1、 Institute of Environmental Sciences and Technology IEST-RP-PR001.2 Product Reliability Division Recommended Practice 001.2 Management and Technical Guidelines for the Environmental Stress Screening (ESS) Process Arlington Place One 2340 S. Arlington Heights Road, Suite 620 Arlington Heights, IL 600
2、05-4510 Phone: (847) 981-0100 Fax: (847) 981-4130 E-mail: informationiest.org Web: www.iest.org 2 Copyrighted material Institute of Environmental Sciences and Technology IEST-RP-PR001.2 This Recommended Practice was prepared by and is under the jurisdiction of Working Group 001 of the IEST Product R
3、eliability Division (WG-PR001). The following WG voting members contributed to the development of this edition of this Recommended Practice. William T. Boswell, WG-PR001 Chair, Consultant Dustin S. Aldridge, Raytheon Missile Systems Christine L. Peterson, C. Hanse Industries Michael A. Roy, Consulta
4、nt David M. Sgro, FLIR The Working Group also wishes to acknowledge the contributions of members who prefer to remain anonymous. Copyright 2016 by the Institute of Environmental Sciences and Technology First printing, July 2016 ISBN: 978-1-937280-29-1 (Electronic format) ISBN: 978-1-937280-28-4 (Pri
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6、this document, please use the online Proposal for Improvement form found on the IEST website at www.iest.org. Institute of Environmental Sciences and Technology Arlington Place One 2340 S. Arlington Heights Road, Suite 620 Arlington Heights, IL 60005-4510 Phone: (847) 981-0100 Fax: (847) 981-4130 E-
7、mail: informationiest.org Web: www.iest.org IEST-RP-PR001.2 Institute of Environmental Sciences and Technology Copyrighted material 3 NOTICE AND DISCLAIMER: This Recommended Practice is published by the Institute of Environmental Sciences and Technology (IEST) to advance the technical and engineerin
8、g sciences. Use of this document is entirely voluntary, and determination of its applicability and suitability for any particular use is solely the responsibility of the user. Use of this Recommended Practice does not imply any warranty or endorsement by IEST. The information in this publication was
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10、ecommended practices, and guideline publications, of which the document contained herein is one, are developed through a voluntary consensus standards development process. This process brings together volunteers and seeks out the views of persons who have an interest in the topic covered by this pub
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18、ST and is solely the responsibility of the certifier or maker of the statement. 4 Copyrighted material Institute of Environmental Sciences and Technology IEST-RP-PR001.2 Management and Technical Guidelines for the Environmental Stress Screening (ESS) Process IEST-RP-PR001.2 CONTENTS SECTION 1 SCOPE
19、AND LIMITATIONS . 6 2 REFERENCES AND APPLICABLE DOCUMENTS . 7 3 TERMS AND DEFINITIONS . 8 4 BACKGROUND AND PURPOSE . 13 5 ESS FUNDAMENTALS . 13 6 EQUIPMENT AND SETUP 29 7 PROCEDURES 36 FIGURES 1 DYNAMICS OF THE SCREENING PROCESS . 21 2 DELIVERABLE PRODUCT FAILURE-FREE OPERATION 25 3 SCREENING CONFIG
20、URATION EXAMPLE . 32 4 RESPONSE OF CCA “A” TO FIXED RS INPUT 32 5 RESPONSE OF CAA “A” TO ED SYSTEM INPUT 34 6 ENVIRONMENTAL SEVERITY RELATIONSHIPS 37 7 SCREEN DEVELOPMENT AND VALIDATION PROCESS 40 8 PRODUCT THERMAL RESPONSE DURING THERMAL CYCLING SCREENING 45 A1 STRESS RELATIONSHIP OF ENVIRONMENTAL
21、LEVELS . 49 A2 FIRST-ORDER LIFE ASSESSMENT METHODOLOGY 52 A3 PHYSICS OF FAILURE VIBRATION APPROACH . 53 B1 TYPICAL BOX LEVEL ASSEMBLY PLAN VIEW . 57 B2 RESPONSE MEASUREMENT LOCATIONS ON RECTANGULAR CCA WITH BASE CONNECTOR 57 C1 PREDICTION OF THERMAL CYCLE FATIGUE LIFE REDUCTION DUE TO CONTAMINATED S
22、OLDER JOINTS . 63 C2 PHYSICS OF FAILURE THERMAL APPROACH 68 C3 TYPICAL TEMPERATURE CYCLING PROFILE AND PRODUCT THERMAL RESPONSE69 C4 CHAMBER AIR AND PRODUCT TEMPERATURES WITH HIGH CHAMBER AIR SPEED AND LONG DWELL TIMES . 70 C5 CHAMBER AIR AND PRODUCT TEMPERATURES WITH LOW CHAMBER AIR SPEED AND SHORT
