CN113921224B

CN113921224B - SMD inductor

Info

Publication number: CN113921224B
Application number: CN202111060714.8A
Authority: CN
Inventors: 马坤林; 罗辉; 蓝增春
Original assignee: Xiamen Yike Electronic Co ltd
Current assignee: Xiamen Yike Electronic Co ltd
Priority date: 2021-09-10
Filing date: 2021-09-10
Publication date: 2023-12-12
Anticipated expiration: 2041-09-10
Also published as: CN113921224A

Abstract

The invention discloses an SMD inductor, which comprises a magnetic core, an inductance coil and pins, and is characterized in that: the lower extreme of pin is equipped with the connecting seat, and the connecting seat includes the metal cover body, and the top of the cover body is connected fixedly with the lower extreme of pin, is equipped with the metal bottom in the bottom of the cover body, and the edge of bottom and the inner wall sealing connection of the cover body are equipped with the inflow hole on the bottom, are equipped with the fly leaf in the cover body, are equipped with the elastic washer in the cover body, and the fly leaf top is the holding chamber, and the holding intracavity is filled with the hot melt thing, and the top of the cover body is equipped with the outflow hole. During mounting, after the bottom cover is contacted with solder paste at the welding point, the solder paste plugs the inflow hole on the bottom cover, so that the space below the movable plate is sealed, paraffin solid is melted by heating of the solder paste, the elastic gasket drives the movable plate to rise, negative pressure is formed in the cavity below the movable plate, part of solder paste at the welding point is extruded into the cover body from the inflow hole, welding between the connecting seat and the welding point is firmer and more reliable, and the situation that the inductor loosens after the PCB is long is avoided.

Description

SMD inductor

Technical Field

The invention relates to the technical field of patch inductors, in particular to an SMD inductor.

Background

With the rapid development of the electronic information industry, patch-type electronic components are being largely adopted, and a patch inductor is one of them.

Before the inductor is mounted, the solder paste softened at high temperature is coated (or printed) on the welding spot of the PCB, then the pins of the inductor are contacted with the solder paste and pressed against the welding spot, and the pins and the welding spot are fixed after the solder paste is cooled and solidified, so that the mounting of the inductor is completed.

The mounting mode only depends on the fact that the bottom surfaces of pins are welded and fixed with welding spots through soldering tin, the stability of welding is not very high, the soldering tin can be aged after long-time use, and in addition, the inductor is a component with large volume and weight, and the inductor is easy to fall off when the circuit board is impacted to vibrate, so that the mounting mode needs to be improved.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide an SMD inductor which has better connection stability after being attached and can not loosen or fall off after a long time.

In order to achieve the above purpose, the present invention provides the following technical solutions:

the utility model provides a SMD inductor, includes the magnetic core, winds the inductance coil on the magnetic core, overlaps the outside insulating lag of inductance coil to and a pair of pin, the upper end and the magnetic core connection of pin are fixed, the lower extreme of pin is provided with the connecting seat, the connecting seat is used for connecting the solder joint on pin and the PCB board fixedly, the connecting seat includes the metal cover body, the top of the cover body is connected fixedly with the lower extreme of pin, and the cover body middle part is the cavity, is provided with the metal bottom in the bottom of the cover body, the edge of bottom and the inner wall sealing connection of the cover body, the multiunit is used for supplying the inflow hole in the solder paste inflow cavity of multiunit on the bottom, the inside fly leaf that is provided with of cover, the edge of fly leaf and the inner wall laminating of the cover body, the fly leaf can be at the internal upper and lower activity of cover, be provided with annular elastic washer in the cover body, the elastic washer can compress and expand in upper and lower direction, the elastic washer sets up between bottom and fly leaf, there is the distance between the interior top of fly leaf and the cover body for the inner top and cover body, the inner cavity and the cavity of cover form, the cavity of compressing, the cavity is in the intercommunication state, the cavity is flowed out.

