Speaker
Dr
Markku Oinonen
(Helsinki Institute of Physics)
Description
The silicon strip detector (SSD) modules cover the two outermost layers of the Inner
Tracking System of ALICE. The SSD module assembly will be performed at three
locations in Europe: Helsinki, Strasbourg and Trieste. After a tedious preparation
period within the whole ALICE SSD collaboration, mass production of the SSD modules
was launched during autumn 2004 in Helsinki. Presently all the sites are producing
the SSD modules successfully.
Due to tight requirements of light structure and flexible geometry the so-called
single-point tape-automated bonding (spTAB) with thin polyimide-Al cables has been
chosen as interconnection technique. The technique is based on Ukrainian industrial
technology. In an spTAB interconnection very reliable Al-Al bonds connect the front-
end chips, hybrids and sensors together. The use of Al as conductor allows for low-
force ultrasonic bonds to be performed gently at room temperature.
Presently, the spTAB interconnections are performed successfully at all three sites
with bonding yield approaching close to 100%. This paper describes the phases in
bond process tuning before achieving this result, including discussion on the most
probable root-causes of failures and the long-term reliability of the
interconnections. The interconnection reliability defines the lifetime of an SSD
module as a significant part of the assembly.
Author
Dr
Markku Oinonen
(Helsinki Institute of Physics)
Co-author
ALICE SSD collaboration
(Helsinki - Kharkov - Kiev - Strasbourg - Trieste - Utrecht)
