SIST EN 16602-70-30:2015

SLOVENSKI STANDARD
01-januar-2015
=DJRWDYOMDQMHYDUQLKSURL]YRGRYYYHVROMVNLWHKQLNL6SDMDQMH]åLþQLPRYLMDQMHP
NRQWDNWRYYLVRNR]DQHVOMLYLKHOHNWULþQLKNRQHNWRUMHY
Space product assurance - Wire wrapping of high-reliability electrical connections
Raumfahrtproduktsicherung - Umhüllung von Kabeln für hochzuverlässige elektrische
Verbindungen
Assurance produit des projets spatiaux - Enveloppe de fils pour connexion électrique à
fiabilité élevée
Ta slovenski standard je istoveten z: EN 16602-70-30:2014
ICS:
49.060 /HWDOVNDLQYHVROMVND Aerospace electric
HOHNWULþQDRSUHPDLQVLVWHPL equipment and systems
49.140 Vesoljski sistemi in operacije Space systems and
operations
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 16602-70-30
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2014
ICS 49.140
English version
Space product assurance - Wire wrapping of high-reliability
electrical connections
Assurance produit des projets spatiaux - Enveloppe de fils Raumfahrtproduktsicherung - Umhüllung von Kabeln für
pour connexion électrique à fiabilité élevée hochzuverlässige elektrische Verbindungen
This European Standard was approved by CEN on 11 April 2014.

CEN and 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 CEN-CENELEC Management Centre or to any CEN and CENELEC
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN and CENELEC member into its own language and notified to the CEN-CENELEC Management Centre
has the same status as the official versions.

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

CEN-CENELEC Management Centre:
Avenue Marnix 17, B-1000 Brussels
© 2014 CEN/CENELEC All rights of exploitation in any form and by any means reserved Ref. No. EN 16602-70-30:2014 E
worldwide for CEN national Members and for CENELEC
Members.
Table of contents
Foreword . 5
1 Scope . 6
2 Normative references . 8
3 Terms, definitions and abbreviated terms . 9
3.1 Terms defined in other standards . 9
3.2 Terms specific to the present standard . 9
3.3 Abbreviated terms. 10
4 Principles . 11
5 Requirements . 12
5.1 Preparatory conditions . 12
5.1.1 Hazards, health and safety precautions . 12
5.1.2 Facilities . 12
5.1.3 Tools and equipment . 13
5.1.4 Configuration of process and workpiece . 15
5.1.5 Wire-wrap process certification . 16
5.1.6 Requirements for new combinations of wire-wrap . 16
5.2 Material selection . 17
5.2.1 Wire . 17
5.2.2 Terminal post . 19
5.3 Wire-wrap operation . 22
5.3.1 Preparation for wire-wrapping . 22
5.3.2 Process and criteria . 22
5.3.3 Number of turns on terminal post . 24
5.3.4 Wire routing. 25
5.3.5 Rework . 25
5.4 Test methods . 26
5.4.1 General . 26
5.4.2 Stripping force . 26
5.4.3 Unwrapping test . 27
5.4.4 Connection resistance . 27
5.4.5 Gas-tightness test . 28
5.4.6 Metallography . 28
5.4.7 Records of tests . 29
5.5 Workmanship and acceptance criteria . 29
5.5.1 Visual inspection . 29
5.5.2 Replacement and rework . 30
5.5.3 Performance tests . 31
5.6 Quality assurance . 32
5.6.1 General . 32
5.6.2 Traceability . 32
5.6.3 Data . 33
5.6.4 Nonconformance . 33
5.6.5 Calibration . 35
5.6.6 Workmanship standards. 35
5.6.7 Operator and inspector training and certification . 35
5.6.8 Inspections . 36
5.7 Document requirements. 37
Annex A (informative) Procedure for wire-rapping . 38
Bibliography . 46

Figures
Figure 1-1: Single wire-wrapped connection to square terminal and reference corner . 7
Figure 5-1: Minimum wrapping length on terminal post for each wire gauge . 21
Figure 5-2: Terminal post dimensions over minimum wrapping length for each terminal
size . 21
Figure 5-3: Position and regularity of wrap connection . 24
Figure 5-4: Wire-wrap rejection criteria which require reworking of the connection . 31
Figure 5-5: Guide to quality assurance during wire wrapping. 34
Figure 5-6: Guide to quality assurance during wire wrapping. 34
Figure A-1 : Examples of approved wire-wrapping tools . 39
Figure A-2 : Wire-wrap connection process . 40
Figure A-3 : Hand unwrapping tools . 41
Figure A-4 : Example of a daily process control sheet for test samples . 43
Figure A-5 : Stripping force test fixture . 44
Figure A-6 : Connection resistance test . 44
Figure A-7 : Typical cross-section of wire-wrap (×64) . 45
Figure A-8 : Gas-tightness test result . 45

Tables
Table 5-1: Wire size to terminal post combinations . 22
Table 5-2: Minimum number of wire turns on terminal post . 25
Table 5-3: Minimum stripping force . 27
Table 5-4: Test current for connection resistance . 28

Foreword
This document (EN 16602-70-30:2014) has been prepared by Technical
Committee CEN/CLC/TC 5 “Space”, the secretariat of which is held by DIN.
