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 pa ckage requirements far beyond the capability of traditional packages, such as solder paste printing (SPP). Solder droplet printing technology is low c ost, non-contact, flexible and data driven, and environmentally friendly ha s thus been discussed as an enabling technology for precisely placing fine solder deposits onto a variety of smaller substrates. It is therefore suita ble for a variety of applications including direct chip attach site prepara tion, three-dimensional substrates, fine line interconnect, substrate via f ill, optoelectronics and many others. It would also allow manufacturing tec hniques that are impossible or unfeasible with current technology, such as localized replacement of solder on board, depositing solder in different th ickness on the same board, or using more than one type of solder on the sam e board. Recently, many experiments and studies have been under investigati on by several groups. In this paper, the principle of the solder droplet pr inting technology is introduced and recent experimental results and potenti al application of the technology in the microelectronics industry are also included and evaluated. (C) 2001 Elsevier Science B.V. All rights reserved.