Printed Circuit Design & Fab - August 2008 - (Page 41)

PlatinG ■ ■ Throughput Equipment cost, complexity and footprint. Copper electroplating process equipment can be generally placed in two broad categories: vertical batch or continuous conveyorized processes. In conventional vertical batch electroplating systems, a number of panels are mounted on a single flight bar and processed in a single vertical plating cell for the full duration of the plating cycle. In conveyorized electroplating systems, the panels are dynamically transported through a series of plating cells. Continuous conveyorized processes can be further divided into horizontal and vertical systems. While both individual panels and continuous web flex circuits may be processed in such types of conveyorized equipment, this article will focus on processing individual HDI substrates, rather than the use of specialized reel-to-reel equipment for flexible circuit manufacture. Vertical Batch vs. Conveyorized Equipment With conventional vertical batch electroplating systems, increased production throughput may be realized by increasing the number and/or the size of the plating cells. When the size of a plating cell is increased, the number of panels within the cell increases proportionally. Depending on the specific design and dimensions of the plating cell, panels may be placed in either single or multiple rows on a flight bar. Unfortunately, this increased panel loading leads ! fiGurE 3. PAL, MCP-PAL™ vertical continuous plating line. ! fiGurE 4. Applied equipment Ltd., vCP (vertical copper plating) equipment. AUGUST 2008 to decreased plating uniformity, particularly when comparing panels from the center of the flight bar with those from the ends. In contrast, the use of either horizontal or vertical conveyorized equipment promotes increased consistency, as each panel “sees” the same overall flow and current distribution as it passes through the equipment. The improvements in consistency can be seen in both better surface thickness distribution and enhanced uniformity of throwing power and via filling, both within a panel and from panel-to-panel. However, when side-toside variation within a panel is considered, vertical continuous systems hold a significant advantage in that only vertical systems allow the two sides of the panel to be processed in equivalent physical environments. VIL equipment designs are particularly suitable for via filling applications since the vertical panel orientation minimizes air entrapment and associated skipped or partially filled vias. In contrast, these defects can be problematic on the bottom-side of panels processed in horizontal equipment. Conveyorized systems have an overwhelming advantage over conventional vertical batch systems when it comes to handling thin-core material. For ultra-thin material, horizontal systems may hold a slight handling advantage over VIL plating systems. When system cost and footprint are considered, VIL equipment affords considerable advantages versus horizontal designs of similar capacity. Additionally, more advanced multiple track VIL equipment designs are being offered, which provide both conventional conformal plating and via filling capability in a single process line. printEd circuit dEsign & faB YOU’RE 41 http://www.photoplot.com

Table of Contents Feed for the Digital Edition of Printed Circuit Design & Fab - August 2008

Printed Circuit Design & Fab - July 2008 Contents Our Line Market Watch Around the World Happenings ROI Tip Jar Software Performance Interconnect Strategies Final Finish Forum Product Development Challenges in a Global Market Innovative Modeling Supports Co-Design of the Power Supply Chain, Part 2 Low-Loss Fluoropolymer Copper Clad Laminate Qualifying PCBs Outsourced in Asia Copper Plating and Microvia Fill for Advanced PCBs Off the Shelf Marketplace Ad Index BGA Bulletin

Printed Circuit Design & Fab - August 2008

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