12/01/2010, Irvine, California

 

RoHS Means Big Changes for Power Devices. Are you Ready?

While design and assembly of today’s smaller, higher functioning semiconductor devices continues to be challenging, addressing the thermal requirements of modern power packages from a materials point of view is arguably one of the most pressing issues facing this market sector.

The drive toward greater functionality in an ever more miniaturized footprint has accelerated materials innovations so that these essential components of countless consumer and automotive products can continue to provide the reliability and performance to which we have all become accustomed. As if this weren’t enough, the 2014 deadline for RoHS compliance is also looming and adding even more complexity to the materials equation. Though the possibility still remains that exemptions, exceptions and/or extensions may apply to the power device sector, it is critical that packaging specialists have a compliance plan in place.

Making future RoHS compliance a little less complex, Henkel has developed a portfolio of materials for the power device market that offer process latitude, outstanding performance and in-field reliability. Let’s first start with the current status of die attach materials. High-lead soft solders are arguably the most widely used die attach materials for power semiconductor packages. For high power passive and discrete components, such as TO 220s and the like, solder’s ability to manage the thermal load is undisputed.

But, the 2014 RoHS deadline has packaging specialists eagerly planning for future altern atives. Fortunately, Henkel has developed Multicore DA100, a flux system that is versatile enough for today’s high-lead die attach solder applications while also providing a true drop-in replacement for tomorrow’s lead-free requirements. This novel material provides the lower cost, higher conductivity advantage of solder in addition to delivering consistent cleanability, reliability, dispensability and void-free interconnects. What’s more, the flux system enables an easy transition from high-lead to lead-free die attach solders, allowing packaging firms to make an alloy change quickly and easily. Multicore DA100 is highly adaptable, with excellent wetting to copper, NiPdAu and Ag finishes. The material has also exhibited very low voiding, with void averages of less than 5%. So, for manufacturers that wish to maintain a solder die attach process, Multicore DA100 is the clear choice – both for today and the future.

Though solder is currently the leader and Henkel’s Multicore DA100 offers a clear path for compliance, some packaging specialists are also evaluating the use of conductive die attach adhesives for power package assembly. Newer silver-based systems have improved on older generation die attach adhesives and offer exceptional performance and reliability while enabling RoHS compliance. Henkel’s Hysol QMI529HT-LV is a case-in-point.

Formulated for use with power packages that incorporate small die, Hysol QMI529HT-LV provides excellent in-package electrical and thermal capability. Internal testing concludes that this material offers the best thermal resistance of any commercially available organic die attach adhesive, while also delivering proven high reliability performance. With outstanding adhesion on Au and PPF surfaces, Hysol QMI529HT-LV enables the process latitude required by power device manufacturers. In addition, the material maintains a low modulus to limit package warpage and also offers good dispensing performance.

Not only are paste die attach adhesives addressing the future production requirements for power devices, but a breakthrough conductive die attach film developed by Henkel has the potential to dramatically alter the future of the power package market. Until now, the benefits of die attach films – thinner, more uniform bondlines, improved yields, thin die processing capability, elimination of die tilt and much more – have been limited to non-conductive processes. Henkel’s new conductive film, Ablestik C100, now allows manufacturers of leadframe, power devices to enjoy the same advantages.

Following die attach, of course, comes the critical mold compound process where optimized materials are essential to ensuring a highly reliable final package. These materials are also subject to RoHS regulation and this move to “green”, halogen-free mold compounds has made materials formulation even more challenging. Again, the materials scientists at Henkel have delivered. Designed for the demanding needs of devices destined for use in automotive applications, Hysol GR725LV-2 has excellent MSL 1 260°C performance with power SO packages. With outstanding High Temperature Storage Life (HTSL) performance at 200°C over 2,000 hours, Hysol GR725LV-2 offers the robust characteristics necessary to address high-reliability power devices – all in a sustainable, halogen-free, RoHS-compliant formulation.

Navigating the terrain of the power semiconductor device market can be tough -- especially in a RoHS context. But, the materials experts at Henkel have alleviated the guesswork by providing multiple, proven in-package materials options for today’s power products and tomorrow’s regulation. From current high-lead soft solders with adaptable flux systems to silver-based conductive die attach adhesives all the way through to green mold compounds, Henkel is enabling the smaller, more powerful RoHS-compliant future of advanced power devices.

For more information on any of Henkel’s RoHS-ready die attach or mold compound solutions, call the company headquarters at 714-368-8000 or visit us at www.henkel.com/electronics.