阅读说明：本技术 多层金属膜以及电感器部件 (Multilayer metal film and inductor component ) 是由 笹岛菜美子 今枝大树 大门正美 大谷慎士 须永友博 吉冈由雅 于 2020-02-25 设计创作，主要内容包括：本发明提供能够缓和内部应力的蓄积的多层金属膜。电感器部件具备基体、配置在基体内的电感器、以及与设置在基体中的电感器电连接的作为布线的外部端子,外部端子具有与基体接触且具有导电性的第一金属膜、配置在相对于第一金属膜与基体相反侧且具有耐焊料腐蚀性的第二金属膜、以及设置在第一金属膜与第二金属膜之间的催化剂层,第一金属膜在催化剂层侧具有孔部。(The invention provides a multilayer metal film capable of relieving accumulation of internal stress. The inductor component includes a base, an inductor disposed in the base, and an external terminal as a wiring electrically connected to the inductor disposed in the base, the external terminal having a first metal film in contact with the base and having conductivity, a second metal film disposed on a side opposite to the base with respect to the first metal film and having solder corrosion resistance, and a catalyst layer disposed between the first metal film and the second metal film, the first metal film having a hole on a catalyst layer side.)

1. A multilayer metal film which is a metal film disposed on a substrate having insulating properties, the multilayer metal film comprising:

a first metal film in contact with the substrate and having conductivity;

a second metal film that covers the first metal film from the opposite side of the substrate to the first metal film and has solder corrosion resistance; and

a catalyst layer disposed between the first metal film and the second metal film,

the first metal film has a hole on the catalyst layer side.

2. The multilayer metal film of claim 1,

the first metal film has a cavity in the hole.

3. The multilayer metal film according to claim 1 or 2,

the hole of the first metal film is present in a range from a first main surface of the first metal film on the catalyst layer side to a film thickness of 1/4 or less of the first metal film.

4. The multilayer metal film according to any one of claims 1 to 3,

the size of the hole of the first metal film is 0.5 μm or less.

5. The multilayer metal film according to any one of claims 1 to 4,

the first metal film and the second metal film are electrically connected.

6. The multilayer metal film according to any one of claims 1 to 5,

the hardness of the first metal film is smaller than that of the second metal film.

7. The multilayer metal film according to any one of claims 1 to 6,

the substrate has a magnetic resin layer containing a resin and a metal magnetic powder contained in the resin,

the first metal film is in contact with the magnetic resin layer.

8. The multilayer metal film according to any one of claims 1 to 7,

the second metal film further has a third metal film thereon, and the third metal film has solder wettability.

9. The multilayer metal film according to any one of claims 1 to 8,

the first metal film contains Cu.

10. The multilayer metal film according to any one of claims 1 to 9,

the second metal film contains Ni.

11. The multilayer metal film according to any one of claims 1 to 10,

the catalyst layer contains Pd.

12. An inductor component is provided with:

a substrate;

the multilayer metal film of any one of claims 1 to 11; and

an inductor element disposed in the substrate,

the multilayer metal film is an external terminal exposed from the base and electrically connected to the inductor element.

Technical Field

The invention relates to a multilayer metal film and an inductor component.

Background

Conventionally, in an electronic component such as an inductor component, a plurality of metal films in which metal films are laminated have been used for internal electrodes constituting an electric element and external terminals serving as terminals of the electric element. For example, an inductor component described in japanese patent application laid-open No. 2014-13815 (patent document 1) includes: the magnetic circuit includes a substrate, spiral wirings provided on both surfaces of the substrate, a magnetic layer covering the spiral wirings, external terminals provided on a surface of the magnetic layer, and lead-out wirings electrically connecting the spiral wirings and the external terminals. The spiral wiring is a multilayer metal film composed of a Cu foundation layer formed on a substrate by an electroless plating step and two Cu electrolytic plating layers formed on the foundation layer by two times of electrolytic plating. The external terminals are formed by sputtering or screen printing before singulation, and are plated after singulation.

Patent document 1: japanese patent laid-open No. 2014-13815

In the multilayer metal film, the stacked metal films are closely adhered to each other by chemical or physical bonding force on the main surfaces thereof. Here, although thermal, electrical, and physical forces are applied to the electronic component during manufacturing, mounting, use, and the like, the forces may become internal stresses in the electronic component and accumulate, and peeling may occur between the metal films of the multilayer metal film. In the future, if further miniaturization of electronic parts is required and miniaturization and thinning of multilayer metal films are advanced, there is a possibility that the above-described peeling may occur even under manufacturing, mounting, and use conditions which have not been problematic in the past.

Disclosure of Invention

Accordingly, the present disclosure provides a multilayer metal film capable of alleviating accumulation of internal stress and an inductor component including the multilayer metal film.

In order to solve the above problem, a multilayer metal film as one embodiment of the present disclosure is a metal film disposed on a substrate having insulating properties, the multilayer metal film including:

a first metal film in contact with the substrate and having conductivity;

a second metal film that covers the first metal film from the opposite side of the substrate to the first metal film and has solder corrosion resistance; and

a catalyst layer disposed between the first metal film and the second metal film,

the first metal film has a hole on the catalyst layer side.

