Frank Seigneur

A case study of surface tension gripping: the watch bearing

This paper reports the modeling and experimental work done for the design of a microgripper using surface tension forces for the handling of submillimetric balls of a watch bearing. Its originality lies in the adaptation of existing capillary forces models to this microassembly case study and in the exhaustive characterization work required as a first step towards an automated assembly. Picking and placing operations have been experimentally studied, and solutions are proposed to tackle the typical related problems. The component feeding should be studied in detail.

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. Keywords: LTCC, Hermetic Packaging, MOEMS, Interconnections, Solder Sealing.

Laser Sealed Packaging for Microsystems

Packaging is the last process of microsystem manufacturing. There are mainly two kinds of packages: plastic or metallic. The two main components of the package (base and cover) may either be glued or soldered. Each of these techniques has its advantages and drawbacks, and the choice should be driven by the functionality of the microsystem.

Design of a Capillary Gripper for a Submillimetric Application

This paper describes the study of a gripper using the surface tension effects to pick and place the 0.5mm or 0.3mm diameter balls of a millimetric watch bearing. Two liquid supply strategies have been tested (pressure drive and tip dip). The effects of the coating (through the measurement of the contact angles), the presence of an internal channel and the size of the gripper have been studied. Analytical and numerical force models have been developped and validated thanks to a test bed allowing the measurement of the developped force (typically of the order of 100 µN) with a resolution of 1 µN. A complete pick and place cycle has been performed using the 0.5mm diameter gripper. Such a test has still to be done in the future with the 0.3mm diameter gripper.