Waveguide Packaging Research Articles

Optoelectronic and microwave characteristics of silver coated indium bumps for low temperature flip-chip applications

The effect of silver coating on pure indium bumps for low temperature and high speed flip-chip applications is presented with respect to optoelectronic and microwave characteristics. The current-voltage and light power-current characteristics of flip-chip bonded vertical-cavity surface-emitting laser (VCSEL) arrays are improved by coating a thin silver layer of 0.2 µm. The flip-chip assembled coplanar waveguide packages using silver coated bumps show the insertion loss is about 3.3 dB/cm at 20 GHz and the return loss is under 13 dB.

Improvement of Adhesion and Microwave Transmission Characteristics of Indium Bump by Silver Coating for Low Temperature Flip-Chip Applications

ABSTRACTWe have conducted low-temperature flip-chip bonding for both optical interconnect and microwave applications. Flip-chip bonding of vertical-cavity surface-emitting laser (VCSEL) arrays was performed on a fused silica substrate that provides propagation paths of laser beams and also supports a polymeric waveguide. To avoid thermal damage of the polymeric waveguide during the flip-chip bonding, indium bumps were used and the bonding condition of the flip-chip was determined as a heating temperature of 150 °C and a pressure of 500 gf. Experimentally, a thin silver (Ag) layer coated on the indium bump was very effective to enhance the adhesion strength between the indium bump and the VCSEL chip pads. In addition, the microwave characteristic of coplanar waveguide (CPW) package was slightly improved by the Ag coating.

Microwave Integrated Circuits--An Historical Perspective

Before attempting an historical view of microwave integrated circuits, it was necessary to consider just what a microwave integrated circuit is. If someone can come up with a clear, noncontroversial, universally accepted definition, he's a better man than I am. In the broadest sense, a microwave integrated circuit is any combination of circuit functions which are packaged together without a user accessible interface. This definition, however, opens the door to great kluges of waveguide bends and components which have been brazed or welded together, and that is clearly not the intent of this review. I have, therefore, limited the scope to planar integrated circuits which make use of process control manufacturing techniques for a significant portion of the integrated circuit, This would include such transmission-line techniques as stripline, rnicrostrip, slotline, finline, co-planar waveguide, and to a slightly lesser extent, lumped element circuits, image guide dielectric waveguides, and planar waveguide packages which are becoming a viable technique for integrated circuits at millimeter-wave frequencies.

A 5-db noise figure backward-wave amplifier at X band

The Backward-Wave Amplifier is a very useful pre-amplifier for microwave receivers. Its selectivity, crystal protection and low noise figure offer advantages in various communication and radar systems. An X-band BWA has been developed which has produced minimum noise figures of db. These tubes operate with the following characteristics over the 8.5 - 9.5 kMc frequency range: gain 20 db, noise figure less than 5.5 db with minimum of 4.5 db, bandwidth 12 mc \pm 2 mc, 6.5 mc/volt tuning rate. The important parameters which determine these characteristics will be described. The tube is encapsulated in a novel waveguide package that uses semicircular waveguide. This package provides waveguide input and output terminations in a minimum cross-sectional area.