Electronic components

Abstract

This metal film comprises a metal foil, and a plurality of silica particles in which the average particle diameter is 100 (nm) or less. The plurality of silica particles are in contact the surface of the metal foil.

Description

Technical Field

[0001] The disclosed embodiments relate to , electric sub-components.

Background Art

[0002] Conventionally, metal foils such as copper foils have been used for the conductor layers of wiring boards. For example, a technique for forming a wiring board by attaching a copper foil to the surface of an insulating base material through an adhesive mixed with rigid particles has been disclosed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] The metal film of the present disclosure includes a metal foil and a plurality of silica particles having an average particle diameter of 100 nm or less. Further, a plurality of the silica particles are in contact with the surface of the metal foil.

Brief Description of the Drawings

[0005] [Figure 1] FIG. 1 is a cross-sectional view showing an example of the configuration of the metal film according to the embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing an example of the configuration of the wiring board according to the embodiment.

Modes for Carrying Out the Invention

[0006] Embodiments of the metal film and electronic components disclosed herein will be described below with reference to the attached drawings. However, the embodiments described below do not limit this disclosure. Furthermore, each embodiment can be combined as appropriate, provided that the processing content is not inconsistent. Also, the same parts are denoted by the same reference numerals in each of the embodiments below, and redundant descriptions are omitted.

[0007] Conventionally, metal foils such as copper foil have been used for the conductive layer of wiring boards. For example, a technology has been disclosed in which copper foil is attached to the surface of an insulating substrate via an adhesive containing rigid particles to form a wiring board.

[0008] However, conventional technology still had room for improvement in terms of enhancing the adhesion between the insulating layer and the metal foil. Therefore, there is a need for a technology that can solve the above problems and achieve good adhesive strength to the insulating layer.

[0009] <Metal film> Figure 1 is a cross-sectional view showing an example of a metal film 1 according to an embodiment. Figure 1(a) is a cross-sectional view showing the entire metal film 1, and Figure 1(b) is a magnified cross-sectional view of the surface of the metal film 1.

[0010] As shown in Figure 1, the metal film 1 according to this embodiment comprises a metal foil 10 and a plurality of silica particles 11.

[0011] The metal foil 10 is in the form of a thin film (foil) and mainly contains metal as its component. The metal foil 10 has a main surface 10a. The main surface 10a is an example of a surface. The metal foil 10 is not particularly limited and can be, for example, copper foil such as electrolytic copper foil or rolled copper foil, nickel foil, or composite foil made by layering these metal foils.

[0012] The thickness of the metal foil 10 is not particularly limited, and is, for example, 5 μm or more and 105 μm or less. The surface roughness of the metal foil 10 is not particularly limited, and may be, for example, 0.5 μm or less, or 0.3 μm or less. Also, the surface roughness of the metal foil 10 may be 0.001 μm or more.

[0013] The silica particles 11 are spherical and mainly contain silica (SiO2). The average particle size of the multiple silica particles 11 may be 100 nm or less, or 20 nm or less.

[0014] Furthermore, the particle size range of the multiple silica particles 11 may be, for example, the range of D10 (10% integrated) to D90 (90% integrated) when the particle size distribution is measured may be 5 nm or more and 50 nm or less, or 10 nm or more and 30 nm or less.

[0015] In the metal film 1 according to this embodiment, as shown in Figure 1(b), a plurality of nano-sized silica particles 11 may be in contact with the main surface 10a of the metal foil 10. This improves the adhesion between the metal foil 10 and the insulating layer 12 when the insulating layer 12 (see Figure 2) is positioned to be in contact with the main surface 10a of the metal foil 10.

[0016] This is because, since the metal film 1 according to the embodiment is composed of a metal foil 10 and a plurality of silica particles 11, there are almost no volatile components that evaporate during the firing process. Therefore, even after the firing process is performed to form the wiring board 2 (see Figure 2), the adhesive strength between the metal foil 10 and the insulating layer 12 is not easily impaired.

[0017] Furthermore, the metal film 1 according to this embodiment has a configuration in which a large number of nano-sized silica particles 11 are attached to the main surface 10a of the metal foil 10, and these nano-sized silica particles 11 exhibit high adhesive strength between themselves and the glass ceramic insulating layer 12.

[0018] Therefore, according to the embodiment, a metal film 1 having good adhesion strength to the insulating layer 12 can be realized. In the metal film 1 according to the embodiment, the silica particles 11 may adhere only to a part of the surface of the metal foil 10, or the silica particles 11 may adhere to the entire surface of the metal foil 10.