This standard (EN 16602-70-30:2014) originates from ECSS-Q-ST-70-30C.
This European Standard shall be given the status of a national standard, either
by publication of an identical text or by endorsement, at the latest by April 2015,
and conflicting national standards shall be withdrawn at the latest by April
2015.
Attention is drawn to the possibility that some of the elements of this document
may be the subject of patent rights. CEN [and/or CENELEC] shall not be held
responsible for identifying any or all such patent rights.
This document has been prepared under a mandate given to CEN by the
European Commission and the European Free Trade Association.
This document has been developed to cover specifically space systems and has
therefore precedence over any EN covering the same scope but with a wider
domain of applicability (e.g. : aerospace).
According to the CEN-CENELEC Internal Regulations, the national standards
organizations of the following countries are bound to implement this European
Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
Scope
This Standard specifies requirements for preparing and assembling parts to be
joined by wire wrapping, as well as the selection, calibration, use and
certification of wire wrapping tools.
The covered wire-wrapped connections are illustrated in Figure 1-1.
This type of connection is similar to “Class A preferred” or “modified”
connection detailed in MIL-STD-1130, and NASA NHB 5300.4(3H).
Only previously tested and qualified wire-wrapped connections are covered by
this Standard, which includes four wire sizes from 24 AWG to 30 AWG, and
three terminal post sizes up to 1,78 mm maximum diagonal. A step-by step
procedure is covered in the informative Annex A.
The use of heavier gauge wire and larger terminals is not generally prohibited,
but it is considered unlikely that for such dimensions the method of
wire-wrapping would be chosen as the electrical interconnection technique.
Instead it is assumed that wire larger than 24 AWG will be multi-stranded and
terminated by soldering in conformance with ECSS-Q-ST-70-08, or by crimping
in conformance with ECSS-Q-ST-70-26.
Training and certification requirements for operators and inspectors are defined
in clause 5.6.7 and in ECSS-Q-ST-20.
With effect from the date of approval, this Standard announces the adoption of
the external document on a restricted basis for use in the European Cooperation
for Space Standardization (ECSS) system.
This standard may be tailored for the specific characteristic and constraints of a
space project in conformance with ECSS-S-ST-00.

Terminal post
End tail
Uninsulated wire turns
Insulated wire
Reference corner
(and at 1 below)
3 4
Shows either 3 or 4 corners of contact of insulation minimum ¾ turn of insulated
wire
Figure 1-1: Single wire-wrapped connection to square terminal and reference
corner
Normative references
The following normative documents contain provisions which, through
reference in this text, constitute provisions of this ECSS Standard. For dated
references, subsequent amendments to, or revisions of any of these publications
do not apply. However, parties to agreements based on this ECSS Standard are
encouraged to investigate the possibility of applying the most recent editions of
the normative documents indicated below. For undated references the latest
edition of the publication referred to applies.

