JP7272500B2 - Multilayer metal film and inductor components - Google Patents

Description

The present invention relates to multilayer metal films and inductor components.

2. Description of the Related Art Conventionally, in electronic parts such as inductor parts, multilayer metal films in which metal films are laminated are used for internal electrodes constituting electric elements and external terminals serving as terminals of electric elements. For example, the inductor component described in Japanese Patent Application Laid-Open No. 2014-13815 (Patent Document 1) includes a substrate, spiral wiring provided on both sides of the substrate, a magnetic layer covering the spiral wiring, and a magnetic layer provided on the surface of the magnetic layer. and a lead wire electrically connecting the spiral wire and the external terminal. The spiral wiring is a multilayer metal film composed of a Cu base layer formed on a substrate by an electroless plating process and two Cu electrolytic plating layers formed on the base layer by electroplating twice. The external terminals are multilayer metal films formed by sputtering or screen printing before singulation and plated after singulation.

JP 2014-13815 A

In a multilayer metal film, the main surfaces of the laminated metal films are adhered to each other by chemical or physical bonding force. Here, electronic components are subjected to heat, electricity, and physical forces during manufacturing, mounting, and use. Delamination may occur between them. In the future, as electronic components continue to become smaller and multilayer metal films become finer and thinner, the above-mentioned delamination will occur even under manufacturing, mounting, and usage conditions that were previously unproblematic. there's a possibility that.

Accordingly, an object of the present disclosure is to provide a multilayer metal film with improved adhesion between metal films and an inductor component including the multilayer metal film.

In order to solve the above problems, a multilayer metal film, which is one aspect of the present disclosure,
A metal film disposed on an insulating substrate,
a conductive first metal film in contact with the substrate;
a second metal film having solder erosion resistance covering the first metal film from the side opposite to the base with respect to the first metal film;
a catalyst layer disposed between the first metal film and the second metal film;
The catalyst layer has a protrusion that protrudes toward the second metal film and penetrates into the second metal film.

According to the above aspect, the catalyst layer has a convex portion that protrudes toward the second metal film and penetrates into the second metal film. Improves adhesion. Note that the catalyst layer is a layer containing a metal that promotes deposition of the second metal film on the upper layer side. For example, when the second metal film is a film containing Ni, a layer containing Pd or the like that promotes oxidation of the reducing agent in the plating solution during Ni plating is arranged between the first metal film and the second metal film. If so, the layer containing Pd or the like can be used as a catalyst to accelerate deposition of the second metal film by electroless plating, so the layer becomes a catalyst layer.

In one embodiment, the height of the protrusions of the catalyst layer is at least twice the thickness of the portion of the catalyst layer other than the protrusions.

According to the above embodiment, the adhesion between the first metal film and the second metal film is further improved. In addition, when internal stress is accumulated in the second metal film, cracks are more likely to occur in the protrusions than in the second metal film, and the internal stress in the second metal film can be reduced.

In one embodiment, the film thickness of the portion of the catalyst layer other than the convex portion is 10 nm or more and 30 nm or less.

According to the above embodiment, the second metal film can be satisfactorily formed, and the influence of the catalyst layer on the electrical, physical, and chemical properties of the multilayer metal film can be reduced.

In one embodiment, the height of the protrusions of the catalyst layer is 1/2 or less of the film thickness of the second metal film.

According to the above embodiment, the solder erosion resistance of the second metal film can be sufficiently ensured.

Further, in one embodiment, the catalyst layer contains a nobler metal than the first metal film.

According to the embodiment, the catalyst layer can be easily formed by the substitution reaction with the first metal film.

Also, in one embodiment,
The base has a magnetic resin layer containing a resin and metal magnetic powder contained in the resin,
The first metal film contacts the magnetic resin layer.

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

In one embodiment, a third metal film having solder wettability is further provided on the second metal film.

According to the 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. Moreover, since the hardness of the first metal film can be reduced, the internal stress of the multilayer metal film can be reduced.

In one embodiment, the second metal film contains Ni.

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

Also, in one embodiment, the catalyst layer contains Pd.

According to the embodiment, the catalyst layer can be easily constructed.

Also, in one embodiment of the inductor component,
a substrate;
the multilayer metal film;
an inductor element disposed within the base;
The multilayer metal film is an external terminal exposed from the base and electrically connected to the inductor element.

