Hermetic package for optical MEMS

This article describes the design and fabrication of a hermetic LTCC package for an optical MEMS chip designed for space applications. The package must ensure electrical and optical connections, mechanical positioning, atmosphere control, and finally low thermally induced stress on the MEMS during final packaging operation. The package consists of a 10-layer LTCC case with a recessed cavity for the MEMS chip, and glass lid (with antireflection coating and thin-film metallisation for soldering) for optical I/O. The chip is mechanically attached to the bottom of the cavity with a silicone adhesive, and electrically connected through gold wire bonds. The gold wire bonding pads are routed through the LTCC module to a MegArray BGA connector. Hermetic closure of the cavity is carried out by soldering the glass lid onto the case in a controlled atmosphere. The two main difficulties involved in such a package are the high electrical connection density (400 connections) and low-temperature hermetic sealing. LTCC design rules for small-pitch lines, thick- and thin-film materials selection, screen-printing, lamination techniques and soldering methods are described in this article.

Published in:
Journal of Microelectronics and Electronic Packaging, 6, 1, 32-37
Version of conference paper (LPM-CONF-2008-018), invited for publication in JMEP

Note: The status of this file is: EPFL only

 Record created 2009-08-19, last modified 2018-09-13

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