Issue link: https://iconnect007.uberflip.com/i/1524755
58 SMT007 MAGAZINE I AUGUST 2024 the chance of an early failure increases with an increase in extreme hot temperature. Failure Analysis e latest version of IPC-9701 8 section 6.2, is dedicated to failure analysis and procedures. As is normal, IPC-9701 categorizes failure analy- sis methods into non-destruc- tive techniques such as electri- cal probing, visual inspection, X-ray analysis, and C-mode scanning acoustic micros- copy (CSAM), and destruc- tive techniques such as micro- sectioning (IPC 9241) and dye-and-pull (IPC-TM-650 Method 2.4.53). As empha- sized by the standard, failure analysis should always begin by using non-destructive meth- ods, with destructive analy- sis techniques only brought to bear later. e exact selec- tion of non-destructive and destructive techniques will vary depending on the specific assembly design and configu- ration. In terms of destructive FA techniques, dye-and-pull provides an easy method to find the general location of failed solder joint(s) within a package. However, it does not provide detailed information regarding failure mecha- nism and mode. Cross-sectioning can provide more details about the failure mode, as well as the location of failure within a solder joint. For this test, in addition to continuous daisy- chain resistance monitoring, computed tomography (CT) and failure analyses (FA) were per- formed. CT was performed on a failed BGA228 to determine the location of the failure before performing destructive analysis. Dye-and-pry and cross-section- ing were then performed at these locations to further visualize the location of fracture interface in a sectioned plane. Figure 7 shows the location of interest based on the CT images (area of interest found to be in the middle row of solder balls). Figure 5: Resistance monitoring graphs with two failures for CTBGAs and no-failure for CABGA208. Figure 6: Weibull Comparison of CTBGA228 for [-40°C+105°C] and [-105°C,+40°C].