REG NASA-STD-8739 1 REV A W CHG 2-2011 WORKMANSHIP STANDARD FOR POLYMERIC APPLICATION ON ELECTRONIC ASSEMBLIES.pdf

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1、 NASA TECHNICAL STANDARD NASA-STD-8739.1A With Change 2 National Aeronautics and Space Administration Washington, DC 20546 Approved: 2008-03-04 Change 2 Approved: 2011-03-29 WORKMANSHIP STANDARD FOR POLYMERIC APPLICATION ON ELECTRONIC ASSEMBLIES Measurement System Identification: Metric (English) Re

2、quests for Relief from the requirements in this document are processed through the NASA Safety and Mission Assurance Technical Authority per NPR 8715.3 paragraph 1.13 APPROVED FOR PUBLIC RELEASE DISTRIBUTION IS UNLIMITED Provided by IHSNot for ResaleNo reproduction or networking permitted without li

3、cense from IHS-,-,-NASA-STD 8739.1A with Change 2 Page 2 of 73 This page intentionally left blank. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA-STD 8739.1A with Change 2 Page 3 of 73 DOCUMENT HISTORY LOG Status Document Revision Approval Date

4、 Description Baseline 1999-08-06 Initial Release Revision A Update/ Revise 2008-03-04 Technical corrections and addition of sections covering bonding and encapsulation. Change 1 2009-07-23 Editorial errata to paragraphs 2.1.2, 2.1.3, 4.1.4, 4.5.2.a, 5.1.3, 5.2.1, 5.5.1, 6.2.2, 6.3.1.1, 6.5.1.a, 6.6.

5、1.b, 6.6.2.b, 6.8.1.2, Table 6-1, 8.1.3, 8.4.4, Table 8-1 Notes 2/4, 9.1.2.3, 9.1.2.4, 9.1.3.f, 9.1.4.3.c/d/e/f/g, 9.2.1.2, Figures 9-1/2/3/4/5/6/7/10, 10.2.5, 10.2.7.f, Figure 10-3, Table 10-1, 12.3, 12.3.2/3/6/8, Figures 12-1/2, 13.2.2.a, 13.3.g, 13.6.2.d/i thru p, 13.6.3.b/g, 13.7.2.a. 13.7.3.d/e

6、, 13.8.1, 13.9.2.j, 13.10.3, 13.11.3.c/d (JWL4)Change 2 2011-03-29 Editorial errata to Foreword paragraph 2, and paragraphs 1.0, 1.3, 1.4.1, 1.4.2, 4.2.2, and 12.1. Format Page numbers. Add reference to NASA-STD 8709.22 in paragraphs 2.1.2 and 3.2. (JWL4)This document is subject to reviews per Offic

7、e of Management and Budget Circular A-119, Federal Participation in the Development and Use of Voluntary Standards (02/10/1998) and NPD 7120.4, NASA Engineering and Program/Project Management Policy. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NA

8、SA-STD 8739.1A with Change 2 Page 4 of 73 This page intentionally left blank. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA-STD 8739.1A with Change 2 Page 5 of 73 FOREWORD This NASA Standard (NASA-STD) is published by the National Aeronautics

9、and Space Administration (NASA) to provide uniform engineering and technical requirements for processes, procedures, practices, and methods that have been endorsed as standard for NASA programs and projects, including requirements for selection, application, and design criteria of an item. Use of th

10、is NASA-STD is the responsibility of the user as required by NASA Policy Directive (NPD) 8730.5, NASA Quality Assurance Program Policy. This NASA-STD is approved for use by NASA Headquarters and NASA Centers, including Component Facilities. This NASA-STD may be applied on contracts for spacecraft, a

11、ircraft, balloon payloads, instruments, or launch vehicles. The requirements herein prescribe NASAs technical requirements, procedures, and documenting requirements for staking, conformal coating, bonding, and encapsulation of printed wiring boards and electronic assemblies. These may be tailored to

12、 the program applications to obtain the most cost effective, best quality product. These requirements describe basic considerations necessary to ensure reliable staking, conformal coating, bonding, and encapsulation of printed circuit boards and electronic assemblies. Included are requirements which

