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JUNE 2018 I PCB007 MAGAZINE 53 Table 6: Impurity analysis over bath age. and for Cl, X-ray fluorescence spectroscopy (XRF spectroscopy). Beside carbon, no other non-copper ele- ments were detected. Carbon is being incorpo- rated only in very small quantities. No signifi- cant increase in carbon content was observed as the bath aged. Physical and Thermal Properties The two most important physical properties for PCB manufacturing are tensile strength and elongation %, these properties show the toler- ance of the deposit for thermal stress. The cop- per deposit plated with additives suppressor, grain refiner, and leveler will show characteris- tic physical properties. Eq. 4 Eq. 5 Eq. 6 Tensile strength and elongation were mea- sured according to the IPC TM-650, test method standard. A stainless-steel panel was plated with the current formulation. Sam- ple strips were extracted from the plated pan- el and baked in an oven at 125°C for four to six hours. A production mechanical proper- ty test instrument was used to test the strips. The measurements were used to calculate ten- sile strength and elongation % using equa- tions 4, 5, and 6. Figure 11 shows the results at two different bath ages, fresh bath and bath age around 62 Ah/L. According to the results, properties improved with the bath age. Conclusions In summary, a new via fill chemistry is intro- duced in this paper. The formulation showed excellent via fill capability, with minimum sur- face copper. Over bath age, very low TOC was observed and insignificant foreign element up- take in the copper deposit was observed. Eval- uation of structure showed stable crystal struc- ture during aging, with a slightly preference on the (111) plane. The hardness of the plated de- posit was 79 ± 8 HV 0.05 regardless of the bath age. The physical properties, tensile strength and elongation improved as the bath aged. All the additive components can be analyzed us- ing CVS analysis. PCB007 Figure 11: Tensile strength and elongation of the plated deposit.

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