Inductive device and DCDC converter manufactured by inductive device

Abstract

The utility model discloses an inductive device and a DCDC converter made of the inductive device, and the inductive device comprises a magnetizer which is provided with a wrapping post and an end part, and the end part is provided with a metal electrode; the conductive coil is wound on the wrapping post of the magnetizer, and the end part of the conductive coil is arranged on the metal electrode at the end part of the magnetizer and is in physical contact with the metal electrode; and the electric connecting piece is locally spheroid-shaped, is arranged above the end part of the conductive coil, is in physical contact with the end part of the conductive coil and the metal electrode of the magnetizer, and is electrically connected with the end part of the conductive coil and the metal electrode of the magnetizer. And the inductive device is electrically connected with an external circuit through the electric connecting piece. According to the inductive device disclosed by the embodiment of the utility model, the ellipsoid electric connecting piece is additionally arranged to be connected with an external circuit electrode, so that the weldability of the inductive device is improved.

Description

Technical Field

[0001] The utility model belongs to the field of micro-power DCDC converters of switching power supplies, and in particular relates to a small inductive device and a DCDC converter made of the same. Background Art

[0002] As a passive component, inductive devices are widely used in the micro-power switching power supply industry. With the development of miniaturization of electronic products, inductive devices are also constantly upgraded and iterated to reduce the size of the device itself. In order to reduce the size of the inductive device as much as possible, a winding type chip inductive device with a drum-shaped magnetic core as the main body has appeared on the market. The coil is wound on the magnetic core and directly welded to the electrode on the magnetic core. Then the entire inductive device is mounted on the PCB circuit board.

[0003] However, the current micro-power DCDC converter with a drum-shaped magnetic core as the main body of the winding type chip inductive device still has the following shortcomings:

[0004] The ends and tails of the conductive coil need to be welded to the metal electrodes of the magnetic core. The conductive coil itself contains an insulating film. During the welding process, the insulating film will remain on the metal electrode, reducing the contact area between the metal electrode of the magnetic core and the PCB pad, affecting the welding strength and reliability. In severe cases, a "cold weld" will be formed, and the metal electrode of the magnetic core will have no electrical connection with the PCB.

[0005] In order to solve the above-mentioned deficiencies, the industry has also proposed a solution, that is, before the end of the conductive coil is welded to the metal electrode of the magnetic core, the insulating film of the conductive coil is processed, and the method usually adopted is laser peeling, and then the wire head or wire tail after the insulating film is removed is welded to the metal electrode of the magnetic core by pulse spot welding or hot pressing welding; this method can solve the problem of solder resistance caused by the residual insulating film, but the energy of pulse welding or hot pressing welding is very large, and the tin layer on the surface of the metal electrode will be oxidized. The oxidized electrode will also cause poor welding with the PCB, such as solder resistance or cold welding or insufficient welding strength; at the same time, the enameled wire end is laser peeled in advance, and the peeling position and tolerance are difficult to control, which may easily lead to the peeling position and tolerance deviation, resulting in insufficient pressure resistance distance between the exposed end of the first coil conductor and the second coil, resulting in poor pressure resistance or reduced pressure resistance reliability.

[0006] In view of the above shortcomings, the industry also has an optimized solution, which is to add tin to the metal electrode by dipping it in a high-temperature tin furnace with a temperature greater than or equal to 400°C after the wire is welded at the end of the magnetic core, so as to remove the residual insulating paint and re-attach a new layer of solder to the metal electrode, thereby avoiding welding reliability problems caused by surface oxidation of the electrode; however, this solution also has hidden dangers. On the one hand, the magnetic core is a sintered body. Under the instantaneous high temperature of about 400°C when dipping it in a tin furnace, it is very likely to directly break or produce dark cracks, thereby affecting the magnetic conductivity of the magnetic core body; on the other hand The winding pole of this drum-shaped magnetic core is arranged in parallel with the metal electrode. The length of the patch inductive device is between 5.5mm and 6.3mm, the width is between 2.9mm and 3.5mm, and the height is ≤2.4mm. In the small-volume inductive device, the metal electrode and the wire coil are very close (the distance between them is only about 0.5mm). The tinning process is difficult to control and will not directly immerse the coil. The coil insulation film itself is not resistant to high temperature. It is very easy to cause the insulation film to be damaged or the life to be reduced when immersed in a high-temperature tin furnace of about 400℃, resulting in performance failure of the conductive coil. Utility Model Content

[0007] The utility model aims to overcome the defects in the prior art and provide an inductive device and a processing method thereof to improve the weldability problem of the metal electrode of the inductive device.

