1、_SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising theref
2、rom, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions.Copyright 2016 SAE InternationalAll rights reserved. No part of this publi
3、cation may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE.TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada)Tel: +1 724-776-4970 (out
4、side USA)Fax: 724-776-0790Email: CustomerServicesae.orgSAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on thisTechnical Report, please visithttp:/standards.sae.org/AS6171/8AEROSPACESTANDARDAS6171/8Issued 2016-10Techniques for Suspect/Counterfeit EEE Parts Detection by Ra
5、man Spectroscopy Test MethodsRATIONALEThis document is intended to provide guidance for those unfamiliar with Raman spectroscopy towards its use for detection of counterfeit EEE parts. Additionally, it is intended to provide guidelines for the application of Raman spectroscopy for operators and end
6、users of the technique and to define the compliance requirements for laboratories using this technique.INTRODUCTIONRaman spectroscopy is sensitive to vibrations within molecules, much like the more commonly encountered Fourier Transform Infrared (FTIR) spectroscopy (discussed in AS6171/9), and is us
7、ed for the identification of materials. Raman spectra are very similar to FTIR spectra and interpretation is almost identical. A major difference between the two is band intensities (strong bands in the infrared spectroscopy tend to be weak in Raman spectroscopy and vice versa). The spectrum is ofte
8、n compared to a “fingerprint” in that, at least in theory, all Raman active materials produce unique spectra. As a result, sample spectra can be compared to known authentic part reference spectra for verification of identity or compared to databases for identification of the Device Under Test (DUT).
9、 As such this is a very useful method to answer questions such as:1. Is the DUT packaging composed of the specified materials (polymers and fillers)?2. Is the marking ink consistent with original markings or have other inks been applied during repackaging of a counterfeit?3. Are impregnated blasting
10、 materials present (a method used in counterfeiting to resurface a DUT)?4. Has the DUT been exposed to foreign materials such as cleaners?SAE INTERNATIONAL AS6171/8 Page 2 of 17TABLE OF CONTENTS1. SCOPE 32. REFERENCES 32.1 Applicable Documents 32.1.1 SAE Publications. 32.1.2 ASTM Publications 32.1.3
11、 Other Publications. 32.2 Terms and Definitions . 32.3 Acronyms 33. EQUIPMENT AND OTHER SUPPLIES 44. TEST SAMPLE . 44.1 Sample Limitations 45. MATERIALS HANDLING, STORAGE, AND SAMPLE PREPARATION 46. DESCRIPTION OF METHODOLOGY 56.1 Spectral Resolution. 56.2 Laser Wavelength and Response. 56.3 Laser W
12、avelength and Fluorescence . 56.4 Dispersive versus FT-Raman Spectroscopy. 66.4.1 Dispersive Spectrometers. 76.4.2 FT-Raman Spectrometers. 76.5 Confocal Microscopy. 76.6 Laser Wavelength and Differential Detector Response 87. CONTROLS AND CALIBRATION 98. ANALYSIS AND INTERPRETATION OF DATA. 108.1 Ma
13、terial Analysis - Comparison of DUT Spectra to Known Authentic Parts. 108.2 Material Analysis - Comparison of DUT Spectra to Spectra Based on Part Specifications . 128.3 Contamination Analysis. 139. REPORTING OF RESULTS . 1310. QUALIFICATION AND CERTIFICATION . 1410.1 Personnel Qualification . 1410.
14、1.1 Level 3 - Advanced Interpretation (Typically a Chemist) 1410.1.2 Level 2 - Basic Interpretation (Typically a Technician) . 1510.1.3 Level 1 - Operation (Typically an Operator) 1510.2 Safety 1511. NOTES 1511.1 Revision Indicator 15APPENDIX A EXAMPLE OF APPLICATION OF RAMAN SPECTROSCOPY TO COUNTER
15、FEIT DETECTION 16FIGURE 1 SAMPLE FLUORESCENCE AS A FUNCTION OF LASER WAVELENGTH. 6FIGURE 2 GENERIC SPECTROMETER. 6FIGURE 3 CONFOCAL RAMAN MICROSCOPY 8FIGURE 4 POLYSTYRENE SPECTRA . 9FIGURE 5 EXAMPLES OF SIMILAR MATERIALS PRODUCING NEARLY IDENTICAL SPECTRA . 11TABLE 1 REQUIRED TEST REPORT INFORMATION
16、. 14SAE INTERNATIONAL AS6171/8 Page 3 of 171. SCOPETo define capabilities and limitations of Raman spectroscopy as it pertains to counterfeit detection of EEE parts and suggest possible applications to these ends. Additionally, this document outlines requirements associated with the application of R
17、aman spectroscopy including: Operator training; Sample preparation; Data interpretation; Computerized spectral matching including pass/fail criteria; Equipment maintenance and; Reporting of data. If AS6171/8 is invoked in the contract, the base document, AS6171 General Requirements shall also apply.
