Raspberry Pi 4 and 5: Thermal Dissipation and Information Security

Index

1. Thermal Dissipation

   1. Comparison between Raspberry Pi 4 and 5
   2. Cooling solutions
   3. Dissipative materials
   4. Issues in industrial environments

2. Information Security

   1. Security standards
   2. Protection against tampering
   3. Encryption and authentication
   4. Secure Boot

The following page offers an in-depth look at the differences between Raspberry Pi 4 and Raspberry Pi 5 in terms of thermal dissipation and information security. Each section is structured in clear and concise subparagraphs, leaving space for explanatory images and summary tables to be integrated later.

Thermal Dissipation

Comparison between Raspberry Pi 4 and 5

The Raspberry Pi 5 has significantly higher power consumption and heat generation compared to the Raspberry Pi 4. Under maximum load, a Pi 5 can draw up to ~15W, about double the typical ~7.5W of the Pi 4 (Raspberry Pi 5 Vs Raspberry Pi 4: The Detailed Differences & Comparisons). This power increase translates to higher operating temperatures: while the Pi 4 often manages to keep temperatures under control with passive solutions, the Pi 5 tends to heat up more and necessarily requires active cooling in continuous load scenarios to avoid thermal throttling (Raspberry Pi 5 vs Raspberry Pi 4 Model B - Pi My Life Up). In practice, with a Pi 4, a small heatsink is often sufficient (or even no addition for light applications), but the Pi 5, thanks to its more powerful processor (+600 MHz) and increased performance, needs a more robust cooling system to manage the extra heat generated (Raspberry Pi 5 vs Raspberry Pi 4 Model B - Pi My Life Up). It’s no coincidence that the Raspberry Pi 5 design introduced a dedicated fan connector (4-pin) specifically to facilitate the use of active cooling systems from the start (Raspberry Pi 5 vs Raspberry Pi 4 Model B - Pi My Life Up).

Cooling solutions

There are various solutions to keep the operating temperature under control, which can be divided into passive cooling and active cooling:

• Passive cooling: consists of using heat sinks (generally metal) and design considerations to dissipate heat without moving parts. A heat sink increases the dissipating surface and, if well coupled to the chip via thermal pads or thermal paste, can reduce temperature peaks by about 5–10°C (The best way to keep your cool running a Raspberry Pi 4 | Jeff Geerling). However, without some airflow, the effectiveness remains limited: it’s important that there is natural convection (e.g., ventilation holes in the case) or forced convection, otherwise the heat remains trapped (The best way to keep your cool running a Raspberry Pi 4 | Jeff Geerling). Purpose-designed aluminum cases, like the well-known Flirc case, function as large passive heat sinks themselves: thanks to their all-metal construction, they can dissipate heat very efficiently – almost on par with active fan solutions (The best way to keep your cool running a Raspberry Pi 4 | Jeff Geerling). These solutions are completely silent and maintenance-free, ideal for many applications where a slight temperature increase is acceptable but noise or moving parts should be avoided.

• Active cooling: uses fans or other devices to generate airflow or actively transfer heat. Even a small 5V fan mounted on the heat sink or in the case can drastically lower temperatures and avoid any thermal throttling. For example, advanced solutions like the ICE Tower cooler (which combines a heat pipe and fan) manage to keep the Raspberry Pi processor below 50°C even under maximum load (The best way to keep your cool running a Raspberry Pi 4 | Jeff Geerling), practically close to ambient temperature (The best way to keep your cool running a Raspberry Pi 4 | Jeff Geerling). This highlights how active cooling can maximize the device’s performance while keeping the CPU within ideal thermal ranges. The trade-off is fan noise and greater complexity (fan power supply, possible mechanical failures over time). In the case of the Raspberry Pi 5, the use of a fan is strongly recommended to fully exploit its performance: as mentioned, the new 4-pin header allows connecting a PWM fan controlled directly by the board, modulating the speed based on temperature and keeping the system within ~45-55°C under control (Raspberry Pi 5 vs Raspberry Pi 4 Model B - Pi My Life Up). In summary, active cooling guarantees wider thermal margins and stability even in the most demanding applications, at the cost of minimal additional bulk and noise.

