Shear stress modelling utilized to assess reliability

Polymeric interconnections are used in various applications and may consequently be exposed to a wide range of different environments during their life-time. Accelerated life tests are typically used to examine their reliability in different environments. However, the tests are fairly time consuming and often expensive.

“If modelling could be utilised to assess reliability, time and cost savings could be achieved as the need for actual testing would decrease,” says Saarinen.

The results demonstrated that if the failure mechanism of polymeric interconnections is related to shear stress, shear stress modelling can be utilised while conducting reliability studies in thermal environments. On the other hand, if the failure mechanism of the polymeric interconnection is related to thermal expansion of the adhesive matrix, strain modelling which calculates changes in the thickness of an adhesive layer between contacts seems a feasible approach to predicting reliability. 

In addition, Saarinen observed that predicting the reliability of polymeric interconnections is extremely difficult in humid environments due to the numerous factors that can potentially cause failures. It was not possible to use shear stress modelling alone, as the factors causing failure are not only related to shear stress. However, if shear stress modelling is used together with adhesion measurements, it is possible to estimate failure times in a humid environment.

Public defence of a doctoral dissertation on Friday, 24 February

The doctoral dissertation of MSc (Tech) Kirsi Saarinen in the field of electronics “Utilising Shear Stress Modelling in Reliability Studies of Polymeric Interconnections in Electronics” will be publicly examined at the Faculty of Computing and Electrical Engineering of TUT in room TB109 in the Tietotalo building (address: Korkeakoulunkatu 3, Tampere, Finland) on Friday, 24 February 2012 at 12:00.

The opponent will be Adjunct Professor Olli Salmela (Nokia Siemens Networks). Professor Lauri Kettunen from the Department of Electronics will act as Chairman.

Kirsi Saarinen (27) comes from Espoo and works as a researcher at the Department of Electronics of TUT.

Further information:
Kirsi Saarinen, tel. +358 (0) 40 849 0613, kirsi.saarinen@tut.fi

The dissertation is available online at: http://dspace.cc.tut.fi/dpub/handle/123456789/20858?locale-attribute=fi