Material Selection
DEFINITION
The process of matching component quality and reliability with intended use and environment to reduce opportunity for product failure.
SITUATION
Technologies continue to evolve, improve and provide more options to design teams. Some of these changes optimize cost, performance or quality to meet specific needs in the market. Design teams need to select materials to meet many competing requirements; reliability is often a difficult criterion to judge. The material performance may be dependant on the design, interactions with other nearby materials or manufacturing processes, or the intended use environment. Vendors are often unable to fully judge the suitability of materials in a specific situation.
OBJECTIVES
To select product elements that will meet or exceed reliability objectives at the lowest possible total cost.
VALUE TO YOUR ORGANIZATION
Selecting materials that meet performance and reliability objectives reduces redesigns, focuses time sensitive reliability testing in areas of highest risk and focuses testing on specific material properties. Also, selecting the right materials may reduce the product performance variation, improve production yield, and reduce overall product costs.
RELIABILITY INTEGRATION
An example of Reliability Integration during Material Selection is as follows:
Using FMEA and HALT to Help Select Materials
Based on desired goals and expected usage & environment, the team can build a robust design that will perform as predicted. Use FMEA and HALT to focus on high risk areas and provide input to cost reduction or reliability improvement opportunities.
METHODOLOGY
Starting with a combination of discussions and component reviews, we focus on material properties and common failure mechanisms. We then incorporate other tools as needed to provide details to the analysis; these may include stress/strength analysis, derating, and FMEA, resulting in a set of recommendations to select materials. In some cases, we recommend further characterization before making a selection.
CASE STUDIES/OPTIONS
The following case studies and options provide example approaches. We shall tailor our approach to meet your specific situation.
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New Technology Materials
A computer design team learns of the benefits of organic tantalum capacitors and expected to use them on an upcoming project. The project manager had a few concerns and wanted to better understand the reliability risks and other potential downside issues that may occur. We researched current literature and helped the team develop a derating experiment resulting in a set of design guidelines and product testing criteria.
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Material Wear-out Properties
A high risk element of an Automotive Cabin application was the cooling of the analog ASIC. The selection of the fan that would meet the reliability objectives became a critical decision. The vendor datasheets for viable fan solutions did not provide adequate reliability information to make a decision. We researched the wear-out characteristics of the bearings, developed a model for the dominant failure mechanism, and helped them conduct a comparative accelerated life test. The customer used the results to select the best fan and deploy the product.
