that pass through the base of the magnetic device are the pins, the first metal layer includes copper foil, and the second metal layer includes a tin layer or a tin alloy layer. When the winding includes the copper wire, the first metal layer also includes the copper foil. In this case, there is no potential difference between metals of a same type, thereby reducing soldering difficulty. In addition, a surface of a PCB is metal copper, so that there is also no potential difference in soldering of metals of a same type, thereby increasing mechanical strength of soldering the magnetic device to the PCB. The second metal layer includes the tin layer or the tin alloy layer. Tin has a low melting point and can be quickly solidified, which facilitates soldering of the magnetic device to the PCB.

In a possible implementation, not forming part of the present invention, the winding includes an aluminum wire, parts of two ends of the aluminum wire that pass through the base of the magnetic device are the pins, the first metal layer includes copper foil, and the second metal layer includes a tin layer or a tin alloy layer. The copper foil may be soldered to a surface of the pin by using an ultrasonic soldering process, so that the copper foil is coated on the surface of the pin, to facilitate soldering the pin to the PCB. The second metal layer includes the tin layer or the tin alloy layer. Tin has a low melting point and can be quickly solidified, which facilitates soldering of the magnetic device to the PCB.

In a possible implementation, according to the present invention, the winding includes an aluminum wire, the first metal layer includes copper-aluminum composite foil, and the second metal layer includes a tin layer or a tin alloy layer. The copper-aluminum composite foil includes two layers. A first layer of the copper-aluminum composite foil is an aluminum layer, and a second layer of the copper-aluminum composite foil is a copper layer. The aluminum layer of the copper-aluminum composite foil is in contact with the winding, and the copper layer of the copper-aluminum composite foil is in contact with the second metal layer, which can slow down the generation of a potential difference between copper and aluminum, thereby preventing accidents caused by poor contact.

In a possible implementation, a transverse section of the pin is of a U shape, a circular shape, or a rectangular shape. A longitudinal section of the pin is of a rectangular shape, a T shape, or a trapezoidal shape. By adopting the above shapes, a through-current area and volume of the pin can be increased. According to the formulas Q = I<NUM>*R*t (where Q is heat generated by the pin, I is a current value of the pin, R is a resistance value of the pin, and t is power-on time) and R = ρ*L/S (where ρ is resistivity of the pin, L is a length of the pin, and S is a cross-sectional area of the pin), it can be learned that the resistance R of the pin is inversely proportional to the cross-sectional area S of the pin. The first metal layer and the second metal layer are sequentially coated on the outer surface of the pin. In this case, the cross-sectional area S of the pin increases, the resistance R of the pin decreases, and the heat Q generated by the pin decreases. Therefore, the heat generated from the contact point between the pin and the circuit board is reduced. In addition, according to the specific heat capacity formula c = Q/(m*ΔT) (where c is specific heat capacity of the pin, Q is absorbed (or released) heat, m is mass of the pin, and ΔT is an amount of temperature change after heat absorption (or heat release)), when the specific heat capacity c of the pin is a fixed value, the mass m of the pin increases, the heat Q generated by the pin decreases, and ΔT decreases. Therefore, the temperature rise of the pins is reduced. In addition, the cross-sectional area S of the pin increases, resulting in an increase in a soldering area between the pin and the circuit board, thereby increasing mechanical strength of a connection between the pin and the circuit board. Moreover, the current flowing through the pin per unit time is increased, thereby enhancing a through-current capability of the pin.

According to a second aspect of the present invention, this application provides a method for manufacturing a magnetic device as defined in present claim <NUM>. The magnetic device includes a magnetic core, a base, a winding, and a plurality of pins. Parts of two ends of the winding that pass through the base are the pins. A first metal layer and a second metal layer are sequentially stacked on a part or all of a side surface of a pin. The method for manufacturing the magnetic device includes: winding the winding on a winding framework of the magnetic device; soldering the first metal layer to a part or all of the side surface of the pin; assembling the magnetic core and the base; and immersing the pin in tin, soldering the second metal layer to an outer side of the first metal layer, and removing a solder icicle. The manufacturing method simplifies a manufacturing process and procedure of the pin in the magnetic device. The magnetic device manufactured according to the method has a high through-current capability and high mechanical strength.

