Giovanni Frezza

Comprehensive design analysis of QFN and PowerQFN packages for enhanced board level solder joint reliability

Board level solder joint reliability is a critical issue for Quad Flat Non-lead Package (QFN), a type of leadframe CSP, during the thermal cycling test. However, currently there are very few papers available on fatigue modeling and thermal cycling test of QFN on board. In this paper, a parametric 3D FEA sliced model is built for QFN (4/spl times/4, 5/spl times/5, 6/spl times/6, 7/spl times/7, and 8/spl times/8) and PowerQFN-8/spl times/8 on board with considerations of detailed pad design, realistic shape of solder joint and solder fillet, and non-linear material properties. It has the capability to predict the fatigue life of solder joint during the thermal cycling test. The fatigue model applied is based on Darveauxs approach with non-linear viscoplastic analysis of solder joints. The solder joint damage model is used to establish a connection between the strain energy density (SED) per cycle obtained from the FEA model and the actual characteristic life during the thermal cycling test. Higher SED leads to shorter fatigue life. For the test vehicles studied, the maximum SED is observed mostly at the top corner of peripheral solder joint.

DESIGN FOR BOARD LEVEL RELIABILITY OF A MINIATURIZED MEMS PACKAGE: STACKED DIE TQFN

A new type of MEMS 3D package is introduced: stacked die Thick Quad Flat Non-lead (TQFN), for application as a multiple axis linear accelerometer. Both solder joint and die reliability during board level thermal cycling test are important concerns, as they affect the functionality and quality of the product. Design analyses are performed to study the effects of 12 key design variations in package dimensions and material properties, on solder joint reliability.

Packaging for a rotational accelerometer: Is a standard plastic SOIC an industrial solution?

On the contrary of microelectronics where standard packages like e.g. DIP, QFP, BGA, SOIC dominate, microsensor packaging seems to be characterized by custom and application-specific packages. Moreover, in microsensor applications packaging is typically a relevant cost component of the whole system. In this scenario, the main question to solve for a high volume and no product specific company mission is the following: how to design versatile, reliable, low-cost packages for microsensor. In this article the assembly solutions for a low-cost mass production of a rotational accelerometer sensor are shown. From the packaging design point of view, the stress minimization has been the main guideline for any assembly process and material characterization choice. The process and material issues, including numerical simulations, optimization by design and experiment, are discussed in detail. Breakthrough in this project were the wafer to wafer bonding as well as the die singulation, the die to die interconnection and the thermomechanical stress minimization.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.