Abstract: A watertight structure for a spliced portion includes a container that has an open top adapted to receive a spliced portion of electrical wires and that is elongated in a longitudinal direction of the electrical wires, and a lid to be mounted on the container. The container is provided with a bottom wall and upward inclined portions that extend in a longitudinal direction. The container is provided with a spliced portion positioning section having a narrow width. The spliced portion positioning section is provided on opposite outer sides with receiving portions to be engaged with locking pieces projecting from the lid.

Abstract: A watertight structure for a spliced portion includes a container 14 that has an open top 14g adapted to receive a spliced portion 13 of electrical wires and that is elongated in a longitudinal direction X of the electrical wires W1 and W2, and a lid 15 to be mounted on the container. The container is provided with a bottom wall 14a including a central flat portion 14a-1 at a deepest position in the container and upward inclined portions 14a-2 that extend from opposite sides of the central flat portion in a longitudinal direction. The central flat portion is provided with a spliced portion positioning section 14c having a narrow width. The spliced portion positioning section is provided on opposite outer sides with receiving portions 14f to be engaged with locking pieces 15d projecting from opposite sides of the lid. The lid is provided on a middle part in the longitudinal direction with a narrow width portion 15a adapted to be fitted in the spliced portion positioning section.

Abstract: Low-thermal-expansivity polyimides have a linear rigid skeleton, so that adhesion between perfectly cured low-thermal-expansivity polyimide films is very low. On the other hand, a film of a polyimide having a flexible skeleton shows high adhesiveness even after perfect curing, so that it is possible to enhance adhesion between the low-thermal-expansivity polyimide films by interposing a polyimide having a flexible skeleton. A flexible polyimide thin film is formed as a highly adhesive film on a low-thermal-expansivity polyimide film in a half-cured state, then metallic wiring is applied thereon, followed by formation of another highly adhesive thin film in a half-cured state, and then a low-thermal-expansivity polyimide film is further formed thereon. It is possible to provide a multilayer wiring structure which has improved adhesion between the low-thermal-expansivity polyimide film and the wiring pattern layer or the substrate.

Abstract: A process of forming a patterned polyimide film includes the step of conversion of a polyimide precursor into polyimide. The improvement is imidizing the precursor by means of a chemical imidizing reagent. Typically a film of polyimide precursor is formed on a substrate, and mask which is negative with respect to the desired pattern is formed on the film. The film is contacted through the mask with a chemical imidizing reagent to effect imidization of unmasked portions, thereby forming polyimide. The mask and masked portions of the film are removed, leaving the desired polyimide pattern. High temperatures and harmful etchants can be avoided.

Abstract: An acid dianhydride complex which is characterized in anti-hydrolysis, good stability, and high solubility in an organic solvent, is prepared by a reaction of a basic organic compound having a donor number of at least 20 and being free from an active hydrogen atom in the molecule and a carboxylic dianhydride compound.

Abstract: The present invention provides a process for producing a metal-polyimide composite material such as a wiring board. In production thereof, deterioration of polyamide film due to oxidation during imidization of a polyimide precursor in contact with metal such as copper or silver can be prevented. The present invention is characterized by using a polyimide precursor having an acidic functional group which is masked. Examples of the polyamide precursor are polyamic acid epoxy adducts, amido polyamic acids, silylated polyamic acids, etc.

Abstract: A 10 to 50 microns thick apertured foil is coated on at least one of its sides with a material having a thickness of about 10 to 100 microns. The atomic number of the coating material is such that characteristic X-rays generated are effectively absorbed.