[0019] Also, in the embodiment, since the silica particles 11 contained in the metal film 1 are nano-sized, even if the silica particles 11 diffuse toward the insulating layer 12 side of the glass ceramics, the reduction of the dielectric properties of the insulating layer 12 can be reduced. Therefore, according to the embodiment, an electronic component having good high-frequency characteristics can be realized. The nano-sized silica particles 11 are present at the interface between the insulating layer 12 of the glass ceramics and the metal foil 10.

[0020] In addition, in the embodiment, an electrostatic attraction force may act between the metal foil 10 and the silica particles 11. Thereby, a strong bond can be realized between the metal foil 10 and the silica particles 11 without using a different material such as an adhesive. In this case, the electrostatic attraction force between the metal foil 10 and the silica particles 11 is evaluated using an electrostatic scanner. The electrostatic scanner can visualize and observe the generation of static electricity between the metal foil 10 and the silica particles 11.

[0021] Therefore, according to the embodiment, since the dropout of the silica particles 11 when handling the metal film 1 can be reduced, the metal film 1 can be easily handled in the manufacturing process of the electronic component.

[0022] In addition, in the embodiment, as shown in FIG. 1, the spherical silica particles 11 may be in point contact with the metal foil 10, and the portion of the metal foil 10 that is not in contact with the silica particles 11 may be exposed.

[0023] Here, the fact that the spherical silica particles 11 are in point contact with the metal foil 10 does not simply refer to the length of the contour interpreted as a point as in the case when two true spheres contact each other. In fact, although the silica particles 11 are spherical, they do not have the shape of a theoretical true sphere but rather a shape close to a true sphere.

[0024] Therefore, within the surface of the silica particles 11, there are portions with a curvature greater than the curvature estimated from the average radius of the silica particles 11, and the region where such a portion with a large curvature contacts the metal foil 10 has a contact area that is not a point but a surface having a predetermined area. The ratio of the contact area between the metal foil 10 and the silica particles 11 includes cases where it is 1 or more and 20 or less, and 5 or more and 10 or less when the contour length of the silica particles 11 is taken as 100.

[0025] The relative permittivity of the silica particles 11 is about 2.0 to 2.4. And since the metal foil 10 is in contact with the silica particles 11 having such a low relative permittivity, even when the insulating layer 12 of glass ceramics has a higher relative permittivity than the silica particles 11, a conductive layer with a high interfacial conductivity can be obtained due to the effect of the portion where the silica particles 11 are in contact. The silica particles 11 are planar-dispersed at the interface between the insulating layer 12 and the metal foil 10.

[0026] Also, in the embodiment, the portion of the silica particles 11 that contacts the metal foil 10 may have a neck-shaped neck portion (not shown). That is, among the silica particles 11, there may be particles having a neck portion between them and the metal foil 10.

[0027] Thereby, a stronger bond can be realized between the metal foil 10 and the silica particles 11 without using a different material such as an adhesive. Therefore, according to the embodiment, in the manufacturing process of electronic components, the metal film 1 can be handled more easily.

[0028] Furthermore, in the embodiment, when the unit area of ​​the metal foil 10 in a plan view is set to 1, the area ratio of the multiple silica particles 11 may be 1% or more and 60% or less. This makes it possible to achieve both adhesion between the metal foil 10 and the insulating layer 12 and electrical properties (for example, interfacial conductivity) in the electronic component.

[0029] For example, if the area ratio of multiple silica particles 11 is 1 (%), then 10 (μm) × 10 (μm) (i.e., the area is 100 (μm) 2 Multiple silica particles 11 are attached to the metal foil 10, with a diameter of 1 μm. 2 It will be occupied by the area of ​​).

[0030] Furthermore, if the diameter of the silica particle 11 is 20 nm, the area of ​​the silica particle 11 when viewed from above is 3.14 × 10⁻⁶. -4 (μm 2 )

[0031] Therefore, if the area ratio of multiple silica particles 11 is 1 (%), then the silica particles 11 on a 10 (μm) × 10 (μm) metal foil 10 will be 1 ÷ (3.14 × 10 -4 This means there are approximately 3184 of them.

[0032] Thus, in this embodiment, since a large number of silica particles 11 are present on the main surface 10a of the metal foil 10, a high adhesive strength can be achieved between the metal foil 10 and the insulating layer 12.

