Jürgen Breier, SCHOTT GLAS, Mainz
In diodes, special glass has the function of hermetic encapsulation. One of the leading manufacturers of these glass electrodes is Vishay Semiconductor of Austria.
Since 1965, the specialist manufacturer of electronic components (diodes, rectifiers and transistors) has been headquartered in Voecklabruck, 70 km east of Salzburg (Austria). It was only in 1998, that the company, then called Temic-Telefunken, was acquired by Vishay Intertechnology, Inc. of the United States. This group of companies, with sales of US$ 1.8 billion last year, employs 20,000 people in more than 60 factories located in 14 countries.
“The Voecklabruck plant functions as a competence center, especially for glass diodes,” said Division Head Gerhard Speidel. The development, construction and the testing of new production lines takes place at this location. The responsibility for uniform worldwide quality standards, global production planning and distribution, as well as certain areas of marketing, development and application lie in Voecklabruck. The actual transfer work is done mostly in the high-volume glass diode plants located in Gyoengyoes (Hungary) and Shanghai (China). Vishay Semiconductor employs about 2,000 workers throughout the world, a fourth of them in Voecklabruck.
The right timing for expansion
Vishay Semiconductor has doubled its manufacturing capacity to 14 billion diodes per year.
The world’s smallest diode
The blister belts with the inserted diodes are wound into reels.
Although management has automated as much of the manufacturing process as possible, there are still some manual tasks to be done at Voecklabruck. For instance, the cut-to-size precision tube sections supplied by SCHOTT Rohrglas of Mitterteich (Germany) are separated into individual slots of a graphite tray. The tube sections are fitted with two metallic feed lines and a chip. The tray is then placed on a conveyor belt, which moves slowly through a melting furnace. After one hour the glass and the metal wire are melted together. The diode is then chemically cleaned and the wires are hot tinned and dried with hot air, before polarization and the attaching of the cathode ring. Once finished, the diode is inserted with lightning speed into a narrow blister belt. An astounding 80,000 pieces per hour and machine are packed into the belts and then wound up in reels, which the client later unwinds during the assembly process. The diode is then inserted into the electronic part using the fully automated pick-and-place principle.
“The precision glass sections are a decisive factor for guaranteeing the best possible manufacturing process as well as the quality of the diodes. An inexact measurement, the wrong length or coarse breaks and the whole production process is slowed or can come to a total standstill in extreme cases”, explains Purchasing Director Helmut Fink. 95 percent of the glass parts processed in the Austrian, Hungarian and Chinese plants are supplied by SCHOTT Rohrglas. SCHOTT has been a reliable and high-quality supplier and development partner for three decades. For this reason, we have largely done away with inspections. We accept the supplier’s certification, testing records and random tests performed within the framework of their own QS 9000 obligations.”
Rectifier diodes meet high standards
Rectifier diodes for high voltage and high temperature applications.
Vishay Semiconductor wants to remain successful. “We try our best as suppliers not to limit the growth dynamism of our clientele”, said Speidel. The planning certainly expresses his optimism: By 2001, the annual turnover is forecast to increase by 15 percent, to about 200 million euros, with 60 percent of total sales coming from glass diodes.