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New Reworkable Underfill Adhesive for Process Control of Consumer Electronics

Posted on 8/18/2021 8:58:14 AM By ASC
  

A new underfill adhesive for consumer electronics has been launched. The company, Panacol, reports it is able to address some of the problems currently encountered during manufacture. These include stresses that occur between chips and substrates, optical inspection issues, and the lack of reworkability.

The new underfill, a heat-curing resin-based epoxy with low viscosity and linear flow behavior, allows for precise application. The company reports that the adhesive can be applied in the classic contact way using a dispenser, but because of the underfill’s uncured properties, it can also be dispensed the contactless way for precise and fast placement.

According to the company, their underfill retains the black coloring which is traditionally part of the underfill formulation for adhesives used on PCBs, so as to obscure proprietary features and enable optical inspections. However, the company reports that the dark color, along with the dark chip, shallow layer of black adhesive underfill, and the small gap between the chip and the substrate, has been known to impact on the accuracy of the measurements and inspections and the add to the time spent doing it.

Panacol reports that to address these issues, their black underfill includes a shimmering yellow fluorescence which is stimulated by short wavelength light (less than 365nm).  According to the company, the new underfill is also reworkable, allowing for complete modules or components on PCBs to be repaired or re-processed. Strategically applying temperatures above its glass transition temperature range (150◦C) can soften the underfill so that it becomes reworkable but does not reduce the adhesive’s protective function during PCB processing. 



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