Raytheon

About: Raytheon is a company organization based out in Waltham, Massachusetts, United States. It is known for research contribution in the topics: Signal & Antenna (radio). The organization has 15290 authors who have published 18973 publications receiving 300052 citations.

Development of BGA solder joint vibration fatigue life prediction model

Abstract: The objective of the present study is to develop a vibration fatigue life prediction model for ball grid array (BGA) solder joint. In this study, 3D global/local finite element models were first constructed with MSC/PATRAN code. For the global model including BGA package soldered onto the printed wiring board (PWB), linear finite element dynamic analyses with an excitation normal to the PWB were conducted using MSC/NASTRAN code to determine the dynamic responses at the two ends of BGA solder joint. In these analyses, a single-degree-of-freedom system was assumed. A steady-state harmonic (or frequency sweep) response provides phase angle values while a random response furnishes the power spectral densities as well as their root mean square (RMS) values. For the local model having a refined mesh to simulate the local region in detail, a linear finite element static analysis was conducted by applying the derived RMS values with their corresponding phase angles to this model (at the two ends of the critical corner solder joint) in order to determine the solder effective stress/strain RMS value. A vibration fatigue life model, evolved from an empirically derived formula of universal slopes based on high-cycle fatigue test data, was established. This model combined with a three-band technique and the derived solder effective strain was then used to predict the BGA solder joint survivability/durability. This prediction will be compared to test results, which will be provided by in-house on-going R&D, to validate the proposed BGA solder joint vibration fatigue life prediction model. An example of a 600-pin plastic BGA soldered onto the various locations of the PWB was illustrated in the present study.

Reactor vessel for the growth of heterojunction devices

Abstract: A metalorganic chemical vapor deposition (MOCVD) reactor vessel is provided for the growth of Group II-VI, Group III-V, or Group IV layers particularly for use in thin heterostructure devices. The reactor vessel includes a chamber having a top surface substantially parallel to a semiconductor substrate disposed within the chamber and an inlet through which a vapor stream is directed. The chamber further includes a plate having a plurality of apertures disposed therethrough and a block disposed adjacent to the plate, to increase the uniformity and decrease the turbulence of the vapor stream.

The microwave Doherty amplifier

Abstract: A microwave Doherty amplifier has been designed using PHEMT devices in a novel configuration at L-band. Power-added efficiency of 61% is achieved at -1 dB gain compression in CW and is maintained at 61% at 5.5 dB back-off from the above point. The theory, design and measurement for this new amplifier are discussed. >

Radiated microwave power transmission system efficiency measurements

Abstract: The measured and calculated results from determining the operating efficiencies of a laboratory version of a system for transporting electric power from one point to another via a wireless free space radiated microwave beam are reported. The system's overall end-to-end efficiency as well as intermediated conversion efficiencies were measured. The maximum achieved end-to-end dc-to-ac system efficiency was 54.18% with a probable error of + or - 0.94%. The dc-to-RF conversion efficiency was measured to be 68.87% + or - 1.0% and the RF-to-dc conversion efficiency was 78.67 + or - 1.1%. Under these conditions a dc power of 495.62 + or - 3.57 W was received with a free space transmitter antenna receiver antenna separation of 170.2 cm (67 in).

Variable length instruction decoding apparatus having cross coupled first and second microengines

Abstract: A pipeline computer architecture having two interconnected microengines operating simultaneously in an instruction preparation unit of a pipeline computer system. Each microengine operates on the same portion or different portions of an instruction concurrently within the same clock cycle. To assure coordination, one microengine is declared the executive or attribute generator and the other the main microengine. The main microengine generates routines to control the instruction preparation unit hardware. The executive microengine prepares the next tank in parallel and supplies arguments to the main microengine as the main microengine generates its current routine. At the completion of a routine performed by the main microengine, it signals the executive microengine to obtain the next task and associated parameters.