Test strategies are mandatory for every company, whether they are applying diagnostics in the development stage or ensuring quality during manufacturing. As such, it is virtually impossible to have a one-size-fits-all test strategy because there are so many variables and specifics. For example, because of their miniaturized and highly integrated components, circuit board test strategies require creative application of new tools and methods. Perhaps that explains why many companies, especially the small ones, agonize over the three major test considerations: cost, access, and coverage.

Product design companies recognize the need for testing in the development stage, but there is likely to be an internal debate about the number and cost of resources to be allocated for testing in the manufacturing stage. The salient point, regardless of the arguments, is that product testing is inescapable. To ignore manufacturing test requirements for whatever reason does not constitute an effective strategy.

A discussion of test cost is likely to take center stage whenever test priorities are considered. Companies do have an alternative to a Hobson’s choice between a costly investment in newly created test equipment and cutting corners by forgoing testing that should be conducted. That alternative is a test platform approach that maximizes test development investment and flexibility.

Benefits of a Platform Approach

Most OEMs and EMS providers can ill afford to absorb the costs associated with purchasing a suite of instruments to test all product scenarios. A number of test development teams have found the platform approach to be a cost-effective yet thorough testing alternative is the platform approach.

The platform is an assembly of off-the-shelf test equipment flexible enough to be modified to meet changing test requirements. Platforms are based on instrument architecture provided by a number of vendors that can grow as needed to meet new requirements. One example is a testing platform developed by a vendor more than 10 years ago that is still capable of conducting and accommodating new product tests. The platform is in its third generation, upgraded as new instrumentation has become available.

OEMs and, in particular, EMS providers, view the purchase of such platforms as budget-conscious investments in architecture that can support future growth. Test platforms can support multiple products, offering huge cost savings through reuse of capital investments.

Platform architecture and its inherent flexible standardization offer a number of benefits.

Familiarity. No multiple training programs or certifications are required, as operators can use the same test approach and interface for testing of multiple products. In essence, one platform can provide an organization-wide knowledge base.

Reuse. The architecture does not have to be reinvented with each new product or device, even if more-intricate test methods are required.

Reduced development schedule. Designers should find the period between concept and manufacturing will likely be lessened. Test developers can engage early to leverage the platform for performance and verification tests during early development.

Maintenance. Platforms contain readily available spares, saving time and expense.

Resolving Non-Recurring Engineering (NRE). NRE charges have always been the bane of product development, and with good reason. NRE represents the cost of developing a test solution for any new product—a cost that must then be factored to see if the product can still be profitable. Test strategies based on platform test solutions can help lower NRE test costs, as no new or minimal test platform development is required to accommodate new products.

Replication and support. Off-the-shelf platforms are assembled from parts in stock and can be built within weeks instead of starting over and building a new tester. For comparison purposes, new testers usually take 8–10 weeks to build, while one assembled following a platform blueprint normally requires only a four-week period.

Views on Testing Differ

Various stakeholders will have varying opinions on the necessity of specific tests. The product development team lead may focus foremost on minimizing cost, accepting and assuming quality as a given. The manufacturing team is likely to focus on production success as measured by the ability to meet or exceed yield targets for the device.

For medical devices, this sentiment is compounded by rigorous FDA expectations and proof of meeting a product’s critical function parameters. Focusing solely on cost could lead to manufacturing nightmares in which a reliable product cannot be produced, and focusing solely on yields could burden a new product introduction, squelching a program before it is able to launch. A compromise must be found through cooperative efforts between the product design and manufacturing teams.

For some companies, testing is not viewed as adding value. “If we build it right, we don’t need the test,” is the usual rationale. It’s a flawed supposition. Testing provides reassurance of good products and is the tool for gathering feedback necessary to tune product manufacturing. Testing reveals flaws that stem from product design, changing materials, and manufacturing.

Technology is advancing at high speed, especially in product and circuit board designs. Discreet components continue to shrink, processor speeds continue to increase, and area-array packages grow in density. The number of products relying on custom ASIC development is also a growing market. The demand for product miniaturization continues to accelerate. Building it right the first time is just as challenging now as when the circuit industry morphed from leaded to surface-mount components.

Today’s rapidly expanding technology has created challenges for product designers, who somehow must find board space for test point access. This is sometimes referred to as the real estate challenge. As boards get smaller, test points are more difficult to place. There appears to be a trend in this industry to reduce the number of test points based on circuit board density. The trend is driven by product size and economics, but it is not without risk. One of those eliminated points could lead to a missed diagnosis of a problem that adversely affects device functionality. Test strategy determination must include an impact assessment of reduced test access. There are multiple ways to test a product, but it is desirable for everyone to focus on the least costly means, which is to test a product early in the manufacturing process.

