Board design optimization for fine pitch BGA components

Abstract

With the dominance of surface mounted technology in electronics mass production, the application of fine pitch components became common due to their small size and increasing functionality. These components are considered fine pitch, if lead pitches are equal or lower than 0.65 mm (25 mils). For Ball Grid Array (BGA) components, this value by IPC standards is considered to be around 1 mm (39 mil). Fine pitch ICs require careful approach for design, assembly and process control. Design for Manufacturing (DfM) disciples must be handled carefully by taking into account the parameters and sizes of the applied components. Layout design for fine pitch components requires customized design rules and appropriate wiring agreeing both electrical and technology demands. Fine pitch BGA components involved in a design may decrease product yield negatively if DfM rules are neglected. A test board was designed to reveal manufacturing limits of the department's PWB manufacture facility. Technology limitations are revealed by monitoring each step of the production flow. The sample board is suited for a commercial 0.65 mm fine pitch BGA component. For a very fine pitch (e.g. 0.300 mm) component, more strict rules and approaches are needed. Preliminary soldering tests were carried out with the commercially available BGA chip; however current research involves a custom, in-house designed dummy component. Component soldering is performed with a laboratory vapor phase reflow soldering station with Galden fluid. The study aims to highlight performance analyses and differences between two base board wiring conceptions as well.