During the past few years, advances have been made in both in X-ray tube and detector technologies. The field of microfocus radioscopy has been established as an important testing process and has expanded into many new industrial applications that require quality control or process optimization. The first nanofocus and multifocus X-ray systems have become available with a focal spot of .5 micron. In the existing range of microfocus X-ray tubes, further improvements have been achieved as well, such as increased long term stability of intensity position constancy. Software, image processing and manipulation techniques have all progressed as well, allowing X-ray to become a formidable non-destructive inspection method for manufacturers in virtually every industry, especially those involved with Electronic Packaging and SMT.

In the case of Ni/Au finished pad on the package side, the solder joint of SnAgCu system can bring brittle fracture under impact load such as drop test. Therefore, it's difficult to prevent the brittle fracture of lead-free solder, by controlling Cu content. The failure locus existing on the interface between $(Ni,Cu)_3Sn_4\;and\;(Cu,Ni)_6Sn_5$ IMC layers must be changed to other site in order to avoid brittle fracture due to impact load. It was not found any clear evidence that there were two IMC layers exist. But it was strongly assumed these were two layers which have different Cu-Ni composition. From the above analysis it was assumed that Cu atom in the solder alloy or substrate seemed to affect IMC composition and cause to IMC brittle fracture.