They allow chips, for example in MEMS sensors, to be coated in a uniform thickness of less than 100 µm that does not extend beyond the chip edges.
Increasing miniaturisation in microelectronic packaging gives rise to new demands on the glob top materials used. For example, manufacturers of mobile phones are now demanding a maximum thickness of 0.6 mm for MEMS packages. That means that the die coating materials used to protect the chip upper side have to be as flat as possible. The use of DELO heat-curing acrylates yields convincing results, says the company, especially when a uniform and reliable coating that does not flow beyond the chip edges is to be applied to the upper side of chips.
Adhesives developed by DELO have a low viscosity and special flow properties. They can thus be processed efficiently by jetting and, compared to conventional die coating materials, make it possible to achieve a homogenous flat surface with a layer thickness of less than 100 µm using just a few drops. A further benefit is the high flexibility (Shore hardness A60) reducing the risk of stresses in the chip and the wires.
In addition to the small coating thicknesses, there is another positive aspect; the black-coloured adhesive not only protects and preserves the chip surface but also covers its logic structures. This special black-coloured adhesive also makes it possible to perfectly cover the chip corners where the layer is particularly thin. Another advantage is that the optimised flow properties allow a wide range of chip sizes to be coated.
