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The wafer backside grinding process has been a crucial technology to realize multi-layer stacking and chip performance improvement in the three dimension integrated circuits (3D IC) manufacturing. The total thickness variation (TTV) control is the bottleneck in the advanced process. However, the quantitative analysis theory model and adjustment strategy for TTV control are not currently available. This paper developed a comprehensive simulation model based on the optimized grinding tool configuration, and several typical TTV shapes were obtained. The relationship between the TTV feature components and the spindle posture was established. The linear superposition effect of TTV feature components and a new formation mechanism of TTV shape were revealed. It illustrated that the couple variation between the two TTV feature components could not be eliminated completely. To achieve the desired wafer thickness uniformity through a concise spindle posture adjustment operation, an effective strategy for TTV control was proposed. The experiments on TTV optimization were carried out, through which the developed model and TTV control strategy were verified to play a significant role in wafer thickness uniformity improvement. This work revealed a new insight into the fine control method to the TTV optimization, and provided a guidance for high-end grinding tool and advanced thinning process development. [ABSTRACT FROM AUTHOR]

To date, the most common method for setting the magic angle in magic angle spinning (MAS) solid state NMR experiments has been to monitor the NMR signal from a quadrupolar nuclide (such as 79Br in KBr) under MAS, then swapping to a sample of interest. Here we introduce the use of single crystal sapphire rotors as a new method to set the magic angle while spinning a sample of interest. Using both simulations and experiment, we show that the 27Al satellite transitions for a single crystal sapphire rotor spinning about its crystalline c-axis manifest off magic angle as five resonances that coalesce into three peaks with maximum intensity at the magic angle. The difference in frequency between the satellite transitions can be used to measure the offset from the magic angle with high precision.

Precise alignment of the sample's spinning axis is vital for many magic angle spinning solid state NMR experiments. Spherical rotors are a new paradigm for magic angle spinning NMR, having been demonstrated to spin stably with little risk of rotor crash, but like cylindrical rotors, they have previously only utilized a mechanical adjustment method to set the sample's rotation axis to the magic angle. Here we show that by using a second gas aperture within the stator, a spherical rotor's axis of rotation may be precisely pitched about the magic angle without mechanical adjustment or motion of the stator. The 2H MAS sideband lineshape of the carboxylic acid deuteron resonance in d4-malonic acid is used as a measure of the rotor's absolute deviation above or below the magic angle by comparing the experimental data to simulated lineshapes. We observe a linear, monotonic relationship between the angle adjustment gas flow rate and the rotor's pitch angle, which is also accompanied by an increase in spinning rate. Precise and in operando control of the spinning axis angle is expected to have considerable advantages to future implementation of MAS within narrow-bore magnets, and for variable angle spinning (VAS) and dynamic angle spinning (DAS) experiments.

A trapezoid-type stick–slip piezoelectric linear actuator using a right circular flexure hinge mechanism was proposed, designed, fabricated, and tested with the aim of accomplishing linear driving based on stick–slip motion. The angle adjustment of the trapezoid beam was used for generating lateral motion on the driving foot of the flexure hinge mechanism. A method of tuning the lateral motion of the flexure hinge mechanism was discussed. Based on the finite-element method, a proper angle of the trapezoid beam was obtained. The analysis results proved that asymmetrical flexure hinge mechanism can increase static friction force in slow extension stage and decrease kinetic friction force in quick contraction stage by lateral motion of the driving foot. A prototype was fabricated and its experimental system was established. The mechanical output experiments showed that the prototype achieved maximum output velocity and load of 5.96 mm/s and 3 N at a voltage of 100 V$p-p$ and a frequency of 500 Hz, respectively. [ABSTRACT FROM PUBLISHER]

The aim of this article is to analyse the involute gear of a ship´s gear pump. The gear applied in a direct gear is usually designed to comply with requirements for sustainability, reliability and operability under unfavourable working conditions. These requirements can be achieved by adjusting the axis distance, angular correction, as well as by rearranging the pressure angle. These modifications are directly interconnected. [ABSTRACT FROM AUTHOR]

Abstract: 2-Photon laser scanning microscopy (TPLSM) is often used for chronic in vivo studies. Small deviations in the sample orientation, however, make comparison of three-dimensional image stacks taken at different time-points challenging. When analysing changes of three-dimensional structures over time (4D imaging) this fundamental problem is one of the main limitations when complex structures are studied repetitively. We used an upright two-photon microscope complemented with a software-controlled stage-rotation instead of a conventional stage for chronic in vivo imaging in the brain of transgenic mouse models of Alzheimer''s disease. Before every session an optimal imaging condition was successfully created by aligning the surface of the cranial window perfectly perpendicular to the laser beam. Deviations in the sample orientation between consecutive imaging sessions could be eliminated which improves conditions for chronic in vivo studies. [Copyright &y& Elsevier]

Abstract: A mathematical model of transmission performance of 2K–H pin-cycloid planetary mechanism with one tooth difference is proposed based on static analysis of actual meshing transmission process between gear pairs considering friction. Computer program for the output moment calculation is developed and is used to analyze the effects of the kinematics parameters on the transmission performance. With the theoretical guidance, the self-locking performance of the seat angle adjustment mechanism of an automobile is improved. The presented mathematical model also provides a basis for further investigations such as the effects of tooth profile and machining error on the transmission performance. [Copyright &y& Elsevier]