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72 The PCB Magazine • October 2015 Reducing Cycle Time in Electrical Test In most manufacturing plants the back-end struggles with the additive cycle time violations of all previous processes. Everything is "hot" and cycle time is of the utmost importance. Extreme pressure is put on these late stage processes to make up lost time and attempt to ship the product on- time or as close as possible. Unfortunately, many of these latter processes are the most important. In final inspection and test, all of the prior processes are inspected and validated against the customer requirements and industry specifications. Many tools and disciplines are used to help analyze a process to gauge its effectiveness and identify areas of concern or targets for improve- ment. Some examples are Kaizen and 5 Ys. Ka- oru Ishikawa, a Japanese quality pioneer, intro- duced a highly visual diagram to illustrate cause and effect attributes that result in the undesir- able outcome. It is known as the Fishbone. In general terms, with regard to ET, the basic dia- gram is outlined in Figure 1. Now, using the diagram in Figure 1, we must identify the attributes affecting cycle time in ET. Some immediate items come to mind: • Yield • Production issues • Excessive rework • Misleading or confusing fabrication drawings/requirements • Incorrect ET tooling • Missing information • Machine downtime • Human error • Load balancing Using the above diagram, we can extrapo- late these items into the Fishbone. Figure 2 summarizes our list. From that diagram, we can now see the causes that can affect cycle time in electri- cal test. Let's first look at the cause attributes in manufacturing. As I stated earlier, planning and scheduling are extremely important. We see it is one of the attributes listed. In many cases production planners put a fixed time al- lotment for electrical test. However, this can be a problem. Dependent on whether the job is tested on a flying probe or a grid test machine may influence the time it would take the same TesTing Todd BREAKING THE BOTTLENECK: ELECTRICAL TEST CyCLE TIME REDUCTION Figure 1: ishikawa's Fishbone diagram.