As a preferable scheme: the middle part of the bottom cover is provided with a lower convex part, the bottom surface of the lower convex part is higher than the bottom surface of the cover body, and the plurality of groups of inflow holes are arranged on the lower convex part.

As a preferable scheme: the inner side of the lower convex part is provided with a heat-insulating sealing cover, the sealing cover is tightly attached to the lower convex part, a hole site is formed in the sealing cover corresponding to each inflow hole, and the hole site is filled with hot-melt materials which seal the hole site.

As a preferable scheme: the edge of the bottom cover extends downwards to enable the side wall of the bottom cover to have a certain height, an outwards convex annular edge is arranged at the lower part of the edge of the bottom cover, the annular edge is in sealing connection with the inner wall of the cover body, and the bottom surface of the annular edge is lower than the bottom surface of the lower protruding part.

As a preferable scheme: an annular space is formed between the outer wall of the bottom cover and the inner wall of the cover body, and the elastic gasket is installed in the annular space.

As a preferable scheme: the elastic gasket is of an annular hollowed elastic net structure.

As a preferable scheme: the bottom edge of the cover body is provided with a convex annular flange.

As a preferable scheme: the outer ring area of the top surface of the cover body is provided with a downward inclined slope.

Compared with the prior art, the invention has the advantages that: this inductor is through setting up the connecting seat at the tip of pin, after the bottom of connecting seat contacts with the solder paste of solder joint department during the dress, the solder paste blocks up the inflow hole on the bottom lid for the space of fly leaf below is sealed, the heat of solder paste can heat the paraffin solid of holding intracavity, make paraffin solid melt become fluid, the flexible washer drive fly leaf rises, the atmospheric pressure in the cavity of fly leaf below becomes low and forms the negative pressure, partial solder paste of solder joint department is by being crowded into the cover from inflow hole department in, make the welding between connecting seat and the solder joint more firm reliable, the soldering tin is difficult for becoming flexible or drops, the condition that the inductor takes place the pine after avoiding the PCB board to take off for a long time.

Drawings

Fig. 1 is a sectional view of an inductor in the present embodiment;

fig. 2 is an enlarged view of a portion a in fig. 1;

fig. 3 is an enlarged view of a portion B in fig. 2.

Reference numerals indicate 1, magnetic core; 2. an inductance coil; 3. an insulating protective sleeve; 4. pins; 5. a connecting seat; 501. a cover body; 502. a receiving chamber; 503. a bottom cover; 504; sealing cover; 505; a movable plate; 506. an elastic washer; 507. a flange; 508. an outflow hole; 509. hole sites; 510. and flows into the hole.

Detailed Description

Referring to fig. 1, 2 and 3, an SMD inductor includes a magnetic core 1, an inductance coil 2 wound around the magnetic core 1, an insulation shield 3 sleeved outside the inductance coil 2, and a pair of pins 4, the upper ends of the pins 4 being fixedly connected with the magnetic core 1.

The lower extreme at pin 4 is provided with connecting seat 5, and connecting seat 5 is used for connecting pin 4 with the solder joint on the PCB board fixedly.

The connection seat 5 in this embodiment comprises a hollow metal cover 501. The top of cover body 501 is connected fixedly with the lower extreme of pin 4, and the cover body 501 middle part is the cavity, is provided with metal bottom 503 in the bottom of cover body 501, and the edge of bottom 503 and the inner wall sealing connection of cover body 501 have seted up multiunit and have been used for supplying the inflow hole 510 in the solder paste inflow cavity on bottom 503, are provided with fly leaf 505 in the inside of cover body 501, and the edge of fly leaf 505 is laminated with the inner wall of cover body 501 to guarantee the leakproofness between the edge of fly leaf 505 and the inner wall of cover body 501, fly leaf 505 can reciprocate in cover body 501.

