JP3478052B2 - Surface mount type inductor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type inductor, for example, a surface mount type inductor used in a small electronic device such as a mobile phone. 2. Description of the Related Art As shown in FIG. 5 , this type of surface mount type inductor includes a winding part 2c and two legs 2a and 2b provided at both ends of the winding part 2c. A surface mount type inductor 1 having a so-called horizontal type core 2 has been proposed. The winding 5 is wound around the winding part 2c. Both ends 5a and 5b of the winding 5 are thermocompression-bonded to terminal electrodes 4a and 4b provided on the legs 2a and 2b of the core 2, and are electrically connected. A protective material 6 is provided on the upper part of the core 2, and the upper part of the winding 5 wound around the winding part 2 c is covered with the protective material 6. The inductor 1 is soldered to the mounting electrode 8a provided on the circuit board 8 or the like by flow solder using molten solder or reflow solder using cream solder. Implemented. When mounting the inductor 1 on the circuit board 8 by flow soldering, it is necessary to temporarily fix the inductor 1 to the circuit board 8 with an adhesive 9. The adhesive 9 is usually applied onto the circuit board 8 with a substantially constant thickness by a printing method, a dispenser method, or the like. [0004] However, the inductor 1 is
a, 2b, the bottom surface 2d of the winding portion 2c and the circuit board 8
Has a large gap with the surface. For this reason, with the normal thickness of the adhesive 9, the adhesive 9 could not reach the winding 5, and the inductor 1 could not be temporarily fixed to the circuit board 8. Therefore, apart from other electronic components, in the case of the inductor 1, it is conceivable to increase the amount of the adhesive 9, but there is a problem that the work of applying the adhesive 9 becomes complicated. Further, in handling the inductor 1 when mounting the inductor 1 on the circuit board 8 or the like, the suction nozzle often sucks the central portion of the winding portion 2c. However, the winding part 2c of the inductor 1 is
a and 2b, the winding portion 2c
The mechanical strength is weak with respect to the vertical load applied to the central portion of the winding portion 2c, and the impact force of the suction nozzle may cause cracks or cracks near the center of the winding portion 2c, for example. SUMMARY OF THE INVENTION It is an object of the present invention to provide a surface mount type inductor which can reliably perform temporary fixing during flow soldering and is strong against a load applied during handling. In order to achieve the above object, a surface mount type inductor according to the present invention comprises (a) a winding portion and two windings provided at both ends of the winding portion. (B) a winding wound around a winding portion; and (c) a temporary fixing coating material disposed only on the bottom surface of the winding portion. When disposed only on the (d) core, the upper surface is a flat
And a protective material, planar previously in contact with the substrate during mounting the legs (e) Core
Has an end face, (f) temporary fixing coating material has a convex curved surface in one direction in the longitudinal direction or width direction of at least the winding portions, (g) projecting the temporary fixing coatings The top of the curved surface is
Characterized by being receded from the tip surface of the core leg by 0 to 150 μm. When the surface mount type inductor is mounted by flow soldering, the inductor protrudes from the bottom surface of the winding portion in a convex shape.
The temporary fixing coating material sufficiently reaches the adhesive applied to the surface of the circuit board or the like, and the inductor is temporarily fixed to the circuit board or the like. At this time, excess adhesive spreads toward the outside of the top portion of the convex curved surface of the temporary fixing Koti <br/> ring member, provisionally
The contact area between the fixing coating material and the adhesive increases. In addition, since the temporary fixing coating material is disposed on the bottom surface side of the winding portion, the temporary fixing coating material is disposed between two legs provided at both ends of the core. Configuration. Then, the temporary fixing coating material functions as a reinforcing material and a support material for the winding portion bridged between the leg portions. An embodiment of a surface mount type inductor according to the present invention will be described below with reference to the accompanying drawings. As shown in FIGS. 1 and 2, the surface mount type inductor 11 is roughly fixed to a core 2, a winding 5, and a temporary fixing.
And a coating material 13. Core 2
Is a so-called horizontal type comprising a winding part 2c and two legs 2a and 2b provided at both ends of the winding part 2c. As a material of the core 2, a nonmagnetic ceramic material or a magnetic material such as ferrite is used. Ag, Cu, Ag- is provided on the tip side of the legs 2a, 2b.
Terminal electrodes 4a and 4b made of Pd or the like are provided, respectively. The winding 5 is wound around a winding portion 2c of the core 2. Both ends 5a and 5b of the winding 5 are fixed to terminal electrodes 4a and 4b provided on the core 2 by means such as thermocompression bonding, and are electrically connected. As the winding 5, for example, a copper wire or the like coated with urethane resin is used, and the urethane resin is scattered by heat applied at the time of thermocompression bonding at both end portions 5 a and 5 b, and the copper wire is exposed. Will be. A protective material 12 made of resin is provided on the upper part of the core 2.
Is provided, and the upper part of the winding 5 wound around the winding part 2 c is covered with the protective material 12. The upper surface of the protection member 12 is a flat surface. The reason why the upper surface of the protective material 12 is flat is that when the inductor 11 is mounted on the circuit board 8, the suction by the suction nozzle can be surely performed, and the winding 5 is damaged by the suction by the suction nozzle. This is to prevent The protective material 12 is, for example, a material in which the winding 5 is wound around the winding portion 2 c of the core 2, immersed in a resin bath from the upper surface side of the core 2 to apply resin to the upper portion of the core 2, It is formed by lifting from a resin bath and curing the resin by light or heat. On the other hand, a coating material 13 made of resin or the like