According to the above aspect, since the first metal film has the hole portion on the catalyst layer side, the internal stress accumulated in the multilayer metal film can be relaxed by the hole portion. The catalyst layer is a layer containing a metal that promotes deposition of the second metal film on the upper layer side. For example, in the case where the second metal film is a film containing Ni, if a layer containing Pd or the like that promotes oxidation of a reducing agent in a plating solution at the time of plating Ni is disposed between the first metal film and the second metal film, the deposition of the second metal film can be promoted by electroless plating treatment using the layer containing Pd or the like as a catalyst, and this layer becomes a catalyst layer.

In one embodiment, the first metal film has a cavity in the hole.

According to the above embodiment, it is possible to suppress a decrease in the purity of the first metal film due to impurities mixed into the holes of the first metal film.

In one embodiment, the hole of the first metal film is present in a range from a first main surface of the first metal film on the catalyst layer side to a film thickness of 1/4 or less of the first metal film.

According to the above embodiment, the area of the first metal film where the hole is present can be reduced, and the strength of the first metal film can be ensured.

In one embodiment, the size of the hole of the first metal film is 0.5 μm or less.

According to the above embodiment, the function and reliability of the multilayer metal film including the first metal film and the second metal film can be ensured.

In one embodiment, the first metal film and the second metal film are electrically conductive.

According to the above embodiment, the function and reliability of the multilayer metal film including the first metal film and the second metal film can be ensured.

In one embodiment, the hardness of the first metal film is smaller than the hardness of the second metal film.

According to the above embodiment, the accumulation of internal stress can be further alleviated by the first metal film being softer than the second metal film.

In addition, in one embodiment,

the substrate has a magnetic resin layer containing a resin and a metal magnetic powder contained in the resin,

the first metal film is in contact with the magnetic resin layer.

According to the above embodiment, the first metal film can be deposited by utilizing the conductivity or substitution reaction of the metal magnetic powder. In addition, the first metal film is strongly bonded to the metal magnetic powder, and the adhesion force between the substrate and the first metal film can be improved.

In one embodiment, the second metal film further includes a third metal film having solder wettability.

According to the above embodiment, the solder wettability of the multilayer metal film can be improved.

In one embodiment, the first metal film contains Cu.

According to the above embodiment, the conductivity of the multilayer metal film can be ensured at low cost. In addition, since the hardness of the first metal film can be reduced, the accumulation of internal stress in the multilayer metal film can be alleviated.

In one embodiment, the second metal film contains Ni.

According to the above embodiment, the solder corrosion resistance of the multilayer metal film can be easily improved.

In one embodiment, the catalyst layer contains Pd.

According to the above embodiment, the catalyst layer can be easily configured.

In one embodiment, an inductor component includes:

a substrate;

the above multilayer metal film; and

an inductor element disposed within the substrate,

the multilayer metal film is an external terminal exposed from the base and electrically connected to the inductor element.

According to the above embodiment, the inductor component can be provided in which the accumulation of internal stress in the external terminal is alleviated.

According to the multilayer metal film and the inductor component which are one embodiment of the present disclosure, accumulation of internal stress can be alleviated.

Drawings

Fig. 1A is a perspective plan view showing a first embodiment of an inductor component.

FIG. 1B is a cross-sectional view A-A of FIG. 1A.

Fig. 2 is an enlarged view of a portion of fig. 1B.

Fig. 3A is an explanatory diagram for explaining a method of manufacturing the inductor component.

Fig. 3B is an explanatory diagram for explaining a method of manufacturing the inductor component.

Fig. 3C is an explanatory diagram for explaining a method of manufacturing the inductor component.

Fig. 3D is an explanatory diagram for explaining a method of manufacturing the inductor component.

Fig. 4A is an image of a scanning electron microscope of the first embodiment of the inductor component.

Fig. 4B is an enlarged view of the external terminal.

Fig. 5 is an image of a scanning electron microscope of a second embodiment of an inductor component.

Description of reference numerals: 1 … inductor component; 2a … first inductor element; 2B … second inductor element; 10 … a substrate; 101 … first edge; 102 … second edge; 10a … first major face; 10b … first side; 10c … second side; 11 … a first magnetic layer; 12 … second magnetic layer; 21 … a first spiral wiring; 22 … second spiral wiring; 31 … first columnar wiring; 32 … second pillar wiring; 33 … third columnar wiring; 34 … fourth columnar wiring; 41 … first external terminal (multilayer metal film); 410 … a multilayer metal film; 411 … first metal film; 411a … aperture; 411b … first major face; 412 … a second metal film; 413 … a third metal film; 415 … catalyst layer; 415a … base; 415b … convex portions; 42 … second external terminal (multilayer metal film); 43 … third external terminal (multilayer metal film); 44 … fourth external terminal (multilayer metal film); 50 … insulating film; 61 … an insulating layer; 100 … mother substrates; 135 … resin; 136 … metal magnetic powder; a … (height of the protrusions); b … (aperture) range; t … (base) film thickness; t1 … (of the first metal film) film thickness; t2 … (of the second metal film) film thickness.

Detailed Description

Hereinafter, an inductor component as one embodiment of the present disclosure will be described in detail with reference to the illustrated embodiments. In addition, the drawings include a part of schematic views, and there are cases where actual sizes and ratios are not reflected.

(first embodiment)

(Structure)

Fig. 1A is a perspective plan view showing a first embodiment of an inductor component. FIG. 1B is a cross-sectional view A-A of FIG. 1A. Fig. 2 is an enlarged view of a portion of fig. 1B.

