TABLE OF CONTENTS C. Lazinsky
Speedline Technologies
K. Gilleo
Cookson Electronics
The area array revolution has brought on a plethora of new packaging designs, new and modified materials, innovative processes, and advanced encapsulation equipment. This chapter briefly describes the package types, provides the basics of the materials, and highlights the most common processes before going into the details of equipment for liquid encapsulation. Major advances in materials, processes, and equipment have occurred during the 1990s, and the pace of change may even be accelerating today. Dispensers are now available that apply material with vacuum injection to eliminate air. Very high capacity machines are also available that employ up to four dispensing heads that can run the same or different liquid encapsulants. All these developments have occurred while the equipment has become more robust, increasingly precise, and easier to set up.
The advent of area array packaging has greatly increased the use of liquid encapsulants and has resulted in new processes. Although transfer molding using solid epoxy molding compound (EMC) is still dominant, liquid encapsulation has become popular for many chip scale packages (CSPs) and larger plastic ball grid arrays (PBGAs). Liquids offer certain advantages that offset their slightly higher cost. Direct chip attach (DCA) assembly, better known as flip chip(FC), uses liquid dispensing almost exclusively for underfill. The next subsection will describe the basic packaging concepts and processes.
The chip-on-board (COB) process involves first attaching the bare die or semiconductor chip to a...
