IEC TS 61 1 89 3 301 Edition 1 0 201 6 07 TECHNICAL SPECIFICATION Test methods for electrical materials, printed boards and other interconnection structures and assemblies – Part 3 301 Test methods fo[.]
I E C TS 61 -3 -3 ® Edition 201 6-07 TE C H N I C AL S P E C I F I C ATI ON colour in sid e Tes t m eth od s for el ectri cal m ateri al s , pri n ted board s an d oth er i n tercon n ecti on s tru ctu res an d as s e m bl i es – Part 3-3 : Tes t m eth od s for i n tercon n ecti on s tru ctu res (pri n ted board s ) – IEC TS 61 89-3-301 :201 6-07(en) Appearan ce i n s pecti on m eth od for pl ated s u rfaces on P WB Copyright International Electrotechnical Commission TH I S P U B L I C ATI O N I S C O P YRI G H T P RO TE C T E D C o p yri g h t © I E C , G e n e va , S w i tze rl a n d All rights reserved Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or IEC's member National Committee in the country of the requester If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or your local IEC member National Committee for further information IEC Central Office 3, rue de Varembé CH-1 21 Geneva 20 Switzerland Tel.: +41 22 91 02 1 Fax: +41 22 91 03 00 info@iec.ch www.iec.ch Abou t th e I E C The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes International Standards for all electrical, electronic and related technologies Ab o u t I E C p u b l i c a ti o n s The technical content of IEC publications is kept under constant review by the IEC Please make sure that you have the latest edition, a corrigenda or an amendment might have been published I E C C atal og u e - webs tore i ec ch /catal og u e E l ectroped i a - www el ectroped i a org The stand-alone application for consulting the entire bibliographical information on IEC International Standards, Technical Specifications, Technical Reports and other documents Available for PC, Mac OS, Android Tablets and iPad The world's leading online dictionary of electronic and electrical terms containing 20 000 terms and definitions in English and French, with equivalent terms in additional languages Also known as the International Electrotechnical Vocabulary (IEV) online I E C pu bl i cati on s s earch - www i ec ch /s earch pu b I E C G l os s ary - s td i ec ch /g l os s ary The advanced search enables to find IEC publications by a variety of criteria (reference number, text, technical committee,…) It also gives information on projects, replaced and withdrawn publications 65 000 electrotechnical terminology entries in English and French extracted from the Terms and Definitions clause of IEC publications issued since 2002 Some entries have been collected from earlier publications of IEC TC 37, 77, 86 and CISPR I E C J u st P u bl i s h ed - webs tore i ec ch /j u s u bl i s h ed Stay up to date on all new IEC publications Just Published details all new publications released Available online and also once a month by email Copyright International Electrotechnical Commission I E C C u s to m er S ervi ce C en tre - webs tore i ec ch /cs c If you wish to give us your feedback on this publication or need further assistance, please contact the Customer Service Centre: csc@iec.ch I E C TS 61 -3 -3 ® Edition 201 6-07 TE C H N I C AL S P E C I F I C ATI ON colour in sid e Tes t m eth od s for el ectri cal m ateri al s , pri n ted board s an d oth er i n tercon n ecti on s tru ctu res an d as s em bl i es – P art 3-3 : Tes t m eth od s for i n tercon n ecti on s tru ctu res (pri n ted board s ) – Appearan ce i n s pecti on m eth od for pl ated s u rfaces on PWB INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 31 80 ISBN 978-2-8322-3550-8 Warn i n g ! M ake s u re th at you obtai n ed th i s pu bl i cati on from an au th ori zed d i s tri bu tor ® Registered trademark of the International Electrotechnical Commission Copyright International Electrotechnical Commission –2– I EC TS 61 89-3-301 : 201 I EC 201 CONTENTS FOREWORD Scope Normative references Terms and definitions Test specimens 5 Equipment / apparatus 5 Evaluation of lustre non-uniformity 5 Evaluation of colour non-uniformity 6 Procedure 6 Outline of the method 6 Specimen preparation 6 I maging of surface roughness/chromaticity distribution 6 Binarization of images 6 Extraction of feature quantities 6 Derivation of discriminant function 7 System registration 7 Report 8 Additional information Annex A (informative) Example of equipment and tested result for lustre nonuniformity A Equipment for lustre non-uniformity inspection A Tested result A 2.1 Surface roughness image A 2.2 Binarized image and feature extraction 1 A 2.3 Frequency analysis of feature quantities A 2.4 Final estimate Annex B (informative) Example of tested result for colour non-uniformity inspection B I mage analysis of colour non-uniformity B Feature extraction and discriminant analysis Bibliography Figure – Flow chart of the test procedure Figure A.1 – Equipment prototype Figure A.2 – I mages of gold-plating of non-defective and defective products Figure A.3 – I mages of S- and P- polarized com pon en ts, an d Ψ ’ for g ol d -plating with lustre non-uniformity 1 Figure A.4 – I mage examples of gold-plating with lustre non-uniformity 1 Figure A.5 – Example of frequency analysis of feature quantity Figure A.6 – Example of the final estimate of the quality of gold-plating Figure B.1 – I mages of gold-plating pads Figure B.2 – I mages of colour distribution Figure B.3 – Frequency analysis example of a feature quantity Figure B.4 – Example of the discriminant analysis result Copyright International Electrotechnical Commission I EC TS 61 89-3-301 : 201 I EC 201 –3– I NTERNATIONAL ELECTROTECHNI CAL COMMI SSI ON T E S T M E T H O D S F O R E L E C T RI C AL M AT E RI AL S , P RI N T E D B O ARD S AN D O T H E R I N T E RC O N N E C T I O N S T RU C T U RE S AN D AS S E M B L I E S – P a rt - : T e s t m e t h o d s fo r i n t e rc o n n e c t i o n s t ru c t u re s ( p ri n t e d b o a rd s ) – Ap p e a n c e i n s p e c t i o n m e t h o d fo r p l a t e d s u rfa c e s o n P WB FOREWORD ) The I nternati onal El ectrotechnical Commi ssi on (I EC) is a worl d wi d e organizati on for standard izati on comprisi ng all nati onal electrotech nical committees (I EC N ational Comm ittees) Th e object of I EC i s to prom ote i nternati on al co-operati on on al l q u esti ons cernin g standard izati on i n the el ectrical and el ectronic fi el ds To this end an d in ad di ti on to other acti vi ti es, I EC pu blish es I nternati onal Stan d ards, Technical Speci fi cati ons, Technical Reports, Pu bl icl y Avail abl e Specificati ons (PAS) and Gu id es (hereafter referred to as “I EC Pu blicati on(s)”) Their preparati on is entru sted to technical committees; any I EC N ati onal Committee i nterested i n the subject d eal t with may parti ci pate i n thi s preparatory work I nternati on al , governmen tal and nongovernm ental organizations l iaisi ng wi th the I EC al so participate i n this preparati on I EC coll aborates cl osel y wi th the I nternational Organizati on for Stand ard izati on (I SO) in accordan ce wi th cond i ti ons d etermin ed by agreement between th e two org anizati ons 2) Th e form al decision s or agreem ents of I EC on tech nical matters express, as nearl y as possibl e, an i nternati onal consensus of opi ni on on the rel evan t su bjects si nce each technical committee has representati on from all i nterested I EC N ati onal Commi ttees 3) I EC Pu blications have th e form of recommend ati ons for internati onal u se and are accepted by I EC N ati onal Comm ittees i n th at sense While all reasonabl e efforts are mad e to ensu re that the technical content of I EC Pu blicati ons is accu rate, I EC cann ot be hel d responsi bl e for the way in wh i ch they are used or for an y misin terpretati on by any end u ser 4) I n ord er to promote i nternational u ni formi ty, I EC N ati onal Commi ttees u nd ertake to appl y I EC Pu blicati ons transparen tl y to the maximum exten t possi bl e i n thei r nati onal and reg i onal pu blicati ons An y di verg ence between an y I EC Pu bl icati on and the correspond i ng nati onal or region al publi cation shal l be cl earl y i ndi cated in the l atter 5) I EC i tsel f d oes n ot provi d e any attestation of conformity I nd epend ent certificati on bodies provi d e conformity assessment services an d , in some areas, access to I EC marks of conformi ty I EC i s not responsi bl e for an y services carried ou t by i nd epend en t certi fication bodi es 6) All users sh ould ensu re that they h ave the l atest edi ti on of this pu blicati on 7) N o li abili ty shal l attach to I EC or i ts di rectors, empl oyees, servan ts or agents in clu di ng i nd ivi du al experts and members of i ts technical commi ttees and I EC N ati onal Comm ittees for any personal i nju ry, property d amage or other d amage of any n atu re whatsoever, whether di rect or in d i rect, or for costs (i nclud i ng l egal fees) and expenses arising out of the pu bli cati on, use of, or rel ian ce u pon, thi s I EC Pu bl ication or an y other I EC Pu blicati ons 8) Attention is d rawn to the N ormative references cited i n this pu bl icati on U se of the referenced pu blicati ons is i ndi spensabl e for the correct appli cati on of this publicati on 9) Attention is d rawn to th e possibili ty that some of the el ements of thi s I EC Pu bl icati on may be th e su bject of patent ri ghts I EC sh al l not be held responsi bl e for i d en ti fyi ng any or all su ch patent ri ghts The main task of I EC technical committees is to prepare International Standards I n exceptional circumstances, a technical committee may propose the publication of a technical specification when • • the required support cannot be obtained for the publication of an I nternational