The inductor component 1 is a surface-mount electronic component mounted on a circuit board mounted on an electronic device such as a personal computer, a DVD player, a digital camera, a TV, a mobile phone, and an automotive electronic device, for example. However, the inductor component 1 may be a substrate-embedded electronic component instead of a surface-mounted electronic component. The inductor component 1 is, for example, a component having a rectangular parallelepiped shape as a whole. However, the shape of the inductor component 1 is not particularly limited, and may be a cylindrical shape, a polygonal columnar shape, a tapered trapezoidal shape, or a polygonal tapered trapezoidal shape.

As shown in fig. 1A and 1B, the inductor component 1 includes: the inductor includes an insulating substrate 10, a first inductor element 2A and a second inductor element 2B arranged in the substrate 10, a first columnar wiring 31, a second columnar wiring 32, a third columnar wiring 33, and a fourth columnar wiring 34 embedded in the substrate 10 and having end faces exposed from a rectangular first main surface 10a of the substrate 10, a first external terminal 41, a second external terminal 42, a third external terminal 43, and a fourth external terminal 44 arranged on the first main surface 10a of the substrate 10, and an insulating film 50 provided on the first main surface 10a of the substrate 10. In the figure, a direction parallel to the thickness of the inductor component 1 is a Z direction, a positive Z direction is an upper side, and a negative Z direction is a lower side. In a plane orthogonal to the Z direction, a direction parallel to the length of the inductor component 1 on the long side is defined as an X direction, and a direction parallel to the width of the inductor component 1 on the short side is defined as a Y direction.

The substrate 10 includes an insulating layer 61, a first magnetic layer 11 disposed on a lower surface 61a of the insulating layer 61, and a second magnetic layer 12 disposed on an upper surface 61b of the insulating layer 61. The first main surface 10a of the substrate 10 corresponds to the upper surface of the second magnetic layer 12. The substrate 10 has a 3-layer structure of the insulating layer 61, the first magnetic layer 11, and the second magnetic layer 12, but may have any one of a 1-layer structure of only the magnetic layer, a 2-layer structure of only the magnetic layer and the insulating layer, and a 4-layer or more structure including a plurality of magnetic layers and insulating layers.

The insulating layer 61 has an insulating property and has a layer shape with a rectangular main surface, and the thickness of the insulating layer 61 is, for example, 10 μm or more and 100 μm or less. From the viewpoint of height reduction, the insulating layer 61 is preferably an insulating resin layer such as an epoxy resin or a polyimide resin that does not contain a base material such as glass cloth, but may be a sintered body layer made of a magnetic material such as a ferrite such as a NiZn-based or MnZn-based ferrite, or a non-magnetic material such as alumina or glass, or may be a resin substrate layer containing a base material such as a glass epoxy resin. In addition, when the insulating layer 61 is a sintered body layer, the strength and flatness of the insulating layer 61 can be ensured, and the workability of the laminate on the insulating layer 61 can be improved. In the case where the insulating layer 61 is a sintered body layer, polishing is preferably performed from the viewpoint of height reduction, and particularly, polishing from the lower side where there is no laminate is preferable.

The first magnetic layer 11 and the second magnetic layer 12 have high magnetic permeability, are in the form of layers having rectangular main surfaces, and include a resin 135 and a metal magnetic powder 136 contained in the resin 135. The resin 135 is an organic insulating material made of, for example, epoxy resin, bismaleimide, liquid crystal polymer, polyimide, or the like. The metal magnetic powder 136 is a metal material having magnetic properties, such as a FeSi alloy such as fesicricr, a FeCo alloy, an Fe alloy such as NiFe, or an amorphous alloy thereof. The average particle diameter of the metal magnetic powder 136 is, for example, 0.1 μm or more and 5 μm or less. In the manufacturing stage of the inductor component 1, the average particle diameter of the metal magnetic powder 136 can be calculated as a particle diameter corresponding to 50% of the integrated value in the particle size distribution obtained by the laser diffraction/scattering method (so-called D50). The content ratio of the metal magnetic powder 136 is preferably 20 Vol% or more and 70 Vol% or less with respect to the entire magnetic layer. When the average particle diameter of the metal magnetic powder 136 is 5 μm or less, the dc bias characteristic is further improved, and the iron loss at high frequencies can be reduced by the fine powder. In addition, a magnetic powder of a ferrite such as NiZn or MnZn ferrite may be used instead of the metal magnetic powder.

The first inductor element 2A and the second inductor element 2B include a first spiral wiring 21 and a second spiral wiring 22 arranged in parallel with the first main surface 10a of the base 10. Thereby, the first inductor element 2A and the second inductor element 2B can be configured in the direction parallel to the first main surface 10a, and the height of the inductor component 1 can be reduced. The first spiral wiring 21 and the second spiral wiring 22 are disposed on the same plane in the base 10. Specifically, the first spiral wiring 21 and the second spiral wiring 22 are formed on the upper side of the insulating layer 61, in other words, only on the upper surface 61b of the insulating layer 61, and are covered with the second magnetic layer 12.

