A polyimide film is a reaction product of a diamine component and an acid dianhydride component. The diamine component contains p-phenylenediamine, a first aromatic diamine, and a second aromatic diamine. The first aromatic diamine and the second aromatic diamine are different from each other and represented by the following formula (1):

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In the diamine component, each of a molar fraction of the p-phenylenediamine, a molar fraction of the first aromatic diamine, and a molar fraction of the second aromatic diamine is 10% by mole or more and 70% by mole or less. The acid dianhydride component contains an acid dianhydride containing an aromatic ring.

A polyimide film is a reaction product of a diamine component and an acid dianhydride component. The diamine component contains p-phenylenediamine, a first aromatic diamine, and a second aromatic diamine. The first aromatic diamine and the second aromatic diamine are different from each other and represented by the following formula (1):

##STR00001##

In the diamine component, each of a molar fraction of the p-phenylenediamine, a molar fraction of the first aromatic diamine, and a molar fraction of the second aromatic diamine is 10% by mole or more and 70% by mole or less. The acid dianhydride component contains an acid dianhydride containing an aromatic ring.

A substrate for a printed wiring board includes a base layer, and a copper foil directly or indirectly stacked on at least a part of one or both surfaces of the base layer. The base layer includes a matrix containing a fluororesin as a main component and one or more reinforcing material layers included in the matrix, and a ratio B/A is 0.003 to 0.37, where A is an average thickness of the base layer, and B is an average distance between a surface of the copper foil facing the matrix and a surface of a reinforcing material layer closest to the surface of the copper foil facing the copper foil.

A substrate for a printed wiring board includes a base layer, and a copper foil directly or indirectly stacked on at least a part of one or both surfaces of the base layer. The base layer includes a matrix containing a fluororesin as a main component and one or more reinforcing material layers included in the matrix, and a ratio B/A is 0.003 to 0.37, where A is an average thickness of the base layer, and B is an average distance between a surface of the copper foil facing the matrix and a surface of a reinforcing material layer closest to the surface of the copper foil facing the copper foil.

A circuit board 1 including: a substrate; an electrode pad on a surface of the substrate; and a projecting electrode on the electrode pad, wherein the electrode pad on which the projecting electrode is disposed is larger than the projecting electrode when viewed from above, and a coating layer covers at least a portion of an outer periphery of the electrode pad on which the projecting electrode is disposed.

In manufacturing a printed circuit board using a semi-additive method, a removal liquid that has been used in removing a nickel-chromium-containing layer (5) is regenerated by contacting the removal liquid with a chelate resin having a functional group represented by a following formula (1) :

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where a plurality of Rs are identical divalent hydrocarbon groups having 1 to 5 carbons, and a portion of hydrogen atoms may be substituted with halogen atoms.

A sintered body includes a crystal grain containing silicon nitride, and a grain boundary phase. If dielectric losses of the sintered body are measured while applying an alternating voltage to the sintered body and continuously changing a frequency of the alternating voltage from 50 Hz to 1 MHz, an average value ε.sub.A of dielectric losses of the sintered body in a frequency band from 800 kHz to 1 MHz and an average value ε.sub.B of dielectric losses of the sintered body in a frequency band from 100 Hz to 200 Hz satisfy an expression |ε.sub.A−ε.sub.B|≤0.1.

A sintered body includes a crystal grain containing silicon nitride, and a grain boundary phase. If dielectric losses of the sintered body are measured while applying an alternating voltage to the sintered body and continuously changing a frequency of the alternating voltage from 50 Hz to 1 MHz, an average value ε.sub.A of dielectric losses of the sintered body in a frequency band from 800 kHz to 1 MHz and an average value ε.sub.B of dielectric losses of the sintered body in a frequency band from 100 Hz to 200 Hz satisfy an expression |ε.sub.A−ε.sub.B|≤0.1.

In an x-ray source, an isolation circuit can isolate bias voltage at a cathode from a bias voltage at an alternating current source (AC source). The isolation circuit can transfer alternating current from the AC source to the cathode. The isolation circuit can be made repeatedly with minimal variation or failed parts, can be light, and can be small. The isolation circuit can include planar transformer(s). Each planar transformer can include a primary trace on a primary circuit board and a secondary trace on a secondary circuit board. The primary trace and the secondary trace can each include a spiral shape. The primary trace can be located in close proximity to the secondary trace such that alternating electrical current through the primary trace will induce alternating electrical current through the secondary trace.

A resin composition for a printed wiring board, including: a phenolic compound (A); a maleimide compound (B); an epoxy compound (C); a cyclic carbodiimide compound (D); an inorganic filler (E); and a curing accelerator (F), wherein a content of the inorganic filler (E) is 100 to 250 parts by mass based on 100 parts by mass of a resin solid content.