Reuse Electronic Components with New Underfill Adhesive

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The new underfill adhesive is reworkable despite its black colour.

The new Structalit 5751 adhesive developed by Panacol allows manufacturers to reduce both manufacturing costs and environmental impact by reusing electronic components mounted on PCBs.

Underfill Structalit 5751 seen under normal daylight and yellow fluorescing under UV light. Credit: Panacol

To reduce stress between the chip and substrates, chips are attached directly to the interconnection points without any intermediate elements. Underfill technology was developed to counteract these stresses that arise at the solder bumps when the electronic modules are heated and cooled during operation. 

Structalit 5751 is a resin-based epoxy adhesive characterized by its low viscosity and linear flow behaviour.  This enables precise application. Structalit 5751 also allows contactless dispensing for fast and precise placement of the adhesive. This underfill has low iron content and is ideally suited for electronic component packaging.

Usually, adhesives are black in colour for the proprietary features and for optical inspection. Optical measurement is an integral part of a PCB manufacturing process. However, the dark chip, the shallow layer thickness of the black adhesive and the tight gap between the chip and the substrate, make optical measurement difficult. 

Panacol has addressed this problem by incorporating an additional yellow shimmering fluorescence to the black colouration of Structalit 5751. It can be stimulated by short-wavelength light of <365nm. This makes it even easier for manufacturers to perform final inspections and speeds up production processes.

In addition to the performance and optical inspection capability of Structalit 5751, Panacol also offers reworkability, another important property. This provides the ability to re-process or repair products after assembly. Especially when the pressure today is high to minimize electronic waste, this is a great step towards achieving that. 

Structalit 5751 can be strategically softened at specific adhesion points by applying temperatures above its glass transition temperature range of 150°C. The product becomes reworkable only when this critical temperature threshold is reached.  The workability temperature does not reduce the protective function of the Structalit® 5751 during typical PCB processing.  It withstands temperatures associated with reflow soldering and additional thermal curing cycles.

With the global shortage of chips, the reuse of components makes a huge difference which can be beneficial for not only the environment but also supply chains to recover from the situation.

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