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EUROPEAN STANDARD EN 50389
NORME EUROPÉENNE
EUROPÄISCHE NORM September 2005

ICS 49.060
English version
Space product assurance –
Wire-wrapping of high-reliability electrical connections

Conformité des produits spaciaux - Raumfahrt-Produktsicherung –
Connexion par enroulement Lötfreie elektrische Drahtverbindungen
des connexions électriques hoher Zuverlässigkeit
de haute fiabilité
This European Standard was approved by CENELEC on 2005-08-01. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in two official versions (English, German). A version in any other language
made by translation under the responsibility of a CENELEC member into its own language and notified to the
Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden,
Switzerland and United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2005 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 50389:2005 E
Foreword
This European Standard was prepared by the Technical Committee CENELEC TC 107X, Process
management for avionics (former CENELEC BTTF 91-3).
The text of the draft was submitted to the formal vote and was approved by CENELEC as EN 50389 on
2005-08-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2006-08-01

– latest date by which the national standards conflicting

with the EN have to be withdrawn
(dow) 2008-08-01
1)
It is based on a previous version originally prepared by the ECSS product assurance working group,
reviewed by the ECSS Technical Panel and approved by the ECSS Steering Board. The European
Cooperation for Space Standardization (ECSS) is a cooperative effort of the European Space Agency,
National Space Agencies and European industry associations for the purpose of developing and
maintaining common standards.
This European Standard is one of a series of space standards intended to be applied together for the
management, engineering and product assurance in space projects and applications.
Requirements in this European Standard are defined in terms of what shall be accomplished, rather than
in terms of how to organize and perform the necessary work. This allows existing organizational
structures and methods to be applied where they are effective, and for the structures and methods to
evolve as necessary without rewriting the standards.
The formulation of this European Standard takes into account the existing EN ISO 9000 family of
documents.
———————
1)
ECSS-Q-70-30A.
- 3 - EN 50389:2005
Contents
Introduction.5
1 Scope.5
2 Normative references .6
3 Terms, definitions and abbreviated terms .7
3.1 Terms and definitions .7
3.2 Abbreviated terms .8
4 Preparatory conditions.8
4.1 Hazards, health and safety precautions .8
4.2 Facility cleanliness .8
4.3 Environmental conditions .8
4.4 Lighting requirements.9
4.5 Configuration of process/workpiece .9
4.6 Cleaning.9
4.7 Tools and equipment .9
4.7.1 General.9
4.7.2 Cutting tool .9
4.7.3 Insulation strippers.9
4.7.4 Wire-wrapping tools .10
4.7.5 Unwrapping tools .11
4.8 Tool calibration.12
4.9 Wire-wrap process certification.12
4.10 Test monitoring equipment .13
5 Materials selection .13
5.1 Wire .13
5.1.1 General.13
5.1.2 Conductor .13
5.1.3 Wire insulation .13
5.2 Terminal post .14
5.3 Wire to terminal post combinations.16
6 Wire-wrap operation .16
6.1 Preparation for wire-wrapping.16
6.2 Process .16
6.3 Wire-wrap criteria .18
6.3.1 Usage of wrap levels.18
6.3.2 Number of turns on terminal post .19
6.3.3 Positioning and regularity of wrap connection.19
6.3.4 Wire routing .19
6.3.5 Rework.19
6.3.6 Wire-wrap and solder connections onto the same terminal post.20
7 Test methods .20
7.1 General .20
7.2 Workmanship .20
7.3 Stripping force.20
7.4 Unwrapping test .22
7.5 Connection resistance .22
7.6 Gas-tightness test .23

7.7 Metallography.24
7.8 Records of tests .24
8 Acceptance criteria.25
8.1 Visual inspection .25
8.2 Performance tests .26
8.2.1 General.26
8.2.2 Stripping force test.26
8.2.3 Unwrapping test .27
8.2.4 Connection resistance test .27
8.2.5 Gas-tightness test .27
8.2.6 Metallography .27
9 Quality assurance.27
9.1 General .27
9.2 Data .27
9.3 Nonconformance .27
9.4 Calibration.27
9.5 Traceability .27
9.6 Workmanship standards .29
9.7 Operator and inspector training and certification.29
9.8 Inspections.29
9.8.1 Visual inspection .29
9.8.2 Process control .29
10 Verification .30
10.1 General .30
10.2 Temperature cycling.30
10.3 Vibration.30
Annex A (informative) Daily process control sheet for test samples.31
Bibliography.32

Figure 1 — Single wire-wrapped connection to square terminal and reference corner .6
Figure 2 — Examples of approved wire-wrapping tools .11
Figure 3 — Hand unwrapping tools .11
Figure 4 — Minimum wrapping length on terminal post for each wire gauge.15
Figure 5 — Terminal post dimensions over minimum wrapping length
for each terminal size .15
Figure 6 — Wire-wrap connection process .17
Figure 7 — Position and regularity of wrap connection.18
Figure 8 — Stripping force test fixture.21
Figure 9 — Connection resistance test.22
Figure 10 — Gas-tightness test result .23
Figure 11 — Typical cross-section of wire-wrap (×64) .24
Figure 12 — Wire-wrap rejection criteria which require reworking of the connection.26
Figure 13 — Guide to quality assurance during wire-wrapping .28

Table 1 — Wire size to terminal post combinations .16
Table 2 — Minimum number of wire turns on terminal post .
...