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August 2015 • SMT Magazine 41 mitigation will help to eliminate 70–90% of the HoP defects. Furthermore, in process, X- ray inspection will only detect approximately 90% of the remaining HoP defects on the as- sembled products. Thus, there is an expectation that a percentage of HoP defects (albeit greatly reduced) will still escape inspection and end up on the final products. From the authors' perspective, each of these compromised joints is likely to become a cus- tomer field failure. As a minimum field failures are both costly and damaging to the reputation of the OEM, at the other extreme, in life sus- taining and mission critical applications these failures can be catastrophic. The new accep- tance criteria seeks to address the root cause of the issue, allowing the HoP escape rate to fur- ther decrease to near zero. Current Specifications Two industry standard bodies provide re- quirements for BGA component warpage: Ja- pan Electronics and Information Technology Industries Association (JEITA) and Joint Elec- tron Device Engineering Council (JEDEC). JEI- TA ED-7306 [5] is considered to be the earliest specification the authors could locate and at one point the only standard for dynamic warp- age. In 2009, JEDEC released a similar standard Publication 95, SPP-024 Issue A [6] for dynamic warpage requirements. In both specifications, the warpage require- Figure 2: Mitigation through reflow profile adjustment [4] . figure 3: Mitigation through paste type. figure 4: aXi inspection for Hop defect. WARPAGE ACCEPTANCE PROPOSAL continues FeAture