SEATTLE (AP) ¿ Cell phone design and manufacturing company China TechFaith Wireless Communication Technology Ltd. said Monday its second-quarter profit rose 17 percent, helped by a one-time gain. But sales slipped 12 percent, and investors sent shares down 6 cents, or 2 percent, to $2.88 in after-hours trading. Earlier, the stock gained 21 cents, or 7.7 percent, to close at $2.94. The Beijing-based company's earnings for the three months ended June 30 increased to $4.5 million, or 10 cents per U.S.-traded share, from $3.9 million, or 9 cents per share in the same period last year. Results included a $2.1 million gain from a change in fair value of certain debt. Sales slipped 12 percent to $49.8 million from $56.6 million in the year-ago quarter. TechFaith's product sales group's revenue dropped 6 percent to $48 million. Its handset design business' revenue sank 71 percent to $1.6 million. The company said its deputy chief executive, Wilson Cai, is resigning because of personal health concerns. Cai replaced Bob Huo a year ago. His spot on the board will be filled by Dong Deyou, another TechFaith executive.