Dissipative materials

The materials used in heat sinks and thermal interfaces significantly influence the effectiveness of dissipation and the operating temperatures of the Raspberry Pi. The two most common metals for heat sinks are aluminum and copper. Copper has a significantly higher thermal conductivity (about 231 BTU/(hr·ft⋅°F) compared to ~136 for aluminum, meaning aluminum has ~60% of copper’s conductivity) (Copper vs. Aluminum Heatsinks: What You Need to Know). In practice, with the same dimensions, a copper heat sink transfers heat more efficiently than an aluminum one. However, aluminum is much lighter (density ~2700 kg/m³, about 30% of copper) and decidedly cheaper (about one-third the cost of copper per volume) (Copper vs. Aluminum Heatsinks: What You Need to Know) (Copper vs. Aluminum Heatsinks: What You Need to Know). For this reason, the vast majority of commercial heat sinks for Raspberry Pi are made of aluminum: they offer a good compromise between thermal efficiency, reduced weight, and low cost. Copper is used in special or high-performance solutions (for example, some cooling kits use a copper base in contact with the CPU and aluminum fins, or copper heat pipes) where every degree less is important.

Another crucial aspect is the thermal conductive materials used between the chip and heat sink: thermal paste, thermal pads, or adhesives. A good thermal interface reduces the resistance to heat transfer. Ceramic or metal-based thermal pastes generally offer better conduction than pre-applied adhesive pads. For example, it has been observed that small heat sinks sold with pre-glued adhesive pads can result in temperatures 5–10°C higher compared to using a good quality non-adhesive thermal paste (How bad/good is cooling on the Raspberry pi 4?). In the Raspberry Pi context, thermal pads are often preferred for ease of installation (they are clean and easy to apply), but to maximize dissipation, it’s advisable to replace them or supplement them with a thin film of high-performance thermal paste. There are also advanced materials like pyrolytic graphite sheets or graphene pads, capable of conducting heat in-plane with very high conductivity (hundreds of W/mK), used to distribute heat uniformly over larger surfaces. In summary, the choice of heat sink material (copper vs. aluminum) and thermal interface (pad vs. paste vs. special solutions) can affect operating temperatures by several degrees. For thermally critical applications, it’s advisable to opt for quality heat sinks (perhaps with copper inserts) and high-performance thermal interfaces to ensure maximum cooling efficiency.

Issues in industrial environments

The use of Raspberry Pi in industrial environments or otherwise harsh conditions requires additional considerations regarding thermal dissipation. In such contexts, the ambient temperature can be high (for example, inside non-air-conditioned electrical cabinets, facilities with furnaces, outdoor environments in the sun, etc.) and well above the typical 20-25°C of an office. It’s important to remember that the Raspberry Pi uses commercial-grade electronic components: for example, the Ethernet/USB controller of many models is qualified only up to 70°C ambient, while the SoC (CPU) can operate up to ~85°C (How Hot Is Too Hot for Raspberry Pi? - element14 Community). In a hot industrial environment, the sum of high ambient temperature and the heat generated by the workload on the Pi can push components close to or beyond these limits, with the risk of throttling and possible malfunctions (How Hot Is Too Hot for Raspberry Pi? - element14 Community). For this reason, in 24/7 scenarios at high ambient temperatures, it’s essential to oversize the dissipation: for example, by using larger heat sinks, perhaps connected to metal chassis, and providing forced ventilation or heat pipe cooling systems to the outside of the cabinet. Often, Raspberry Pis intended for industry (like Compute Modules in industrial boxes) are specified to operate up to ~60°C ambient with adequate cooling (How Hot Is Too Hot for Raspberry Pi? - element14 Community), and it’s prudent to maintain a margin from the maximum limits of the chips to ensure longevity.

