Three dimensional packaging and interconnecting techniques for microwave modules
Three dimensional (3D) packaging and interconnecting techniques can greatly reduce the weight and volume of conventional planar microwave modules. The objective of this study was to employ a novel 3D structure with simple manufacturing process to develop 3D microwave modules. Many advanced 3D packaging and interconnecting methods, such as LTCC microwave multichip modules, vertical interconnects, and 3D electromagnetic field analyzing and optimizing, were applied to increase the package density and improve the electric performance. Test method and test results of 3D microwave modules were introduced. These techniques are very useful to many types of modern active phased array radar systems and communication systems.
High density packaging of X-band active array modules
A new high-density package design has been used to reduce the cost, weight, and size of X-band active array radars. The package used multilayer aluminum nitride (AlN) substrates, flipped monolithic microwave integrated circuit (MMIC) chips, coplanar waveguide transmission lines, and solderless fuzz button interconnects. This paper discusses the design tradeoffs, the package construction and assembly, and test results.
The etiology and surgical management of tracheal collapse in calves.
The mean ages of 10 calves with tracheal collapse were 2.7 weeks at onset of clinical signs and 9.4 weeks at presentation for treatment. Inspiratory and expiratory dyspnea and stunted growth were the most common clinical signs. There were abnormalities of the cranial ribs consistent with healing fractures with redundant callus in eight lateral thoracic radiographs. Tracheal collapse in calves may result from cranial thoracic trauma during or soon after birth. Short polypropylene ring prostheses made from 60 ml syringe barrels were placed on the tracheas of four calves with cervical tracheal collapse. There were cranial rib masses in all calves and resection of the right first and second ribs was necessary in one calf to allow placement of prostheses. Dyspnea was relieved in all calves. One calf died of unrelated causes in year 3, and one calf had recurrence of clinical signs at month 5 and was euthanatized. In both calves, tracheal stenosis resulted from continued growth and infolding of the trachea within the constraints of the prostheses. One calf was alive at month 11, and one calf died of acute bronchopneumonia on day 2. Removal of tracheal prostheses in calves is recommended after 2 to 3 months if clinical signs recur.