1、 WORLDWIDE ENGINEERING STANDARDS Test Procedure GMW8288 General Specification for Thermal Evaluations Using Thermocouple and Infrared Imaging Methods Copyright 2012 General Motors Company All Rights Reserved July 2012 Originating Department: North American Engineering Standards Page 1 of 38 1 Scope
2、Note: Nothing in this standard supercedes applicable laws and regulations. Note: In the event of conflict between the English and domestic language, the English language shall take precedence. Note: The Component Technical Specification (CTS) and Subsystem Technical Specification (SSTS) shall take p
3、recedence over this standard. 1.1 Purpose. This standard specifies standard Thermocouple and Infrared imaging thermal measurement methods for components with electrical/electronic content that shall be used for thermal evaluations, unless otherwise specified. 1.2 Foreword. This standard defines the
4、following two temperature measurement methods for components with electrical/electronic content that are used in a vehicle environment: Thermocouple (TC) Infrared (IR) imaging 1.3 Applicability. This standard applies to components with Electrical/Electronic (E/E) content to measure thermal propertie
5、s. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ISO 9000 QS 9000 2.2 GM Standards/Specifications. GMW3172 2.3 Additional References. ASNT-TC-1A Level II Certification 3 Resources 3.1 Facilities. The test facil
6、ities shall have the equipment and personnel expertise required to execute the procedures described within this document. All facilities and test equipment shall be QS 9000 or ISO 9000 certified. 3.2 Equipment. 3.2.1 Calibration. All equipment that is used for conducting thermal measurements shall h
7、ave valid calibration labels. 3.2.2 Working Condition. All temperature measurement equipment shall demonstrate proper operation prior to the temperature measurement. 3.2.3 Parameter Definition and Tolerance. Unless stated otherwise, Table 1 shall define the test environmental parameters and toleranc
8、es to be used. 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 GMW8288 Copyright 2012 General Motors Company All Rights Reserved July 2012 P
9、age 2 of 38 Table 1: Environmental Parameters and Tolerances Parameter Tolerance Temperature As Specified, ( 3) C Test Time As Specified, ( 0.5)% Room Ambient Relative Humidity 30% to 70% Unless stated otherwise, Table 2 shall define the measurement equipment tolerances to be used. Table 2: Measure
10、Equipment Tolerances Parameter Tolerance Temperature ( 0.1) C Voltage As Specified, ( 0.1) V (as measured at the component) Current As Specified, ( 1)% 3.2.4 Thermal Test Chamber. The test chamber shall be capable of a temperature range of -40 C to +100 C minimum for evaluations of passenger compart
11、ment components. A -40 C to +160 C chamber is required for engine compartment components. The chamber shall have access ports for the interface and instrumentation wiring. 3.2.5 IR-Specific Equipment. 3.2.5.1 Calibration of IR Equipment. If absolute temperature-scale readings are required (as oppose
12、d to simple thermal pattern viewing or relative temperature readings), then the IR camera shall be calibrated to the emissivity of the materials being imaged prior to the thermal evaluation procedure. Calibration shall be performed per the recommended procedures of the camera manufacturer. Separate
13、calibration shall be performed for each combination of filters, lenses, and window materials used in the procedure. Window materials are to be calibrated for each IR camera wavelength range setting used. It is recommended that the IR camera used in electrical component or printed circuit board therm
14、al assessments be calibrated and filtered for peak performance in the 15 C to 150 C range. Better performance in this temperature range is achieved by using a camera that detects in the 8 m to 14 m spectral region instead of the 3 m to 5 m spectral region. The camera shall be mounted on a tripod or
15、an equivalent fixture to ensure image stability. 3.2.5.2 Image Display, Capture, and Recording. The IR camera shall be linked to or include a real-time imaging display. The equipment shall be capable of producing an electronic copy of the IR image(s) to use for evaluation and documentation purposes.
