WO2017070832A1

WO2017070832A1 - Surface-mounted inductor and manufacturing method therefor

Info

Publication number: WO2017070832A1
Application number: PCT/CN2015/092899
Authority: WO
Inventors: 黄智�
Original assignee: 墨尚电子技术(上海)有限公司
Priority date: 2015-10-27
Filing date: 2015-10-27
Publication date: 2017-05-04
Also published as: CN208489108U

Abstract

A surface-mounted inductor and a manufacturing method therefor. The inductor includes: a rolled coil (1) which is formed by rolling a short side surface (SW) of a flat copper wire perpendicular to a screw axis (AX), so that two end parts (1a) of the rolled coil (1) are located at an outermost periphery; an inductor core body (2) which is formed by sealing the rolled coil (1) to an interior by adopting a mixed material formed by magnetic powder and resin, and forms an upper surface and a lower surface (2a), and four side faces, wherein the upper surface and the lower surface (2a) are perpendicular to the screw axis (AX) of the rolled coil (1), and a wire collecting groove (2c) is arranged on the lower surface (2a); and an external electrode (3), wherein the external electrode (3) is formed by completing a 90-degree rotation of the two end parts (1a) of the rolled coil (1) inside the inductor core body (2) so as to enable a long side surface (SL) of the flat copper wire of the rolled coil (1) to be perpendicular to the screw axis (AX) and then a wire to come out from the same side face of the inductor core body (2), and then enable the end parts (1a) outside the inductor core body (2) to be collected, after being bent, in the wire collecting groove (2c) on the lower surface (2a) of the inductor core body (2). Therefore, additional eddy current loss is not brought about; in addition, direct current resistance can be reduced, and an inductance value of an inductor is improved. The manufacturing method is applicable to serialized design and production of surface-mounted inductors.

Description

Surface mount inductor and manufacturing method thereof

Technical field

The invention relates to a surface mount inductor and a method of manufacturing the same.

Background technique

Surface mount inductors formed by integral molding have been widely used in recent years. Such inductors generally include a coil, a core composed of a magnetic powder and a resin covering the coil, and an external electrode.

In the prior art, there are two methods of manufacturing surface mount inductors.

A manufacturing method widely used in the industry is to accommodate a prefabricated coil in a mold composed of an upper mold and a lower mold, and then the lead end of the coil is welded to the outer lead frame, and a part of the lead frame is used by the mold. The coil is fixed in the cavity together with the coil, and then the composite material composed of magnetic powder and resin is filled into the cavity, and they are press-formed by a mold and a punch under high pressure, and finally the outer lead frame is punched and bent. An external electrode is formed. The manufacturing method is that the external lead frame and the lead end of the coil are soldered inside the inductor, which occupies the internal space of the inductor and causes a large eddy current loss. This problem becomes more complicated in the case where the surface mount inductor is miniaturized. protruding.

Another manufacturing method is to arrange a coil formed by winding a flat copper wire on a preform formed of a composite material of magnetic powder and resin, and the preform may have a T shape (Chinese Patent Application Publication No.: CN102610363B) or U. The shape of the word (Chinese Patent Application Publication No.: CN103295754A, CN101859641B) accommodates the coil in a mold composed of a lower mold and an upper mold in such a manner that the leading end of the coil is sandwiched by the preform and the inner wall of the mold. The preform is then filled with a composite of magnetic powder and resin or filled with a preform formed of the composite, and then thermally compressed by a die and a punch to form a surface mount inductor. This manufacturing method requires coating a conductive paste on the surface of the core and curing it, and then performing a plating treatment to form an electrode. This manufacturing method is complicated by the need to pre-form the composite material of the magnetic powder and the resin, and the required preform has a problem of complicated shape and insufficient strength in the case where the surface mount inductor is miniaturized. And the manufacturing method The electrodes generally have five faces. In the trend of further miniaturization of electronic devices, the electrodes on the upper surface may be short-circuited with the shield plate, posing a certain risk.

