Properties and Applications of Automotive Printed Circuit Boards
The popularity of printed circuit boards for vehicles can be attributed not only to its functionality, but also because of its many other benefits. For example, automotive PCBs are improving the security features of vehicles, PCBs are also bringing comfort with the addition of air-conditioning systems, audio, and video entertainment.
Read on to learn more about automotive printed circuit boards.
What is Automotive PCB
Automotive PCBs are the circuit boards used in automotive electronics from engine controls, anti-lock brake systems, GPS, to rearview cameras and front lights. Safety is the most important consideration for automotive PCB design and manufacturing.
And as we add more heads-up displays, windshield overlays, in-cab navigation systems and other electronics to help us drive or relax as we drive, the demand for reliable PCBs that don’t interfere with other systems is going to continue to rise.
The Role of Electronic Systems in Automobiles
Application of electronic systems in automotive aims to increase auto performance, covering three aspects: environmental improvement, security enhancement and convenience and comfort.
● Environment improvement refers to fuel saving, tail gas reduction, fuel transformation from gasoline, natural gas, bio-fuel to hybrid power and pure power. Electric vehicles, thus, have become a strategic direction for the automotive industry.
● Security enhancement lies in traffic accident reduction, ranging from airbag, radar monitoring, stereo camera, infrared monitoring, and automatic avoidance to autonomous driving. Currently, autonomous vehicles are attracting majority attention and invest from the globe.
● Convenience and comfort is generally rooted in audio, video display, air-conditioner, computer, mobile communication, internet, navigation and electronic toll collection for considerations of convenience and humanization.
As the backbone of electronic devices, PCBs (Printed Circuit Boards) applied for automotive have to meet the requirement listed above as well.
Role of Printed Circuit Boards in Automotive Industry
As automotive industry is progressively marching towards technological advancements and innovations, several applications in today’s automobiles are based on electronic control for their proper operation. Automotive PCBs or electronic control circuits are offering reliable and high-grade performance while providing control systems for issues like pollution, fuel economy and safety norms. PCBs create the basic foundation for interconnecting varied electronic parts and processes in a vehicle.
Performance Properties of Automotive PCBs
As combinations of mechanical and electronic devices, modern vehicle technologies integrate both ancient and traditional techniques and up-to-date scientific technologies. Different parts in modern vehicles depend on electronic devices with different functions, leading to applications of PCBs with different missions.
Based on distinction in terms of substrate material of PCBs for automotive, they can be classified into two categories: inorganic ceramic-based PCBs and organic resin-based PCBs. The leading property of ceramic-based PCBs is high heat resistance and excellent dimensional stability, applicable for engine systems in highly-thermal environments. Nevertheless, ceramic-based PCBs feature bad manufacturability, leading to a high cost of circuit boards. With the development of newly-developed resin substrate with increased heat resistance, resin-based PCBs are mostly applied in the majority of modern vehicles.
What Applications of the Automotive PCB
Printed circuit boards can also be used in the audio and video equipment found in cars. Printed circuit boards for vehicles can also be used for global positioning systems or GPS. Aside from such, other applications include antilock brake systems, communication equipment, power converters, engine coolant level monitors, engine timing systems, LED brake lights, power distribution junction box, remote diagnostic systems, security systems, and transmission sensors, among others. It can be stated that when it comes to applications, PCBs could be considered as the backbone of the electrical system.
The belows is the list of the main applications of automotive PCBs.
1. GPS kit&ECU modules.
2. Displays (Digital)&Sensors of transmission.
3. Radar system&Audio and stereo components.
4. AC/DC converters&Engine controls.
5. Engine timing system&LED system.
6. Occupant detectors&Power distribution board.
Manufacturing Features of Automotive PCBs
Similar with military radar, as near-field radar, automotive anti-collision or predictive emergency braking system depends on PCBs to transmit microwave high-frequency signals. Thus, substrate materials with low dielectric loss are suggested, with PTFE (polytetrafluoroethylene) normally applied. Different from ordinary FR-4 as substrate materials, PTFE or similar high-frequency materials calls for distinct manufacturability naturally. For example, special drilling speed is required in the process of via drilling.
