Abstract:
A method of forming a subassembly for use in a printed circuit board is described. This method includes providing a subassembly including a circuit board layer laminated to two sheets of conductive material with two intermediate sheets of prepreg material, forming a via in the assembly, plating the via, filling the via with a plug material in a volatile solvent, evaporating the volatile solvent, and curing the plug material. Also described is a method of forming a partially filled via in a circuit board layer and a method of forming a thermally conductive plug in a circuit board layer for the transfer of thermal energy from one surface of the circuit board to the other.
Abstract:
An apparatus for manufacturing a plug and the manufacturing method. The method includes the following steps. A baseplate located in the bottom of a closed printing chamber is provided. A printed circuit board and a stencil are mounted on the baseplate in sequence. The stencil is aligned to the printed circuit board. An amount of preheated paste is placed on the stencil. A pressure of the closed printing chamber is adjusted to a first pressure. A printing step is performed to form plugs in the printed circuit board. The pressure of the closed printing chamber is adjusted to a second pressure to remove voids trapped in the plugs. The pressure of the closed printing chamber is adjusted to a third pressure. A scraping step is performed to remove the redundant paste.
Abstract:
A method provides for additive plating on a subcomposite having filled plated through holes. Fine-line circuitry is achieved via electroless deposition onto a dielectric substrate after the through hole is plated and filled. Fine-line circuitry may be routed over landless, plated through holes thereby increasing the aspect ratio and the available surface area for additional components and wiring.
Abstract:
An electronic device comprising a semiconductor chip which is fixed to the mounting face of a wiring board through an adhesive and in which external terminals are electrically connected with electrode pads of the wiring board through bump electrodes. Recesses are formed in the electrode pads, and in the recesses the electrode pads and the bump electrodes are connected. The electrode pads are formed over the surface of a soft layer, and the recesses are formed by elastic deformation of the electrode pads and the soft layer.
Abstract:
A ball-grid array connector structure for an electronic package in which the ball pitch can be reduced to increase the packaging density has a plastic substrate having at least one hollow through-hole and an electrode covering the wall of the through-hole and forming an electrode pad surrounding the through-hole on each surface of the substrate. A metallic ball is joined, either directly or through a solder or a combination of a metallic bump and a solder, to the electrode pad on at least one surface of the substrate at the position of the through-hole. The connector structure can be formed either by sealing an open end of the through-hole on the side to which the ball is not joined, or increasing the pressure within the through-hole by a pressure-control mechanism, before the through-hole is blocked by reflowing the ball itself or the metallic bump or solder used to connect the ball.
Abstract:
An electronic component is mounted on a substrate such as a circuit board by means of a soldering process such as reflow soldering. The circuit board has a thermal via hole therethrough to provide a heat dissipation path from the top surface to the bottom surface of the circuit board, for dissipating heat from the electronic component. To prevent molten solder from penetrating through the via hole during the soldering process, the via hole is sealed prior to the soldering process. The via hole is sealed from the bottom surface of the substrate by carrying out a screen printing process including at least two printing passes to print a sealing material into the open hole of the thermal via.
Abstract:
A liquid thermosetting filling composition comprising (A) an epoxy resin assuming a liquid state at room temperature, (B) a phenolic resin assuming a liquid state at room temperature, (C) a curing catalyst, and (D) an inorganic filler is useful as an ink for permanently filling such holes as via holes and through holes in printed circuit boards of a multilayer board or a double-sided board, a sealing compound for IC packages, and the like. This composition is a two-stage thermally curing type. In a method for permanently filling holes in a printed circuit board, the composition is applied to the board so as to fill the holes in the printed circuit board and precured by application of heat. The parts of the precured composition protruding from a surface defining the holes is removed by polishing and then the precured composition is further heated to cause final curing thereof.
Abstract:
A method for forming a planarized thin film dielectric film on a surface of a common circuit base upon which one or more integrated circuits are to be attached. The common circuit base includes raised features formed over its surface such that the raised features define a trench area between them. The method includes the steps of forming a first layer of the dielectric film over the common circuit base and over the raised features and the trench, then patterning the newly formed layer to remove portions of the layer formed over the raised features and expose the raised features. After the layer is patterned, formation of the dielectric film is completed by forming a second layer of the dielectric film over the patterned first layer. Additional film deposition and film patterning steps are performed to complete the layout of a thin film interconnect structure over said common circuit base, and an integrated circuit die is attached to the common circuit base and electrically connecting to the thin film interconnect structure. In a preferred embodiment, the first and second layers of the dielectric film are both formed from a photo-definable material and the patterning step includes exposing the first layer to light through a patterned mask corresponding to the raised features and developing the exposed layer with a developing solution to etch away portions of the first layer formed over the raised features.
Abstract:
A process for manufacturing circuit boards comprising providing a circuitized substrate having a dielectric surface, providing a peel apart structure including a metal layer and a peelable film, laminating the peel apart structure to the circuitized substrate with the metal layer positioned adjacent said dielectric surface, forming holes in the circuitized substrate through the peel apart structure, applying a filler material including an organic base to the peel apart structure, applying a sacrificial film onto the filler material, and applying sufficient heat and pressure to the sacrificial film to force the filler material into the holes to substantially fill the holes is provided.
Abstract:
A method of making a circuitized substrate such as a printed circuit board having at least one hole therein which comprises the steps of providing a layer of dielectric, forming at least one (and preferably several) holes therein, providing a fill member including a quantity of fill material and reinforcement means located within the fill material, positioning the fill member on the dielectric over the holes and thereafter applying a predetermined force sufficient to cause only the fill material to be forcibly driven into the accommodating hole(s), not the reinforcement means. Subsequent steps can include forming a layer of circuitry on the substrate's external surface and over the filled holes such that an electrical component such as a ball grid array (BGA), semiconductor chip, etc. may be directly positioned on and/or over the hole(s). A fill member usable with the method is also provided.