According to a third aspect of the present invention, this application provides an electronic device as defined in present claim <NUM>. The electronic device includes a circuit board and the magnetic device as described above. The magnetic device is mounted on the circuit board by using the pins. The magnetic device includes a magnetic core, a winding, and a plurality of pins. In an extension direction of a pin, a first metal layer and a second metal layer are sequentially stacked on a part or all of a side surface of the pin. The first metal layer is coated on a part or all of the side surface of the pin, and the first metal layer has low resistivity. The second metal layer is coated on an outer side of the first metal layer, and the second metal layer has a low melting point and can be quickly solidified, which facilitates soldering.

To make the objectives, technical solutions, and advantages of embodiments of this application clearer, the following describes embodiments of this application in detail with reference to the accompanying drawings. Terms used in implementations of this application are only used to explain specific embodiments of this application, but are not intended to limit this application. It is clear that the described embodiments are merely some rather than all of embodiments of this application. Implementations described in the following example embodiments do not represent all implementations consistent with this application. On the contrary, the implementations are merely examples of apparatuses and methods that are described in the appended claims in detail and that are consistent with some aspects of this application.

For ease of understanding, terms in embodiments of this application are first explained.

A magnetic device includes a coil and a soft magnetic material. After a current passes through, the coil generates a magnetic field, and the magnetic material converges magnetic field lines. The magnetic field disappears after powering off. Magnetic devices mainly include power transformers, signal transformers, inductors, and the like. However, due to different application scenarios, the devices have various structures and material forms. A magnetic device usually includes a winding and a magnetic core. A transformer usually includes more than two windings, and therefore includes more than four pins. An inductor is a component that can convert electrical energy into magnetic energy and store the magnetic energy, and usually includes one winding and more than two pins. Magnetic devices are connected by soldering pins of the magnetic devices on a circuit board.

In practice, a pin of a magnetic device is soldered on a PCB, and the pin is usually made of a copper wire winding or an aluminum wire winding. However, copper is expensive and heavy. An aluminum wire winding is gradually used to replace the copper wire winding, to reduce costs. A conductor on a surface of a PCB is copper. When a copper wire and an aluminum wire are connected, there is a specific potential difference between the copper wire and the aluminum wire due to different materials. If there is water vapor, electrolysis is caused to produce copper oxide and aluminum oxide. In this case, a contact surface is gradually corroded and oxidized, resulting in poor contact at the contact surface, increased contact resistance, and hot wires, and consequently causing accidents. In addition, as a PCB is increasingly widely used in high-power scenarios, it is critical to improve a through-current capability, mechanical strength, and reliability of the magnetic device for application of the magnetic device in high-power scenarios.

To resolve the foregoing problems, this application provides a magnetic device and a manufacturing method thereof, and an electronic device. The magnetic device in embodiments of this application has a simple manufacturing process, can be better soldered to a circuit board, has good heat conduction effect, and improves mechanical strength of fixing the magnetic device on the circuit board.

Refer to <FIG>. <FIG> is a schematic diagram of a structure of a magnetic device <NUM> according to an embodiment of this application. <FIG> is a bottom view of the magnetic device <NUM> according to an embodiment of this application. <FIG> is a top view of a pin <NUM> of the magnetic device <NUM> according to an embodiment of this application. An embodiment of this application provides a magnetic device <NUM>. The magnetic device <NUM> includes a magnetic core <NUM>, a winding <NUM>, and a plurality of pins <NUM>. Parts of two ends of the winding that pass through a base <NUM> are the pins <NUM>. A first metal layer <NUM> and a second metal layer <NUM> are sequentially stacked on a part or all of a side surface of a pin <NUM>. The first metal layer <NUM> is coated on a part or all of the side surface of the pin <NUM>. The second metal layer <NUM> is coated on an outer side of the first metal layer <NUM>. The first metal layer <NUM> has low resistivity. The second metal layer <NUM> has a low melting point and can be quickly solidified, which facilitates soldering.

