3D Packaging 3D Packaging - August 2012 : Page 25

ISSUE N°24 AUGUST 2012 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Final test + Scrap (Omnivision) 11% CIS/WLO Assembly & Housing Cost 9% IR filter Lens #1 Glass wafer #2 Lens #2 AP layer WL-Optics cost + Royalties 30% FR-4 Spacer Housing Wafer-level Optics Glass Wafer #2 (carrier wafer) Imaging Area with micro-lenses TSV Wafer-level Packaging CIS WLP Cost + Royalties 49% CMOS Image Sensor Cavity Bumps Nemotek WLC structure & cost breakdown. (Courtesy of System Plus Consulting) Polydimethylsiloxane -PDMS silicone) molded into a master is used to imprint the polymer lenses. Each master can be used to make a large number of PDMS tools, and each PDMS tool can be used to imprint a large number of lenses. The lenses are covered with a thin anti-re fl ective coating (ARC). The two sides of the glass wafer also hold an IR fi lter (consisting of layers of Titanium oxide sandwiched with layers of Silicon oxide) and an aperture made of Chromium layers. FR-4 Lens #1 Glass wafer with lenses & IR fi lters FR-4 Cost structure The main bene fi t of working with Nemotek is that it is a “one-stop shop” which provides a complete solution, from optics to packaging, thus eliminating overhead related to multiple subcontractors. On the downside, Nemotek uses optics and packaging technologies licensed by Tessera, and has to pay royalties for these. To wrap things up, the complete Wafer-Level Camera assembly cost (without the CMOS Image Sensor) is close to 30 cents, which is very competitive compared to other previously-analyzed technologies from ST, Toshiba and Omnivision. The Wafer-Level Packaging of the CIS remains the main cost driver, with ~50%. www.systemplus.fr Lens #2 FR-4 FR-4 WLP CIS Wafer-level optics cross-section. (Courtesy of System Plus Consulting) The lenses wafer is separated from the image sensor by a FR-4 spacer wafer (Glass-Fiber-Reinforced Polymeric Resin) which is etched using a standard, PCB-like mechanical drilling process. Romain Fraux, Electronics Cost Engineer, System Plus Consulting Romain Fraux is Project Manager for Reverse Costing analyses at System Plus Consulting. Since 2006, Romain is in charge of costing analyses of MEMS devices, Integrated Circuit and electronics boards. He has signi fi cant experience in the modeling of the manufacturing costs of electronics components. Romain has a BEng from Heriot-Watt University of Edinburgh, Scotland and a master’s degree in Microelectronics from the University of Nantes, France. 3D P ackaging 27

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