Jetting technology: a way of the future in dispensing

One method used in current printed circuit board assembly is attaching components to the board with a surface mount adhesive (SMA). A small dot of adhesive is placed between two pads. Passive components i.e., 0402 can be attached to the board by jetting small dots of SMA material. The component is then placed on top of the SMA. The SMA is then cured, fixing the component in place. The experiment described in this paper attempted to reach a measure of dot size using SMA and silver epoxy materials. Small dot jetting has additional leading edge applications. The present work shows the capability of jetting material in volumes of about 3 nano-liters. The underfilling of 3D-packages with small gaps that are required to accomplish thin packages, as well as the underfilling of small die present yet another challenge to the consistency and accuracy of dispensing processes. This paper addresses the underfilling of 3D stacked die by jetting material on die surfaces with small dots to accomplish gaps of just a few microns. The challenge of jetting, abrasive materials is addressed here by monitoring, wearout evolution on the jet itself and corresponding effects on the jetted fluid characteristics. Analytical work on the fluid dynamics is presented and its predictability is demonstrated by experimental data.