DELO Evaluates Adhesives as Alternatives to Solder for miniLED and Future microLED Applications

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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. With these findings, it is evident that adhesives refine miniLED display manufacturing, better adapting them for the mass market as well as carving a pathway for mass microLED display production.

Due to their familiarity with 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 on this scale.

This observation 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 like 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,” said 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.”

This study is just one of the many pioneering preliminary studies that DELO does to keep ahead in the many industries it serves, in addition to over 3,000 customer tests per year. The advanced materials supplier serves high-profile customers—from Infineon to Mercedes-Benz—across many sectors, including the automotive, consumer electronics, and semiconductor industries.

Experts from DELO will discuss these results at the upcoming MicroLED Connect show, the most important microLED conference and exhibition worldwide which will take place in Eindhoven, Netherlands, on September 25-26. 

Click here to learn more about DELO.

Click here to learn more about MicroLED Connect.