High-Performance Micro-D Connectors and Cables - Pan Pacific ...

Micro-D Mod 429 Space GradeMicro-DSpecial Appsand MODs3Magnetic permeability: Arenonmagnetic connectorsrequired?Spacecraft designers generally avoidthe use of ferromagnetic materials,which can become magnetized andcan interfere with sensitive instruments.Micro-D connectors do notcontain ferromagnetic materials,so magnetic permeability is not aconcern. MIL-DTL-83513 requiresa maximum permeability of 2 mu.Glenair hermetic Micro-D connectorsare made from Kovar ® alloy, a highlymagnetic material. The stainless steele-rings commonly used for Micro-Djackscrew attachment also exceed the2 mu requirement.4Cryogenic exposure: AreMicro-D connectors suitablefor -200° C. ?Micro-D connectors are rated to -55° C.Glenair has not performed testing belowthis temperature. EEE-INST-002 states“...experience has proven it is possible for(non-certified) connector types to be usedsuccessfully at cryogenic temperatures. Itis recommended that connector samplesshould be subjected to five cycles ofcryogenic temperature...(followed byexamination for cracks and DWV)”.5Materials: Micro-Dconnectors offer a variety ofmaterials and plating finishes.Which ones are recommendedfor space flight?NASA recommends electroless nickelplated connector shells and crosslinkedhigh strength ETFE (Tefzel ® ) wire.Cadmium plating is prohibited becauseit sublimates in a vacuum environment.Gold plating is acceptable but rarelyused on Micro-D connector shells.6Wire Corrosion: M22759/33irradiated Tefzel ® wire ispreferred for space applications.What about corrosion problemscaused by this wire?Does M22759/33 wire have anoutgassing problem?Irradiated Tefzel ® wire is known to causetarnishing and corrosion of metal partsin close proximity, usually in sealedbags. Both MIL-DTL-83513 and NASAEEE-INST-002 contain cautionarynotes regarding this problem. Wiremanufacturers have not been able toeliminate this problem, which mightbe caused by the insulation extrusionprocess. This corrosion problemis referred to as “wire outgassing”,which has led to confusion over theterm outgassing. This problem hasnothing to do with the ability of thewire to meet the TML and CVCMoutgassing requirements of ASTME595. M22759/33 irradiated Tefzelwire continues to be the wire of choicefor spacecraft. This wire complies withoutgassing requirements.The corrosion problemMicro-D connectors supplied as prewiredassemblies should not be storedin sealed bags for extended periods.NASA recommends that parts beinspected for shell discoloration (“a dull“gun metal” appearance) and contactcorrosion (“a flat black appearance”).Connectors with corroded contactsshould be scrapped.New Unit Pack MinimizesCorrosionGlenair has adopted a new packagingstandard to protect the connectorfrom tarnishing or corrosion. Figure 2shows Glenair’s standard packagingfor metal shell connectors suppliedwith M22759/33 wire. The connector iswrapped in Teflon ® tape and placed in aventilated sulpher-free paper envelope.Figure 2Teflon-wrapped Connector andPerforated Bag“Users are advised that someETFE insulations are knownto outgas trace amounts ofcorrosive fluorine over time.When this wire is used withnickel coated metal shellconnectors and stored insealed plastic or ESD bags,trapped fluorine can attackexposed metal shells andcontacts.”Excerpt from Note 9, Table 2,NASA EEE-INST-002K© 2011 Glenair, Inc. U.S. CAGE Code 06324Printed in U.S.A.GLENAIR, INC. • 1211 AIR WAY • GLENDALE, CA 91201-2497 • 818-247-6000 • FAX 818-500-9912www.glenair.comK-9E-Mail: sales@glenair.com