JP2002231533A - Surface-mounting type inductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve adhesive strength between a drum core and a base. SOLUTION: An inductor is provided with the base 2 made of an insulating material, a pair of terminals 3 and 3 that are in a state of positioning, and the drum core 4 wound by a winding 5 that is connected with the terminals 3 and 3. The drum core 4 is adhered to the upper surfaces of the base 2 and terminals 3 and 3 in a manner to stride the terminals 3 and 3. At least an adhering surface area 21 to the drum core 4 in the terminals 3 and 3 is in non-plating state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type inductor suitable for applications such as direct current superposition.

[0002]

2. Description of the Related Art In general, a surface mount type inductor has a pair of terminals attached to a base made of an insulating resin, and a wound drum core is fixed on the base by bonding, and a lead portion of the winding is fixed to each base. It has a structure to connect to terminals. Then, the surface-mounted inductor is mounted on the wiring board by soldering the pair of terminals to the pattern of the wiring board. In this case, since the pair of terminals are attached to the base, the drum core is bonded to the base while straddling the terminals. Further, the terminals are plated over the entire surface in order to perform soldering with the wiring board.

[0003]

In order to cure the adhesive, the inductor is heated during the manufacturing process. Further, when mounting on a wiring board, it is necessary to solder the terminals through a reflow tank, and in this case, the terminals are exposed to high heat. When high heat is applied to the inductor in this manner, the bonding strength between the drum core and the base is reduced, and the drum core may be peeled off from the base due to some external force during transportation.

The inventor of the present invention has studied the reduction in the adhesive strength of the drum core, and has found that one of the causes is as follows. That is, although the terminal is attached to the base, the terminal occupies a large proportion of the surface area of the base, and the drum core is adhered to the base while straddling the terminal. If high heat is applied to the inductor, the plating on the terminal surface will melt or peel off, which will cause a change in the state. is there.

In view of the above, it is conceivable to change the shapes of the base and the terminal so as to reduce the area occupied by the terminal with respect to the base. However, since such a change involves a change in the characteristics of the inductor, it is not easy because other components change. In addition, since both the base and the terminal are manufactured using a mold, the change of the mold is required, which takes time and is expensive.

The present invention has been made in view of such conventional problems, and provides a surface mount type inductor having a relatively simple structure and capable of improving the adhesive strength of a drum core. With the goal.

[0007]

In order to achieve the above object, a first aspect of the present invention provides a drum core having a winding,
A pair of terminals to which the windings are connected, wherein the drum core is bonded to an upper surface of the pair of terminals with an adhesive in a state of straddling the pair of terminals, and at least the drum core of the pair of terminals Is characterized in that the bonding surface region is in a non-plated state.

In the present invention, the drum core is bonded to the upper surface of the terminal so as to straddle the pair of terminals. In the pair of terminals, the region of the bonding surface with the drum core is in a non-plated state, and the bonding surface region is not plated. Therefore, even if high heat is applied to the inductor, no state change occurs due to the presence of the plating. Therefore, the drum core can be bonded to the pair of terminals with high strength.

According to a second aspect of the present invention, there is provided a drum core on which a winding is provided, a pair of terminals to which the winding is connected, and a ring core having a gap and surrounding the drum core. A structure in which the pair of terminals is bonded to the upper surfaces of the pair of terminals with an adhesive in a state of straddling the pair of terminals, and at least a bonding surface region of the pair of terminals with the drum core is in a non-plated state. .

According to the present invention, in addition to the configuration of the first aspect of the present invention, the provision of a ring core enables application to a large-sized electronic component. Also in this invention, since the bonding surface region of the pair of terminals with the drum core is in a non-plated state, the drum core can be bonded to the pair of terminals with high strength.

According to a third aspect of the present invention, there is provided a base made of an insulating material, a pair of terminals attached to the base in a positioned state, and a drum core provided with a winding connected to the pair of terminals, wherein the drum core comprises a pair. A structure that is bonded to the upper surfaces of the base and the pair of terminals with an adhesive in a state of straddling the terminals, wherein at least a bonding surface area between the pair of terminals and the drum core is in a non-plated state. I do.

In the present invention, the pair of terminals are attached to the base, and the drum core is bonded to the base so as to straddle the pair of terminals. In the pair of terminals, the bonding surface area with the drum core is in a non-plated state, and the bonding surface area is not plated. Therefore, even if high heat is applied to the inductor, a state change due to the presence of plating does not occur, and the drum core can be bonded to the base with high strength.

