08 Mar 2007
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Bulk acoustic wave delay lines
Product and Process Improvement
Requirement
Our customer was producing a solid-state acoustic wave signal-processing device for a major military aircraft program. They wanted to improve the production process in order to reduce the unit cost by 22% per device over 540 devices, taking into account the investment costs of the proposed process improvements.
Solution
In order to achieve the required 22% saving on the Unit Production Cost, the required cost saving would only be possible through a combination of yield improvement and process efficiency improvement. In order to review the opportunities for such improvements, the following activities were undertaken:
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Improvement in the manufacturing process
Product Assurance Group developed a production tracking procedure to collect quality performance metrics for each production stage. Each unit was tracked through the manufacturing process, and the time and amount of rework required were collected. From this data, the stages producing a poor yield were identified.
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Improvement in Yield Performance
Product Assurance Group investigated the root causes of poor manufacturing yield. In most cases, the issues were associated with a complex process, for which the effect of the process parameter settings were not fully understood. Experiments were proposed to determine the optimal settings for these parameters. A cost benefit analysis was also conducted to prioritise the proposed actions, in order to identify the best Return On Investment for both cost and schedule.
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Adherence to Delivery Schedule
Problems in the manufacturing and assembling process would have an impact on the delivery schedule if there were not enough finished units available. Product Assurance Group used a simulation tool that indicated the number of units needed in stock in order to protect the delivery schedule.
Benefits
Following the work of Product Assurance Group, the First Time Yield of a solid-state acoustic wave signal-processing device was increased by 27%, whilst there was a 17% reduction in the manufacturing throughput time and the cost of holding inventory. Product Assurance Group’s approach was well received by the customer, who subsequently reported good stock control and delivery schedule adherence. The waste due to rework and scrap was reduced to a level that the customer decided not worthy of further investment. The process improvements proposed enabled the customer to achieve their required unit cost reduction.