According to the embodiment, it is possible to provide an inductor component in which peeling inside the external terminals is reduced.

According to the multilayer metal film and the inductor component according to one aspect of the present disclosure, it is possible to improve the adhesion between the metal films of the multilayer metal film.

1 is a perspective plan view showing a first embodiment of an inductor component; FIG. FIG. 1B is a cross-sectional view taken along line AA of FIG. 1A; 1C is a partially enlarged view of FIG. 1B; FIG. It is explanatory drawing explaining the manufacturing method of inductor components. It is explanatory drawing explaining the manufacturing method of inductor components. It is explanatory drawing explaining the manufacturing method of inductor components. It is explanatory drawing explaining the manufacturing method of inductor components. FIG. 4 is a scanning electron microscope image of the first embodiment of the inductor component; 3 is an enlarged image diagram of an external terminal; FIG. FIG. 10 is a scanning electron microscope image of the second embodiment of the inductor component;

An inductor component, which is one aspect of the present disclosure, will be described in detail below with reference to the illustrated embodiments. Note that the drawings are partially schematic and may not reflect actual dimensions or proportions.

(First embodiment)
(composition)
1A is a perspective plan view showing a first embodiment of an inductor component; FIG. FIG. 1B is a cross-sectional view taken along line AA of FIG. 1A. FIG. 2 is a partially enlarged view of FIG. 1B.

The inductor component 1 is, for example, a surface-mounted electronic component mounted on a circuit board mounted on electronic equipment such as personal computers, DVD players, digital cameras, TVs, mobile phones, and car electronics. However, the inductor component 1 may be a board-embedded electronic component instead of the surface-mounted type. Also, the inductor component 1 is, for example, a rectangular parallelepiped component 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 truncated cone shape, or a truncated polygonal pyramid shape.

As shown in FIGS. 1A and 1B, inductor component 1 includes substrate 10 having insulating properties, first inductor element 2A and second inductor element 2B arranged in substrate 10, and rectangular second inductor element 2B of 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 base 10 so that the end faces are exposed from the first main surface 10a, and the first main surface 10a of the base 10. A first external terminal 41 , a second external terminal 42 , a third external terminal 43 and a fourth external terminal 44 arranged thereon, and an insulating film 50 provided on the first major surface 10 a of the base 10 are provided. In the drawing, the direction parallel to the thickness of the inductor component 1 is the Z direction, the forward Z direction is the upper side, and the reverse Z direction is the lower side. In a plane perpendicular to the Z direction, the longitudinal direction of inductor component 1 is defined as the X direction, and the lateral direction of inductor component 1 is defined as the Y direction.

The substrate 10 has an insulating layer 61 , a first magnetic layer 11 arranged on a lower surface 61 a of the insulating layer 61 , and a second magnetic layer 12 arranged on an upper surface 61 b of the insulating layer 61 . The first main surface 10 a of the substrate 10 corresponds to the upper surface of the second magnetic layer 12 . The substrate 10 has a three-layer structure consisting of an insulating layer 61, a first magnetic layer 11 and a second magnetic layer 12. A single-layer structure with only a magnetic layer, a two-layer structure with only a magnetic layer and an insulating layer, and a plurality of magnetic layers. and four or more layers of insulating layers.

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

The first magnetic layer 11 and the second magnetic layer 12 have a high magnetic permeability, are layered with a rectangular main surface, and contain a resin 135 and metal magnetic powder 136 contained in the resin 135 . The resin 135 is an organic insulating material such as epoxy resin, bismaleimide, liquid crystal polymer, polyimide, or the like. The metal magnetic powder 136 is, for example, a magnetic metal material such as FeSi-based alloys such as FeSiCr, FeCo-based alloys, Fe-based alloys such as NiFe, or amorphous alloys thereof. The average particle size of the metal magnetic powder 136 is, for example, 0.1 μm or more and 5 μm or less. At the manufacturing stage of inductor component 1, the average particle size of metal magnetic powder 136 can be calculated as a particle size (so-called D50) corresponding to an integrated value of 50% in a particle size distribution determined by a laser diffraction/scattering method. The content 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 size of the metal magnetic powder 136 is 5 μm or less, the DC superimposition characteristics are further improved, and the fine powder can reduce iron loss at high frequencies. Magnetic powder of ferrite such as NiZn or MnZn may be used instead of the metal magnetic powder.