23、 DWELL TIMES . 70 IEST-RP-PR001.2 Institute of Environmental Sciences and Technology Copyrighted material 5 TABLES 1 CHARACTERISTICS OF A WELL-DESIGNED SCREEN. . 14 2 EFFECT OF DEFECTIVE PIECE PARTS ON PRINTED WIRING ASSEMBLY YIELD. . 20 3 ESS PLAN CHECKLIST. 22 4 SCREENING ENVIRONMENTS VERSUS TYPIC
24、AL FAILURE MECHANISMS. . 23 5 VIBRATION SCREEN CHECKLIST. . 42 6 THERMAL CYCLING SCREEN CHECKLIST. 44 A1 CONSIDERATIONS IN SELECTION OF SCREENING DEVELOPMENT METHOD. . 48 B1 VIBRATION SURVEY CHECKLIST. 60 D1 THERMAL SURVEY CHECKLIST. . 77 APPENDIXES A VIBRATION STRESS SCREENING CHARACTERISTICS DEVEL
25、OPMENT . 47 B VIBRATION SURVEY GUIDELINES 56 C THERMAL CYCLING STRESS SCREENING CHARACTERISTICS DEVELOPMENT 61 D THERMAL SURVEY GUIDELINES 75 E SUPPLIER ESS PROCESS REQUIREMENTS 79 F FIXTURES FOR ESS. 81 G BIBLIOGRAPHY . 83 6 Copyrighted material Institute of Environmental Sciences and Technology IE
26、ST-RP-PR001.2 Institute of Environmental Sciences and Technology Product Reliability Division Recommended Practice 001.2 Management and Technical Guidelines for the Environmental Stress Screening (ESS) Process IEST-RP-PR001.2 1 SCOPE AND LIMITATIONS 1.1 Scope This Recommended Practice (RP) supersede
27、s IEST-RP-PR001.1, Management and Technical Guidelines for the ESS Process (1999). This RP provides an overview of the techniques and considerations needed to define a viable Environmental Stress Screening (ESS) program. This RP uses language that can be used by the military, government, and commerc
28、ial communities. This RP is intended to be an important tool that can be used by the electronics industry for conducting ESS. This document applies to a knowledgeable ESS practitioner as well as to those individuals who are new to ESS. Additionally, it provides the practitioner all of the tools requ
29、ired to successfully plan, develop, and implement a viable ESS program. The process elements required to successfully implement ESS are discussed in this document, as well as those process steps necessary to keep the ESS process dynamic; i.e., successful planning, implementation of ESS, the collecti
30、on of failure data, the analysis of failures, and implementation of corrective action. It is not the intent of this document to describe engineering development or formal verification environmental tests. These subjects are valuable parts of the product development process, but because of their dept
31、h and complexity are beyond the scope of this document. Rather, this document describes the application of thermal, vibration, and electrical performance as forcing functions during the ESS process because of their nearly universal utility. However, other types of forcing functions (such as pressure
32、 cycling) or performance evaluation (X-ray and infrared scanning, for example) may be appropriate in special circumstances for particular products. This document should not be construed as discouraging the application of other relevant forcing functions when appropriate. This document stresses the n
33、eed to expose product to forcing functions as early in the life of the product as possible. This will assist in producing the best product possible given requisite economic considerations. It is recognized that a product will likely be composed of several different assemblies. As these assemblies ar
34、e integrated and the product becomes more and more complex, the level of environmental loading that the lower level assemblies may experience can be greatly attenuated (i.e., thermal path restrictions and vibration dampening). With this in mind, and realizing that all assemblies are prone to process
35、 anomalies, this document emphasizes the need to perform ESS at the lowest practical assembly level. This RP discusses the screening environments of temperature cycling, random vibration, and power cycling. For each of these environments, a discussion of the steps required to successfully incorporat
36、e them into the ESS program IEST-RP-PR001.2 Institute of Environmental Sciences and Technology Copyrighted material 7 is provided. This discussion includes facility requirements, establishing screening parameters based on product response to a forcing function, and how to keep the ESS process dynami