The sealing property can be achieved by improving the adhesion degree of the movable plate 505 to the cover 501 or by applying a sealing grease between the edge of the movable plate 505 and the inner wall of the cover 501.

An annular elastic washer 506 is provided in the housing 501, the elastic washer 506 being compressible and expandable in the up-down direction, a degree portion of the elastic washer 506 being in contact with the top surface of the bottom cover 503, and a top portion of the elastic washer 506 being in contact with the bottom surface of the movable plate 505. There is a distance between the movable plate 505 and the inner top of the cover 501, so that a containing cavity 502 is formed between the movable plate 505 and the inner top of the cover 501, paraffin or other low-melting-point solid is filled in the containing cavity 502, an outflow hole 508 is arranged at the top of the cover 501, the outflow hole 508 is communicated with the containing cavity 502, and the elastic gasket 506 is pressed down by the movable plate 505 to be in a compressed state.

And printing or smearing softened solder paste on the welding spots on the PCB, wherein the solder paste on the welding spots is in a high-temperature state. And then the inductor can be mounted, when the inductor is mounted, the inductor is close to the welding point, the connecting seat 5 is contacted and pressed with the welding point, and the solder paste is waited for cooling and fixing, so that the mounting of the inductor is completed.

In the connecting seat 5 of the present embodiment, after the bottom cover 503 contacts with the solder paste at the solder joint, the solder paste plugs the inflow hole 510 on the bottom cover 503, so that the space under the movable plate 505 is sealed. Because the bottom cover 503 and the cover 501 are both made of metal materials and have good thermal conductivity, the heat of the solder paste can be quickly transferred to the bottom cover 503 and the cover 501, so that the temperature of the bottom cover 503 and the cover 501 is increased, and the paraffin solid in the accommodating cavity 502 can be heated after the temperature of the cover 501 is increased, so that the paraffin solid is melted to become fluid. The paraffin fluid flows out from the outflow hole 508, and at this time, the elastic force of the elastic washer 506 is released, and the elastic washer 506 expands upward, driving the movable plate 505 upward. After the movable plate 505 rises, the air pressure in the cavity below the movable plate becomes low to form negative pressure, and part of solder paste at the welding point is extruded into the cover body 501 from the inflow hole 510 under the action of external air pressure, so that the solder paste is attached to the bottom surface of the bottom cover 503, the inflow hole 510 and the top surface of the bottom cover 503, namely, the bottom surface and the inside of the connecting seat 5 are welded and fixed with the solder paste, and after the solder paste is cooled and solidified, the connecting seat 5 and the welding point are welded and fixed together. Compared with the traditional surface mounting mode, the connecting seat 5 adopted by the inductor can flow into the connecting seat 5 by solder paste, so that the welding between the connecting seat 5 and welding spots is more stable and reliable, soldering tin is less prone to loosening or falling off, and the situation that the inductor loosens after a long time of a PCB is avoided. In addition, the paraffin liquid flowing out from the outflow hole 508 flows downwards to cover the outer surface of the cover body 501 and the surface of the solder paste, and a protective layer is formed after the paraffin is cooled, so that the connection seat 5 and the solder can be prevented from being oxidized, and the connection reliability of the inductor and the welding point can be improved.

In order to promote the paraffin liquid to flow downwards, in this embodiment, the outer ring area of the top surface of the cover 501 is provided with a slope inclined downwards, so that the top surface of the cover 501 has a backflow effect, which is beneficial to the rapid downwards flow of the paraffin liquid.

In this embodiment, the middle part of the bottom cover 503 is provided with a lower protrusion, and the bottom surface of the lower protrusion is higher than the bottom surface of the cover 501, and the aforementioned multiple groups of inflow holes 510 are provided on the lower protrusion. The structure ensures that enough space is formed between the bottom surface of the bottom cover 503 and the welding spots, and the space allows solder paste below the bottom cover 503 to have a certain thickness, so that the welding structure between the bottom surface of the bottom cover 503 and the welding spots is ensured to have enough strength; in addition, the distance between the bottom cover 503 and the solder joint also facilitates solder paste being drawn into the housing 501.