[0033] Furthermore, by setting the area ratio of the multiple silica particles 11 to 60% or less, all the silica particles 11 can be dispersed without overlapping on the main surface 10a of the metal foil 10. The multiple silica particles 11 are dispersed without overlapping in the thickness direction of the metal foil 10.

[0034] In addition, in this embodiment, the metal foil 10 may contain copper or nickel as its main component. When the metal foil 10 is mainly composed of copper, it is possible to obtain high interfacial conductivity and low DC electrical resistance as a conductor layer of the wiring board 2.

[0035] Furthermore, if the metal foil 10 is mainly composed of nickel, for example, a conductor with low resistance and high temperature resistance can be obtained as an electrode material for a fuel cell. In addition, if the metal foil 10 is mainly composed of nickel, it can also be useful as an internal electrode layer for a capacitor.

[0036] Furthermore, in the embodiment, the silica particles 11 may be aggregates of multiple primary particles having an average particle size of 1 nm or more and 5 nm or less. By forming the silica particles 11 from fine primary particles, the silica particles 11 have a higher surface energy.

[0037] This makes it possible to achieve an even stronger bond between the metal foil 10 and the silica particles 11 without the need for dissimilar materials such as adhesives. Therefore, according to this embodiment, the metal film 1 can be handled even more easily in the manufacturing process of electronic components.

[0038] <Wiring board> Figure 2 is a cross-sectional view showing an example of the configuration of a wiring board 2 according to an embodiment. Figure 2(a) is a cross-sectional view showing the entire wiring board 2, and Figure 2(b) is an enlarged cross-sectional view of the interface between the metal foil 10 and the insulating layer 12 in the wiring board 2. The wiring board 2 is an example of an electronic component.

[0039] As shown in Figure 2, the wiring board 2 according to the embodiment comprises a metal film 1 and an insulating layer 12. That is, the wiring board 2 according to the embodiment comprises a metal foil 10, a plurality of silica particles 11, and an insulating layer 12.

[0040] The insulating layer 12 is a thin plate and mainly contains an insulator. The material of the insulating layer 12 is not particularly limited and can be any of the following: glass ceramics, zirconia ceramics, or other ceramic materials, or organic resins.

[0041] Furthermore, in the wiring board 2 according to the embodiment, the metal foil 10 functions as a wiring layer. Thus, in the wiring board 2 according to the embodiment, since the wiring layer is composed of metal foil 10 rather than a metallized layer, a wiring board 2 with a conductive layer exhibiting high conductivity can be obtained. In this case, it is preferable that the metal foil 10 mainly contains copper.

[0042] Furthermore, in the wiring board 2 according to the embodiment, the metal foil 10 and the insulating layer 12 are joined such that the main surface 10a of the metal foil 10 is in contact with the main surface 12a of the insulating layer 12. In other words, in this embodiment, the metal foil 10 is joined to the insulating layer 12 via a plurality of silica particles 11. Therefore, as described above, in this embodiment, the adhesive strength between the metal foil 10 and the insulating layer 12 can be improved.

[0043] Furthermore, in this embodiment, since the silica particles 11 contained in the metal film 1 are nano-sized, even if these silica particles 11 diffuse to the insulating layer 12 side of the glass ceramic, the decrease in the dielectric properties of the insulating layer 12 can be reduced. Therefore, according to this embodiment, a wiring substrate 2 with good high-frequency characteristics can be realized.

[0044] <Electronic Components> Furthermore, this disclosure can also be applied to the following electronic component. This electronic component also has a metal foil 10 (see Figure 2), a plurality of silica particles 11 (see Figure 2), and an insulating layer 12 (see Figure 2).

[0045] The electronic component may be configured in the same way as the wiring board 2 described above, with the metal foil 10 placed on the main surface 12a of the insulating layer 12. Alternatively, the metal foil 10 may be placed on both sides of the insulating layer 12.

[0046] In this case, the material of the metal foil 10 is preferably nickel. When the material of the metal foil 10 is nickel, a dielectric ceramic material is suitable as the material for the insulating layer. A dielectric ceramic material may also be referred to as dielectric ceramics.

[0047] Examples of dielectric ceramics include ceramic materials whose main component is barium titanate. Here, "main component" refers to cases where barium titanate is present in 80% (mol%) or more of the dielectric ceramic. Dielectric ceramics are applied, for example, to the dielectric layer of multilayer ceramic capacitors.

[0048] <Fuel cell> Furthermore, this disclosure can also be applied to the following fuel cell. This fuel cell also has a metal foil 10 (see Figure 2), a plurality of silica particles 11 (see Figure 2), and an insulating layer 12 (see Figure 2).

