CN118073065A - Power inductance bottom surface terminal and power inductance - Google Patents

Abstract

The invention discloses a power inductor bottom surface terminal and a power inductor, wherein the power inductor bottom surface terminal comprises a magnet, an inner electrode and a bonding pad; the magnet sets up the through-hole portion in the border position, and the inner electrode sets up in the magnet inside, and the through-hole portion is connected with the inner electrode and introduces the pad with the inner electrode, and the pad sets up in the magnet bottom. The bottom surface terminal of the power inductor avoids coil area damage caused by manufacturing a through hole in the magnet, and can enlarge the effective area of the electrode coil, thereby improving the utilization rate of the inner space of the magnet and improving the inductance of the power inductor.

Description

Power inductance bottom surface terminal and power inductance

Technical Field

The invention relates to the field of inductor manufacturing, in particular to a power inductor bottom surface terminal and a power inductor.

Background

Along with the requirements of electronic products such as mobile phones and the like, the electronic products are light, thin, short and small, and integrated with functions, under the condition of limited packaging space, the inductor size is also greatly reduced in face of the rapidly increased number of components, namely, the inductor internal coil is further miniaturized. However, the requirements of customers on the performance such as the inductance value of electronic components are also increasing, and the conventional bottom terminals need to break a large coil area, so that a high inductance value cannot be obtained. Therefore, the conventional full-terminal design and the bottom terminal design are combined, and the inductance of the power inductor is improved.

The existing inductance bottom terminal design generally adopts a mode of manufacturing a through hole in the magnet to connect an internal coil with an external electrode, and the effective area of part of the coil can be damaged when the internal space of the magnet is occupied by the through hole, so that higher inductance cannot be obtained.

Disclosure of Invention

The invention aims to solve the technical problem that the area of a coil broken by the existing bottom surface terminal is large, and provides a bottom surface terminal of a power inductor and the power inductor.

The technical problems of the invention are solved by the following technical scheme:

a power inductor bottom terminal comprises a magnet, an inner electrode and a bonding pad; the magnet is provided with a through hole part at the edge, the inner electrode is arranged in the magnet, the through hole part is connected with the inner electrode and leads the inner electrode into the bonding pad, and the bonding pad is arranged at the bottom of the magnet.

In some embodiments, the through hole portion includes a long through post and a short through post, and when the short through post is a lead-in end, the long through post is a lead-out end; when the short through column is an outgoing end, the long through column is an incoming end.

In some embodiments, the long through column may be disposed in a region of the magnet where S ₁ =a·b, where a is a width-direction single-sided margin of the magnet and B is a length-direction single-sided margin of the magnet.

In some embodiments, the short through posts may be disposed on the magnet in a region S ₂ =l·w (L-2·f) · (W-2·g), where L is the magnet length, W is the magnet width, F is the pad length in the length direction of the magnet, and G is the pad length in the width direction of the magnet.

In some embodiments, the cross-sectional area of the via portion is 0.5 to 5 times the product of the electrode linewidth C and the electrode linethickness K.

In some embodiments, the material of the via is silver, copper, and composites thereof.

In some embodiments, the exposed electrode of the through hole part is insulated by a resin coating process or a spraying process.

In some embodiments, the resin thickness of the resin coating process is 3 to 30 micrometers, and the resin material is an epoxy resin or an acrylic resin.

In some embodiments, the material of the pad is silver, copper, nickel, or tin.

The invention also provides a power inductor which comprises the power inductor bottom terminal.

Compared with the prior art, the invention has the beneficial effects that:

According to the power inductor bottom surface terminal and the power inductor, the through hole part is arranged at the edge of the magnet, the inner electrode is arranged in the magnet, the through hole part is connected with the inner electrode and leads the inner electrode into the bonding pad, coil area breakage caused by manufacturing the through hole in the magnet is avoided, the effective area of the electrode coil can be enlarged, the utilization rate of the inner space of the magnet is improved, and the inductance of the power inductor is improved.

Other advantages of embodiments of the present invention are further described below.