Heavy copper PCBs
Vehicles tend to generate more heat due to their high electronic density and power. With the number of hybrid power and all-electric vehicles rising, more advancing power transmission systems are demanded, which also calls for more electronic functions. It thus means higher demand for heat dissipation capability and larger current. To achieve that, the thickness of copper in PCBs should be increased or copper leads and metal are embedded in multi-layer PCBs.
It’s easy to fabricate heavy copper double-layer PCBs while it’s quite difficult to fabricate heavy copper multi-layer PCBs. The key point lies in heavy copper graphics etching and heavy copper gap filling.
Inner circuit of heavy copper multi-layer PCBs is heavy copper. Afterward, graphics transferring requires heavy film with extremely high corrosion resistance. Etching time should be long enough and etching device and technical condition should stay in an optimal state in order to ensure excellent circuits of heavy copper.
Because there’s a huge difference between inner conductor and insulator substrate material surface and ordinary multi-layer PCB stack up fails to make resin fully filled in, causing the generation of cavities, thin prepreg is then suggested containing a high amount of resin. Some multi-layer PCBs contain inner circuit with different copper thickness so that different prepregs can be used for areas with large distinction and small distinction.
Embedded component PCBs were first applied in cell phones to increase assembly density and reduce the product’s overall size, which is essentially important for other electronic products as well. That’s why embedment technology is used in automotive electronic devices.
Based on component embedment methods, there’re many embedded PCB manufacturing options:
● Groove is milled first then SMDs are assembled through wave soldering or conductive paste.
● Thin-film SMDs are first assembled on inner circuits through wave soldering.
● Thick-film components are printed on the ceramic base.
● SMDs are assembled through wave soldering and then resin is used for packaging. This type of embedded PCB is more compatible with the demands of vehicles such as heat resistance, humidity resistance and anti-shock, with high reliability.
Similar with smart phones or tablet computers in terms of functions of entertainment and communication, vehicles call for HDI PCBs as well. As a result, microvia drilling, electroplating and interconnection technologies have to be applied in automotive PCBs.
Type of PCB substrates that can be used in the Automotive PCBs
Ceramic PCB substrates are manufactured using alumina and aluminum nitride, so PCBs made from these substrates are used in the engine compartment to withstand high-temperature changes. Polytetrafluoroethylene (PTFE) substrates are good at incurring high-frequency variations, so they are usually found in vehicle safety systems. Metal-substrate PCBs are used in Antilock brake systems since metal provides good electrical insulation, thermal conductivity and acts as an excellent heat sink. Copper PCBs are used for safety and signaling system, because of their capability for high temperature, high frequency, and high current variations.
As a rule of thumb, all automotive PCBs must pass the stringent thermal cycling test, thermal shock test, and temperature humidity bias (THB) test before taken into consideration. Nowadays, automobiles are becoming more advanced with the introduction of PCBs for drowsy driver alert, blind-spot detection, and more.
Implementation of PCBs in automobiles increases auto-performance in terms of environment protection (halogen-free PCBs), security enhancements through controlled monitoring, and comfort that includes entertainment, mobile communication & the internet.
Compatible PCB types for Automobiles
For speedometers and air conditioners single-sided double layer PCBs (rigid/ flexible) are usually sufficient. Double-layer PCBs, Multi-layer PCBs or Flexible PCBs can serve significantly for Car stereo & monitoring systems. On the other hand, Multi-layer PCBs, HDI PCBs or Flexible PCBs are suitable for Automotive communication devices; wireless location appliances, and security control systems. Metal-core PCBs or Rigid-flex PCBs are generally implemented to design Engine system and power transmission control system while Embedded PCBs are incorporated in Vehicle power controller and navigation devices.
There are flexible PCBs also found in car electronics front dashboard, connecting large LED, LCD display to the processor board, or connecting various electronic modules each other by flexible PCBs. Flexible PCBs are light weight and can be adjusted/flexed inside the small space available in car deck/dashboard. The combination of rigid and flexible PCBs called Rigid-Flex PCBs are also found in Automotive PCBs.
Creating Your Next Automotive PCB
When you’re ready to get your next big idea to the market, Unitepcb is here to be your preferred PCB partner. With engineering and design services that focus on the automotive space, we’re here to assist you in maintaining high standards of reliability while cutting costs.
Test, modify and finalize your component development, plus make any modifications you need for added system support with our advanced prototyping methodology. You’ll put the final touches on your next automotive innova.