Other critical environmental factors are dust and humidity. Airborne dust, typical of many production environments, can deposit on the Raspberry Pi and especially on heat sinks and fans, reducing their effectiveness. A thick layer of dust on the fins of a heat sink acts as a thermal insulator, preventing heat from dissipating properly. Furthermore, conductive dust (for example, metallic) could cause short circuits if it accumulates on the board, while oily or humid dust can accelerate corrosion. In very dusty environments, it’s advisable to adopt closed and filtered cases: for example, IP65 or similar enclosures, which prevent dust from entering, or ensure regular cleaning operations (compressed air blowing) to remove accumulations from cooling systems. High humidity and condensation also represent a danger: water (especially with impurities) is conductive and can cause serious short circuits or damage to electronic components (humidity can damage raspberry). In environments with high relative humidity, when the temperature drops (for example, at night), condensation can form on the board. To mitigate this risk, it’s good practice to use sealed containers not subject to condensation (perhaps with small bags of silica gel inside to absorb residual moisture). Alternatively, you can consider a conformal coating treatment: a protective paint applied to the PCB of the Raspberry Pi that isolates it from moisture and prevents corrosion and short circuits (except for connection areas). In summary, in harsh industrial environments, it’s necessary to protect the Raspberry Pi both from external heat and environmental agents. This includes: generously sizing thermal dissipation, avoiding fans unless strictly necessary (since they aspirate dust, preferring passive solutions or heat exchangers), using industrial chassis certified against dust and water, keeping humidity away from the board, and providing periodic maintenance (cleaning filters/heat sinks) to ensure stable and safe operation over time.

Information Security

Security standards

When using Raspberry Pi in professional or industrial contexts, it’s important to frame it within an information security management system compliant with the main international standards, in particular ISO/IEC 27001 and IEC 62443.

ISO/IEC 27001 is an international standard for Information Security Management Systems (ISMS). It provides a rigorous methodological framework for protecting sensitive data and effectively managing information security (ISO 27001 - Information Security Management | BSI). Adherence to ISO 27001 implies the implementation of policies, procedures, and controls aimed at ensuring the confidentiality, integrity, and availability of information. In practice, for a Raspberry Pi-based project, following ISO 27001 means, for example: defining rules for access control (physical and logical) to the device, managing user accounts with least privilege principles, ensuring that data processed on the Pi is adequately protected (encryption, backup, etc.), assessing risks (through periodic risk assessments) and applying mitigation controls, all documented and subject to continuous improvement. ISO 27001 also requires tracking security incidents and conducting internal and external audits. Implementing such regulations in a Raspberry Pi context might mean, for example, including the Pi in the inventory of protected IT assets, applying security updates regularly, and having response plans in case the Pi is compromised. In essence, ISO 27001 helps build an organized process around security, ensuring that the use of the Raspberry Pi doesn’t become a weak link in the company network.

IEC 62443, on the other hand, is a family of standards specifically aimed at the cybersecurity of Industrial Automation and Control Systems (IACS), i.e., industrial control systems. This regulation (issued by ISA/IEC) defines detailed security requirements for components, systems, and processes in industrial automation, with the aim of protecting plants and machinery from cyber threats. A key concept of IEC 62443 is the definition of security levels (Security Levels, SL) from 0 to 4, where SL0 indicates absence of security requirements and SL4 the maximum level of protection. Each level imposes a series of controls and measures that must be implemented to declare a system compliant with that level (Security). For example, at higher levels, robust authentication, end-to-end encryption, network segregation, continuous monitoring, etc. are required. In the context of a Raspberry Pi used in industrial applications (such as data logger, process controller, IoT gateway, etc.), IEC 62443 provides guidelines on how to design and configure the system securely from the design phase (security by design). Implementing IEC 62443 could mean, for example, dividing the network into zones and conduits, putting the Pi in a protected zone with adequate firewalls; ensuring that the software on the Pi is developed taking into account known vulnerabilities (executing patch management and vulnerability assessments), and meeting technical requirements such as the presence of appropriate logging and intrusion detection systems. In practice, IEC 62443 applied to the Raspberry Pi world leads to adopting an “onion” architecture with multiple layers of defense – concept of defense in depth – and verifying the achievement of a certain Security Level through tests and certifications. The higher the level correctly implemented, the harder it will be for an attacker to compromise the industrial system (Security). In summary, while ISO 27001 is focused on organizational procedures for information security, IEC 62443 focuses on technical and process measures for the security of industrial systems. A Raspberry Pi project in an industrial context should ideally take both into account: having both solid organizational management (ISO 27001) and a robust technical architecture (IEC 62443).

