Spacecraft Harness Fabrication Process PDF

SPACECRAFT HARNESS FABRICATION PROCESS 1 M.Kamalavathi Head- HES January 2025 Committed To Total Quality And Zero Defect In Space Systems And Services  Spacecraft Harness assembl...

SPACECRAFT HARNESS FABRICATION PROCESS 1 M.Kamalavathi Head- HES January 2025 Committed To Total Quality And Zero Defect In Space Systems And Services  Spacecraft Harness assembly QA log registers 2WPT, Continuity- Design cross continuity EID data cards, Testing Inputs worksheets & DOR Operators training & Ceritifcatation Parts Connectors & contacts Inspection Harness audit certificate Lenses, retention Butt splices and ground Materials Wires and cables Non conformance lugs lacing thread, cable ties, potting compound, Tools & Accessories Ecco bond, Guidelines, Alerts, validations calibration Recommendations Quality means doing it right when no one is looking- Henry Ford  Spacecraft Harness(EDS) 3  Electrical Integration activity involves interconnecting different subsystems electrically using specifically designed harness in a systematic way.  Based on design consideration, all fabrication works, handling, testing, formation of harness is with in the frame work so that meets the requirements and acceptable as flight worthy harness. ❑ Each & every EDS is unique. It Provide all the necessary interconnections between Subsystems ❑ Ensure the interconnections which doesn’t degrade the subsystem performance ❑ Meet all the environmental specifications ❑ Easiness in panel assembly & disassembly ❑ Minimum EMI problems ❑ Manage the complex connectivity , maintains the interconnection database & clear identification of harness & its distribution schemes ❑ Adhere to the standards of EDS & ensure safe-to-mate for flight packages ❑ Facilitate testing of sub-assemblies during disassembled mode and have minimum possible size, length and weight. ❑ Have minimum breaks between source and destination ❑ Care must be taken to plan so that the harness allows for easy assembly, removal & testing of all system assemblies and harnesses  Standards 4 ❑ ISRO-PAX-300 : Workmanship standards for fabrication electronic packages ❑ ISRO-PAS-100: Non conformance control requirements ❑ ECSS-Q-ST-70-26C : Crimping of high reliability electrical interconnections ❑ NASA-STD-8739.4 : Crimping, interconnecting cables, harness and wiring  TOPICS 5  6 Spacecraft harness flow chart Check / Double check / Recheck  8 CHAPTER-1 Connector contacts crimping Crimp Validation “Get What You Expect By How You Inspect”  Different type of processes 9  Crimping of:  Standard density and HDD contacts  Butt splice contacts  Ground lug terminals  RF connectors  1553 connectors & Inline splice  Soldering of:  1553 connectors  Shield spiral splice, hook joint, lap joint, lash joint etc,.  Sleeve shrinking of different contacts and terminals  Insertion & Extraction of contacts  Rework of contacts in connector  Retention checks of contacts  Lacing of harness  Connector types 10 Standard density type Plug RF connector Socket Plug Jack High density type Micro D type Plug Plug Socket Socket Circular type 1553 type Plug Plug Socket Socket  Connectors Pin Variants 11 D-Sub Standard density & HDD connector 9,15,25,50 & 78 pin D-BAS Circular connector 3,7,12,19,27,37 and 61-Deuscth make  Micro D Connector- 3,9,15,21,25,31,37,51 and 100  RF connectors  1553 type  Visual photos of different types connectors 12 Standard density High Density Micro D Circular Connector RF Connector 1553 Connector  Parts of a connector 13  Shell- Brass -0.7 micron gold over 1 micron copper(ESCC)  Insulator-Diallylphthalate/thermoplastic type PCT (out gassing :TML:1%,CVCM:0.1%)  Contacts-Copper alloy-1.27 microns gold over 1 micron copper(ESCC)  Contacts types and sizes 14 1. Standard density contacts ◼ 20-26 Size ◼ 20-20 Size 2. HDD(high density D-Sub) ◼ 22D Size 3. Circular(D-BAS circular) ◼ 12 Size ◼ 16 Size ◼ 20 Size  Terminals types and sizes 15 1. Butt splice terminals ◼ 26-22 ◼ 24-26 2. Ground lug terminals(barrel and stud) 26-22(Panduit make) 3. Tubular terminal S8-14R-Q (Panduit make)  Where crimping is used? 16  Crimping shall be used where weight & space are major criteria in system design  Crimping shall be used when hot soldering iron could cause hazards  Often it is used in spacecraft harness.  For panel level harness  For wiring on structure  For wiring on payloads  For wiring on solar panels  CRIMPING 17 Definition: It is a process of joining contact & conductor wire by mechanical pressure using specially calibrated tool. Crimping shall be used where weight & space are major criteria in system design  CRIMPING 18 Why?  No heat, No flux, No residues, less time, Repeatability  High density of contacts can be achieved  Low contact resistance due to true metal to metal contact  Wiring error correction by removal & reinsertion of contacts  Consistency - electrical & mechanical characteristics are reproducible  Replaceability - damaged contacts can be easily replaceable  Quality assurance by controlling tool quality How?  