1、 WORLDWIDE ENGINEERING STANDARDS Test Procedure GMW8287 Highly Accelerated Life Testing (HALT) Highly Accelerated Stress Screening and Auditing Copyright 2011 General Motors Company All Rights Reserved November 2011 Originating Department: North American Engineering Standards Page 1 of 22 1 Scope .
2、3 1.1 Purpose. 3 1.2 Foreword 3 1.3 Applicability. . 3 2 References . 3 2.1 External Standards/Specifications. 3 2.2 GM Standards/Specifications. . 3 2.3 Additional References. 3 3 Resources 4 3.1 Facilities. Not applicable. . 4 3.2 Equipment. 4 3.2.1 Staffing Requirements. . 4 3.2.2 Equipment Requi
3、rements. 4 3.3 Test Vehicle/Test Piece. 5 3.4 Test Time. 5 3.5 Test Required Information. 5 3.6 Personnel/Skills. 5 4 Procedure . 5 4.1 Preparation. . 5 4.1.1 Test Equipment Setup Requirements. 5 4.1.2 Test Samples. . 5 4.1.3 Functional Testing Requirements. 6 4.2 Conditions. . 6 4.2.1 Environmental
4、 Conditions. 6 4.2.2 Test Conditions. 6 4.3 Test Reporting and Documentation. 6 4.3.1 Data Collection and Storage Requirements. 6 4.4 Instructions. . 7 4.5 HALT Test Procedure. . 7 4.5.1 Thermal Step Stress Test. 7 Figure 1: Thermal Stress Step - Temperature Profile . 7 4.5.2 Rapid Thermal Transitio
5、ns Stress Test. . 8 Figure 2: Rapid Thermal Transition Testing Temperature Profile 8 Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW8287
6、 Copyright 2011 General Motors Company All Rights Reserved November 2011 Page 2 of 22 4.5.3 Vibration Step Stress Test. . 8 Figure 3: Recommended Profile for Vibration Stress Test . 9 4.5.4 Combined Environment Stress Test. 9 Figure 4: Combined Environmental Stress Test Profile - Temperature (red) a
7、nd Vibration in Grms (blue) . 10 4.6 Reaction to the HALT Results. 10 4.6.1 Root Cause Analysis. 10 4.6.2 Corrective Action. 10 4.6.3 Verification HALT. . 11 4.6.4 Product Engineering Changes. . 11 4.7 Graphic of the Total HALT Process. 11 Figure 5: Graphic of the Total HALT Process . 12 4.7.1 Gener
8、al HALT Test Flow Example. 12 4.8 HALT in Preparation for HASS/HASA (Only if HASS/HASA is to follow). . 12 4.8.1 Lower 70% Confidence Bound Calculations. . 13 4.8.2 Safety Margin Calculations - 80% and 50%. 14 4.9 HASS/HASA. . 14 4.9.1 HASS Explained. 15 4.9.2 HASA Explained. 15 4.9.3 HASS/HASA Prep
9、aration for Production. . 15 Figure 6: Depiction of HASS Cycle Precipitating and Detecting Anomalies . 16 4.9.4 HASS in Operation 17 4.9.5 HASA in Operation 17 Figure 7: Example - Using Pareto Chart to Prioritize Issues 18 4.9.6 Interaction Between Customer and Contract Manufacturer Relative to HASS
10、/HASA. 18 4.10 Periodic Re-HALT. . 19 4.10.1 Re-HALT Assessment Method. 19 4.10.2 Degraded Design Margin. . 19 4.10.3 How Often Should Re-HALT be Conducted. 19 4.11 Summary. 19 5 Data 20 5.1 Calculations. 20 5.2 Interpretation of Results. . 20 5.3 Test Documentation. . 20 5.3.1 Records. 20 6 Safety
11、. 20 7 Notes 20 7.1 Glossary. 20 7.2 Acronyms, Abbreviations, and Symbols. . 22 8 Coding System . 22 9 Release and Revisions 22 Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,
12、-GM WORLDWIDE ENGINEERING STANDARDS GMW8287 Copyright 2011 General Motors Company All Rights Reserved November 2011 Page 3 of 22 1 Scope Note: Nothing in this standard supercedes applicable laws and regulations. Note: In the event of conflict between the English and domestic language, the English la
13、nguage shall take precedence. 1.1 Purpose. This standard is intended for use as a guideline in performing the HALT and Highly Accelerated Stress Screening/Highly Accelerated Stress Auditing (HASS/HASA) process and using the resulting data in a valid statistical control process to stabilize and impro
14、ve the product. This standard presents an acceptable and certifiable process for implementing a “common process” across diverse organizations. The goal of defining the requirements of the HALT and HASS/HASA process provides the framework for qualification of a companys HALT and HASS/HASA process thr
15、ough means of an audit. Adherence to this standard will provide the potential for companies to achieve optimal HALT and HASS/HASA effectiveness. The first step, HALT, typically results in more robust and quicker to market products. HALT is considered to be the physical test, the root cause analysis,
16、 and the corrective action. All three are critical, as the test alone will make no difference in the robustness of the product. The increased level of robustness achieved during development with HALT will be maintained during production during steps two and three using the HASS/HASA process. The dat
17、a and information obtained during HASS/HASA is most useful when good statistical process control methods are applied. These methods include control charts to view and react to the data from a “signal to noise” point of view. The other quality control method that should be used is the use of Pareto c