Protection against tampering

Ensuring protection against physical tampering is essential when Raspberry Pis are deployed in accessible locations or not totally under control (e.g., remote stations, unmanned facilities, public environments). A malicious actor with physical access to the device could attempt to manipulate it, remove the SD card to clone it, or connect unauthorized peripherals. Below are some good practices and anti-tampering solutions to mitigate these risks:

• Secure location: install the Raspberry Pi in a physically protected location. Ideally, position it in a locked cabinet or in an area with restricted access to authorized personnel (Best Practices for Raspberry Pi Cybersecurity in 2024). Reducing direct physical access is the first simple step to prevent tampering.
• Tamper-proof case: use tamper-proof containers or frames. There are cases with security screws (for example, Torx screws with central pin) or padlocks, and you can add anti-tampering adhesive seals on the openings: if someone tries to open the case, the seal breaks evidencing the breach (Best Practices for Raspberry Pi Cybersecurity in 2024). Some security cases also offer thermal advantages (dissipation) integrated, combining physical protection and cooling in a single robust chassis (Best Practices for Raspberry Pi Cybersecurity in 2024).
• Protection of interfaces and SD card: to prevent logical tampering via physical ports, you can block or seal unused ports. For example, there are small locks or caps for USB/Ethernet ports, preventing the connection of unauthorized devices (Best Practices for Raspberry Pi Cybersecurity in 2024). The microSD card – which contains the operating system and data – should be made inaccessible: in critical contexts, you can seal the SD slot with resin/hot glue (knowing that this makes maintenance difficult), or opt for Pi models without a removable SD (e.g., a Compute Module with soldered eMMC).
• Active tamper detection: for high-security scenarios, you can employ anti-tamper sensors or hardware security modules that detect physical intrusions. Some systems integrate micro-switches that trip if the cover is opened, or monitor variations in luminosity, movement, or interruption of dedicated printed circuits. An advanced example is the Zymbit security module for Raspberry Pi, which includes a hardware “security supervisor” capable of perceiving the breach of the device perimeter and reacting (for example, deleting cryptographic keys or shutting down the system) (Security Module for Raspberry Pi - ZYMBIT). This physical device integrity technique continuously monitors physical integrity and allows to respond immediately to tampering attempts, drastically increasing the difficulty for an attacker to access the data even if they obtain the device (Security Module for Raspberry Pi - ZYMBIT).
• Defense layering: in a defense-in-depth perspective, it’s advisable to combine multiple levels of protection. For example, a Raspberry Pi in an unsecured environment might be: enclosed in a sealed metal box, wall-mounted (to prevent removal), with unused ports disabled at the software/hardware level, and equipped internally with a secure element module with data wipe functionality in case of intrusion. The more barriers are placed, the more time and resources an eventual aggressor will need to breach them. Ideally, the resistance time should be sufficiently high so that the attack is discovered (e.g., from a visual check of the broken seal or from an alert sent via network by a tamper sensor) before the data is compromised.

Encryption and authentication

Implementing robust encryption and authentication mechanisms is crucial to protect a Raspberry Pi-based system from unauthorized access, especially in cases where the device handles sensitive data or performs critical functions. Below are the main practices and technologies to consider:

• Full disk encryption: Protecting the SD card or storage device with full disk encryption helps ensure that, even if the storage is physically removed and connected to another computer, the data remains inaccessible without the decryption key. In Raspbian/Raspberry Pi OS, full disk encryption can be implemented through LUKS (Linux Unified Key Setup), particularly by encrypting the root partition while keeping the boot partition unencrypted. This approach requires entering a decryption password at startup but guarantees that, at rest, the data is fully protected. For unattended systems that need to reboot automatically, you can use hardware security modules (like Zymbit) that store encryption keys securely and release them to the system only if the physical environment meets specific integrity criteria.

• File and folder encryption: In scenarios where full disk encryption isn’t feasible, selective encryption of sensitive data using tools like eCryptfs or EncFS offers a good alternative. This approach creates encrypted containers or directories where confidential information can be stored. The system boots normally, and the encrypted areas are mounted only when needed, minimizing the exposure of decryption keys.

