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August 2015 • SMT Magazine 49 ate HoP defect in the assembly. Warpage mea- surement of the BGA across the entire tempera- ture is shown in Figure 13. According to both the JEITA (-/+0.22 mm) and JEDEC (-0.14/+0.23 mm, note that the specification does not address a 0.63 mm ball) specifications, this amount of warpage would be completely within the accept- able range. Although the study did not correlate the percentage of improvement in yield, the supplier confirmed that improvements to that same package (bringing it within the propose ac- ceptance criteria) would minimize and possibly eliminate the HoP defects. Case 6 Package description: • FBGA • 165I/O • 13 x 15 mm • 1.0 mm pitch • SnPb and Pb-free • 0.5 mm ball diameter Case 6 is considered a key example sup- porting the propose acceptance criteria. Two of the same type of BGA are used on two differ- ent products from one of the participate mem- bers. For the purposes of this paper, they will be referred to as MPN1 and MPN2. MPN1 had a different die size then MPN2. MPN1 also had the variant of MPN1A for SnPb and MPN1B for Pb-Free assembly, whereas the MPN2 used Pb- Free assembly only. Both of these BGAs caused notable incidence of HoP defects between the OEM and the EMS sites that assembled these devices. The first findings showed that MPN2 had a much higher incident of HoP defects then MPN1B (Pb-free assembly only). MPN1A and MPN1B showed HoP defects in both SnPb and Pb-Free assembly. Furthermore, MPN1 yielded HoP defects in the assembly results of five dif- ferent assembly locations. A large number of Shadow Moire analyses were performed on MPN1 and MPN2 and the data was compiled and shown in Table 2. These observation help support the propose accep- tance criteria. They also confirm that the higher the degree of warpage, the more likely the part is to generate HoP defects. For this particular part size and BGA ball diameter, the JEDEC specification allows 0.13 mm (5.1 mil) of warpage which is much tighter then JEITA specification which allows 0.22 mm (8.7 mil) warpage. Regardless, the results of this work indicate that warpage values of as little as 0.093 mm (3.7 mil) resulted in HoP defects; far below the maximum allowable warpage indi- cated in the current specifications. Table 2: Warpage measurement data of Mpn1 and Mpn2 from case 6. WARPAGE ACCEPTANCE PROPOSAL continues FeAture