EN reference Reference in text Title
EN 16601-00-01 ECSS-S-ST-00-01 ECSS system – Glossary of terms
EN 16602-20 ECSS-Q-ST-20 Space product assurance – Quality assurance
EN 16602-70-02 ECSS-Q-ST-70-02 Space product assurance – Thermal vacuum
outgassing test for the screening of space materials
EN 16602-70-38 ECSS-Q-ST-70-38 Space product assurance – High-reliability soldering
for surface-mount and mixed technology
ESSCC Generic Solid wires, electrical 350V, for wire wrapping
specification 3903
Terms, definitions and abbreviated terms
3.1 Terms defined in other standards
For the purpose of this Standard, the terms and definitions from
ECSS-S-ST-00-01 and ECSS-Q-ST-70-38 apply.
In particular from ECSS-Q-ST-70-38 the following term:
process identification document (PID)
NOTE The content of the PID is specified in
ECSS-Q-ST-70-38.
3.2 Terms specific to the present standard
3.2.1 a turn of wire
a wrap consisting of one complete single helical ring of wire wrapped 360
degrees around the terminal post, touching all four corners of the post.
NOTE For the purpose of counting turns, the number of
times the wrapped wire passes and intercepts the
reference edge of the terminal post after the first
intercept of uninsulated wire and terminal post,
constitutes the number of turns of uninsulated
wire in the connection.
3.2.2 end tail
end of the last turn of wire on the terminal post which can extend in a
tangential direction instead of resting against the post
3.2.3 gas-tight area
contact area between the terminal post and wire which excludes gas fumes
3.2.4 reference corner
corner of the terminal post at which the first turn of uninsulated wire contacts,
and from which the number of turns of the wrapped wire are counted.
3.2.5 terminal post
post of square or rectangular section onto which the interconnection wire is
wrapped.
3.2.6 wire-wrapped connection
connection consisting of a helix of continuous, solid, non-insulated wire tightly
wrapped around the terminal post to produce a mechanically and electrically
stable connection.
NOTE 1 The number of turns required will depend on the
gauge of wire used.
NOTE 2 All completed wraps have an additional minimum
of 3/4 turn of the insulated wire that is in contact
with at least three corners of the terminal post (see
Figure 1-1).
3.3 Abbreviated terms
For the purpose of this Standard, the abbreviated terms from ECSS-S-ST-00-01
and the following apply:
Abbreviation Meaning
AWG American wire gauge
ETFE ethylene-tetrafluorethylene (Tefzel)
NCR nonconformance report
PFA perfluoroalkoxy
PID process identification document
PTFE polytetrafluorethylene
PVDF polyvinylidene fluoride (Kynar)
QA quality assurance
RFA request for approval
RH relative humidity
Principles
The production of wire-wrapped connections is a relatively simple yet precision
method of fusion. Its use for high reliability space conditions affords high skills
of operators and inspectors as well as tooling and environmental controls to
produce continued high level quality. The following principles are laid down in
this Standard:
• Each tool is certified for each wire to post configuration; regular
calibration is mandatory.
• All material, including wire and post, requires approval and rigorous
inspection.
• A well-defined and documented process control document (PID) to
ensure consistency of production over extended periods.
• Operators and inspectors need experience and regular training and
certification.
• Frequent inline inspection and testing of wire-wraps validate continued
quality levels for the intended high reliability application.
Formal Quality Assurance and documentation will substantiate the achieved
level of compliance to the requirements within this Standard.
It is important to perform the work taking into account health and safety
regulations and in particular the national standards on this subject.

Requirements
5.1 Preparatory conditions
5.1.1 Hazards, health and safety precautions
a. Components, tools and controls shall be so located that personnel are not
exposed to hazards such as electric shock, cutting edges, sharp points or
toxic atmospheres.
b. Pneumatic air-powered wire-wrapping tools shall be connected to a
regulated, lubricated and filtered air supply, and disconnected when not
in use.
5.1.2 Facilities
5.1.2.1 Facility cleanliness
a. The supplier shall provide for a work environment in conformance with
the following:
NOTE Those requirements are in general met by using
cleanrooms. It is not, however, mandatory to
use a cleanroom.
1. The areas in which wire-wrapping is carried out are maintained in
a neat orderly fashion, with no loose material that can cause
contamination of the wire-wrapped connection.
NOTE For example: Dirt, dust, oils or clipped wires.
2. Furniture is kept to a minimum in the work areas and be arranged
to allow easy and thorough cleaning of the floor.