In practice, there may be uneven application of solder paste at the solder joints, including insufficient application or excessive application of solder paste. When the solder paste is smeared too much, the connecting seat 5 can suck the solder paste, so that the excessive solder paste can be sealed in the cover body 501, and the connecting seat 5 can be prevented from extruding the excessive solder paste to the area around the welding spot during mounting, so that the excessive solder paste is prevented from being contacted with circuits or other components, and particularly, the PCB with higher integration level can be prevented.

When the amount of solder paste applied is insufficient, the solder paste may be spread out by being pressed by the bottom cover 503 during the mounting process, and the coverage area of the solder paste may be smaller than the bottom surface area of the lower convex portion of the bottom cover 503. Since the bottom cover 503 is provided with a plurality of groups of inflow holes 510, when the amount of solder paste is insufficient, the solder paste may not block all inflow holes 510, and thus the space under the movable plate 505 may not be completely sealed. When the movable plate 505 is lifted, the air pressure in the space below the movable plate cannot form an effective pressure difference with the external air pressure, so that solder paste cannot be effectively sucked into the cover 501, and the stability and reliability of final welding are affected.

In order to solve the above problem, in this embodiment, a heat-insulating sealing cover 504 is further disposed on the inner side of the lower protruding portion, the sealing cover 504 is closely attached to the lower protruding portion, and hole sites 509 are formed on the sealing cover 504 at positions corresponding to the respective inflow holes 510, that is, the hole sites 509 are aligned with the inflow holes 510 one by one. The hole 509 is filled with a hot melt, and the hole 509 is plugged by the hot melt. The hot melt in the hole 509 may also be paraffin.

When the bottom cover 503 contacts with the solder paste at the solder joint, the solder paste enters into the inflow hole 510 covered by the solder paste on the bottom cover 503, and at this time, the solder paste contacts with the hot melt in the hole 509 corresponding to the inflow hole 510, and the hot melt is heated and melted by the solder paste, so that the hole 509 is conducted, and the solder paste can flow into the cover 501 through the hole 509. The other solder-uncovered inflow holes 510 are not in contact with solder paste, the corresponding holes 509 are not in contact with solder paste, and heat from the bottom cover 503 is not transferred to the holes 509 because the sealing cover 504 is thermally insulated. The hot melt in the hole 509 is not heated by the solder paste and remains in a solid state, and the hole 509 remains in a sealed state. This allows only the solder-covered holes 509 of the sealing cap 504 to be conductive, while the solder-uncovered holes 509 remain sealed. Therefore, when the solder paste is not sufficiently smeared, the bottom cover 503 can be effectively sealed, so that the space below the movable plate 505 and the external space have enough pressure difference, and the solder paste is effectively sucked into the cover 501.

In this embodiment, the edge of the bottom cover 503 extends downward, so that the side wall of the bottom cover 503 has a certain height, and an outer convex annular edge is disposed at the lower part of the edge of the bottom cover 503, and the annular edge is in sealing connection with the inner wall of the cover 501, and the bottom surface of the annular edge is lower than the bottom surface of the lower convex part. An annular space is formed between the outer wall of the bottom cover 503 and the inner wall of the housing 501, and an elastic washer 506 is installed in the annular space. The structure can make the structure of the connecting seat 5 more compact, and is beneficial to reducing the volume of the connecting seat 5; and the contact area between the bottom cover 503 and the solder paste can be increased, so that the welding between the bottom cover 503 and the welding spot is more stable, and two purposes are achieved.

In this embodiment, a convex and annular flange 507 is provided at the bottom edge of the cover 501. This increases the contact area between the cover 501 and the solder paste.