A process of coating the first metal layer <NUM> on the side surface of the pin <NUM> is not specifically limited in this embodiment of this application. For example, the first metal layer <NUM> may be soldered on the surface of the pin <NUM> by using various processes such as cold pressure welding, resistance welding, or ultrasonic welding.

A process of coating the second metal layer <NUM> on the outer side of the first metal layer <NUM> is not specifically limited in this embodiment of this application. For example, by using an impregnation method, the first metal layer <NUM> may be immersed in a liquid phase of the second metal and taken out after a period of time elapses. In this case, the second metal layer <NUM> is solidified on the surface of the first metal layer <NUM>.

In a possible implementation, not forming part of the present invention, the winding <NUM> includes a copper wire, the first metal layer <NUM> on the surface of the pin <NUM> includes copper foil, and the second metal layer <NUM> includes a tin layer or a tin alloy layer. When the winding includes the copper wire, the first metal layer <NUM> also includes the copper foil. In this case, there is no potential difference between metals of a same type, thereby reducing soldering difficulty. In addition, a surface of a PCB is metal copper, so that there is also no potential difference in soldering of metals of a same type, thereby increasing mechanical strength of soldering the magnetic device <NUM> to the PCB. The second metal layer <NUM> includes a tin layer or a tin alloy layer. The second metal layer <NUM> has a low melting point and can be quickly solidified, which facilitates soldering of the magnetic device <NUM> to the PCB.

A specific material of the second metal layer <NUM> is not limited in this embodiment of this application. For example, the second metal layer <NUM> may be a tin layer or a tin alloy layer, and the tin alloy layer includes a tin-copper alloy, a tin-zinc alloy, a tin-silver alloy, or the like.

Usually, a coil of the magnetic device <NUM> is wound using a copper wire. Characterized by moderate costs, low resistivity, excellent tensile strength or elongation, and easy processing, the copper wire is widely used in the magnetic device <NUM>. In addition, the coil may alternatively be wound using an aluminum wire. In terms of mechanical properties of the wire, tensile strength or elongation of the aluminum wire is lower than that of the copper wire, which can meet requirements of a product winding on the mechanical properties, and make the winding of the coil easier and more convenient, thereby saving processing time. In terms of specific gravity of the wire, density of copper is <NUM> times that of aluminum, and therefore weight of the aluminum wire is one third of that of the copper wire with a same cross-sectional area and length, so the use of the aluminum wire can save costs and resources.

In a possible implementation, not forming part of the present invention, the winding <NUM> includes an aluminum wire, the first metal layer <NUM> includes copper foil, and the first metal layer <NUM> is soldered to the surface of the pin <NUM> by using an ultrasonic process. The use of the aluminum wire for the winding <NUM> reduces costs and simplifies a manufacturing process of the winding <NUM>. The second metal layer <NUM> includes a tin layer or a tin alloy layer. The second metal layer <NUM> has a low melting point and can be quickly solidified, which facilitates soldering of the magnetic device <NUM> to the PCB.

In a possible implementation, according to the present invention, the winding <NUM> includes an aluminum wire, the first metal layer <NUM> includes copper-aluminum composite foil, and the second metal layer <NUM> includes a tin layer or a tin alloy layer. When the winding <NUM> includes the aluminum wire, the first metal layer <NUM> is coated on the side surface of the pin <NUM>, and the first metal layer <NUM> includes the copper-aluminum composite foil. The copper-aluminum composite foil includes two layers. A first layer of the copper-aluminum composite foil is an aluminum layer, and a second layer of the copper-aluminum composite foil is a copper layer. The aluminum layer is in contact with the winding <NUM>, and the copper layer is in contact with the second metal layer, which can slow down the generation of a potential difference between copper and aluminum, thereby preventing accidents.

