An electronic circuit includes: a motherboard; an input/output connector including at least one group containing N input/output contacts; a set containing expansion slots having expansion contacts electrically connected to input/output contacts; each input/output contact being identified by an identifier T, each expansion slot being identified by an identifier S, each connected expansion contact being identified by an identifier R, for: each expansion slot of identifier S; and each connected expansion contact of identifier R. Each input/output contact of identifier T is electrically connected to a single expansion contact of identifier R of the expansion slot of identifier S, and the identifier T is calculated according to the following relation: T?[(R+D?S) modulo (N)], where D is fixed in each group and is an integer sub-multiple of the natural number N.

A multilayer board includes a flexible base material including laminated insulator layers and curved along an X-axis direction on a plane orthogonal or substantially orthogonal to a lamination direction, an interlayer connection conductor on the flexible base material, and a notch pair on the flexible base material at positions symmetrical or substantially symmetrical in the X-axis direction with respect to a position of the interlayer connection conductor, the notch pair extending in a Y-axis direction orthogonal or substantially orthogonal to the X-axis direction on the plane. The interlayer connection conductor is within a region defined by the notch pair and lines respectively joining ends of the notch pair in the Y-axis direction. A radius of curvature of a region of the flexible base material between the notch pair in the X-axis direction being greater than curvature radii of regions outside of the notch pair.

A universal circuit board compatible for a mechanical keyswitch and an optical keyswitch includes a main body, a plurality of conductive terminals and an opening structure. The main body has a first surface and a second surface opposite to each other. The plurality of conductive terminals is disposed on the first surface of the main body. The opening structure is formed on the main body and pierces through the first surface and the second surface. The opening structure can be inserted by an axle body of the mechanical keyswitch or be an optical transmission channel of the optical keyswitch.

A method of forming an multi-chip carrier that includes providing a trace structure using an additive forming method. The method includes forming a metal layer on a trace structure to provide electrically conductive lines. A dielectric material may then be formed on the electrically conductive lines to encapsulate a majority of the electrically conductive lines. The ends of the electrically conductive lines that are exposed through the upper surface of the dielectric material provide a top processor mount location and the ends of the electrically conductive lines that are exposed through the sidewalls of the dielectric material provide a sidewall processor mount location.

An anisotropic electrically conductive film includes electrically conductive particles disposed in an electrically insulating adhesive layer. The particles are arranged at a predetermined pitch along first axes, arranged side by side, and are substantially spherical. The particle pitch at the first axes and the axis pitch of the first axes are both greater than or equal to 1.5D, D being an average particle diameter of the particles. Directions of all sides of a triangle formed by a particle (P0), which is one of the electrically conductive particles at one of the first axes, an electrically conductive particle (P1), which is at the one of the first axes and adjacent to the particle (P0), and an electrically conductive particle (P2), which is at another one of the first axes that is adjacent to the one of the first axes, are oblique to a film width direction of the conductive film.

A resin multilayer substrate includes a substrate main body including first, second, and third wiring portions connected to one another by a connecting portion. First, second and third external connection terminals are respectively included in the first, second and third wiring portions. The first external connection terminal includes a conductor exposed at a surface of the substrate main body. The second and third external connection terminals include connectors mounted on conductors on the surface of the substrate main body. An auxiliary mounting conductor is disposed between the first external connection terminal and the second and third external connection terminals on the surface of the substrate main body.

A rip stop material is attached at a stress area of a flexible circuit board in order to strengthen the flexible circuit board and minimize ripping and cracking in the polyimide and/or the copper conductors of the circuit. A rip stop transition layer is formed and deposited at a location on the flexible circuit in order to minimize, reduce, if not preventing cracking and ripping of the circuit as it is bent and flexed. The rip stop transition layer can be placed at different locations on and within the flexible circuit in order to minimize cracking and ripping as the flexible circuit is bent, flexed and twisted.

A universal circuit board compatible for a mechanical keyswitch and an optical keyswitch includes a main body, a plurality of conductive terminals and an opening structure. The main body has a first surface and a second surface opposite to each other. The plurality of conductive terminals is disposed on the first surface of the main body. The opening structure is formed on the main body and pierces through the first surface and the second surface. The opening structure can be inserted by an axle body of the mechanical keyswitch or be an optical transmission channel of the optical keyswitch.

A circuit substrate module includes: a plurality of substrates which are arranged in a matrix, and on at least some of which circuit components are mounted; a plurality of first flexible substrates each of which is arranged between two adjacent substrates in a row direction among the plurality of substrates, and connects the two adjacent substrates; and a plurality of second flexible substrates each of which is arranged between two adjacent substrates in a column direction among the plurality of substrates, and connects the two adjacent substrates.

A connector for enabling an electrical connection between principal surfaces of two planar panels by being sandwiched between the two planar panels. The connector comprises a deformable main body having a first elongated cuboid shape and having, perpendicular to the longitudinal direction of the first elongated cuboid shape, a first rectangular cross-section, and a conductive layer fully enclosing the perimeter of the first rectangular cross-section along a portion of the longitudinal direction of the deformable main body.