the PCB Magazine

PCB-Aug2017

Issue link: http://iconnect007.uberflip.com/i/857644

Contents of this Issue

Navigation

Page 79 of 105

80 The PCB Magazine • August 2017 by Saminda Dharmarathna, Ivan Li, Maddux Sy, Eileen Zeng, Bob Wei, William Bowerman, and Kesheng Feng MACDERMID ENTHONE ELECTRONICS SOLUTIONS Abstract The electronics industry has grown im- mensely over the last few decades owing to the rapid growth of consumer electronics in the modern world. New formulations are essential to fit the needs of manufacturing printed circuit boards and semiconductors. Copper electrolytes for high throwing power applications with high thermal reliability and high throughput are be- coming extremely important for manufacturing high aspect ratio circuit boards. Here we discuss innovative DC copper met- allization formulations for hoist lines and ver- tical continuous plating (VCP) applications with high thermal reliability and throughput for high aspect ratio PCB manufacturing. The formula has a wide range of operation for cur- rent density. Most importantly, plating at high current density using this DC high-throw acid copper process offers high throughput, excel- lent thermal reliability, and improved proper- ties for present-day PCB manufacturing. The operating CD range is 10–30 ASF where micro distribution of ≥ 85% for AR 8:1 is achievable. This formulation offers bright ductile depos - its where plating parameters are optimized for improved micro-distribution and the proper- ties of the plated copper deposit such as tensile strength and elongation. The thermal reliabil- ity and properties of the deposits were exam- ined at different bath ages. Measured proper- ties are: Elongation ≥ 18% and tensile strength ≥ 40,000 psi. All the additives can be easily con- trolled by cyclic voltammetry stripping (CVS) analysis. Introduction Copper has a high electrical conductivity and is relatively inexpensive compared to oth- er high conductive metals such as silver. There- fore, the use of copper in the mass production of PCBs and semiconductors grew exponential- ly in the last few decades [1] . With today's com- plex circuit board designs an even deposition with specific physical properties is necessary to meet the standards. Especially with high aspect ratios, through-hole plating to obtain desired plating distribution is much more challenging. During the quality control inspection, a board can be rejected if there is insufficient copper on the center walls of the through-holes. More- over, plated copper should meet the minimum requirements of physical properties such as ten- sile strength and elongation (T&E) to withstand the high temperature applications [2] . ARTICLE

Articles in this issue

Archives of this issue

view archives of the PCB Magazine - PCB-Aug2017