Numerische und experimentelle Betrachtung des Molded Underfills

Paetsch M, Nguyen TD, Dreissigacker M, Bauer J, Hoelck O, Bader V, Braun T, Zuehlke J, Minkus M, Voges S, Becker KF, Woehrmann M, Lang KD, Schubert DW, Schneider-Ramelow M (2019)

Publication Type: Conference contribution

Publication year: 2019

Publisher: VDE Verlag GmbH

Pages Range: 545-548

Conference Proceedings Title: MikroSystemTechnik Kongress 2019 - Mikroelektronik MEMS-MOEMS Systemintegration - Saulen der Digitalisierung und kunstlichen Intelligenz, Proceedings

Event location: Berlin DE

ISBN: 9783800751297

Abstract

To protect flip chips from thermal and mechanical stress caused by several environmental influences, they are encapsulated to ensure a reliable functionality. Usually low-viscosity, epoxy-based polymers are facilitated. For the conventional underfill the material flows under the die, driven by capillary forces. This is especially time consuming and prevents a high throughput. This procedure is followed by the overmould by either using transfer or compression moulding. Vacuum-assisted compression moulding allows the complete and simultaneously under-fill and overmould in only one process step. The implementation of the moulded under-fill (MUF) requires a single production machine, reduces material costs, process time and allows a higher through put. There is no need for new infrastructure and minimal in-vestments necessary for the changeover, which is an extraordinary advantage. For the MUF process an assembled substrate, containing the flip chips is inserted into the cavity, which is subsequently closed. After reaching the desired quality of vacuum the press continues to its final position and presses the EMC in the cavity, over and under the die. After a short pre-cure, the encapsulated substrate can be removed from the cavity. A problem that arrives, also for the conventional underfill, is the development of voids- the inclusions of gas between the active side of the die and substrate. The presence of voids can decrease the reliability. The dependencies on void formation regarding the variation of process and geometry parameters are only described qualitatively in literature, but not quantitatively. With the aid of a numerical model, which incorporates the specific material properties of the EMC, a basic understanding of the flow is generated allowing insight which are not accessible otherwise. The volume which is needed to be filled, is relevant for the form of the flow front. A large number of chip geometries, bump heights and package densities are analysed and evaluated under realistic process parameters and theirs applicability for the MUF. The results of this work, enable first trends and tendencies under which boundary conditions the MUF is successful to reduce efforts and costs.

Authors with CRIS profile

Dirk Schubert Lehrstuhl für Werkstoffwissenschaften (Polymerwerkstoffe)

Involved external institutions

Technische Universität Berlin DE Germany (DE) Fraunhofer-Institut für Zuverlässigkeit und Mikrointegration DE Germany (DE)

How to cite

APA:

Paetsch, M., Nguyen, T.D., Dreissigacker, M., Bauer, J., Hoelck, O., Bader, V.,... Schneider-Ramelow, M. (2019). Numerische und experimentelle Betrachtung des Molded Underfills. In MikroSystemTechnik Kongress 2019 - Mikroelektronik MEMS-MOEMS Systemintegration - Saulen der Digitalisierung und kunstlichen Intelligenz, Proceedings (pp. 545-548). Berlin, DE: VDE Verlag GmbH.

MLA:

Paetsch, M., et al. "Numerische und experimentelle Betrachtung des Molded Underfills." Proceedings of the MikroSystemTechnik Kongress 2019: Mikroelektronik, MEMS-MOEMS, Systemintegration - Saulen der Digitalisierung und kunstlichen Intelligenz - MikroSystemTechnik Congress 2019: Microelectronics, MEMS-MOEMS, System Integration - Pillars of Digitization and Artificial Intelligence, Berlin VDE Verlag GmbH, 2019. 545-548.

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