5DX Implementation on the Production Floor
Setup isn’t easy, but the tester is only as valuable as its implementation is correct.
Any test or inspection tool is only as good as its implementation on the production floor. Without a carefully planned implementation and continuous monitoring of the implementation, the customer will not realize 1) increased ICT and/or functional test yields and 2) an overall cost savings associated with defects being detected and repaired early on in the production process.
Some – emphasis on some – of the key components to proper system implementation include the following:
Programmer training. The biggest factor in ensuring optimum performance of the test/inspection tool is ensuring a good program is generated. This starts with ensuring that your programmer gets the required training and hands-on experience with the equipment. Training may seem like a non-value added task, but doing this ensures you get the highest value out of your equipment. If an experienced user, there are training programs in which the programmer skill level is audited to identify areas of weakness in program development. Custom classes are then created that focus on the developer’s weaknesses so as to improve program quality moving forward.
Program auditing. To ensure programs are of high quality, ideally they will be audited. Audits are not necessary on all test programs, but can be done periodically to ensure the highest quality, while providing ongoing training for the programmer. Third-party providers or internal audits can be used.
Repair operators training. Repair operators are a vital part of the implementation. A company can use a highly skilled 5DX programmer; however, unless the repair operator is trained to properly disposition those solder joints the tester has indicated as either true or false calls, the tester will not drive improvement in assembly quality. It is important operators are trained in image interpretation, and this training is continued as new package types (such as QFNs or stacked BGAs) are introduced.
Monitor false call rate. Post-repair results from the repair station can be used to determine the source of high false calls. Too many false calls results in repair operators ignoring or missing real defects. For this reason, good test inspection tool implementation will include review and correction of false calls. This starts with a review of false call rates of the different boards, prioritization of the boards, and then analysis of the Pareto of false calls. Monitoring and improving the board program by false call analysis will ensure the most value from the test machine, and will minimize the chance that real defects get to customers.
Feedback loops. This is one of the most important aspects of the tester implementation, yet it often gets ignored. Test results from equipment such as the 5DX can be used to provide feedback to engineers on design and process improvements. For example, during the first prototypes run, a review of solder joint images can identify process problems, and can also dramatically speed the launch of a new product. In addition, feedback from downstream test/inspection equipment, such as ICT/FT, can be used to prevent future solder-related escapes from making it to the end-user or consumer by alerting the 5DX engineer of program weaknesses (e.g., solder escapes found at ICT/FCT that were not detected by the 5DX). Thus, defect integration and analysis should be used to improve the overall manufacturing process, as well as the test programs. It is critical there is continuous communication between the various manufacturing groups.
System maintenance. All test/inspection tools require ongoing maintenance to ensure proper performance. For the 5DX, this translates into performing weekly photometric, bimonthly confirmation & adjustments (C&A), and semiannual preventative maintenance. In addition, the 5DX requires a tight maintenance schedule. If this is not done, the machine’s thickness tables will likely drift, creating a need to update and revise all programs developed during this “drift” period. For test/inspection tools, it is also advised that each company maintain a golden board to be tested before and after C&As and PMs. Verifying the same number of defects provides a simple way to check that the system is working properly, and that maintenance procedures were properly performed.
Training, program auditing, maintenance and feedback loops are all very important to ensure maximum value from the test/inspection tool. Other areas also must be addressed to ensure a proper implementation specific to a given situation. A checklist should be developed that identifies the critical components of the test/inspection tool, along with a plan of how/when they will be monitored.
Barbara Koczera is a former Agilent engineer and founder of Koczera Consulting, LLC (koczeraconsulting.com); barb@koczeraconsulting.com.
