How does Indigo compare to the new solders?
Soldering is a viable alternative for materials with relatively close CTEs. Indium-based solders have been used for attaching integrated heat spreader lids to silicon dies. This is possible because such solders are highly compliant and mitigate the mechanical stress that would otherwise cause damage to the die or the bond during thermal cycling. Obtaining this compliance, however, requires a BLT of 7-10mil or higher; the quantity of indium required for such a thickness results in significant cost.
