A cost
effective method is provided for
assembly of
hybrid optoelectronic circuits requiring flip-
chip bonding of multiple active optoelectronic devices onto common substrate or optical bench platform with
fine pitch and high accuracy "after-bonding" alignment to the alignment features on substrate and / or to other elements of the
hybrid circuit. A Flip-
Chip Bonder equipped with high precision Bonding Arm and optical and
mechanical system, heated substrate chuck and heated pick-up tool may be used both for alignment and
thermal bonding of
active component dies to corresponding bonding pads on the common substrate using gold-
tin (Au-Sn) solder disposed between
die bonding pad and the corresponding substrate bonding pad. During bonding of the first die,
tin (Sn) diffuses from a eutectic composition of gold-
tin (Au-Sn) solder to (gold (Au) on) the die-bonding pad and / or (gold (Au) on) the substrate bonding-pad resulting in transformation of the Au-Sn eutectic composition to a zeta-
phase composition having much higher
melting temperature as compared to that of a eutectic composition. As bonding of one or more subsequent dies is performed at temperatures equal to or slightly higher than the
melting temperature of a eutectic composition and significantly lower than the
melting temperature of a zeta-
phase composition, the gold-tin (Au-Sn) solder at the bond of previously attached die does not melt and, consequently, the alignment is not compromised.