37、c. Furthermore, every opportunity is given to tailor ESS parameters to account for both the inherent design capability and the customer working environment as it pertains to production of the product. This document was prepared and updated by the IEST ESS Technical Committee Working Group to provide
38、 industry and government agencies with the latest thinking and experience to assist in the development and implementation of technically sound, cost-effective stress screening programs. 1.2 Limitations This document is published by IEST to advance the state of technical and engineering sciences and
39、is intended for guidance only. This RP does not recommend a specific screening implementation, screening environment, or screening parameter(s). Sound engineering judgment, as well as product and process knowledge, should be employed so that the specific application of these process steps considers
40、the specific product characteristics, product phase, and the prevailing business strategy. The use of this document is entirely voluntary, and its application and suitability for any particular use is the sole responsibility of the user. 2 REFERENCES AND APPLICABLE DOCUMENTS The editions of the foll
41、owing documents that are in effect on the date of invitation for bids or solicitation for offers are incorporated into this RP to the extent specified herein. 2.1 Institute of Environmental Sciences and Technology (IEST) IEST-RD-DTE012.2: Handbook for Dynamic Data Acquisition and Analysis IEST-RP-PR
42、003: HALT and HASS 2.2 Other references Harris, C. M. 2010. Shock and Vibration Handbook. 6th Edition. New York: McGraw Hill. Steinberg, D. S. 2000. Vibration Analysis for Electronic Equipment. 3rd edition. Hoboken, NJ: John Wiley the ability of a product to withstand environmental conditions based
43、on results found during analysis, test, or both. Q (sharpness of resonance) A dimensionless value calculated by dividing the natural frequency by the bandwidth of the half power points associated with that natural frequency. The Q at any mode can be calculated for a PSD response value in g2/Hz or a
44、peak response value in g. For PSD data, the bandwidth is determined by measuring the frequency at each half power point (0.5 of the peak g2/Hz value); for sine data, the bandwidth is determined by measuring the frequency at each IEST-RP-PR001.2 Institute of Environmental Sciences and Technology Copy
45、righted material 11 half power point (0.707 of the peak g value). Q can be calculated at any natural frequency, but is best calculated from transfer function data to avoid peaks that are misshapen due to abrupt changes in the input spectrum. random vibration (see vibration, random) repetitive shock
46、(RS) system A system in which the vibration table is excited with repeated shock pulses. This is typically accomplished with a number of pneumatic hammers attached to the vibration table. resonance A frequency at which a structure amplifies vibration input. resonance search Exposing a product to vib
47、ration over a range of frequencies while monitoring the product response with the purpose of identifying resonances. resonant frequency Frequency or narrow frequency band in a product that, when excited by vibration, can result in damage to good product, or consume a significant amount of useful lif
48、e, or both. sample test (see test, sample) screen The process of forcing defects to identifiable levels. A successful screen will uncover defects leading to actions that prevent marginal hardware from being delivered to the customer. screen validation A test performed to verify that a significant po
49、rtion of the useful life of the product has not been consumed by the forcing function. screening A process or combination of processes applied to 100% of a lot or to an entire group of like products, this is an audit to identify and eliminate defects. seeded sample A test sample that is known to have a defect and is used to verify the effectiveness of a test. The sample may be a field return or a piece that is purposely weakened by the tester. sinusoidal vibration (see vibration, sinusoidal) soft failure (see failure, soft) step stress testing An experimental process