You will use a crimping tool When? ❑ Might need different lengths or extension wires than included in your work sheet ❑ Soldering is not possible  What is the advantage of crimping over soldering 19 Sl Crimping Soldering no 1 High density of contacts can be achieved Density is less 2 No external heat applied during crimping Heat is required 3 No usage of flux, no residue of flux & its Flux is required corrosion 4 Crimping requires less time compare to other More time type of joining 5 Low contact resistance due to true metal to Same metal contact 6 Wiring error correction by removal & Correction is difficult reinsertion of contacts 7 Consistency - electrical & mechanical Not reproducible characteristics are reproducible 8 Replacbility - damaged contacts can be easily Rework is difficult and cannot achieve replaceable good joint  CRIMPING - Gather tools 20 You will need:  Crimping tool MIL-22520/2-01  Wire strippers  Cutters - hard and soft type  Tape to measure  Crimping tool 21 PURPOSE - To achieve high quality crimp joint with uniform compression FEATURES MIL QUALITY - Tool conforms to the MIL standard MIL-T-22520/2-01, MIL-T-22520/1-01 PLIER TYPE TOOL - Containing set of four indents, squeezes the contact when the handles are closed. RATCHET CONTROL ARRANGEMENT - To prevent its opening before completing the crimping cycle. LOCATOR - To hold the contact in correct position between the indents SELECTOR - Eight different depth can be selected by adjusting the selector knob based on contact size & wire gauge  Materials 22 Wires , Cables and Parts  O,OS,TP,TPS,TTS,TTDS,TPDS,SPEC-55 – Ox, OxD  Male pin plug:20,22,20-26  Female pin socket;20,22,20-26 Connector types  9,15,25,37,50,78-pins  Micro-D(9,15,21,25,37,51)(LCP) Make  ITT, C&K Souriou, Amp, Amphenol, Glenair  Crimping tools, accessories, Procedure 23  Checking the calibration of the crimping tool 24 - Set the selector knob at position 8 - Press the lever of the crimping tool to fully closed position. - Insert "go" gauge, between the indentors. (It should pass freely) - Insert the "no-go" gauge between the indenters. (It should not pass) Note: Do not crimp the go & no-go gauging tool  Crimping tools 25 PURPOSE - To achieve high quality crimp joint with uniform compression FEATURES MIL QUALITY - Tool conforms to the MIL standard MIL-T-22520/2-01, MIL-T-22520/1-01 PLIER TYPE TOOL - Containing set of four indents, squeezes the contact when the handles are closed. RATCHET CONTROL ARRANGEMENT - To prevent its opening before completing the crimping cycle. LOCATOR - To hold the contact in correct position between the indents SELECTOR - Eight different depth can be selected by adjusting the selector knob based on contact size & wire gauge  Hand crimp tools 26 Pliers Type  Very hard to get repeatable crimp results especially with different operators  Hand strength of user effects crimp quality  Can not predict longevity of the crimp  Best for emergency repairs or when the user can tolerate short crimp life and expense & downtime of potential multiple repairs due to failing crimps Ratchet type tool  Repeatable crimp results especially with different operators.  The crimp quality is not effected by the hand strength of the operator.  Predictable long lasting crimp life.  Crimping Procedure 27 Wire cutting Insulation striping After stripping  CRIMPING Prepare the cable 28  Ensure you have work instruction and checklist or any documents containing the details of your activity and Measure the length of cable you need  Ensure You have designer requirement/input for commencing the work (NO ORAL COMMUNICATION)  Make sure to leave yourself 1 or 2’ of extra length, incase of a mistake  IF your cable needs to be a more exact length, be very accurate; once the pins have been locked into position, they can not be removed  CRIMPING – Trimming and Stripping 29 INSULATION STRIPPING - Remove 5 mm length of wire insulation by mechanical stripper or thermal stripper CHECK FOR CORRECT LOCATOR M22520-2-08 D-type Check selector number - as per contact size & wire gauges Insert the contact into jaws of tool with barrel facing up Insert bare wire into the open end of the contact Operate the tool - squeeze the lever of the tool (tool will not release the contact until the full crimping cycle has been performed) Remove the crimped assembly/contact from the tool  CRIMPING Step 1 30 We will now begin making the connector ❑ Become familiar with your crimper  Make sure you know how to squeeze the handles until the crimper unlocks  Use the gauge guide (shown at right)to determine which site to use for your gauge of wire  In our case, selector nos. are used depend on the wire gauge.  