The second metal layer <NUM> may be a tin alloy, such as a tin-copper alloy, a tin-zinc alloy, or a tin-silver alloy. When the foregoing layers are specifically provided in the structures, thickness of the first metal layer <NUM> and thickness of the second metal layer <NUM> are not strictly limited, and may be adjusted according to an actual requirement. Specifically, when the following conditions are met, good effects can be achieved. For example, when the first metal layer <NUM> includes copper foil, the thickness is usually <NUM>-<NUM>. When the first metal layer <NUM> includes copper-aluminum composite foil, the thickness is usually <NUM>-<NUM>, where the copper layer is about <NUM>. When the second metal layer <NUM> includes a tin-copper alloy layer, the thickness of the second metal layer <NUM> is usually about <NUM>.

A section shape of the pin <NUM> is not specifically limited in this embodiment of this application. For example, <FIG> are top views of the pin <NUM>, and a transverse section of the pin <NUM> is of a U shape, a circular shape, or a rectangular shape. <FIG> are side views of the pin <NUM>, and a longitudinal section of the pin <NUM> is of a rectangular shape, a T shape, or a trapezoidal shape. By adopting the above shapes, a through-current area and volume of the pin <NUM> can be increased. According to the formulas Q = I<NUM>*R*t (where Q is heat generated by the pin <NUM>, I is a current value of the pin <NUM>, R is a resistance value of the pin <NUM>, and t is power-on time) and R = ρ*L/S (where ρ is resistivity of the pin <NUM>, L is a length of the pin <NUM>, and S is a cross-sectional area of the pin <NUM>), it can be learned that the resistance R of the pin <NUM> is inversely proportional to the cross-sectional area S of the pin <NUM>. The first metal layer <NUM> and the second metal layer <NUM> are sequentially coated on the outer surface of the pin <NUM>. In this case, the cross-sectional area S of the pin <NUM> increases, the resistance R of the pin <NUM> decreases, and the heat Q generated by the pin <NUM> decreases. Therefore, the heat generated from the contact point between the pin <NUM> and the circuit board is reduced. In addition, according to the specific heat capacity formula c = Q/(m*ΔT) (where c is specific heat capacity of the pin <NUM>, Q is absorbed (or released) heat, m is mass of the pin <NUM>, and ΔT is an amount of temperature change after heat absorption (or heat release)), when the specific heat capacity c of the pin <NUM> is a fixed value, the mass m increases, the heat Q generated by the pin <NUM> decreases, and ΔT decreases. Therefore, the temperature rise of the pins <NUM> is reduced. In addition, the cross-sectional area S of the pin <NUM> increases, resulting in an increase in a soldering area between the pin <NUM> and the circuit board, thereby increasing mechanical strength of a connection between the pin <NUM> and the circuit board. Moreover, the current flowing through the pin <NUM> per unit time is increased, thereby enhancing a through-current capability of the pin <NUM>.

In a possible implementation, the transverse section of the pin <NUM> is of a U shape, and the longitudinal section is of a rectangular shape. When the transverse section is of the U shape, the first metal layer <NUM> and the second metal layer <NUM> are coated on three side surfaces of the pin <NUM>, which saves materials of the first metal layer <NUM> and the second metal layer <NUM>, facilitates a processing procedure of the pin <NUM>, and increases a contact area between the pin <NUM> and the circuit board, thereby increasing soldering strength between the magnetic device <NUM> and the circuit board, reducing heat generated from a contact point between the pin <NUM> and the circuit board, and increasing a through-current area of the pin <NUM>. When the longitudinal section is of the rectangular shape, a heat dissipation area of the pin <NUM> is increased, thereby achieving good heat dissipation effect.

In a possible implementation, the transverse section of the pin <NUM> is of a U shape, and the longitudinal section is of a T shape. When the transverse section is of the U shape, the first metal layer <NUM> and the second metal layer <NUM> are coated on three side surfaces of the pin <NUM>, which saves materials of the first metal layer <NUM> and the second metal layer <NUM>, facilitates a processing procedure of the pin <NUM>, and increases a contact area between the pin <NUM> and the circuit board, thereby increasing soldering strength between the magnetic device <NUM> and the circuit board, reducing heat generated from a contact point between the pin <NUM> and the circuit board, and increasing a through-current area of the pin <NUM>. When the longitudinal section is of the T shape, a heat dissipation area of the pin <NUM> is increased, thereby achieving good heat dissipation effect.

