The Hidden Potential Of Test Engineers

Design engineers are seen as the cornerstone of new projects in many semiconductor companies, working away with the team to design the next product and making sure it meets all specifications.

We pay little thought to the test engineer, who works in the shadows designing algorithms, hardware and software that could pass or fail each die. The test engineer is the last line of defense between potentially defective devices and your customer’s customers, the end-user.

Today, with the help of our resident engineering management expert, Carl Moore—a yield management specialist—we will explain how test engineers impact the bottom line. As a former product and test engineer, Moore believes that test engineers have hidden potential to increase revenue.

“The value of a test engineer often boils down to two factors,” says Moore. “One is the company’s mindset and attitude to test. The most successful companies see the value in including test engineers early in production and throughout the process, while others see it as a necessary evil. The second is the test engineer’s mindset: given the nature of the role, test engineers often underestimate their impact and importance. As they are busy writing code and setting up test codes and algorithms, they sometimes don’t have time to share their insights with their team.”

We will focus on the company’s mindset in this article. So how can a test engineer add value? Two ways — reduce defective devices and provide quality assurance. But if this is all you use your test team for, you could be losing hundreds of thousands of dollars.

The most successful companies include test engineers early in the workflow. If you are managing or overseeing production, you could include the test team in the project kick-off meeting. Encourage test engineers and all members of the team to give insights. They will spot things that others don’t. You will benefit from having different mindsets in the room.

“When I worked in Maxim, the test engineer was a valuable member of the development and manufacturing teams,” Moore says. “The VPs recognized the importance of the test engineers and their inputs innovated new methods for testability and improved profits. Test engineers drove lower cost of test by using production data to find subtle issues and improve the product and systems.”

Give the test team time at the start to evaluate the design and project. This will help your product and design team to edit the design to help testing run smoother and faster. Time to market is key to maximizing profits. If the test development starts at the beginning of the project, then production test will be ready when the die comes out of fab, and quickly ramp. Collaboration between the design and test engineers is key in enabling design for test (DFT).

“I believe that each hour a test engineer spends evaluating early in the development cycle saves the company thousands of dollars,” says Moore. “Suppose the company produces and tests 1 million ICs each week. By reducing the test time of each device by a few milliseconds, this can add up to thousands of dollars each day. The team should always be thinking of the value of every millisecond.”

The business unit could save $500,000 on a single product by reducing test time and improving yield. Commercial ATE testers are very expensive, so every second matters. Companies that value test, and test engineers, tend to perform better and be more successful.

Any impact on test engineering time will ease the company’s financial burden. The test engineer will advise on ways to make the test run smoother. This eases the cost at die level. The company will save time and money. The test engineers will be able to test more in a shorter time frame. This means buying fewer testers or having higher capacity. The product team will benefit from the knowledge that their design had shorter test time and higher yield than previous versions.

In high volume, when a problem arises, the speed of yield analysis and correcting a problem can impact many lots in the pipeline. It is critical to solve these problems quickly so that the flow of production keeps moving and the customer does not see any impact.

The test engineers will spot anomalies during test that the product and design team may not have access to. They will share it with the team to help them in the next project. In this way, test engineers actually help improve yield over time.

With a yield management system (YMS) the savings can be even greater. You can leverage reports and test programs from previous projects. Reuse is important in design, and also for test hardware/software. Yield management can even improve design by highlighting performance issues on circuit blocks and allowing optimal reuse.

A good YMS also can make subtle issues stand out visually and display in simple charts so that all the members of the team, as well as management, can see quickly what might be trending with the product and correct it.