Wednesday, July 27, 2011

Manufacturing cost of monolithic and hybrid microsystems

A complete cost analysis of monolithic versus hybrid microsystem had been made together with over 50 (received answers from 90 companies to which the question was sent) manufacturing MEMS companies from Europe, USA and Asia. The problem which was discussed is as follow:  which of monolithic or hybrid MEMS integration solutions are more expensive.
Of course, the answers were different for each of company and some companies could not give us a definite answer. Figure 5 shows a graphically repartition of the answers which were gave by MEMS companies. Most of them estimated that the monolithic integration is a cheaper  In general, monolithic systems are only considered were the production volumes are expected to be very high (several 10's or 100's of millions of parts per annum).
Main conclusions of monolithic versus hybrid microsystem are: the hybrid MEMS solution represents a bigger unit cost that an alternative, monolithic solution; the assembly and packaging cost is higher compared to the monolithic approach; for monolithic approach the MEMS above CMOS (Post-CMOS) is more cost competitive than MEMS below CMOS (Pre-CMOS); the package of MEMS is very expensive - packaging currently represents more than 80 percent of the cost of some systems and is often the leading cause of system failure. A design of a new thermally actuated microscanner is proposed. The device with respect to the cantilever beams assures the high precision of scanning action. The distance of the centre of the mirror from the light source is the same during the whole scanning process. It allows projecting an image with fewer distortions. The rest position of the mirror and resonant Scanning micromirrors are used in devices for imaging, bar-code reading, laser surgery, laser machining, etc.
Modern MEMS and MOEMS technologies classified microscanners with respect to its actuation principle. The most common are: electrostatic, piezoelectric, electromagnetic and thermally properties. Thermal actuators, formed as thermo-bimorph beams, provide large scan angle, nearly linear deflection versus power relationship and moderate power consumption. Moreover, fabrication of such microscanners is based on very cheap technology. Thermal actuators do not operate with as high frequency as electrostatic or piezoelectric ones, but high enough for some optical applications. Proposed microscanner is composed of a round micromirror and four thermal-bimorph beams, Fig. 1 [2]. The beams play a role of actuators deflecting (moving with a high speed ? for raster scanning) is fixed directly to the mirror, and to a rigid movable frame. Second pair of the bimorph beams (moving with a low speed ? for frame scanning), are situated perpendicularly actuators are composed of two layers with different coefficients of thermal expansions (CTE) and a thin insulator layer between them, Fig. 2c.

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