JP-7856966-B2 - Primer composition for electroless plating, laminate, and method for manufacturing the same.

Inventors

• 小山 太一
• 中辻 達也

Assignees

• 三井化学株式会社
• 株式会社イオックス

Dates

Publication Date

20260512

Application Date

20220304

Claims (10)

1. A phenoxy resin (A) with an epoxy equivalent of 5000 g/eq or more , The phenoxy resin (A) comprises 25 to 65 parts by mass of melamine resin (B) per 100 parts by mass of the phenoxy resin (A), Primer composition for electroless plating.
2. Phenoxy resin (A) and The phenoxy resin (A) is mixed with 25 to 65 parts by mass of melamine resin (B) per 100 parts by mass, Epoxy resin (C) and Includes resolphenol resin (D), Primer composition for electroless plating.
3. The total amount of the epoxy resin (C) and the resolphenol resin (D) is 30 to 80 parts by mass per 100 parts by mass of the phenoxy resin (A). The electroless plating primer composition according to claim 2.
4. The epoxy resin (C) is a polyfunctional epoxy resin having three or more epoxy groups in its molecule. The electroless plating primer composition according to claim 2 or 3.
5. The epoxy resin (C) is a solid epoxy resin. A primer composition for electroless plating according to any one of claims 2 to 4.
6. Phenoxy resin (A) and The phenoxy resin (A) is mixed with 25 to 65 parts by mass of melamine resin (B) per 100 parts by mass, Including a palladium catalyst, Primer composition for electroless plating.
7. Further containing silica particles, The electroless plating primer composition according to claim 6.
8. Insulating substrate and A primer layer disposed on the insulating substrate, comprising a cured product of the electroless plating primer composition according to any one of claims 1 to 7, The primer layer includes a metal plating layer disposed on the primer layer, Laminated structure.
9. The insulating substrate includes a low dielectric constant resin selected from the group consisting of polyimide, polyetheretherketone, cyclic polyolefin, polyphenylene sulfide, liquid crystalline polymer, and fluororesin. The laminate according to claim 8.
10. A step of applying the electroless plating primer composition according to any one of claims 1 to 7 to the surface of an insulating substrate, and then drying and curing it to form a primer layer, The process includes forming a metal plating layer on the primer layer by electroless plating. A method for manufacturing laminates.

Description

This invention relates to a primer composition for electroless plating, a laminate, and a method for producing the same. The technique of forming metal plating on insulating substrates such as resin substrates is used in the manufacture of conductive films for electromagnetic wave seals, decorative plating for aesthetic purposes, and electronic components such as integrated circuits and resistors. In particular, when manufacturing printed circuit boards used in electronic equipment, this plating technique is utilized when forming conductive wiring patterns on insulating substrates. In this process, to improve adhesion between the insulating substrate and the plating layer, etching (roughening) the surface of the insulating substrate to create fine irregularities is being considered to impart an anchoring effect. However, this etching not only complicates the process, but also presents a problem in high-frequency devices for 5G, where the skin effect tends to increase transmission loss. In response to this, methods are being investigated for bonding the insulating substrate and the plating layer without etching. For example, a method is known in which an underlayer (primer layer) containing an electroless plating catalyst is formed on the surface of the insulating substrate, and then the plating layer is formed (see Patent Document 1). Japanese Patent Publication No. 2013-209643 The inventors investigated the composition of a primer composition that can cure well in a short time and impart a cured product with high coating strength, and found that a combination of phenoxy resin (A) and melamine resin (B) is effective. Furthermore, they found that by adjusting the content of melamine resin (B) within a predetermined range, good reactivity and adhesion to electroless plating solutions can also be maintained. The reason for this is not entirely clear, but it is speculated as follows: Phenoxy resin (A) not only has a tough structure but also contains many hydroxyl groups in its molecule. Therefore, the hydroxyl groups of phenoxy resin (A) react with the methylol groups of melamine resin (B), etc., to form a high-density crosslinked structure, resulting in a cured product with high surface hardness. On the other hand, if the amount of melamine resin (B) is too high, the surface hardness of the cured product becomes too high, making it difficult for the palladium catalyst, which acts as a reaction nucleus with the electroless plating solution, to be exposed on the surface, or making it difficult to stably retain the palladium catalyst when it is applied to the cured product of the primer composition, thus impairing the reactivity of the electroless plating solution. Furthermore, if the cured product becomes too hard, its adhesive properties are also easily impaired. In contrast, by appropriately adjusting the content of melamine resin (B), a cured product with appropriate strength can be obtained, thereby suppressing the above-mentioned problems. Such a primer composition is suitable for processes that form plating films using roll-to-roll methods. Furthermore, by adding epoxy resin (C) and resolphenol resin (D) to the above components, the adhesion of the cured primer composition can be further enhanced. Specifically, the methylol hydroxyl groups or phenolic hydroxyl groups of resolphenol resin (D) react with the epoxy groups of epoxy resin (C), not only facilitating the curing of epoxy resin (C), but also generating hydroxyl groups during the reaction process (ring-opening reaction). This is believed to effectively improve adhesion to the insulating substrate. The composition of the primer composition of the present invention will be described in detail below. 1. Primer Composition The primer composition of the present invention comprises a phenoxy resin (A) and a melamine resin (B). 1-1. Phenoxy resin (A) Phenoxy resin (A) is a polymer having a polyhydroxypolyether structure obtained by polyaddition reaction of polyfunctional phenols and polyfunctional glycidyl ethers (preferably bisphenols and epichlorohydrin). The weight-average molecular weight (Mw) of phenoxy resin (A) is typically 10,000 to 200,000, preferably 20,000 to 100,000, and more preferably 30,000 to 80,000. When the Mw of phenoxy resin (A) is above a certain level, a cured primer composition with high coating strength is easily obtained. When it is below a certain level, the viscosity of the primer composition does not increase excessively, and handling is not easily impaired. The Mw of phenoxy resin (A) can be determined by performing gel permeation chromatography (GPC) using tetrahydrofuran (THF) as the solvent, and expressed as a value equivalent to standard polystyrene. The secondary hydroxyl group equivalent of phenoxy resin (A) is not particularly limited, but is preferably 240 g/eq or more, more preferably 250 to 290 g/eq. When the secondary hydroxyl group equivalent of phenoxy resin (A) is within the above range, it contains a large number