The Zhejiang SiFang electron limited company, founded in 1970, In 1997 through the ISO9001: 1994 quality system authentication, in 2003 passed the ISO9001: 2000 quality system authentication. The SiFang leading product has the sign electric valve, the thyristor, the fast thyristor, the electric power module, the solid state relay and each kind of electric power electronic building brick and so on 80 products. The product widely applies in the machinery, the metallurgy, the automobile, the electric power, galvanizes domains and so on power source, electrochemistry, electric power dragging, national defense war industry.