Is disposed on the bottom surface 2d of the winding portion 2c of the core 2 and covers a lower portion of the winding 5 wound around the winding portion 2c. That is, the coating material 13 has a structure in which the winding portion 2c is sandwiched from both sides together with the protection material 12. The surface of the coating material 13 is a curved surface that is convex in the length direction (the arrow X direction in FIG. 1) and the width direction (the arrow Y direction in FIG. 1) of the winding portion 2c. The top 13a of the convex curved surface is located at a substantially central portion. And the top 1
The difference d between 3a and the tip surfaces of the legs 2a and 2b of the core 2 is 0 to
It is desirable to form the coating material 13 so as to have a range of 150 μm. That is, it is desirable that the top portion 13a is retracted from the tip end surfaces of the leg portions 2a and 2b by 0 to 150 μm. As shown in FIG. 3, for example, the coating material 13 is formed by attaching the core 2 around which the winding 5 is wound to the legs 2a, 2b.
Are arranged on the holding plate 14 with the
The liquid coating material 13 is applied to the winding part 2c between the legs 2a and 2b. At this time, 60 Pa · s (Pascal · second) is used as the liquid coating material 13.
If a material having a certain degree of viscosity is used, the liquid coating material 13 stays on the bottom surface 2d of the winding part 2c between the legs 2a and 2b, and the top 13a of the coating material 13 and the legs 2a, 2b.
The difference d from the tip surface of 2b can be in the range of 0 to 150 μm. In the core 2 to which the liquid coating material 13 is applied, the liquid coating material 13 is cured by light or heat. The surface mount type inductor 1 thus obtained
When 1 is surface-mounted by flow soldering, the upper surface of the protective material 12 is sucked by the suction nozzle, and is placed at a mounting position on the circuit board 8 or the like as shown in FIG. An adhesive 9 is applied to the circuit board 8 in advance by printing or the like, and the top 13 a of the coating material 13 contacts the adhesive 9. As a result, the excess adhesive 9 spreads outward from the top 13a, the contact area between the coating material 13 and the adhesive 9 increases, and the inductor 11 is securely temporarily fixed to the circuit board 8. Further, since the coating material 13 is disposed on the bottom surface 2d side of the winding portion 2c, it also functions as a reinforcing material and a support material for the winding portion 2c. Therefore, even if a load in the vertical direction is applied to the winding part 2c by the suction nozzle during mounting or the like,
The coating material 13 can prevent the core 2 from being damaged. The surface mount inductor according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the invention. Of the above embodiment
The coating material for temporary fixing has a convex curved surface in both the length direction and the width direction of the winding portion 2c, but is not limited thereto, and is not limited to this. Or it may have a curved surface that is convex in one of the width directions. Further, the protective material 12 may be formed by the following method. That is, after the winding 5 is wound around the winding portion 2 c of the core 2, the resin is cured from the upper surface of the core 2 by light or heat or the like by dipping into a mold containing the resin. The protective member 12 can be formed by being removed from the mold. Alternatively, a resin plate may be bonded to the upper surface of the core 2. As is apparent from the above description, according to the present invention, at least one of the length direction and the width direction of the winding portion is convex on the bottom surface of the winding portion of the core. Since the temporary fixing coating material having a curved surface is arranged, when the inductor is surface-mounted on a circuit board or the like by flow soldering, the temporary fixing coat is applied to the adhesive applied to the circuit board or the like. The top of the bonding material contacts, the excess adhesive spreads outward from the top, the contact area between the temporary fixing coating material and the adhesive increases, and the temporary fixing of the inductor to the circuit board is ensured. Can be. Further, since the temporary fixing coating material is provided on the bottom surface side of the winding portion of the core, it also functions as a reinforcing material and a supporting material for the winding portion. Therefore, even when a vertical load is applied to the winding portion by the suction nozzle during mounting or the like, breakage of the core can be prevented by the temporary fixing coating material.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a bottom perspective view showing one embodiment of a surface mount inductor according to the present invention. FIG. 2 is a partial cross-sectional view of the surface mount inductor shown in FIG. FIG. 3 is an exemplary perspective view showing a procedure for forming a coating material of the surface-mount inductor shown in FIG. 1; FIG. 4 is a partial cross-sectional view showing a state where the surface-mount inductor shown in FIG. 1 is temporarily fixed to a circuit board. FIG. 5 is a front view showing a conventional surface mount inductor. [Description of Signs] 2 cores 2a, 2b leg 2c winding part 5 winding 11 surface mount inductor 13 coating material

Continuation of the front page (56) References JP-A-8-124748 (JP, A) JP-A-2-43708 (JP, A) JP-A-10-163033 (JP, A) JP-A-5-77909 (JP) , U) Japanese Utility Model Application Hei 4-99807 (JP, U) Japanese Utility Model Application 57-200014 (JP, U) Japanese Utility Model Application Hei 1-1633311 (JP, U) Japanese Utility Model Application 50-74449 (JP, U) (58) Field surveyed (Int.Cl. ⁷ , DB name) H01F 27/02 H01F 27/06

Claims (1)

(57) [Claim 1] A core composed of a winding part and two legs provided at both ends of the winding part, and a core wound around the winding part. and a winding, and a temporary fixing Kotin <br/> ingredients disposed only on the bottom surface of the winding part is disposed only on the top of the core, the coercive upper surface is planar
And a leg portion of the core, the leg portion of the core being in contact with a substrate at the time of mounting.
Surface, and the temporary fixing coating material has a convex curved surface in at least one of a length direction or a width direction of the winding portion, and the convex curved surface of the temporary fixing coating material. The top of the front
A surface-mounted inductor, wherein the core is recessed from 0 to 150 μm from a tip end surface of a leg portion of the core .