Standard, despite repeated efforts, or the subject is still under technical development or where, for any other reason, there is the future but no immediate possibility of an agreement on an International Standard Technical specifications are subject to review within three years of publication to decide whether they can be transformed into I nternational Standards I EC TS 61 89-3-301 , which is a technical specification, has been prepared by I EC technical committee 91 : Electronics assembly technology Copyright International Electrotechnical Commission –4– I EC TS 61 89-3-301 : 201 I EC 201 The text of this technical specification is based on the following documents: En q ui ry d raft Report on voti ng 91 /1 348/DTS 91 /1 376/RVC Full information on the voting for the approval of this technical specification can be found in the report on voting indicated in the above table This publication has been drafted in accordance with the ISO/I EC Directives, Part A list of all parts in the I EC 61 89 series, published under the general title Test methods for electrical materials, printed boards and other interconnection structures and assemblies , can be found on the IEC website The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the I EC website under "http: //webstore iec.ch" in the data related to the specific publication At this date, the publication will be • • • • • transformed into an International standard, reconfirmed, withdrawn, replaced by a revised edition, or amended A bilingual version of this publication may be issued at a later date I M P O R T AN T th a t it – Th e c o n ta i n s u n d e rs t a n d i n g c o l o u r p ri n t e r Copyright International Electrotechnical Commission of 'col ou r c o l o u rs i ts i n si d e' wh i ch co n te n ts l og o a re U s e rs on th e c o ve r p a g e c o n s i d e re d sh ou l d to t h e re fo re o f th i s be p ri n t p u b l i ca ti o n u s e fu l th i s fo r i n d i c a te s th e d ocu m en t c o rre c t using a I EC TS 61 89-3-301 : 201 I EC 201 –5– T E S T M E T H O D S F O R E L E C T RI C AL M AT E RI AL S , P RI N T E D B O ARD S AN D O T H E R I N T E RC O N N E C T I O N S T RU C T U RE S AN D AS S E M B L I E S – P a rt - : T e s t m e t h o d s fo r i n t e rc o n n e c t i o n s t ru c t u re s ( p ri n t e d b o a rd s ) – Ap p e a n c e i n s p e c t i o n m e t h o d fo r p l a t e d s u rfa c e s o n P WB Scope This part of I EC 61 89 outlines a way to determine the appearance non-uniformity of both the lustre and colour on plated metal surfaces in printed wiring boards (PWBs) The method is applicable to gold, nickel and copper plating in PWBs N o rm a t i v e re fe re n c e s There are no normative references in this document T e rm s a n d d e fi n i t i o n s For the purposes of this document, the following terms and definitions apply I SO and I EC maintain terminological databases for use in standardization at the following addresses: • I EC Electropedia: available at http: //www.electropedia org/ • I SO Online browsing platform: available at http: //www iso.org/obp l u s t re n o n - u n i fo rm i t y abnormal roughness distribution in plated surfaces leading to irregular brightness of reflected light 3.2 c o l o u r n o n - u n i fo rm i t y irregular reflection spectrum N ote to en try: Col ou r non -u ni formity i s cau sed by other i nflu ences than rou ghness ch ange, su ch as abnormal compon ents, ad hesi on of foreign matter and oxi d ati on in pl ated su rfaces 4 Te s t s pe ci m en s Specimen dimensions and forms should be in accordance with the test system Specimens of non-defective and of defective products, of several tens to one hundred, at least of ten, are required as teacher data for each series of evaluation 5 E q u i p m e n t / a p p a t u s E va l u a t i o n o f l u s t re n o n - u n i fo rm i t y For the evaluation of the lustre non-uniformity, a test system capable of measuring the surface roughness distribution should be used As for an optical method, CCD (chargeCopyright International Electrotechnical Commission –6– I EC TS 61 89-3-301 : 201 I EC 201 coupled device), or CMOS (complementary metal oxide semiconductor) camera systems, or as for a mechanical method, stylus type tester shall be used, respectively E v a l u a t i o n o f c o l o u r n o n - u n i fo rm i t y For the evaluation of the colour non-uniformity, an optical system capable of measuring the chromaticity distribution shall be used 6 P ro c e d u re O u tl i n e o f th e m e th o d The method is outlined by the flow chart in Figure S p e c i m e n p re p a t i o n I m a g i n g o f s u rfa c e ro u g h n e s s / c h ro m a t i c i t y d i s t ri b u t i o n B i n a ri z i n g o f i m a g e s E x t c t i o n o f fe a t u re q u a n t i t i e s D e ri v a t i o n o f d i s c ri m i n a n t fu n c t i o n S y s t e m re g i s t t i o n IEC Th e nu mbers i nd icate