SI Technologies was acquired by Vishay Intertechnology on April 28, 2005. SI Technologies is now part of Vishay Intertechnology, one of the worlds largest manufacturers of discrete semiconductors and passive electronic ......SI Technologies was acquired by Vishay Intertechnology on April 28, 2005. SI Technologies is now part of Vishay Intertechnology, one of the worlds largest manufacturers of discrete semiconductors and passive electronic components. Vishay Intertechnology includes Vishay Measurements Group, which develops, manufactures, and markets a broad range of sensors and systems for a wide variety of test and measurement applications.