Drawings

FIG. 1 is a schematic diagram of a surface structure of a bottom terminal of a prior art power inductor;

FIG. 2 is a schematic side view of a prior art power inductor bottom terminal;

Fig. 3 is a schematic surface structure of a bottom terminal of a power inductor according to an embodiment of the present invention;

Fig. 4 is a schematic side view of a bottom terminal of a power inductor according to an embodiment of the present invention;

Fig. 5 is a schematic diagram of a limited area of a long through post 31 of a bottom terminal of a power inductor according to an embodiment of the present invention;

fig. 6 is a schematic diagram of a short-pass column 32 defining a bottom terminal of a power inductor according to an embodiment of the present invention;

Fig. 7 is a schematic diagram of a stacked structure of a power inductor according to an embodiment of the present invention;

fig. 8 is a schematic structural diagram of a power inductor according to an embodiment of the present invention.

The reference numerals are as follows:

1-magnet, 2-inner electrode, 3-through hole part, 31-long through column, 32-short through column, 4-bonding pad and 5-resin coating layer.

Detailed Description

The application will be further described with reference to the following drawings in conjunction with the preferred embodiments. It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other.

It should be noted that, in this embodiment, the terms of left, right, upper, lower, top, bottom, etc. are merely relative terms, or refer to the normal use state of the product, and should not be considered as limiting.

Fig. 1 and 2 are schematic structural diagrams of a bottom terminal of a power inductor according to the prior art. The traditional full-terminal design power inductor has the advantages that the effective area of the coil inside the magnet can be fully utilized, the bottom-surface terminal power inductor has the advantages that the size of the power inductor can be further reduced under the condition that the same inductance value and other performances of the traditional full-terminal can be kept, the trend of future market development is met, and the disadvantage is that the traditional bottom-surface terminal always needs to be broken and damaged by a larger coil area. The embodiment of the invention aims to combine the traditional full-terminal design and the bottom-surface terminal design, design the through column at the power inductor side-retaining position, fully utilize the product side-retaining size and design tolerance, so as to enlarge the effective area of the electrode coil and further improve the performance of the power inductor.

The embodiment of the invention discloses a power inductor bottom terminal, which comprises a magnet, an inner electrode and a bonding pad; the magnet sets up the through-hole portion in the border position, and the inner electrode sets up in the magnet inside, and the through-hole portion is connected with the inner electrode and introduces the pad with the inner electrode, and the pad sets up in the magnet bottom.

The through hole part comprises a long through column and a short through column, and when the short through column is a leading-in end, the long through column is a leading-out end; when the short through column is the leading-out end, the long through column is the leading-in end.

The long through column can be arranged in a region of the magnet with S ₁ =A.B, wherein A is the single side margin in the width direction of the magnet, and B is the single side margin in the length direction of the magnet. The short through posts may be disposed on the magnet in a region S ₂ =l·w (L-2·f) · (W-2·g), where L is the magnet length, W is the magnet width, F is the pad length in the length direction of the magnet, and G is the pad length in the width direction of the magnet. The cross-sectional area of the through hole portion is 0.5 to 5 times the product of the electrode line width C and the electrode line thickness K.

The material of the through hole part is silver, copper and a compound thereof, the exposed electrode of the through hole part is insulated by adopting a resin coating process or a spraying process, the thickness of the resin coating process is 3-30 microns, the resin material is epoxy resin or acrylic resin, and the material of the bonding pad is silver, copper, nickel or tin.

Example 1:

The embodiment shows a power inductor bottom terminal, as shown in fig. 3 and 4, comprising a magnet 1, an inner electrode 2 and a bonding pad 4; the magnet 1 is provided with a through hole part 3 at an edge position, the inner electrode 2 is arranged inside the magnet 1, the through hole part 3 is connected with the inner electrode 2 and leads the inner electrode 2 into a bonding pad 4, and the bonding pad 4 is arranged at the bottom of the magnet 1.

The magnet 1 is made of soft magnetic materials such as ferrosilicon chromium, ferrosilicon aluminum, ferronickel and the like or composite soft magnetic materials thereof; the internal electrode 2 is made of a conductive material with high conductivity such as silver or copper; the bonding pad 4 is usually silver layer, copper layer, nickel layer, tin layer.

The through hole part 3 comprises a bottom through column, which is divided into a long through column 31 and a short through column 32, and when the short through column 32 is a leading-in end, the long through column 31 is a leading-out end; when the short through column 32 is the lead-out end, the long through column 31 is the lead-in end. One of the long through columns 31 and the short through columns 32 is used as a leading-in end, the other one is used as a leading-out end, the function of conducting the internal coil is achieved, a part of coil effective area of the long through column 31 in the past needs to be folded and damaged to be used as a reserved space position for the column, and the effective area of the magnetic core can be folded and damaged in this way, so that inductance is low. The product under the same size condition can effectively improve the sensing quantity of the product by about 20% under the condition that the effective area of the coil is not damaged by utilizing the long through column 31 with the reserved edge design.

