Abstract: Herein disclosed is a noncontact, nondestructive method for monitoring the quality of a high energy weld, e.g., laser beam weld. In accordance with the proposed method, an acoustic sensor (32) is positioned at a distance from the welding zone (34) and picks up airborne acoustic emission signals (33) associated with the laser welding process. These acoustic signals, propagating through the air space between the welding zone (34) and the sensor (32), are detected and analyzed (36,37) to determine the quality of the weld (FIG. 3).

Abstract: An automatic pull tester and an acoustic emission system are herein combined to analyze the failure modes of lead frames bonded to integrated circuits. By using a discriminant analysis technique, a specific failure mode can be determined in real-time by first measuring up to five variables during the pulling operation. The five variables that may be measured comprise acoustic emission signals of a first amplitude (AE1), acoustic emission signals of a second amplitude (AE2), the time elapsed until failure (.DELTA.t), the number (n) of acoustic emission bursts above a first threshold, to the peak pulling force at failure (L.sub.max). Next, the variables measured are incorporated into a plurality of predetermined functions, each function corresponding to one failure mode (FM1 to FM5). The failure mode of the bond is determined by selecting the function having the highest value (FIG. 4).

Abstract: The attachment of leadless chip carriers to printed wiring boards by means of soldering techniques must provide for a spacing between the chip carrier and the board. Such spacing is required for cleaning the area under the chip carrier, protecting the underlying circuitry, and accounting for stresses which may develop due to thermal mismatch between the chip carrier and the board, and to board flexure. Herein disclosed is a lead (15) for semiconductor chip carriers comprising an elongated body of high melting point electrically conductive material, e.g., solder material. Also disclosed is a method for casting such a solder lead, and a method for attaching a plurality of cast solder leads (38) to a leadless chip carrier (20).

Abstract: In the manufacture of integrated circuits, it is often necessary to prepare dielectrically-isolated single-crystal silicon regions to be used as substrates in which various circuit elements may be formed. These regions or substrates are formed by attaching a single-crystal silicon wafer (1) having a dielectrically-coated surface (2) to a second single-crystal silicon wafer (3) by means of an intermediate metallic layer (4) positioned therebetween. Using a heating process, e.g., a thermomigration process also referred to as temperature gradient zone-melting (TGZM) technique, the metallic layer (4) is removed through the second silicon wafer (3). This method substantially eliminates any bending or warpage of the dielectrically-isolated substrate (FIG. 1).

Abstract: A pulse generator comprises a toroid (11) of a superconducting material such as Niobium on a glass or ceramic substrate (12). A cryogenic source such as liquid helium cools the toroid to within a few degrees of absolute zero and a perpetually circulatory current is set up in the toroid. A laser beam is fired at the toroid to cause localized heating and the resultant current drop due to the material resistance causes an output pulse to be induced in an adjacent current winding (14).

Abstract: The architecture of a conventional digital computer, for example, a microprocessor, is modified by interposing a multiplexer (31), a logic array (32) and a demultiplexer (33) between the instruction register (17) and instruction decoder (18). The logic array "scrambles" the bits in each instruction code; however, if the program to be run is priorly encrypted with this "scrambling" in mind, it will run normally. On the other hand, if the encrypted program is copied, the copied program will not run on an unmodified computer.

Abstract: An electromechanical resonator, in the form of a single planar body, comprises a flexurally vibrating resonating element coupled at its midplane to a pair of torsionally vibrating couplers. Unwanted flexural modes in the resonator are substantially reduced by selecting a length-to-width ratio of the resonating element ranging between 3 and 4. A bandpass filter comprising a plurality of such electromechanical resonators may operate essentially free of spurious responses over a band of at least 200 kHz.

Abstract: An apparatus for stabilizing microwave oscillator circuits is disclosed. The apparatus comprises a dielectric resonator positioned in the vicinity of a microwave semiconductive device for completing a feedback path between two electrode circuits of the device. A dielectric spacer is positioned between the resonator and the electrodes for supporting the resonator and controlling the magnitude of coupling between the two electrode circuits. A folded mechanical structure is described wherein the oscillating device and the resonator are located at the fold for improving the frequency stability of the oscillator. The microwave semiconductive device may be a bipolar transistor or a field effect transistor.