In a possible implementation, the transverse section of the pin <NUM> is of a U shape, and the longitudinal section is of a trapezoidal shape. When the transverse section is of the U shape, the first metal layer <NUM> and the second metal layer <NUM> are coated on three side surfaces of the pin <NUM>, which saves materials of the first metal layer <NUM> and the second metal layer <NUM>, facilitates a processing procedure of the pin <NUM>, and increases a contact area between the pin <NUM> and the circuit board, thereby increasing soldering strength between the magnetic device <NUM> and the circuit board, reducing heat generated from a contact point between the pin <NUM> and the circuit board, and increasing a through-current area of the pin <NUM>. When the longitudinal section is of the trapezoidal shape, a heat dissipation area of the pin <NUM> is increased, thereby achieving good heat dissipation effect.

In a possible implementation, the transverse section of the pin <NUM> is of a circular shape, and the longitudinal section is of a rectangular shape. When the transverse section is of the circular shape, a contact area between the pin <NUM> and the circuit board is increased, thereby increasing soldering strength between the magnetic device <NUM> and the circuit board, reducing heat generated from a contact point between the pin <NUM> and the circuit board, and increasing a through-current area of the pin <NUM>. When the longitudinal section is of the rectangular shape, a heat dissipation area of the pin <NUM> is increased, thereby achieving good heat dissipation effect.

In a possible implementation, the transverse section of the pin <NUM> is of a circular shape, and the longitudinal section is of a T shape. When the transverse section is of the circular shape, a contact area between the pin <NUM> and the circuit board is increased, thereby increasing soldering strength between the magnetic device <NUM> and the circuit board, reducing heat generated from a contact point between the pin <NUM> and the circuit board, and increasing a through-current area of the pin <NUM>. When the longitudinal section is of the T shape, a heat dissipation area of the pin <NUM> is increased, thereby achieving good heat dissipation effect.

In a possible implementation, the transverse section of the pin <NUM> is of a circular shape, and the longitudinal section is of a trapezoidal shape. When the transverse section is of the circular shape, a contact area between the pin <NUM> and the circuit board is increased, thereby increasing soldering strength between the magnetic device <NUM> and the circuit board, reducing heat generated from a contact point between the pin <NUM> and the circuit board, and increasing a through-current area of the pin <NUM>. When the longitudinal section is of the trapezoidal shape, a heat dissipation area of the pin <NUM> is increased, thereby achieving good heat dissipation effect.

In a possible implementation, the transverse section of the pin <NUM> is of a rectangular shape, and the longitudinal section is of a rectangular shape. When the transverse section is of the rectangular shape, a contact area between the pin <NUM> and the circuit board is increased, thereby increasing soldering strength between the magnetic device <NUM> and the circuit board, reducing heat generated from a contact point between the pin <NUM> and the circuit board, and increasing a through-current area of the pin <NUM>. When the longitudinal section is of the rectangular shape, a heat dissipation area of the pin <NUM> is increased, thereby achieving good heat dissipation effect.

In a possible implementation, the transverse section of the pin <NUM> is of a rectangular shape, and the longitudinal section is of a T shape. When the transverse section is of the rectangular shape, a contact area between the pin <NUM> and the circuit board is increased, thereby increasing soldering strength between the magnetic device <NUM> and the circuit board, reducing heat generated from a contact point between the pin <NUM> and the circuit board, and increasing a through-current area of the pin <NUM>. When the longitudinal section is of the T shape, a heat dissipation area of the pin <NUM> is increased, thereby achieving good heat dissipation effect.

In a possible implementation, the transverse section of the pin <NUM> is of a rectangular shape, and the longitudinal section is of a trapezoidal shape. When the transverse section is of the rectangular shape, a contact area between the pin <NUM> and the circuit board is increased, thereby increasing soldering strength between the magnetic device <NUM> and the circuit board, reducing heat generated from a contact point between the pin <NUM> and the circuit board, and increasing a through-current area of the pin <NUM>. When the longitudinal section is of the trapezoidal shape, a heat dissipation area of the pin <NUM> is increased, thereby achieving good heat dissipation effect.

