The board of Japanese conglomerate Toshiba has approved a plan to sell its lucrative microchip business to a group of American and Japanese buyers, bringing the company closer to a deal it may need to survive, the New York Times reported today. Details of the sale must still be finalized, Toshiba said yesterday, leaving open the possibility of another turn in a drawn-out bidding process marked by reversals, acrimony and confusion. The Japanese company said the microchip unit would be sold for 2 trillion yen, or roughly $18 billion. The structure of the deal is complicated, and Toshiba said it would retain partial control of the business. It was not clear yesterday how much would end up being owned by outside investors. Those investors primarily include Bain Capital, an American buyout firm, and two organizations controlled by the Japanese government, the Innovation Network Corporation of Japan and the Development Bank of Japan.