Device robustness, reliability and safety over the life of medical products are key concerns for the medical industry, particularly when it comes to active implantable medical devices, devices that administer drugs, or provide life support functions. The business needs to reduce time to market and stay ahead of the competition creates pressures to shorten design cycles while still complying with diverse safety and regulatory directives. Costly product recalls and liability litigation creates a particularly precarious arena for new product introduction - or even affecting minor design changes to existing products. As medical equipment design innovations become more complex, how can product reliability and ruggedness be assured without becoming cost prohibitive?
Accelerated stress testing (AST) is rapidly being adopted by the medical device industry because it provides manufactures the ability to exceed design margins and satisfy corporate profitability mandates. Not only do AST test methods - HALT (Highly Accelerated Life Testing) and HASS (Highly Accelerated Stress Screens) - increase operational margins and product reliability, but also detect and control process variability, including those of upstream suppliers.
HALT is a proven method developed by ESPEC Qualmark that enables manufacturers to find design defects and weaknesses in electronic and electromechanical assemblies - fast. It represents a paradigm shift from “low stress-high cycle” to high stress-low cycle” testing methodologies, subjecting products to stress extremes beyond that which would be encountered in normal use. By stimulating products beyond their design limits, latent design flaws can be found and fixed, and operating margins extended before a product goes to manufacturing. This results in a much more robust product with an assured ruggedness that can significantly minimize exposure to failure recall. HALT testing typically takes 3-5 days to find design deficiencies that would take traditional approaches weeks or months to accomplish. In fact, without the combined stresses delivered by HALT, as many as 32% of design failure modes would potentially be missed by traditional design verification testing.
HALT is not a design verification tool. HALT was developed specifically to ferret out latent flaws missed by other methods. In fact, HALT and/or HASS is recommended for all medical device electronics in classes I-III (FDA criticality classification) by Justiniano and Gopalaswamy in their book Practical Design Control Implementation for Medical Devices.
With the extended useful life of today's medical devices, sustaining and manufacturing engineers are confronted with obsolescence issues and parts shortages, creating a constant stream of ECO's (Engineering Change Orders). HASS provides a dependable methodology for ensuring that newly introduced part substitutions, and their manufacturing process, does not adversely affect product reliability. HASS prevents the shipment of latent product defects that are responsible for infant and OOB (out of box) failures that occur when using standard production tests such as burn-in, ICT (in circuit testing), or bench tests. Without HASS, medical device products are subject to increased warranty costs, customer dissatisfaction, and substantially higher stakes for product recall. HASS, then, becomes a crucial asset in the manufacturing process for reducing likelihood of process-induced flaws that could be introduced by remote contract manufacturers.
As medical device technology advances, product reliability and safety issues become more complex. Now more than ever, medical device manufacturers are challenged to provide profits in an era of constrained R&D budgets, reduced or limited reimbursements, and liability litigation. By introducing HALT and HASS into the design and manufacturing process, companies are able to meet business objectives, reduce exposure to recalls, and provide a quality product that will service the medical industry reliably for extended periods of time.