3. Working surfaces are covered with an easily cleaned hard top, or
have a replaceable surface of clean, non-corrosive silicone-free
paper.
4. Tools used in the wire-wrapping operation are clean.
NOTE For example: Excess lubricant is removed
before wire-wrapping starts.
5.1.2.2 Environmental conditions
a. The following environmental conditions at the wire-wrapping
workstations shall be established:
1. controlled environment which limits entry of contamination;
2. continuously controlled temperature and humidity as follows:
(a) room temperature: (22 ± 3) °C;
(b) relative humidity: (55 ± 10) %.
3. no exposure to draughts;
4. supply of fresh air through a filtering system to establish a positive
pressure difference to adjacent rooms; the exhaust air is restricted
to avoid turbulences.
5.1.2.3 Lighting requirements
a. Adequate illumination conditions of the wire-wrapping workstations
shall be implemented as follows:
1. light intensity with a minimum of 1080 lux on the work surface.
2. at least 90 % of the work area are shadowless and without severe
reflections.
5.1.3 Tools and equipment
5.1.3.1 Cutting tool
a. The selected cutting tool shall cut the conductor wire without causing
flattening of the wire.
b. Any tool not conforming with requirement 5.1.3.1a shall be removed
from the work area.
5.1.3.2 Insulation strippers
a. To avoid damage to the conductor, stripping devices, in particular
thermal and precision cutting devices, manual or automatic power-
driven shall
1. provide protection of the conductor wire;
2. avoid wire stretching by use of mechanical strippers;
3. avoid that the conductor is twisted, ringed, nicked, cut or scored
by the stripping operation.
b. Any tool not conforming with requirement 5.1.3.2a shall be removed
from the work area.
5.1.3.3 Wire-wrapping tools
a. Wrapping tools together with specific rotary bit and stationary sleeve
shall be
1. assigned to each wire gauge and terminal combination in use,
2. marked to show the size, for which it is calibrated.
b. The following power-driven wire-wrapping tools shall be used:
1. electrical tool with mains supply,
2. pneumatic tool, supplied with regulated, lubricated and filtered
air.
NOTE Figure A-1 shows examples of power-driven
wire-wrapping tools.
c. The power-driven wire-wrapping tools should be fitted with a “back-
force” device to prevent overwrapping defect.
d. Hand-powered or battery-powered wrapping tools shall not be used.
NOTE Refer to the tool manufacturer for selection of bit
and sleeve for each wire/terminal post diagonal
combination.
e. The tool and associated accessories shall be checked for cleanliness and
general satisfactory condition under up to ×10 magnification as follows:
1. The extremity of the bit is perfectly clean and smooth without
blockages or faults.
2. The sleeve does not have any sharp blockage in its neck, and
manual check ensures that the bit runs perfectly in the sleeve,
without any hard or rough points of contact.
f. The wire-wrapping tool shall not nick, ring, gouge, or scrape conductors,
or damage the terminal post in any way during its operation.
g. Any tool not conforming with the requirements 5.1.3.3a to 5.1.3.3f shall
be removed from the work-station for repair or replacement.
5.1.3.4 Unwrapping tools
a. The supplier shall provide an unwrapping tool compatible with the
terminal post diagonal which does not nick, ring, gouge, scrape or
damage the terminal post in any way.
NOTE 1 Figure A-3 shows examples of unwrapping tools.
NOTE 2 Wrapped connections can be detached from their
terminal posts, when necessary, by means of
special unwrapping tools.
NOTE 3 Manual unwrapping tools are preferred. They are
short tubular tools having an external spiral
groove and handle.
NOTE 4 A “left-hand” unwrapping tool is required to
unwrap a “right-hand” wrap connection
(clockwise wire rotation from base to top of
terminal), or vice versa for a “left-hand” wrap
connection.
b. Damaged tools shall be removed from the work-station for repair or
replacement.