the su bcl ause references F i g u re – F l o w c h a rt o f t h e t e s t p ro c e d u re I n this method, the procedures of the evaluation of lustre non-uniformity and colour nonuniformity are basically the same S p e c i m e n p re p a t i o n Requirements for specimens are specified in Clause I m a g i n g o f s u rfa c e ro u g h n e s s /c h ro m a t i c i t y d i s t ri b u t i o n Acquire the images of surface roughness for the lustre non-uniformity, and/or of chromaticity distribution for the colour non-uniformity, by the apparatus / equipment mentioned in Clause B i n a ri z a t i o n of i m ag es Obtain the binary images by the threshold processing The region giving values significantly deviating from the average value of the whole image concerned is counted to be (white pixels) as abnormal, and the others to be (black pixels) as normal Copyright International Electrotechnical Commission I EC TS 61 89-3-301 : 201 I EC 201 –7– The threshold setting should be agreed upon between the parties 6.5 Extraction of feature quantities Extract the feature quantities of abnormal regions from the binarized images by image analysis of the size, area, shape, and distribution, etc of the irregularities For example, the diagonal length of the minimum rectangles bounding the clusters of abnormal regions, and change in the number of pixels by the binary image contraction of repetition can be used as feature quantities The type and number of feature quantities to be used should be agreed upon between the parties 6.6 Derivation of discriminant function Discriminant analysis shall be performed using the feature quantities extracted from specimens of non-defective and defective products as indicated in 6.5 as the teacher data to split into two groups The linear discriminant function is expressed by Equation (1 ): Z = a + 1 a X + a X2 + a X3 + + a i Xi + (1 ) where Z is the discriminant score; is a constant; a i (subscript) indicates the dimensions of the discriminant function; is the discriminant coefficient as weighting factor for the separation of test specimens of a teacher data into the two groups, non-defective and defective; is the frequency of feature quantities taken into consideration X i i Equation (1 ) is defined to distinguish the group of non-defective specimens from the group of defective specimens by the value Z, which is respectively set to be positive for non-defective and negative for defective specimens by adjusting a , and a i I f necessary, the type of non-linear discriminant function based on Mahalanobis' generalized distance, D may also be used The type of the discriminant function to be used can be agreed upon between the parties 6.7 System registration The resulting discriminant function shall be registered to the test system to perform evaluation of unknown specimens For the unknown specimen, the value of Z shall be calculated using the registered function, which is defined by Equation (1 ) in advance in the linear discriminant analysis From the values of Z obtained, the quality of the unknown specimen can be estimated I n case of a non-linear discriminant function, the values of D shall be used for the estimate of unknown specimens Copyright International Electrotechnical Commission –8– I EC TS 61 89-3-301 : 201 I EC 201 Re port Report the specimen numbers of both non-defective and defective products used as the teacher data 7 Report the apparatus / equipment information for capturing images of plated surfaces in the tested specimens Report the value of threshold for the binarizing images Report the type, stepping width, and range of the feature quantities extracted from the binarized images Report the discriminant function derived for evaluation of the tested specimens Ad d i ti on al i n form ati on An optical method based on the polarization analysis and image recognition has been proposed from AI ST, Japan, and a powerful camera system that can observe both a lustre irregularity and uneven colouring at the same time has been developed 8.2 Examples of the equipment and tested results are shown in Annex A and Annex B Copyright International Electrotechnical Commission I EC TS 61 89-3-301 : 201 I EC 201 –9– Annex A (informative) Example of equipment and tested result for lustre non-uniformity A.1 Equipment for lustre non-uniformity inspection Figure A.1 shows the test equipment prototyped for the lustre non-uniformity H al f mi rror M i rror CCD LEN Z Pol arizer Pol arizer LED (red ) Speci men IEC Figure A.1 – Equipment prototype The incident light that illuminated the sample was linearly polarized and tilted at 45° to have the ratio of /1 for the S-/P-polarized components The reflected light was separated by a half mirror and passed the S and P polarizers for independent imaging by the CCD camera In order to obtain distribution images of the surface roughness, the CCD images captured were analyzed by