The first inductor element 2A and the second inductor element 2B include a first spiral wire 21 and a second spiral wire 22 arranged parallel to the first main surface 10a of the base 10, respectively. As a result, the first inductor element 2A and the second inductor element 2B can be formed 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 arranged on the same plane within the base 10 . Specifically, the first spiral wire 21 and the second spiral wire 22 are formed only on the upper side of the insulating layer 61 , that is, on the upper surface 61 b of the insulating layer 61 and are covered with the second magnetic layer 12 .

The first and second spiral wires 21 and 22 are wound in a plane. Specifically, the first and second spiral wires 21 and 22 are semi-elliptical arcs when viewed from the Z direction. That is, the first and second spiral wires 21 and 22 are curved wires wound about half a turn. Also, the first and second spiral wirings 21 and 22 include straight portions in the intermediate portions. In the present application, the “spiral” of spiral wiring means a curved shape wound in a plane including a spiral shape. It also includes a shape, and the curvilinear shape may include a partial straight portion.

The thickness of the first and second spiral wires 21 and 22 is preferably, for example, 40 μm or more and 120 μm or less. As an example of the first and second spiral wires 21 and 22, the thickness is 45 μm, the wire width is 40 μm, and the space between the wires is 10 μm. The space between wirings is preferably 3 μm or more and 20 μm or less to ensure insulation.

The first and second spiral wirings 21 and 22 are made of a conductive material, such as a metal material with low electric resistance such as Cu, Ag, and Au. In the present embodiment, the inductor component 1 has only one layer of the first and second spiral wirings 21 and 22, so that the height of the inductor component 1 can be reduced. The first and second spiral wires 21 and 22 may be multilayer metal films. For example, a conductive layer such as Cu or Ag is formed on a base layer such as Cu or Ti formed by electroless plating. It may be a structure that is

The first spiral wiring 21 has a first end and a second end electrically connected to the first columnar wiring 31 and the second columnar wiring 32 positioned on the outer side, respectively. It has a curved shape that draws an arc toward the center of the inductor component 1 . The first spiral wiring 21 has pad portions at both ends thereof, the width of which is larger than that of the spiral portion, and is directly connected to the first and second columnar wirings 31 and 32 at the pad portions.

Similarly, the second spiral wiring 22 has a first end and a second end electrically connected to the third and fourth columnar wirings 33 and 34 positioned on the outer side, respectively. It has a curved shape that draws an arc from the wiring 34 toward the center of the inductor component 1 .

Here, in each of the first and second spiral wires 21 and 22, the curve drawn by the first and second spiral wires 21 and 22 and the straight line connecting both ends of the first and second spiral wires 21 and 22 Let the enclosed range be an inner diameter part. At this time, when viewed from the Z direction, the inner diameter portions of the first and second spiral wires 21 and 22 do not overlap, and the first and second spiral wires 21 and 22 are separated from each other.

From the connection positions of the first and second spiral wires 21 and 22 to the first to fourth columnar wires 31 to 34, the wires further extend in a direction parallel to the X direction and outside the inductor component 1. , and this wiring is exposed to the outside of the inductor component 1 . That is, the first and second spiral wirings 21 and 22 have exposed portions 200 exposed to the outside from side surfaces (surfaces parallel to the YZ plane) parallel to the stacking direction of inductor component 1 .

This wiring is to be connected to the power supply wiring when performing additional electrolytic plating after forming the shapes of the first and second spiral wirings 21 and 22 in the manufacturing process of the inductor component 1 . With this power supply wiring, additional electrolytic plating can be easily performed in the state of the inductor substrate before the inductor component 1 is singulated, and the distance between the wirings can be narrowed. Further, by additionally performing electrolytic plating, the distance between the first and second spiral wires 21 and 22 is narrowed, thereby enhancing the magnetic coupling between the first and second spiral wires 21 and 22, , the wiring width of the second spiral wirings 21 and 22 can be increased to reduce the electrical resistance, and the outer shape of the inductor component 1 can be reduced.