In addition, there is known a method of manufacturing a surface mount inductor using a flat copper wire, as shown in Fig. 1, which is a schematic diagram of a prior art flat copper wire wound coil. It can be seen from the figure that there are two faces SL and SW perpendicularly intersecting the flat copper wire section SC, wherein the SL face intersects the section SC on the long side, which is called a long side face; wherein the SW face intersects the section SC on the short side , called the short side. The so-called vertical winding refers to a winding method in which the long side surface SL of the flat copper wire is perpendicular to the winding axis AX of the coil; correspondingly, the winding means that the short side surface SW of the flat copper wire is perpendicular to the coil A winding method for the winding of the screw axis AX. As can be seen in Figure 1, the flat copper wire wound coil has a natural advantage in forming the electrode, and the electrode can be easily formed by simply bending the end of the flat copper wire. However, the use of flat copper coils is very limited, and is basically only suitable for low-sensitivity large currents or thick surface-mount inductors. The reason is that for higher-sensitivity or thin surface-mount inductors, The required thickness of the flat copper wire is thin, which inevitably leads to the flatness ratio of the copper wire being too large, and it is difficult to be wound in a vertical winding manner; thus the copper wire size range that can be obtained is severely limited, and the surface mount inductor is increasingly thinned. Not suitable as a general solution.

Summary of the invention

In view of the above problems, the present application provides a surface mount inductor with a simple process and a manufacturing method thereof, which can reduce the occupation of the internal space of the inductor, and can avoid the appearance of an electrode on the upper surface of the inductor, and can reduce the DC resistance, improve the inductance value, etc. Improved features.

In order to achieve the above object, the present invention provides a technical solution including:

A surface mount inductor characterized by comprising:

a winding coil, which is formed by winding a short side of a flat copper wire perpendicular to a spiral axis such that both ends of the winding coil are located at the outermost periphery;

An inductor core, which is formed by sealing a wound coil and a resin, and sealing the wound coil into an inner surface, and forming an upper surface, a lower surface and four sides, the upper and lower surfaces being perpendicular to the Winding a spiral shaft of the coil, and the lower surface is provided with a wire receiving groove;

An external electrode that rotates both ends of the wound coil 90 degrees inside the inductor core such that a long side of the flat copper wire of the wound coil is perpendicular to the spiral After the shaft, the wire is taken out from the same side of the inductor core, and then the outer portion of the inductor core is bent and then received in the wire receiving groove of the lower surface of the inductor core.

Preferably, the surface mount inductor provided by the present invention is characterized in that

The 90 degree rotation includes a 90 degree rotation clockwise and a 90 degree rotation counterclockwise.

The shape of the wound coil includes a circular shape, a square shape, a rectangular shape, an elliptical shape, and a racetrack shape.

The present invention also provides a method of fabricating a surface mount inductor as described above, characterized in that it comprises:

Step one, providing a flat copper wire;

Step 2, forming a winding coil by winding a short side surface of the flat copper wire perpendicular to a spiral axis, so that both ends of the winding coil are located at the outermost circumference;

Step three, rotating the two ends of the winding coil 90 degrees, such that the long side of the flat copper wire is perpendicular to the screw axis;

Step four, mixing a plurality of magnetic powders and a resin to form a sealing material;

Step 5, integrating the winding coil and the sealing material to form an inductor core, such that the wound coil end after rotating 90 degrees protrudes from the same side of the inductor core, and the inductor core The lower surface forms a take-up groove;

In step six, the winding coil end protruding from the inductor core is bent and then received in the wire receiving groove of the inductor core to form an electrode.

Preferably, the method for manufacturing a surface mount inductor provided by the present invention is characterized in that

In the fifth step, the winding coil and the sealing material are integrated to include an injection molding method and a powder compression molding method.

Preferably, the method for manufacturing a surface mount inductor provided by the present invention is characterized in that after step 3, the method further comprises:

The end film of the wound coil is pre-stripped and immersed to form a reliable electrical connection.

