JP2013172055A - Coil component and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coil component which allows high temperature reflow to be applied thereto and is superior in vibration resistance.SOLUTION: With respect to the coil component, a coil electrode 12 having Cu as a main component and a terminal electrode 16 having Cu as a main component are electrically and mechanically connected by solder in which bar-shaped metallic compounds 23 with CuSn as nuclei are dispersed in an Sn alloy 22, and a region including the coil electrode 12 and the solder is molded to constitute an outer package 19. Because of this constitution, the solder can be prevented from flowing out of the outer package 19 even when being molten.

Description

  The present invention relates to a coil component used in various electronic devices and a manufacturing method thereof.

  In recent years, there has been a demand for lead-free soldering, and as a result, the soldering temperature has risen, and when soldering is performed internally, such as coil parts, the internal solder is also melted and exposed to the outside during reflow soldering. there is a possibility. For such a problem, a method has been proposed in which Cu spheres are mixed in solder, a metal compound is generated, and the Cu spheres are connected to each other to inhibit fluidity even when the solder melts.

  As prior art document information related to the invention of this application, for example, Patent Document 1 is known.

JP 2002-261105 A

  In the conventional configuration, it is necessary to increase the amount of Cu spheres in order to sufficiently connect the Cu spheres. However, when the percentage of Cu spheres increases, voids are likely to occur in the solder after melting, and solder with a high percentage of Cu spheres is used for internal connection of coil parts, etc. When used in a device to be added, reliability such as the soldering part being easily broken by this vibration becomes a problem. In view of this problem, an object of the present invention is to provide a coil component that prevents solder from being melted to the outside during reflow soldering, prevents voids in the solder, and has excellent vibration resistance.

In order to solve the above problems, the present invention provides a solder in which a coil electrode containing Cu as a main component and a terminal electrode containing Cu as a main component are dispersed in a rod-like metal compound having Cu ₃ Sn as a core in an Sn alloy. The outer body is configured by molding the region including the coil electrode and the soldering portion that is electrically and mechanically connected.

With the above configuration, even when the Sn alloy in the internal solder melts during reflow soldering, the rod-shaped metal compound having Cu ₃ Sn as a core prevents fluidity and prevents the solder from coming out of the outer package. In addition, the generation of voids in the solder can be prevented and a coil component having excellent vibration resistance can be obtained.

The perspective view of the coil component in one embodiment of this invention Part A enlarged view in FIG. Sectional drawing of the BB line in FIG. The figure explaining the manufacturing method of the coil components in one embodiment of this invention The figure explaining the manufacturing method of the coil components in one embodiment of this invention The figure explaining the manufacturing method of the coil components in one embodiment of this invention The figure explaining the manufacturing method of the coil components in one embodiment of this invention The figure explaining the manufacturing method of the coil components in one embodiment of this invention

  Hereinafter, a coil component according to an embodiment of the present invention will be described with reference to the drawings.

  1 is a perspective view of a coil component according to an embodiment of the present invention, FIG. 2 is an enlarged view of a portion A in FIG. 1, FIG. 3A is a cross-sectional view taken along the line BB in FIG. ) Is an enlarged view of a portion C in FIG.

  In FIG. 1 to FIG. 3, a coil electrode 12 made of an insulating-coated Cu wire 11 is wound around a core 13 of a drum core 15 having flanges 14 at both ends of the core 13, and the coil drawn out from the drum core 15. The region including the coil electrode 12 and the soldered portion 17 is electrically and mechanically connected by soldering to the electrode 12 and the terminal electrode 16 made of a phosphor bronze plate attached to one flange 14 of the drum core. These are molded with resin to form the exterior body 19 to constitute a coil component.

  The terminal electrode 16 has an external connection electrode portion 20 that is partially exposed to the exterior of the exterior body 19 and is connected to a mounting substrate (not shown), and an interior that protrudes from the external connection electrode portion 20 inside the exterior body 19. The coil electrode 12 is connected to the internal connection electrode portion 21 by soldering, and a region including the portion 17 soldered to the coil electrode 12 is molded with resin.

The soldered portion 17 is in a state in which a rod-like metal compound 23 having Cu ₃ Sn as a nucleus is dispersed in an Sn alloy 22 made of an Sn—Ag—Cu alloy.

The rod-shaped metal compound 23 is in a state where the central portion is rod-shaped Cu ₃ Sn and the periphery thereof is covered with Cu ₆ Sn ₅ .

  Here, the bar shape means a shape whose length is five times or more the width.