5.1.3.5 Test monitoring equipment
a. Equipment for performance testing shall have the following
characteristics:
1. Connection 0 A - 10 A ammeter with current source
resistance
0 mV - 20 mV voltmeter
2. Stripping force Tensile testing machine
0 N - 100 N, accurate to ± 0,2 N
3. Visual inspection Binocular microscope, magnification × 7
minimum, with suitable light source
4. Microsectioning: Metallurgical microscope, magnification up
to × 400.
b. The equipment shall be capable of monitoring in the following range of
environmental conditions:
1. Temperature 15° C to 30° C, accurate to ± 1 °C
2. Humidity
RH 40 % to 70 %, accurate to ± 1 % RH
5.1.4 Configuration of process and workpiece
a. Materials, tools and techniques, which are planned to be used shall be
reviewed with respect to design needs, to ensure conformance to
customer requirements and as a means of identifying any pending
process qualification.
b. The review shall cover each separate manufacturing step including the
dimensions and metallurgical properties of the terminal post and wire.
NOTE Aim is that materials are proven to be acceptable
for the manufacture of wire-wrapped connections.
c. The choice of functional tools, particularly the type of power-driven
wire-wrapping tool and associated rotary wrapping bit and stationary
sleeve shall be demonstrated to be adequate to the wrapping process.
NOTE The quality of a wrapped connection depends
largely on the maintenance and adjusting of the
cutting, stripping and wrapping tools.
d. The supplier shall generate a dedicated process identification document
(PID) in conformance with the requirements in ECSS-Q-ST-70-38, listing
all used tools, material and the adjustment of the tools.
e. Work shall be managed and organized such that tool bits and sleeves
cannot be interchanged.
f. During handling and transportation, wrapped joints and their wires shall
not suffer from any mechanical or environmental constraint, likely to
cause deterioration.
5.1.5 Wire-wrap process certification
5.1.5.1 Initial certification of each wire-wrap combination
a. The capability of the wire-wrap tool shall be established to produce
acceptable wire-wrap connections for each combination of tool with
correct bit and sleeve, wire gauge and terminal post.
b. 30 sample wrap connections shall be prepared with a calibrated tool.
c. The certification test sequence shall be as follows:
1. Samples 1 to 30 Workmanship (see clause 5.5.1)
2. Samples 1 to 30 Connection resistance (see clause 5.4.4)
3. Samples 1 to 10 Stripping force (see clause 5.4.2)
4. Samples 11 to 20 Unwrapping test (see clause 5.4.3)
5. Samples 21 to 26 Gas-tightness test (see clause 5.4.5)
6. Samples 27 to 30 Metallography (see clause 5.4.6)
NOTE The successful completion of all above tests will
authorize spacecraft wire wrapping to commence
for the wrap combination.
5.1.5.2 Re-certification of each wire-wrap combination
a. Re-certification shall be carried out after the following occurrences:
1. When production wraps fail to conform with the requirements of
the daily process-control tests specified in clause 5.6.8.3.
2. At every 10 000 wire-wrap connections in a continuous
programme.
3. If production is interrupted for a period in excess of 12 months.
NOTE This is supposed to ensure reliability of the
joint, as the wire and terminals may degrade
during storage.
b. The re-certification test sequence shall be a repeat of the above clause
5.1.5.1, 30 sample wrap connections being prepared with a calibrated
tool.
5.1.6 Requirements for new combinations of wire-
wrap
5.1.6.1 General
a. Verification tests shall be conducted to establish confidence in the
reliability of wire-wrap combinations not detailed in Table 5-1.
b. The combination shall be considered verified following successful
completion of process certification tests in conformance with
requirements of clause 5.1.5 on 30 sample wraps before, and a further 30
sample wraps after temperature cycling and vibration testing detailed
below.
5.1.6.2 Temperature cycling
a. The test samples shall undergo 200 temperature cycles in a chamber from
room temperature to -55 °C, to +100 °C and back to room temperature
(22 ± 3)°C at a rate not exceeding 10 °C per minute.
b. Soak time at each temperature extreme shall be 15 minutes, such that the
duration of each cycle averaging one hour.
NOTE These conditions can be modified to conform with
the particular environmental qualification
conditions for the assembly being verified.
5.1.6.3 Vibration
a. After completion of the temperature cycling, the test samples shall be
subjected to vibration.
b. Test levels, frequencies and durations shall be agreed with the customer.
5.1.6.4 Documentation
a. The supplier shall document all conditions and operating procedures in
the PID format, see clause 5.1.4.
b. The supplier shall document all verification results in the RFA format,
subject to customer approval.
