Mechanical fatique and life estimation analysis of printed circuit board components


Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Faculty of Engineering, Department of Mechanical Engineering, Turkey

Approval Date: 2006

Thesis Language: English

Student: Cem Genç

Supervisor: YAVUZ SAMİM ÜNLÜSOY

Abstract:

In this thesis, vibration induced fatigue life analysis of axial leaded Tantalum & Aluminum capacitors, PDIP and SM capacitors mounted on the printed circuit boards are performed. This approach requires the finite element model, material properties and dynamic characteristics of the PCB. The young modulus of the PCB material is obtained from 3 point bending tests, resonance frequencies are obtained from modal tests and transmissibility’s of the PCB are obtained from transmissibility tests which are used as fatigue analysis inputs. Step Stress Tests are performed to obtain failure times of the tested electronic components which are also used as the numerical fatigue analysis inputs. Consecutively, fatigue analysis of a sample PCB used in military systems is aimed since it is important to compare the calculated fatigue damage to estimated life limits in order to determine which component(s), if necessary, must be moved to positions of lower damage . For this purpose, power PCB of the power distribution unit used in Leopard 1 battle tank is examined. Numerical fatigue analysis coupled with accelerated life test whose profile is convenient to military platforms is performed. Furthermore, the effects of “eccobond” and silicone on the fatigue life of the components are also surveyed since these techniques are common in electronic packaging. In addition, mean-time-to-failure values are obtained for the tested components by using Weibull distribution. Finally, sensitivity analysis is performed to indicate the effect of certain parameters on the fatigue life of a sample axial leaded capacitor.