CRIMPING Step 2 31  The crimper holds the pin in place during crimping  Locate the spring loaded clamp below the jaw of the crimper  Raise the clamp with your finger, as shown  Choose a right pin for connector  Place the pin into the open slot on the crimper while the clamp is raised - The male or female end goes in first - the pin cradle should face up or open upward ❑ The pin should move forward until the front of the pin cradle is against the spring loaded clamp  CRIMPING Step 3 32  Release the spring loaded clamp  This will lock the pin in position  The pin is designed to fit into this crimper -If your pin is crooked, or if the clamp does not clamp down properly, simply lift up the clamp and try again ❑ Check indentation depth  The wire must be positioned using these teeth as guides -inner set of teeth should be over exposed metal wire -outer set of teeth should be over insulation  Using the guides in the first part of step 5,place the wire in pin cradle, as shown  CRIMPING Step 4 33  Squeeze the crimpers handles to secure the wire into the pin  -Make sure to hold the wire steady so that does not move while crimping  -Squeeze the handles until you feel them release  Remove the wire from the crimper - Push on the bottom of the clamp to release the pin - Once you have reached this state, you can not separate the wire from the pin without cutting the wire  CRIMPING Step 5 34  Remove the wire from the crimper - Push on the bottom of the clamp to release the pin - Once you have reached this state, you can not separate the wire from the pin without cutting the wire  CRIMPING Step 6 35  Place the wires in the crimping housing  The wires must go in order by the work sheets provided by the Integration.  Line up the wires into a connector housing, Make sure the locking tab on the pin cradle is facing up, as shown  Slide the pin into the housing, as shown ,until the pin is locked into position, do not force the wire, the pin might make a clicking sound when it has locked into position  To test if your pin is locked in to the crimp housing, wire, gently tug on the wire  SELF INSPECTION BY OPERATOR 36 Check the wire strands in the inspection hole of the crimp barrel Insulation clearance shall be 0.5 to 1.0mm Contact insertion - place the tool over the wire - Insert the crimped contact along with the tool into the connector. - Withdraw the tool Contacts extraction - place the tool on the wire - slide the tool into the connector until it stops - Remove the contact along with the wire  Quality control requirements 37 SELF INSPECTION OF CONTACTS/WIRES/CONNECTORS PRIOR TO CRIMPING BY OPERATOR FOLLOWING DEFECTS FORM THE REJECTION CRITERIA. - Any evidence of spotting or film formation (eg: Dark spots, scratches, lines etc.) - Damaged or improperly processed crimp (dents, bends) - Cracking or chipping of contact - Plating defect ( peeling, chipping and voids) - Improper or damaged marking - Discolouration - Contamination  Inspection after crimping 38 Ensure following defects are not seen :  Nick, cut or damage of the wire strands  Reduction in cross section of the wire  Embedding of insulation into the contact barrel (a clearance of 0.5 t0 1 mm shall be maintained between the crimp barrel and the insulation edge).  Damaged contact showing improper or over crimping.  Excess deformation of wire strands.  Voids in wire strands bundle, showing under crimping.  Visibility of wire strands through the inspection hole. 39  SLEEVING 40  Kynar sleeve is used for crimping contacts and Polyolefin heat-shrinkable sleeve is used for butt splice contact/crimp/solder joints/ground lugs  This will cause the sleeveing to have a tight mechanical grip on the item it covers.  Sleeving 41  Insulation sleeves: Conforming to MIL-I-23053  Purpose: Insulation sleeves shall be used for mechanical and electrical protection of the solder joints, wires and leads, and to protect the wire harness against abrasion  Type of material used: Polyolefin (pvf2) Polyvinyledene fluoride (KYNAR) ❑ Procedure - Select the proper size of the sleeve. - Install the sleeve prior to attachment of the conductors. - Avoid interference during soldering/crimping operation. - Perform soldering/crimping operation. - Clean the joint formed thoroughly. - Slip the insulation sleeves over the solder/crimp joint. - Shrunk the sleeve using hot air blower - Ensure 100% tight shrinking with out air gaps & damages to the insulation  Features of insulation tubing 42 - Sleeves shall be transparent - Shall impart high mechanical strength to the solder joint. - Sleeves shall not react with chemicals used for fabrication - Operating temperature range of the sleeves shall be –50 0 c to + 250 0 c - Sleeves shall have 50% shrinking ratio. - Final diameter of the selected sleeve shall be such that the sleeve tightly grips the members of the solder joint/crimp joint. - The length of the sleeve shall be extending beyond the stripped portion of the attached conductor, up to a distance equal to or greater than the tube external diameter.  