Printed Circuit Design & Fab - May 2008 - (Page 19)

bath. Thus, the chemical composition The historic preference for electroplating relates of the predip and its level of contamito the LOWER COST, FASTER DEPOSITION RATE, nants are critical. AND THE GENERALLY BETTER METALLURGICAL Critical parameters of the acid copper bath include electrical, mechaniPROPERTIES of the electroplated copper. cal, physical, and chemical variables. Starting with the electrical parameters, current density and primary current density distribution affects plating rate, thickness across the the electrodeposition process, and the influence of process board surface, and the metallurgical properties (e.g., ductilparameters will be discussed in future columns. The degree ity, roughness and color) of the deposit. The current density of difficulty for plating through-holes depends on board across the plating surface depends on the rectifier capacity, thickness as well as hole diameter. For example, given a related anode and cathode sizes, as well as spacing, shieldchoice of two holes, both with a 10:1 aspect ratio, the prefing, cell efficiency, and solution conductivity. The current erence would be to design a 100 mil thick panel with a 10 density distribution across the plating surface depends on mil via diameter, versus a 200 mil thick panel with 20 mil several of the previously mentioned factors and, in the case diameter holes. of pattern plating, also on the circuit pattern. The current FIGURE 2 underscores the difficulty in maintaining density in the through-hole depends on the following addithrowing power as the aspect ratio increases. Figure 2 illustional variables: trates that the IR drop (or the electrical resistance through the via) increases as a squared factor, while via diameter ■ Through-hole diameter and aspect ratio only effects the resistance (or throwing power) in a linear ■ Replenishment efficiency of plating solution (agitation) fashion. ■ Throwing power of the bath, which is largely determined by the acid/copper ratio, the organic plating additives, In Part 2, we will continue to explore the electrodeposiand the level of impurities (organic and inorganic) that tion process. PCD&F interfere with the organic plating additives. In FIGURE 1, throwing power is defined for purposes MICHAEL CARANO is vice president for OM Group Inc. and of this and subsequent columns. The actual mechanics of can be reached at mike.carano@omgi.com. “Ventec laminate has been a tremendous asset in Titan PCB East’s ability to provide a high quality, high reliability lead free product to today’s time critical, cost sensitive market. Ventec VT-47 provides superior peel strength, high Td, Z-axis stability, thermal reliability, surface quality and inventory selection all in the same package. The fact that this is provided in a cost competitive manner is icing on the cake. Ventec is not just a player in the game, they are a top performer. The addition of VT-90 polyimide materials to the FR-4 offerings make Ventec a force to be reckoned with in the future.” Mike Berg, President and CEO, Titan PCB East – Amesbury, MA “When using the VT-47 and VT-481 materials, we have found above average drill and scoring characteristics without experiencing the fracturing and haloing associated with other well-known lead free comparable phenolic resin systems.” John Gratton Engineering Manager Century Circuits – Toronto, ON “We have been very pleased with the quality, service, performance, and consistency of the Ventec materials for almost two years now. I would not hesitate to recommend Ventec VT-47 to our customers as a reasonably priced alternative for lead free assembly.” Robert E. Welch Process Engineering Manager Waytec Electronics Corp. – Lynchburg, VA “The family of Ventec laminates has made an improvement in our processing of multilayer circuits. The materials exhibit very good consistency. Our quality department is very satisfied with the performance of these laminates.” Jim King Process Engineer Philway Products – Ashland, OH Global Laminates Inc. 16 Hunt Rd. South • Amesbury, MA 01913 • (978) 388-9610 • (978) 388-5339 fax • www.globallaminates.com Sales reps and distributors wanted: email Bruce at bhurley@globallaminates.com MAY 2008 PRINTED CIRCUIT DESIGN & FAB 19 http://www.globallaminates.com http://www.globallaminates.com

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

Printed Circuit Design & Fab - May 2008 Contents Our Line Market Watch Around the World Happenings ROI EMC For the Real World PCB East Conference Brochure Positive Plating Don't Let your Signals Stub Their Toes Improve PCB Layout With Skill Utility Programs The Next Generation Design Tool Challenge Thermally Conductive Microwave Materials PCB Dielectric Degradation in Lead-Free Assembly Applications A Tale of Two Trade Shows Eliminating Board Defects Off the Shelf Marketplace Ad Index BGA Bulletin

Printed Circuit Design & Fab - May 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.