The accurate prediction of the operating temperatures of critical electronicparts at the component-, board- and system-level is seriously hampered by thelack of reliable, standardised input data. The DELPHI project is addressing thisproblem by the development and experimental validation of thermal models of avariety of `generic’ electronic parts.
DELPHI (which stands for DEvelopment of Libraries of PHysical models for anIntegrated design environment) is a three-year project awarded under themicro-electronics domain of the Esprit III work programme. The project commencedon November 1, 1993, and is due for completion in November 1996. It involves 278man-months of work. The cost is 4 million ECU (approximately $5M), 50% funded bythe European Union. The project Consortium Partners consists of a mix ofindustrial companies manufacturing a range of electronic equipment, a softwaresupplier and a university-linked research institute, namely: Alcatel Bell(Belgium); Alcatel Espace (France); Philips CFT (Netherlands); Thomson CSF(France); Flomerics (UK); and NMRC (Ireland). The project coordinator isFlomerics.
The parts studied fall into the following categories: plastic mono-chippackages (PQFP, PLCC, PPQFP, PBGA, PDIP, TSOP, SSOP, TSSOP); ceramic mono-chippackages (CPGA, CDIP, CERQUAD, LCCC, CQFP, CBGA); specific parts (MCM,chip-on-board, T0220, T03); passive parts (electrolytic capacitor, transformer);air flow parts (perforated plates, axial and radial fans); heat transferenhancers (various heat sink styles); interfacing materials (pastes, dieattach). The creation of thermal models of these parts, correct for the intendedrange of thermal environments they are likely to encounter in applications, is anon-trivial exercise: the possession of thermal CAD software is only a smallpart of what is needed. In DELPHI, the best methodologies for model buildingare being established. For all parts considered, two kinds of thermal model areconstructed: a detailed (or full) model and a compact model. For example, for amono-chip package the detailed model consists of a detailed conduction modelcontaining several thousand computational nodes, whereas its compact modelequivalent is a thermal resistor network containing no more than 10 (say) nodes.
DELPHI will achieve its full potential when the suppliers of the parts, ie.the component manufacturers, supply with their hardware thermal models of theirparts in some generic format. A portion of project funds are allocated fordeveloping links with component manufacturers and international standardizationbodies: for example DELPHI plays an active role in the deliberations of theJEDEC committee JC15.1. An outcome of DELPHI is a methodology for adoption bycomponent manufacturers, which will enable them to produce validated thermalmodels for passing on to their customers. Here DELPHI defines a boundary toseparate the ‘thermal responsibilities’ of the component manufacturer from thoseof their customers: the component manufacturer is responsible for the thermalmodel of the part and nothing else; and the end user is responsible for thespecification of the thermal environment to which the part is exposed (ie. theconvective, conductive and radiative heat transfer from the surface of the partand through its leads).
For the component manufacturer, DELPHI provides: a methodology forgeneration of compact models (from the detailed models) valid for a very wideset of thermal environments; and two novel experimental procedures (the doublecold plate method and the submerged double jet impingement method) used tovalidate the detailed models. For the equipment manufacturer, DELPHI provides(within Flotherm) validated generic models of a range of electronic parts (eg.chip packages, fans, heat sinks, etc..) in either a detailed or compact modelformat.
For further information consult:
“Delphi – a status report on the European Union Funded Projectfor the Creation and Validation of Thermal Models of Electronic Parts”, H IRosten, Thermal Management of Electronic Systems, Proc. of Eurotherm Seminar29, 20-22 Sept. 1995, Leuven, Belgium.
H. I. Rosten, Technical Director, Flomerics Limited, 81 BridgeRoad, Hampton Court, Surrey, KT8 9HH, UK