In addition, since the first and second spiral wirings 21 and 22 have the exposed portions 200, it is possible to ensure resistance to electrostatic breakdown during processing of the inductor substrate. In each of the spiral wires 21 and 22, the thickness (dimension along the Z direction) of the exposed surface 200a of the exposed portion 200 is preferably equal to or less than the thickness (dimension along the Z direction) of each spiral wire 21 and 22, and , 45 μm or more. By setting the thickness of the exposed surface 200a to be equal to or less than the thickness of the spiral wires 21 and 22, the ratio of the magnetic layers 11 and 12 can be increased and the inductance can be improved. Moreover, since the thickness of the exposed surface 200a is 45 μm or more, occurrence of disconnection near the exposed surface 200a can be reduced. The exposed surface 200a is preferably an oxide film. According to this, it is possible to suppress a short circuit between inductor component 1 and its adjacent components.

The first to fourth columnar wires 31 to 34 extend from the spiral wires 21 and 22 in the Z direction and pass through 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 major surface 10 a 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 major surface 10 a of the base 10 . The third pillar-shaped wiring 33 extends upward from the top surface of one end of the second spiral wiring 22 , and the end surface of the third pillar-shaped wiring 33 is exposed from the first main surface 10 a of the base 10 . The fourth columnar wire 34 extends upward from the upper surface of the other end of the second spiral wire 22 , and the end face of the fourth columnar wire 34 is exposed from the first main surface 10 a 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 extend from the first inductor element 2A and the second inductor element 2B to the end surface exposed from the first main surface 10a. , extending linearly in a direction orthogonal to the end face. Thereby, the first external terminal 41, the second external terminal 42, the third external terminal 43, the fourth external terminal 44, and the first inductor element 2A, the second inductor element 2B can be connected at a shorter distance. , the inductor component 1 can be made to have a low resistance and a high inductance. The first to fourth columnar wirings 31 to 34 are made of a conductive material, for example, the same material as the spiral wirings 21 and 22 .

The first to fourth external terminals 41 to 44 are multilayer metal films arranged on the first main surface 10a of the substrate 10 (upper surface of the second magnetic layer 12). The first external terminal 41 is in contact with the end surface of the first columnar wiring 31 exposed from the first main surface 10 a of the base 10 and 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 the end surface of the second columnar wiring 32 exposed from the first main surface 10a of the base 10 and 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 contacts the end face 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 contacts the end face 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 sides of a rectangular shape. A first edge 101 and a second edge 102 are edges of the first main surface 10a that are continuous with the first side surface 10b and the second side surface 10c of the substrate 10, respectively. The first external terminals 41 and the third external terminals 43 are arranged along the first edge 101 on the side of the first side surface 10 b of the base 10 , and the second external terminals 42 and the fourth external terminals 44 are arranged along the first edge 101 of the base 10 . They are arranged along the second edge 102 on the side of the two side surfaces 10c. When viewed from a direction orthogonal to the first main surface 10a of the base 10, the first side 10b and the second side 10c of the base 10 are surfaces along the Y direction, and 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 the 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 the 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 portions of the first main surface 10a of the substrate 10 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 having the ends of the first to fourth external terminals 41 to 44 run over the insulating film 50 . The insulating film 50 is made of, for example, a resin material with high electrical insulation such as acrylic resin, epoxy resin, polyimide, or the like. Thereby, the insulation between the first to fourth external terminals 41 to 44 can be improved. In addition, the insulating film 50 serves as a mask for pattern formation of the first to fourth external terminals 41 to 44, thereby improving manufacturing efficiency. Further, when the metal magnetic powder 136 is exposed from the resin 135, the insulating film 50 covers the exposed metal magnetic powder 136, thereby preventing the metal magnetic powder 136 from being exposed to the outside. Note that the insulating film 50 may contain a filler made of an insulating material such as silica or barium sulfate.

As shown in FIG. 2, the first external terminal 41, which is a multi-layered metal film, includes a first metal film 411 in contact with the substrate 10 (second magnetic layer 12) and a first metal film 411 opposite to the substrate 10 with respect to the first metal film 411. It comprises a second metal film 412 covering the first metal film 411 from the side, and a catalyst layer 415 arranged between the first metal film 411 and the second metal film 412 . Since the configurations of the second, third, and fourth external terminals 42, 43, and 44 are the same as the configuration of the first external terminal 41, only the first external terminal 41 will be described below.

The first metal film 411 has conductivity and serves to reduce the electrical resistance of the first external terminal 41 . The first metal film 411 is formed by electroless plating, for example, but may be formed by electrolytic plating. When the first metal film 411 is formed by electroless plating, the substrate 10 contains the metal magnetic powder 136, so the substitution reaction with the metal magnetic powder 136 causes the first metal film 411 to be deposited on the metal magnetic powder 136. can be formed, and the adhesion between the substrate 10 and the first metal film 411 can be improved.