[0049] Furthermore, this fuel cell cell has a fuel electrode and a support. The fuel electrode has a solid electrolyte material and nickel. In particular, the fuel electrode material in the fuel cell cell has zirconia as its main component. In this case, the material of the metal foil 10 is preferably nickel. In this case as well, the nickel conductor is preferably one in which multiple silica particles 11 are located on its surface. [Examples]

[0050] The embodiments of this disclosure will be described in detail below. In the embodiments described below, a metal film having copper foil will be shown first, followed by a wiring substrate having such a metal film and an insulating layer composed of glass ceramics, but this disclosure is not limited to the embodiments described below.

[0051] <Sample 1> First, a copper foil with a thickness of 18 μm was prepared as the material for the metal foil. Additionally, several silica particles with an average particle size of 20 nm were prepared. These silica particles were aggregates of primary particles with particle sizes ranging from approximately 1 nm to 10 nm.

[0052] Next, the prepared copper foil was treated with hydrochloric acid to remove the surface oxide film, followed by alkaline cleaning and rinsing with water.

[0053] Next, a process was carried out to adhere multiple silica particles to the copper foil after the water washing treatment. Specifically, first, an amount of silica particles was prepared that covered approximately 50% of the main surface area of ​​the copper foil.

[0054] Next, copper foil was attached to a metal substrate, a metal frame was placed around the copper foil, the above amount of silica particles was placed inside the frame, and ultrasonic waves were applied to the metal substrate to disperse the silica particles onto the copper foil.

[0055] After dispersion, a stainless steel metal plate was placed on top of the silica particles, and the silica particles were pressurized at a predetermined pressure through the metal plate. This resulted in obtaining a metal film of sample 1 with multiple silica particles adhering to its main surface. The ratio of adhering silica particles to the silica particles placed in the frame was approximately 10% to 20%.

[0056] Next, a wiring board for sample 1 was fabricated using the metal film obtained above. First, a glass ceramic green sheet with a thickness of 0.2 mm was prepared, and six of these green sheets were stacked.

[0057] Next, metal films were attached to both main surfaces of the green sheet. The green sheet and metal films were positioned so that the silica particles of the metal films adhered to the green sheet.

[0058] Next, the resulting laminate of green sheet and metal film was fired. The firing was carried out in a reducing atmosphere using a hydrogen-nitrogen gas mixture, with a maximum temperature of 930°C and a holding time of 2 hours.

[0059] Next, the copper foil of the resulting fired body was etched to obtain a predetermined shape. This etching process was carried out using conventional methods. This resulted in obtaining the wiring board of sample 1.

[0060] <Sample 2> The metal film and wiring substrate of Sample 2 were obtained using the same method and conditions as for Sample 1, except that in the metal film fabrication process, borosilicate glass powder with an average particle size of 1 μm was used instead of nano-sized silica particles.

[0061] <Sample 3> In the metal film fabrication process, the metal film and wiring substrate of Sample 3 were obtained using the same method and conditions as for Sample 1, except that nano-sized silica particles were attached to the copper foil with an organic resin adhesive.

[0062] <Various evaluations> Next, the metal films and wiring boards of samples 1 to 3 obtained above were visually observed. As a result, in the metal film of sample 1, the silica particles were firmly attached to the copper foil, and the silica particles did not detach from the copper foil even when the metal film was handled. In the metal film of sample 1, the silica particles were bonded to the copper foil by electrostatic force and van der Waals force.

[0063] Furthermore, the metal films and wiring boards of samples 1 to 3 obtained above were cut, the cut surfaces were filled with resin, and then mirror-polished. The cross-sections were then observed using a scanning electron microscope (SEM). As a result, in the metal film of sample 1, multiple silica particles were observed that were firmly bonded to the copper foil by neck bonds.

[0064] Furthermore, in the wiring board of sample 1, silica particles were present in particulate form between the copper foil and the glass ceramics, and the silica particles were bonded to the glass ceramics. In the wiring board of sample 1, the area around the neck bonding portion of the silica particles was filled with glass ceramics.

[0065] Thus, in the wiring board of sample 1, by using nano-sized silica particles as a binder for the copper foil, solid solution into the glass ceramics was suppressed, while the silica particles remained firmly bonded to the copper foil in a particulate state.

[0066] On the other hand, in the wiring board of sample 2, the glass powder was solid-dissolved on the insulating layer side, and was hardly present in granular form between the copper foil and the glass ceramics.

