Hermetic joining of micro-devices using a glass frit intermediate layer and a scanning laser beam

Abstract

In this paper we investigate and compare a laser-driven joining process with two different illumination conditions: (i) high speed scanning of a focused beam and (ii) reasonably uniform ldquoflood illuminationrdquo of the whole sample. It is shown that the scanning beam not only avoids illuminating the central part of the device, but also provides more uniform heating of the area to be bonded than laser ldquoflood illuminationrdquo. We demonstrate bonding of three different packages: (i) LCC (Leadless chip carrier) packages, (ii) AlN and (iii) LTCC (Low temperature co-fired ceramic) substrates to ldquotop-hatrdquo packages, using a scanned beam from a fibre-delivered high power laser diode array to cure an intermediate layer of glass frit. Standard leak testing demonstrates that all those samples have excellent hermetic sealing with leak rates at the level of 10-9 atmldrcc/s.