Abstract
As advanced packaging continues to develop to support novel and emerging technologies, the need for, ideally non-destructive, test and inspection continues to be vital to ensure the quality and assurance of functionality, wherever the package may go. This is made ever more difficult as the package complexity increases, whilst the feature sizes within continue to decrease. X-ray technology has long been an important part of the non-destructive inspection protocol over the history of advanced packaging and will continue to need to play a more important part in the future. This paper will review the advances made in both 2D and 3D X-ray inspection over recent years and the new opportunities that are now starting to be available, especially in 3D, or CT, inspection, that will enable this 120-year-old technology to remain relevant to and supportive of the needs of advanced packaging.
To highlight the above, a case study will be presented on the faults that 2D and CT X-ray analysis can find in LEDs during their manufacture. LEDs are a good example of the remarkable developments in packaging and technology over the last 20 years, where the use of higher powers, smaller sized features and increased reliability requirements intensify the need for higher quality, more consistent production output. Flaws cannot be accepted, especially as higher usage powers mean higher operating temperatures which, in turn, then requires very good thermal conductivity in the package to move heat away from key areas. Without good heat dissipation then heat stresses at the interfaces can cause delamination or die fractures, so reducing LED lifetimes. The presence of voids, particularly at the die to package interface, creates air gaps that reduces heat transfer efficiency. As many LEDs are potted, or encapsulated, the only non-destructive test option to check for voiding and other faults is by using 2D and CT X-ray analysis.
Improved non-destructive 2D and 3D X-ray imaging of leaf venation