Steps for shrinking 43 STEP 1 Select the proper size of heat shrink tubing. In order to get a secure fit, be sure that the tubing's recovered diameter (the diameter after shrinking) is smaller than the diameter of the area you're going to insulate. At the same time, the- tubing's expanded diameter (the diameter before shrinking) needs to be large enough to easily fit over the area to be insulated, as well as any connectors attached to it. STEP 2 Cut the heat shrink tubing to a usable length, and be sure to allow for a minimum 1/4" overlap over any existing insulation or contacts. Keep in mind that tubing also shrinks lengthwise…typically 5-7% during the shrinking process. STEP 3 Slide the cut tubing over the object that you're covering, if you'll be splicing, slide the tubing over the center of the splice, and allow for equal overlap on both sides.  Steps for shrinking 44 STEP 4 Before shrinking, check your tubing's specifications for the recommended heating temperature. Any commercial heat gun or heat shrink oven can be used to shrink the tubing. Since uncontrolled heat can cause uneven shrinkage, physical damage and insulation failure, the use of open flame is not recommended. STEP 5 If you're covering a long length of cable with tubing, begin shrinking at one end, and gradually work your way down to the other. To ensure that the tubing shrinks evenly and without air bubbles, rotate the object as you're applying heat. STEP 6 Evenly apply heat over the length and around the diameter of the tubing, until it is uniformly shrunken and conforms to the shape of the cable, hose, or splice that it's covering. Immediately remove the heat source, and allow the tubing to cool slowly before you apply physical stress to it. STEP 7 Avoid overheating the heat shrink tubing, because it will become brittle and/or charred.  Contact retention checks 45  Select the tool for retention checking  Fix the connector on a stand  Select the tip for retention testing  Hold the tool over the pin to be tested  Apply force to check retention  With draw the tool Note: -: a backward movement of the contact indicates improper insertion Precaution : - do not push the tool unless the tool is exactly the axis of the contact.  46 MATERIAL SELECTION  Wires  Cables  Contacts  Connectors  Sleeves  Cable ties  Lacing thread  SOLDER sn63 pb37  RMA flux  IPA electronic grade  Lint free cloth  Silver coated copper wires  Types of wires/Cables 47 Ordinary -O Ordinary shield-OS Twisted pair-TP Twisted pair shield-TPS Twisted three core with shield-TTS SPEC 55 LVDS 1553 RF cables  Images of Wires and Cables 48 ORDINARY ORDINARY TWISTED PAIR SPEC 55 SHIELD SHIELD LVDS CABLE 1553 CABLES RF CABLE RF CABLE  Wires/Connector selection / MIL specifications numbers 49  Verification of SIV(Store issuing voucher)  Wires and cables shall be drawn from bonded stores  Verify the batch code and expiry date of each type  Verify the connector manufacturer/type/batch code and date code along with expiry date  MIL-W-81381  MIL-C-27500  MIL-C-17  SPEC –55  Spec-55 50 Spec 55 MIL-W-22759 wire is insulated with modified radiation cross-linked ETFE polymer. It has a temperature rating of -65°C to 200°C continuous, and combines the easy handling of a flexible wire with excellent scrape abrasion and cut through characteristics, Resistant to electrical arc tracking in wet or dry conditions Single or dual wall constructions Small size, ultra light weight Exceptional chemical resistance not susceptible to UV and moisture degradation. Silver or nickel plated conductor) -65°C to +200°C Voltage rating 600 V  Kapton /polymide wires 51  The ability of Kapton is it has excellent physical, electrical, and mechanical properties over a wide temperature range  A flame-resistant material, Kapton film is a laminate of polyimide and FEP which is heat-sealed to itself above the FEP( Fluorinated Ethylene Propylene) melt temperature.  Properties: Physical and thermal : Continues use temperature is 200° C 10minutes endurance temperature is 500° C Electrical characteristic: Dielectric constant, dissipation factor and volume resistivity(ohms-cm) is good Environmental characteristics: It is resistance to …. Excellent Cut through ,Ultraviolet radiation and Electrical-mechanical stress  MIL-STD-1553 52 MIL-STD-1553 is a military standard published by the United States Department of Defense. That defines the mechanical, electrical, and functional characteristics of a serial data bus. It was originally designed for use with Military avionics.  