Compared with the prior art, the surface mount inductor solution of the present application does not introduce an electrode material inside the inductor, so it does not bring additional eddy current loss, and can reduce the DC resistance and improve the inductance of the inductor; the process is simple and suitable. Serial design and production of surface mount inductors.

DRAWINGS

The above and other objects, features and advantages of the present invention will become apparent from the <RTIgt;

1 is a schematic view of a prior art flat copper wire wound coil;

Figure 2 is a winding elliptical coil rotated 90 degrees at the end of the first embodiment of the present invention;

Figure 3 is a perspective view showing the end portion of the first embodiment of the present invention which is not bent;

Figure 4 is a perspective view showing the surface mount inductance of the electrode at the end of the first embodiment of the present invention;

Figure 5 is a winding circular coil in which the end portion of the second embodiment of the present invention is rotated by 90 degrees;

Figure 6 is a perspective view showing the end portion of the second embodiment of the present invention which is not bent;

Figure 7 is a perspective view showing the surface mount inductance of the electrode of the second embodiment of the present invention;

Figure 8 shows a manufacturing flow diagram of the present invention.

Figure indication

AX --- winding coil screw shaft

SC --- Flat copper wire cross section

SL --- Flat copper wire long side

SW --- flat copper wire short side

1 --- winding coil

1a --- winding the end of the coil

2 ---Inductor core

2a --- Inductor core lower surface

2b --- Inductor core outlet side surface

2c --- Wire take-up groove on the lower surface of the inductor core

2d --- Wire take-up groove on the output side surface of the inductor core

2e --- Wire take-up groove on the opposite side of the output side of the inductor core

3 --- Inductive electrode

detailed description

For the electrode of the surface mount inductor, as described above, the method of using external lead frame soldering or preforming and coating the surface of the iron core with conductive paste and plating to form the electrode can not achieve a good effect. Applicant's improvement is to use the end of the copper coil itself to form the electrode. Considering the requirement that the bottom electrode of the inductor needs to be flat, the coil of the flat copper wire is a suitable consideration.

Example 1

The surface mount inductor according to the first embodiment has an outer dimension of 2.5 mm*2.0 mm*1.0 mm and is a small-sized thin inductor. As shown in FIG. 2, the short side surface SW of the designed flat copper wire is first wound perpendicularly to the screw axis AX to form a wound coil 1 having an elliptical shape so that two of the coils 1 The end portion 1a is located at the outermost portion, and the film of the end portion 1a of the wound coil is peeled off in advance and immersed in tin. The both end portions 1a of the wound coil 1 are rotated by 90 degrees so that the rectangular copper long side surface SL is perpendicular to the helical axis AX and then protrudes in parallel in the short axis direction of the elliptical shape. As shown in FIG. 3, the iron-based magnetic metal powder and the epoxy resin are mixed and granulated to form a sealing material, and the wound coil 1 and the sealing material are integrated into a mold by a powder hot press molding method to form an inductor core. 2, and forming an upper surface, a lower surface and four sides (only the lower surface 2a is shown in the drawing), the upper and lower surfaces must be perpendicular to the helical axis AX of the wound coil 1. A wire take-up groove 2c is formed on the lower surface 2a of the inductor core 2. The coil ends 1a that have been rotated by 90 degrees project in parallel from the same side 2b of the inductor core 2. As shown in FIG. 4, the coil end portion 1a is bent twice and then stored in the wire take-up groove 2c to form the electrode 3.