An embodiment of this application provides a method for manufacturing the magnetic device <NUM>. The magnetic device <NUM> includes a magnetic core <NUM>, a winding, and a plurality of pins <NUM>. Parts of two ends of the winding that pass through a base are the pins <NUM>. A first metal layer <NUM> and a second metal layer <NUM> are sequentially stacked on a part or all of a side surface of a pin <NUM>.

The manufacturing method includes: winding the winding on a winding framework of the magnetic device; soldering the first metal layer to a part or all of the side surface of the pin of the magnetic device; assembling the magnetic core and the base; and immersing the pin in tin, soldering the second metal layer to an outer side of the first metal layer, and removing a solder icicle.

For ease of understanding, the following describes in detail the method for manufacturing the magnetic device <NUM> in this embodiment of the present invention in a specific application scenario.

Step <NUM>: Wire winding: An aluminum wire is wound on a winding framework of the magnetic device <NUM>.

Step <NUM>: Soldering: An insulation layer of the pin <NUM> is removed by using a chemical corrosion method or a laser method, and the first metal layer <NUM> is soldered to the pin <NUM>, where the soldering process includes cold pressure welding, resistance welding, and ultrasonic welding. In this case, the first metal layer <NUM> is coated on a part or all of the side surface of the pin <NUM> of the magnetic device <NUM>.

Step <NUM>: Bottom plate assembling: The magnetic core <NUM> with the winding and the base <NUM> are assembled.

Step <NUM>: Immersion in tin: The pin <NUM> is immersed in tin to coat the second metal layer <NUM> on the outer side of the first metal layer <NUM>, and a solder icicle is removed.

An embodiment of this application provides an electronic device. The electronic device includes a circuit board and the magnetic device <NUM> as described above. The magnetic device <NUM> is mounted on the circuit board by using the pins <NUM>. The magnetic device <NUM> includes a magnetic core <NUM>, a winding, and a plurality of pins <NUM>. Parts of two ends of the winding that pass through a base are the pins <NUM>. A first metal layer <NUM> and a second metal layer <NUM> are sequentially stacked on a part or all of a side surface of a pin <NUM>. The first metal layer <NUM> is coated on a part or all of the side surface of the pin <NUM>, and the first metal layer <NUM> has low resistivity. The second metal layer <NUM> is coated on an outer side of the first metal layer <NUM>, and the second metal layer <NUM> has a low melting point and can be quickly solidified, which facilitates soldering.

It should be noted that a process of fixing the magnetic device <NUM> on the circuit board is not limited in this embodiment of this application. For example, the pin <NUM> of the magnetic device <NUM> may be fixed on the circuit board by using a process of wave soldering, laser welding, or reflow soldering.

Claim 1:
A magnetic device (<NUM>), comprising a magnetic core (<NUM>), a base (<NUM>), a winding (<NUM>), and a plurality of pins (<NUM>), wherein the winding (<NUM>) is arranged inside the magnetic core (<NUM>) and parts of two ends of the winding (<NUM>) that pass through the base (<NUM>) are the pins (<NUM>), and a first metal layer (<NUM>) and a second metal layer (<NUM>) are sequentially stacked on a part or all of a side surface of each pin (<NUM>) of the plurality of pins (<NUM>);
the first metal layer (<NUM>) is coated on a part or all of the side surface of each pin (<NUM>); and
the second metal layer (<NUM>) is coated on an outer side of the first metal layer (<NUM>), wherein the winding (<NUM>) comprises an aluminum wire, the first metal layer (<NUM>) comprises a copper-aluminum composite foil, and the second metal layer (<NUM>) comprises a tin layer or a tin alloy layer; and the copper-aluminum composite foil comprises two layers, a first layer of the copper-aluminum composite foil is an aluminum layer, a second layer of the copper-aluminum composite foil is a copper layer, the aluminum layer is in contact with the winding (<NUM>), and the copper layer is in contact with the second metal layer (<NUM>).