THE PRACTICAL APPLICATION OF PHOTO-DEFINED MICRO-VIA TECHNOLOGY
Author: Brian J. McDermott Company: Continental Circuits Date Published: 4/28/1997
Surface Mount International
Abstract: With continually increasing functionality, these are the requirements for current and future consumer electronic products in the mobile communications, computing and digital imaging markets. The transition to smaller packages with finer pitches and ultimately to area array chip scale packages (CSPS) has taken off in Japan and is happening more slowly in the US. The combined availability of packaging technologies and high density PCB technologies, that meet total cost goals for the product will determine the speed at which these design solutions are adopted in the US. This paper will focus on the PCB technologies that enable the adoption of smaller pitch, area array semiconductor packaging, to meet the form factor and functionality requirements of current and future consumer electronic products. The paper will describe the design limitations of conventional mechanical drilling of PCB’S and the design benefits of microvia technology. It will describe the process for application and via formation using epoxy based photoimageable dielectrics. The paper will provide detailed photographs of PCB’s at each stage of manufacture. It will provide testing and reliability data for products built with PhotoLinkTM technology to-date. The presentation will provide a review of the trade-off’s between alternative processes of forming microvias and determine which are likely to demonstrate the lowest cost and the highest reliability.