The advances in miniaturisation and ever increasing complexity of integrated circuits
frequently mean an increase in the number of connections to a component with simultaneous reduction
in pitch. For these emerging smaller contact geometries, micro‐laser connection technologies are
required. The reliability of the connection plays a decisive rôle. The
implementation and reproducibility of laser connections technology in micro‐electronics depend on
good thermal contact between the two parts and high quality absorption of the material surface used. Laser energy can cause local melting due to overheating of the lead because
of the low distance between lead and bump. This effect influences the reproducibility of the contacts.
Even the slightest interruption in the thermal contact of the parts can
cause non‐reproducibility of the contacts. Materials with a higher quality of absorption, for example
Sn(32% ), can be soldered with a good level of reproducibility. This clearly differs from gold (4% ) or
copper(7% ) surfaces. Due to the low absorption of these materials it is necessary to use a laser
with a higher intensity to produce the same energy. Irregularities in the quality of absorption, laser
instability and thermal contact can not guarantee reproducibility of the interconnections with this high
laser intensity. The FPC (fibre push connection) system offers several
solutions to the problems mentioned. This system enables the laser to be transported by fibre to the
contact parts. The end piece of the fibre serves at the same time as a pushing unit. The advantage of this system is that the attenuation heat of the fibre end surface is also
available for the connection. This improves the use of laser energy. As part of the laser energy at the
end surface of the fibre is transformed into thermal energy, independently of the absorption quality of
the material used, connection of a gold‐plated contact part is possible. By pressing the connecting parts
with the tip of the fibre, optimal coupling is achieved. The reproducibility of different metallisations and the reliability of connections with a pitch
below 100 μm are presented as well as further applications of this system.