[0067] Furthermore, the presence or absence of conductor delamination in the wiring boards of samples 1 to 3 obtained above was evaluated. For evaluation, copper foil was laid on both sides of an insulating layer with sides of 10 mm to 50 mm.

[0068] Furthermore, to evaluate conductor delamination, the evaluation sample was first cut at a point approximately half the length in one direction, and both the interface between the insulating layer and the copper foil at the cross-section were observed. If delamination was observed in even one location, it was judged as "delamination present," and if no delamination was observed at any interface, it was judged as "no delamination."

[0069] In the above determination, the condition "peeling present" was defined as a state where the length of the area where the insulating layer and the copper foil are separated by 0.1 mm or more was 1 mm or more. As a result, the wiring board of sample 1 was determined to have "no peeling," while the wiring boards of samples 2 and 3 were determined to have "peeling present."

[0070] Furthermore, the interfacial conductivity of the wiring boards of samples 1 to 3 obtained above was measured. The interfacial conductivity was measured using the dielectric cylindrical resonator method shown below. For the measurement, a sample with a diameter of 50 mm and copper foil formed on almost the entire surface of both sides was used.

[0071] The dielectric cylinder resonator method is a method for measuring interfacial conductivity by forming a dielectric resonator by attaching an insulating layer with a conductor formed inside to one or both ends of a dielectric cylinder made of a dielectric material with known relative permittivity and dielectric loss, in a predetermined relationship, thereby measuring the conductivity at the interface between the copper foil and the insulating layer, i.e., the conductor interface.

[0072] The principle of this measurement method is that when an electromagnetic field resonator is constructed by sandwiching a dielectric cylinder having a predetermined dimensional ratio (height h / diameter d) between two sufficiently large conducting plates (usually conducting plates with a diameter D about three times the diameter d of the dielectric cylinder) positioned parallel to each other, the high-frequency current flowing through the conducting plates due to the TEomn resonant mode (hereinafter referred to as the TEomn mode) is distributed only on the short-circuit surface, i.e., the surface facing the dielectric and the conductor.

[0073] In dielectric resonators, the high-frequency current flowing through a conductor due to TEomn modes (m=1,2,3..., n=1,2,3...) is distributed only at the interface between the conductor and the dielectric substrate in contact with the dielectric cylinder. By utilizing this distribution, the interface conductivity can be calculated from the measured resonant frequencies f0 of the TEomn modes (m=1,2,3..., n=1,2,3...), no-load Q, and Qu. The interface conductivity was measured in the frequency range of 1 (GHz) to 49 (GHz) and evaluated as a relative value with the interface conductivity in DC set to 100 (%).

[0074] As a result, the interface conductivity of the wiring board of sample 1 was 80% or higher in the frequency range of 1 GHz to 49 GHz. On the other hand, the interface conductivity of the wiring boards of samples 2 and 3 was 80% in the frequency range of 1 GHz to 49 GHz.

[0075] Furthermore, the wiring boards of samples 1 to 3 obtained above were subjected to a thermal shock resistance test by immersing them in a heated solder bath for approximately 1 second. In this thermal shock resistance test, the temperature of the solder bath was set to two temperatures: 325°C (i.e., ΔT = 300°C) and 355°C (i.e., ΔT = 330°C).

[0076] Furthermore, cracks in the wiring boards were confirmed by observing samples of the wiring boards, which had been cross-polished, using a stereomicroscope. As a result, the wiring board of sample 1 showed good thermal shock resistance at all temperatures, while the wiring boards of samples 2 and 3 did not show good thermal shock resistance at any temperature.

[0077] While embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications are possible without departing from its spirit. For example, the above embodiments show an example in which fine silica powder is attached to a metal foil 10, but the present disclosure is not limited to such an example.

[0078] For example, a ceramic fine powder other than silica (such as alumina fine powder) may be attached to the metal foil 10. This also provides the same effects as the embodiment described above.

[0079] Further effects and other embodiments can be readily derived by those skilled in the art. Therefore, broader embodiments of this disclosure are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents.

