A Review of the Economics of Embedded Passives

This paper provides an overview of the economic issues and cost models associated with the conversion of discrete passives to embedded passives in printed circuit boards. Three attributes of economic analysis are included herein: fabrication and manufacturing cost analyses, embedded resistor trim and rework economics, and non-manufacturing life cycle costs that are impacted by the conversion of discrete passives to embedded passives. In addition, a complete set of references to existing work on the economics of embedded passives is provided. INTRODUCTION Economics encompasses an assessment of the total life cycle cost of a design decision where the life cycle includes the design, manufacturing, testing, marketing, sustainment, and end-of-life of the product. The decision to convert discrete passives to embedded passives is much further reaching than simply reducing the cost of part procurement and paying more for the board. In addition, there are a host of other cost and benefit issues to be considered that translate into life cycle economics at some level. This paper reviews the economic attributes of a system’s design and production that impact the decision to use embedded passives and outlines existing models for addressing economic tradeoffs. Embedded passives are fabricated within substrates and, while embedded passives will never replace all passive components, they provide potential advantages for many applications. The generally expected advantages include: • Increased circuit density through saving real-estate on the substrate • Decreased product weight • Improved electrical properties through additional termination and filtering opportunities, and shortening electrical connections • Cost reduction through increasing manufacturing automation • Increased product quality through the elimination of incorrectly attached devices • Improved reliability through the elimination of solder joints. Potentially the biggest single question about embedded passives is their cost, "...of all the inhibitors to achieving an acceptable market for integral substrates, the demonstration of cost savings is paramount" [1]. There is considerable controversy, however, as to whether applications fabricated using embedded passives will ever be able to compete economically with discrete passive technology. On the bright side, the use of embedded passives reduces assembly costs, shrinks the required board size, and negates the cost of purchasing and handling the discrete passive components that are replaced. However, these economic advantages must be traded off against the higher cost (per unit area) of boards fabricated with embedded passives (a situation that will not disappear over time) and possible decreases in throughput and yield of the board fabrication process. The application-specific costs depend on many effects when embedded passives are present in a board: • Decreased board area due to a reduction in the number of discrete passive components • Decreased wiring density requirements due to the integration of resistors and bypass capacitors into the board • Increased wiring density requirements due to the decreased size of the board • Increased number of boards fabricated on a panel due to decreased board size • Increased board cost per unit area • Decreased board yield • Decreased board fabrication throughput