Improved reliability with underfilled area array packages

Flip chip in package is expected to become a major solution for area array packages such as BGA (ball grid array) and CSP (chip scale package), which will represent over 20% of all flip chip devices by 2005 on a global scale. Manufacturers of portable electronic components such as mobile phones, laptops, camcorders, pagers or portable organisers are already using these packages to continue the steady reduction in size and weight. With the trends towards smaller pitch, smaller solder ball height and larger die size, the use of underfill material becomes more important. In particular, wafer level CSPs fall into this category, because they are similar to the bare chip attachment approach.