The second metal film 412 has solder erosion resistance, and by covering the first metal film 411 , solder erosion due to mounting solder of the first metal film 411 of the first external terminal 41 can be suppressed. The second metal film 412 is formed by, for example, electroless plating through the catalyst layer 415 .

The catalyst layer 415 has a film-like base portion 415a and a plurality of protrusions 415b provided on the base portion 415a. The convex portion 415 b protrudes toward the second metal film 412 and penetrates into the second metal film 412 . As a result, the adhesion between the first metal film 411 and the second metal film 412 is improved due to the anchoring effect of the projections 415b. Specifically, when the inductor component 1 is manufactured, mounted, or used, due to the difference in 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, the first Although stress may occur in the first metal film 411 or the second metal film 412 , the convex portion 415 b of the catalyst layer 415 serves as an anchor for the second metal film 412 , and the stress between the first metal film 411 and the second metal film 412 is reduced. improves adhesion. The catalyst layer 415 is formed by a substitution reaction with the first metal film 411, for example.

Preferably, the height A of the protrusions 415b of the catalyst layer 415 is twice or more the film thickness t of the portion of the catalyst layer 415 other than the protrusions 415b (that is, the base portion 415a). The height A and the film thickness t are dimensions of the convex portion 415b and the base portion 415a, respectively, measured in parallel with the Z direction.
As a result, the height A of the protrusion 415b can be increased, and the adhesion between the first metal film 411 and the second metal film 412 is further improved due to the anchor effect of the protrusion 415b. In addition, when internal stress is accumulated in the second metal film 412, cracks tend to occur in the protrusions 415b before the second metal film 412, and the internal stress in 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.
The height and film thickness measurement conditions (including the following height and film thickness measurement) are the center of the plane perpendicular to the measurement dimension (height and film thickness) of the object to be measured (the first external terminal 41 in the above case) Observe and measure with a scanning transmission electron microscope (SEM) image of a cross section of the object to be measured. Specifically, a sample such as the inductor component 1 is processed to expose a cross section passing through the center of the multi-layer metal film to be measured, and an image of the cross section is acquired at a magnification of 10,000 times using an SEM. Measure. The height A of the convex portion 415b can be obtained by measuring the maximum dimension, and the film thickness t of the base portion 415a can be obtained by measuring the film thickness at five locations excluding the end portions and calculating the average value thereof. good. The following film thicknesses are also calculated in the same manner.

Preferably, the film thickness t of the portion of the catalyst layer 415 other than the projections 415b (that is, the base portion 415a) is 10 nm or more and 30 nm or less.
When the film thickness t is 10 nm or more, the second metal layer can be formed satisfactorily, and when the film thickness t is 30 nm or less, the electrical, physical, and chemical properties of the first external terminal 41 are improved. The effect of layers can be reduced.

Preferably, the height A of the protrusions 415b of the catalyst layer 415 is 1/2 or less of the film thickness T2 of the second metal film 412. As shown in FIG. Thereby, the solder erosion resistance of the second metal film 412 can be sufficiently secured.

Preferably, catalyst layer 415 contains a nobler metal than 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. Adjacent holes 411a may be separated or connected. The internal stress accumulated in the first external terminal 41 (multilayer metal film) such as between the first metal film 411 and the second metal film 412 can be relieved by the hole portion 411 a of the first metal film 411 . Specifically, when the inductor component 1 is manufactured, mounted, used, etc., due to the difference in linear expansion coefficient between the first metal film 411 and the second metal film 412 and the action of external force on the first external terminal 41 , , internal stress occurs in the first external terminal 41 such as between the first metal film 411 and the second metal film 412, but the accumulated internal stress is released in the hole 411a of the first metal film 411, Internal stress accumulated in the first external terminal 41 can be relaxed.

Preferably, the inside of the hole 411a of the first metal film 411 is hollow. Therefore, it is possible to suppress the deterioration of the purity of the first metal film 411 due to the entry of impurities into the holes 411a of the first metal film 411 . Note that impurities other than the material of the first metal film 411 may be mixed in the hole portion 411a of the first metal film 411. For example, even if a composition (such as sulfur) other than the plating solution is mixed, good.