18、harts to assist in identification of the root cause of problems and maintain focus on the vital few causes that dominate the source of problems. 1.2 Foreword. The process elements to successfully implement and perform Highly Accelerated Life Testing (HALT) and Highly Accelerated Stress Screening/Hig
19、hly Accelerated Stress Auditing (HASS/HASA) are defined in this standard. This standard identifies technical responsibilities, equipment requirements, testing practice competencies, and statistical quality control methods that will optimize the total process. Adherence to this document will provide
20、management and test personnel with a common process that represents a collection of “best practices”. Procedures are explained in detail; however, the basic nature of the HALT process is one of discovery that requires flexibility of process as it progresses. Consider the HALT related numerical value
21、s and procedures as a general guideline. Each product that is destined for the HALT process will dictate its own unique set of test values and stress steps. Accept the ambiguity that is intrinsic to an explorative development test. This standard applies to a diversified mix of product segments, incl
22、uding electronic assemblies and electro-mechanical assemblies, and may be applicable to certain mechanical assemblies as well. Note: The use of the acronym HALT has become universally used and accepted by a wide range of industries as a generic reference to a specific type of accelerated testing whi
23、ch uses a combination of very rapid temperature change and all axis broadband vibration. Several manufacturers now produce HALT like test chambers, and General Motors does not endorse any one brand over any other brand, even though the most commonly used acronym of HALT is used exclusively in this d
24、ocument. 1.3 Applicability. HALT applies to new technology/designs and can also be used to evaluate product improvements. HASS and HASA are used to detect unexpected and random quality issues during production. 2 References Note: Only the latest approved standards are applicable unless otherwise spe
25、cified. 2.1 External Standards/Specifications. None 2.2 GM Standards/Specifications. None 2.3 Additional References. Accelerated Reliability Engineering, Gregg K. Hobbs, John Wiley however it must, at a minimum, be performed at the conclusion of the ten-minute dwell. 4.5.3.3 A return to a “tickle vi
26、bration level” (5 3) Grms) is recommended at the end of each vibration step to detect possible failures that are masked by the extreme forces occurring at the higher vibration levels. Detection of cracked solder joints is noticeably improved by this technique. 4.5.3.4 The vibration step stress is co
27、ntinued until the operational limit of the sample is determined or the chamber maximum is achieved. 4.5.3.5 Once the operating limit is determined, the process of incrementing the vibration stress in the previously defined increments continues beyond the operational limit to the destruct limit or th
28、e chamber maximum. However, because the sample may not be fully operational, it is especially important to return to the “tickle level vibration” between each dwell to determine whether the sample is still functional. Figure 3: Recommended Profile for Vibration Stress Test 4.5.4 Combined Environment
29、 Stress Test. See Figure 4. 4.5.4.1 A minimum of five (5) Combined Environment cycles is required unless a destructive failure is encountered prior to completion of all five cycles. 4.5.4.2 The thermal profile for the Combined Environment Test is performed by cycling between the thermal operational
30、limits (or modified operational limits, when special circumstances like softening plastic exist). The modified operational limits have a reduced range to ensure that chamber overshoot does not cause destructive failure. The minimum dwell period at each thermal extreme is ten (10) minutes. 4.5.4.3 Th
31、e starting vibration level for the five (5) required cycles is determined by dividing the maximum vibration level applied during Vibration Step Stress by five. The vibration level is increased by the same amount during each subsequent thermal cycle (i.e., if the sample experienced a destruct failure
32、 at 35 Grms during the Vibration Step Stress, the initial test cycle would be conducted at a vibration level of 7 Grms. The vibration level would be increased by 7 Grms after each complete thermal cycle - Cycle 1: 7 Grms, Cycle 2: 14 Grms, Cycle 3: 21 Grms, Cycle 4: 28 Grms, Cycle 5: 35 Grms). If a
33、destruct limit was not determined during Vibration Step Stress, then the maximum vibration level attained is divided by five. Note that smaller starting vibration levels and increment levels may be used. 4.5.4.4 A return to a “tickle vibration level” (5 3) Grms) is recommended at the end of each vib