[0008] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0009] An inductive device comprises: a magnetic conductor, wherein the magnetic conductor is provided with a winding post and two ends, wherein the ends are provided with metal electrodes, wherein the winding post and the metal electrode are arranged in parallel between the two ends; a conductive coil, wherein the conductive coil is wound on the winding post of the magnetic conductor, wherein the ends of the conductive coil are arranged on the metal electrodes at the ends of the magnetic conductor and form physical contact with the metal electrodes; and an electrical connector, which is a solder body, which wraps around the ends of the conductive coil in a partial ellipsoidal shape or a film shape, and is arranged on the metal electrode of the magnetic conductor, so as to form physical contact with the ends of the conductive coil, the metal electrode of the magnetic conductor, and a circuit PCB board to form interconnected solder joints.

[0010] Preferably, the conductive coil further comprises a metal conductive wire core and an insulating film; the insulating film insulates the metal conductive wire core.

[0011] Preferably, the cross-section of the conductive core of the conductive coil is circular or square, and the insulating film of the conductive coil has a temperature resistance between 130°C and 240°C.

[0012] Preferably, the electrical connector comprises a solder body, the solder body of the electrical connector comprises tin, and the melting temperature of the solder body is ≤400°C.

[0013] The utility model also provides a DCDC converter, comprising the above-mentioned inductive device and a circuit PCB board, wherein the working power of the inductive device is ≤3W.

[0014] Preferably, the input voltage of the inductive device is between 2V-6V, the output voltage is between 2V-6V, and the input-output isolation withstand voltage is 2500VDC.

[0015] Preferably, the inductive device of the DCDC converter has a length between 5.5 mm and 6.3 mm, a width between 2.9 mm and 3.5 mm, and a height ≤ 2.4 mm.

[0016] Preferably, the packaging structure of the DCDC converter is a surface mount package, a SIP package or a DIP package.

[0017] The beneficial effects of the inductive device of the utility model and the DCDC converter made thereof are:

[0018] 1. The method of laser cleaning before soldering the interconnection solder joints, coupled with the use of a new ellipsoidal solder body, can avoid solder resistance or "false solder joints" caused by residual insulating film at the interconnection solder joints at the metal electrodes of the magnetic core; the surface of the new solder body is bright, which also improves the reliability of welding with the circuit PCB board pads;

[0019] 2. By adding electrical connectors to solder with the circuit PCB pads or external circuit electrodes, the solder body is supplemented based on this technology, and the temperature is lower than 400°C. When low-temperature tinning is used, the tin furnace temperature can be as low as 260-320°C, which will not affect the insulation performance and reliability of the coil body; there is no destructive effect on the core body and the conductive coil body, thereby ensuring that the performance of the inductive device is not affected by high temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the overall structure of the inductive device of the DCDC converter of the utility model assembled on the PCB;

[0021] Figure 2 It is a side schematic diagram of the overall structure of the inductive device of the DCDC converter of the utility model assembled on the PCB;

[0022] Figure 3 It is a side structural schematic diagram of the inductive device of the DCDC converter of the utility model;

[0023] Figure 4 The utility model is a flow chart of the welding processing method of the inductive device of the DCDC converter.

