SMT assembly process of several commonly used inspection methods
Operator fatigue is why the 100% inspection of a manufacturing defect is often unable to find the reasons for each of the other, this is a high cost, worthless value-added operations. It rarely achieve higher product quality and customer satisfaction desired goal. A few years ago, we began to use "process monitoring" the term, not the censor, because we want to produce ideas workplace change from a reactive to proactive prevention. An inspector usually sit at the end of the assembly line, inspection products. In an ideal case, the process monitoring activities, product inspection and monitoring of the process is a balance between - for example, verify that the correct process parameters are used to measure the performance of the machine, and the establishment and analysis of control chart. Monitoring of the process assumes a leadership role in these activities; they help the machine operator to complete these tasks. Training is a key factor. Process monitors and machine operators must understand the process standards (for example, IPC-A-610), process monitoring concepts and related tools (eg, control charts, Pareto diagrams, etc.). Process monitors can improve product quality and process monitoring. For manufacturing a key team member monitors a defect prevention approach to encourage, rather than a way to find and repair. Excessive checking is also a widespread problem. In many cases, over-inspection is due to the IPC-A-610 process standards caused by the dislocation of understanding. For example, insert the installation of components, many on both sides of the censor board would also like a perfect circle of welding foot hole completely filled. However, this is not the IPC-A-610 required. Check the quality inspector's attention as the degree of tension and concentration fluctuations. For example, the fear of (the management of pressure) may increase the degree of attention on production sites, the quality may improve over time.
However, if a large number of checks is the main way to check, then the defective product may have, and may be out of the factory. Another term that we should avoid is the welding (touch-up). In being an industry, many employees think that welding is a normal and acceptable part of the assembly process. It is very unfortunate, because any form of rework and repair should be seen as undesirable. Rework is often seen as undesirable, but it is instilled in the necessary information throughout the manufacturing organization. Important to establish a defect and rework as to avoid and most do not want the manufacturing environment. For most companies, manual inspection is the first line of defense. Inspectors use a variety of zoom tools, more recently, to view components and welding points. IPC-A-610 check the component pad width based on the establishment of the amplification some basic guidelines. The main reason for these guidelines is to avoid over-amplification caused by the excessive checks. For example, if the pad width is 0.25 ~ 0.50 mm, then the desired magnification is 10X, 20X, if necessary can also be used for reference.
Each inspector has a favorite checker; there is a mechanic with three folding pocket magnifying glass lens is better. It can carry a maximum magnification of 12X, which is just suitable for fine pitch solder joints. Perhaps, the most common diagnostic tool is the microscope, magnification range of 10-40X. But the fatigue caused by continuous use of microscopes, often lead to excessive checking, because the magnification is usually more than IPC-A-610 guidelines. Of course, need to carefully check for possible defects or useful. For a general examination of choice can be equipped with a zoom lens (4-30X) and high-resolution color video monitor system. These systems are easy to use, more importantly, less prone to fatigue than the microscope. High-quality video systems cost less than $ 2000, a good microscope, also in this price range. The additional benefit of video systems more than one person can see the object, which inspectors need training or a second opinion is helpful. Edmund Scientific Company (edmundscientific.com) amplification of a large number of tools, from hand-held magnifying glass to a microscope to the video system.
To sum up, the establishment of a balance between 0-100% inspection monitoring strategy is a challenge. From this point, the key check point, we will discuss the inspection equipment. ... Automation is wonderful; in many cases, more accurate than the inspectors, fast and efficient. But can be quite expensive, determined by their degree of complexity. Automated inspection equipment may dilute the people's consciousness, give people a false sense of security. Solder paste inspection. Solder paste printing is a complex process, it is easy to deviate from the desired results. Need a clearly defined and appropriate strategy for the implementation of process monitoring to keep the process under control. Manual inspections at least cover the regional and measuring the thickness, but the best use of automated coverage, thickness and volume measurements. Using the range control chart (X-bar R chart) to record the results.