DELO has conducted in-house feasibility studies, electrically and mechanically connecting miniLED dice using directional conductive adhesives. The results show reliable bonding strength and high yields during on-light testing.
Due to how well-accustomed they are to these solutions the display industry still relies heavily on solder materials for interconnecting SMD components. However, as dice get smaller and smaller, with miniLED applications entering mass production and microLEDs on the horizon, isotropic conductive materials like solder will soon be unable to avoid short circuits in this scale.
This observation is what prompted DELO Industrial Adhesives, a high-tech adhesives manufacturer based in Germany, to study the feasibility of their products as a potential alternative for this dated interconnection method.
In doing its research, DELO determined that materials such as DELO MONOPOX AC268 were the most appropriate of their products to test. This material is electrically conductive in one direction, helping it prevent short circuits from occurring. That and its processing properties allowing printing masks to forgo having to have their openings shrunken for dispensing makes these materials ideal for this application.
In the feasibility study, the adhesive was applied by dipping the miniLED light into a reservoir of DELO MONOPOX AC268 adhesive, then thermode-cured at 180°C for 20 seconds. Once cured, the LED dice were then tested for operational feasibility; one singular die was fixed to one test board while another board contained several lights in a daisy chain array. Lamps on both boards illuminated without issue, short circuits being successfully avoided.
“These results prove that, indeed, adhesives are a suitable alternative to pick-and-place soldering for miniLED applications,” says Tim Cloppenborg, senior product manager for LED at DELO. “Having a new, streamlined assembly process opens doors to increased production yields as well as the expedition of newer technologies, like microLEDs, which will enable fascinating new display applications within the next decade.”
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