Sony STR-DA9000ES - Manual (Page 15)

ES Receivers v1.0 Page 15
Building on this experience, the redesigned MOS FETs for the STR-
DA7100 use "sheet metal molecular bonding." In this design, the semiconductor
and the three Source electrodes are connected by an aluminum sheet. (The
other electrode is the Gate. The Drain on the bottom of the FET is die attached.)
While the double wire bonding of the DA9000ES achieved a low resistance of 5
milliohms, the sheet metal bonding of the DA7100ES reduces this to just 1
milliohm or less. Also current capacity is increased and internal resistance of the
MOS FET is cut in half. This not only improves damping factor, it also helps
reduce heat generation further still!
Illustration of the bare transistor of the STR-DA7100ES MOS FET,
showing connections for Source (S), Gate (G) and Drain (D). Sheet
metal molecular bonding provides the Source connection at 80%
reduced resistance, compared to the MOS FETs of the DA9000ES.
Internal layout of the DA7100ES. (1) Power supply. (2) S-Master Pro.
(3) Preamp and video section. (4) Input signal processing. Note how
small the power amplifier is.