[0080] Furthermore, this technology can also be configured as follows. (1) Metal foil and Multiple silica particles with an average particle size of 100 nm or less, Equipped with, Multiple silica particles are in contact with the surface of the metal foil. Metal film. (2) An electrostatic attraction is acting between the metal foil and the silica particles. The metal film described in (1) above. (3) The silica particles are spherical and are in point contact with the metal foil. In the aforementioned metal foil, the parts that are not in contact with the silica particles are left exposed. The metal film described in (1) or (2) above. (4) In a plan view, when the unit area of ​​the metal foil is set to 1, the area ratio of the multiple silica particles is 1% or more and 60% or less. A metal film as described in any one of (1) to (3) above. (5) The aforementioned metal foil contains copper or nickel as its main component. A metal film as described in any one of (1) to (4) above. (6) The silica particles are aggregates of multiple primary particles having an average particle size of 1 nm or more and 5 nm or less. A metal film as described in any one of (1) to (5) above. (7) A metal film as described in any one of (1) to (6) above, Insulating layer and, Equipped with, The metal foil is bonded to the insulating layer via a plurality of silica particles. Electronic components. (8) The aforementioned metal foil is composed of at least one type of metal foil selected from the group including copper foil such as electrolytic copper foil and rolled copper foil, nickel foil, and composite foil made by layering these metal foils. The electronic components described in (7) above. (9) The surface roughness of the metal foil is 0.001 μm or more and 0.5 μm or less. The electronic component described in (7) or (8) above. (10) The particle size range of the silica particles is such that, when the particle size distribution is measured, the range from D10 (10% integrated) to D90 (90% integrated) is 5 nm or more and 50 nm or less. An electronic component as described in any one of (7) to (9) above. (11) The silica particles are present at the interface between the metal foil and the insulating layer. An electronic component as described in any one of (7) to (10) above. (12) Within the surface of the silica particles, there are portions with a curvature greater than that estimated from the average radius of the silica particles, and the region where such portions with high curvature are in contact with the metal foil forms a surface with a predetermined area. An electronic component as described in any one of (7) to (11) above. (13) The silica particles are dispersed planarly at the interface between the insulating layer and the metal foil. An electronic component as described in any one of (7) to (12) above. (14) The silica particles are dispersed without overlapping on the main surface of the metal foil. An electronic component as described in any one of (7) to (13) above. (15) Among the silica particles, some particles have a neck portion between them and the metal foil. An electronic component as described in any one of (7) to (14) above. [Explanation of symbols]

[0081] 1 Metal film 2. Wiring board (an example of electronic components) 10 Metal foil 10a Main surface (an example of a surface) 11 Silica particles 12 Insulating layer 12a Main surface

Claims

1. Metal foil and Multiple silica particles with an average particle size of 100 nm or less, Glass ceramics and, Equipped with, Multiple silica particles are in contact with the surface of the metal foil. The metal foil is bonded to the glass ceramic via a plurality of silica particles. Electronic components.

2. An electrostatic attraction is acting between the metal foil and the silica particles. The electronic component according to claim 1.

3. The silica particles are spherical and are in point contact with the metal foil. In the aforementioned metal foil, the parts that are not in contact with the silica particles are left exposed. The electronic component according to claim 1 or 2.

4. In a plan view, when the unit area of ​​the metal foil is set to 1, the area ratio of the plurality of silica particles is 1% or more and 60% or less. The electronic component according to claim 1 or 2.

5. The aforementioned metal foil contains copper or nickel as its main component. The electronic component according to claim 1 or 2.

6. The silica particles are aggregates of multiple primary particles having an average particle size of 1 nm or more and 5 nm or less. The electronic component according to claim 1 or 2.

7. The aforementioned metal foil is composed of at least one type of metal foil selected from the group consisting of copper foil, nickel foil, and composite foils made by layering these metal foils. The electronic component according to claim 1 or 2.

8. The surface roughness of the metal foil is 0.001 μm or more and 0.5 μm or less. The electronic component according to claim 1 or 2.

9. The particle size range of the silica particles is such that, when the particle size distribution is measured, the range from D10 (10% cumulative) to D90 (90% cumulative) is 5 nm or more and 50 nm or less. The electronic component according to claim 1 or 2.

10. The silica particles are present at the interface between the metal foil and the glass ceramics. The electronic component according to claim 1 or 2.

11. Within the surface of the silica particles, there are portions with a curvature greater than that estimated from the average radius of the silica particles, and the region where such portions with high curvature are in contact with the metal foil forms a surface with a predetermined area. The electronic component according to claim 1 or 2.

12. The silica particles are dispersed planarly at the interface between the glass ceramic and the metal foil. The electronic component according to claim 1 or 2.

13. The silica particles are dispersed without overlapping on the main surface of the metal foil. The electronic component according to claim 1 or 2.

14. Among the silica particles, some particles have a neck portion between them and the metal foil. The electronic component according to claim 1 or 2.

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