18、2. REFERENCES2.1 Applicable DocumentsThe following publications form a part of this document to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other publications shall be the issue in effect on the date of the purchase order. In the event of co
19、nflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has beenobtained.2.1.1 SAE PublicationsAvailable from SAE International, 400 Com
20、monwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or +1 724-776-4970 (outside USA), www.sae.org.AS6171 Test Methods Standard: General Requirements, Suspect/Counterfeit Electrical, Electronic, and Electromechanical Parts2.1.2 ASTM PublicationsAvailable from ASTM In
21、ternational, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org.ASTM E131 Terminology Relating to Molecular SpectroscopyASTM E1840 Standard Guide for Raman Shift Standards for Spectrometer CalibrationASTM E2529 Standard Guide for Testing the Resol
22、ution of a Raman Spectrometer2.1.3 Other PublicationsANSI/ESD S20.20 Protection of Electrical and Electronic Parts, Assemblies and EquipmentIDEA-STD-1010 Acceptability of Electronic Components Distributed in the Open MarketIPC/JEDEC J-STD-020 Moisture/Reflow Sensitivity Classification for Nonhermeti
23、c Solid State Surface Mount DevicesIPC/JEDEC J-STD-033 Handling, Packing, Shipping and Use of Moisture/Reflow Sensitive Surface Mount DevicesJESD-625 Requirements for Handling Electrostatic Discharge Sensitive (ESD) Devices2.2 Terms and DefinitionsAll terms that require definition are defined in the
24、 paragraph in which they are first used.2.3 AcronymsSee 2.3 of AS6171 General Requirements.SAE INTERNATIONAL AS6171/8 Page 4 of 173. EQUIPMENT AND OTHER SUPPLIESWhile a variety of Raman spectrometer designs are available, ranging from low end handheld systems to very complicated research oriented; o
25、nly the most common will be discussed. The most typically encountered Raman spectrometers are either Fourier Transform Raman (FT-Raman), stand-alone or as an accessory of an FTIR system, or dispersive. Both types of spectrometer use lasers to excite the samples of interest for collection of spectra;
26、 FT-Raman spectrometers are usually single laser near-IR at 1064 nm while dispersive systems may be equipped with several different wavelength lasers. The most common designs of both types are equipped with rejection filters which block the incident laser light from reaching the detector. 4. TEST SA
27、MPLETest samples can take the form of liquids or solids. Raman spectroscopy offers the advantage of being able to analyze most of these samples with little to no sample preparation. In essence the main requirement is that the sample interface with probes, microscopes, or other sampling accessories o
28、f the spectrometer. On occasion some sample removal and manipulation will be needed.4.1 Sample LimitationsNot all materials are suitable for analysis using Raman spectroscopy. One of the more common problems encountered is sample fluorescence which can overwhelm spectra. This phenomenon is both mate
29、rial and laser wavelength dependent and is typically impossible to predict. When this occurs, the DUT can either be photo bleached by exposing it to the laser for a period of time prior to analysis, or an alternate wavelength laser can be utilized to overcome this. Although not a common feature of m
30、ost Raman spectroscopy systems, if pulsed lasers (nanoseconds-picoseconds) are available, a gated detector that collects the signal only during the laser pulse incidence can significantly suppress background fluorescence, which typically decays on a timescale that is long compared to the laser pulse
31、 duration.Dark colored DUTs typically are problematic as the shifted light that is produced by the Raman effect may be absorbed by the DUT which can greatly reduce the light sent to the detector. This can be overcome by either laser attenuation, defocusing the laser, or selecting an alternate wavele
32、ngth. Although not a common feature of most Raman spectroscopy systems, an alternative configuration to mitigate sample reabsorption uses grazing incidence excitation with laser incidence at an angle 60 to 75 degrees from the surface normal. This configuration can more selectively probe the layers n
33、ear the sample surface.Since the laser concentrates a large amount of energy in a small area, sample burning is a possibility. This can be overcome by laser attenuation and selection of alternate wavelength lasers. Molecules with strong permanent dipole moments (water, glass, etc.) tend to produce a