13、 establish the responsibility for documenting fabrication and inspection procedures to be used for NASA work including supplier innovations, special processes, and changes in technology. For the purpose of this document, the term “supplier” is defined as in-house NASA, NASA contractors, and subtier

14、contractors. Requests for information, corrections, or additions to this NASA-STD can be submitted via “Feedback” in the NASA Technical Standards System at http:/standards.nasa.gov. This NASA-STD was developed by the NASA Headquarters Office of Safety and Mission Assurance, Safety and Assurance Requ

15、irements Division and the NASA Workmanship Technical Committee which is managed by NASA Goddard Space Flight Center. s/ Bryan OConnor March 4, 2008 Bryan OConnor Approval Date Chief, Safety and Mission Assurance NASA-STD 8739.1 Change 2 approved by: Michael G. Stamatelatos, Ph.D. on 29 March 2011 Th

16、is version supersedes: NASA-STD 8739.1A with Change 1 dated July 23, 2009 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA-STD 8739.1A with Change 2 Page 6 of 73 NASA Technical Standards for Mission Hardware and Mission-Critical Ground Support Eq

17、uipment NASA Technical Standards can be found on the World Wide Web at URL address http:/standards.nasa.gov/public/public_query_NASA_stds.taf. Title Number Workmanship Standard for Staking and Conformal Coating of Printed Wiring Boards and Electronic Assemblies NASA-STD 8739.1A with Change 2 Workman

18、ship Standard for Surface Mount Technology NASA-STD 8739.2 with Change 2 Soldered Electrical Connections NASA-STD-8739.3 with Change 4 Crimping, Interconnecting Cables, Harnesses, and Wiring NASA-STD-8739.4 with Change 6 Fiber Optic Terminations, Cable Assemblies, and Installation NASA-STD-8739.5 wi

19、th Change 2 NOTE: NASA-STD-8739.7, Standard for Electrostatic Discharge Control (Excluding Electrically Initiated Explosive Devices), was referenced in earlier versions of this document as a NASA Technical Standard for Flight Hardware Workmanship. It has been replaced with ANSI/ESD S20.20, Protectio

20、n of Electrical and Electronic Parts, Assemblies and Equipment (Excluding Electrically Initiated Explosive Devices) Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA-STD 8739.1A with Change 2 Page 7 of 73 TABLE OF CONTENTS 1. SCOPE. 11 1.1 Purpose

21、 11 1.2 Applicability . 11 1.3 Special Requirements 11 1.4 Approval of Departures from this Standard 11 2. APPLICABLE DOCUMENTS . 12 2.1 Applicable Documents 12 2.1.1 General 12 2.1.2 Government Documents . 12 2.1.3 Non-Government Documents . 12 3. ACRONYMS AND DEFINITIONS . 13 3.1 Acronyms 13 3.2 D

22、efinitions. 14 4. GENERAL REQUIREMENTS 18 4.1 General 18 4.2 Documentation 18 4.3 Rework and Repair . 18 4.4 Electrostatic Discharge Requirements 19 4.5 Selection and Approval Requirements for Polymeric Materials 19 5. TRAINING AND CERTIFICATION PROGRAM 22 5.1 General 22 5.2 Vision Requirements . 22

23、 5.3 Personnel Certification Levels 23 5.4 Training Program Requirements . 23 5.5 Documentation 24 5.6 Maintenance of Certification Status 24 5.7 Training Resources . 25 6. FACILITIES, TOOLS, AND MATERIALS . 26 6.1 Safety 26 6.2 Facility Cleanliness . 26 6.3 Environmental Conditions 26 6.4 Silicone

24、Operations . 27 6.5 Tool and Equipment Control 27 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA-STD 8739.1A with Change 2 Page 8 of 73 6.6 Material Storage and Records Retention 28 6.7 Inspection Optics 29 6.8 In-Process Storage and Handling 2

