“Software” is of course a very broad topic, but design and simulation is probably what comes to mind most often when the term is used in our industry. There have been some amazing advances in the capabilities of these tools, although there is still plenty of evidence that reminds us of their limitations.
Impressive Simulation Capabilities
The use of software in solving engineering challenges is increasingly pervasive. I paged through the proceedings of the International Electronics Manufacturing Technology (IEMT) symposium this year to get a feel for how software is being used, but it would have been easier to spot the few papers that didn't use advanced software somehow.
A paper from ASE used finite element analysis to correlate power cycling and thermal cycling fatigue. A paper from MicReD in Budapest used compact dynamic thermal models to evaluate the quality of die attach in stacked die packages. Credence discussed design-for-test software to improve time-to-market. Johnstech and Agilent presented a joint software-based effort to optimize test equipment and contactors to optimize yields. MicroFabrica and SolidWorks discussed how to use mainstream software for design and analysis of MEMS. The scope went far beyond the stress analysis, thermal modeling, and electrical parasitic calculations that are commonplace now.
Limitations
Although the current capabilities of analysis tools are impressive, simulation still cannot match the ultimate accuracy of measurement. The authors of a recent paper in an IEEE journal went to great lengths to show that critical product decisions should not be based solely on simulations.
The June 2004 issue of the IEEE Transaction on Components and Packaging Technologies featured that intriguing article, titled “Numerical Prediction of Electronic Component Operational Temperature: A Perspective.” The authors, from Electronic Thermal Management, CALCE, and Dublin City University, performed some very detailed analysis of the predictive ability of thermal models. Using the latest techniques in computational fluid dynamics (CFD), they showed that there can be significant differences between modeled and measured results for board-mounted components. The main conclusion is that measurements are still required for strategic product design decisions.
The complete list of conclusions in the paper cited above amplifies this point. For example, the authors noted that the accuracy of models of real systems is less than models of standard test cases. The complexity of 3-D flow conditions is greater in actual systems, which decreases the accuracy of the models.
There were other detailed technical conclusions in the paper, and a resulting outcome was the need for thermal analysis specialists to stay involved in the process. The ability to put CFD-scale computation power in any computer doesn't mean that anyone can now do good thermal analysis. Building CFD models, defining grids, and obtaining sound solutions still requires significant expertise in the field.
Software as Product Differentiator
Beyond the design and analysis realm, software is becoming a more prominent factor in process equipment as well. For example, at SEMICON West this year, Phoenix X-Ray announced automated software modules to simplify solder joint inspection and pass/fail determination in QFP and MLF style packages. The company is highlighting software rather than hardware capabilities to differentiate its product.
Recent literature from V.J. Electronix, a provider of X-ray inspection equipment, also focuses on software capability. It cites “advanced defect enhancement” software as an innovation for high-accuracy X-ray microscopy. The latest announcement from August Technology also highlights the company's purchase of defect data management software from Inspex for its inspection and metrology systems.
The trend should be clear. More and more often, software capability is the deciding factor in equipment selection.
The Future
Where will software take us in the packaging industry? I think that the lesson of the IEEE paper mentioned earlier will be a perpetual one. Software advances will continue in design and simulation, and in equipment as we've seen here as well, but the subtleties of what we are trying to do as an industry will stay a step or two ahead of software developers. Human expertise and insight will still be required for the best solutions to our engineering challenges.
 |
JEFFREY C. DEMMIN, director of product marketing, may be contacted Tessera Technologies Inc., 3099 Orchard Dr., San Jose, CA 95134; (408) 383-3691; e-mail: [email protected].