SAN DIEGO -- A DDi Corp.investor has filed a lawsuit against the printed circuit board fabricator's directors in effort to block its proposed takeover by Viasystems Group.

According to the complaint, the plaintiff alleges that the defendants breached their fiduciary duties owed to stockholders arising out of the attempt to sell DDi via an unfair process at an unfair price.

On April 4, Viasystems announced it would acquire DDi for $13 per share in cash, or $282 million ($268 million net of DDi’s cash plus assumed debt). The offer represented a 20% premium to the volume weighted average price of DDi’s common stock over the previous three months, and is about 8.3 times the firm's 2011 EBITDA.

The suit alleges that the offer undervalues the company, and does not account for the "significant synergies created by the merger." At $13 a share, the offer is 6% over DDi's closing stock price of $12.26 on April 3. The stock started trading close to (but never topping) $13 a share as of April 4, suggesting word had leaked about a possible sale. (DDI shares have a 52-week low of $6.66.) The offer represents a roughly 32% premium over the stock's low in late January.

According to the suit, DDi's recent strong performance -- the company has turned in three straight profitable years and annual revenue increased from $190.8 million in 2008 to $263.4 million in 2011 -- and its position for growth, the offer is inadequate. Furthermore, the plaintiff alleges, the process is unfair to stockholders, as DDi’s board of directors and certain management executives have already agreed to vote a number of common shares representing approximately 23% of the outstanding shares of DDi in favor of the merger.

Investors who purchased shares of DDi prior to April 4, 2012, and currently hold any of those shares can opt to be part of the suit.

A similar suit was filed in 2008 following Viasystems acquisition of Merix. The suit was settled in November 2011 for $1.5 million.