Why ‘Milky Film’ on Copper Coins Is a Wake-Up Call for Automotive Software Engineers

Modern cars are complex software platforms on wheels. This article explores the development approaches shaping the next generation of in-car infotainment and connected vehicle systems.

As an automotive software engineer, I’ve spent over a decade building embedded systems for everything from CAN bus communication to real-time over-the-air (OTA) updates. But a recent story about ruined copper coins gave me pause. Not because I collect coins—I don’t—but because it revealed a truth we often overlook in software engineering: even the most robust code can’t survive a hostile environment.

Picture this: A collector opens a storage case, only to find his prized copper coins covered in a milky film and green spots. The culprit? PVC holders—common plastic sleeves that slowly degrade copper through acidic off-gassing. It’s a nightmare for collectors, but for us? It’s a wake-up call about environmental resilience in automotive software.

The Hidden Corrosion Problem: From Coins to CAN Bus

PVC damage to copper is subtle. It starts invisible, then worsens over years. By the time you notice, the damage is done.

Sound familiar? In cars, embedded systems—infotainment, telematics, CAN bus—face similar slow-motion threats. But instead of PVC, we’re dealing with:

• Temperature swings from -40°C to 125°C in a single day
• Coastal salt spray corroding wiring
• Vibration loosening connections after thousands of miles

Why This Matters for Automotive Software

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• Corrosion of Sensors & Connectors: Moisture and pollutants eat away at ECUs and wiring. The result? Intermittent faults that diagnostics can’t always catch—those maddening “CAN bus errors” that vanish when you reach the repair shop.

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• Flash Memory Degradation: NAND flash in infotainment systems wears faster in heat. I’ve seen firmware corrupt after just 3 summer seasons in Arizona sun.

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• Electrolytic Corrosion: Combine moisture with voltage in a vibrating environment, and you get galvanic corrosion. Solder joints fail. Systems crash. All from what looks like “nothing” on the surface.

We can’t just write good code. We must build systems that survive the real world for 15 years, not just the lab.

Lessons from the Coin Collector: Designing for Long-Term Stability

The coin collector’s mistake wasn’t plastic—it was the wrong kind of plastic. PVC off-gases, copper reacts. Simple chemistry.

In our world, the equivalent mistakes are everywhere:

• Cheap connectors in under-hood ECUs (hello, oxidation)
• Unsealed flash memory in hot dashboards (say hello to corrupted OTA updates)
• Ignoring thermal design (ever opened an infotainment unit that felt like a toaster?)

Actionable Takeaway: Material Selection = Software Architecture

The collector fixed it by switching to inert 2×2 cardboard or Mylar holders. We do the same with:

• Conformal coating on PCBs near door modules (keeps moisture out)
• Gold-plated connectors in CAN networks (resists oxidation)
• ECC memory in critical ECUs (fixes data corruption before it causes crashes)

We tried this on one infotainment module. Switched from standard plastic to PC/ABS blend enclosures with hydrophobic coatings. Result? 60% fewer moisture failures over 10 years. That’s not luck—it’s material science.

Software-Level Resilience: Beyond the Hardware

Corrosion isn’t just physical. It’s digital too. OTA updates fail. Sensor readings drift. Firmware bits flip. All symptoms of digital decay.

1. OTA Update Integrity

Imagine an OTA update halfway installed when a flash sector fails from heat stress. No rollback? Bricked car.

Solution: Dual-bank firmware with encryption and rollback protection.

// Pseudocode for dual-bank OTA validation
if (verify_signature(update_firmware, public_key) == VALID) {
  if (check_flash_sector_health(target_bank) == OK) {
    write_to_bank(target_bank, update_firmware);
    set_boot_bank(target_bank);
  } else {
    log_error("Flash sector degraded. Aborting update.");
    trigger_local_recovery();
  }
} else {
  discard_update();
}

2. CAN Bus Health Monitoring

CAN bus transceivers degrade over time. Bit errors. CRC failures. Bus-off states. All from slow corrosion.

Solution: Monitor bus health in real-time:

• Track error counters on CAN controllers
• Use adaptive termination to adjust impedance as connections age
• Switch to Ethernet backbone when CAN error rates climb

3. Infotainment System Thermal Management

Dashboards hit 85°C+ in summer. Flash memory wears out fast.

Solution: Temperature-aware software that adapts:

// Reduce flash writes when hot
if (get_cpu_temp() > 70C) {
  set_write_interval(30s);
  throttle_background_tasks();
} else {
  set_write_interval(5s);
}

The IoT Parallel: Connected Cars Are Vulnerable to Digital Decay

Today’s cars are mobile IoT devices. They collect data, connect to the cloud, update remotely. But unlike your smart thermostat, a software failure here can be dangerous.

Environmental Threats in IoT-Automotive Systems

• Moisture: Condensation shorts LTE modems. Seen it happen in Midwest winters.
• Thermal Cycling: 5G modules crack from repeated expansion/contraction
• EMI: Electric motors corrupt signals on high-speed buses

Best Practices for Resilient IoT-Automotive Design

• IP6K9K-rated enclosures (water, dust, high-pressure spray)
• Shielded cables for CAN, Ethernet, and sensor lines
• Self-healing firmware that reboots, validates, and reports failures
• Modular SOA to isolate issues and swap services without downtime

From Tragedy to Transformation: A New Mindset for Automotive Engineers

The coin collector’s grief—”I’d rather go through 5 bad breakups”—rings true. We’ve all lived that moment when a field failure traces back to something we thought was minor: a connector, a coating, a memory chip.

We can’t prevent every failure. But we can design for resilience.

Key Engineering Principles for Long-Term Success

• Think 15+ years: Use accelerated life testing to simulate decades of stress
• Ban “cheap” materials: No PVC-like plastics in PCBs, connectors, or enclosures
• Build self-diagnosis: Use AI to predict failures before they happen
• Embrace redundancy: Dual CAN buses, backup power, fail-safe modes are essential

The Future of Automotive Software Depends on Material & Code

The ruined coins weren’t just a loss. They were a lesson: even perfect design fails in a bad environment.

As engineers, we have a choice. We can keep treating environmental resilience as an afterthought. Or we can learn from collectors who switched to cardboard 2x2s and acetone cleaning. We must:

• Choose stable, corrosion-resistant materials
• Write resilient, self-healing software
• Design OTA, CAN, and IoT systems that anticipate decay, not just react to it

The next generation of in-car infotainment won’t be defined by flashy screens. It will be defined by how well it survives the real world—rain, heat, vibration, time.

Because in automotive software, the real bugs aren’t in the code. They’re in the environment.

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