Addressing New Testing & Inspection Challenges


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In an interview with SMT Magazine, NK Chari, marketing director for manufacturing technologies at the Electronic Industrial Solutions Group of Keysight Technologies, talked about the challenges in PCBA testing and inspection, tougher requirements for testing, and the need for functional testing. He also mentioned some best practices to consider to improve the PCBA testing and inspection process.

Stephen Las Marias: What are the greatest challenges that your customers face when it comes to PCB assembly testing and inspection?

NK Chari: Electronics manufacturers continue to face challenges for PCBA test (i.e., they want to test as many components and processes as effectively as possible at the lowest cost). Their challenges are compounded by the type of technologies and products they are working on. For instance, we are seeing more RF integration or high-speed component into products. These are shielded components, thus, making it very difficult to do board-level testing.

Las Marias: Are there new or tougher demands and requirements from your customers for testing? If yes, what are they?

Chari: With the advent of the Internet of Things, these PBCAs have become even smaller, and manufacturing volumes are not necessarily very high. Hence, customers have to optimize their test strategy for a mix of medium volume, high-mix, high-complexity production environment. At the same time, new test access challenges continue to surface, with developments like USB 3.0 and integration of higher-speed signals, so the boards can no longer host test pads. Customers have to think of new methods of testing, such as embedded test.

Las Marias: What technology or market trends are driving these issues?

Chari: Concurrently, increasing labor costs are driving manufacturers to really think about, and start adopting automation for smart factories to be in place so that they can maximize their resource utilization and improve their yields and performance. The drive towards Industry 4.0 will mean looking at integrating the entire manufacturing process, from design for test to automation. With costs going up considerably, we can see the trend of our customers manufacturing closer to their end markets. For instance, Mexico manufacturing for the American markets and Europe for the European markets. These will put new demands and requirements on manufacturers as they will need common global test processes that can be used across different sites worldwide and more automation.

Las Marias: What innovations in test and inspection technologies are happening to help customers address these challenges?

Chari: From a board test stand point, apart from driving automation in board test, Keysight’s new Mini In-Circuit Tester is compacting test capabilities into a compact, powerful form factor, and it can be enabled for parallel testing to offer excellent test coverage and increase throughput for handling smaller boards used in IoT products. We are trying to enable more embedded tests with our boundary scan technologies and are continuing to improve our vector less test performances to help manufacturers detect faults on much smaller devices. We are also working on innovations using XML technology to help our customers connect better as they gear towards Industry 4.0.

These innovations are highly appropriate for various markets, such as the automotive sector, where we see customers testing multiple panels simultaneously, especially for sensor boards. These are small form factor boards similar to IoT boards where you can run multiple parallel tests. Keysight is continuing our investments to push test coverage for new IoT and wireless products such as 5G Analysis Reference Solutions, EXM IoT Reference Solutions.

Another area of Keysight’s focus is modular test technologies, which will help manufacturers standardize their test strategies while providing flexibility of reusable modules instead of expensive customized systems.

Las Marias: With all the common test stations built into a typical SMT line—bareboard testing, solder paste inspection, AOI, X-ray inspection, and ICT/flying probe—why is there still a need for functional testing?

Chari: OEMs and contract manufacturers continue to see the addition of test stations as one way to improve their test coverage. However, we believe new technologies provided by in-circuit test, embedded tests with boundary scan are providing very high value where it’s common to see extremely high functional test yields of over 99 % with the test coverage provided by in-circuit test. This enables customers to reduce the functional test needs, especially at the board level. However, functional test is still needed at the assembled product level because it’s the only way to validate and verify the performance of a finished product in an “in-situ” environment to make sure it still operates as it was designed to when operating alongside other functions in a system. Board level functional test is very useful in areas where coverage is weaker with in-circuit or inspection. Keysight continues to offer functional test solutions in a number of industries which continue to see that need for performance validation.

Las Marias: It is now an accepted fact that ATE can be integrated into an automated electronic assembly line. However, testing in an automated environment provides new challenges, or opportunities, for both the ATE vendor as well as the end user. Having said that, what are the factors to consider before selecting a test/inspection vendor and implementing a functional test strategy?

Chari: This is an interesting question. There are multiple factors to be considered when selecting an appropriate test vendor to implement a functional test strategy. Firstly, the measurement science is a very critical base component which have to meet the needs of the products to be tested. Secondly, you need to look at the reliability of the solution, because in manufacturing, you don’t want failures, you want your test solutions to be running effectively for long periods of time, with the ability to identify product faults more effectively. Thirdly, you need a good strategy for fixturing and connecting the tester to the devices under test. For that, you have to be aware if your test vendor has considered this, and has the ecosystem to support your test needs during implementation.

Las Marias: What best practices should customers consider to improve their PCBA testing and inspection process?

Chari: One of the best practices for improving PCBA testing starts with DfT—design for test. You need to plan for the test and enable the test. Keysight has recently introduced some very good DfT tools for boundary scan, which customers can deploy. This is very critical in order to have the most effective PCBA testing processes. The second best practice is to try and standardize your test strategy, especially for functional tests. Many customers like to develop custom solutions for every product, and this does not allow reuse. Innovative customers have created standard test platforms which can be reused for different applications. This also allows customers to plan their test assets more effectively. For instance, Keysight has a functional test solution for automotive based on PXI. We have helped leading automotive customers implement such standardized functional test platforms for their long term success.

Las Marias: What are some of the mistakes you’ve seen others in your industry make that you’re determined to avoid?

Chari: In their desire to save costs, sometimes industry participants may compromise on their test strategy, which becomes a costly mistake. Cost of test is a small component compared to cost of customer dissatisfaction upon finding defective products. Thus, it is very important for the industry to avoid using strategies which compromise test in their pursuit to reduce cost. We can reduce cost of test via various other techniques such as automation, improving test coverage, integrating more testers into a single test environment. For instance, you could test a product with a manufacturing defects analyzer which provides basic testing, but it may not catch most of the defects found in the industry today. You could use an in-circuit tester and combine it with some functional test capabilities and multiple test stations, thereby reducing your cost of test, and enabling better quality.

In the very cost-competitive consumer products sector, we have seen some customers relying on inspection and functional tests, only to experience defects escaping which lead to costly warranty issues. They have since re-introduced in-circuit test, which is a very viable and cost-effective quality assurance tool. Compromising on test is a mistake—the cost of escapes as well as the loss of customer faith and satisfaction will always outweigh the cost of test.

Las Marias: Where is the test and inspection industry headed? What is your outlook for the industry?

Chari: The test and inspection industry is a mature industry with a few strong players. The industry will continue to be challenged by new technologies such as the Internet of Things, Industry 4.0, connected cars and 5G. With our strong focus on R&D and immense real-time experience in working alongside our customers, Keysight is gearing up to address these technology challenges.

Editor's Note: This article originally appeared in the July 2016 issue of SMT Magazine.

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