Today's telecommunications/datacom industry is coping with its own technical challenges in processing capabilities through the continuous juggle of requirements between greater electrical performance and reduced package sizes. Automatic eutectic attachment techniques, which are desirable for high-performance and high-capacity die attach applications, are constantly in high demand.
The eutectic die attach technique is nothing new. This die-bonding technique has been widely explored and employed, historically on manual die-bonding equipment. What is new, however, is its elevated place in an industry environment where current and future needs—high-volume and high-placement accuracy (±5 microns)—clearly call for flexible automated equipment. In particular, demands for high-volume and high-placement accuracy require automation that is swift, precise and repeatable.
Understanding the Eutectic Process
When different metals are combined into alloys, a range of melting temperatures is created with varying proportions of each metal used, such as Au/Si @ 363°C Au/Sn @ 280°C.
In many cases during soldering, a cover gas is employed, which usually contains a passive component (such as 90 percent nitrogen) to prevent metal oxides from forming, and an active component (such as 10 percent hydrogen) to break away existing metal oxides. The solder, usually precipitated to the die foundation (backside metallization) or to the substrate surface, can also be supplied as a preform—solder pieces cut to a certain percentage of the die size. While preforms are a cheap solution to apply solder, their use does require an additional pick-and-place process step.
Eutectic die attach offers a number of advantages over similar techniques, of which good thermal solder conductivity and immediate fixing after bonding are most significant.
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Download "Automated Eutectic Die Attach: Ideal for Telecom and Datacom".
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Zeger Bok
Senior Applications Engineer
Palomar Technologies