India has imposed a 10 per cent tax on imports of key smartphone components including populated printed circuit boards, which are at the heart of smartphones, according to a government document.The government's move on Monday confirmed a Reuters report from last week that the country was exploring new duties on the imports of populated printed circuit boards that include components such as processors, memory and wireless chips.A 10 per cent customs tax was also imposed on the imports of camera modules for phones and connectors.