JP-7854637-B2 - Adhesive structure and adhesive method

Inventors

• 小泉 剛
• 古川 勝紀
• 小嶋 直人
• 谷田貝 朋紀
• 小林 靖之
• 池田 慎吾
• 中谷 真大

Assignees

• 株式会社電子技研
• 地方独立行政法人大阪産業技術研究所

Dates

Publication Date

20260507

Application Date

20220202

Claims (6)

1. An adhesive structure comprising a first substrate, a second substrate, and an adhesive interposed between these substrates, One or both of the first substrate and the second substrate are poorly bonded materials consisting of PS (polystyrene), PPS (polyphenylene sulfide), PEEK (polyether ether ketone), PEN (polyethylene naphthalate), PET (polyethylene terephthalate), or metal. A first functional group is present bonded to a dangling bond formed on the surface of the first substrate. A second functional group is present bonded to microcracks formed on the surface of the second substrate. The adhesive has a third functional group, With the third functional group interposed between the first and second functional groups, at least a portion of the first and second functional groups are bonded by covalent bonds or hydrogen bonds, so that at least a portion of the first or second functional group and the third functional group are bonded to each other without reacting. An adhesive structure characterized in that the first functional group and the second functional group are -NHx.
2. The adhesive structure according to claim 1, characterized in that the third functional group is at least one of -H, -NHx, -COOH, -C=O, -OH, -F, or -CFx.
3. The adhesive structure according to claim 1 or 2, characterized in that one of the first substrate and the second substrate is made of copper, ceramic, or gold, and the functional groups are formed on its surface by plasma treatment, and at least a portion of the functional groups and the functional groups contained in the epoxy adhesive or silicone adhesive are bonded to each other without reacting.
4. The adhesive structure according to any one of claims 1 to 3, wherein the adhesive has a relative permittivity Dk of 3.0 or less.
5. The adhesive structure according to any one of claims 1 to 4, wherein the adhesive has a glass transition temperature Tg of 250°C or higher.
6. A bonding method for bonding a first substrate and a second substrate by interposing an adhesive between them, One or both of the first and second substrates are made of poorly bondable materials such as PS (polystyrene), PPS (polyphenylene sulfide), PEEK (polyether ether ketone), PEN (polyethylene naphthalate), PET (polyethylene terephthalate), or metal. Plasma treatment is used to form a dangling bond on the surface of the first substrate, and the first functional group is bonded to the dangling bond. Microcracks are formed on the surface of the second substrate by plasma treatment, and the second functional group is bonded to the microcracks. The third functional group of the adhesive is interposed between the first functional group and the second functional group. By bonding at least a portion of the first functional group and the second functional group by covalent bonds or hydrogen bonds, at least a portion of the first functional group or the second functional group and the third functional group are bonded together without reacting with each other, and the surfaces of the first substrate and the second substrate are bonded together via the adhesive. A bonding method characterized in that the first functional group and the second functional group are -NHx.

Description

This invention relates to an adhesive structure and adhesive method for bonding different or identical substrates. For example, in the manufacturing processes of various products such as printed circuit boards, semiconductor substrates, touch panels, liquid crystal substrates, sporting goods, and stationery, there are processes that involve bonding the same or different types of substrates, and adhesives are often used in such processes. One reason for using adhesive is that when bonding different types of substrates, directly bonding them can cause stress due to differences in thermal expansion coefficients, potentially leading to cracking of the substrates. By interposing an adhesive between the substrates, the adhesive acts as a buffer, preventing such cracking. In this case, if the base material is a difficult-to-bond material such as Teflon, or if the adhesive has a low dielectric constant or high heat resistance, the adhesive strength between the surface of the base material and the adhesive will be weak, which can lead to defects in the resulting product. Therefore, conventionally, when using the aforementioned difficult-to-bond substrates or adhesives, pretreatment is performed to improve the adhesive strength between the substrate surface and the adhesive. This pretreatment typically involves using highly toxic or special chemical solutions such as metallic sodium ammonia water or permanent magnesium acid. However, the aforementioned highly toxic and specialized chemicals have a significant environmental impact due to their use and wastewater, and given the various environmental protection demands of recent times, it is expected that their continued use will become increasingly difficult. On the other hand, as a method for bonding two substrates without using adhesive, there is a method, for example, as shown in Patent Document 1, in which -OH groups are generated on the surface of a fluororesin sheet by plasma treatment, and this surface of the fluororesin sheet is then bonded to a metal member. However, the actual adhesive strength obtained through functional group reactions, such as dehydration condensation by -OH groups, is not particularly strong. For example, sufficient adhesive strength has not been achieved for difficult-to-bond substrates like Teflon. Patent No. 5152784 A schematic diagram showing the configuration of the plasma processing apparatus according to this embodiment.A flowchart illustrating the procedure for the bonding method in the same embodiment.A conceptual diagram showing the configuration of the adhesive structure in the same embodiment.A conceptual diagram showing the bonding configuration of functional groups in the same embodiment.X-ray analysis results of the adhesive structure in the same embodiment.A conceptual diagram illustrating the evaluation of the adhesive strength of the adhesive structure in the same embodiment.The results of X-ray analysis of the PTFE film before the addition of functional groups in the same embodiment.The results of X-ray analysis of the PTFE film after the addition of functional groups in the same embodiment.A conceptual diagram showing the configuration of the adhesive structure in other embodiments. An adhesive structure and adhesive method according to one embodiment of the present invention will be described with reference to the drawings. <Device configuration> First, let me describe the equipment used to manufacture adhesive structures. This apparatus is a plasma processing apparatus 100 for plasma treatment of a substrate surface. As shown in Figure 1, it comprises a vacuum chamber 1, a lower electrode 2 provided within the vacuum chamber 1 to support the substrate W, an upper electrode 3 positioned opposite the substrate W within the vacuum chamber 1, and a high-frequency power supply 4. The apparatus is configured to generate plasma P within the vacuum chamber 1 by supplying high-frequency power from the high-frequency power supply 4 to the lower electrode 2 (for example, 13.50 MHz) and grounding the upper electrode 3. Furthermore, depending on the substrate material, the type of reaction gas, etc., this plasma processing apparatus 100 is configured to switch to a method where the lower electrode 2 is grounded and high-frequency power is supplied to the upper electrode 3. In this embodiment, the plasma processing apparatus 100 is used to generate functional groups on the surface of the substrate W, and a process gas G corresponding to the functional groups to be generated is supplied into the vacuum chamber 1 under reduced pressure of 0.1 to 10,000 Pa. <Adhesion method> Next, the procedure for bonding a first substrate and a second substrate of different or the same type using an adhesive, with reference to the flowchart in Figure 2 and the conceptual diagram in Figure 3, will be explained using the plasma processing apparatus described above. The first and second substrates are, for example, flat plates, and specifically, they