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:
I. General requirements
Compliance with standards: Aerospace PCB assembly 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 priority: Due to the particularity of the aerospace environment, PCB assembly must ensure extremely high reliability, able to withstand extreme conditions such as high temperature, strong radiation, violent vibration, and avoid faults such as open circuit and short circuit.
Lightweight and miniaturization: under the premise of ensuring performance, reduce weight and reduce volume as much as possible to adapt to the limited space and load of aerospace spacecraft.
2. 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 (glass fiber cloth and epoxy resin composite), PTFE (polytetrafluoroethylene) and so on.
For occasions where higher heat resistance is required, metal-based PCB (such as aluminum substrate, copper substrate) or ceramic substrate can be selected.
The Tg value of the plate (glass transition temperature) should be selected according to the actual use temperature to ensure that it does not deform and soften at high temperatures.
Components and Materials:
All components and materials must meet aerospace standards and have characteristics such as high temperature, radiation and vibration resistance.
Key components should be redundant to improve system reliability.
Avoid using materials containing harmful substances (such as lead, mercury, cadmium, etc.) to ensure environmental protection and human health.
3. Design and layout
Multi-layer board design: Aerospace PCBS usually use multi-layer board design to improve circuit density, reduce wiring length, and reduce signal interference.
Signal integrity: Through reasonable layout and wiring, ensure the integrity and accuracy of signal transmission. Avoid signal crosstalk, reflection, attenuation and other problems.
Thermal design:
The high-heat device should be placed in a position conducive to heat dissipation, such as an air outlet or heat sink.
The large area of copper foil should be connected to the pad through the insulation zone to avoid local overheating.
For devices that need heat dissipation, a reasonable heat dissipation path and structure should be designed.
Electromagnetic Compatibility (EMC) :
Through reasonable layout and wiring, reduce electromagnetic radiation and electromagnetic interference.
For sensitive circuits, shielding measures should be taken, such as the use of shielding covers, shielding lines, etc.
4. Manufacturing and assembly
Manufacturing process:
Adopt advanced manufacturing process and equipment to ensure PCB quality and performance.
Strict control of the manufacturing process, including etching, drilling, copper plating, solder resistance and other processes.
Assembly process:
Components should be welded using reliable welding processes, such as reflow welding, wave soldering, etc.
For devices requiring high-precision welding, such as BGA (ball grid array package), QFN (square flat pin-free package), etc., advanced welding equipment and processes should be used.
Components should be cleaned and pre-treated before welding to ensure welding quality.
Quality control:
Quality control throughout the manufacturing and assembly process to ensure that every step complies with standards and specifications.
Conduct comprehensive testing and inspection of finished products, including appearance inspection, electrical testing, environmental adaptability testing, etc.
5. Environmental adaptability test
High temperature test: Testing the PCB in a simulated high temperature environment to ensure stable and reliable performance at high temperatures.
Low temperature test: The PCB is tested in a simulated low temperature environment to ensure that it can work normally at low temperatures.
Vibration test: The PCB is tested in a simulated vibration environment to ensure that there will be no problems such as loosening and breaking under vibration conditions.
Radiation testing: For PCBS that need to be resistant to radiation, radiation testing should be performed to ensure stable performance in a radiation environment.
6. Other requirements
Esd measures: Take ESD measures during the manufacturing and assembly process to prevent electrostatic damage to the PCB and components.
Identification and documentation: PCB and components are clearly identified and documented to ensure traceability and easy maintenance.
Training and qualification: Manufacturing and assembly personnel should have the appropriate qualifications and training experience to ensure that they can master the relevant processes and operating procedures.
To sum up, the process specification of aerospace PCB assembly involves many aspects, from material selection, design and layout, manufacturing and assembly to environmental adaptability testing, etc., all need to strictly comply with relevant standards and specifications. Only in this way can we ensure the high reliability, high stability and high performance of aerospace PCBS in extreme environments.
