Crystals, an abundant resource on Earth, are unique in that when subjected to mechanical stress or pressure, select classes of these structures create or change their electrical charge. This property is known as the piezoelectric effect. If you have designed electronic systems that required external synchronization or multiple timing, then you have implemented the inverse piezoelectric effect, where applying or changing the electrical charge across a crystal oscillator generates or changes the frequency of oscillation. What may not be as well-known is how important the piezoelectric effect is to aerospace electronics systems.
Piezotronics, which are electronic devices that utilize the piezoelectric effect, are used throughout deployed aerospace systems and aerospace simulators to monitor critical operations and provide abnormality warnings and alerts. Being deployed in the most unforgiving environment (space) means that aerospace systems are required to meet the highest standards for quality and reliability, which extends to subsystems, such as PCBs. Achieving these standards for your PCB piezotronics for aerospace necessitates that you and your critical system contract manufacturer (CM) work closely with a common purpose.
But before laying out guidelines for the design and manufacture of your piezotronic PCBs for aerospace, it is advisable to understand these electronic devices in greater detail.
What are Piezotronic PCBs?
The Piezoelectric Effect and Piezotronics
French scientist Pierre Curie1 and his brother Paul-Jacque were the first to experimentally demonstrate the piezoelectric effect in 1880. The piezoelectric effect is a natural property demonstrated by approximately 20 crystal classes including quartz, rochelle salt, topaz and others. These classes are unique in that a change in applied pressure results in a corresponding change in electrical charge. This naturally established change in charge is known as piezoelectricity.
The term piezotronics2 itself refers to the utilization of piezoelectricity, the resulting charge differential formed in a material due to mechanical stress, or more concisely, the piezoelectric effect, placed to control the flow of charge in an electronic device like a semiconductor. Piezotronic PCBs may be broadly defined as boards that contain piezotronic components or are part of a piezotronic device or system.
Piezotronic Devices for Aerospace Application
As the field of piezotronics is relatively new, the full range of components and devices that may evolve from this technology is, as yet, unknown. However, a number of devices, including sensors, accelerometers and signal conditioning devices, have been developed and are utilized by the aerospace industry for the following purposes:
- Systems Testing
- Rocket motor instability testing
- Cryogenic fuel monitoring
- Hydraulic pump analysis
- Engine vibration and pressure testing
- Force limited vibration
- Acoustic Stress
- Flight Testing
- Unmanned aerial vehicle (UAV) testing
- Ground Testing
- Ground vibration testing (GVT)
- Static load testing
- Fatigue testing
- Acoustic testing
- Environmental Testing
- Highly accelerated life testing (HALT)
- Highly accelerated stress screening (HASS)
Designing PCB Piezotronics for Aerospace Manufacture
As we can see from the above, piezotronic devices are implemented throughout the aerospace industry to provide critical data and information. Piezotronics PCBs are well-suited for aerospace applications due to their reliance on naturally occurring phenomena such as pressure and vibration. However, due to the extreme conditions that accompany space deployment, these devices must meet stringent and well-regulated development requirements. Let’s look at some of the most important attributes that your PCB piezotronics for aerospace design and manufacturing plan should include to ensure the success of your product development.
Make good component selections
Your selection of components should not be guided by cost alone. Although cost is important, fewer aerospace products are typically developed than for other industries like consumer electronics. It is vital for you to avoid counterfeit components that could stall your ability to supply aerospace organizations and result in shortages that may prevent you from meeting your customer delivery demands.
Understand and follow applicable standards
Components, devices and systems used in aerospace platforms must follow regulatory standards for quality management, supply chain monitoring, testing, documentation and reporting and other aspects of development. It is advisable to be familiar with the requirements, as well as their intent.
Plan for and utilize testing
The probability that your aerospace product will need to undergo testing is high. Therefore, you should leverage the manufacturing testing capabilities of your CM and plan for the eventuality of functionality and regulatory testing.
Work with a qualified CM
The importance of your choice for PCB fabrication and assembly services is difficult to overstate. The range of service, quality and capabilities among CMs is broader than you may realize and it is imperative that your CM employs quality control measures that will support you in delivering reliable aerospace industry compliant products.
Design for Excellence (DFX)
Your design should not be created in a vacuum. In fact, your board design should be guided by good design for manufacturing (DFM) practices, including design for assembly (DFA), and when necessary, design for testability (DFT), in accordance with your CM’s equipment capabilities and processes.
Piezotronics play a critical role in the aerospace industry. This relatively new class of components and devices is currently used for ground-based testing and in-flight operations. As usage grows, the need for qualified CMs to support your PCB piezotronics for aerospace development will expand as well.
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And to help you get started on the best path, we furnish information for your DFM and enable you to easily view and download DRC files. If you’re an Altium user, you can simply add these files to your PCB design software.