According to a fourth aspect of the present invention, there is provided a base made of an insulating material, a pair of terminals attached to the base in a positioned state, a drum core provided with a winding connected to the pair of terminals, and a gap. A ring core surrounding the periphery of the drum core, and the drum core and the ring core are bonded to the upper surfaces of the base and the pair of terminals with an adhesive in a state of straddling the pair of terminals. The bonding surface area is in a non-plated state.

According to the present invention, since the ring core is provided around the drum core, it can be applied to a large electronic component. Also in this invention, since the bonding surface area of the pair of terminals with the drum core is in a non-plated state, there is no change in state due to plating, and the drum core can be bonded to the base with high strength.

A fifth aspect of the present invention is the invention according to the second or fourth aspect, wherein the ring core is bonded around the drum core via an adhesive.

By bonding the ring core to the drum core in this way, the ring core can be fixed in a state where the ring core is positioned relatively to the drum core. Therefore, the gap between the ring core and the drum core can be reliably held, and the performance can be improved in addition to the actions and effects of the second and fourth aspects.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to embodiments shown in the drawings. In each embodiment, the same members are denoted by the same reference numerals and correspond to each other.

(First Embodiment) FIGS. 1 to 4 show a first embodiment of the present invention. As shown in FIG. 1, the surface mount type inductor 1 of this embodiment includes a base 2, a pair of terminals 3, 3, and a drum core 4 around which a winding 5 (see FIG. 2) is wound.

The base 2 is formed in a thin rectangular plate shape using an insulating material such as an insulating resin. On the upper surface of the base 2, there are formed terminal mounting portions 6, 6 to which the terminals 3, 3 are fitted, respectively, and positioning protrusions 7 for the drum core.

The terminal mounting portions 6 and 6 are located at a pair of opposite corners of the base 2 and have a planar rectangular shape lower than the upper surface of the base 2 by the thickness of the terminals 3 and 3. . A recess 9 is formed on the side surface of the base 2 at each of the terminal mounting portions 6 and 6 where the connecting piece 13 of the terminal 3 is fitted to prevent the terminal 3 from being displaced. Engagement projections 8, 8 that engage with the engagement holes 16 of the terminals 3 are formed on the upper surfaces of the terminal attachment portions 6, 6.

The positioning projection 7 protrudes from the upper surface of the base 2 so as to form an arc centered on the center of the base. Since the positioning protrusion 7 is provided so as to have a diameter including the terminal mounting portion 6 forming region, the positioning protrusion 7 is cut off in the terminal mounting portion 6 forming region.

An inner portion of the positioning protrusion 7 on the upper surface of the base 2 is provided with a core mounting portion 17 on which the drum core 4 is mounted.
It has become. One corner of the base 2 is a notch corner 10 cut out along the thickness direction of the base 2, and the wiring board 20 is formed based on the notch corner 10.
The direction of the inductor 1 in the soldering to (see FIG. 2) is set.

The pair of terminals 3 is entirely made of a thin plate of a conductive metal such as phosphor bronze.
And

The sandwiching portion 14 is formed in a U-shape in which the upper sandwiching piece 11 and the lower sandwiching piece 12 are continuously connected by the vertically extending connecting piece 13, and the interval between the upper and lower sandwiching pieces 11, 12 is the same as that of the base 2. The thickness is substantially equal to the thickness of the terminal mounting portion 6.
The terminals 3 and 3 are attached to the base 2 by the sandwiching portion 14 sandwiching the terminal attachment portion 6.

An engagement hole 16 is formed in the upper sandwiching piece 11 so that the engagement protrusion 8 of the base 2 can be engaged. Is fixed to the base 2. By the engagement of the engagement hole 16 and the fitting of the connecting piece 13 into the recess 9, the terminal 3 is securely fixed to the fixed position of the base 2, and does not shift. In addition, the lower holding piece 12 in the holding portion 14
Are exposed on the lower surface of the base 2 and are brought into conduction with a pattern (not shown) of the wiring board 20.

The binding portion 15 is formed on the upper holding piece 11 of the holding portion 14.
It is installed continuously. The binding portion 15 is directed from the upper sandwiching piece 11 to the continuous piece 13, that is, the drum core 4 on the base 2.
Upper sandwiching piece 11 to be bent at an acute angle away from
It is installed continuously. When the terminal 3 is attached to the base 2, the length of the binding portion 15 is set so that the tip of the binding portion 15 is located in the plane of the base 2. At the tip of the binding portion 15, a binding recess 15a cut out along the width direction of the plate is formed, and the lead portion 5a at the tip of the winding wire 5 is formed using the binding recess 15a as a guide. Is wound around the binding portion 15 (see FIG. 3).

