Leadership Team

William F. Weissman

William F. Weissman was named Rubicon's President, Chief Executive Officer and a member of the Board of Directors in December 2014. He served as our Chief Financial Officer from July 2007 until December 2014. From 1995 to 2007, Mr. Weissman served in various capacities at Kanbay International, Inc., an information technology services firm, including chief financial officer and executive vice president. Mr. Weissman has also held various finance positions at Lockheed Electronics and Airco BOC. Mr. Weissman is a certified public accountant and holds a BA in business administration from Seton Hall University.

Mardel A. Graffy

Mardel A. Graffy has served as our Chief Financial Officer, Treasurer and Secretary since December 2014. Ms. Graffy joined Rubicon in January 2005 as Director of Finance and was named Controller in July 2007, Vice President of Finance in July 2008 and Vice-President of Financial Operations in September 2014. From 1987 to 2004 she served in various capacities at FMC/FMC Technologies, Inc., a world leader among producers of chemicals and machinery for industry and agriculture. From 1982 to 1987 she was with KPMG, a public accounting firm. Ms. Graffy is a certified public accountant and holds a BS in accounting and business administration from Illinois State University.

Hany Tamim

Hany Tamim, Chief Operating Officer, joined Rubicon in October 2015. Mr. Tamim has extensive experience in managing crystal growth and wafer manufacturing operations in both Malaysia and the United States, including 24 years with SunEdison (formerly MEMC), where his experience included leadership roles in global cost management, plant management and process engineering. He has Bachelor and Master of Science degrees in engineering from the University of North Carolina.

Christine Richardson

Christine Richardson, our Chief Technology Officer, joined Rubicon in April 2015. Dr. Richardson has over 15 years of senior technology leadership experience and was formerly Vice President, Crystal Growth Systems Development and Engineering at GT Advanced Technologies. Her earlier experience includes leading photovoltaic technology development for GTAT, advanced process development for Evergreen Solar; and process development engineering for Advanced Micro Devices. Dr. Richardson has a PH.D. in applied physics from the California Institute of Technology, M.S. degrees in applied physics and materials science and engineering from Harvard University and Stanford University respectively, and a B.S. in materials science and engineering from Johns Hopkins University.

Hap Hewes

Hap Hewes, Senior Vice President, Optical, rejoined Rubicon in January 2015, having previously served as Rubicon’s Senior Vice President, Sales and Marketing, from 2006 through 2009 and Rubicon’s Senior Vice President, Supply Chain and Business Development, from 2004 to 2005. In between, Mr. Hewes was Senior Vice President, Operations, Sales, Marketing, and Field Service, for ARC Energy, a capital equipment provider for the LED industry and other high-tech markets. Concurrently, he served as interim CEO for a related company, ABS Materials, Inc. Mr. Hewes also worked for Saint-Gobain Crystals and for Saphikon, Inc., a crystal manufacturer that was acquired by Saint-Gobain. Mr. Hewes has an MBA degree from the University of Michigan and a BS in biology from Cornell University.

Jason Yu

Jason Yu, Vice President, Sales, joined Rubicon in 2008. He previously worked in technical and sales capacities with Photronics (formerly PKL), Mattson Technology, CFM Technologies, and Monsanto. Dr. Yu has a Ph.D. in chemical engineering from Northwestern University and a BCHE in chemical engineering from The Cooper Union for the Advancement of Science and Art.