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SUMMARY The effects of thermal-dissipation structure on the thermal performance of nanoscale InGaP/GaAs collector-up heterojunction bipolar transistors were investigated by using the advanced hybrid optimization technique, a combination of the three-dimensional finite-element method for temperature-distribution analysis and the technology computer-aided design tool for power-performance evaluation. Through adequately locating the thermal-dissipation structure at the rear side of the transistor and via effective thickness-thinning procedures, which reduce foundry cost, the thermal coupling between collector fingers has been greatly ameliorated and a power-added efficiency of 45% is achieved. Copyright © 2013 John Wiley & Sons, Ltd.

SUMMARY An effective device structure for thermal management of multifinger InGaP/GaAs collector-up heterojunction bipolar transistors (HBTs), compelling active components in high-efficiency handset power amplifiers, is presented for the first time. From the unique 3-D thickness-adjusting numerical analysis, based on a finite element model, the miniaturized device can lead to a greater than 40% reduction in the thickness of plated gold layer. Above all, this is quite different from previous attempts, in which the thermal resistance was reduced by increasing the thickness of plated gold layer. Compared with literature works, the thermally stable design with an innovative heat-spread configuration shows a 50% reduction in thermal resistance and demonstrates favorable power performance. Copyright © 2013 John Wiley & Sons, Ltd.

In this paper, we have successfully developed an intellectual parameter-extraction methodology on the basis of a genetic algorithm (GA), involving the efficient search-space separation and local-minima-convergence prevention schemes. Via an evolutionary simulation tool complemented with appropriate analytic equations, the enhanced approach has been applied to determine the significant figures-of-merit (FoMs), including internal quantum efficiency (ηi) as well as transparency current density (Jtr) of semiconductor lasers, minimum noise figure (NFmin) as well as associated available gain (GA,assoc) of low-noise amplifiers (LNAs), and DC as well as AC characteristics of heterojunction bipolar transistors (HBTs). For the first time, demonstrated FoM-extraction results, which coincide well with the actually measured data, for state-of-the-art InGaAs quantum-well lasers, advanced SiGe LNAs, and abrupt ZnSe/Ge/GaAs HBTs are simultaneously presented to validate this multi-parameter analysis and robust optimization. Copyright © 2011 John Wiley & Sons, Ltd.

The specific volume of polymer blends with different degree of compatibility has been measured at high pressure, up to 2000 kg/cm2, in the molten state by a dilatometer. The specific volume and thermal expansion coefficient of the molten homopolymers at zero pressure were satisfactorily fitted to a simplified Simha–Somcynsky equation. The specific volume of styrene–butadiene (SBR) random copolymer, which is considered to be a compatible system, at a constant styrene composition can be calculated by an semiempirical equation based on the Tait equation. The temperature dependence of excess specific volume of SBR with different styrene content at zero pressure was estimated by a combining rule in terms of self-and cross interactions. The concentration-dependent equation is derived to estimate the specific volume of SBR with various styrene contents. Both the thermal and dynamic mechanical analysis of the blend from the two polystyrene (PS) and polybutadiene (BR) homopolymers show a low degree of compatibility. The weight fractions of each domain consisting of PS blending with BR and those of the components in each domain can be calculated from the mass balance on the two domains and the rearranged Couchman equation. The specific volume of PS–BR composed of two phases obeys the principle of additivity from the weight fractions of the specific volume of the corresponding phases. © 1994 John Wiley & Sons, Inc.

The heat capacity and phase relation of polymer blends consisting of two homopolymers or a homopolymer with a block copolymer have been investigated by differential scanning calorimetry (DSC). Polystyrene (PS) and polybutadiene (BR) are the two homopolymers, while the styrene–butadiene–styrene (SBS) copolymer is employed as the block copolymer in this study. The heat capacity and specific volume of the PS and BR homopolymers increase with increasing temperature at a constant pressure. The heat capacity of styrenebutadiene (SBR) random copolymer, which is considered a miscible system, can be calculated by an additive rule from the addition of the styrene and butadiene segment number fractions in the random copolymer multiplied by the corresponding heat capacity of PS and BR homopolymers. However, the heat capacity of the immiscible system of the SBS triblock copolymer can be estimated by the addition of the two segment number fractions multiplied by the reciprocal of the corresponding heat capacity of the PS and BR homopolymers. The thermal and dynamic mechanical analysis data of the polyblend from the two PS and BR homopolymers both show a low degree of miscibility. A saturated solubility of the homopolymer dissolved in the SBS block copolymer is proposed and the purification of the styrene and butadiene phases in the SBS copolymer is observed as it blends with either PS or BR homopolymer. The heat capacity of polymer blends composed of two phases obey the principle of additivity from the weight fractions of the heat capacity of the corresponding individual phase. © 1993 John Wiley & Sons, Inc.

The specific volume of thermoplastic polymers and composites with glass fiber have been measured at high pressure, up to 2000 kg/cm2, in the molten state by a dilatometer. The specific volume and thermal expansion coefficient of the melts increase with increasing temperature at a constant pressure at a constant temperature. The data of specific volume of molten polymers were satisfactorily fitted to an empirical equation of state based on the Tait equation. Furthermore, it is found that the data of specific volume of molten composites were suitably fitted by an additive rule of Tait equation from the volume fractions of specific volume of polymers and the glass fiber in composites. The thermal expansion coefficients of molten polymers and composites are approach to the derivative values of the Tait equation, and the additive Tait equation, respectively.

The thermal conductivities of molten polypropylene and its glass fiber composites were measured by the compensating hot wire method. The testing apparatus empolyed was designed and tested in our laboratory. The measurements were carried out with temperatures ranging from 170 to 230°C and pressures from 1 to 2000 kg/cm2. The results show that the thermal conductivity increases with increasing pressure and glass fiber content, but is almost independent of temperature. The thermal conductivity data were fitted satisfactorily with a proposed empirical equation for polypropylene and Lewies-Nielsen equation for the composites, respectively.