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The latest IDTechEX research report ‘Electronically Conductive Adhesives 2016-2026’ assesses the major categories of safe and environmentally friendly conductive adhesives alternatives.
Each year, $1.2 billion worth of electronic conductive adhesives (ECAs) are sold that are becoming common replacements for tin-lead solders in a variety of applications, functions and industries.
ECAs contain a polymeric resin, such as silicone, that provides adhesion, mechanical and impact strength, and a metal filler that conducts electricity. To reduce the amount of filler used, research into nanoparticle fillers has been conducted, such as the use of silver nanowires, nickel nanoparticles and carbon nanotubes.
Additionally, thermal conductivity in ECAs must also be high enough that components do not overheat. They must have good adhesion to mating surfaces and have strong tensile strength. Viscosity must be low enough for easy dispensing but high enough after curing to avoid pump out and dry out. In terms of temperature, solders can operate up to 270°C whereas ECAs only operate around 200°C. The materials must also be non toxic.
Where lead solder melts at 215°C, isotropic conductive paste can be cured (hardened) as low as 110°C which creates possibilities for using plastic substrates for new generation of flexible electronics.
Presently, 74 per cent of anisotropic conductive film (ACF) is used in the production of OLED and LCD displays. As displays are becoming more readily used in the consumer electronics, automotive and defence industries, UV thermal cure mechanisms must be developed to lower cure temperature (which hardens polymers) to then allow plastic substrates for flexible displays. The IDTechEx report states that the market for displays will diversify, as ACF use in non-display applications it set to reach over $1billion by 2026 due to its thinness, reliable properties and ease of processing.
ECAs can be used for a range of applications including photovoltaic modules, and LCD and OLED displays. They can also be used in touch panels, LEDs and RFID chips.