Provided is a double-sided circuit substrate being a laminate of: a composite material comprising a fluorine resin and a glass cloth; and a copper foil having a two-dimensional roughness Ra in a mat surface (a surface that comes in contact with the resin) of less than 0.2 μm. Ideally, a surface of the fluorine resin has an O content of at least 1.0%, as observed using ESCA.

A method for manufacturing a flexible printed circuit board includes preliminarily thermally deforming s substrate through heating, forming a circuit pattern with a conductive paste on the preliminarily thermally deformed substrate, and firing the circuit pattern. A flexible printed circuit board includes a substrate, and a circuit pattern formed by firing a conductive paste on a first surface of the substrate. The substrate is preliminarily thermally deformed and, thus, a shrinkage variation thereof before and after firing the conductive paste is zero. Dimensional stability when firing the circuit pattern printed with the conductive paste can be ensured, deterioration of adhesion between the circuit pattern and the substrate attributable to film deformation upon firing can be prevented, and stable adhesion of the circuit pattern can be maintained even after firing.

A method of forming a flexible electronic component includes treating a flexible fluoroelastomer substrate to increase the surface energy of the substrate to a specified surface energy. After the treatment, a layer of conductive material is printed with an inkjet printer onto the substrate. After the printing, an encapsulant layer comprising a fluoroelastomer is applied onto the substrate.

There is provided a method for forming an electrically conductive ultrafine pattern which has an excellent pattern cross-sectional shape is provided by a composite technique including a printing process and a plating process, and furthermore, by imparting excellent adhesion to each interface of a laminate including a plating core pattern, an electrically conductive ultrafine pattern which can be preferably used as a highly accurate electric circuit and a method for manufacturing the same are also provided. The method includes (1) a step of applying a resin composition to form a receiving layer on a substrate; (2) a step of printing an ink containing plating core particles by a reverse offset printing method to form a plating core pattern on the receiving layer; and (3) a step of depositing a metal on the plating core pattern formed in the step (2) by an electrolytic plating method.

A manufacturing method for printed circuit boards includes the steps of: a) inkjet printing a UV free radical curable inkjet ink on a substrate (2); b) UV curing the UV free radical curable inkjet ink on the inkjet printed substrate; and c) applying a thermal treatment on the UV cured inkjet printed substrate; wherein the UV free radical curable inkjet ink contains at least a colorant, a free radical photoinitiator; a difunctional monomer or oligomer and a polyfunctional monomer or oligomer; and 1 to 15 wt % of a silane compound according to Formula (I):

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wherein, the linking group L represents a CH.sub.2 group or an aliphatic chain having 2 to 10 carbon atoms optionally substituted in the aliphatic chain by a nitrogen or an oxygen; R1 represents a methoxy group; R2 and R3 independently represent a methoxy group or a C.sub.1- to C.sub.4-alkyl group; and R4 represents a functional group selected from the group consisting of an epoxy group, an amine group, a carbamate group, a trimethoxy silane group and an ureido group.

Provided are a method for forming a high-definition metal pattern which including the steps of (1) forming a receiving layer on a substrate by coating the substrate with a resin composition including a urethane resin having a weight-average molecular weight of five thousand or more or a vinyl resin and a medium, (2) forming a plating-core pattern on the receiving layer by printing an ink including a particle that serves as a plating core on the receiving layer by reverse offset printing, and (3) depositing a metal on the plating-core pattern by electroless plating, a high-definition metal pattern formed by the above-described method, and an electronic component including the high-definition metal pattern.