LVDS 53 Low-Voltage Differential Signaling (LVDS) is a new technology addressing the needs of today’s high performance data transmission applications. LVDS delivers high data rates while consuming significantly less power Other benefits, which include: Low-voltage power supply compatibility Low noise generation High noise rejection Robust transmission signals Ability to be integrated into system level ICs 54 Tools used 54 Sl. No Tool name Part no Feature Make Photograph Circular M 22520/1-01 For crimping Daniels 1 connector Circular Manufacturing contact crimping connector corporation tool contact s Contact M 22520/2-01 20 size & 20- Daniels 2 crimping tool 22 size Manufacturing contacts corporation crimping tool Wire stripper MIL-81044 16-26 AWG Ideal strip master 3 wire stripping Sl. No Tool name Part no Feature Make Photograph MAGNIFICATION AIDS Different sizes For Mantismag 29 2X - 4X AND 10 X magnification Vision engineering Magnification: 2.5x (5x) Working Distance: 85 mm Field of View: 60 mm. Retention check tool HT210-22 Contact Daniels 30 Retention check Manufacturing corporation  Sleeve shrinking of contact 56 2mm  Acceptable criteria 57 Sl.No. Visual photograph Observations 1 Good insulation removal-1 Insulation has been trimmed neatly, no signs of pinching, pulling, fraying, discoloration, charring or burning. Acceptable 2 Insulation clearance 1. Insulation clearance is ~1D where D is the wire diameter(1) 2. Crimp area shall be middle (2) 3. Inspection window shall have conductor visibility (3) Insulation clearance is correct 3 Insulation clearance is 1D Acceptable  Reject Criteria(cont.) 58 Sl.No. Visual photograph Observations Strand damage Strand cut marks or scratches not allowed 1 Number of strand cut allowed is ONE Not Acceptable 2 Bird caging Wire strand separation is not allowed. Not Acceptable Insulation removal -2 Ragged pieces of insulation. Deep tool 3 mark on insulation, insulation thickness reduced more than 20% not allowed. Not Acceptable 4 Insulation burning Melted insulation not allowed Not Acceptable  Reject Criteria(cont.) 59 Sl.No. Visual photograph Observations Insulation damage Improper stripping of insulation 5 Nick in insulation not allowed Not Acceptable Insulation embedment Insulation is embedded in to the contact barrel. 6 Not acceptable Insulation clearance is more Insulation clearance is more the 1 D Not Acceptable 7 Improper insulation clearance Unequal insulation clearance for double wire crimping 8 Not acceptable  Reject Criteria(cont.) 60 Sl.No Visual photograph Observations Insulation clearance is less Single wire crimping: Insulation enters into the barrel. Double wire crimping: One wire insulation 9 enters barrel and other one, insulation clearance is visible. Not Acceptable Conductor not visible through inspection Window 10 Not Acceptable Crimp indentation mark is too close to inspection window 11 Crimp is not at the centre of the barrel Not Acceptable (major defect) Strands twisting 12 Conductor strands are twisted after stripping Not Acceptable  Reject Criteria(cont.) 61 Sl.No. Visual photograph Observations Conductor strand outside the crimp area Conductor strand is seen outside the crimp barrel/area. 13 Not Acceptable Crimp indentation at contact edge Crimp indentation is made at the barrel edge not at the centre 14 Not Acceptable Contact barrel crack 15 Crack in contact barrel Not Acceptable(major defect) 16 Fill wire extends beyond the insulation of the primary wire. Not Acceptable  Rework methods 62  Cut and remove the contacts As per the requirement from subsystem and integration As per the requirement from project Due do workmanship error As per recommended committee  Swapping of contacts As per the requirement from subsystem and integration As per the requirement from project Due to error in EID As per committee recommendation  Records updation 63  Ensure entries to make in work sheet or DOR(Daily operation record)by EID Engineer  Reworks (process related) are to be entered in work sheet/DOR by operator and approval from QC 64 Chapter-2 Butt splice contact crimping  Butt splice contact dimensions 65  Contact size:26-24 0.91 mm-ID 8.70 mm  Tools used 66 Tool name Part no Feature Make Photograph Butt splice 69363 Thermal joints Amp crimping tool and extension of wires. Wire stripper MIL-81044 16-26 AWG Ideal strip wire stripping master  Tool/slot used for different gauges using Butt splice 67 Tool part no: 69363 Contact size: 26-24 Sl.No Wire gauges Slot used 1 2 x 28 AWG or 22-20 28 fold back 2 26 AWG 24-26 3 24 AWG 24-26 4 22 AWG 22-20  Combination of wire crimping using butt splice 68 Sl.No. Visual inspection one end Other end Optical photograph 1 Wire Gauge:28 No. Of strands:07 2x 28 Outer Insulation: kapton 26 No. of core :single 2 28 fold back Wire Gauge:26 No. Of strands:19 26 Outer Insulation: kapton No. of core :single 3 Wire Gauge:24 No. Of strands:19 24 26 Outer Insulation: kapton No. of core :single 4 Wire Gauge:22 No. Of strands:19 22 26 Outer Insulation: kapton No. of core :single 5 Wire Gauge:22 and 24 24 22 Same as above  Crimped Butt splice contact 69 Bell mouth visibility or appearance at the edge and near the inspection window 0.5 to 1 mm Conductor strands must visible at inspection window  Sleeve shrinking of Butt splice 70 30 mm 25 mm Sl.No Process Type of Sleeve Diameter of the Length of the sleeve in mm sleeve in mm 1. Butt in Polyolefin Inner 1.6 mm 30 mm splice outer 2.4 mm 25 mm  Accept Criteria 71 Sl.N Visual photograph Observations o. Crimp splice -Butt splice joint 1 Ends of the wire visible though inspection windows Wire insulation is flush with end of splice Crimp is centered properly and formed to retain wires 2 The contact has been deformed only by tool Indenters. Indents are symmetrical and centered on the crimp barrel. No exposed base metal or other damage. Wire strand ends are visible. Proper insulation spacing  Reject Criteria 72 Sl.No. Visual photograph Observation 1 Insulation extends into the crimp Barrel Crimp indent is not cantered (It is at the end) Wire ends are not visible through Inspection window Insulation gap is more Not acceptable 2 Sleeve damage Wire strands pierced through the sleeve Not acceptable Wire strands extend out of inspection window. 