16、 If a dynamic thermal evaluation is required to monitor thermal changes over time or operation conditions, it is recommended that a digital image recording system be used. This allows an entire sequence of a transient event to be captured and allows the procedure to be repeatedly played back after t
17、he evaluation for detailed analysis or documentation purposes. It is recommended that the system microphone, if available, be used by the equipment operator to provide a running narrative during the procedure. The narrative can be used to flag the start of the evaluation, timing of condition changes
18、, and document observations or comments. This audio commentary is beneficial when reviewing or analyzing the evaluation. 3.2.5.3 IR Image Processing Systems. Infrared image processing systems are recommended for situations involving thermal evaluations of complex components or when highly accurate e
19、valuations or highly detailed report documentation is required. 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 GMW8288 Copyright 2012 Gener
20、al Motors Company All Rights Reserved July 2012 Page 3 of 38 An IR imaging processing system typically consists of a general-purpose personal computer equipped with an IR camera interface and IR image processing software. These systems allow enhanced analysis of an infrared evaluation in real-time o
21、r during recording playback. Typical features of image processing systems include: Image zooming. Thermal Image color scale adjustments to improve image resolution. Automated image comparison and display windows that allow the temperatures of operator-defined points to be displayed and tracked in ei
22、ther text or analog graphics display formats. Printouts of selected images complete with captions, scaling, and graphs for report documentation. The makers of the IR camera typically can provide either camera-compatible complete image processing systems or the appropriate add-on equipment to upgrade
23、 a general purpose personal computer into an IR image processing system. IR camera manufacturers can also provide the interface specifications for acquiring an imaging processing system or equipment from third party vendors. 3.3 Test Vehicle/Test Piece. The thermal evaluation procedures defined in t
24、his document are intended to be flexible and adaptable for use in Development, Design Validation, Product Validation, and current product evaluation. Test samples used for development may range from breadboard or other forms of concept demonstrations to actual production samples. Test samples used f
25、or Design Validation shall be production-intent design and materials. Test samples used for Product Validation shall be manufactured on production tooling, with production materials and processes. Test samples used for current product evaluations shall be from normal production lots. 3.4 Test Time.
26、Test time will vary based on the number and types of evaluations required, as well as the setup required, for each test. Setup for each evaluation will involve preparations for the measurement instrumentation, simulation of power and loads, and fixturing/orientation of the test sample. 3.5 Test Requ
27、ired Information. The test requester shall complete a Thermal Evaluations Worksheet (see Appendix B) and provide this to the test facility. The purpose of the Thermal Evaluations Worksheet is to provide detailed instructions to the test facility regarding the measurement method, data to be collected
28、, fixturing/orientation of the test sample, electrical loading, and other test-specific information to be used during the evaluation. 3.6 Personnel/Skills. 3.6.1 General. Knowledge of the applicable thermal measurement methods and equipment. 3.6.2 IR Specific Operator Certification. It is recommende
29、d that the thermographer performing IR imaging shall be trained and certified to at least an ASNT-TC-1A Level II or equivalent. (ASNT is the American Society of Nondestructive Testing.) 4 Procedure 4.1 Preparation. 4.1.1 Preparation (General). 4.1.1.1 Measurement Method Determination. Determine whic
30、h thermal measurement method (i.e., Thermocouple or Infrared Thermography) is needed for the goals of the evaluation. Thermocouple measurement is used to measure the thermal response of specific circuits, areas, or parts on the circuit board or component. The thermocouple must be attached to that sp
31、ecific point of interest, such that the thermal measurement will be localized at that specific point. Thermocouple measurement is used to determine if the point of interest is self-heating as expected or if it is overheating beyond performance or material requirements. Also, this is recommended as a
32、 thermal measurement method in instances where areas of interest are not accessible by Infrared Thermography methods. Infrared Thermography is used to locate, measure, and visualize the thermal gradient response and identify the high stress hot spots of the component as it undergoes various operatin
