Off-centered Ball Resolution Through Multi-hole Process Plate Implementation at Wirebond Process

With the continuous trend of new technologies in semiconductor manufacturing assembly, challenges and issues are unavoidable. This paper presents the modification and improvement done on the process plate design to eliminate the bouncing effect of the silicon die that leads to off-centered ball (OCB) reject during the formation of wire on a quad flat no-leads (QFN) device. The panel type single-row process plate cannot totally vacuum the warped leadframe and this is resulting to off-centered ball. Through changing the panel type single-row process plate to panel type multi-hole process will have a strong vacuum sucked underneath the leadframe and eliminates the occurrence of off-centered ball. Future works could use the improved process plate design for devices of similar configuration.

Addressing Off-Centered Ball through Solder Paste Material Evaluation

Stencil printing using solder paste material is one of the challenging processes in semiconductor assembly manufacturing. During evaluation of a semiconductor device, off-centered ball issue was encountered. The study aimed to mitigate the off-centered ball issue at stencil printing process by exploring the effect of different solder paste materials. Both solder paste materials were cured using the same reflow condition. However, solder paste material 1 (S1) resulted to cold solder joints while material 2 (S2) showed cured solder paste characteristic. With S2 material used in stencil printing, the off-centered ball occurrence was eventually eliminated. For future works, the solder paste material and configuration could be used for devices with similar requirement.

Ball Misplace Mitigation through Process Optimization of Advanced Leadframe Package

One of the challenging assembly processes in semiconductor manufacturing industry is stencil printing using solder paste as direct material. With this technology, some issues were encountered during the development phase of an advanced leadframe device and one of which is the solder ball misplace or off-centered ball. This paper, hence, focused on addressing the ball misplace issue at stencil printing process. Comprehensive parameter optimization particularly on the print speed and print force was employed to eliminate or significantly reduce the ball misplace defect at stencil printing process. With this process optimization and improvement, a reduction of around 96 percent ball misplace occurrence was achieved.

RESULTS OF RESEARCH OF COMPRESSED DEFORMED COMPOSITE RODS OF T-SECTION REINFORCED WITH WELDING

The article presents experimentally obtained information about the features of the work of compressed deformed rods, reinforced in two ways by increasing the cross section using welding. In the test, a P-200 press was used, on the plates of which centered ball bearings were att ached. Nine rods of T-section 100 cm long from paired corners L40x4 were tested. Three rods were straight: tested without amplifi cation. Six rods had a common curvature in the plane of the gaskets and were reinforced: three rods with pair of short corners L40x4 (length 60 cm); three rods - paired long corners L40x4 (length 100 cm). Loading was carried out in steps of 200 kg until the loss of non-existent ability. As a result, information was obtained on the signifi cant eff ectiveness of the amplifi cation method with long gain angles.

OPTIMIZATION PROBLEM FOR EXTREMALS OF THE TRACE INEQUALITY IN DOMAINS WITH HOLES

We study the Sobolev trace constant for functions defined in a bounded domain Ω that vanish in the subset A. We find a formula for the first variation of the Sobolev trace with respect to the hole. As a consequence of this formula, we prove that when Ω is a centered ball, the symmetric hole is critical when we consider deformation that preserve volume but is not optimal for some case.

Volume degeneracy of the typical cell and the chord length distribution for Poisson-Voronoi tessellations in high dimensions

This paper is devoted to the study of some asymptotic behaviors of Poisson-Voronoi tessellation in the Euclidean space as the space dimension tends to ∞. We consider a family of homogeneous Poisson-Voronoi tessellations with constant intensity λ in Euclidean spaces of dimensions n = 1, 2, 3, …. First we use the Blaschke-Petkantschin formula to prove that the variance of the volume of the typical cell tends to 0 exponentially in dimension. It is also shown that the volume of intersection of the typical cell with the co-centered ball of volume u converges in distribution to the constant λ−1(1 − e−λu ). Next we consider the linear contact distribution function of the Poisson-Voronoi tessellation and compute the limit when the space dimension goes to ∞. As a by-product, the chord length distribution and the geometric covariogram of the typical cell are obtained in the limit.

Volume degeneracy of the typical cell and the chord length distribution for Poisson-Voronoi tessellations in high dimensions

This paper is devoted to the study of some asymptotic behaviors of Poisson-Voronoi tessellation in the Euclidean space as the space dimension tends to ∞. We consider a family of homogeneous Poisson-Voronoi tessellations with constant intensity λ in Euclidean spaces of dimensions n = 1, 2, 3, …. First we use the Blaschke-Petkantschin formula to prove that the variance of the volume of the typical cell tends to 0 exponentially in dimension. It is also shown that the volume of intersection of the typical cell with the co-centered ball of volume u converges in distribution to the constant λ−1(1 − e−λu). Next we consider the linear contact distribution function of the Poisson-Voronoi tessellation and compute the limit when the space dimension goes to ∞. As a by-product, the chord length distribution and the geometric covariogram of the typical cell are obtained in the limit.

How Position, Velocity, and Temporal Information Combine in the Prospective Control of Catching: Data and Model

The cerebral cortex contains circuitry for continuously computing properties of the environment and one's body, as well as relations among those properties. The success of complex perceptuomotor performances requires integrated, simultaneous use of such relational information. Ball catching is a good example as it involves reaching and grasping of visually pursued objects that move relative to the catcher. Although integrated neural control of catching has received sparse attention in the neuroscience literature, behavioral observations have led to the identification of control principles that may be embodied in the involved neural circuits. Here, we report a catching experiment that refines those principles via a novel manipulation. Visual field motion was used to perturb velocity information about balls traveling on various trajectories relative to a seated catcher, with various initial hand positions. The experiment produced evidence for a continuous, prospective catching strategy, in which hand movements are planned based on gaze-centered ball velocity and ball position information. Such a strategy was implemented in a new neural model, which suggests how position, velocity, and temporal information streams combine to shape catching movements. The model accurately reproduces the main and interaction effects found in the behavioral experiment and provides an interpretation of recently observed target motion-related activity in the motor cortex during interceptive reaching by monkeys. It functionally interprets a broad range of neurobiological and behavioral data, and thus contributes to a unified theory of the neural control of reaching to stationary and moving targets.