Congress gave final approval yesterday and sent to the president a bill making it a crime to copy computer chip designs without permission.

"This is is extremely important for us," said R. Michael Gadbaw, an attorney with the Semiconductor Industry Association, which had lobbied hard for the bill, approved unanimously by both the House and the Senate. "It's going to finally protect the industry from piracy of its chip designs."

The new bill, written in part by Rep. Robert Kastenmeier (D-Wis.), confers an entirely new form of protection to semiconductors called sui generis -- the Latin phrase meaning "a thing unto itself," that is neither patent nor copyright.

Silicon semiconductor chips have brought the power of the computer into a space the size and thickness of a thumbnail. Computer chips can be found in everything from personal computers to microwave ovens to telephones to automobiles.

However, the design of the chips, which gave them their "intelligence," did not enjoy any form of copyright or patent protection until yesterday's passage of the Semiconductor Chip Protection Act of 1984.

Several overseas competitors have "plagiarized" the chip designs of American companies because it was cheaper to copy the chips than spend the millions of dollars necessary to design and prototype them.

However, under existing laws, there was no specific recourse that American chip designers could take to stop copying. Many legal experts challenged the idea that chip designs could be protected by copyright, patent or trade secrecy law, the traditional ways intellectual property has been protected.

Convicted violators of the new law, which covers chips designed after Jan. 1 1983, could be fined up to $250,000. More importantly, says SIA's Gadbaw, "We can stop the chips from being sold; we can stop them from coming in at the border."

The move to protect semiconductor chips underscores the belief held by many economists and high-technology industrialists that new laws are required to protect new kinds of intellectual property created by new technologies.