When the terminals 3 and 3 having the sandwiching portion 14 and the binding portion 15 are attached to the base 2, the area occupied by the core mounting portion 17 becomes large as shown in FIG. Therefore, the contact area with the drum core 4 mounted on the core mounting portion 17 is increased.

The drum core 4 is formed of ferrite, which is an oxide magnetic material, and includes a reel 18 and a reel 1.
8 has flange portions 19, 19 integrally formed at both ends. The winding 5 is wound around the winding shaft 18 of the drum core 4. The lead 5a of the winding 5 wound around the winding shaft 18 of the drum core 4 is wound around the binding portion 15 of each of the terminals 3 and 3, and the winding 5 and the terminal 3 are soldered after the winding. , 3 are electrically connected.

The drum core 4 has a flange 19
Are fixed to the upper surface of the base 2 so as to straddle the terminals 3. That is, although the flange portion 19 abuts on the core mounting portion 17, a part of the terminals 3 and 3 intrudes into the core mounting portion 17 and the invading portion (the hatched portion in FIG. ) Is fixed to the base 2 so as to straddle.

To assemble such an inductor 1, first, the holding portion 14 is fitted into the terminal mounting portion 6,
Attach terminals 3 and 3 to base 2. Then, an adhesive (not shown) is applied on the core mounting portion 17. As the adhesive, an epoxy adhesive which is advantageous in terms of adhesive strength and electric characteristics is preferable. The adhesive is also applied to the terminals 3, 3 that have penetrated into the core mounting portion 17. Thereafter, one of the flange portions 19 is brought into contact with the core mounting portion 17 so as to straddle the terminals 3, 3, and the whole is heated to cure the adhesive, thereby fixing the drum core 4 to the base 2. Then, the winding 5 is applied to the drum core 4, and the lead 5 a is wound around the binding portion 15 and soldered to connect the winding 5 to the terminals 3.

As shown in FIG. 2, the assembled inductor 1 is mounted with the lower surface of the base 2 on a wiring board 20 and passed through a high-temperature reflow, so that the terminals 3 and 3 exposed from the base 2 are exposed. Is soldered to the pattern of the wiring board 20. Thus, the mounting of the inductor 1 on the wiring board 20 is performed.

In order to perform such soldering reliably and smoothly, the terminals 3 and 3 are previously plated with solder plating, tin plating or the like. In this embodiment, these platings are applied to portions of the pair of terminals 3, 3 excluding at least the area of the bonding surface with the drum core 4. Therefore, the bonding surface area of the terminals 3 and 3 with the drum core 4 is in a non-plated state. An example of the non-plating process is as follows. A frame (base material) is partially (eg, striped)
When performing a plating process, when punching into a terminal shape for the frame that formed the plated part and the non-plated part,
It can be manufactured by matching a stripe portion to a molding die. As a method of performing the striping plating, a method of applying a mask to a non-plated portion or a method of contacting a roller with a portion requiring plating can be considered.

More specifically, the hatched portion in FIG. 4 is a bonding surface area 21 with the drum core 4 located on the core mounting portion 17, and the bonding surface area 21 is plated. And the terminal base material is exposed. On the other hand, plating is applied to the terminal portions other than the dashed-line hatched portions (adhesion surface region 21). Since the bonding surface region 21 with the drum core 4 is in a non-plated state, even when heated during the curing of the adhesive or when high heat is applied during the soldering, it does not affect plating such as plating melting or plating peeling. The resulting state change does not occur in the bonding surface region 21. For this reason, in the bonding surface region 21, the drum core 4 can be bonded to the base 2 with high strength, and peeling due to a reduction in the bonding strength of the drum core 4 can be reliably prevented even with a simple structure.

In order to perform the above operation, it is preferable that both the upper and lower surfaces of the bonding surface region 21 of the terminals 3 and 3 are in a non-plated state. It may be plated. In this case, the lower surface of the bonding surface region 21 is plated, but the terminals 3, 3 are pressed by the drum core 4 in a state of being engaged with the engagement projections 8, so that no substantial problem occurs. It is.

