The Swedish Institute of Production Engineering Research is sponsoring the The Nordic Electronics Packaging Guideline web site. The site has a handy introduction to wire bonding that I found useful. There are guidelines on flip-chip, polymer bonding, chip scale packaging, ball grid arrays, and multi-chip modules.
Ball bond
Wedge bond
![Image](http://extra.ivf.se/ngl/images/ChapterA/Image12.gif)
Ball bond
![Image](http://extra.ivf.se/ngl/images/ChapterA/Image11.gif)
Wedge bond