Technical Library | 1999-05-09 13:07:16.0
This paper will give the reader a general understanding of EOS and ESD phenomena. It specifically addresses hand soldering's role in EOS and ESD and how to protect against and test for potential problems. It discusses how Metcal Systems address EOS and ESD concerns and how they differ from conventional soldering systems.
Technical Library | 2019-06-17 15:09:43.0
Very often pick and place machines are programmed using CAD data. This data increases the accuracy, precision, and repeatability of its component placement objectives. CAD data makes fine pitch and small component assemblies repeatable, but cannot adjust to a particular board unless it is exactly the same size and shape of the original board used for programming. The process by which printed circuit boards (PCBs) are made only allows some minor changes inboard size and shape, but these small differences are enough for parts to be misplaced. For this reason we use fiducial marks to increase the chances of precise component alignment.
Technical Library | 2011-02-24 19:20:14.0
In the selective soldering process, dross can be detrimental. Dross (and I use this term to encompass all surface contamination) is created in conjunction with the presence of Oxygen in two different areas of the process, and by separate means. Each must
Technical Library | 2018-11-06 12:42:25.0
Solder paste is a homogeneous, stable suspension of solder powder particles suspended in a flux binder, and is one of the most important process materials today in surface mount technology (SMT). By varying the solder particle size, distribution and shape, as well as the other constituent materials, the rheology and printing performance of solder pastes can be controlled. Paste flow behavior is very important in defining the printing performance of any paste.The purpose of this paper is to study the rheological behavior of SAC (Sn-Ag-Cu) solder paste used for surface mount applications in the electronic industry. The reason why the rheological tests are presented in this paper are two critical sub-processes: aperture filling and paste withdraw. In this paper, we report on the investigation of the rheological profiles, the serrated cone-to-plate system was found as effective in parameter minimizing the wall-slip effect
Technical Library | 1999-04-26 11:52:34.0
An evaluation of two fluxers, one with a reciprocating ultrasonic head and the other with microjets, was performed using nine independent criteria. The paper describes the methods of testing and the results.
Technical Library | 2010-10-13 17:29:21.0
The number of failures caused by electrostatic discharges (ESD) has been increasing for some time now. So, it is necessary for everyone, who handles electrostatic sensitive devices (ESDS), to know the reasons of such failures. This presentation will give
Technical Library | 2015-08-13 15:52:40.0
Pad cratering has become more prevalent with the switch to lead free solders and lead free compatible laminates. This mainly is due to the use of higher reflow temperature, stiffer Pb-free solder alloys, and the more brittle Pb-free compatible laminates. However, pad cratering is difficult to detect by monitoring electric resistance since pad cratering initiates before an electrical failure occurs. Several methods have been developed to evaluate laminate materials' resistance to pad cratering. Pad-solder level tests include ball shear, ball pull and pin pull. The detailed methods for ball shear, ball pull, and pin pull testing are documented in an industry standard IPC-9708. Bansal, et al. proposed to use acoustic emission (AE) sensors to detect pad cratering during four-point bend test. Currently there is an industry-working group working on test guidelines for acoustic emission measurement during mechanical testing.
Technical Library | 2019-03-13 15:19:55.0
It is well documented that Nano coatings on SMT stencils offer many benefits to those assembling PWBs. With reduced standard deviation and improved transfer efficiency nano coatings can provide, there is also a cost. As PWB assemblers work to justify the return on investment, one key question continues to arise. What is the durability or life of these coatings and what can be done in the print process to maximize the life of the coatings?This paper addresses durability of the coatings in relation to the number of print cycles and underside wipe cycles applied as well as materials used on the underside wipe process. Different parameters will be applied and data will be collected. The results of this study will be summarized to help those using or considering the use of these nano coatings to improve their print process and suggestions will be given to maximize the life of the coatings.
Technical Library | 2020-08-27 01:15:10.0
Automobile surface defects like scratches or dents occur during the process of manufacturing and cross-border transportation. This will affect consumers' first impression and the service life of the car itself. In most worldwide automobile industries, the inspection process is mainly performed by human vision, which is unstable and insufficient. The combination of artificial intelligence and the automobile industry shows promise nowadays. However, it is a challenge to inspect such defects in a computer system because of imbalanced illumination, specular highlight reflection, various reflection modes and limited defect features. This paper presents the design and implementation of a novel automatic inspection system (AIS) for automobile surface defects which are the located in or close to style lines, edges and handles. The system consists of image acquisition and image processing devices, operating in a closed environment and noncontact way with four LED light sources. Specifically, we use five plane-array Charge Coupled Device (CCD) cameras to collect images of the five sides of the automobile synchronously. Then the AIS extracts candidate defect regions from the vehicle body image by a multi-scale Hessian matrix fusion method. Finally, candidate defect regions are classified into pseudo-defects, dents and scratches by feature extraction (shape, size, statistics and divergence features) and a support vector machine algorithm. Experimental results demonstrate that automatic inspection system can effectively reduce false detection of pseudo-defects produced by image noise and achieve accuracies of 95.6% in dent defects and 97.1% in scratch defects, which is suitable for customs inspection of imported vehicles.