Preferably, the hole portion 411a of the first metal film 411 extends from the first main surface 411b of the first metal film 411 on the side of the catalyst layer 415 to 1/4 or less of the film thickness T1 of the first metal film 411. Existing. Therefore, the area where the hole 411a exists in the first metal film 411 can be reduced, and the strength of the first metal film 411 can be secured.

Preferably, the size of the hole 411a of the first metal film 411 is such that delamination does not occur between the first metal film 411 and the second metal film 412 . Here, the extent to which peeling does not occur between the first metal film 411 and the second metal film 412 means the case where a large hole 411a exists, or the case where a plurality of holes 411a exist and the plurality of holes 411a are separated from each other. Even in the case where the first metal film 411 and the second metal film 412 are electrically connected to each other, it refers to the degree to which the size is equal to or less than a certain value, or the degree to which the first metal film 411 and the second metal film 412 are electrically connected. Specifically, the size of the hole 411a is preferably 0.5 μm or less. Also, the electrical resistance between the first metal film 411 and the second metal film 412 is preferably 1 mΩ or less. In these cases, it can be determined that peeling has not occurred between the first metal film 411 and the second metal film 412 . Thereby, 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 can be ensured.

Preferably, the hardness of the first metal film 411 is less than the hardness of the second metal film 412 . Here, hardness is Vickers hardness, for example. Therefore, the first metal film 411, which is softer than the second metal film 412, can further alleviate the accumulation of internal stress.

Preferably, the first metal film 411 contains Cu. Thereby, the conductivity of the first external terminal 41 can be secured at low cost. Moreover, 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. The film thickness of the first metal film 411 is preferably thicker than the other metal films of the first external terminal 41. In this case, the internal stress can be further reduced while improving the conductivity of the first external terminal 41. . Note that the first metal film 411 is not limited to Cu, and may contain at least one of Ag, Au, Al, Ni, Fe, and Pd.

Preferably, the second metal film 412 contains Ni. Thereby, the solder erosion resistance of the first external terminals 41 can be easily improved. Moreover, this can also reduce the 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, catalyst layer 415 contains Pd. As a result, the catalyst layer 415 can be easily composed of a metal nobler than the metal contained in the first metal film 411, and when the second metal film 412 is formed by electroless plating, a reducing agent such as hypophosphorous acid can be used. Oxidation can be easily promoted, and deposition of the second metal film 412 can be further promoted. Note that the catalyst layer 415 is not limited to Pd, and may contain at least one of Ag, Cu, Pt, and Au.

Preferably, the first external terminal 41 further has a solder-wettable third metal film 413 on the second metal film 412, as indicated by the phantom lines in FIG. Thereby, the solder wettability of the first external terminals 41 can be improved. The third metal film 413 contains at least one of Au, Sn, Pd and Ag, for example.

(Production method)
Next, a method for manufacturing inductor component 1 will be described.

As shown in FIG. 3A, in a state in which the plurality of spiral wirings 21 and 22 and the plurality of columnar wirings 31 to 34 are covered with the substrate 10, the upper surface of the substrate 10 is ground by polishing or the like, and the end surfaces of the columnar wirings 31 to 34 are ground. are exposed from the upper surface of the substrate 10 . After that, as shown in FIG. 3B, the insulating film 50 indicated 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 application, or the like. The insulating film 50 is, for example, a photosensitive resist.
After that, by removing the insulating film 50 by photolithography, laser, drilling, blasting, or the like in the region where the external terminals are to be formed, the end surfaces of the columnar wirings 31 to 34 and part of the substrate 10 (second magnetic layer 12) are removed. is formed in the insulating film 50 to expose the through hole 50a. At this time, as shown in FIG. 3B, the entire end faces of the columnar wires 31 to 34 may be exposed from the through hole 50a, or part of the end faces of the columnar wires 31 to 34 may be exposed. Further, end faces of the plurality of columnar wirings 31 to 34 may be exposed from one through hole 50a.

After that, as shown in FIG. 3C, a multi-layered metal film 410 indicated by hatching is formed in the through-hole 50a by a method described later to form the mother substrate 100. As shown in FIG. The multilayer metal film 410 constitutes the external terminals 41 to 44 before cutting. After that, as shown in FIG. 3D, the mother substrate 100, that is, the plurality of sealed spiral wires 21 and 22 are singulated into two spiral wires 21 and 22 along cut lines C using a dicing blade or the like. to manufacture a plurality of inductor components 1. The multilayer metal film 410 is cut along cut lines C to form the external terminals 41-44. The method of manufacturing the external terminals 41 to 44 may be the method of cutting the multilayer metal film 410 as described above, or the insulating film 50 is formed in advance such that the through holes 50a are formed into the shapes of the external terminals 41 to 44. A method of forming the multilayer metal film 410 after removal may be used.