The first and second spiral wirings 21 and 22 are wound in a planar shape. Specifically, the first and second spiral wirings 21 and 22 are arc-shaped in a semi-elliptical shape when viewed from the Z direction. That is, the first and second spiral wirings 21 and 22 are curved wirings wound around approximately half of a circumference. The first and second spiral wirings 21 and 22 include straight portions in the middle. In the present application, the term "spiral" of the spiral wiring means a curved shape wound in a plane shape including a spiral shape, and includes a curved shape having 1 turn or less such as the first spiral wiring 21 and the second spiral wiring 22, and the curved shape may include a partial linear portion.

The thicknesses of the first and second spiral wirings 21 and 22 are preferably 40 μm or more and 120 μm or less, for example. As an example of the first and second spiral wirings 21 and 22, the thickness was 45 μm, the wiring width was 40 μm, and the inter-wiring space was 10 μm. In view of ensuring insulation, the space between the wirings is preferably 3 μm or more and 20 μm or less.

The first and second spiral wirings 21 and 22 are made of a conductive material, for example, a low-resistance metal material such as Cu, Ag, or Au. In the present embodiment, the inductor component 1 includes the first and second spiral wirings 21 and 22 of only one layer, and thus the height of the inductor component 1 can be reduced. The first and second spiral wirings 21 and 22 may be a multilayer metal film, and may have a structure in which a conductive layer of Cu, Ag, or the like is formed on a base layer of Cu, Ti, or the like formed by electroless plating, for example.

The first spiral wiring 21 is electrically connected to the first columnar wiring 31 and the second columnar wiring 32 having the first end and the second end located outside, respectively, and has a curved shape that draws an arc from the first columnar wiring 31 and the second columnar wiring 32 toward the center of the inductor component 1. In addition, the first spiral wiring 21 has pad portions having a line width larger than that of the spiral-shaped portion at both ends thereof, and is directly connected to the first and second pillar wirings 31 and 32 at the pad portions.

Similarly, the second spiral wiring 22 is electrically connected to the third columnar wiring 33 and the fourth columnar wiring 34 having the first end and the second end located outside, respectively, and is curved so as to draw an arc from the third columnar wiring 33 and the fourth columnar wiring 34 toward the center of the inductor component 1.

Here, in each of the first and second spiral wirings 21 and 22, a range surrounded by a curve drawn by the first and second spiral wirings 21 and 22 and a straight line connecting both ends of the first and second spiral wirings 21 and 22 is defined as an inner diameter portion. At this time, when viewed from the Z direction, the first and second spiral wirings 21 and 22 do not overlap each other at their inner diameter portions, and the first and second spiral wirings 21 and 22 are separated from each other.

The wirings further extend from the positions of connection of the first and second spiral wirings 21 and 22 to the first to fourth columnar wirings 31 to 34 in the direction parallel to the X direction and in the direction outside the inductor component 1, and the wirings are exposed outside the inductor component 1. In other words, the first and second spiral wirings 21 and 22 have an exposed portion 200 exposed to the outside from a side surface (a surface parallel to the YZ plane) parallel to the lamination direction of the inductor component 1.

The wiring is formed in the shape of the first and second spiral wirings 21 and 22 in the manufacturing process of the inductor component 1, and then connected to the power supply wiring when electrolytic plating is additionally performed. In the state of the inductor substrate before the inductor component 1 is singulated through the feeding wiring, electrolytic plating can be easily added, and the distance between wirings can be reduced. Further, by additionally performing electrolytic plating to reduce the distance between the first and second spiral wirings 21 and 22, the magnetic coupling of the first and second spiral wirings 21 and 22 can be improved, or the wiring widths of the first and second spiral wirings 21 and 22 can be increased, whereby the resistance can be reduced, or the external shape of the inductor component 1 can be made smaller.

Further, since the first and second spiral wirings 21 and 22 have the exposed portion 200, electrostatic breakdown resistance can be secured during processing of the inductor substrate. In each of the spiral wirings 21 and 22, the thickness (dimension in the Z direction) of the exposed surface 200a of the exposed portion 200 is preferably equal to or less than the thickness (dimension in the Z direction) of each of the spiral wirings 21 and 22 and equal to or more than 45 μm. When the thickness of the exposed surface 200a is equal to or less than the thickness of the spiral wirings 21 and 22, the ratio of the magnetic layers 11 and 12 can be increased, and the inductance can be improved. Further, by setting the thickness of the exposed surface 200a to 45 μm or more, the occurrence of disconnection in the vicinity of the exposed surface 200a can be reduced. The exposed surface 200a is preferably an oxide film. Accordingly, a short circuit can be suppressed between the inductor component 1 and its adjacent component.

The first to fourth columnar wirings 31 to 34 extend in the Z direction from the spiral wirings 21 and 22, respectively, and penetrate the inside of the second magnetic layer 12. The first columnar wiring 31 extends upward from the upper surface of one end of the first spiral wiring 21, and the end surface of the first columnar wiring 31 is exposed from the first main surface 10a of the base 10. The second columnar wiring 32 extends upward from the upper surface of the other end of the first spiral wiring 21, and the end surface of the second columnar wiring 32 is exposed from the first main surface 10a of the substrate 10. The third columnar wiring 33 extends upward from the upper surface of one end of the second spiral wiring 22, and an end surface of the third columnar wiring 33 is exposed from the first main surface 10a of the base 10. The fourth columnar wiring 34 extends upward from the upper surface of the other end of the second spiral wiring 22, and an end surface of the fourth columnar wiring 34 is exposed from the first main surface 10a of the base 10.

