Viewpoint News, August 2009

Believe it or Not...Product Test is Beneficial

by James Campbell - jac@viewpointusa.com

A common thread we at Viewpoint have seen over the years is the belief that product test is a cost burden on the company. I personally have heard from many people who are quick to point out that, if everyone upstream from the test system did their job right, products would just work and test would not be needed.

This philosophy is embedded in the thinking of Six Sigma: reduce variations to zero, so no faults occur. However, in the real world producing faultless product is rarely a reality and perfecting production methods and component suppliers would be ultimately MUCH more costly than spending for a product test system to detect bad product. It is our job as test engineers to help find the balance between producing faultless product and justifying end-of-line test systems. What should we consider to reach this goal?

Background

First, a quick definition for product test. A typical product test achieves the following broad outcomes:

• Controls and measures the UUT (Unit Under Test).

• Makes decisions about the performance of the UUT.

• Analyzes, archives, and reports results.

• Automates for repeatability and efficiency.

These broad capabilities are used in many areas in most organizations, such as:

• Proof of concept

• Design qualification

• Reliability growth

• HALT/HASS

• End-of-line testing

These can be summarized into the 3 main categories of product design, reliability, and manufacturing.

Examples of Paybacks

Capturing ROI of performing tests is often challenging and a difficult process. Luckily for us National Instruments (NI) has spearheaded this effort through interviews with some of their customers. NI has provided solid numbers and proven benefit to implementing end of line test. Figure 1 are all numbers compiled from implementing manufacturing test and the resulting ROI.

Figure 1. NI Compiled Examples of ROI for End of Line Test

These results are simply amazing. They validate the numbers we have seen at similar companies we have worked with over the years, (although because of NDA’s we are unable to make those numbers public). Although implementing a modern end of line test system incurs an initial cost, these ROI numbers make me smile since we can show that test does add value to a company’s bottom line.

But Wait – There’s More!

Figure 1 doesn’t even consider the leverage that these manufacturing test systems can give to the design teams, the quality department, the Lean team, and so on. It also doesn’t include the benefits and leverage of a product design or reliability test system being moved into production as a means of utilizing previously developed test code when building a manufacturing test system.