Circuit board
The circuit board design with annular silver particles surrounding glass particles addresses the challenge of maintaining conductivity and bonding by reducing electrical resistance and contact resistance, ensuring efficient electrode performance.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NITERRA CO LTD
- Filing Date
- 2024-12-19
- Publication Date
- 2026-07-01
AI Technical Summary
Existing technologies face challenges in achieving good conductivity while ensuring proper bonding between electrodes and substrate bodies, as the presence of glass in electrodes tends to increase electrical resistance.
A circuit board design incorporating electrodes made of silver particles with annular silver particles surrounding glass particles, where the glass particles are exposed on the surface in an area ratio of 10% or less, and annular silver particles form grain boundaries with other silver particles, creating a conductive path with low electrical resistance.
The design ensures effective bonding with the substrate body and maintains good conductivity by reducing contact resistance and electrical resistance, enhancing overall electrode conductivity.
Smart Images
Figure 2026108956000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a circuit board.
Background Art
[0002] Conventionally, a composition according to a purpose has been produced by mixing a plurality of materials. For example, Patent Document 1 discloses the production of a paste composition containing hollow glass, metal particles, and an organic vehicle for the purpose of forming a porous body. Further, Patent Documents 2 and 3 disclose the production of a lightweight noble metal sintering composition obtained by kneading noble metal powder, hollow glass, and an organic binder for the purpose of weight reduction.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Patent Document 2
Patent Document 3
Summary of the Invention
Problems to be Solved by the Invention
[0004] In a paste composition produced for the purpose of forming an electrode, glass may be added to improve the bonding property between the electrode and the substrate body on which the electrode is disposed. However, while the bonding property is improved by the presence of glass in the electrode, the electrical resistance value tends to increase. For this reason, there has been a demand for a technology that can realize an electrode having good conductivity while ensuring bonding to the substrate body. Note that Patent Documents 1 to 3 do not consider at all the compatibility between bonding to the substrate body and good conductivity.
[0005] The present invention has been made to solve at least some of the above-mentioned problems, and aims to provide a circuit board equipped with electrodes that have good conductivity while ensuring proper bonding with the substrate body. [Means for solving the problem]
[0006] The present invention has been made to solve at least some of the above-mentioned problems and can be realized in the following forms.
[0007] (1) According to one embodiment of the present invention, a circuit board is provided. This circuit board comprises a substrate body and an electrode disposed on the substrate body and containing silver particles and glass particles, wherein the surface of the electrode contains annular silver particles surrounding the glass particles.
[0008] This configuration includes glass particles in the electrodes to improve bonding between silver particles and between silver particles and the substrate body. Since some of these glass particles are surrounded by annular silver particles, the increase in electrical resistance due to the presence of glass particles between silver particles can be suppressed. Therefore, a circuit board is provided that has electrodes that ensure good conductivity while also ensuring proper bonding with the substrate body.
[0009] (2) In the circuit board according to the above embodiment, the area ratio of the portion on the surface in which the glass particles are exposed may be 10% or less. With this configuration, the proportion of the surface area where glass particles are exposed on the electrode surface is relatively low, which reduces the contact resistance at the contact surface when other conductors come into contact with the circuit board via the electrode. Therefore, good conductivity can be ensured between the electrode and other conductors.
[0010] (3) In the circuit board according to the above embodiment, the annular silver particles may form grain boundaries with other silver particles on the surface. In this configuration, the annular silver particles are in contact with other silver particles, thus ensuring a conductive path through the annular silver particles. Because conduction is possible with low electrical resistance through such a conductive path without passing through glass particles, this leads to improved conductivity throughout the electrode. Therefore, this configuration can improve the conductivity of the electrode.
[0011] Furthermore, the present invention can be realized in various forms, for example, in the form of a circuit board, electronic components, IC package (LTCC), sensor device, semiconductor device, and a system comprising these, as well as a method for manufacturing a circuit board and a system comprising these. [Brief explanation of the drawing]
[0012] [Figure 1] This is a perspective view of a circuit board according to an embodiment of the present invention. [Figure 2] This is an explanatory diagram of the paste used in the electrode formation process. [Figure 3] This is an explanatory diagram showing the state of silver particles and glass particles contained in the electrode. [Figure 4] This is an explanatory diagram showing an image of the electrode surface. [Figure 5] This is an explanatory diagram showing a magnified image of the framed area. [Figure 6] This is a schematic diagram of annular silver particles as seen in a magnified image. [Figure 7] This is an explanatory diagram showing an image of the surface of the electrode in the comparative example. [Figure 8] This is an explanatory diagram showing an image of the surface of the electrode in the comparative example. [Modes for carrying out the invention]
[0013] <Embodiment> FIG. 1 is a perspective view of a circuit board 1 according to an embodiment of the present invention. The circuit board 1 is a plate-like member on which electronic components are mounted. The circuit board 1 includes a substrate body 10 and electrodes 20. In FIG. 1, only the substrate body 10 and the electrodes 20 are shown as the configuration of the circuit board 1. Of course, the circuit board 1 may have a configuration different from the substrate body 10 and the electrodes 20.