[0024] Among them, 10 is a magnetic conductor, 101 is a winding pole, 102 is an end of the magnetic conductor, 103 is a metal electrode at the end of the magnetic conductor, 20 is a coil, 201 is an end of the coil, 30 is an electrical connector, 40 is a circuit PCB board, 401 is a pad on the circuit PCB board, and 50 is an inductive device. DETAILED DESCRIPTION

[0025] Aiming at the current problem of insufficient solderability in the direct winding welding process of inductive devices such as the patch core of a DCDC converter, the utility model provides an inductive device, comprising: a magnetic conductor, the magnetic conductor is provided with a winding post and two ends, the ends are provided with metal electrodes, the winding post and the metal electrode are arranged in parallel between the two ends; a conductive coil, the conductive coil is wound on the winding post of the magnetic conductor, the end of the conductive coil is arranged on the metal electrode at the end of the magnetic conductor and forms physical contact with the metal electrode; an electrical connector is a solder body, which wraps the end of the conductive coil in a local ellipsoidal or film shape, is arranged on the metal electrode of the magnetic conductor, and is used to physically contact with the end of the conductive coil and the metal electrode of the magnetic conductor and the circuit PCB board to form an interconnected solder joint. Preferably, the magnetic conductor includes at least two metal electrodes, which are arranged on the same end or on different ends. The conductive coil also includes a metal conductive wire core and an insulating film; the insulating film covers and insulates the metal conductive wire core. The cross-section of the conductive wire core of the coil is circular or square, and the insulating film of the conductive coil has a temperature resistance between 130°C and 240°C. The electrical connector includes a solder body, the solder body includes tin, and the melting temperature of the solder body is ≤400°C.

[0026] The present invention and its beneficial effects will be further described in detail below in conjunction with specific implementations and the accompanying drawings of the specification, but the specific implementations of the present invention are not limited thereto.

[0027] See also Figures 1 to 3 The structure of an inductive device 50 of the DCDC converter of the utility model includes a magnetic conductor 10, wherein the magnetic conductor 10 contains a winding post 101, an end 102, and a metal electrode 103 on the end; a coil 20 is wound on the winding post 101 of the magnetic conductor 10, and the end of the coil 20 is 201, and the end 201 of the coil 20 is arranged on the metal electrode 103 of the magnetic conductor 10; then, an electrical connector 30 is arranged above the end 201 of the coil 20, and the electrical connector 30 is partially ellipsoidal, and the electrical connector 30 is in physical contact with the end 201 of the coil 20, the metal electrode 103 of the magnetic conductor 10, and the pad 401 of the circuit PCB board 40 to form an interconnected solder joint of electrical connection. The coil 20 is a conductive coil, which is wound by enameled wire or three-layer insulated wire, and the insulation film of the coil has a temperature resistance between 130°C and 240°C.

[0028] See also Figure 2, is a side view of the overall structure of the welding connection between the inductive device and the circuit PCB board. Figure 2 It can be seen that the electrical connection between the inductive device and the pad 401 of the circuit PCB board 40 is achieved through the electrical connector 30. The metal electrode 103 of the magnetic core body of the inductive device and the end 201 of the coil will not be in direct contact with the PCB pad 401, so there is no need to worry about the oxidation solder mask or insulation film residue of the metal electrode causing welding reliability problems. Preferably, the magnetic conductor 10 is a magnetic core, the electrical connector 30 is a solder body, including but not limited to lead-free tin or tin beads used for welding, and the inductive device 50 is a transformer. The circuit PCB board 40 is a carrier board for electronic components of a DCDC converter circuit with a power of 3W or less. Preferably, the inductive device 50 is a transformer. The DCDC converter can also be called a DCDC converter.

[0029] See also Figure 4 , is a flow chart of the inductive device welding processing method of the DCDC converter of the utility model. The manufacturing method of the DCDC converter of the utility model includes the welding processing link of the patch transformer and the circuit PCB board, and specifically includes the following processing process:

[0030] Step 1: providing a magnetic core 10, and winding a coil on a winding column of the magnetic core to make a chip transformer;

[0031] Step 2: Weld the ends of the transformer coil to the metal electrodes of the magnetic core by pulse spot welding or hot pressing welding;

[0032] Step 3: Use laser to ablate the ends of the coil and the surface of the metal electrode at the same time, ablate the insulating film residue on the end of the coil wire and the insulating film residue on the metal electrode, so that the end of the coil wire and the surface of the metal electrode of the magnetic core are clean;

[0033] Step 4: Place the electrical connector 30 on the end of the coil and the metal electrode. Specifically, a ball planting process or a low-temperature tinning process or other welding process can be used to make the tin physically contact with the coil end, the core metal electrode and the pad of the circuit PCB board to form interconnected solder joints. After the interconnected solder joints are cooled, the welding of the chip transformer and the circuit PCB board is completed.