3 Not acceptable 73 Chapter-3 Ring terminal crimping  Tools used 74 Tool name Part no Feature Make Photograph Lug crimping tool CT-1570 For 10-22 AWG wire Panduit lug crimping Wire stripper MIL-81044 16-26 AWG wire Ideal strip stripping master  Ring terminal size 75 Ring terminals size-26-22 and stud size Ring tongue design assures a secure connection in high vibration applications Brazed seam protects terminal barrel from Internal barrel splitting during the serrations assure crimp process good wire contact and maximum tensile strength  Ring terminal crimping 76 Finished Crimp Finished Crimp Acceptable crimped-Micro section view Rejected  Slot used 77  Sleeve shrinking of ring terminal 78 12 mm 10 mm Sl.No Process Type of Sleeve Diameter of the Length of the sleeve in mm sleeve in mm 1. Ground Polyolef Inner 1.6 mm 10mm Lug M3 in outer 2.4 mm 12 mm  Various wire gauge used for ring terminal crimping 79 Tool part No: CT-1570 and slot 22-18 Sl.No. Stud size/ Wire AWG used Optical Photograph barrel size 2x26 1 26 fold back 2 26-22 24 3 22 4  Accept/Reject Criteria 80 Sl.No. Visual photograph Observations 1 acceptable 2 Excess length of strands Not acceptable 3 Strands not visible at inspection hole Not acceptable 4 Contact bend in stud area Not acceptable  Specification as per manufacture catalog 81 82 Chapter-4 Shield termination process  Materials required 83  Shielded Cables  Solder Sn63  Flux –RMA  Isopropyl Alcohol-(IPA- electronic grade)  Lint free cloth  Soft Brush etc,.  Shield termination/splicing 84 Lap joint Spiral splice solder joint Shield termination with screw lock assembly  Shield termination process 85 Steps involved Procedure/Method Optical View Removal of ✓ Remove the Kapton outer Kapton outer jacket insulation using Hot jacket(D-SUB) tweezers (thermal stripper). The wire/cable 45mm length for 9/15/25 are LVDS – pins D-Sub Connectors OS/TPS/TPDS 55mm length for 37/50 pins D-Sub connectors Depending on the 65mm length for 78pin D-Sub connector type connectors ✓ Ensure inner core insulation is NOT damaged, cracked, discolored & charred. ✓ Ensure No inner conductor shall expose ✓ Ensure No over twisting of shield braid & cuts  Shield termination process cont.. 86 Steps involved Procedure/ Method Optical view ✓ Refer bending direction as per For 900 Bend D- work sheet data provided by AIT Sub formation For 9/15 pin connector, Maximum shield extraction 55±5mm length insulation length depends on the removal connector For 25pin connector, 95±5mm length insulation removal For 37/50/78 pin connector, 120±5mm length insulation removal or suitable length based on access.  Shield termination process cont.. 87 Steps involved Procedure/Method Optical view For LVDS Cables Shield extraction length for LVDS type is maximum 40mm. Or As per the designers requirement along with the concerned of SRG Utmost care shall be taken during wiring  Shield termination process cont.. 88 Steps involved Procedure/Method Optical view Separation of shield Open the shield braid carefully braid and inner core wires using wooden tooth pick or Teflon rod Note: Mandatory points Ensure no strands of braid are cut. Separate the inner core wire or Folding of inner core wires shall not be less Fold the shield braid backwards as than 1D shown in figure Ensure NO Trim the excess length extended wrinkles & cracks on the wire. towards the wire. Length 25 to 30mm  Shield termination process cont.. 89 Steps involved Procedure/Method Optical view Preparation of shield ✓ Use thermal shunt for non for soldering Note: wicking of strands Selection of Ground lug Trim the shield maintaining the Connecting wire required length of 25 to 30 22 gauge shall be mm. used for all types of Tinning of solder able area 8 cables. to10 mm using Sn 63 solder Selection of ground lug For OS 24 and 26 connecting wire-24AWG for gauge use only grounding 24AWG Strip the insulation of 8 mm for grounding wire. Un-tinned portion shall be 1d 8 to 10 mm to 2d or 1 to 1.5mm as applicable Lap joint as per fig shown for all the shields OS/TPS/TPDS  Shield termination process cont.. Steps involved Procedure/Method Optical view 90 Ensure solder fillet is uniform, without voids, pit and discontinuities on shield after soldering. ✓ Ensure NO solder flow in un- tinned areas of