Machine capability analysis: using a mobile metrology system to tweak machine performance can reduce defects and improve productivity.[TEXT NOT REPRODUCIBLE IN ASCII ASCII or American Standard Code for Information Interchange, a set of codes used to represent letters, numbers, a few symbols, and control characters. Originally designed for teletype operations, it has found wide application in computers. ] Problem: Placing components such as 0201s, 0.4 mm fine pitch and flip chips A chip packaging technique in which the active area of the chip is "flipped over" facing downward. Instead of facing up and bonded to the package leads with wires from the outside edges of the chip, any surface area of the flip chip can be used for interconnection, which is typically done in increasingly smaller package sizes requires tighter placement accuracy specifications in the surface-mount assembly process. Added to the drive for reducing defects, increasing throughput and improving productivity and efficiency rates were cause for a major automotive electronics producer to reevaluate equipment performance and processes. A preliminary study of over 110 assembly process machines revealed that placement accuracy defects were at an unacceptable level. Additionally, when programs were transferred between production lines, it took over six hours to manipulate the pattern programs to adjust the equipment's placement accuracy to the product. The process was time consuming and contrary to equipment productivity requirements, and the human error was contributing to the defect rate. Problem Solved: Our studies revealed inconsistencies in placement accuracy from machine to machine. The company considered dedicating certain products to specific production lines. The idea was ruled out because it would restrict flexibility to react to fluctuating fluc·tu·ate v. fluc·tu·at·ed, fluc·tu·at·ing, fluc·tu·ates v.intr. 1. To vary irregularly. See Synonyms at swing. 2. To rise and fall in or as if in waves; undulate. v. production volumes over multiple products and cause scheduling conflicts that could potentially add process inefficiencies. The solution was to focus on operating the equipment within the capabilities of their placement accuracy specifications. However, the metrology tools and resources required for the job were not available internally, were too costly to acquire and would have caused unacceptable delays in launching a defect reduction program. Since the project mandated The Project Mandate is a general outline of a business project proposal. It includes or points to the projects's business case, or Charter, the High and Low Level Requirements, Risks, Costs, Benefits and any other documentation. the expertise of an external source experienced in characterizing placement equipment accuracy, a company with mobile metrology services and software to analyze placement accuracy capability was brought in. Characterizing Capability The equipment used for the analysis was developed specifically to measure x, y and theta Theta A measure of the rate of decline in the value of an option due to the passage of time. Theta can also be referred to as the time decay on the value of an option. If everything is held constant, then the option will lose value as time moves closer to the maturity of the option. positioning for each placement spindle spindle: see spinning. A rotating shaft in a disk drive. In a fixed disk, the platters are attached to the spindle. In a removable disk, the spindle remains in the drive. Laptops use spindle designations to indicate the number of built-in drives. . It generates a statistical report to characterize placement capability. The process uses a portable vision coordinate measuring machine (CMM (Capability Maturity Model) A process developed by SEI in 1986 to help improve, over time, the application of an organization's supporting software technologies. ) that measures placement accuracy of components against expected placement positions. Highly accurate replica Earlier document exchange software from Farallon Communications, Inc. that converted a Windows or Mac document into a proprietary viewing format. The viewer could be distributed separately or embedded within the document itself, turning it into a single-document viewer. components and glass plates remove variability caused by materials other than the placement machine. By characterizing placement capability, we can zero in on the mechanical attributes that can cause shifts in placement accuracy and affect repeatability. Once analyzed an·a·lyze tr.v. an·a·lyzed, an·a·lyz·ing, an·a·lyz·es 1. To examine methodically by separating into parts and studying their interrelations. 2. Chemistry To make a chemical analysis of. 3. , specific features can be defined and corrective actions--such as replacing worn parts, making adjustment or trimming the machine with the appropriate offsets--can be accomplished easily. Positive Results The immediate impacts of the analysis and corrective actions A corrective action is a change implemented to address a weakness identified in a management system. Normally corrective actions are instigated in response to a customer complaint, abnormal levels if internal nonconformity, nonconformities identified during an internal audit or were an 80% reduction in placement defects and an average increase in intrinsic availability of over 10%. Also, readjusting pattern programs when products were moved between lines was no longer necesary. The programs can be generated from CAD files to maintain quality standards so operators and technicians do not have to modify the x, y or theta locations. As a result, products can be moved from line to line in two hours, instead of six, and the human-induced error of adjusting programs by eye was eliminated. Machine capability analysis is more than a tool or a method. It is a way of defining and implementing continuous improvement in the manufacturing environment. By characterizing machine placement performance, we can target specific corrective actions to decrease defects and increase machine efficiency and overall productivity. [FIGURE 1 OMITTED] Peter Bollinger (bollinger@uic.com) is director of GSM (Global System for Mobile Communications) A digital cellular phone technology based on TDMA that is the predominant system in Europe, but also used worldwide. Developed in the 1980s, GSM was first deployed in seven European countries in 1992. platform products with Universal Instruments Corp., Binghamton, NY. [ILLUSTRATION OMITTED] |
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