5.2 Material selection
5.2.1 Wire
5.2.1.1 General
a. Wire used for wrapped connections shall conform with ESCC Generic
Specification 3903.
NOTE Other approved national wire specification
intended for wire-wrapping may be agreed with
the customer.
b. The insulation type and wire finish shall be presented for approval by the
customer.
5.2.1.2 Conductor
a. The wire shall be a single solid round conductor.
b. Stranded conductors shall not be used.
c. Bending, stretching, or other cold working of the wire shall be avoided to
preclude damage to the base material or plating.
d. The conductor diameter shall be within the range 0,25 mm to 0,51 mm
nominal (30 AWG to 24 AWG), and from the following material:
1. soft-annealed, high-conductivity copper having an elongation at
fracture of not less than 15 %, for wire gauges 24 AWG and
26 AWG, or
2. high-strength, high-conductivity copper alloy with less than 2 %
strengthening elements, having an elongation at fracture of not less
than 7 %, for wire gauges 28 AWG and 30 AWG.
NOTE These materials are suitable for use within the
temperature range -55 °C to +100 °C.
e. Annealed copper shall not be continually operated for long periods
above 90 °C, owing to the likelihood that excessive wire stress relaxation
affects the reliability of the wrap connection.
f. The conductor shall be finished with smooth and uniform silver-plating.
NOTE The preferred average thickness of silver plating is
0,002 mm.
g. At the time of making the connection, the silver finish shall be free of
tarnish.
5.2.1.3 Wire insulation
a. The insulation shall consist of flexible polymer materials with low out-
gassing properties, in conformance with ECSS-Q-ST-70-02.
NOTE Recommended insulation materials include ETFE
(Tefzel), PFA (Perfluoroalkoxy), PVDF (Kynar),
and Kapton polyimide over extruded PTFE.
b. The insulation shall
1. not be bonded to the conductor;
2. be capable of being readily stripped from the conductor without
change to the physical characteristics of the wire;
3. be removed just prior to wrapping;
4. if pre-cut and stripped, the area be protected prior to use under
dry nitrogen.
c. There shall be no exposure of the conductor base material after insulation
stripping.
d. The conductor and its insulation shall be concentric such that the
minimum insulation wall thickness is not less than 70 % of the maximum
wall thickness.
e. The insulation shall have a wall thickness matching mechanical and
electrical stability, which is generally in excess of 35 % of the conductor
diameter.
NOTE Insulation wall thickness varies between wire
manufacturers; smaller values need substantiation
before acceptance.
f. The compatibility between the outer diameter of the insulated wire and
the tool bit shall be established.
g. The wire strip length shall be controlled to give the correct number of
turns of bare wire onto the terminal post, as specified in Table 5-2.
5.2.2 Terminal post
5.2.2.1 Material and plating
a. The material shall be selected from the following list:
1. grades of copper or nickel alloys, such as copper-zinc, phosphor
bronze,
2. copper-nickel-zinc,
3. beryllium-copper, nickel-copper (Monel), and
4. nickel-clad copper (Kulgrid).
b. The alloy hardness shall be within the range from 150 Vickers to 220
Vickers hardness.
c. Terminal posts shall be finished with 0,001 mm to 0,003 mm thickness of
gold plating over 0,001 mm minimum average thickness of copper or
nickel under-plating.
d. Silver under-plating shall not be used.
e. The surface finish shall be smooth and uniform.
5.2.2.2 Dimensions
a. The length of terminal post projecting from the mounting fixture shall
accommodate the required number of wrapped connections.
b. The number of wraps shall not exceed three per terminal.
NOTE The minimum wrapping length for each wire
gauge for one, two and three wrapped connections
on each terminal is shown in Figure 5-1.
c. Terminal posts shall have a solid cross section.
NOTE 1 Geometry and dimensions for each approved
terminal size are shown in Figure 5-2. Terminal
posts with a square cross section are preferred. The
rectangular (0,76 mm × 1,52 mm) post is included
to achieve better terminal packing density if
required for 24 AWG and 26 AWG wire, where the
more robust terminal is necessary.