Therefore, the first columnar wiring 31, the second columnar wiring 32, the third columnar wiring 33, and the fourth columnar wiring 34 linearly extend from the first inductor element 2A and the second inductor element 2B to the end surface exposed from the first main surface 10a in the direction orthogonal to the end surface. Thus, the first external terminal 41, the second external terminal 42, the third external terminal 43, and the fourth external terminal 44 can be connected to the first inductor element 2A and the second inductor element 2B at a short distance, and the inductor component 1 can be made low in resistance and high in inductance. The first to fourth columnar wirings 31 to 34 are made of a conductive material, and are made of the same material as the spiral wirings 21 and 22, for example.

The first to fourth external terminals 41 to 44 are a plurality of metal films disposed on the first main surface 10a (the upper surface of the second magnetic layer 12) of the substrate 10. The first external terminal 41 is in contact with the end surface of the first columnar wiring 31 exposed from the first main surface 10a of the base 10, and is electrically connected to the first columnar wiring 31. Thereby, the first external terminal 41 is electrically connected to one end of the first spiral wiring 21. The second external terminal 42 is in contact with an end surface of the second columnar wiring 32 exposed from the first main surface 10a of the substrate 10, and is electrically connected to the second columnar wiring 32. Thereby, the second external terminal 42 is electrically connected to the other end of the first spiral wiring 21.

Similarly, the third external terminal 43 is in contact with an end surface of the third columnar wiring 33, is electrically connected to the third columnar wiring 33, and is electrically connected to one end of the second spiral wiring 22. The fourth external terminal 44 is in contact with an end surface of the fourth columnar wiring 34, is electrically connected to the fourth columnar wiring 34, and is electrically connected to the other end of the second spiral wiring 22.

In the inductor component 1, the first main surface 10a has a first edge 101 and a second edge 102 extending linearly corresponding to the sides of the rectangle. The first edge 101 and the second edge 102 are edges of the first main surface 10a connected to the first side surface 10b and the second side surface 10c of the substrate 10, respectively. The first external terminal 41 and the third external terminal 43 are arranged along a first edge 101 on the first side surface 10b side of the base body 10, and the second external terminal 42 and the fourth external terminal 44 are arranged along a second edge 102 on the second side surface 10c side of the base body 10. When viewed from a direction orthogonal to the first main surface 10a of the substrate 10, the first side surface 10b and the second side surface 10c of the substrate 10 are surfaces extending in the Y direction and coincide with the first edge 101 and the second edge 102. The arrangement direction of the first external terminal 41 and the third external terminal 43 is a direction connecting the center of the first external terminal 41 and the center of the third external terminal 43, and the arrangement direction of the second external terminal 42 and the fourth external terminal 44 is a direction connecting the center of the second external terminal 42 and the center of the fourth external terminal 44.

The insulating film 50 is provided on the first main surface 10a of the substrate 10 at a portion where the first to fourth external terminals 41 to 44 are not provided. However, the insulating film 50 may overlap the first to fourth external terminals 41 to 44 in the Z direction by covering the end portions of the first to fourth external terminals 41 to 44. The insulating film 50 is made of a resin material having high electrical insulation, such as acrylic resin, epoxy resin, or polyimide. This can improve the insulation between the first to fourth external terminals 41 to 44. In addition, the insulating film 50 replaces the mask used in the patterning of the first to fourth external terminals 41 to 44, thereby improving the manufacturing efficiency. When metal magnetic powder 136 is exposed from resin 135, insulating film 50 covers the exposed metal magnetic powder 136, thereby preventing metal magnetic powder 136 from being exposed to the outside. The insulating film 50 may contain a filler made of an insulating material such as silicon dioxide or barium sulfate.

As shown in fig. 2, the first external terminal 41, which is a multilayer metal film, includes a first metal film 411 in contact with the base 10 (second magnetic layer 12), a second metal film 412 covering the first metal film 411 from the side opposite to the base 10 with respect to the first metal film 411, and a catalyst layer 415 disposed between the first metal film 411 and the second metal film 412. The second, third, and fourth external terminals 42, 43, and 44 have the same configuration as the first external terminal 41, and therefore, only the first external terminal 41 will be described below.

The first metal film 411 has conductivity and has a function of reducing the resistance of the first external terminal 41. The first metal film 411 is formed by, for example, electroless plating, but may be formed by electrolytic plating. In the case where the first metal film 411 is formed by electroless plating, since the substrate 10 contains the metal magnetic powder 136, the first metal film 411 can be deposited on the metal magnetic powder 136 by a substitution reaction with the metal magnetic powder 136, and the adhesion between the substrate 10 and the first metal film 411 can be improved.

The second metal film 412 has solder corrosion resistance and covers the first metal film 411, so that solder corrosion of the first metal film 411 of the first external terminal 41 due to mounting of solder can be suppressed. The second metal film 412 is formed by electroless plating, for example, with the aid of a catalyst layer 415.

