When discussions of semiconductors arise, the spotlight typically falls on the most advanced chips powering artificial intelligence or high-performance computing. Yet the real backbone of global infrastructure rests on legacy semiconductors. These chips, produced at mature nodes such as 28nm, 45nm, or 65nm, are critical for automobiles, industrial controls, defense systems, and healthcare devices. Shortages in these components can ripple across entire economies, halting auto production lines or delaying defense procurement. Erik Hosler, a strategist in semiconductor resilience, underscores that legacy chips form the quiet foundation of critical systems, and securing them is as important as advancing the frontier. His perspective highlights that resilience is not only about leading-edge competition but also about the steady supply of older, indispensable technologies.
This dependency is particularly acute in defense and aerospace, where platforms may remain in service for decades. Aircraft, satellites, and logistics systems often rely on chips designed years ago, making replacement or redesign difficult. The COVID-19 pandemic and rising geopolitical tensions revealed just how fragile these supply chains have become. Addressing this vulnerability requires coordinated strategies that go beyond national borders. Allied pooling of demand and investment offers a path to ensuring legacy chip supply remains resilient in the face of future disruptions.
The Overlooked Role of Legacy Chips
The public imagination often equates progress in semiconductors with shrinking transistor sizes and leading-edge breakthroughs. But while 5nm and 3nm chips power flagship smartphones and AI accelerators, legacy nodes continue to serve as the workhorses of the global economy.
Legacy chips are used in automotive electronics, industrial machines, and power systems. They regulate safety features, control engines, and manage communications between devices. In healthcare, they appear in diagnostic equipment and patient monitoring systems. In energy and transportation infrastructure, they provide reliability where durability matters more than innovative performance.
Because these systems prioritize stability and certification, they cannot quickly switch to newer designs. Instead, they depend on a consistent supply of proven, mature chips. Without them, entire industries face disruption, regardless of how advanced leading-edge nodes become.
The ADS Dependency Challenge
Dependency on legacy chips is especially concerning for defense and aerospace (ADS). Military platforms often have lifespans measured in decades, and their electronics are designed around chips that may no longer be in production at advanced foundries. Redesigning or requalifying systems for new chips is costly, time-consuming, and sometimes impractical.
Satellites, for example, rely on radiation-hardened chips produced at older nodes. Fighter aircraft depend on mature microcontrollers that have been tested and validated under extreme conditions. Logistics and command systems also rely on legacy semiconductors to ensure compatibility and security across platforms.
If supply chains for these chips falter, the consequences extend directly to national defense readiness. Relying on overseas suppliers, some located in geopolitically sensitive regions, creates risks that cannot be ignored. Ensuring access to trusted sources of legacy chips is therefore a strategic priority on par with leading-edge competition.
Lessons from COVID-19 and Geopolitics
The global semiconductor shortage that unfolded during the COVID-19 pandemic exposed how fragile the supply of legacy chips had become. Automakers were forced to halt production when they could not obtain simple microcontrollers, even as advanced chips remained available for other markets. The bottleneck highlighted how little attention had been paid to mature nodes in national strategies.
Defense procurement was also affected. Delays in chip supply slowed the delivery of critical systems, raising concerns about readiness at a time of rising geopolitical tension. Meanwhile, U.S.–China trade disputes underscored the risk of overreliance on suppliers located in regions where political dynamics could disrupt access.
These events demonstrated that supply chain resilience cannot be achieved by focusing exclusively on the frontier of semiconductor technology. The vulnerabilities of legacy chip supply chains can have equally significant consequences, particularly for industries where substitution is not an option.
Allied Coordination and Pooling Demand
Securing legacy chips requires more than national investment. Because fabs that produce mature nodes often operate on thin margins, sustaining them depends on consistent demand. It is where allied coordination can play a decisive role. By pooling demand across the U.S., Europe, Japan, South Korea, and Taiwan, governments and industries can ensure that legacy fabs remain economically viable.
Joint investment in dedicated legacy production facilities could provide secure and trusted sources for critical applications. These facilities would not compete with advanced fabs but complement them, ensuring that mature technologies remain available for defense and infrastructure.
Allied cooperation also provides opportunities for standardization and certification. By aligning security requirements and procurement processes, partners can reduce costs and improve trust. This approach mirrors strategies in other sectors, where shared infrastructure and standards increase resilience.
Pooling demand also addresses the reality that no single country has the scale to guarantee all of its needs. Semiconductor supply chains are global, and resilience depends on collaboration among trusted partners.
Building a Sustainable Security Framework
Ensuring resilience in legacy chip supply will require innovation across multiple dimensions. Simply keeping old fabs running is not enough. Efficiency must be improved, workforce pipelines must be maintained, and new tools must be adapted for older nodes.
Erik Hosler stresses, “It’s going to involve innovation across multiple different sectors.” Securing legacy chip supply will require collaboration between governments, industry, and academia, combining policy initiatives with technological solutions. It is not a matter of nostalgia for old nodes but a recognition that critical systems require innovation in how legacy production is sustained.
Programs to incentivize domestic production, combined with allied procurement agreements, can create sustainable markets for legacy chips. Verification frameworks and HBOM-style transparency could also ensure that these chips are not compromised. By integrating innovation with coordination, the U.S. and its allies can build a framework that secures the backbone of critical systems.
Securing the Backbone of Critical Systems
Legacy chips may not capture headlines, but they are indispensable to modern life and national defense. The systems that protect citizens, power economies, and sustain industries rely on mature semiconductors as much as on innovative nodes. The COVID-19 shortage revealed how vulnerable these supply chains are, and geopolitical tensions have amplified the urgency of securing them.
Addressing this challenge requires allied coordination, pooled demand, and long-term strategies that treat legacy chips as strategic assets. By sustaining trusted production, aligning standards, and innovating across sectors, nations can ensure that critical systems remain resilient.
Legacy chips are the quiet foundation of global infrastructure. Securing them is not a secondary priority but a principal component of national and economic security. With coordinated action, the U.S. and its allies can transform vulnerability into resilience, ensuring that the backbone of critical systems remains strong for decades to come.