• Secure communications: All data transmitted to and from the Raspberry Pi should be encrypted, particularly over networks. This involves:

  • Implementing TLS/SSL for web interfaces and APIs
  • Using SSH keys instead of passwords for remote access
  • Enabling VPN tunnels for remote management
  • Implementing protocols like MQTT with TLS for IoT applications

• Multi-factor authentication (MFA): Adding layers beyond simple password authentication significantly increases security. For Raspberry Pi systems, this could include:

  • Hardware tokens like YubiKey
  • Time-based one-time passwords (TOTP)
  • Biometrics where feasible (for manned stations)
  • Location-based or network-specific authentication

• Secure key management: Properly managing cryptographic keys is as important as the encryption itself. Avoid hardcoding keys in software or configuration files. Instead:

  • Use hardware security modules (HSMs) like the aforementioned Zymbit or a TPM (Trusted Platform Module)
  • Implement secure key rotation policies
  • Utilize key derivation functions to generate keys from master keys
  • Consider integrating with enterprise key management systems for industrial deployments

• Access control: Implement granular permissions based on the principle of least privilege. Each service, user, or process should have only the minimum access rights necessary to perform its function. For Linux-based Raspberry Pi systems, this means properly configuring user accounts, groups, and file permissions, potentially using mandatory access control systems like SELinux.

• Certificate-based authentication: Especially for IoT deployments with multiple Raspberry Pi devices, implementing a Public Key Infrastructure (PKI) with device certificates enables secure, scalable authentication without shared secrets. Each device receives a unique identity certificate during provisioning, which it then uses to authenticate to services and other devices in the network.

Secure Boot

Ensuring that a Raspberry Pi boots only trusted software is fundamental for maintaining system integrity, especially in sensitive applications. Secure Boot is a process that verifies each component of the boot chain is authentic and unmodified before execution. While the Raspberry Pi doesn’t natively support UEFI Secure Boot like some PCs, several approaches can achieve similar security objectives:

• Verified Boot Chain: The Raspberry Pi Compute Module 4 (CM4) offers an optional eMMC memory that can be write-protected after programming, creating a more tamper-resistant boot media compared to removable SD cards. When paired with a custom carrier board that includes boot firmware verification, this setup approaches a verified boot sequence.

• Bootloader Protection: For standard Raspberry Pi models using SD cards, you can configure the boot process to load only signed firmware and kernel images. Tools like U-Boot can be customized to verify signatures on kernel images before booting them. This requires setting up a cryptographic signing process for your OS images and configuring the bootloader to check these signatures.

• Read-Only Root Filesystem: Mounting the root filesystem as read-only prevents runtime modifications to system files. This can be complemented with an overlay filesystem for necessary write operations, with changes being discarded upon reboot. This approach ensures that even if an attacker gains access during runtime, persistent modifications to the system remain difficult.

• Hardware-Backed Boot Security: The Zymbit security module, specifically designed for Raspberry Pi, offers hardware-backed secure boot capabilities. It can:

  • Store boot measurements (hashes of boot components)
  • Verify the integrity of the boot chain
  • Prevent the system from booting if tampering is detected
  • Securely release encryption keys only to a verified OS

• Boot Attestation: Implementing remote attestation allows a trusted server to verify the boot state of a Raspberry Pi. The device sends cryptographic measurements of its boot components to the server, which compares them against known-good values. Systems that fail attestation can be quarantined from sensitive resources or triggered to reinstall from a trusted image.

• Physical Boot Protection: For physical security, consider:

  • Epoxy-sealing the SD card slot after installation
  • Using tamper-evident seals on device enclosures
  • Installing the Pi in lockable, monitored enclosures
  • Disabling unused boot methods (USB boot, network boot) in device tree configurations

• Secure Provisioning Process: Establish a controlled environment for initial device setup, where boot media are prepared on secure systems and then transferred to Raspberry Pi devices using a chain of custody. This “secure provisioning” ensures that only authorized images ever execute on your devices.

For the highest security applications, a layered approach combining multiple methods provides the best protection against both software attacks and physical tampering attempts. Regular security audits should test the effectiveness of your secure boot implementation and identify potential vulnerabilities in the boot chain.