The process specifications for aerospace PCB (printed Circuit Board) assembly are extremely strict to ensure high reliability, high stability and high performance in extreme environments. The following is a detailed summary of the aerospace PCB assembly process specifications:
First, general requirements
Comply with standards: The assembly of aerospace PCBS must comply with relevant international, national and industry standards, such AS AS 9100 (based on the ISO 9001 standard, specifically developed for the aerospace industry), IPC (International Electronics Industry Connectivity Association) standards, etc.
Reliability first: Due to the particularity of the aerospace environment, PCB assembly must ensure extremely high reliability, capable of withstanding extreme conditions such as high temperatures, strong radiation, and severe vibration, and avoiding faults such as open circuits and short circuits.
Lightweighting and miniaturization: Under the premise of ensuring performance, efforts should be made to reduce weight and volume as much as possible to adapt to the limited space and load capacity of aerospace vehicles.
Second, materials and selection
PCB board
Plates with high dielectric constant, low loss, high heat resistance and good mechanical strength should be selected, such as FR-4 (a composite of glass fiber cloth and epoxy resin), PTFE (polytetrafluoroethylene), etc.
For applications that require higher heat resistance, metal-based PCBS (such as aluminum or copper substrates) or ceramic substrates can be selected.
The Tg value (glass transition temperature) of the sheet should be selected based on the actual usage temperature to ensure that it does not deform or soften at high temperatures.
Components and Materials:
All components and materials must comply with aerospace standards and possess properties such as high-temperature resistance, radiation resistance, and vibration resistance.
Redundant design should be carried out for key components to enhance the reliability of the system.
Avoid using materials containing harmful substances such as lead, mercury, cadmium, etc., to ensure environmental protection and human health.
Third, design and layout
Multi-layer board design: Aerospace PCBS typically adopt multi-layer board design to enhance circuit density, reduce wiring length, and lower signal interference.
Signal integrity: Through reasonable layout and wiring, ensure the integrity and accuracy of signal transmission. Avoid problems such as signal crosstalk, reflection and attenuation.
Thermal design
High-temperature devices should be placed in positions conducive to heat dissipation, such as air outlets or heat sinks.
Large-area copper foil should be connected to the pad through heat insulation tapes to avoid local overheating.
For devices that require heat dissipation, reasonable heat dissipation paths and structures should be designed.
Electromagnetic Compatibility (EMC)
Reduce electromagnetic radiation and electromagnetic interference through reasonable layout and wiring.
For sensitive circuits, shielding measures should be taken, such as using shielding covers and shielding wires.
Fourth, manufacturing and assembly
Manufacturing process:
Advanced manufacturing processes and equipment are adopted to ensure the quality and performance of PCBS.
Strictly control the manufacturing process, including etching, drilling, copper plating, solder mask and other procedures.
Assembly process:
The soldering of components should adopt reliable soldering processes, such as reflow soldering and wave soldering, etc.
For devices that require high-precision soldering, such as BGA (Ball Grid Array package) and QFN (Square Flat pin-less package), advanced soldering equipment and processes should be adopted.
Before welding, the components should be cleaned and pre-treated to ensure the welding quality.
Quality Control
Conduct full-process quality monitoring of the manufacturing and assembly processes to ensure that each link complies with standards and norms.
Conduct comprehensive tests and inspections on the finished products, including appearance checks, electrical tests, environmental adaptability tests, etc.
Fifth, environmental adaptability test
High-temperature testing: Test the PCB in a simulated high-temperature environment to ensure stable and reliable performance under high temperatures.
Low-temperature testing: Test the PCB in a simulated low-temperature environment to ensure it can operate normally at low temperatures.
Vibration test: Test the PCB in a simulated vibration environment to ensure that no problems such as loosening or breaking occur under vibration conditions.
Radiation testing: For PCBS that need to resist radiation, radiation testing should be conducted to ensure stable performance in a radiation environment.
Vi. Other Requirements
Anti-static measures: Anti-static measures should be taken during the manufacturing and assembly processes to prevent static electricity from causing damage to PCBS and components.
Identification and documentation: Clearly identify and record PCBS and components to ensure traceability and ease of maintenance.
Training and Qualifications: Manufacturing and assembly personnel should possess the corresponding qualifications and training experience to ensure they can master the relevant processes and operating procedures proficiently.
