Delo has developed a special microelectronics adhesive for the rapid assembly of micro dams, i.e. very fine microstructures, in semiconductor packaging or on circuit boards, which opens up new possibilities in heterogeneous integration and optical packaging.
The special adhesive Delo Dualbond EG4797 can be used to create very fine free-form structures and optical barriers. Microstructures can serve as flow stops, for example, and reduce so-called keep-out zones. These areas are provided in the PCB layout to limit the flow of underfill adhesives for solder contacts and thus protect surrounding components. In optical packaging, micro dams act as ultra-fine optical barriers.
The newly developed adhesive is a halogen- and solvent-free acrylate that can be used to produce lines of less than 100 µm in width with an aspect ratio of five or more. Line widths of 200 µm were previously considered a challenge. The adhesive was developed in close cooperation with a corporate partner, the system manufacturer NSW Automation, which produces micro-dispensing units for the semiconductor industry.
The special feature of the adhesive is its high thixotropy index of 6.6, which indicates the ratio of the viscosity of two different flow rates of an adhesive. As a result, Dualbond EG4797 can be dispensed at a speed of 15 mm/s and more. This creates a stable microstructure layer by layer on flat and curved surfaces.
The adhesive is dispensed and applied using conical needles with a diameter of 100 µm. The structure is then cured in a single step and with minimal energy input. The adhesive can be cured either with UV radiation in ten seconds or thermally in five minutes at +120 °C. Another option is a dual curing process using UV light and heat.
The adhesive won the 2024 Global SMT Global Technology Award for Semiconductor Packaging Adhesives. Delo will be presenting its products at the LOPEC 2025 trade fair in Munich in Hall B0, Stand 516.
