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46 SMT Magazine • August 2015 Case 2 Package description: • PBGA • 484I/O • 19 x 19 mm • 0.8 mm pitch • Pb-free This case study came from a complex tele- com product that exhibited variable produc- tion yields as reported in Coyle's paper [2] . This device was reported to have a 0.104 mm (4.1 mils) negative warpage during reflow. Howev- er the paper reported a number of confirmed HoP defects, located mainly at the corners and outer rows of the BGA (consistent with the negative warpage). According to the JEITA and JEDEC specifications, this device is complete- ly within the acceptance limit of +/-0.17 mm or -0.14/+0.23 mm respectively. The example shows that the BGA is well within both of the specifications yet HoP defects were experienced in production. Case 3 Package description: • FBGA • 154I/O • 17 x 17 mm • 0.8 mm pitch • SnPb • 0.5 mm ball diameter Case number 3 was reported by the participating company as a device that caused notable HoP issues in the factory. The device was reported to have 0.119 mm (4.7 mils) of negative warpage at re- flow. Figure 11 shows the 2D and 3D plot of the warpage measurement of the BGA. Here too we see a case where a package that is well within the JEDEC (-0.14/+0.23 mm) and JEITA (-/+0.17 mm) specifications, results in HoP de- fects. figure 10: results of the warpage measurement of four bga from case 2 [2] . figure 11: 2D and 3D plot of the warpage measurement of the bga from case 3. WARPAGE ACCEPTANCE PROPOSAL continues FeAture