As shown in FIGS. 5 and 6, the power inductor of the present example was designed such that the width of the magnet 1 was W μm, the length was L μm, the width-wise one-sided margin was A μm, the length-wise one-sided margin was B μm, the electrode line width was C μm, the electrode line thickness was K μm, the width of the electrode inner ring was D μm (2/3.C. Ltoreq.D < W-2.C), the length of the electrode inner ring was E μm (2/3.C. Ltoreq.E < L-2.C), the length of the pad in the length direction of the magnet was F μm, and the length of the pad in the width direction of the magnet was G μm.

In the bottom surface terminal power inductance device of the embodiment, a bottom surface long through column 31 is arranged at a product edge position, and the area where the long through column 31 can exist is limited to be S1=A.Bμm2, wherein A is more than or equal to 50 μm and less than or equal to W-D-2.Cμm, and B is more than or equal to 50 μm and less than or equal to L-E-2.Cμm; the short via post 32 may be defined to exist in a region having an area s2=l·w- (L-2·f) · (W-2·g) μm2, where L/10 μm is less than L/2 μm, W/10 μm is less than G is less than W/2 μm, and it is satisfied that the long via post 31 and the short via post 32 are not at the same position.

The cross section of the bottom through column can be circular, fan-shaped, arbitrary N polygon (N is more than or equal to 3), irregular graph or the like, and the cross section area is 0.5 to 5 times of the product of the electrode line width C and the electrode line thickness K. From the perspective of calculus, N (N is more than or equal to 1) infinitely small holes can be prepared and connected together, the cross section shape of the infinitely small holes can be any shape, and the through column can be designed for meeting the condition that the cross section area is 0.5 to 5 times of the product of the electrode line width C and the electrode line thickness K, preventing the product from fusing and opening, and further fully utilizing the edge-reserved position to effectively promote miniaturization of the product.

The number of the bottom through columns of the long through columns 31 and the short through columns 32 is limited to X (X is more than or equal to 1), and when X is more than 1, the bottom through columns are used as the leading-out ends/leading-in ends; when the margin of a certain large-inductance small-size power inductor (1 uH) product is smaller, two or more small holes can be formed to serve as through columns, the distance between the through columns and the inner electrode coil is 10-60 mu m, and the through columns are prepared by laminating high-precision laminating equipment, so that the product is prevented from being opened.

The long through-posts 31 and the short through-posts 32 are defined by silver/copper and their composites. The bottom through-pillar material is defined as silver/copper or a composite thereof: the three metals with the best conductivity are silver, copper and gold. Silver belongs to noble metal, the cost is high, and silver ions migrate (silver ions move from high potential to low potential) under the action of hydroxide radicals (existing in a solvent) and an electric field so as to cause short circuit of products; copper is relatively cheap, the product cost can be reduced, copper is stable, and migration phenomenon does not occur.

The exposed electrode parts of the long through posts 31 and the short through posts 32 are limited by a resin coating process to form a resin coating layer 5, and in other embodiments, the resin coating layer can be insulated by a spraying process. The resin thickness of the resin coating layer 5 is 3-30 μm, and the resin material is epoxy resin or acrylic resin, etc. The exposed electrode is required to be insulated, so that the creeping plating during electroplating is prevented, and the product size is increased. The resin coating process or the spraying process is adopted because the insulation treatment is made as thin as possible, the corrosion-resistant reliability of the product is ensured, and the leakage protection effect is achieved.

