Abstract: Fixtures for attaching a semiconductor chip to a substrate. The semiconductor chip has an array of joining material bumps, such as C4 solder balls. The substrate has an array of conductive pads corresponding to the array of joining material bumps. In a first embodiment the fixture has a body having a first cavity for containing the semiconductor chip and a second cavity in communication with the first cavity for containing the substrate. Whereby the substrate is placed over the semiconductor chip with the conductive pads opposing and in contact with the joining material bumps, such that during reflow of the joining material bumps, the weight of the substrate acts against the joining material bumps and aids in the attachment of the semiconductor chip to the substrate to form electrical connections therebetween.

Abstract: An electrical structure, and associated method of fabrication, for reducing thermally induced strain in a structure that couples a first conductive body of a first substrate to a second conductive body of a second substrate (e.g., a chip to a chip carrier; a chip carrier to a circuit card). The melting point of the first conductive body exceeds the melting point of the second conductive body. The second conductive body may include eutectic lead-tin alloy, while the first conductive body may include non-eutectic lead-tin alloy. A portion of the first conductive body is coated with, or volumetrically surrounded by, a material that is nonsolderable and nonconductive. The first and second conductive bodies are coupled mechanically and electrically by surface adhesion at an uncoated portion of the first conductive body, by application of a temperature that lies between the melting points of the first and second conductive bodies.

Abstract: An encapsulated semiconductor chip module. The chip module has the overlying encapsulant adhered directly and integrally to bare portions of the substrate to which the chip is mounted. This configuration enhances the adhesion and inhibits unintended delamination of the encapsulant from the balance of the module. The module is made by patterning anchor openings into the solder mask. The anchor openings expose corresponding portions of the substrate. It is important to locate the anchor openings over parts of the substrate that do not have circuitry on them, that is, on bare portions, so as to avoid corrosion or contamination of the circuit connections.

Abstract: A method of forming a printed circuit board or circuit card is provided with a metal layer which serves as a power plane sandwiched between a pair of photoimageable dielectric layers. Photoformed metal filled vias and photoformed plated through holes are in the photopatternable material, and signal circuitry is on the surfaces of each of the dielectric materials and connected to the vias and plated through holes. A border may be around the board or card including a metal layer terminating in from the edge of one of the dielectric layers. A copper foil is provided with clearance holes. First and second layers of photoimageable curable dielectric material is disposed on opposite sides of the copper which are photoimageable material. The patterns are developed on the first and second layers of the photoimageable material to reveal the metal layer through vias. At the clearance holes in the copper, through holes are developed where holes were patterned in both dielectric layers.

Abstract: A new rework process for semiconductor chips mounted in a flip chip configuration, via solder balls, on an organic substrate is disclosed.