scope:

INTRODUCTION

The purpose of this paper is to investigate emerging chip attachment methods and define and classify the attachment methods for electronic systems designers and manufacturers today. The industry is on the threshold of the next generation of electronic packaging as the component density limitations of fine pitch technology are approached. Chip Mounting Technology is appearing on the technology horizon as a viable option to higher system densities. The name "Chip Mounting Technology" (CMT) was selected in keeping with the conventions of Through Hole Technology (THT), Surface Mount Technology (SMT), and Fine Pitch Technology (FPT) . Throughout the paper, the terms "chip" and "device" will be used interchangeably to describe the integrated circuit die.

In the past decade, active device packaging has evolved from Through Hole Technology, with component leads on 2.54mm [.100"] centers, to Surface Mount Technology with leads on 1.27mm [.050"] and smaller centers. This has recently been followed by the evolution of Fine Pitch Technology with component leads on 0.63mm [.025"] and 0.5mm [.020"] . Through these evolutions the component package which contains the silicon die, or chip, has decreased in size while lead counts have increased dramatically. The reduction in die geometries has been the result of semiconductor technology improvements, particularly lithography. The package size reduction has been made possible by improvements in assembly capabilities. Through each evolutionary reduction in package size, component density on the various substrates has increased dramatically. The next evolution will call for simply removing the package, mounting the device to the substrate, and then making the interconnections to the substrate.

We recognize that there are some advanced electronics companies who have been practicing these "new" packaging concepts for years. If it were not for their pioneering efforts, technology would come to a standstill. The objective of this paper is to simply describe, and help bring the results of those innovative packaging efforts into the mainstream of electronic package design and manufacturing.