25、9 6.9 Solvents . 29 7. CLEANLINESS REQUIREMENTS 31 7.1 General 31 7.2 Cleanliness Testing . 31 7.3 Test Limits 32 7.4 Resistivity of Solvent Extract . 32 7.5 Sodium Chloride Salt Equivalent Ionic Contamination Test 32 8. PREPARATION FOR POLYMERIC APPLICATIONS 34 8.1 Surface Preparation . 34 8.2 Mask

26、ing. 34 8.3 Priming 34 8.4 Material Preparation 36 8.5 Test Specimen . 38 8.6 Conformal Coating Specimens . 38 9. STAKING . 39 9.1 Requirements 39 9.2 Fastener Staking 47 9.3 Torque Striping . 49 10. CONFORMAL COATING . 50 10.1 Purpose 50 10.2 Conformal Coating Application 50 10.3 Curing . 53 10.4 C

27、leanup . 53 10.5 Touchup/Rework. 53 11. BONDING . 58 11.1 General 58 11.2 Bonding . 58 12. ENCAPSULATION . 60 12.1 General 60 12.2 Pre-cure Examination 60 12.3 Post-cure Inspection 60 12.4 Potting Connectors used with Shielded Cable 62 Provided by IHSNot for ResaleNo reproduction or networking permi

28、tted without license from IHS-,-,-NASA-STD 8739.1A with Change 2 Page 9 of 73 12.5 Cleanup . 62 13. QUALITY ASSURANCE 63 13.1 General 63 13.2 Documentation Verification 63 13.3 Documentation Authorization . 64 13.4 Verification of Tools, Equipment, and Materials . 64 13.5 General Inspection Methods

29、for Polymeric Applications . 64 13.6 Acceptance/Rejection Criteria for Staking . 65 13.7 Acceptance/Rejection Criteria for Fastener Staking and Torque Striping 67 13.8 Inspection Methods for Conformal Coating . 68 13.9 Acceptance/Rejection Criteria for Conformal Coating . 68 13.10 Acceptance/Rejecti

30、on Criteria for Bonding 69 13.11 Acceptance/Rejection Criteria for Encapsulation . 70 APPENDIX A. CONFORMAL COATING PROBLEMS . 72 A.1 Conformal Coating Thickness 72 A.2 Coverage Points and Edges 72 A.3 Bubbles . 72 LIST OF FIGURES Figure 9-1: Default Staking for Horizontally-Mounted Sleeveless Cylin

31、drical Part . 42 Figure 9-2: Default Staking for Horizontally-Mounted Sleeved Cylindrical Parts . 42 Figure 9-3: Default Staking of a Single Vertically-Mounted Rectangular Part . 43 Figure 9-4: Default Staking for an Array of Vertically-Mounted Rectangular Parts 43 Figure 9-5: Staking for Radial Lea

32、d Components . 44 Figure 9-6: Staking for Radial Multi-lead Rectangular Components 44 Figure 9-7: Wire Bundle Staking . 45 Figure 9-8: Single Wire Staking 45 Figure 9-9: Toroid Staking . 46 Figure 9-10: Vibration Dampening Staking 47 Figure 9-11: Locking of Screws and Bolts with Nuts 48 Figure 9-12:

33、 Thread Locking of Blind Screw 49 Figure 9-13: Torque Striping Methods 49 Figure 10-1: Spray Application . 51 Figure 10-2: Conformal Coating Bubbles . 54 Figure 10-3: Conformal Coating Scratches 55 Figure 10-4: Conformal Coating - Lifting and Peeling . 56 Figure 10-5: Conformal Coating Coverage Defe

34、cts . 57 Figure 11-1: Component Bonding - Excess Bonding Material . 59 Figure 12-1: Encapsulating Wires at Connector 61 Figure 12-2: Module Encapsulation . 62 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA-STD 8739.1A with Change 2 Page 10 of 7

35、3 LIST OF TABLES Table 6-1: Solvent and Cleaners 30 Table 7-1: Cleanliness Test Values 33 Table 8-1: Demoisturizing Schedules for Polymeric Applications Surface Preparation . 35 Table 10-1: Conformal Coating Thickness 52 Provided by IHSNot for ResaleNo reproduction or networking permitted without li

