There has been some confusion around whether or not you can crawl PDFs with SharePoint Foundation 2010. The answer to the question is yes, you can, without any other products. Numerous articles and blog posts say Search Server is necessary, but fortunately it isn’t. The issue with using iFilters is that there is no mechanism in SharePoint Foundation to tell the crawler to crawl additional file types, like there was in WSS 3.0. In order to register the additional file types for crawling, you need to use a VB Script, which can be found here.
You will find powershell script to activate pdf here