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62 PCB007 MAGAZINE I JUNE 2018 FE-SEM equipped with OIM (orientation im- aging microscopy) system of EBSD after pol- ishing by CP and carbon coating. EBSD condi- tions are shown in Table 5. Results and Discussion Pattern Ability The ability to plate fine patterns is demand- ed for most of today's boards and packages. While electroless nickel plated layers serve as an excellent diffusion barrier to copper, limits are being seen for deposit thickness in many of the new board designs. Figure 2 shows the comparison of plating pattern ability between IGEPIG, EPIG, and ENEPIG deposits with pure Pd. Although ENEPIG process had over-plat- ing in the space of the wiring line and a little over-plating was observed for EPIG deposit, no over-plating was observed for IGEPIG depos- it. It seemed that the thickness of EN depos- it was main factor of over-plating while the Pd chemical activator process also had some in- fluence. Because IGEPIG process has no elec- troless nickel and activator process, the pattern ability was excellent compared to the others. Solder Joint Reliability For the evaluation of SJR for each deposit af- ter mounting the solder ball, BP was evaluated by the failure mode after pulled the solder ball as shown in Figure 3. Points were assigned to four types of failure mode. For complete bro- ken case in the solder ball, 5 points were as- signed. If the broken interface contained less than 25% IMC, 2.5 points was assigned. Final- Table 4: AES conditions. Table 5: EBSD conditions. Figure 3: Failure mode of BP and BP point for each ball. Figure 2: Optical microscope image of fine line pattern with L/S=30 µm/20 µm (a) before plating, (b) after IGEPIG plating, (c) after EPIG plating, (d) after ENEPIG plating.