摘要:
A multi-layer flexible circuit board has multiple thicker regions to which components are mounted and thinner, more flexible regions with fewer wiring layers through which the board can be bent about a line without bending thicker regions. Surface mount components such as QFP's and flip-chips are mounted on the front side, and surface mount and pin-in-hole components are mounted on the back side of the circuit board at the thick regions. Heat spreaders are laminated to the back sides of thicker regions. The thicker regions have windows in which wire bond chips are mounted on the heat spreader and wire bonded to the front side of the board. A thermally conductive adhesive or grease connects between the tops of the back side components and the bottoms of the cavities. The heat sinks are bolted together and/or to an enclosure frame to improve thermal performance.
摘要:
A screen printing fixture holds a flexible circuit board having components attached to one side, to allow screening a pattern of solder paste onto the second side for subsequent attachment of components to that side. In an electronic package assembly a flexible circuit board with components is wound about a heat spreader assembly having a cavity so that at least one component on the flexible circuit board is positioned within the cavity and in thermal connection to the heat spreader.
摘要:
A multi-layer flexible circuit board has thicker regions to which surface-mount-technology (SMT) components (such as flip chips and QFPs) and pin-in-hole (PIH) components are mounted on both sides and which contains conductive through vias between wiring layers. After the SMT components have been mounted to the first side, a screening fixture with a support surface that has cavities conforming the components on the first side, is used to screen solder paste to the other side of the board. The thicker regions are surrounded by thinner regions of the board with fewer wiring layers and preferably fewer or thinner dielectric layers, and which can be bent along a line without bending the thicker regions. A common heat spreader plate with cavities or holes for multiple components is laminated to the thicker regions on one side of the board. The thicker regions have windows in which wire-bond chips are mounted to the heat spreader and the chips are wirebonded to the other side of the board. A thermally conductive adhesive or grease connects between the components and the bottoms of the cavities. Two heat sink plates are bolted together and along with other such heat sink plates are bolted to an enclosure frame to improve thermal performance.
摘要:
A screen printing machine comprising a backing plate with holes conforming to components attached to the surface of a flexible circuit board. The machine includes a screen which patterns solder paste on the surface of the circuit board while the circuit board is on the backing plate. Also included is a spring loaded element disposed adjacent to the backing plate which applies a predetermined continuous force to the four corners of the circuit board. This force is applied in a diagonal direction to the corners to stretch the circuit board so that the circuit board is parallel to the backing plate during screening.
摘要:
A suspension of a coating material having hydrogen bonds and pre-determined physical and chemical characteristics in a predominantly solid state in a polar solvent that is capable of breaking the hydrogen bonds and providing the material in a liquid form and use of the suspension to provide substantially uniform conformal layer of material onto a workpiece by applying the suspension to a workpiece and then evaporating the polar organic solvent so that the coating material is provided in its predominantly solid state having substantially the predetermined physicall and chemical characteristics.