* First-half pretax profit rises 57 pct
* Revenue from performance materials rises
* Co says new product launches to drive second-half results
* Shares rise more than 7 pct (Adds details, analyst comment, share price)
By Abhiram Nandakumar and Noor Zainab Hussain
July 31 (Reuters) - Laird Plc posted a 57 percent rise in first-half pretax profit, driven by strong demand for products that improve mobile signal clarity and prevent smartphones from overheating.
The company's shares rose more than 7 percent to rank among the top percentage gainers on the FTSE-250 index.
Laird, which makes electromagnetic shielding and heat-control devices for customers such as Apple Inc and Samsung Electronics Co Ltd, said it was on track to meet its full-year expectations.
The London-based company, which has increased the number of customers to which it supplies, expects its second-half results to be driven by new product launches ahead of the busiest holiday shopping season of the year.
Profit before tax rose to 16.0 million pounds ($27.04 million) for the six months ended June 30 from 10.2 million pounds a year earlier. Revenue rose 4 percent to 252.6 million pounds.
Higher profit was driven by revenue growth at the company's performance materials division, which makes products to ward off electromagnetic interference, manage heat dissipation and maintain signal quality in mobile phones and other electronics.
The company said revenue from its largest customer - which it did not identify - was flat.
Liberum analysts wrote that Laird's largest customer was Apple, and that the company's overall revenue growth was driven by "customer diversification and cross selling".
Laird declared an interim dividend of 4.27 pence per share, up from 4.10 pence a year earlier.
The company's shares were up 6.5 percent at 285.1 pence at 0809 GMT. ($1 = 0.5917 British Pounds) (Editing by Gopakumar Warrier and Robin Paxton)