Important Considerations for designing and deploying Automotive PCBs
Latest self-driving vehicles and advanced driver assistance features are leading the expansion of Automobile PCBs in the market. Maintaining safety standards are critical while designing and deploying Automotive PCBs and should meet the IPC class 3 standard. It is necessary to use a simulation-driven development process to achieve the required PCB performance.
The automotive PCBs are extensively used in systems handling transmission control, engine and emission supervision, lighting, GPS, etc. They improve the vehicle performance in various aspects like environmental, security, and convenience.
- Saving fuel consumption, using alternate sources like natural gas, bio-fuel or electric power can help in the environmental improvement.
- Usage of a stereo camera, infrared monitoring, and airbag features can drastically enhance the safety of the driver and passengers.
- Audio, video, air conditioners, navigation, and the internet are the commonly expected comforts in the automobile industry.
Automotive PCBs are designed to be highly reliable in harsh environments like extreme temperatures, vibration, exposure to chemicals, dust, etc. They should be adaptable to varying environments. Lightweight, small size, and durability are the significant features of automotive PCBs.
TS16949:2009 is the internationally recognized Quality management system specification for the automotive sector. It is based on regulations of ISO9001 and highlights quality variation, defect prevention, and supply chain waste management of automotive components. The latest standard certification required in the automotive industry is IATF16949.
Automotive PCBs are used in different segments of a vehicle. For example:
- Communication devices, security control systems use HDI and Flex PCBs
- Power transmission control, engine system requires Rigid-flex or Metalcore PCBs
- Car indicator, headlight circuits can use LED PCBs
Automotive PCBs are used for transportation purposes and are concerned with the security and convenience of the customers. This demands a thorough reliability check on both the mechanical and electronics section of the vehicle. Before deploying the PCBs, proper PCB prototyping is done here to ensure reliability of the PCB.
Important Design Considerations for Automotive PCBs:
Critical features like an emergency braking system or anti-collision device rely on the transmission of high-frequency signals. Selecting substrates with a low dielectric loss can improve the speed of signal transmission. For example, PTFE (PolyTetraFluoroEthylene) is a suitable choice as it has a very low dielectric loss factor with improved signal performance.
Advanced automotive PCBs are all-electric or autonomous vehicles having high power requirements which further increases the demand for heat dissipation. To meet these thermal and large current requirements, the copper thickness has to be increased on the board. A good stack-up design considering the copper weight in different layers is essential.
Component placement and routing strategies are critical in automotive circuit design. Mutual inductance can introduce error voltage or current to the adjacent circuits. It is sensitive to circuit spacing and inductance loop area. This issue can be addressed by providing large areas around inductors and by placing the inductors perpendicular to each other. This reduces the signal crosstalk.
Similar to incorrect inductor placement causing mutual inductance, leads that are close to each other are affected by mutual inductance as well. A uniform return path for signals under the lead can reduce the parasitic inductance effect. In RF circuits, lead coupling issue is common with sensitive components. An integrated grounding under the leads can improve the circuit performance.
To reduce the parasitic inductance effect, suitable layout strategies have to be followed like choosing a thinner copper coating for through holes and creating an inductance module for through holes in sensitive areas of the circuit.
A uniform ground plane can avoid several noise issues in a high-frequency circuit board design. While designing the ground and filling in the PCB layout, providing a continuous low-impedance ground plane is recommended.
To increase the circuit density and reduce the board size, embed technology can be used in automotive applications. SMDs are assembled using the wave soldering technique and resin is applied for packing. This type of PCB assembly increases product reliability with enhanced heat and shock resistance, suitable for automotive applications.
Advanced Automotive systems:
The automotive sector has transformed drastically in the last few decades. Along with passenger safety, the recent focus is on environmental impact and user convenience. This has emphasized the development of electric vehicles (EV) and autonomous vehicles (AV) in the automobile sector. These advanced automotive systems have their challenges of high voltage and current requirements, thermal management concerns, etc.
IPC-6012DA Automotive standard provides the necessary specifications to ensure the reliability of the PCBs operating in the vibrating and harsh thermal environment of electronic interconnects in the automotive industry.
PCB manufacturers have to implement an advanced, simulation-driven development process that can evaluate all the aspects of automotive PCB performance. Apart from following design and layout guidelines, a complete CAD model simulation is necessary to analyze the thermal and vibration impact. A series of thermal tests along with structural analysis and fatigue analysis is mandatory while building a PCB for automotive application.
Many circuits present in an automobile can generate EMI and interrupt surrounding devices. Designing and testing automotive PCBs to have minimum EMI issues is essential. There are ISO testing standards specifically for the automotive industry like ISO 11451(testing the immunity of the vehicle to different disturbances) and ISO 11452 (immunity of the electronic components used in vehicles to various sources of interference).
The global automotive PCB market is extensively growing with the rising inclination towards advanced technology-based vehicles. PCB manufacturers are adapting to the latest trends and investing heavily to match the requirements of luxury features in automobiles. Advanced Driver Assistance Systems (ADAS) application is one of the latest trends in the automotive industry. Also, the growing demand for safety features is driving the production of high-performance automotive PCBs. Many Government bodies have directed the safety features with regulations on anti-brake systems, airbags, etc.
An experienced contract manufacturer can assist in all stages of automotive PCB development and deployment. The contract manufacturer should have a well-defined manufacturing process with modern facilities. The equipment used and the staff involved should be capable of building reliable products. The contract manufacturer should have a robust supply chain with a good network of component vendors. Collaborate with one such assembly provider to easily build an advanced automotive PCB.