With the above configuration, when the coil component is mounted on the printed circuit board and reflow soldering is performed, the Sn alloy 22 in the soldered portion 17 is exposed to the atmosphere of about 250 ° C. in the reflow soldering furnace. Although it melts because the phase temperature is about 220 ° C., the rod-shaped metal compound 23 having Cu ₃ Sn as a core does not melt because the melting point is 400 ° C. or higher, and these rod-shaped metal compounds 23 are dispersed in the Sn alloy 22. Therefore, it cannot flow easily, and the molten Sn alloy 22 can be prevented from coming out of the exterior body 19.

  Next, the manufacturing method of the coil component in one embodiment of this invention is demonstrated using FIGS.

  First, as shown in FIG. 4, the drum core 15 is attached to the terminal electrode 16.

  The terminal electrode 16 is formed by pressing a phosphor bronze plate having a thickness of 0.1 mm. The terminal electrode 16 protrudes from the pair of external connection electrode portions 20 and connects the coil electrode 12 to the external connection electrode portion 20. The connection electrode portion 21 is integrally formed. In the present embodiment, the pair of external connection electrode portions 20 are connected to each other by the frame portion 24 so as to form a hoop so that they can be continuously produced. Yes.

  Further, the frame portion 24 is provided with a pair of protrusions 25 for temporarily fixing the Cu wire 11 when the coil electrode 12 is wound around the drum core 15.

  At this time, the surface of the hoop-shaped terminal electrode 16 may be Sn-plated.

  The drum core is made of a Ni-Zn ferrite core or the like, and has a shape having disk-shaped ridges 14 at both ends of a cylindrical winding core 13. The diameter of the disk-shaped ridge 14 is 1.5 mm. ~ 2.5 mm, and the height dimension of the core 13 and the flanges 14 at both ends is about 0.8 mm to 1.5 mm. In this embodiment, the diameter dimension of the flange 14 is 1.8 mm, A drum core having a height of 1.35 mm is used.

  Then, the drum core 15 is pasted using an adhesive or the like so as to straddle the 20 parts of the pair of external connection electrode portions of the terminal electrode 16.

  Next, as shown in FIG. 5, the Cu wire 11 is wound around the drum core 15 a predetermined number of times to form the coil electrode 12.

  The Cu wire 11 is a wire having an insulating film made of an insulating resin such as polyurethane resin and having a wire diameter of about 0.03 mm to 0.08 mm. After being wound and temporarily fixed, the wire is drawn along the internal connection electrode portion 21 of one terminal electrode 16 and wound around the core 13 of the drum core 15 a predetermined number of times. Thereafter, the wire is drawn along the internal connection electrode portion 21 of the other terminal electrode 16 and wound around the other protrusion 25 for one turn or more to temporarily fix the winding end side.

  In this manner, the coil wire 12 is formed by winding the Cu wire 11 around the drum core 15 around the core 13. In this embodiment, the coil electrode 12 is formed by winding a Cu wire 11 having a wire diameter of 0.03 mm for 150 turns.

  Thereafter, the coil electrode 12 is continuously formed on the adjacent hoop-shaped drum core 15 without cutting the Cu wire 11. At this time, the plurality of drum cores are connected by the Cu wire 11.

  Next, the insulating film of the Cu wire 11 in the portion along the internal connection electrode portion 21 corresponding to the portion to be soldered is peeled off by a carbon dioxide laser (not shown), and then the solder paste 26 is applied.

  The solder paste 26 may be applied by a dispenser or a pin transfer method. As in this embodiment, the area of the internal connection electrode portion 21 to be soldered is about 0.3 mm × 0.2 mm. If narrow, application by pin transfer is preferred.

  Then, soldering is performed by irradiating the solder paste 26 with YAG laser light 27 as shown in FIG. As the solder paste 26, a solder particle made of Sn alloy 22 made of Sn-3Ag-0.5Cu alloy and having a diameter of about 30 μm mixed with Cu spheres having a diameter of about 7 μm and further mixed with a flux is used.

  At this time, the mixing ratio of Cu spheres is set to about 30% by weight. Further, the irradiation time of the YAG laser beam 27 is set to about 0.25 seconds, whereby the temperature of the solder is instantaneously increased to about 450 ° C.