34、ration step to detect possible failures that are masked by the extreme forces occurring at the higher vibration levels. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORL
35、DWIDE ENGINEERING STANDARDS GMW8287 Copyright 2011 General Motors Company All Rights Reserved November 2011 Page 10 of 22 Figure 4: Combined Environmental Stress Test Profile - Temperature (red) and Vibration in Grms (blue) 4.6.4.5 Functional testing of the sample is required following all dwell per
36、iods of the test cycle. The dwell period is extended accordingly to accommodate the length of the functional test. Note that the functional test should be performed throughout the step; however it must be performed, at a minimum, at the conclusion of the ten-minute dwell. 4.6 Reaction to the HALT Re
37、sults. The process continues after discovering the failure modes in the HALT. The next step is to determine why the failure(s) occurred, performing a true root cause analysis on each failure, and deciding what corrective action may be appropriate. Engineering decisions need to be made, and justified
38、, regarding the action that will be taken from the HALT results. The entire process from identification of weaknesses to corrective action should be clearly tied into the problem reporting and tracking process. This could take the form of response to action items identified during a design failure m
39、ode and effects analysis (DFMEA), or an incident tracking process for development and validation. 4.6.1 Root Cause Analysis. An integral part of the HALT process is the determination of the root cause of the failures identified from the test. This process may involve the need for a failure analysis
40、lab, whether in-house or external. Attributing a root cause to a specific failure requires a full understanding of the problem. When the cause is understood, the appropriate corrective action should be pursued. Engineering judgment to balance total life cycle costs must be made to assess what correc
41、tive action will be performed to eliminate, minimize, or live with this failure. The root cause analysis process must be fully documented relative to: the failure mode, the exact cause of the failure, or the suspected cause of the failure. This should include the results of a failure analysis lab, i
42、f used, with pictures of damage at the flawed site. Tracking of the process - documentation/reporting process. The process is defined and followed for all root cause analysis investigations. This should include a procedure and a reporting structure for review and decision making authority to assess
43、completeness and accuracy of the analysis. The facility shall have failure analysis capability, or may utilize an external or independent facility to perform this responsibility. The RCA process begins during the HALT test. As functional limitations or failures are encountered, efforts are made to u
44、nderstand the failure mode. This can be accomplished by some limited sample ruggedization implemented during the HALT service. This is beneficial to allow the sample to be stressed at higher levels of stress in order to find additional failure modes. Another method in which further stress levels can
45、 be investigated is through component isolation (i.e., placing a weaker component external to the HALT chamber and wiring it to the sample within the chamber to maintain system functionality). 4.6.2 Corrective Action. A corrective action plan is incorporated following adequate understanding of the f
46、ailure mode. The manufacturer is responsible for documenting, reporting, and implementing all reasonable corrective action for design and process defects identified during the HALT. 4.6.2.1 The corrective actions “fixes“ are summarized with a cause and effect report for review by the appropriate dec
47、ision-makers within the company. This shall include a cost estimate and/or justification of the Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDA
48、RDS GMW8287 Copyright 2011 General Motors Company All Rights Reserved November 2011 Page 11 of 22 redesign and estimated product design margin improvement. Based on this assessment, a decision is made either to implement the redesign changes or to leave the product unmodified. 4.6.2.2 The engineerin
49、g redesign decision process is defined and followed for all corrective actions. This should include a procedure and a reporting structure for review and decision-making authority to assess completeness and accuracy of the information reported. 4.6.3 Verification HALT. This HALT process is performed following the corrective action process when a product is redesigned. The design or process changes to the product must be incorporated in the product
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