What are the Requirements for Space Grade Connectors?

Sometimes, I think it would be utopian to find myself on an isolated island with some enchanted animals, coconut trees, and clear blue waters. Aside from having to catch an occasional fish, my biggest decision would involve when and how long I should just swing in the hammock. This fantasy can persist for quite a while before I realize that I would not have access to the Internet and, of course, be completely cut off from humanity. As I could not abide this for very long, I guess I should simply adopt the philosophy that, at the very least, no man is an island.

The same is true for printed circuit boards (PCBs). In most cases, boards require connectors for power or to send and receive signals to other boards or electronic devices. For commercial applications, the greatest connector-related design concern is probably ensuring adequate edge clearance. Although this is a concern for connectors used on aerospace platforms as well, there are additional requirements that must be met to qualify your board’s connectors as space-ready. Let’s first define space grade connectors and then look at the requirements for their deployment.

What are Space Grade Connectors?

The development of electronics and PCBs for use in aerospace vehicles and platforms is subject to rigorous regulatory oversight. This means the design, component procurement, and manufacturing stages must meet high bars for quality and reliability in order to adhere to specific standards and guidelines. This same level of scrutiny applies to space-grade connectors.

Types of Space Grade Connectors

For commercial electronics products, there are a wide range of common connector types. For these products, connectors are typically not faced with environmental hazards, such as extreme temperatures and vibration, as is the case for connectors in critical systems like automotive and aerospace. Connectors deployed in aerospace have constraints related to size, shape, and reliability in harsh environments.

As space is always limited on spacecraft,  the rule of thumb for connectors is: the more compact the better. Equally important is weight. The more mass a vehicle or platform has, the more energy is required to move it; therefore, lightweight materials like plastics and elastomers are often used. These materials may present outgassing issues over time, which is why outgas testing is a significant qualifying requirement for space grade connectors. With these considerations, the types of connectors that are utilized is limited to the following categories:

• Circular, power (denoted as Type C)
• D-Subminiature Rectangular (Type D)
• Microminiature Rectangular (Type M)
• Printed circuit, Rectangular (Type P)
• Coaxial (Type RF)
• Rack and panel, rectangular (Type A)
• Hermetic (Type H)

As shown above, the types of connectors for electrical connections is limited. All of the types may be used to connect circuit boards, whether embedded in a rack, panel, or alternative mounting.

Requirements for the Deployment of Space Grade Connectors

To meet the stringent requirements for aerospace deployment, space grade connectors must meet performance metrics defined in a number of regulatory documents. The most important of these is probably the Electronic Components Industry Association publication EIA-364 Electrical Connector/Socket Test Procedures Including Environmental Classifications, with the last revision F in 2014. This document defines specific testing requirements for space grade connectors and includes the test types listed below.

TESTING REQUIREMENTS FOR SPACE GRADE CONNECTORS
Type of Test	Standard	Description
Visual and dimensional	EIA/ECA-364-18B	Verification of materials, dimensions, specifications, design, construction, finish, and identification
Durability	EIA-364-09C	No electrical or mechanical defects for at least 500 cycles
Mating/unmating force	EIA-364-13E	Force requirement varies according to connector type
Withstanding voltage	EIA-364-20D	Ability of the connector to withstand momentary overvoltage
Insulation Resistance	EIA-364-21E	Resistance determination for 500V DC at high and nominal temperatures
Contact resistance	EIA/ECA-364-23C	Based on connector type
Humidity	EIA-364-31C	Based on environment and connector type
Mechanical shock	EIA-364-27C	No discontinuity > 1 µs with 100 mA applied
Vibration	EIA-364-28F	Based on environment
Thermal cycling	EIA/ECA-364-110	Ability to withstand temperature extremes based on environment

The table above includes tests that are required for all connector types. For tests applicable to only certain connector types, refer to the complete listing of tests.