(Manufacturing method of multilayer metal film 410)
A method for manufacturing the multilayer metal film 410 described above 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. FIG. 4B is an enlarged image view near the catalyst layer 415 in FIG. 4A. 4A and 4B are image diagrams of a cross section of the first external terminal 41 cut at the center of the plane perpendicular to the film thickness of the first external terminal 41 (main surface where the first external terminal 41 is exposed) as described above. is. In FIGS. 4A and 4B, the vertical direction is opposite to that in FIGS. 1B and 2, and the downward direction is the Z direction.

As described above, when the through holes 50a are formed in the insulating film 50, the end surfaces of the columnar wirings 31 to 34 and the substrate 10 are exposed from the through holes 50a. A Cu layer is formed as a conductive first metal film 411 in contact with the substrate 10 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 substrate 10. do.

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 formation of the Pd layer is carried out, for example, by substitution Pd catalyst treatment. Here, in the substitution Pd catalyst treatment, by setting the treatment conditions to specific conditions, the catalyst layer 415 is formed with convex portions 415b that are convex toward the upper layer (second metal film 412) side. Specifically, for example, in the substitution Pd catalyst treatment, the Pd concentration is set to 0.02 g/L, the temperature is set to 45° C., and the time is set to 10 minutes, so that the protrusions 415b as shown in FIGS. 4A and 4B are formed. is formed. At this time, the range of the thickness of the entire catalyst layer 415 including the protrusions 415b is a minimum thickness of 2 nm and a maximum thickness of 205 nm.

Next, a Ni layer is formed as a second metal film 412 having resistance to solder erosion by electroless plating or the like on the catalyst layer 415 on which the protrusions 415b are formed. As a result, the convex portion 415b has a shape that penetrates into the second metal film 412 .

Next, an Au layer is formed on the second metal film 412 as a third metal film 413 having solder wettability by electroless plating or the like. In this manner, the multilayer metal film 410 can be formed.

Moreover, the manufacturing conditions are only an example, and the manufacturing conditions are not limited as long as the convex portion 415b can be obtained. For example, in the above manufacturing method, the catalyst layer 415 contains Pd as a metal that promotes oxidation of the reducing agent in the Ni plating solution that forms the Ni layer that is the second metal film 412. Electroless plating can promote the deposition of the Ni layer. On the other hand, the catalyst layer 415 is not limited to the catalyst in the electroless plating treatment, and is a layer containing a metal (catalyst ).

Moreover, since the catalyst layer 415 contains Pd, which is a nobler metal than the Cu layer that is 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 another known method, and may be made of a metal less noble than the Cu layer.

(Structure of multilayer metal film 410)
The structure of the multilayer metal film 410 described above will be further described. 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. As shown in FIG. FIG. 5 is an image view taken along a cross section passing through the center of the plane perpendicular to the film thickness of the first external terminal 41 (the main surface where the first external terminal 41 is exposed) as described above. In FIG. 5, the downward direction is the Z direction, as in FIGS. 4A and 4B.

As shown in FIG. 5, in the multilayer metal film 410, the first metal film 411 has a hole 411a on the catalyst layer 415 side. The size of the hole 411a of the first metal film 411 is 0.5 μm or less. In addition, there are a plurality of holes 411a, and the maximum number of the plurality of holes 411a communicating is 10 or less, which is approximately 5 in FIG. Also, the first metal film 411 and the second metal film 412 are electrically connected, and the electrical resistance between the first metal film 411 and the second metal film 412 is 1 mΩ 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 no peeling has occurred between the first metal film 411 and the second metal film 412 . As described above, the first metal film 411 can relieve the internal stress accumulated in the multilayer metal film 410 by the hole 411a on the catalyst layer 415 side.

For example, when the catalyst layer 415 made of Pd is formed on the first metal film 411 made of Cu, the hole 411a is formed by setting the processing conditions to specific conditions in the process of replacing Cu with Pd. A hole 411a can be formed on the catalyst layer 415 side of the metal film 411 . Specifically, for example, it was confirmed that the holes 411a as shown in FIG. there is

Note that the manufacturing conditions are merely an example, and the manufacturing conditions are not limited as long as the holes 411a can be obtained.