NOTE 2 Referring to Figure 5-2, note that the tolerance on
diagonal C is more important than on A and B
dimensions, as posts are accommodated by round
holes in the tool bit.
d. The terminal posts shall be straight and free from bends and bows, which
can restrict the free entry of the post into the hole of the tool bit.
e. Bent terminals shall be rejected.
f. Tip configurations shall be in conformance with the following:
1. The tip of the terminal post terminates in a radius or bevel to
facilitate insertion into the wrapping tool.
2. Use flat apex of the bevel if the tip of the post terminates in a bevel,
3. The side of the flat does not exceed 0,38 mm on the 0,64 mm square
post geometry, or 0,50 mm on the 1,14 mm square post and on the
0,76 mm × 1,52 mm rectangular posts.
5.2.2.3 Stability
a. Terminal posts shall be durable enough to withstand being unwrapped
and re-wrapped and still conform with the test requirements in clause
5.4.
NOTE Annex A.2 describes the rework procedure.
b. Terminal posts shall be mounted and not capable of rotating during the
wrapping operation.
c. Boards or connectors with terminal posts for wrapping shall be handled
carefully in order to avoid damaging the sharp corners of the posts.
NOTE A practical means for avoid damaging is given in
Annex A.1.
Number of Minimum wrapping length (mm)
wrapped
connections 30 AWG 28 AWG 26 AWG 24 AWG
1 4,7 5,6 5,8 6,6
2 8,2 9,9 10,2 11,9
3 11,6 14,2 14,7 17,2
Figure 5-1: Minimum wrapping length on terminal post for each wire gauge
B
C
A
C
Burr 0,038 mm max. Radius 0,076 mm max.

Dimension (mm) Parallelism
(mm/mm)
A B C
0,64 nominal 0,64 nominal 0,90 nominal 0,005
0,56 minimum 0,56 minimum 0,83 minimum
1,14 nominal 1,14 nominal 1,68 nominal 0,005
1,07 minimum 1,07 minimum 1,50 minimum
0,76 nominal 1,52 nominal 1,78 nominal 0,005
0,69 minimum 1,45 minimum 1,60 minimum
Figure 5-2: Terminal post dimensions over minimum wrapping length for each
terminal size
5.2.2.4 Wire to terminal post combinations
a. Combinations of wire sizes to terminal post size shall be in conformance
with Table 5-1.
b. New combinations of wire and terminal post sizes shall be verified in
conformance with requirements from clause 5.1.6.
Table 5-1: Wire size to terminal post combinations
Wire size AWG
Terminal post size (nominal) 30 28 26 24
0,64 mm × 0,64 mm yes yes yes no
1,14 mm × 1,14 mm no no yes yes
0,76 mm × 1,52 mm no no yes Yes
5.3 Wire-wrap operation
5.3.1 Preparation for wire-wrapping
a. Insulation shall be removed by approved tools referred to in clause
5.1.3.2.
b. Stripping shall not expose conductor base metal.
c. After insulation removal, the remaining conductor insulation shall not
exhibit any damage such as nicks, cuts, crushing or charring.
d. Conductors with damaged insulation shall not be used.
NOTE Slight discoloration from thermal stripping is
acceptable.
e. The stripped conductor shall not be nicked, cut, scraped or otherwise
damaged.
NOTE Burnishing of the wire is allowed, provided the
conductor base metal is not exposed.
f. Conductors, which have been reduced in cross- section, shall not be used.
g. Damaged wires shall not be used.
5.3.2 Process and criteria
5.3.2.1 General
a. Wire-wrapped connections shall be produced in conformance with the
approved process identification document (PID) (as specified in
requirement 5.1.4d) using an approved tool type detailed in clause 5.1.3.
NOTE The step-by-step procedure is shown and
illustrated in Annex A.1.
b. Spacing between adjacent turns, the sum of all spaces within one wrap,
and the distances for positioning wraps on the terminal post shall be as
detailed in Figure 5-3.
NOTE This also gives the dimension limits for the
minimum number of turns required.
c. In case of necessary rework, the wrapped wire shall be uncoiled using an
approved hand tool (see clause 5.1.3.4), to preserve the corners of the
terminal post.
d. The tool shall be clean and without any blockages on the outside.
NOTE Details of the procedure and acceptable number of
reworks are given in Annex A.2.
e. Solder connections shall not be added to terminal posts supporting
wire-wrap connections.
