Compliant Pin Research Articles

Design of a Compliant Robotic End-Effector Tool for Normal Contact Estimation

The use of industrial robots for machining operations such as polishing is gaining popularity these days. However, maintaining constant normal contact on unknown geometrical surfaces still remains a challenge. In order to cope with the issue, this research has developed a unique compliant robotic end-effector that can measure the depth and angles deviation of the robot from the normal complex surfaces in real-time without any prior geometric model of the workpiece. The indigenously developed compliant robotic end-effector is made up of three main components: a novel three-axis force/torque sensor, a compliant contact pin, and a data acquisition (DAQ) board. Initially, the three-axis force/torque sensor has been validated with both simulation and testing. The advantage of being able to take measurements in real-time is provided by the DAQ’s automatic weight compensation feature. Additionally, the pose correction algorithm receives the estimated contact force as feedback during robot surface tracking in order to assess depth and angles and determine the proper distance and perpendicular relationship between the surface and the end-effector. The proposed scheme is then evaluated using a six-axis industrial robot. The experimental results show that the maximum average depth and angle errors are 0.13 mm and 0.64°, respectively. The developed system has achieved significant improvement in contact-based robot surface measuring.

Sliding speed effect in press-fit connection using Finite Element Analysis

Solderless press-fit contacts in power module packages are now gaining more attention in the automotive industry especially in hybrid electric vehicles because of the Restriction of Hazardous Substances (RoHS) directive to eliminate lead-based connections. The production of press-fit assembly is also faster, more convenient, safer, and cheaper than soldered connections. In this paper, the effect of insertion speed of pin to the press-in force as well as the pull-out speed to the retention force was investigated using finite element analysis. An eye-of-the-needle (EON) shape compliant pin with general dimensions was adapted and a transient structural analysis in ANSYS mechanical was used to add and vary the speed of the press-fit pin geometry. Four simulations were conducted with different speeds. The results obtained by FEA show that the speed when kept at constant has no significant effect both on the press-in and retention force. However, when the speed changes due to acceleration, the press-in and pull-out force are both affected.

Toward a Unified Design Approach for Both Compliant Mechanisms and Rigid-Body Mechanisms: Module Optimization

Rigid-body mechanisms (RBMs) and compliant mechanisms (CMs) are traditionally treated in significantly different ways. In this paper, we present a synthesis approach that is appropriate for both RBMs and CMs. In this approach, RBMs and CMs are generalized into modularized mechanisms that consist of five basic modules, including compliant links (CLs), rigid links (RLs), pin joints (PJs), compliant joints (CJs), and rigid joints (RJs). The link modules and joint modules are modeled through beam elements and hinge elements, respectively, in a geometrically nonlinear finite-element solver, and subsequently a beam-hinge ground structure model is proposed. Based on this new model, a link and joint determination approach—module optimization—is developed for the type and dimensional synthesis of both RBMs and CMs. In the module optimization approach, the states (both presence or absence and sizes) of joints and links are all design variables, and one may obtain an RBM, a partially CM, or a fully CM for a given mechanical task. Three design examples of path generators are used to demonstrate the effectiveness of the proposed approach to the type and dimensional synthesis of RBMs and CMs.

Compliant pin chuck for minimizing the effect of backside particles on wafer planarity

A wafer chuck referred to as the compliant pin chuck (CPC) that can minimize the nonplanarity effect of backside particles on semiconductor wafers is presented in this article. The demand for flatter semiconductor substrates has been increasing as the size of the features that can be transferred onto a wafer surface becomes smaller. There are a number of factors affecting wafer planarity, most of which can be corrected by conventional wafer chucks. However, the problem of backside particles (particles affect a large portion of wafer real estate by causing out-of-plane distortion when they get lodged between a wafer and a wafer chuck) has not been adequately addressed by the current wafer chuck technology. The compliant pin chuck was designed to address this concern and fabricated from silicon using lithography based microfabrication techniques. The chuck consists of an array of microflexure mechanisms that react to the presence of backside particles so as to minimize the nonplanarity caused otherwise. It is also shown through experimental results that the fabricated chuck has a planarity of 120nm (standard deviation −3σ) over an area of 30mm×30mm and is less sensitive to backside particles than a conventional wafer chuck.

Compliant pin technology

Problems with traditional soldering methods have led to new methods of providing connections to a backplane. The application of this technology is increasing rapidly in the UK

Design of a Compliant Press-Fit Pin Connection

A design method for a compliant press-fit pin connection in a plated through hole (PTH) is presented. In this connection, both compliant press-fit pin and PTH cause elastic-plastic deformation. Considering this feature, three fundamental design concepts for this connection are discussed. First, three design conditions are set: 1) the upper limit of pin insertion force to protect the copper plate of the inner PTH, 2) the lower limit of pin retention force to accomplish reliable wire wrapping connection, and 3) acceptable PTH diameter tolerance. Second, the deformation and radial force characteristics were studied for both pin and PTH. These characteristics were numerically analyzed by using the elastic-plastic finite element method (FEM). According to actual connection states, the pin edge indentation effect into the plated copper is taken into consideration for the PTH deformation characteristics. Finally, the design point was determined, where the pin and PTH radial forces balance. This design point should satisfy the above-mentioned three conditions. An example of a compliant press-fit pin with N-shaped cross section was studied. Results from the numerical analysis are compared with those obtained from experiments. The two results compare favor- ably.

Compliant Press-Fit Technology Integrated Into a New Back Panel Packaging Approach

Involving, as it does, DIN and Reversed DIN board connectors, compliant press-fit pins, round cable, flat cable, and coaxial-connectors, the Berg Backpanel System has, over the past two years, gained a recognized position in the European and US markets.Development and expansion of the system in depth, and in breadth, is still ongoing. One of the major subjects is press-fit: preloaded press-fit connectors and studies focused on the relationship between printed circuit board properties vs. compliant press-fit pin design.This paper presents results of these developments and discusses design options.

Analysis of an Interference-Fit Pin Connection

Under a simplifying but reasonably justified assumption of noninterference from the adjoining pins, a mathematical analysis of an interference-fit pin connection in a backplane for the initial contact force is presented. Effects of pin shape, stiffness, interference fit, hole shape, and plate material are included in the study. A closed form solution is obtained for estimating the initial contact force in the joint, thus eliminating the need for complicated numerical techniques generally used for such complex problems. Numerical results of initial radial forces for different pin and plate parameters are presented. An example of a lanced compliant pin is discussed.