A decade ago, device and component miniaturization of the scale we are familiar with today was unheard of, let alone anticipated. Indeed, currently, the drive towards miniaturization appears to be unstoppable, with Chip Scale Packages and Ball Grid Arrays powering this advance. However, as we move into the lead-free era, underfills are playing an increasingly important role in enhancing the reliability of lead-free CSP devices. In answer to this evolving manufacturing need, Henkel has developed Loctite® 3549, specifically formulated for use with today’s advanced CSP and BGA packages.

Research undertaken by Henkel has indicated that lead-free solder joints in area array components are more vulnerable to failures due to mismatches in the coefficient of thermal expansion. Such failures can largely be explained by the decreased ductility of the lead-free solder, combined with the increased likelihood of assembly warpage due to elevated lead-free reflow temperatures. This problem is only increased by the drive towards miniaturization.

Loctite 3549 high flow underfill is designed to address this, efficiently filling the space beneath the CSP and BGA package and curing rapidly at a low temperature in order to minimize stress on other components. This innovative material will enable manufacturers to distribute stress across the whole surface of the substrate, thereby subjecting solder bumps to lower levels of stress and reducing the possibility of failure.

Since CSP and BGA packages are being used increasingly in portable devices, which are more likely to experience drop vibration and stress, Loctite 3549 delivers exceptional protection for solder joints in these situations. In addition, the product has been tested to JEDEC drop test standards on 0.4 mm and 0.5 mm lead-free devices. This testing revealed that Loctite 3549 offers five times the reliability of non-underfilled lead-free devices.

In addition, the lead-free underfill delivers high levels of flexibility, compatible with an extensive range of modern lead-free solder materials. Plus, being completely reworkable, Loctite 3549 significantly increases the process window and ensures the recovery of high-cost substrates and PCBs. Meanwhile, a long pot-life, and simple, standard refrigeration temperature storage presents manufacturers with further production efficiencies for more confident operations.

As a consequence, Loctite 3549 is the underfill solution the industry has been waiting for completely in tune with the modern manufacturing environment. While being able to develop and support the industry’s transition to finer-pitched devices and thinner substrates, Loctite 3549 is also primed for the elevated temperatures associated with lead-free. Therefore, as part of an optimized assembly process, Loctite 3549 delivers unique process advantages – for both now and in the future.