Example 2

The surface mount inductor according to the second embodiment has an outer dimension of 4.0 mm*4.0 mm*1.2 mm and is a small-sized thin inductor. As shown in FIG. 5, first, the flat copper short-side surface SW conforming to the design is wound perpendicularly to the winding coil axis AX to form a wound coil 1, and the wound coil 1 has a circular shape so that the coil 1 is wound. The two ends 1a are located at the outermost portion. Then, the two end portions 1a of the wound coil 1 are rotated by 90 degrees so that the flat copper long side surface SL is perpendicular to the winding coil axis AX, and is projected in parallel in the diameter direction of the circle, and the winding The film of the coil end portion 1a is peeled off in advance and immersed in tin. As shown in FIG. 6, the iron-based magnetic metal powder and the epoxy resin are kneaded, and the wound coil 1 and the sealing material are integrated into a mold by injection molding to form an inductor core 2, and an upper surface is formed. The lower surface and the four sides (only the lower surface 2a is indicated in the drawing), and the upper and lower surfaces are perpendicular to the helical axis AX of the wound coil 1. The coil end portion 1a rotated by 90 degrees protrudes in parallel from the same side face 2b of the inductor core 2. A wire take-up groove 2c is formed in the lower surface 2a of the inductor core 2 perpendicular to the coil screw axis, and wire take-up grooves 2d and 2e are formed on the line side surface 2b and the opposite side surfaces thereof, respectively. As shown in FIG. 7, the coil end portion 1a is bent twice and sequentially stored in the wire take-up grooves 2d, 2c, and 2e to form the electrode 3.

According to the two embodiments and the manufacturing flowchart of FIG. 8, it can be further understood that the surface mount inductor of the present invention comprises a wound coil 1, an inductor core 2, and an external electrode 3; wherein the coil 1 is flat The short side surface SW of the copper wire is wound perpendicularly to the spiral axis AX of the winding coil, so that both ends of the wound coil 1 are located at the outermost periphery; wherein the inductor core 2 is made of a mixed material of magnetic powder and resin, The winding coil 1 is sealed to the inside and forms an upper surface, a lower surface and four sides, the upper and lower surfaces being perpendicular to the spiral axis AX of the wire winding ring, and the lower surface 2a of the inductor core is provided with a wire receiving groove 2c. The external electrode 3 is such that the two ends of the wound coil 1 are rotated 90 degrees inside the inductor core 2 such that the long side SL of the flat copper wire is perpendicular to the screw axis AX and then exits from the same side of the inductor core 2, and then The outer end portion of the inductor core 2 is formed by being bent and then housed in the wire take-up groove 2c on the lower surface of the inductor core.

Since the winding process is suitable for flat copper wires of different flat ratios, the surface mount of the present invention can form a series of flat copper wires with different thicknesses and widths: for high inductance, only a thin flat copper is needed. The line is matched with a larger number of turns; for low-sensitivity values, a thicker flat copper wire is used with fewer turns. The two ends of the wound coil 1 are rotated 90 degrees inside the inductor core 2, so that the long side surface SL of the flat copper wire is bent perpendicular to the spiral axis AX, and the coil can be wound like a flat copper wire. Easily form electrodes, the process is very simple, and can reduce the occupation of the internal space of the inductor, which helps to reduce the DC resistance and increase the inductance value. The purpose of providing the wire take-up groove 2c on the lower surface 2a of the inductor core is mainly to form the bottom electrode 3 while reducing the influence of the electrode 3 on the overall inductance height.

The rotation of 90 degrees may include 90 degrees of clockwise rotation and 90 degrees of counterclockwise rotation, but internal rotation of 90 degrees must be completed inside the inductor core 2, and the long side surface SL of the flat copper wire is perpendicular to the spiral axis of the wound coil. AX to ensure the flatness of the external electrodes. Based on the characteristics of the flat copper wire, the rotation of 90 degrees also contributes to the positioning of the wound coil in the up and down and left and right directions in the molding cavity of the inductor core 2. The end film of the coil can be pre-stripped and immersed to form a reliable electrical connection. If the coil process is soft, the solder depth can be increased to increase the positioning capability.

The shape of the coil can be circular, square, rectangular, elliptical, racetrack, etc., and can be designed according to the shape of the surface mount inductor, and only needs to ensure that the coil end can be rotated 90 degrees inside the inductor core 2 from the inductor. The core can be lined out on the same side.

