Aerospace & Defense Technology - May 2022 - 22

Design Guidelines for
Military and Aerospace PCBs
P
rinted Circuit Boards are the
heart of the electronics industry.
They are used in a diverse
range of applications starting
from consumer electronics to complicated
aerospace and military domains.
The design considerations vary according
to the requirements of the end
product. Military and aerospace PCBs
follow the most critical and strict design
standards as they have to operate in
tough environmental conditions with
exposure to vibrations, contaminations,
and extreme temperatures.
Military and aerospace PCB designs
have to meet regulatory standards from
the IPC trade association, military-specific
standards by the US Department of
Defense (DoD), and quality management
standards for the aerospace industry set
by organizations like NASA, DoD, and
Federal Aviation Administration (FAA).
Based on the severity of the application,
IPC has categorized electronic
products into three classes. While the
general consumer products come under
Class 1, the dedicated service products
are placed under Class 2. The military
and aerospace PCBs fall under Class 3,
which has a high-reliability requirement
as detailed in IPC6012 Class 3/A.
Military and aerospace are the two
sectors that demand superior performance
and high precision PCB design.
To ensure zero downtime, these PCBs
adhere to the IPC-A-610E standard and
go through quality checks at each stage
starting from the design, PCB fabrication,
assembly, and final deployment of
the product. Several factors influence
the development process of the military
and aerospace PCBs.
Factors That Impact the Design and
Assembly of Military and Aerospace PCBs
1. Extreme Temperature
Exposure to harsh temperatures
(ranging between -150°C to +200°C) is
one of the critical factors that affect
aerospace and military PCB design.
a) PCB Material Selection:
Substrate material used in military-grade
PCBs should withstand
extreme temperatures. Depending on
the operating temperature of the
PCB, a substrate with suitable heat
resistance (Tg) value has to be chosen.
A minimum of 20°C margins have to
be included. For example, if the
required operating temperature is
160°C, then it is recommended to use
a substrate with Tg=180°C.
High-temperature laminates with
copper or aluminium substrates are
suitable for these applications.
Materials like FR408, Pyralux AP,
Nelco N7000-2HT all have high Tg
values.
b) Coating and Surface Finish:
The military/aerospace PCBs are introduced
to moisture and humidity along
with the peak temperature. To protect
the PCB components from these external
factors, conformal coating of acrylic
resin by spray method is recommended.
The suggested surface finishes
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ADT Feature 5 - PCB Design 0522_1.indd 22
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Aerospace & Defense Technology - May 2022

Table of Contents for the Digital Edition of Aerospace & Defense Technology - May 2022

Aerospace & Defense Technology - May 2022 - Intro
Aerospace & Defense Technology - May 2022 - Cov 4
Aerospace & Defense Technology - May 2022 - Cov 1
Aerospace & Defense Technology - May 2022 - Cov 2
Aerospace & Defense Technology - May 2022 - 1
Aerospace & Defense Technology - May 2022 - 2
Aerospace & Defense Technology - May 2022 - 3
Aerospace & Defense Technology - May 2022 - 4
Aerospace & Defense Technology - May 2022 - 5
Aerospace & Defense Technology - May 2022 - 6
Aerospace & Defense Technology - May 2022 - 7
Aerospace & Defense Technology - May 2022 - 8
Aerospace & Defense Technology - May 2022 - 9
Aerospace & Defense Technology - May 2022 - 10
Aerospace & Defense Technology - May 2022 - 11
Aerospace & Defense Technology - May 2022 - 12
Aerospace & Defense Technology - May 2022 - 13
Aerospace & Defense Technology - May 2022 - 14
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Aerospace & Defense Technology - May 2022 - 16
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Aerospace & Defense Technology - May 2022 - 18
Aerospace & Defense Technology - May 2022 - 19
Aerospace & Defense Technology - May 2022 - 20
Aerospace & Defense Technology - May 2022 - 21
Aerospace & Defense Technology - May 2022 - 22
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Aerospace & Defense Technology - May 2022 - 25
Aerospace & Defense Technology - May 2022 - 26
Aerospace & Defense Technology - May 2022 - 27
Aerospace & Defense Technology - May 2022 - 28
Aerospace & Defense Technology - May 2022 - 29
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Aerospace & Defense Technology - May 2022 - 35
Aerospace & Defense Technology - May 2022 - 36
Aerospace & Defense Technology - May 2022 - 37
Aerospace & Defense Technology - May 2022 - 38
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Aerospace & Defense Technology - May 2022 - 40
Aerospace & Defense Technology - May 2022 - 41
Aerospace & Defense Technology - May 2022 - 42
Aerospace & Defense Technology - May 2022 - 43
Aerospace & Defense Technology - May 2022 - 44
Aerospace & Defense Technology - May 2022 - 45
Aerospace & Defense Technology - May 2022 - 46
Aerospace & Defense Technology - May 2022 - 47
Aerospace & Defense Technology - May 2022 - 48
Aerospace & Defense Technology - May 2022 - Cov 3
Aerospace & Defense Technology - May 2022 - Cov 4
https://www.nxtbook.com/smg/techbriefs/22ADT10
https://www.nxtbook.com/smg/techbriefs/22ADT09
https://www.nxtbook.com/smg/techbriefs/22ADT08
https://www.nxtbook.com/smg/techbriefs/22ADT06
https://www.nxtbook.com/smg/techbriefs/22ADT05
https://www.nxtbook.com/smg/techbriefs/22ADT04
https://www.nxtbook.com/smg/techbriefs/22ADT02
https://www.nxtbook.com/smg/techbriefs/21ADT12
https://www.nxtbook.com/smg/techbriefs/21ADT10
https://www.nxtbook.com/smg/techbriefs/21ADT09
https://www.nxtbook.com/smg/techbriefs/21ADT08
https://www.nxtbook.com/smg/techbriefs/21ADT06
https://www.nxtbook.com/smg/techbriefs/21ADT05
https://www.nxtbook.com/smg/techbriefs/21ADT04
https://www.nxtbook.com/smg/techbriefs/21ADT02
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