Although the base material is exposed, rust is generated in the bonding surface area 21 with time, but by controlling the use period of the inductor 1 after manufacturing, mounting is performed before rust is generated. be able to.

In such an embodiment, the drum core 4
Since there is no occurrence of peeling due to a decrease in the adhesive strength, a reliable inductor can be obtained. Further, since the adhesive strength of the drum core 4 can be maintained even in contact with a high temperature, the present invention can be applied to soldering containing no lead. In the case of soldering which does not contain lead, the reflow temperature rises by 10 to 20 ° C. higher than usual, but since there is no plating in the bonding surface region 21 of the drum core 4, there is no state change caused by plating.

(Embodiment 2) FIGS. 5 to 8 show Embodiment 2 of the present invention. In the inductor 31 of this embodiment, a ring core 32 is added to the configuration of the first embodiment. This enables application to large electronic components. The ring core 32 is made of the same ferrite as the drum core 4 and has the same height as the drum core 4, but is formed into a ring shape having a diameter larger than the flange portion 19 of the drum core 4.

The ring core 32 has a gap G
The drum core 4 is placed on the base 2 so as to surround the drum core 4 (see FIG. 6). In this embodiment,
The inner diameter of the ring core 32 is equal to the outer diameter of the positioning projection 7 of the base 2. Therefore, the ring core 32 is placed on the base 2 while being positioned on the positioning projection 7. Also, at the time of mounting, the ring core 32 is
The base 2 is in contact with the base 2 so as to straddle the base 3.

To fix the ring core 32 on the base 2,
An adhesive (not shown) similar to the above is applied at regular intervals on the ring core mounting portion 33 (see FIG. 8) of the base 2, and after the ring core 32 is mounted, the adhesive is cured by heating. Do. Also, an adhesive 34 is poured at appropriate intervals also between the flange portion 19 of the drum core 4 and the ring core 32, and is heated and cured to bond the drum core 4 and the ring core 32. By bonding the drum core 4 and the ring core 32 with the adhesive 34 in this manner,
The gap G between them can be reliably maintained. As a result, the drum core 4 and the ring core 32 do not come into contact with each other, and variations in inductance do not occur.

In the above-described embodiment in which the ring core 32 is provided, as shown by the broken line hatching in FIG.
In this case, the bonding surface area 21 with the drum core 4 is not plated and is in a non-plated state. Thereby, the state of the bonding surface area 21 does not change, and the bonding strength of the drum core 4 can be increased.

In this embodiment, it is sufficient that at least the bonding surface area 21 of the terminals 3 and 3 with the drum core 4 is in a non-plated state, and the terminal portion corresponding to the ring core mounting portion 33 on which the ring core 32 is mounted is provided. , May be in a non-plated state, or may be in a plated state. In the latter case, there is a merit that the appearance is improved.

(Embodiment 3) FIG. 9 shows Embodiment 3 of the present invention. The inductor 41 according to this embodiment includes the drum core 4 in which the winding 5 is applied to the winding shaft portion 18 and a pair of terminals 3 and 3, and the base 2 according to the first and second embodiments is omitted. ing.

A concave portion 42 is formed in the lower flange portion 19 of the drum core 4, and the terminal 3 is bent along the concave portion 42 and the lower surface of the lower flange portion 19. Reference numeral 45 denotes a contact portion which is bent in this way and comes into contact with the flange portion 19. A rising portion 43 is formed on the outer peripheral portion of each of the terminals 3 and 3 along the side surface of the flange portion 19, and an inner portion of the rising portion 43 is an electrode portion 44 which is bent downward to protrude. . The electrode portion 44 is to be soldered to a pattern on the wiring board.

In this embodiment, the drum core 4 is bonded to the terminals 3 and 3 with an adhesive while straddling the pair of terminals 3 and 3. The adhesive is applied to the contact portion 45 and the rising portion 4
By applying between them, adhesion to the drum core 4 is performed. That is, the upper surface of the contact portion 45 and / or the upper surface of the rising portion 43 serve as a bonding surface region to be bonded to the drum core. A part (not shown) of the contact portion 45 and the rising portion 43 is set to a non-plating state where plating is not performed. This is because, for example, the upper surface of the contact portion 45 is not plated, or the rising portion 4
This can be done by setting the upper surface of 3 to a non-plated state, or setting a part of these to a non-plated state. Thus, by forming the non-plated portion, it is possible to reduce a change in the state of the bonding surface region when high-temperature heat is applied. Thereby, the adhesive strength of the drum core 4 can be improved.