The catalyst layer 415 has a film-like base portion 415a and a plurality of convex portions 415b provided on the base portion 415 a. The convex portion 415b protrudes toward the second metal film 412 side and enters the second metal film 412. Accordingly, the anchor effect of the convex portion 415b improves the adhesion force between the first metal film 411 and the second metal film 412. Specifically, when the inductor component 1 is manufactured, mounted, or used, although stress may be generated in the first metal film 411 or the second metal film 412 due to a difference in linear expansion coefficient between the first metal film 411 and the second metal film 412 or an external force acting on the first external terminal 41, the convex portion 415b of the catalyst layer 415 becomes an anchor to the second metal film 412, and the adhesion force between the first metal film 411 and the second metal film 412 is improved. The catalyst layer 415 is formed by, for example, a substitution reaction with the first metal film 411.

The height a of the convex sections 415b of the catalyst layer 415 is preferably 2 times or more the film thickness t of the portions (in other words, the base sections 415a) of the catalyst layer 415 other than the convex sections 415 b. The height a and the film thickness t are measured in parallel to the Z direction for the convex portion 415b and the base portion 415a, respectively.

This can increase the height a of the convex portion 415b, and the anchor effect of the convex portion 415b further increases the adhesion force between the first metal film 411 and the second metal film 412. When the internal stress is accumulated in the second metal film 412, cracks are more likely to be generated in the convex portions 415b than in the second metal film 412, and the internal stress of the second metal film 412 can be reduced. Therefore, the convex portion 415b may have a crack, and the internal stress of the second metal film 412 can be reliably reduced by the crack.

As the measurement conditions of the height or the film thickness (including the measurement of the height or the film thickness described below), the measurement conditions were observed and measured in a scanning transmission electron microscope (SEM) image of a cross section obtained by cutting the measurement target (in the above case, the first external terminal 41) at the center of a plane perpendicular to the measurement dimension (height or film thickness) of the measurement target. Specifically, a sample such as the inductor member 1 is processed to expose a cross section passing through the center of the multilayer metal film to be measured, and the cross section is measured in an image obtained at a magnification of 1 ten thousand times using an SEM. The height a of the convex portion 415b may be measured as the maximum size, and the film thickness t of the base portion 415a may be measured at five positions except the end portion and the average value thereof may be calculated. The following film thickness was calculated in the same manner.

The thickness t of the catalyst layer 415 except for the convex sections 415b (in other words, the base sections 415a) is preferably 10nm to 30 nm.

The second metal layer can be formed satisfactorily by the film thickness t of 10nm or more, and the influence of the catalyst layer on the electrical, physical, and chemical characteristics of the first external terminal 41 can be reduced by the film thickness t of 30nm or less.

The height a of the convex portion 415b of the catalyst layer 415 is preferably 1/2 or less of the film thickness T2 of the second metal film 412. This can sufficiently ensure solder corrosion resistance of the second metal film 412.

It is preferable that the catalyst layer 415 contains a metal more noble than the first metal film 411. Thereby, the catalyst layer 415 can be formed by a substitution reaction with the first metal film 411.

The first metal film 411 has a plurality of holes 411a on the catalyst layer 415 side. The adjacent hole portions 411a may be separated or may be connected. The internal stress stored in the first external terminal 41 (multilayer metal film) between the first metal film 411 and the second metal film 412 can be relaxed by the hole 411a of the first metal film 411. Specifically, when the inductor component 1 is manufactured, mounted, used, or the like, internal stress is generated in the first external terminal 41 such as between the first metal film 411 and the second metal film 412 due to the difference in the linear expansion coefficient between the first metal film 411 and the second metal film 412 and the action of an external force on the first external terminal 41, but the internal stress accumulated in the hole 411a of the first metal film 411 is released, so that the internal stress accumulated in the first external terminal 41 can be relaxed.

The hole 411a of the first metal film 411 is preferably hollow. Therefore, the decrease in the purity of the first metal film 411 due to the impurities mixed into the holes 411a of the first metal film 411 can be suppressed. In addition, impurities other than the material of the first metal film 411, for example, a composition (such as sulfur) other than the plating solution may be mixed into the hole 411a of the first metal film 411.

The pores 411a of the first metal film 411 preferably exist in a range B from the first main surface 411B of the first metal film 411 on the catalyst layer 415 side to a film thickness T1 equal to or less than 1/4 of the first metal film 411. Therefore, the area of the first metal film 411 where the hole 411a exists can be reduced, and the strength of the first metal film 411 can be ensured.

The size of the hole 411a of the first metal film 411 is preferably such that interlayer peeling does not occur between the first metal film 411 and the second metal film 412. Here, the degree to which peeling does not occur between the first metal film 411 and the second metal film 412 means that the size thereof is equal to or smaller than a certain value even when a large hole 411a is present, or when a plurality of holes 411a are present and the plurality of holes 411a communicate with each other, or the like, or the degree to which the first metal film 411 and the second metal film 412 electrically communicate with each other. Specifically, the size of the holes 411a is preferably 0.5 μm or less. Further, the resistance between the first metal film 411 and the second metal film 412 is preferably 1m Ω or less. In these cases, it can be determined that peeling does not occur between the first metal film 411 and the second metal film 412. This ensures the function and reliability of the first external terminal 41 (multilayer metal film) including the first metal film 411 and the second metal film 412.

It is preferable that the first metal film 411 has a hardness smaller than that of the second metal film 412. Here, the hardness refers to, for example, vickers hardness. Therefore, the accumulation of internal stress can be further alleviated by the first metal film 411 being softer than the second metal film 412.

