Alkali developable solder resist, cured product of the same and printed wiring board obtained using the same

Abstract

Disclosed is an alkaline development-type solder resist which is a composition developable with a dilute alkali solution and comprises the following components (A) to (D): (A) a photosensitive resin having a carboxyl group, which is produced by reacting a compound (a) having two or more cyclic ether groups or cyclic thioether groups in the molecule with an unsaturated monocarboxylic acid (b), reacting the resulting product with a polybasic acid anhydride (c) to produce a resin, reacting the resin with a compound (d) having both of a cyclic ether group and an ethylenically unsaturated group in the molecule, and reacting the resulting product with the polybasic acid anhydride (c) again; (B) an oxime ester-type photopolymerization initiator having an oxime ester group which is represented by the general formula (I); (C) a compound having two or more ethylenically unsaturated groups in the molecule; and (D) a thermocurable component. When the solder resist is formed into a dried coating film, the coating film has an absorbance of 0.3 to 1.2 at a wavelength of 350 to 375 nm per 25 [mu]m film thickness. In the chemical formula (I) R<1> represents a hydrogen atom, an alkyl group having 1 to 7 carbon atoms or a phenyl group; and R<2> represents an alkyl group having 1 to 7 carbon atoms or a phenyl group.

Description

technical field [0001] The present invention relates to an alkali-developing type solder resist useful for the manufacture of printed wiring boards, its cured product, and printed wiring boards obtained by using the same. Alkali-developing type solder resist obtained by curing with a light source, its cured product, and a printed circuit board obtained by using the same. Background technique [0002] A solder resist film is formed on the outermost layer of a printed wiring board of an electronic device. Solder resist refers to a protective coating material that prevents unnecessary solder from adhering to the circuit surface when covering the surface of a printed circuit board, coating with solder, and mounting components. Furthermore, it is a protective film that protects the copper foil circuit of the printed wiring board as a permanent protective mask from the perspective of humidity, dust, etc., and at the same time, has the function of an insulator to protect the circu...

AI Technical Summary

Problems solved by technology

However, although it is true that these technologies can exhibit sufficient photopolymerization ability even under single-wavelength rays such as 355nm and 405nm, due to the very high photopolymerization speed, deep curing and surface curing cannot be obtained at the same time. Significant reduction in sensitivity due to deactivation of the photopolymerization initiator on the circuit, and there is a problem of peeling on the copper circuit

[0007] In addition, since direct drawing image formation using a laser is usually carried out in an air atmosphere, an inhibition reaction by oxygen is likely to occur, and in the developing process of removing unnecessary parts after exposure, the surface part of the resist part that is necessary is removed. , as a result, there is a problem of easily causing poor gloss

Furthermore, in the solder resist for the purpose of protecting a printed wiring board, poor gloss not only causes a problem of poor appearance, but also has a problem of insufficient reaction of the part that should originally react, resulting in poor chemical resistance on the surface of the film, and furthermore The problem that the characteristics are also poor

[0008] In addition, a photocurable resin with increased photosensitive group density and excellent photocurability has also been proposed (for example, Patent Document 3), although it cannot be used for direct laser imaging, but this is the status quo

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