[0014] The substrate body 10 is a plate-like member formed of a ceramic material or a glass-ceramic material in which a glass component is mixed with the ceramic material. Examples of the ceramic material include aluminum oxide (Al2O3), aluminum nitride (AlN), silicon nitride (Si3N4), and the like. The electrodes 20 are disposed on the substrate body 10. Here, above the substrate body 10 refers to the surface of the substrate body 10. The electrodes 20 contain silver particles and glass particles.
[0015] FIG. 2 is an explanatory view of a paste PS used in the formation process of the electrodes 20. The paste PS is prepared by adding silver particles AG and glass particles GL to a resin solvent SV obtained by mixing a resin and a solvent. At this time, the glass particles GL added to the resin solvent SV have a melting point lower than that of the silver particles AG and are hollow glass containing bubbles. The electrodes 20 are formed by applying the paste PS on the substrate body 10 and then sintering the paste PS at 900°C. 900°C is a temperature not exceeding the melting point of the silver particles AG and not lower than the melting point of the hollow glass. During this sintering, since the resin solvent SV vaporizes, the electrodes 20 contain almost no resin solvent SV and mainly contain silver particles AG and glass particles GL (see FIG. 3 described later). The amounts of the silver particles AG and the glass particles GL added to the paste PS before sintering are adjusted so that the volume percentage of the silver particles AG in the electrodes 20 after sintering is about 80 vol% and the volume percentage of the glass particles GL is about 20 vol%.
[0016] Figure 3 is a schematic diagram illustrating the state of silver particles AG and glass particles GL contained in electrode 20. When paste PS (Figure 2) is sintered, the glass particles GL undergo a volume reduction. The voids created by this volume reduction are filled by the softened silver particles AG during sintering, increasing the contact points between the silver particles AG and lowering the overall electrical resistance of electrode 20. Furthermore, the softened silver particles AG exist as particles of various sizes and shapes. Therefore, during sintering, entanglement between silver particles AG and between silver particles AG and glass particles GL easily occurs, resulting in close contact between particles and the formation of a dense electrode 20. It is presumed that the volume occupied by silver particles AG is large in the overall electrode 20. In addition, the size of the glass particles GL in electrode 20 is smaller than the majority of the silver particles AG of various sizes. Electrode 20 also contains both glass particles GL containing air bubbles (hollow glass) and glass particles GL without air bubbles.
[0017] Figure 4 is an explanatory diagram showing an image of the surface of electrode 20. The image shown in Figure 4 was acquired using a scanning electron microscope (SEM). The area of the surface of electrode 20 in which glass particles GL are exposed is 10% or less. The area of the surface of electrode 20 in which glass particles GL are exposed can be confirmed by image analysis of images acquired using a scanning electron microscope (SEM) as shown in Figure 4. The frame FR in Figure 4 will be explained next.
[0018] FIG. 5 is an explanatory diagram showing an enlarged image of a portion of the frame FR. FIG. 6 is a schematic diagram of the annular silver particles CP shown in the enlarged image of FIG. 5. The annular silver particles CP are a type of silver particles AG and surround the glass particles GL. Specifically, the glass particles GL are surrounded by one silver particle AG. In other words, no grain boundary is formed between the outer edge OG and the inner edge IG of the annular silver particles CP. Thus, in the circuit board 1, the surface of the electrode 20 contains annular silver particles CP surrounding glass. Also, as shown in FIG. 6, on the surface of the electrode 20, such annular silver particles CP form grain boundaries with other silver particles AG. The confirmation of the presence of the annular silver particles CP on the surface of the electrode 20 and the confirmation of the formation of grain boundaries between the annular silver particles CP and other silver particles AG are confirmed by taking five images of the surface of the electrode 20 included in a field of view of 100 μm × 100 μm with a scanning electron microscope (SEM). Specifically, if the annular silver particles CP are present in one or more of the five captured images, and a state where the annular silver particles CP form grain boundaries with one or more other silver particles AG is shown, it is considered that the annular silver particles CP are present on the surface of the electrode 20 and grain boundaries are formed between the annular silver particles CP and other silver particles AG.
