Due to the rapid growth in the use of Internet and mobile communications, the high speed transmission capacity requirements have been increasing at a high rate. As a result of this, the semiconductor and packaging technologies have seen significant advances. Especially, wireless communication systems in the microwave/millimeter wave bands, such as LMDS (Local Multipoint Distribution System), Point to Point radio, and satellite communications are expected to see significant growth in a consumer market.High Frequency Integrated circuits to be used in broadband transmission would be implemented in materials such as GaAs, SiGe, and InP. Some effort is seen to develop passivation films for these devices so that they can be used without additional packaging, but so far these attempts have not met with much success. The requirements for ceramic packaging have remained very strong and stable. As the microwave/millimeter wave applications are gradually transferring to the consumer market, the packaging must meet the demands for high reliability, miniaturization, lower cost, and low electrical loss. Although several surface mount package types for high frequency have been proposed to meet those requirements, the return loss starts dropping drastically around 30GHz level. Then, there are no clear reports on the work done to reduce these losses.This paper shows and explains the key points of the simulation and design technologies for high frequency SMT package. Then, we introduce practical examples of packages designed for high frequency by using simulation technology in order to improve the transmission properties of the package. We have manufactured prototype samples of such packages and confirmed the results of simulation by actual measurements. The measurement results show S11<-15dB and S21<-1dB per port up to 50 GHz (including the board interface). Therefore we introduce a surface mount BGA package suitable for up to 50 GHz. As for package material, we used low loss LTCC(Low Temperature Cofired Ceramic [GL560]), (Er=6.0, tangent delta= 0.0023 at 10 GHz) in order to lower the capacitance at the ball portion.

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The significantly increasing transmission capacity in the subscriber system are accelerating demands for higher data transmission speed, low cost, and system miniaturization in the millennium approaches. The key solution for the demands, smaller, lower cost, and high performance package, is surface mount technology. OptoBGATM package has been developed to meet this challenge, a surface mountable type optical package that is designed for high frequency transmission speeds.OptoBGATM package has a BGA structure to bring forth effectively size and cost reduction for the packaging.OptoBGATM consists of ceramic material, a robust material, which has many advantages such as design flexibility with fine design rule, ease of process technology, high performance, and high reliability. The design of OptoBGATM was made possible by improvement in the physical structure.The results of this research produced an OptoBGATM with a return loss of about -20dB at 1 0GHz (the measurement is taken from IC pattern mounted inside the package to I/O terminal). Furthermore, reliability test evaluations have been conducted to demonstrate that the OptoBGATM can withstand harsh environments.

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