34、 very weak Raman response. This is because the Raman scattering intensity is proportional to the square of the induced dipole moment (which is proportional to the square of the polarizability). While this is a limitation it is also an advantage if such materials are present but not ofinterest (abili
35、ty to sample through glass for example).5. MATERIALS HANDLING, STORAGE, AND SAMPLE PREPARATIONESD sensitive items shall be handled from receipt to delivery in accordance with ANSI/ESD S20.20 or JESD 625. Moisture sensitive items shall be handled from receipt through delivery in accordance with the r
36、equirements of IPC/JEDEC J-STD-20 and J-STD-033. Refer to the requirements in 3.9.5 of AS6171 General Requirements.NOTE: IDEA-STD-1010 Sections 7.1 and 7.3 provide workstation guidelines.All materials, including samples and sample preparation and analysis devices, shall be handled according to best
37、lab practices, as applicable (i.e., care taken not to contaminate samples, clean work areas and equipment, etc.). In most cases DUTs should be placed into the spectrometer without manipulation. In cases where samples need to be removed from DUTs (background interferences, bulk sample will not fit in
38、to spectrometer, etc.) the minimal sample manipulation needed to prepare a sample shall be applied.SAE INTERNATIONAL AS6171/8 Page 5 of 176. DESCRIPTION OF METHODOLOGYWhen materials are exposed to monochromatic light a number of physical phenomena may occur. For example, it is common that most of th
39、e light is elastically scattered - that is the light is reflected at the same wavelength as the incident beam (Rayleigh scattering). However, about one in a million photons are scattered at a wavelength that is shifted from the incident beam. These shifted photons are what account for the Raman effe
40、ct. They may be either longer wavelength (Stokes) or shorter wavelength (Anti-Stokes) than the incident beam. For most purposes analysis of Stokes shifts alone are considered and will be the focus of this test method.The spectra are plotted as Raman intensity versus Raman shift (cm-1). Raman shift i
41、s usually plotted, by convention, as ZDYHQXPEHUZKLFKLVWKHQXPEHURIFFOHVSHUXQLWG LVWDQFHDQGKDVWKHXQLWVRIUHFLSURFDOFHQWLPHWHUV . Raman spectra are commonly plotted as wavenumber shifts relative to the incident radiation source. Therefore, spectra collected using different wavelength sources contain ban
42、ds at the same relative Raman shifts. Raman spectra look very much like infrared absorbance spectra. Because the Raman effect is dependent upon vibrational states of molecules, the appearance of bands in the Raman correspond to the same vibrational transitions in the infrared. This makes analysis of
43、 spectra a smooth transition for an operator well versed in infrared spectral analysis.6.1 Spectral ResolutionA range of frequency resolution, usually expressed in units of cm-1 (wavenumbers), is available on commercial instruments. These resolutions vary from very low, for example handheld devices,
44、 to very high (i.e., triple grating dispersive systems). For the purposes of counterfeit detection the system shall have a minimum of 16 cm-1 resolution capability.6.2 Laser Wavelength and ResponseThe choice of laser wavelength must take into account the tradeoffs associated with intensity and fluor
45、escence that are wavelength dependent. The intensity of the Raman response is proportional to the 4th power of the frequency of the incident radiation. One can calculate the ratio of response intensities for two lasers by taking the ratio of the fourth power of theircorresponding frequencies: Respon
46、se intensity (Laser 1 / Laser 2) = (frequency of Laser 1)4 / (frequency of Laser 2)4For example, lasers having the following wavelengths produce light having the following frequencies:Laser 1: 532 nm wavelength = 5.63 x 1014 Hertz frequencyLaser 2: 785 nm wavelength = 3.82 x 1014 Hertz frequencyLase
47、r 3: 1064 nm wavelength = 2.82 x 1014 Hertz frequencyThe ratio of intensity between Laser 1 (532 nm) and Laser 2 (785 nm) = (5.63 x 1014 Hz)4 / (3.82 x 1014 Hz)4 = 4.7. Therefore, the intensity of response from a 532 nm laser is 4.7 times higher than that of a 785 nm laser.Similarly, the ratio of in
48、tensity between Laser 1 (532 nm) and Laser 3 (1064 nm) = (5.63 x 1014)4 / (2.82 x 1014)4 = 15.9. The response from a 532 laser is about 16x that of a 1064 nm laser.6.3 Laser Wavelength and FluorescenceWhile shorter wavelength lasers produce stronger relative Raman responses, they may also produce si
49、gnificantly higher fluorescence backgrounds that at times may completely obscure the Raman spectrum. This results from the fact that exposure to shorter wavelengths may excite materials above fluorescence energy levels making such relaxation pathways more favorable than the Raman effect. Figure 1 illustrates a
