Abstract:
A soldering member for connection to an external unit, which is joined to a connection terminal having a nickel/gold electroless plating layer on the surface formed correspondingly to a conductor pattern on a printed wiring board. The member comprises a soldering ball containing finely powdered copper, and exhibits excellent strength of junction to the connection terminal.
Abstract:
A method of testing and mounting electronic components that are to be surface-mounted. The components include on one side a plurality of contact pads that shall be connected electrically to contact pads on one side of a test board, particularly BGA components and corresponding components. The invention is characterized by applying to the component contact pads (2) a metal (5) which is liquid at room temperature or at an elevated room temperature, in a first method step; lifting the component (1) away from the surface of the metal (5) in a second method step, wherewith part (7) of the liquid metal remains on the component contact pads (2); and bringing the component contact pads (2) provided with the liquid metal into abutment with corresponding contact pads (3) on the test board (4), in a third method step.
Abstract:
A connective medium for use in ball grid arrays for connecting electronic devices to circuit boards comprising high melting point solder alloy spheres (32) coated, by electroplating, with an outer concentric layer of a lower melting point solder alloy (34) of uniform thickness. In a further aspect, a leach barrier (30) is coated on the high melting point solder alloy (32) prior to electroplating the low melting point solder alloy (34) thereto. The leach barrier (30) forms a barrier to prevent the lead from leaching from the high melting point lead solder spheres (32) into the low melting point solder alloy (34) during the reflow heat treatment in the mounting process.
Abstract:
A housing (10) in which a connection support (12) for an integrated circuit (11) includes an insulating film (13) with conductors (14) on one side and, on the other side, balls (15) connected to respective conductors via lead-throughs (16) and directly fixed in said lead-throughs, the bottom walls of the lead-throughs being formed by the respective conductors. The balls are preferably made of a remeltable material such as tin-lead and fastening may at first be achieved using an adhesive substance. The method for connecting two connection supports (12, 22) via balls (15), where one support includes a film (13) with conductors (14) on one side and lead-throughs (16) on the other side, comprises directly fixing the balls to the conductors in the lead-throughs by remelting the balls. The balls may be welded or attached in advance by means of an adhesive substance to the connection pads (23) of the board (22).
Abstract:
A dual solder layer for fluidic self assembly, an electrical component substrate, and method employing same is described. The dual solder layer comprises a layer of a self-assembly solder (12) disposed on a layer of a base solder (14) which is disposed on the solder pad (16) of an electrical component substrate(18). The self-assembly solder (12) has a liquidus temperature less than a first temperature and the base solder (14) has a solidus temperature greater than the first temperature. The self-assembly solder (12) liquefies at the first temperature during a fluidic self assembly method to cause electrical components (10) to adhere to the substrate (18). After attachment, the substrate(18) is removed from the bath (20) and heated so that the base solder (14) and self-assembly solder (12) combine to form a composite alloy (22) which forms the final electrical solder connection between the component (10) and the solder pad (16) on the substrate (18).
Abstract:
Method for assembling a semiconductor device having fatigue-resistant interconnection fillet provides a semiconductor chip with at least one solder bump comprising an alloy of tin and lead with a melting temperature higher than the solder paste used. Further, a solder paste (preferably binary) is provided, which comprises tin and about 2.5 weight percent silver, and has a melting temperature of about 221 °C. The solder bump is brought in contact with the solder paste (803), the bump is partially immersed in the paste (804), and thermal energy is supplied to reflow the solder paste at about 235 °C (805). The amount of energy and time after the reflow of the paste is controlled so that the molten paste dissolves a pre-determined amount of the solder bump (lead and tin) to form a ternary alloy of about eutectic composition (about 1.62 weight % Ag, 36.95 weight % Pb, 61.43 weight % Sn) without melting the solder bump (806).