33、g conditions. Thermography can be used to assess issues related to current flow and material integrity by means of tracking the heat signature during these conditions. Thermography also provides the ability to detect the following: thermal overstress design issues, faulty or failed parts/components,
34、 inadvertent current leakages, and thermal performance changes caused by other overstress, wear out aging mechanisms, or short circuit conditions. (Refer to Appendix D for further information.) Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo
35、 reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW8288 Copyright 2012 General Motors Company All Rights Reserved July 2012 Page 4 of 38 4.1.1.2 Component Test Interface. The component shall be connected to the actual or simulated vehicle interfa
36、ces and loads required to operate the component as per the CTS. The GM Design Release Engineer (DRE) or Product Development Team (PDT) shall define load extremes or variation conditions appropriate to the component at the temperature limits if not defined in the CTS. Adequately sized wiring and fusi
37、ng to handle the worst-case current load shall be used. 4.1.1.3 Component Mounting Orientation. If applicable, the component shall be mounted in an orientation necessary to perform and evaluate any mechanical or visual interface functions. If the component is expected to internally self-heat (10 C o
38、r more at the maximum required operating temperature), it shall be mounted in its in-vehicle orientation or, for the situation of multiple vehicle applications, the worst-case thermal orientation. Note: Thermal worst-case orientation is when the heat dissipated from high powered internal parts is al
39、lowed to rise, flow over, or be trapped around more thermally sensitive parts. 4.1.1.4 Operating Performance Measurements. Appropriate, calibrated instruments shall be used to measure and verify the performance of the component. Sufficient data shall be collected to document proper electrical perfor
40、mance during the thermal evaluations. For power dissipation and self-heating evaluations, the voltage and current of the power supply, key power outputs, and any input/output needed to calculate component power dissipation shall be measured and documented as defined by the PDT for key activation and
41、 loading conditions during the thermal evaluation. E/E components which also perform mechanical, audio, and/or visual/display functions shall be instrumented/monitored as appropriate for the application to measure, record and verify the operation of these functions in accordance with their CTS requi
42、rements, as defined by the PDT. 4.1.1.5 Functional and Thermal Measurements Implementation. The supplier or organization responsible for performing the thermal evaluation is responsible for developing the specific test script and the means for performing the functional, electrical, and thermal measu
43、rements deemed relevant for the component by the PDT. These procedures are to be approved by General Motors (GM) prior to testing. 4.1.1.6 Thermal Evaluations Determination and Worksheet. Refer to the subsections in Section 4.3 for guidelines to determine which thermal evaluations and methods are re
44、quired for the component. These sections provide the typical evaluation objective for vehicular E/E components in the Purpose, Background, Applicability, Procedure, and Criteria for each test. Additional requirements may be defined in the CTS of the component to be tested. The GM DRE or PDT shall re
45、view these objectives against the requirements and design features of the component. The Thermal Evaluations Worksheet (refer to example in Appendix B) shall be used to document which thermal evaluations are required for the component. Place an “X“ or checkmark in the table to denote each procedures
46、 setup, component configuration, and evaluation objective as selected by the PDT. Use a separate copy of the table for each selected evaluation. This worksheet shall be included as part of each tests documentation. 4.1.2 Preparation for Thermocouple Measurements. 4.1.2.1 Thermocouple Measurements Re
47、quirements. Thermal data shall be collected by means of an automated data logger (preferred) or strip chart at a rate of at least three (3) times per minute. The number and types of component internal parts or materials to be temperature-monitored shall be determined by the PDT. Monitoring selection
48、s shall be based on the function and criticality of the component and the circuit designers knowledge of the expected points of high power dissipation. As a minimum, the following thermal measurements are recommended and should be included if deemed appropriate by the PDT: a. Chamber Air Temperature
49、 to monitor the temperature of the air surrounding the component. b. Component Internal Air Temperature for enclosed or partially enclosed components (preferably near the center of the component, microprocessors, or any analog signal circuits of the component). c. Part Temperature(s) of the following as determined by the PDT: Microprocessor(s) Integrated Circuits (IC) High Power Resistors Power driver transistors, Insulated Gate Bipolar Transistors (IGBT)
