A first embodiment of a substrate for a high-frequency printed wiring board according to the present disclosure is directed to a substrate for a high-frequency printed wiring board, the substrate including: a dielectric layer including a fluororesin and an inorganic filler; and a copper foil layered on at least one surface of the dielectric layer, wherein a surface of the copper foil at the dielectric layer side has a maximum height roughness (Rz) of less than or equal to 2 ?m, and a ratio of the number of inorganic atoms of the inorganic filler to the number of fluorine atoms of the fluororesin in a superficial region of the dielectric layer at the copper foil side is less than or equal to 0.08.

A fluororesin composition containing a melt moldable fluororesin and a silica, wherein the fluororesin has 25 or more carbonyl group-containing functional groups per 10.sup.6 main-chain carbon atoms; the silica is a spherical silica; and the fluororesin composition has a linear expansion coefficient of 100 ppm/? C. or lower. Also disclosed is a fluororesin sheet including the fluororesin composition, a laminate including a copper foil layer and a layer including the fluororesin composition and a substrate for circuits including a copper foil layer and a layer including the fluororesin composition.

Provided are a polyphenyl ether resin composition and a prepreg and a laminated board containing same. The polyphenyl ether resin composition comprises the following components: (1) a tetrafunctional or higher multifunctional acrylate-modified thermosetting polyphenyl ether resin; and (2) a vinyl resin cross-linking agent, the weight of the vinyl resin cross-linking agent being 40-100 parts by weight based on 100 parts by weight of the tetrafunctional or higher multifunctional acrylate-modified thermosetting polyphenyl ether resin. The modified thermosetting polyphenyl ether resin, due to containing a tetrafunctional or higher multifunctional acrylate active group, can cross-link more vinyl resin cross-linking agents. Not only the prepared high-speed electronic circuit substrate has low dielectric constant and dielectric loss, but also double bonds in side chains of the vinyl resin cross-linking agent are reacted completely in a resin curing system, so that the high-speed electronic circuit substrate has a better thermo-oxidative aging resistance.

Provided is an epoxy resin composition having excellent adhesion and low dielectric characteristics. Specifically, provided is an epoxy resin composition comprising an acid-modified polyolefin resin and an epoxy resin having a specific structure.

A method for coating a thermoplastic polymer substrate, the polymer including but not limited to a fluoropolymer such as polytetrafluoroethylene (PTFE), comprises forming a first layer of a first material on a surface of the substrate by cold spraying particles of the first material onto the surface of the thermoplastic substrate, and forming a second layer of a second material on a surface of the first layer, opposite to the substrate, by applying and adhering the second material onto to the first layer. A layered thermoplastic polymer substrate is also provided. Such layered thermoplastic substrates are well suited for use as flexible electronic circuits, as well as other electronic circuits applications.

(1) A conductor layer is disposed on at least one surface of a dielectric layer, the dielectric layer including an intermediate layer and a pair or more of fluororesin layers disposed on both surfaces of the intermediate layer, in which the ratio of the total average thickness of the intermediate layer to the total average thickness of the fluororesin layers is 0.001 to 30, the relative dielectric constant of the intermediate layer is 1.2 to 10, the coefficient of linear expansion of the intermediate layer is 110.sup.4/ C. to 510.sup.5/ C., and the adhesive strength between the fluororesin layer and the conductor layer is 300 g/cm or more. (2) Conductor layers are disposed on both surfaces of a dielectric layer made of a fluororesin, in which at least one of the conductor layers constitutes a wiring pattern, the average trace width of the wiring pattern is 25 to 300 m, the average thickness of the dielectric layer in the region where traces of the wiring pattern are disposed is 5 to 125 m, and the ratio of the average trace width to the average thickness of the dielectric layer is 2.4 to 30. (3) A multilayer structure includes conductor layers and dielectric layers made of a fluororesin alternately disposed, in which the fluororesin of the dielectric layers is crosslinked and chemically bonded to the conductor layers, the average thickness of the multilayer structure is 30 to 2,000 m, and the crush resistance of the multilayer structure measured by a loop stiffness test is 0.1 to 20,000 N/cm.

A first embodiment of a substrate for a high-frequency printed wiring board according to the present disclosure is directed to a substrate for a high-frequency printed wiring board, the substrate including: a dielectric layer including a fluororesin and an inorganic filler; and a copper foil layered on at least one surface of the dielectric layer, wherein a surface of the copper foil at the dielectric layer side has a maximum height roughness (Rz) of less than or equal to 2 ?m, and a ratio of the number of inorganic atoms of the inorganic filler to the number of fluorine atoms of the fluororesin in a superficial region of the dielectric layer at the copper foil side is less than or equal to 0.08.

Tamper-respondent assemblies and methods of fabrication are provided which include a tamper-respondent electronic circuit structure. The tamper-respondent electronic circuit structure includes a tamper-respondent sensor. The tamper-respondent sensor includes, for instance, at least one flexible layer having opposite first and second sides, and circuit lines forming at least one resistive network. The circuit lines are disposed on at least one of the first or second side of the at least one flexible layer, and have a line width W.sub.l200 m, as well as a line-to-line spacing width W.sub.s200 m. In certain enhanced embodiments, the tamper-respondent sensor includes multiple flexible layers, with a first flexible layer having first circuit lines, and a second flexible layer having second circuit lines, where the first and second circuit lines may have different line widths, different line-to-line spacings, and/or be formed of different materials.

To provide a dielectric film which is excellent in dielectric properties and stability in the electric corrosion test and which is suitable for producing a high-precision printed board.

A roll film comprising a melt-processable fluororesin as the main component and having a thickness of from 1 to 100 ?m, the dimensional change rate of which is less than 1.0%, in terms of an absolute value, in each of MD and TD, when heated at 150? C. for 30 minutes and then cooled to 25? C., based on the dimension at 25? C.

A resin sheet that contains one or more kinds of resin materials and a liquid crystal polymer, wherein a weight of the liquid crystal polymer is less than a total weight of the one or more kinds of resin materials. The resin sheet has a thermal expansion coefficient in a plane direction smaller than a thermal expansion coefficient in the plane direction of a comparative resin sheet containing the one or more kinds of resin materials and not containing the liquid crystal polymer.