New Die Attach Film Raises the Bar on Wetting and Molding Performance
Complexity, functionality, miniaturization and cost-efficiency have been and continue to be the mantra of the electronics industry. Arguably, no segment is more keenly aware of this fact than the semiconductor packaging sector.
As die stacks grow in number and, therefore, wafers become thinner, packaging specialists are forced to find novel materials and processes that can accommodate these demands cost-effectively. For die stacking applications that require ultra-thin bondlines and extreme uniformity, die attach film materials have emerged as one of the more robust solutions to address these device demands.
But, as die stacks have grown in number and complexity, challenges with thermal budgets, material wetting and performance during the molding process remain. For example, some films may not have good wetting performance early in the stacking and wire bonding process so wetting to the substrate is incomplete and, therefore, introduces voids into the interface. Some argue that much of the voiding can be resolved during the molding process, but reliance completely on mold pressure for void reduction is not the best approach.
Another common problem with some of today’s die attach film materials is mold compound penetration. If the film is not completely adhered – all the way to the edge -- to the substrate or die, mold compound materials can actually penetrate the die layers, which then causes interface adhesion strength to be weakened and results in package failure.
These hurdles, however, have been overcome with a new material innovation from Henkel. Materials scientists at the company have formulated a novel die attach film portfolio—the ABLESTIK ATB-100US series – that addresses the common performance requirements of modern die stacking processes while also delivering on some challenging characteristics such as wetting and molding performance.
With a very long thermal budget of four hours at 175°C or 24 hours at 150°C, the ABLESTIK ATB100-US die attach film products allow for skip curing and a thermal budget long enough to ensure sufficient wetting until the last die is stacked. In fact, the ABLESTIK ATB-100US films, while shown to be competitively superior in terms of thermal budget during internal testing, are proven to have excellent wetting with minimum voids to the substrate before molding process. With this characteristic, customers do not need to be concerned about excessive voiding that molding processes may not totally eliminate.
As skip cure materials, the ABLESTIK ATB-100US products also exhibit very good resistance to molding. While the sub-par adhesion of competitive materials may allow mold compound materials to penetrate the interface, ABLESTIKATB100US does not. This improves device yield by eliminating any risk of adhesion weakness from the introduction of mold compound materials.
Extending cost-efficiency to manufacturers as well, ABLESTIK-ATB100US films provide excellent adhesion to copper leadframes. This is an improvement over older generation materials and allows manufacturers to reduce packaging costs by employing Cu leadframes as opposed to the more costly Alloy 42. This cost/performance value is complemented by the process flexibility the materials extend to packaging firms. The die attach materials, which have been formulated for demanding stacked die memory devices such as flash memory cards, TSOPs, BGAs and LGAs, are available in either UV or pressure sensitive (PSA) release formulations and come in a variety of thicknesses ranging from 5 microns up to 30 microns.
For memory devices manufacturers who are looking for die attach films that offer all of the requisite performance characteristics of modern die attach materials with the added advantages of extended thermal budgets, superior wetting and outstanding molding performance, they need look no further than ABLESTIK ATB-100US. Once again, Henkel’s has delivered on its innovation promise.
For more information on ABLESTIK-100US or any of Henkel’s advanced die attach solutions, log onto www.henkel.com/electronics or call the company’s headquarters at 714-368-8000.