The outlet side of the inductor core 2 can also be provided with a take-up slot to reduce the influence on the size of the inductor, reduce the length of the mold support, and increase the support force of the coil support; at the same time, it can reduce the damage of the inductor when the coil is bent. probability.

The inductor of the present invention needs to seal the coil with a mixed material of magnetic powder and resin. The suitable packaging process can be powder press molding and injection molding, in particular, because the molding pressure of the injection molding package is smaller, and the injection molding is performed. After the mold is locked, the coil has a smaller shape variable, which is more suitable for high-precision molding. In summary, the present invention also relates to a method for fabricating a surface mount inductor, which comprises the steps of: forming a coil by winding a short side of the flat copper wire perpendicular to the spiral axis such that both ends of the coil are located at the outermost periphery. a process of rotating the two ends of the coil by 90 degrees so that the long side of the flat copper wire is perpendicular to the screw axis; a process of mixing the magnetic powder and the resin to form a sealing material; using an injection molding method or a powder press molding method The coil and the sealing material are integrated to form an inductor core, so that the coil end after rotating 90 degrees protrudes from the same side of the inductor core, and forms a lower surface of the inductor core. The process of the wire trough. The step of bending the end portion of the coil protruding from the inductor core and accommodating it in the wire receiving groove of the inductor core to form an electrode.

The previous description of the preferred embodiments is provided to enable any person skilled in the art to use or utilize the invention. Various modifications to these embodiments are obvious to those skilled in the art, and the general principles described herein may be applied to other embodiments without the use of inventive. Thus, the present invention is not intended to be limited to the embodiments shown herein.

Claims

A surface mount inductor characterized by comprising:

a winding coil, which is formed by winding a short side of a flat copper wire perpendicular to a spiral axis such that both ends of the winding coil are located at the outermost periphery;

An inductor core, which is formed by sealing a wound coil and a resin, and sealing the wound coil into an inner surface, and forming an upper surface, a lower surface and four sides, the upper and lower surfaces being perpendicular to the Winding a spiral shaft of the coil, and the lower surface is provided with a wire receiving groove;

An external electrode that rotates both ends of the wound coil 90 degrees inside the inductor core such that a long side of the flat copper wire of the wound coil is perpendicular to the spiral After the shaft, the wire is taken out from the same side of the inductor core, and then the outer portion of the inductor core is bent and then received in the wire receiving groove of the lower surface of the inductor core.
The surface mount inductor of claim 1 wherein

The 90 degree rotation includes a 90 degree rotation clockwise and a 90 degree rotation counterclockwise.
The surface mount inductor of claim 1 wherein

The shape of the wound coil includes a circular shape, a square shape, a rectangular shape, an elliptical shape, and a racetrack shape.
A method of manufacturing a surface mount inductor according to claim 1, comprising:

Step one, providing a flat copper wire;

Step 2, forming a winding coil by winding a short side surface of the flat copper wire perpendicular to a spiral axis, so that both ends of the winding coil are located at the outermost circumference;

Step three, rotating the two ends of the winding coil 90 degrees, such that the long side of the flat copper wire is perpendicular to the screw axis;

Step four, mixing a plurality of magnetic powders and a resin to form a sealing material;

Step 5, integrating the winding coil and the sealing material to form an inductor core, such that the wound coil end after rotating 90 degrees protrudes from the same side of the inductor core, and the inductor core The lower surface forms a take-up groove;

In step six, the winding coil end protruding from the inductor core is bent and then received in the wire receiving groove of the inductor core to form an electrode.
The method of claim 4 wherein:

In the fifth step, the winding coil and the sealing material are integrated to include an injection molding method and a powder compression molding method.
The method of claim 5, further comprising after step three:

The end film of the wound coil is pre-stripped and immersed to form a reliable electrical connection.
The method of claim 6 wherein:

The 90 degree rotation includes a 90 degree rotation clockwise and a 90 degree rotation counterclockwise.
The method of claim 6 wherein:

The shape of the wound coil includes a circular shape, a square shape, a rectangular shape, an elliptical shape, and a racetrack shape.