Issue link: https://iconnect007.uberflip.com/i/304995
May 2014 • SMT Magazine 35 mECHaNICaL RELIaBILITy continues feATuRe As mentioned earlier, the major impact for this DOE was the use of underfill and the interac- tion with solder mask. Two types of solder mask inks have been compared; both are commonly available and released for mass production. As seen in Figure 5, the difference between the inks for samples without underfill is negligible. How- ever, in drop testing performed on underfilled parts, there was a notable difference in the drop test results between the solder mask inks. Considering that the performance of solder mask type A & B without underfill was similar, figure 1: Red = area of tension; green = strain less area; blue = area of compression. Table 3: full factorial drop test Doe. Figure 2: Schematical view of drop test boards— the four critical components are marked in red.