36、cense from IHS-,-,-NASA-STD 8739.1A with Change 2 Page 11 of 73 1. SCOPE This standard prescribes NASAs technical requirements, procedures, and documentation requirements for polymeric applications for electrical and electronic assemblies. 1.1 Purpose This publication sets forth requirements for sta

37、king, conformal coating, bonding, and encapsulation of components used in electronic hardware. 1.2 Applicability This publication is applicable to NASA programs involving polymeric applications for flight hardware, mission critical ground support equipment, and elements thereof and wherever invoked

38、contractually. 1.3 Special Requirements Special requirements that are not in conformance with the requirements of this publication and which are documented in the engineering drawings shall be traceable to prior NASA approval (also see 1.4) (Requirement). 1.4 Approval of Departures from this Standar

39、d 1.4.1 Minor departures from this standard require prior written approval from the NASA project management. In addition, for non-NASA suppliers, written approval is required from the cognizant NASA contracting officer. The supplier is responsible for assuring that any departures from this publicati

40、on are evaluated by, coordinated with, and submitted for approval prior to use or implementation. Departures which reduce the requirements herein may warrant a request for relief per NASA-STD-8709.20, Management of Safety and Mission Assurance Technical Authority. 1.4.2 Reserved. Provided by IHSNot

41、for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA-STD 8739.1A with Change 2 Page 12 of 73 2. APPLICABLE DOCUMENTS 2.1 Applicable Documents 2.1.1 General The documents listed in this section contain provisions that constitute requirements of this NASA-STD. The latest

42、 issuance of cited documents is to be used unless otherwise approved by the assigned Technical Authority. The applicable documents are accessible via the NASA Online Directives Information System at http:/nodis3.gsfc.nasa.gov/, the NASA Technical Standards website at http:/standards.nasa.gov, or dir

43、ectly from the Standards Developing Organizations (SDOs) or other document distributors. 2.1.2 Government Documents 27 CFR 21.35 Code of Federal Regulations, Title 27, Alcohol, Tobacco and Firearms, Part 21, Formulas for Denatured Alcohol and Rum, Subpart D, Specially Denatured Spirits Formulas and

44、Authorized Uses, Formula No. 3-A O-M-232 Methanol (Methyl Alcohol) NASA-STD-6001 Flammability, Odor, Offgassing and Compatibility Requirements and Test Procedures for Materials in Environments that Support Combustion NASA-STD 8709.22 Safety and Mission Assurance Terms and Definitions NPD 8730.5 NASA

45、 Quality Assurance Program Policy OSHA Standards Occupational Safety and Health Administration (OSHA), Title 29, Code of Federal Regulations (CFR), Part 1910, Occupational Safety and Health Standards. TT-I-735A Specification for Isopropyl Alcohol 2.1.3 Non-Government Documents ANSI/NCSL Z540.1 Requi

46、rements for the Calibration of Measuring and Test Equipment ASTM-D-1007 Standard Specification for sec-Butyl Alcohol ASTM-D-2240 Standard Test Method for Rubber Property Durometer Hardness ASTM-E-595 Standard Test Method for Total Mass Loss and Collected Volatile Condensable Materials From Outgassin

47、g in a Vacuum Environment ANSI/ESD S20.20 Standard for Electrostatic Discharge Control (Excluding Electrically Initiated Explosive Devices) Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NASA-STD 8739.1A with Change 2 Page 13 of 73 3. ACRONYMS AND D

48、EFINITIONS 3.1 Acronyms The following acronyms apply to terms used in this Standard. CFR Code of Federal Regulations CTE Coefficient of Thermal Expansion CVCM Collected Volatile Condensable Material CVD Chemical Vapor Deposition DIP Dual-In-Line Package DOT Department of Transportation EEE Electrical, Electronic, and Electromechanical EPA Environmental Protection Agency ESD Electrostatic Discharge GSFC Goddard Space Flight Center JPL Jet Propulsion Laboratory MSDS Material Safety Data Sheet NASA National Aeron