Example 2:

the power inductor adopting the bottom terminal of the power inductor in the embodiment 1 is manufactured by the following steps:

S1: mixing ferroalloy powder (FeSiCr) with organic matters to form slurry, casting on a PET (polyethylene terephthalate) film to form a green belt, and cutting the green belt into tablets with the size of 152 mm;

S2: forming a bonding pad material sheet a, an inner electrode material sheet b, an inner electrode material sheet c, an inner electrode material sheet d, an inner electrode material sheet e, an inner electrode material sheet f and an inner electrode material sheet g on the upper surface of the material sheet by using a screen printing technology through laser perforation;

S3: laminating the printed material sheet and the substrate h in the sequence (a, b, c, d, e, f, g and h) shown in figure 7, and then increasing the product magnet density by dry pressing to obtain good product performance;

S4: cutting the pressed green stock obtained in the step S3 into green stock with the required size;

S5: performing heat treatment on the green embryo obtained in the step S5, namely decomposing and removing organic matters in the green embryo and obtaining more compact magnet performance;

s6: carrying out an electrophoretic resin coating process or a spraying process on six surfaces of the product obtained in the step S5, wherein the thickness of a resin layer is 3-30 mu m;

s7: removing the resin layer at the bonding pad position by a laser etching mode;

S8: electroplating a copper layer, a nickel layer and a tin layer on the surface of the bonding pad, so that the bonding pad is convenient to mount;

As shown in fig. 8, the bonding pad a on the upper surface of the final formed single power inductor is formed by stacking an inner electrode layer b, an inner electrode layer c, an inner electrode layer d, an inner electrode layer e, an inner electrode layer f and an inner electrode layer g from top to bottom, and the bottom surface is a substrate h, wherein a long through pillar 31 and a short through pillar 32 are designed at the side-reserved position as described in the embodiment 1.

When the circuit is formed by taking the short through column 32 as a leading-in end, the long through column 31 is taken as a leading-out end, and the internal electrode coil is communicated to a bonding pad at the bottom; while the short through-column 32 is the outlet end, the long through-column 31 is the inlet end.

As shown in table 1, compared with the inductor designed by the conventional bottom terminal, the power inductor of the embodiment has the advantages that through columns are designed by utilizing the reserved edge positions of the power inductor coil, so that the utilization rate of the internal space of the magnet is improved, the inductance of the magnet can be improved by more than 20%, and the smaller the size, the more the improvement ratio.

TABLE 1

The foregoing is a further detailed description of the invention in connection with the preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described. It will be apparent to those skilled in the art that several equivalent substitutions and obvious modifications can be made without departing from the spirit of the invention, and the same should be considered to be within the scope of the invention. In the description of the present specification, reference to the terms "one embodiment," "some embodiments," "preferred embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Those skilled in the art may combine and combine the features of the different embodiments or examples described in this specification and of the different embodiments or examples without contradiction. Although embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the scope of the invention as defined by the appended claims.

Claims (10)

1. The power inductor bottom terminal is characterized by comprising a magnet, an inner electrode and a bonding pad; the magnet is provided with a through hole part at the edge, the inner electrode is arranged in the magnet, the through hole part is connected with the inner electrode and leads the inner electrode into the bonding pad, and the bonding pad is arranged at the bottom of the magnet.

2. The power inductor bottom terminal as claimed in claim 1, wherein the through hole portion includes a long through post and a short through post, the long through post being a lead-out terminal when the short through post is a lead-in terminal; when the short through column is an outgoing end, the long through column is an incoming end.

3. The power inductor bottom terminal as claimed in claim 2, wherein the long through-posts are disposed in a region of the magnet where S ₁ =a·b, where a is a width-direction single-sided margin of the magnet and B is a length-direction single-sided margin of the magnet.

4. The power inductor bottom terminal as claimed in claim 1, wherein the short via is provided in a region S ₂ = L-W (L-2-F) S (W-2-G) on the magnet, where L is the magnet length, W is the magnet width, F is a pad length in a length direction of the magnet, and G is a pad length in a width direction of the magnet.

5. The power inductor bottom terminal as claimed in claim 4, wherein the cross-sectional area of the through hole portion is 0.5 to 5 times the product of the electrode line width C and the electrode line thickness K.

6. The power inductor bottom terminal as claimed in claim 5, wherein the material of the via portion is silver, copper or a combination thereof.

7. The power inductor bottom terminal as claimed in claim 6, wherein the exposed electrode of the through hole portion is insulated by a resin coating process or a spraying process.

8. The power inductor bottom terminal as claimed in claim 7, wherein the resin thickness of the resin coating process is 3 to 30 μm, and the resin material is epoxy or acrylic.

9. The power inductor bottom terminal of claim 1, wherein the pad material is silver, copper, nickel or tin.

10. A power inductor comprising a power inductor bottom terminal according to any one of claims 1 to 9.