Thus, by rapidly increasing the temperature of the solder to the high temperature by the YAG laser beam 27, the Cu sphere or the coil electrode 12 mixed with the solder paste 26, the Cu of the terminal electrode 16 and the Sn alloy 22 react with each other, and Cu _3. A rod-shaped metal compound 23 having Sn as a nucleus is generated. Furthermore, since the heating is performed with the laser beam, after the temperature suddenly rises only at the part to be soldered, the heat escapes toward the terminal electrode 16 and the Cu wire 11, and the temperature of the solder suddenly falls. Since it solidifies, more rod-like metal compound 23 can be left in the solder.

  The rod-shaped metal compound 23 has a width of about 1 to 8 μm and a length of 5 times or more the width.

  By dispersing such a large rod-shaped metal compound 23 in the Sn alloy 22, even if the Sn alloy 22 melts at the reflow temperature, the fluidity is hindered, so that the solder is outside the exterior body 19. It can eliminate melting out.

Even if Cu spheres are not mixed, the rod-like metal compound 23 having Cu ₃ Sn as a nucleus can be formed by the Cu wire 11 of the coil electrode 12 or the phosphor bronze Cu of the terminal electrode 16 and the Sn alloy 22. However, in order to produce more rod-shaped metal compound 23, it is desirable to mix Cu by 20% or more by weight.

  However, when the amount of Cu spheres increases, voids are likely to be generated in the solder.

  In order to better disperse the rod-like metal compound 23, it is desirable that the size of the Cu sphere is 1/3 or less that of the Sn alloy 22.

  The Cu mixed with the Sn alloy 22 may not be spherical as long as it is sufficiently mixed.

Moreover, in order to produce the rod-shaped metal compound 23 having Cu ₃ Sn as a nucleus, a higher temperature is advantageous, and it is necessary to instantaneously set the temperature to 400 ° C. or higher.

  However, it is necessary not to exceed the melting point of Cu. Further, the heating time should be as short as possible so that the temperature can be rapidly lowered after heating, and more preferably 0.5 seconds or less.

  Furthermore, before irradiating the YAG laser beam 27, it is desirable to preheat the solder paste 26 to be soldered to about 100 to 150 ° C. in advance.

  By doing in this way, the extra component with high volatility in a flux can be skipped and generation | occurrence | production of a void can further be suppressed.

  Next, as shown in FIG. 7, the entire body including the drum core 15 including the coil electrode 12 and the soldered portion 17 of the terminal electrode 16 is molded with an epoxy resin to form an exterior body 19.

  In addition, you may use for this exterior body 19 what disperse | distributed magnetic substance powder to the epoxy resin.

  Next, the excess portion of the external connection electrode portion 20 of the terminal electrode 16 and the Cu wire 11 protruding from the exterior body 19 are cut off from the hoop material to cut the external connection electrode portion 20 of the terminal electrode 16 from the bottom surface of the exterior body 19. The coil component as shown in FIG. 8 is completed by bending toward the end.

  In the present embodiment, the terminal electrode 16 has been described as being continuously formed in a hoop shape. However, it may be a single piece, and an internal connection electrode portion 21 that protrudes from the external connection electrode portion 20 is provided. As described above, the coil electrode 12 may be soldered and connected to the external connection electrode portion 20 inside the exterior body 19 without providing the internal connection electrode portion 21, and the same effect as this embodiment Can be obtained.

  The coil component and the manufacturing method thereof according to the present invention provide a coil component that prevents the solder from being melted to the outside during reflow soldering, prevents the generation of voids in the solder, and has excellent vibration resistance. Can be industrially useful.

11 Cu wire 12 Coil electrode 13 Core 14 鍔 15 Drum core 16 Terminal electrode 17 Soldered part 19 Exterior body 20 External connection electrode part 21 Internal connection electrode part 22 Sn alloy 23 Rod metal compound 24 Frame part 25 Projection part 26 Solder Paste 27 YAG laser light

Claims (3)

A coil electrode containing Cu as a main component and a terminal electrode containing Cu as a main component are formed of Cu _{3 in the} Sn alloy.
It is electrically and mechanically connected with a solder in which a rod-shaped metal compound having Sn as a core is dispersed, and an outer body is formed by molding the coil electrode and the region containing the solder. Coil parts. A solder paste in which Sn alloy particles made of Sn—Ag—Cu alloy and flux are mixed is arranged so as to connect a coil electrode containing Cu as a main component and a terminal electrode containing Cu as a main component. By melting the solder paste, the coil electrode and the terminal electrode are electrically and mechanically connected while forming a rod-like metal compound having Cu ₃ Sn as a core, and the coil electrode is molded. A manufacturing method of a coil component as a feature. 3. The method of manufacturing a coil component according to claim 2, wherein the solder paste is further mixed with Cu powder.

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