(Fourth Embodiment) FIG. 10 shows a fourth embodiment. In this embodiment, a ring core 32 is provided in addition to the configuration of the third embodiment. Ring core 3
2 is bonded to the drum core 4 with a gap by applying an adhesive 34 to the flange 19 of the drum core 4. Thus, there is no variation in inductance.

Also in this embodiment, a portion (not shown) of the contact portion 45 and / or the rising portion 43 in the terminals 3 and 3 is in a non-plating state where plating is not performed. Thus, the change in the state of the bonding surface region when high-temperature heat is applied can be reduced, so that the bonding strength of the drum core 4 can be improved.

[0047]

According to the first aspect of the present invention, since the bonding surfaces of the pair of terminals with the drum core are in a non-plated state, the state of the drum core does not change even when high heat is applied. It can be bonded to a pair of terminals with high strength.

According to the second aspect of the present invention, the provision of the ring core makes it possible to apply the present invention to a large-sized electronic component, and furthermore, the bonding surface area of the pair of terminals with the drum core is in a non-plated state. Therefore, the drum core can be bonded to the pair of terminals with high strength.

According to the third aspect of the present invention, since the bonding surface area of the pair of terminals with the drum core is in a non-plated state, even if high heat is applied, the state does not change, and the drum core is connected to the base. With high strength.

According to the fourth aspect of the present invention, by providing the ring core, it is possible to apply the present invention to a large-sized electronic component, and furthermore, the bonding surface area of the pair of terminals with the drum core is in a non-plated state. Therefore, the drum core can be bonded to the base with high strength.

According to the fifth aspect of the invention, in addition to having the same effects as those of the second or fourth aspect, the gap between the ring core and the drum core can be reliably held, so that the performance can be improved. it can.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing Embodiment 1 of the present invention.

FIG. 2A is a perspective view showing an assembled state of the first embodiment;
FIG. 3 is a sectional view taken along line A.

FIG. 3 is a plan view showing an assembled state of the first embodiment.

FIG. 4 is a view showing a first embodiment by omitting a drum core.
FIG. 4 is a plan view showing a bonding surface region of FIG.

FIG. 5 is a sectional view taken along line BB of FIG. 6 in the embodiment.

FIG. 6 is a plan view of an assembled state according to the second embodiment.

FIG. 7 is a front view showing an assembled state of the second embodiment.

FIG. 8 is a plan view showing an adhesive surface area of the second embodiment by omitting a drum core and a ring core.

FIG. 9 is a sectional view of a third embodiment.

FIG. 10 is a sectional view of a fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inductor 2 Base 3 Terminal 4 Drum core 5 Winding 21 Adhesive surface area

Claims (5)

[Claims] 1. A drum core provided with a winding, and a pair of terminals to which the winding is connected, wherein the drum core is bonded to an upper surface of the pair of terminals with an adhesive while straddling the pair of terminals. A surface-mounted inductor, wherein at least the bonding surface area of the pair of terminals with the drum core is in a non-plated state. 2. A drum core provided with a winding, a pair of terminals to which the winding is connected, and a ring core having a gap and surrounding the drum core with a gap, wherein the drum core and the ring core straddle the pair of terminals. A surface-mounted inductor having a structure in which the pair of terminals are bonded to an upper surface of the pair of terminals by an adhesive in a state where the terminals are at least bonded to a drum core in a non-plated state. 3. A base made of an insulating material, a pair of terminals attached to the base in a positioned state, and a drum core provided with a winding connected to the pair of terminals, the drum core straddling the pair of terminals. A surface-mounted inductor having a structure adhered to an upper surface of the base and the pair of terminals by an adhesive in a state, wherein at least a bonding surface area of the pair of terminals with a drum core is in a non-plated state. . 4. A base made of an insulating material, a pair of terminals attached to the base in a positioned state, a drum core provided with a winding connected to the pair of terminals, and a periphery of the drum core having a gap. A surrounding ring core, wherein the drum core and the ring core are bonded to an upper surface of the base and the pair of terminals with an adhesive while straddling the pair of terminals, and at least a bonding surface area of the pair of terminals with the drum core is non-adhesive. A surface mount type inductor characterized by being in a plated state. 5. The ring core according to claim 2, wherein the ring core is bonded around the drum core via an adhesive.
Or the surface mount inductor according to 4.