High precision solder droplet printing technology and the state-of-the-art

The continuing drive toward more complex integrated circuits (ICs) devices having lower cost, higher inputs/outputs (I/Os), greater operating speeds, increased functions per chip, and smaller device geometry has pushed the package requirements far beyond the capability of traditional packages, such as solder paste printing (SPP). Solder droplet printing technology is low cost, non-contact, flexible and data driven, and environmentally friendly has thus been discussed as an enabling technology for precisely placing fine solder deposits onto a variety of smaller substrates. It is therefore suitable for a variety of applications including direct chip attach site preparation, three-dimensional substrates, fine line interconnect, substrate via fill, optoelectronics and many others. It would also allow manufacturing techniques that are impossible or unfeasible with current technology, such as localized replacement of solder on board, depositing solder in different thickness on the same board, or using more than one type of solder on the same board. Recently, many experiments and studies have been under investigation by several groups. In this paper, the principle of the solder droplet printing technology is introduced and recent experimental results and potential application of the technology in the microelectronics industry are also included and evaluated. (C) 2001 Elsevier Science B.V. All rights reserved.