5.3.2.2 Usage of wrap levels
a. The distribution of the wraps on the same post shall depend on the level
of wiring.
NOTE Terminal post length is designed to receive a
maximum of three levels of wrap joint.
b. The first connection onto the terminal shall be at level Zl.
NOTE 1 Levels Zl and Z2 (see Figure 5-3) are generally used
for point-to-point interconnection.
NOTE 2 Level Z3 is generally reserved for modification,
doubling of wire gauge between two points.
c. Wraps that extend above level Z3 onto the bevelled apex portion of the
post shall be removed and replaced.
NOTE Lower wraps may extend into the Z3 level if it is
open and not reserved for future wiring.
d. Wire-wrap level and wire routing shall be identified on the engineering
drawing.
Useful length of terminal
d
e1 e2
c
d
e3 e4 E d
S
Z1 Level Z2 Level Z3 Level
Terminal
base zone
E = Maximum single spacing within one wrap;  Ε ≤ c/2
S = Sum of the spaces within one wrap; S ≤ c
S = e L e L e L e
1 2 3 4
c = Conductor diameter
d = Distance for positioning the wrap within the useful length of the terminal post;
d ≥ 0 (or no overlap allowed):
 between base of post and the conductor insulation,
 between two adjacent wrap connections,
 relative to the limits of the terminal, not including the tip region.
e = Space between adjacent turns - exclusive of gaps on the first and last half turns.

Figure 5-3: Position and regularity of wrap connection
5.3.3 Number of turns on terminal post
a. The number of turns of uninsulated conductor shall be counted from the
reference corner.
NOTE The reference corner is the first corner of contact if
the insulation stops before the central axis of the
post, or the second corner if the insulation crosses
the central axis of the post (see Figure 1-1).
b. There shall be no overlap of turns to the last locked point.
NOTE 1 The last locked point is the last terminal post
corner.
c. The end tail shall not extend away from the outside diameter of the
conductor on the post by more than the diameter of the conductor.
d. The minimum number of turns of uninsulated conductor and insulated
wire to be wrapped for each wire gauge shall be as specified in Table 5-2.
NOTE This ensures that the gas-tight area of the
connection results in a larger cross section than
that of the wire used.
Table 5-2: Minimum number of wire turns on terminal post
Wire size
Minimum number of turns
AWG Nominal diameter
(mm) (conductor + insulated wire)
30 0,25 7 + ¾
28 0,32 7 + ¾
26 0,40 6 + ¾
24 0,51 5 + ¾
5.3.4 Wire routing
a. Wire routing around and between terminal posts shall be such that wires
do not press against the corners of posts with sufficient force to cut the
insulation.
b. Wire with insulation, which has been cut, shall be removed and replaced.
NOTE Wires can be re-routed to correct a tight wire
condition or relieve a wire density problem,
provided the wrap connection is not disturbed.
c. Disturbed joints shall be rejected and replaced.
d. Wire shall not be routed above the terminal posts.
e. Long lengths of interconnect wire shall be bonded or tied down to the
module at 50 mm to 75 mm intervals to reduce resonance in the wire
during vibration.
5.3.5 Rework
a. When replacement connections are made in conformance with
requirement 5.3.2.1c, the wire routing shall follow the original route.
b. If only two levels of wrap on the terminal post are occupied, the Z3 level
shall be used as an alternative to rework the lower level wrap joints.
c. A wire-wrap rework log shall be established and maintained during
manufacture and test for each flight assembly.
d. The log shall contain the positions of the reworked wraps and the
number of reworks on every terminal post.
5.4 Test methods
5.4.1 General
a. The following test methods shall be used to verify the quality of
wire-wrap connections:
1. Tool calibration: in conformance with requirements in clause 5.6.5.
2. Wire-wrap process certification: in conformance with requirements
in clause 5.1.5.
3. Process control: in conformance with requirements in clause
5.6.8.3.
NOTE The number of wire-wraps to be tested, together
with the test methods, is detailed in the following
clauses.
5.4.2 Stripping force
a. Stripping force test shall be performed to determine adequate tightness of
the wire around the terminal post.
b. A completed wire-wrap connection with the minimum number of turns
listed in Ta
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