Despite the importance and inherent need for testing, many of the systems now available are prohibitively expensive. Virtual and small companies may be most challenged to embrace an appropriate test strategy due to the cost of traditional and new advanced test systems. Even a medium or large company may second guess the investment required for a test strategy to launch a low-volume product, for which the proportional costs for testing are high compared with a high-volume product launch.

Expensive test systems are likely to bust the development budget and the bottom line. One example is the trend to add cellular telephone functions to medical products such as implant monitors. Test systems for cellular telephony can be quite expensive, taxing even some medium-size companies’ budgets. Firms that have invested in earlier generation test equipment may find it to be incompatible with the latest operating systems. Information technology groups are always chasing the latest data protection schemes.

Upgrading test systems with the latest operating systems and applications to maintain vigilance presents new challenges for those responsible for sustaining test systems. A flexible test platform built to accommodate software upgrades is essential to the equipment reuse equation.

The Problem with Individual, Customized Tests

Every company presumably has a test strategy, whether the device is in the development or production stages. But before the strategy can be implemented, product variables such as physical size, test access, complexity, technology, and support have to be reviewed. Once those elements have been comprehensively factored, the strategy can be formulated. Less tangible but perhaps equally important factors include consideration of compliance to standards, forecast production volume, ease of defect detection, configuration requirements, data reporting and archiving, as well as package verification requirements.

The basic test strategy for most companies includes a board-level test prior to product assembly, followed by a subassembly test or multiple subassembly tests, if applicable, and finally a device-level functional test. For medical devices, for which quality is paramount, additional test methods are required. Test additions may include high voltage and isolation safety tests, product programming, end-item configuration, special functionality verification, and automated visual inspection. These additions compound the cost of testing, much to the chagrin of cost-conscious manufacturers and producers who view customization as entirely too costly.

GE Healthcare is a good example of an advocate for the application of a common test platform rather than individual, customized tests for each level of testing. Wesley Moreau, project leader for GE Healthcare Life Support Solutions, in Madison, WI, does not endorse the use of numerous and dedicated custom tests. Instead the firm has instituted a shared platform approach. "Otherwise, you're investing a lot of money into a one-use system, and that's not cost effective," Moreau says.

The Staffing Question

Each company, regardless of size, should have a testing team in position to thoroughly evaluate all the challenges associated with the introduction of a new medical device: technology, cost, and scheduling. The size of the team may have to be limited when the product under development is produced by a small- or medium-sized company. In fact, many companies might succumb to the pressure to have only a minimal test team due to the possibly prohibitive expense of having a skilled testing staff ready for development.

An alternative is to leverage test development staff at a manufacturing location or, more often, hire a contract manufacturer. A successful test development team includes a project manager, lead test-development engineer, test developers, a mechanical designer, a printed circuit board designer, and a quality assurance engineer. Few OEMs can afford to have such a team in house. Therefore, they should take advantage of services offered by electronic manufacturing service (EMS) providers who employ such teams.

A Platform Success Story

The experience of GE Healthcare with off-the-shelf test platforms can serve as a guideline for medical device companies considering this option. The company adopted a test platform to provide functional test solutions for multiple subassemblies across four product families. The test platform was configured with all necessary instrumentation to accommodate the test solutions. Capital equipment for this platform-based solution resulted in an estimated 38% reduction in cost when compared with a dedicated test solution, according to Moreau, the project leader. GE Healthcare estimated a 15% improvement in test development time as compared with a custom solution.  

“We have seen benefits in the form of cost savings and reduced need for floor space, as well as our turnaround time," says Moreau, who advises companies considering the approach to use a dedicated product test solution when planning long-term strategies and business partnerships as part of their decision making process.

Testing Leads the Way to Market Readiness

The test platform approach can resolve the primary testing conflicts of cost, access, and coverage. There is still a need to embrace the value of testing. Though advances in manufacturing processes have been unprecedented, the outcome has not rendered testing unnecessary. Technological advances have kept up, if not surpassed, manufacturing testing in recent years. Yes, manufacturing processes are pushing the envelope—all the more reason why they need tests to support them.

The good news for OEMs is that they no longer have to start from scratch and deal with long lead test development schedules, not to mention unacceptable costs, before getting their medical device to market. Most important, adoption of a test platform approach that can be easily modified to suit the particular product either in the development or manufacturing stages offers the opportunity to assess functionality throughout the development and manufacturing cycle.

For the mature medical firms that understand the necessity of testing early and for less experienced firms with fewer resources, the platform test approach will prove to be a wise investment. First, though, they have to accept testing as a prerequisite for any successful product launch.

Paul Schaffner is test development manager in Winona, MN, for Benchmark Electronics Inc. (Angleton, TX).
 

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