[0019] Figure 7 is an explanatory diagram showing an image of the surface of electrode 20a of the comparative example. Figure 8 is an explanatory diagram showing an image of the surface of electrode 20b of the comparative example. Electrode 20a shown in Figure 7 is manufactured using the same molding process as electrode 20, except that the glass particles GL added to the resin solvent SV during the molding process are not hollow glass. Electrode 20b shown in Figure 8 is manufactured using the same molding process as electrode 20, except that the temperature at which the paste PS is sintered during the molding process is 800°C. Annular silver particles CP could not be observed on the surfaces of electrode 20a and electrode 20b of the comparative example. Therefore, it is considered that the fact that the glass particles GL added to the resin solvent SV are hollow glass, and that the temperature at which the paste PS is sintered is 900°C, contributes to the formation of annular silver particles CP. Furthermore, it was confirmed that the resistivity value of electrode 20 in which such annular silver particles CP are observed on the surface is lower than that of electrode 20a and electrode 20b. In other words, since the glass particles GL within the cyclic silver particles CP are surrounded by the cyclic silver particles CP (silver particles AG), it is thought that the increase in electrical resistance due to the presence of glass particles GL between the silver particles AG is suppressed.
[0020] According to the circuit board 1 of the embodiment described above, the electrode 20 includes glass particles GL that improve bonding between silver particles AG and between silver particles AG and the substrate body 10, and since a portion of the glass particles GL is surrounded by annular silver particles CP, the increase in electrical resistance due to the presence of glass particles GL between silver particles AG can be suppressed. Therefore, a circuit board 1 is provided that has electrodes 20 that ensure bonding with the substrate body 10 while also having good conductivity.
[0021] Furthermore, in the circuit board 1 of this embodiment, the area of the surface of the electrode 20 where the glass particles GL are exposed is 10% or less. Therefore, since the area of the surface of the electrode 20 where the glass particles GL are exposed is relatively low, the contact resistance at the contact surface when another conductor comes into contact with the circuit board 1 via the electrode 20 can be reduced. Thus, good conductivity can be ensured between the electrode 20 and the other conductor.
[0022] Furthermore, in the circuit board 1 of this embodiment, the annular silver particles CP form grain boundaries with other silver particles AG on the surface of the electrode 20. Therefore, since the annular silver particles CP and other silver particles AG are in contact, a conductive path is secured through the annular silver particles CP. In such a conductive path, conduction is possible with a low electrical resistance without passing through the glass particles GL, which leads to an improvement in the conductivity of the electrode 20 as a whole. Thus, the circuit board 1 of this embodiment can improve the conductivity of the electrode.
[0023] <Modified form of this embodiment> The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit, for example, the following modifications are also possible.
[0024] In the above embodiment, the amounts of silver particles AG and glass particles GL added to the paste PS before sintering were adjusted so that the volume percentage of silver particles AG in the electrode 20 after sintering was approximately 80 vol% and the volume percentage of glass particles GL was approximately 20 vol%, but this is not limited to this. For example, as long as annular silver particles CP are included on the surface of the electrode 20 after sintering, the amounts of silver particles AG and glass particles GL added to the paste PS before sintering may be adjusted so that the volume percentage of silver particles AG in the electrode 20 after sintering is not approximately 80 vol% and the volume percentage of glass particles GL is not approximately 20 vol%.
[0025] In the above embodiment, the area ratio of the portion of the electrode 20 surface where glass particles GL are exposed was 10% or less, but it is not limited to this. For example, as long as the surface of the electrode 20 after sintering contains annular silver particles CP, the area ratio of the portion of the electrode 20 surface where glass particles GL are exposed may be 10% or more by changing points other than the fact that the glass particles GL added to the resin solvent SV during the electrode 20 formation process are hollow glass and the temperature when sintering the paste PS is 900°C. Of course, from the viewpoint of ensuring good conductivity between the electrode 20 and other conductors, it is preferable that the area ratio of the portion of the electrode 20 surface where glass particles GL are exposed is 10% or less.
[0026] In the above embodiment, on the surface of the electrode 20, the cyclic silver particles CP formed grain boundaries with other silver particles AG. However, the cyclic silver particles CP may also form grain boundaries with other cyclic silver particles CP.
[0027] The embodiments of this specification have been described above based on the embodiments and modifications described above. The embodiments described above are for the purpose of facilitating understanding of this specification and do not limit it. This specification may be modified and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in this specification. Furthermore, any technical features that are not described as essential in this specification may be deleted as appropriate. [Explanation of symbols]
[0028] 1…Circuit board 10...Main board 20...Electrode AG…Silver particles CP... cyclic silver particles GL...glass particles IG...common-law marriage OG...outer edge PS... Paste SV… Resin solvent
Claims
1. A circuit board, The main circuit board and The substrate body is disposed on the aforementioned substrate and comprises an electrode containing silver particles and glass particles, A circuit board characterized in that the surface of the electrode contains annular silver particles surrounding the glass particles.
2. A circuit board according to claim 1, A circuit board characterized in that the area ratio of the portion on the surface in which the glass particles are exposed is 10% or less.
3. A circuit board according to claim 1 or claim 2, A circuit board characterized in that, on the aforementioned surface, the annular silver particles form grain boundaries with other silver particles.