The first metal film 411 preferably contains Cu. This can ensure the conductivity of the first external terminal 41 at low cost. In addition, since the hardness of the first metal film 411 can be reduced, the internal stress of the first external terminal 41 including the first metal film 411 can be reduced. In addition, the film thickness of the first metal film 411 is preferably thicker than the other metal films of the first external terminal 41, and in this case, the conductivity of the first external terminal 41 can be improved and the internal stress can be further reduced. The first metal film 411 is not limited to Cu, and may contain at least one of Ag, Au, Al, Ni, Fe, and Pd.

The second metal film 412 preferably contains Ni. This can easily improve the solder corrosion resistance of the first external terminal 41. In addition, this also reduces migration of the first metal film 411. The second metal film 412 is not limited to Ni, and may contain at least one of Pd, Pt, Co, and Fe.

Preferably, the catalyst layer 415 contains Pd. This makes it possible to easily form the catalyst layer 415 with a metal that is more noble than the metal contained in the first metal film 411, and to easily promote oxidation of a reducing agent such as hypophosphorous acid when the second metal film 412 is formed by electroless plating, thereby further promoting deposition of the second metal film 412. The catalyst layer 415 is not limited to Pd, and may contain at least one of Ag, Cu, Pt, and Au.

Preferably, as shown by the virtual line in fig. 2, the first external terminal 41 further includes a third metal film 413 having solder wettability on the second metal film 412. This can improve the solder wettability of the first external terminal 41. The third metal film 413 contains, for example, at least one of Au, Sn, Pd, and Ag.

(production method)

Next, a method for manufacturing the inductor component 1 will be described.

As shown in fig. 3A, the upper surface of the base 10 is ground by polishing or the like in a state where the base 10 covers the plurality of spiral wirings 21 and 22 and the plurality of columnar wirings 31 to 34, so that the end surfaces of the columnar wirings 31 to 34 are exposed from the upper surface of the base 10. Thereafter, as shown in fig. 3B, an insulating film 50 shown by hatching is formed on the entire upper surface of the substrate 10 by a coating method such as spin coating or screen printing, a dry method such as dry film resist pasting, or the like. The insulating film 50 is, for example, a photosensitive resist.

Then, the insulating film 50 is removed by photolithography, laser, drill, sandblasting, or the like in the region where the external terminals are formed, thereby forming the through-holes 50a in the insulating film 50 in which the end surfaces of the columnar wirings 31 to 34 and a part of the base 10 (second magnetic layer 12) are exposed. In this case, as shown in fig. 3B, the entire end surfaces of the columnar wirings 31 to 34 may be exposed through the through-hole 50a, or a part of the end surfaces of the columnar wirings 31 to 34 may be exposed. Further, the end surfaces of the plurality of columnar wirings 31 to 34 may be exposed from one through hole 50 a.

Thereafter, as shown in fig. 3C, a plurality of metal films 410 shown in hatching are formed in the through-holes 50a by a method described later, thereby forming the mother substrate 100. The multilayer metal films 410 constitute external terminals 41 to 44 before cutting. Thereafter, as shown in fig. 3D, the mother substrate 100, that is, the plurality of sealed spiral wirings 21 and 22 are singulated for every two spiral wirings 21 and 22 along the cutting line C using a dicing blade or the like, thereby manufacturing the plurality of inductor components 1. The multilayer metal film 410 is cut along the cutting line C to form the external terminals 41 to 44. The method for manufacturing the external terminals 41 to 44 may be a method for cutting the multilayer metal film 410 as described above, or a method for forming the multilayer metal film 410 after removing the insulating film 50 so that the through holes 50a are formed in the shape of the external terminals 41 to 44 in advance.

(method for producing multilayer Metal film 410)

The method for manufacturing the multilayer metal film 410 will be described. Fig. 4A is a diagram showing an SEM image of a cross section obtained by cutting the first external terminal 41 (an example of the multilayer metal film 410) of the inductor component 1. Fig. 4B is an enlarged view of the vicinity of the catalyst layer 415 of fig. 4A. Fig. 4A and 4B are cross-sectional views obtained by cutting the first external terminal 41 at the center of the plane perpendicular to the film thickness of the first external terminal 41 (the principal plane where the first external terminal 41 is exposed) as described above. In fig. 4A and 4B, the lower direction is the Z direction, contrary to the upper and lower directions in fig. 1B and 2.

As described above, in the state where the insulating film 50 has the through-hole 50a, the end faces of the columnar wirings 31 to 34 and the substrate 10 are exposed from the through-hole 50 a. A Cu layer is formed by electroless plating or the like on the end surfaces of the columnar wirings 31 to 34 exposed from the through-holes 50a and the upper surface of the base 10, and serves as a first metal film 411 having conductivity and contacting the base 10.

Next, a Pd layer is formed on the first metal film 411 as a catalyst layer 415 for forming the second metal film 412. Specifically, the Pd layer is formed by, for example, performing a replacement Pd catalyst treatment. Here, in the above-described replacement Pd catalyst treatment, by selecting the treatment conditions to specific conditions, the convex portion 415b protruding toward the upper layer (second metal film 412) side is formed in the catalyst layer 415. Specifically, for example, in the replacement Pd catalyst treatment, the convex portion 415B shown in fig. 4A and 4B is formed by setting the Pd concentration to 0.02g/L, the temperature to 45 ℃, and the time to 10 min. In this case, the minimum film thickness and the maximum film thickness of the catalyst layer 415 including the convex sections 415b are 2nm and 205nm, respectively.