wire ✓ Butting wire for soldering shall be 5 to 6mm on shield for 15 to 20 mm soldering Insulation clearance from shield edge shall be 1 5 to 10 mm to1.5mm Insulation overlap is NOT acceptable on shield  Shield termination process cont.. 91 Steps involved Procedure/Method Optical view Sleeve Shrinking Preferred outer sleeve length Inner sleeve 8 to 10 mm using polyolefin sleeve is 35 to 45mm 8 to 10mm for inner core Shrink the sleeve uniformly without air gap, discoloration Outer sleeve 35 to 45 mm & cuts  Shield termination process 92 Shield extraction length followed currently across all projects  9 to 25 pin- 45mm  37 to 50 pin – 55mm  78 pin– 65mm Shield fold back length /for lap joint preparation – 20mm maximum Lap joint extension wire 22/24/26AWG for spiral splicing – 50 to 70mm+/-10mm is acceptable.(In RS2A-35mm) Spiral splices up to 10 lines(26AWG- 1 splice joint)  Refer guidelines(quick reference table) Grounding lug wire extension(24AWG) – 220 to 250mm maximum followed across all projects. However 150 mm is acceptable.  Spiral Splice Solder Joint 93 Materials required 1. Wires/Cables 2. Binding wire- Silver coated copper wire 3. Solder - Sn 63 4. Flux – RMA 5. Isopropyl alcohol 6. Brush 7. Polyolefin Heat shrinkable sleeves  Procedure for making spiral splice solder joint 94  Insulation stripping using mechanical/thermal stripper.  Stripping length depend on the number of wires to be spliced  Conductor tinning using Sn63 solder by leaving insulation clearance 0.5 to 1 mm.  Bind the stripped wires together using silver coated copper wire 26/24AWG (spiral).  Apply minimum flux RMA and Solder uniform over the splice joint.  Ensure no solder is entered towards wire insulation.  Splice solder joint cleaning using IPA  Check for solder joint quality shall be free from flux/IPA residues.  Splice solder joint sleeve shrinking using polyolefin sleeve  QC requirements for spiral splice solder joint inspection 95  Soldered joint shall be bright and shiny.  Uniform coverage on the spiral area.  Contour of conductor shall be visible -concave fillet.  Untinned portion shall be 1 to 2d (mandatory).  Sleeve tip shall be sealed after shrinking without air gap in hot condition.  Sleeves shall be free from air gap, discoloration, cuts etc,.  Selection of wires for Spiral splice joint 96  Maximum number of wires shall be 12 for splicing 26 gauge  Maximum number of wires shall be 10 for splicing 24 gauge  Maximum number of wires shall be 08 for splicing 22 & 20 gauge  Number of turns/splice: Minimum 5 to 10 turns depending on the wire gauges.  Insulation clearance :1D or Number of wires together in a bundle  Heat Shrinkable sleeve on spiral splice solder joint is 35±5mm.  Binding silver coated wire should be 24 or 26AWG  Sleeve shrinking 97 30 to 40 mm 8 to 10 mm 35 to 45 mm Sl.No Process Type of Sleeve Diameter of the Length of the sleeve in mm sleeve in mm 1. Splicing Polyolefin Depend on the 30 to 40 mm No.of wires/Gauge 2 Lap joint Polyolefin Inner 1.2 mm and 1.6 8 to 10 mm mm outer 2.4 mm 35 to 45 mm  Guidelines for sleeve requirement - shielded cables 98 Sl. Cable type Wire Gauge Polyolefin sleeves Polyolefin sleeves No AWG diameter in mm diameter in mm ( inner sleeve) (outer sleeve) 1 OS 26/24 1.2 mm 2.4 mm 2 OS 22/20 1.6 mm 2.4 mm 3 TPS 26/24 1.2 mm 3.2 mm 4 TPS 22/20 1.6 mm 3.2 mm 5 TTS 26/24 1.2 mm 3.2 mm 6 TPDS 22 1.6 mm 4.7 mm  Guidelines for sleeve requirement for Contacts 99 Sl. Process Type of Sleeve Diameter of the sleeve Length of the sleeve No in mm in mm D-sub 20- Kynar 1.6 mm 8 mm 1. contact 26 2 20 Kynar 1.6 mm 8 mm HDD 22D Kynar 1.2 mm 8 mm 3 Contact Butt in splice Polyolef Inner 1.6 mm 30 mm 4 in outer 2.4 mm 25 mm Ground Lug Polyolef Inner 1.6 mm 10mm 5 M3(Ring in outer 2.4 mm 12 mm termial) Spiral Splice Polyolefin Depend on the No.of 30 to 40 mm 6 wires/Gauge Lap joint Polyolef Inner 1.2 mm and 1.6 mm 8 mm 7 in outer 2.4 mm 35 to 45 mm  Soldering Process in harness 100 Shield soldering U loop multi strand wire shield termination Hook joint Spiral splice solder joint  Soldering process in harness 101 Hook solder Lap joint Lash joint joint  Solder joint defects which are cause for rejection 102 Damage to insulation (charring or burning) - Solder or flux splashes on adjacent areas - Solder icicles - Voids, pin holes, blow holes or pits - Excess solder - Insufficient solder - Cold, rosin, disturbed, grainy solder connection - De-wetting - Visible bare copper or base metal - Improper wrap --Any other discoluration on shield braid(green colour) ---Copper visibility  Reject Criteria 103 Sl.No Visual photographs Defect Remark 1. Insufficient sleeve length Not Acceptable 2 1.Lack of solder 2. Slant placement of the Not Acceptable wire 3. Shifted to edge 3 1. Solder covered up to the insulation of wire Not Acceptable 2. No sufficient insulation clearance.  Cleanliness – Flux Residue 104  Flux residue may be present if it is no-clean flux residue that is not intended to be cleaned. (No illustrations)  Flux residue does not inhibit visual inspection.  