The main aim of this work was to determine the soldering, thermal and mechanical properties of joints fabricated by use of Au-20Sn solder. Soldered joints were fabricated by application of a flux-free process with assistance of power ultrasound. By acting of power ultrasound, the Au-20Sn solder wets the surface of Cu, Ag and Ni substrates. The contact wetting angle on all substrates varied with...

Anisotropic conductive film (ACF) has been used for flip chip interconnection of a silicon based MEMS finger print sensor to a signal processing ASIC. The assembled sensor device was subjected to a short term high temperature profile with peak temperature 260 C simulating subsequent reflow soldering of the device, and to thermal shock cycling from -40 to +85 C. The reliability of interconnect...

This work addresses the issue of attaching the force-centring part (a round ball) to the load cell of a force sensor, a piezoresistive thick-film Wheatstone bridge deposited onto a ceramic cantilever. As the current soldering process requires expensive metallisation steps for both the ball and the cantilever, and subjects the solder pads used for mounting the cantilever to an additional reflow ...

In this paper three-dimensional (3-D) suspended helical nanobelts (HNBs) with ultra-high flexibility are assembled by the external field guidance. Electromagnetic (EM) and electrostatic (ES) force by external potential are characterized quantitatively to guide the assembly of HNBs to create force sensing probe. Both ends of HNBs and target electrodes are attached with ferromagnetic metal connec...

We introduce a strategy for the verification of relational specifications based on the analysis of monotonicity of variables within formulas. By comparing with the Alloy Analyzer, we show that for a relevant class of problems this technique outperforms analysis of the same problems using SAT-solvers, while consuming a fraction of the memory SAT-solvers require.

Alloy is a formal modeling language based on first-order relational logic, with no native support for specifying reactive systems. We propose an extension of Alloy to allow the specification of temporal formulas using LTL, and show how they can be verified by bounded model checking with the Alloy Analyzer.

As a vital component of electronic products, the quality printed circuit board (PCB) assembly directly affects applications and service life. During reflow soldering process, PCB may suffer excessive warpage. Therefore, in order to avoid such failure, this paper conducts finite element simulation temperature change deformation process according theoretical model for heat transfer then explores ...