Fraunhofer-Institut für Zuverlässigkeit und Mikrointegration IZM

Filters
4
Reset filters

Settings
Now showing 1 - 4 of 4
  • Publication
    Fluxless flip chip bonding on flexible substrates
    ( 1996)
    Zakel, E.
    ;
    Aschenbrenner, R.
    ;
    Azdasht, G.
    ;
    Klöser, J.
    ;
    Reichl, H.
    During the last few years an increasing number of flip chip (FC) interconnection technologies have emerged. While flip chip assembly offers many advantages compared to conventional packaging techniques, several aspects hinder this technology from entering the high volume market. Among these are the availability of bumped chips and the costs for the substrates, i.e. ceramic substrates with closely matching coefficient of thermal expansion (CTE) to the chip, in order to maintain a high reliability. Only recently, with the possibility of filling the gap between chip and organic substrate with an encapsulant, was the reliability of flip chips mounted on organic substrates significantly enhanced. This paper presents two approaches to a fluxless process, the one based on soldering techniques using the Au-Sn metallurgy and the other on adhesive joining techniques. Soldering is performed with a thermode and with a laser based system. For both of these FC-joining processes, alternative bump metallurgies based on electroplated gold, electroplated gold-tin, mechanical gold and electroless nickel gold bumps are applied.
  • Publication
    Fluxless flip chip bonding on flexible substrates
    ( 1995)
    Aschenbrenner, R.
    ;
    Zakel, E.
    ;
    Azdasht, G.
    ;
    Klöser, J.
    ;
    Reichl, H.
    During the last few years an increasing number of flip chip (FC) interconnection technologies have emerged. While flip chip assembly offers many advantages compared to conventional packaging techniques, several aspects hinder this technology from entering the high volume market. Among these are the availability of bumped chips and the costs for the substrates, i.e. ceramic substrates with closely matching coefficient of thermal expansion (CTE) to the chip, in order to maintain a high reliability. Only recently, with the possibility of filling the gap between chip and organic substrate with an encapsulant, was the reliability of flip chips mounted on organic substrates significantly enhanced. This paper presents two approaches to a fluxless process, the one based on soldering techniques using the Au-Sn metallurgy and the other on adhesive joining techniques. Soldering is performed with a thermode and with a laser based system. For both of these FC-joining processes, alternative bump metallurgies based on electroplated gold, electroplated gold-tin, mechanical gold and electroless nickel gold bumps are applied.
  • Publication
    Fluxless flip chip bonding on flexible substrates
    ( 1995)
    Zakel, E.
    ;
    Aschenbrenner, R.
    ;
    Gwiasda, J.
    ;
    Azdasht, G.
    ;
    Ostmann, A.
    ;
    Eldring, J.
    ;
    Reichl, H.
    ;
    Klöser, J.
    Flip chip (FC)-technology on flexible circuits is of increasing interest for application in consumer oriented products. In particular, fluxless processes are in demand for compatibility with underfill materials and for improved reliability performance. This paper presents two approaches to a fluxless process based on soldering techniques using Au-Sn metallurgy and on adhesive joining techniques using gold and nickel gold bumps. Soldering is performed with a thermode and with a laser based system. For these FC joining processes, alternative bump metallurgies based on electroplated gold, electroplated gold-tin, mechanical gold and electroless nickel-gold bumps are applied.
  • Publication
    Low cost flip chip bonding on FR-4 boards
    ( 1995)
    Klöser, J.
    ;
    Zakel, E.
    ;
    Reichl, H.
    Flip-chip technology used directly on printed wiring boards offers minimisation of geometric parameters on conventional low-cost substrates as well as reduction in interconnect distances and inductances, particularly in high frequency applications. This paper describes the investigations of alternative low-cost flip-chip mounting processes using Au and Ni-Au bumps on organic laminate substrates (FR-4). The wiring planes of the PWBs are made by copper plating. The contact pads are topped with an electroplated Sn/Pb-63/37 eutectic solder. Flip-chip mounting was performed with and without flux application. The fatigue life of solder joints, which is limited by the thermal expansion mismatch between chip and substrate, could be significantly increased by a compatible flip-chip encapsulation process. First reliability results of metallurgical analysis and mechanical and electrical behaviour of the different flip-chip joints after thermal cycling between -55 degrees C and +125 degrees C are presented.