|MadSci Network: Physics|
You need to understand the nature of automobile glass which is 'tempered' and so requires very little force to literally 'explode'. The ceramic chip not only provides the needed energy to initiate the process, it also does so without much sound energy being formed. Layers of plastic - laminating- is used to prevent the shattered pieces from leaving each other. You can research this using Google as well, and the following webpage was useful for me http://priuschat.com/index.php?showtopic=10888
Try the links in the MadSci Library for more information on Physics.