In this embodiment, the elastic washer 506 is an annular hollow elastic net structure. The structure has good deformability and elastic recovery performance, and can effectively drive the movable plate 505 to rise; the hollowed-out structure can be used for solder paste to flow through, when the solder paste is sucked into the cover body 501, the solder paste flows to the edge part of the cover body 501 to fill the space below the movable plate 505, and when the solder paste flows to the elastic gasket 506, the solder paste flows through the hollowed-out structure and then contacts with the inner wall of the cover body 501, so that the cover body 501 and welding spots have better electric conductivity; and the hollowed-out structure can be used for attaching solder paste, and after the solder paste is cooled and solidified, a block-shaped structure is formed at the annular gasket, so that the bottom cover 503 and the cover body 501 can be connected more firmly.

The movable plate 505 is fixedly connected with the top of the elastic washer 506, so that the elastic washer 506 has a stabilizing effect on the movable plate 505, and the movable plate 505 is prevented from tilting when moving upwards.

The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above examples, and all technical solutions belonging to the concept of the present invention belong to the protection scope of the present invention. It should be noted that modifications and adaptations to the present invention may occur to one skilled in the art without departing from the principles of the present invention and are intended to be within the scope of the present invention.

Claims

1. The utility model provides an SMD inductor, includes the magnetic core, winds the inductance coil on the magnetic core, overlaps at the outside insulating lag of inductance coil to and a pair of pin, the upper end and the magnetic core of pin are connected fixedly, characterized by: the lower extreme of pin is provided with the connecting seat, the connecting seat is used for connecting the solder joint on pin and the PCB board fixedly, the connecting seat includes the metal cover body, the top of the cover body is connected fixedly with the lower extreme of pin, and the cover body middle part is the cavity, is provided with the metal bottom in the bottom of the cover body, the edge of bottom and the inner wall sealing connection of the cover body, the multiunit is used for supplying the inflow hole in the solder paste inflow cavity of seting up on the bottom, the inside fly leaf that is provided with of cover body, the edge of fly leaf is laminated with the inner wall of the cover body, the fly leaf is in the cover body upper and lower activity, be provided with annular elastic washer in the cover body, elastic washer compresses and expands in the upper and lower direction, elastic washer sets up between bottom and fly leaf, there is the distance between the interior top of fly leaf and cover body for form the holding chamber between the interior top of fly leaf and cover body, the holding intracavity is filled with the hot melt thing, the top of cover body is provided with the outflow hole, outflow hole and holding chamber intercommunication, elastic washer is in the compression state.

2. The SMD inductor of claim 1, wherein: the middle part of the bottom cover is provided with a lower convex part, the bottom surface of the lower convex part is higher than the bottom surface of the cover body, and the inflow hole is arranged on the lower convex part.

3. The SMD inductor of claim 2, wherein: the inner side of the lower convex part is provided with a heat-insulating sealing cover, the sealing cover is tightly attached to the lower convex part, a hole site is formed in the sealing cover corresponding to each inflow hole, and the hole site is filled with hot-melt materials which seal the hole site.

4. The SMD inductor of claim 1, wherein: the edge of the bottom cover extends downwards to enable the side wall of the bottom cover to have a certain height, an outwards convex annular edge is arranged at the lower part of the edge of the bottom cover, the annular edge is in sealing connection with the inner wall of the cover body, and the bottom surface of the annular edge is lower than the bottom surface of the lower protruding part.

5. The SMD inductor of claim 4, wherein: an annular space is formed between the outer wall of the bottom cover and the inner wall of the cover body, and the elastic gasket is installed in the annular space.

6. The SMD inductor of claim 5, wherein: the elastic gasket is of an annular hollowed elastic net structure.

7. The SMD inductor of claim 1, wherein: the bottom edge of the cover body is provided with a convex annular flange.

8. The SMD inductor of claim 1, wherein: the outer ring area of the top surface of the cover body is provided with a downward inclined slope.