Fan, John Y. (1990, ASQC) Motorola Inc., Scottsdale, AZ
The objective of the paper is to briefly outline a methodology that Motorola Government Electronics Group has developed to achieve high quality (6 sigma) with its products. Emphasis (of the paper) is placed on the design and component aspects of a product cycle. Since hardware prototyping is becoming both expensive and time consuming, extensive simulation is used to explore different design configurations and components. A quantitative, statistically meaningful result on the performance characteristics is obtained, and used in design trade-offs.
The approach employed by the software tools is not simply Monte Carlo; rather, it is much more a direct sensitivity approach. The building blocks' contribution to output variance, as well as parameters of a component's contribution to output variance, is well known, if that parameter is critical enough. (Current Gain-Bandwidth f~ of a high frequency transistor, for example). Many times, the sensitivities of the components/modules, whose variations cause the majority of output variations, have to be reduced; in order to make the product producible again and again, with physically different components (of the same pad type) placed in different units; or to make the product resilient or immune to environmental changes. This is accomplished either by using a different pad, or by circuit configuration redesign.
In order to support the analysis effort, a component/module database has been developed by the author in which the critical and major parameters of a component are clearly identified. The average, G, range, Cp, Cp k of these parameters are stored in the database, on a part qualification basis (from a particular supplier), or on a lot-to-lot basis. All GEG designers have on-line access to this database. In the early program stage, this database is used for pad selection; later, the parametric data is employed in analog/digital analysis. This database is IBM mainframe based, and both supplier and incoming QA data are incorporated into it.
The conclusion is: In today's fast design/manufacturing environment, in order to compete in the market place, the simulation approach with necessary pad information, is a viable means of achieving 6 sigma quality.