Next, a Ni layer is formed as the second metal film 412 having solder corrosion resistance by electroless plating or the like on the catalyst layer 415 on which the convex sections 415b are formed. Thereby, the convex portion 415b has a shape of penetrating into the second metal film 412.

Next, an Au layer is formed as the third metal film 413 having solder wettability by electroless plating treatment or the like on the second metal film 412. This enables the formation of the multilayer metal film 410.

This manufacturing condition is merely an example, and the manufacturing condition is not limited as long as the convex portion 415b is obtained. For example, in the above-described manufacturing method, the catalyst layer 415 contains Pd as a metal that promotes oxidation of the reducing agent in the Ni plating solution for forming the Ni layer as the second metal film 412, and thereby the deposition of the Ni layer can be promoted by electroless plating treatment using the Pd layer as a catalyst. On the other hand, the catalyst layer 415 is not limited to a catalyst in the electroless plating treatment, and may be a layer (catalyst) containing a metal that promotes deposition of the second metal film when the second metal film 412 is formed by another known method.

In addition, since the catalyst layer 415 contains Pd, which is a metal more noble than the Cu layer as the first metal film 411, the Pd layer can be easily formed by a substitution reaction with the Cu layer. On the other hand, the catalyst layer 415 may be formed on the Cu layer by other known methods, and may be a metal that is less expensive than the Cu layer.

(Structure of multilayer Metal film 410)

The structure of the aforementioned multilayer metal film 410 will be further explained. Fig. 5 is a diagram showing an SEM image of a cross section obtained by cutting the first external terminal 41 (an example of the multilayer metal film 410) of the inductor component 1. Fig. 5 is an image obtained by cutting a plane perpendicular to the film thickness of the first external terminal 41 (i.e., a cross section passing through the center of the main surface where the first external terminal 41 is exposed) as described above. In fig. 5, the lower direction is the Z direction, as in fig. 4A and 4B.

As shown in fig. 5, in the multilayer metal film 410, the first metal film 411 has a hole portion 411a on the catalyst layer 415 side. The size of the holes 411a of the first metal film 411 is 0.5 μm or less. Further, there are a plurality of holes 411a, and the maximum number of the holes 411a communicating with each other is 10 or less, and is substantially 5 front and rear in fig. 5. In addition, the first metal film 411 and the second metal film 412 are electrically connected to each other, and the resistance between the first metal film 411 and the second metal film 412 is 1m Ω or less. In this case, it can be determined that the first metal film 411 and the second metal film 412 are electrically connected without any problem, and that peeling does not occur between the first metal film 411 and the second metal film 412. As described above, the first metal film 411 can relax the internal stress stored in the multilayer metal film 410 through the holes 411a provided on the catalyst layer 415 side.

In the hole 411a, for example, when the catalyst layer 415 made of Pd is formed on the first metal film 411 made of Cu, the hole 411a can be formed on the catalyst layer 415 side of the first metal film 411 by selecting the process conditions to be specific conditions in the replacement process from Cu to Pd. Specifically, it was confirmed that the hole 411a as shown in fig. 5 could be formed by setting the Pd concentration of the treatment liquid used in the replacement treatment to 3g/L and the temperature to 25 ℃.

Note that this manufacturing condition is merely an example, and is not limited as long as the hole 411a can be obtained.

The formation of the convex portions 415b and the formation of the holes 411a can be performed independently, but the convex portions 415b and the holes 411a can be formed simultaneously by adjusting the concentration of the treatment liquid, the treatment temperature, and the treatment time, or only the convex portions 415b and only the holes 411a can be formed.

The present disclosure is not limited to the above-described embodiments, and modifications may be made without departing from the scope of the present disclosure.

In the above embodiment, two of the first inductor element and the second inductor element are disposed in the base, but three or more inductor elements may be disposed, and in this case, six or more external terminals and six or more columnar wirings are provided.

In the above embodiment, the number of turns of the spiral wiring included in the inductor element is less than 1 turn, but may be a curve in which the number of turns of the spiral wiring exceeds one turn. The total number of spiral wirings included in the inductor element is not limited to 1 layer, and may be a multilayer structure having two or more layers. The first spiral wiring of the first inductor element and the second spiral wiring of the second inductor element are not limited to a configuration in which they are arranged on the same plane parallel to the first main surface, and may be a configuration in which the first spiral wiring and the second spiral wiring are arranged in a direction orthogonal to the first main surface.

In the above embodiment, the external terminal is provided on the surface of the blank, but at least a part of the external terminal may be embedded in the blank. For example, the first metal film of the external terminal may be embedded in the blank, and the second metal film or the third metal film of the external terminal may be exposed from the surface of the blank.

In the above-described embodiment, the multilayer metal film is used as the external terminal of the inductor component, but is not limited thereto, and for example, the multilayer metal film may be an internal electrode of the inductor component. The multilayer metal film is not limited to the inductor component, and may be applied to other electronic components such as a capacitor component and a resistor component, and may be applied to a circuit board on which these electronic components are mounted. For example, the multilayer metal film may be a wiring pattern of a circuit board.

In the above embodiment, the first metal film has the hole portion on the catalyst layer side, but the first metal film may not have the hole portion.