[0034] Preferably, in step one, the transformer coil is wound by enameled wire or three-layer insulated wire, and the temperature resistance of the coil is between 120°C and 240°C.

[0035] Preferably, the power of laser ablation in step three does not exceed 3W.

[0036] Preferably, the insulating film of the laser ablated coil in step three has a temperature resistance between 130° C. and 240° C.

[0037] Through the above manufacturing method of the DCDC converter, in step three, the metal electrode is accurately positioned by laser ablation, and the insulating film of the wire end part of the coil located on the metal electrode is removed, and the surface oxide layer of the metal electrode itself is also removed, so as to realize the clean treatment of all metal surfaces in the welding area of ​​the interconnection solder joint, and the whole process only treats the surface of the metal electrode, and will not cause damage to the coil insulation layer outside the metal electrode, thereby ensuring the reliability of the insulation film performance of the coil. Secondly, the laser ablation power does not exceed 3W, the energy is low, and the temperature generated instantly is relatively low, which does not affect the mechanical strength and electrical performance of the magnetic core body. In step four, in the process of supplementing the electrical connector, the transformer coil insulation film is not immersed in a high-temperature tin furnace, and the magnetic core body is not immersed in high temperature. It is a relatively low-temperature welding process, so that the inductive device can avoid the residual solder resistance of the insulating film, welding thermal oxidation and magnetic core fragmentation caused by high-temperature tinning while supplementing the new coating, thereby improving the welding reliability of the DCDC converter power supply product, and avoiding the degradation or failure of the performance of the inductive device itself caused by high temperature.

[0038] The above are only preferred embodiments of the utility model. It should be noted that the above preferred embodiments should not be regarded as limiting the utility model, and its protection scope should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the application of the utility model, and these improvements and modifications should also be regarded as the protection scope of the utility model.

Claims

1. An inductive device, characterized in that: include: A magnetic conductor, wherein the magnetic conductor is provided with a winding post and two ends, the ends are provided with metal electrodes, and the winding post and the metal electrode are arranged parallel to each other between the two ends; A conductive coil, wherein the conductive coil is wound on a winding column of a magnetic conductor, and an end of the conductive coil is arranged on a metal electrode at an end of the magnetic conductor and forms physical contact with the metal electrode; The electrical connector is a solder body that wraps the end of the conductive coil in a partial ellipsoidal or film shape and is arranged on the metal electrode of the magnetic conductor to physically contact the end of the conductive coil, the metal electrode of the magnetic conductor and the circuit PCB board to form an interconnected solder joint.

2. The inductive device according to claim 1, characterized in that: The conductive coil also includes a metal conductive wire core and an insulating film; the insulating film covers and insulates the metal conductive wire core.

3. The inductive device according to claim 2, characterized in that: The cross section of the conductive wire core of the conductive coil is circular or square, and the insulation film of the conductive coil has a temperature resistance between 130° C. and 240° C.

4. The inductive device according to claim 1, characterized in that: The electrical connector includes a solder body, the solder body includes tin, and the melting temperature of the solder body is ≤400°C.

5. A DCDC converter, comprising the inductive device and a circuit PCB board according to any one of claims 1 to 4, characterized in that: The working power of the inductive device is ≤3W.

6. The DCDC converter according to claim 5, characterized in that: The input voltage of the inductive device is between 2V and 6V, the output voltage is between 2V and 6V, and the input and output isolation withstand voltage is 2500VDC.

7. The DCDC converter according to claim 5, characterized in that: The inductive device of the DCDC converter has a length between 5.5 mm and 6.3 mm, a width between 2.9 mm and 3.5 mm, and a height of ≤2.4 mm.

8. The DCDC converter according to claim 5, characterized in that: The packaging structure of the DCDC converter is a surface mount package, a SIP package or a DIP package.

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