Flux residue does not inhibit access to test points of the assembly.  DEFECTS  Flux residue on, around, or bridging between non-common conductors.  Flux residue inhibits visual inspection.  Flux residue inhibits access to test points of the assembly.  Wet, tacky, or excessive flux residues that may spread onto other surfaces.  No-clean flux residue on any electrical mating surface that inhibits electrical connection  Dust cap 105 106 Chapter-5 Harness Lacing  What is Lacing & Harnessing 107 Wires shall be tied together in bundles ( known as harness) to prevent damage to insulation and the solder joints, due to vibration & shock , during testing and launch. Waxed impregnated nylon lacing thread or Dacron, nylon / tefzel cable ties shall be used for tying of wire harness. Conforming to MIL-S-23190, MIL-T-713 Fungicidal,wax coated available in different widths Following are some of the recommended methods of lacing.  Cable ties & Accessories 108 Conforming to MIL-S-23190 Material - NYLON OR TEFZEL: (A DuPont trade name for a fluorocarbon material) TYPES OF CABLE TIES Releasable Non releasable INSTALLING PROCEDURE - Select proper size of cable tie - Wrap it around the harness with ribbed side down - Pass the strap end through the boss - Pull the strap to clinch the harness - Use tie gun for tightening  Ideal for applications requiring resistance to environmental stresses such as chemical attack, gamma radiation, ultraviolet radiation and extreme temperatures.Tefzel cable ties offer high-radiation resistance and temperature stability to 302ºF. Tefzel also provides excellent resistance to ultraviolet light and meets UL flammability rating 94V-0  Harness tying and spacing 109  Equi-distance  Criss cross of wires in a bundle  Harness branches 110  Neat formation  Improper tying at splice edge  Sharp bend at crossing  Accept/Reject 111 Equidistance Crisscross lacing  Accept/Reject 112  Accept/Reject 113  Accept/Reject 114  General guidelines for harness preparation 115  Lacing shall be firmly applied yet not with excessive pressure.  Harness diameter shall not exceed 25 mm.  Wires in the bundle shall run parallel to each other.  The harness shall have minimum no of bends.  Avoid sharp bends in the harness. Radius of bend of the harness shall be minimum 6 times the diameter of the harness.  Vibration bends shall be gradual 90° bends  Lacing knot shall not be tied over vibration bend, maintain a gap of 5 mm to 10 mm between vibration bend and lacing knot  Spacing between knots shall be equal to harness diameter or 1d to 2d of the harness diameter.  Use grommet for harness passing through the metallic structure or wrap teflon / polyolefin tape and tie with lacing thread.  General guidelines for harness preparation 116  Handle the harness with utmost care.  Harness shall be clean without inclusion of foreign materials like dirt, chips, loose hardware, lacing tape scrap, etc.  Measure and record harness diameter, radius of bend for each branch in the respective connector work sheet  Avoid tying of thermal wires to the plumb lines.  Avoid sharp edges of structure  Do not use harness for hanging tools  Avoid twisting or pulling of wire bundles  Avoid stretching of wire bundles to mate connectors  Secure wire bundles to structural members by proper supports.  Prevent mechanical strain on wires / harness.  Prevent interference between wires and other equipment.  General guidelines for harness preparation 117  All semi-rigid cable, aluminium spline cable, RF flexible cables to be properly supported to the panel structure by betas and cable ties.  To avoid handling and vibration failures connectors are to be potted using RTV3145 potting compound.  Shield solder joints shall be wrapped with polyolefin tape.  QC requirements for lacing inspection 118  Check for harness diameter & radius of bend  Check the neatness & cleanliness of the harness  Check the type of knots used  Check the spacing between the knots and between knots & bend  Check the tightness of lacing  Check the support for the harness.  Check the gap between harness and package wall & frictional contact  Check for sharp bends  Check for provision of grommets  Check for the vibration bends.  Marking/Labeling 119 Markings include the content specified by the controlling document  Marking/Labeling 120  Markings include the content specified by the controlling document  Markings legible when viewed without magnification. Markings are distinct, of uniform height, and of a color that contrasts with the background  Markings remain legible after exposure to handling, assembly and required environmental testing.  Marking present in location(s) designated by controlling document  Guidelines documents 121  Check list for harness fabrication and inspection  Worksheet for harness fabrication  Guidelines for crimping and sleeve shrinking  Tool validation plan  Inspection 122 125 THANK YOU……