Wednesday, May 18 2012 | Zulki Khan, NexLogic Technologies, Inc.
Mil/aero boards must meet the MIL-PRF-31032-1C fabrication standard and assembly standard IPC 610 Class 3 Rev. C. Beyond complying with these standards, you may likely consider mil/aero PCBs characterized by ratcheted-up specifications. In effect, a “beefed-up” PCB, with either through-hole or surface-mount components, means the EMS provider literally increases board specifications beyond the OEM’s minimum engineering specifications so that the board, and its end product, maintain high-performance and optimum reliability, regardless of environmental, terrain, or temperature conditions.
Successfully going above and beyond a mil/aero OEM’s board specification to assure optimum reliability is founded on design and manufacturing experience since no textbook examples exist from which to learn.
This extra edge on reliability assurance comes at a time when military and aerospace applications are trending toward smaller, less cumbersome communications gear like personal hand-held communications devices and mil/aero ruggedized versions of tablet computers (Figure 1).
Figure 1: Mil/aero applications trend toward small, but ruggedized, versions of tablet computers.
Punching in Extra Reliability
Three areas for injecting additional reliability are at board layout design, fabrication, and assembly with various key steps at these stages providing an extra 5 to 20% reliability factor, as the examples show in the chart below. In all cases, it is important for the EMS provider to consult the OEM customer to explain the importance of increasing a board specification and to obtain permission to proceed with a revised specification.
Figure 2: Going above and beyond the call: Increased PCB reliability can be added at key points at layout design, fabrication, and assembly stages.