Further, the formation of the convex portion 415b and the formation of the hole portion 411a can be performed independently of each other. can be formed at the same time, or only the convex portion 415b and only the hole portion 411a can be formed.

Note that the present disclosure is not limited to the above-described embodiments, and design changes are possible without departing from the gist of the present disclosure.

In the above embodiment, two of the first inductor element and the second inductor element are arranged in the base, but three or more inductor elements may be arranged, and in this case, the external terminal and the columnar wiring are respectively , six or more.

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

In the above embodiments, the external terminals are provided on the surface of the element body, but at least part of the external terminals may be embedded in the element body. For example, the first metal film of the external terminal may be embedded in the element body, and the second metal film or the third metal film of the external terminal may be exposed from the surface of the element body.

In the above embodiments, the multilayer metal film is applied as the external terminal of the inductor component, but the present invention is not limited to this, and the multilayer metal film may be the internal electrode of the inductor component, for example. Moreover, the multilayer metal film is not limited to inductor parts, and may be applied to other electronic parts such as capacitor parts and resistor parts, and may be applied to circuit boards on which these electronic parts 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 holes on the catalyst layer side, but the first metal film does not have to have holes.

1 inductor component 2A first inductor element 2B second inductor element 10 substrate 101 first edge 102 second edge 10a first main surface 10b first side surface 10c second side surface 11 first magnetic layer 12 second magnetic layer 21 second 1 Spiral Wiring 22 Second Spiral Wiring 31 First Columnar Wiring 32 Second Columnar Wiring 33 Third Columnar Wiring 34 Fourth Columnar Wiring 41 First External Terminal (Multilayer Metal Film)
410 Multilayer metal film 411 First metal film 411a Hole 411b First main surface 412 Second metal film 413 Third metal film 415 Catalyst layer 415a Base portion 415b Projection 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 Insulating layer 100 Mother substrate 135 Resin 136 Metal magnetic powder A (projection) height B (hole) range t (base) film thickness T1 (first metal film) film thickness T2 ( film thickness of the second metal film)

Claims (13)

A metal film disposed on an insulating substrate,
a conductive first metal film in contact with the substrate;
a second metal film having solder erosion resistance covering the first metal film from the side opposite to the base with respect to the first metal film;
a catalyst layer disposed between the first metal film and the second metal film;
The catalyst layer has a film-like base portion and a plurality of convex portions provided on the base portion, and the convex portions are convex toward the second metal film and extend toward the second metal film. invade,
The first metal film has a plurality of holes on the catalyst layer side,
The multilayer metal film, wherein the inside of the hole of the first metal film is a cavity. 2. The multilayer metal film according to claim 1, wherein the height of said protrusions of said catalyst layer is at least twice the thickness of the portion of said catalyst layer other than said protrusions. 3. The multilayer metal film according to claim 1, wherein the film thickness of the portion of the catalyst layer other than the projections is 10 nm or more and 30 nm or less. 4. The multilayer metal film according to any one of claims 1 to 3, wherein the height of said protrusions of said catalyst layer is 1/2 or less of the film thickness of said second metal film. 5. The multilayer metal film according to claim 1, wherein said catalyst layer contains a metal more noble than said first metal film. The base has a magnetic resin layer containing a resin and metal magnetic powder contained in the resin,
6. The multilayer metal film according to claim 1, wherein said first metal film is in contact with said magnetic resin layer. 7. The multilayer metal film according to claim 1, further comprising a third metal film having solder wettability on said second metal film. 8. The multilayer metal film according to claim 1, wherein said first metal film contains Cu. 9. The multilayer metal film according to any one of claims 1 to 8, wherein said second metal film contains Ni. 10. The multilayer metal film according to any one of claims 1 to 9, wherein the catalyst layer contains Pd. 11. The multilayer metal film according to claim 1, wherein the shortest distance between two adjacent protrusions is greater than the height of said protrusions. 12. The multilayer metal film according to any one of claims 1 to 11, wherein said protrusions have cracks. a substrate;
a multilayer metal film according to any one of claims 1 to 12;
an inductor element disposed within the base;
The inductor component, wherein the multilayer metal film is an external terminal exposed from the base and electrically connected to the inductor element.

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