comparing each pixel of the images of the S- and P-polarized components Mapping of the surface roughness according to the pixel size can be achieved using this method A.2 A.2.1 Tested result Surface roughness image Figure A.2 shows the examples of images of gold-plated pads of non-defective (see a to c) and defective products (see d to l) with various types of lustre non-uniformity in PWBs, captured by a CCD camera Figure A shows the example of surface roughness images analyzed by the equipment of Figure A for gold plating of defective specimens with lustre non-uniformity I mages of Spolarized (see a, d, g), P-polarized (see b, e, h) components, and Ψ’ (see c, f, i), calculated from the ratio of S- to P-polarized components indicate the surface roughness distribution for gold-plating with lustre non-uniformity in PWBs Copyright International Electrotechnical Commission – 10 – I EC TS 61 89-3-301 : 201 I EC 201 IEC F i g u re A – I m a g e s o f g o l d - p l a t i n g Copyright International Electrotechnical Commission o f n o n - d e fe c t i ve a n d d e fe c t i v e p ro d u c t s I EC TS 61 89-3-301 : 201 I EC 201 – 11 – IEC F i g u re A – I m a g e s o f S - a n d P - p o l a ri z e d c o m p o n e n t s , and Ψ’ for gol d - p l a t i n g A wi th l u s t re n o n - u n i fo rm i t y B i n a ri z e d i m a g e a n d fe a t u re e x t c t i o n Figure A.4 a) shows an example of a binarized image of abnormal portions in the series of specimens shown in Figure A and Figure A The threshold for binarization is set as follows: regions giving values within ±1 % of the average value are classified as normal, and those beyond this limit are counted as abnormal (white pixels) Figure A.4 b) shows an example of extraction of feature quantities of abnormal portions using the minimum rectangles bounding the clusters of white pixels The diagonal length of the minimum rectangles is defined as the feature quantity, expressed as L i (a) (b) Li IEC F i g u re A a ) – B i n a ri z e d i m ag e F i g u r e A b ) F i g u re A – I m a g e e x a m p l e s o f g o l d - p l a t i n g w i t h Copyright International Electrotechnical Commission – F e a t u re q u a n ti ty l u s t re n o n - u n i fo rm i t y – 12 – A.2.3 I EC TS 61 89-3-301 : 201 I EC 201 Frequency analysis of feature quantities Figure A shows an example of a frequency analysis of the feature quantities of gold-plating L to obtain each frequency, X i i Freq u ency ( X ) i Featu re qu anti ty ( L ) i IEC Figure A.5 – Example of frequency analysis of feature quantity A.2.4 Final estimate Figure A shows an example of the linear discriminant analysis result using specimens of gold-plating of non-defective and defective products as the teacher data to determine the quality of the object specimens corresponding to boundary specimens 20 15 10 N on -d efective Teacher d ata Z Defective –5 –1 Obj ect specim en –1 –20 IEC Figure A.6 – Example of the final estimate of the quality of gold-plating As shown in Figure A.6, Z of a non-defective product takes a value above 0, in the range +5 to +1 I n contrast, Z of a defective product takes a value below 0, in the range –2 to –1 Using this function, Z of an unknown (object) specimen is evaluated to be 7, and this result estimates the specimen as non-defective, and the judgment agrees with that obtained by visual inspection I n this way, the criteria for acceptability can be provided using the discriminant function As a result, objective determination and classification criteria can be obtained for the digitization of the lustre non-uniformity of gold plating Copyright International Electrotechnical Commission I EC TS 61 89-3-301 : 201 I EC 201 – 13 – An n e x B (informative) E xa m p l e o f t e s t e d re s u l t fo r c o l o u r n o n -u n i fo rm i t y i n s p e c t i o n B.1 I m a g e a n a l y s i s o f c o l o u r n o n -u n i fo rm i t y Colour non-uniformity has been analyzed using the ratios of different colour signal settings such as green to red (G/R), blue to green (B/G), and red to blue (R/B) in images captured by a CCD camera for gold-plating pads in defective specimens of PWB Figure B shows an example of a result of colour non-uniformity analysis using the ratio of G/R, which gives the clearest change (comparing to the ratios of B/G and R/B in this experiment) The images of Figure B.1 display the following gold-plating pads (500 μm × 500 μm) G/R a) colour non-uniformity, b) the magnified view, c) and the colour distribution in G/R, with the signal intensity ratio of green to red, as a function of pixel position in a CCD camera Pi xel posi tion IEC F i g u re B – I m a g e s o f g o l d -p l a t i n g pads Figure B.2 shows the examples of images of G/R and threshold images for the same specimen as shown in Figure B I n Figure B b), the regions detected as colour nonuniformity are marked in red Copyright International Electrotechnical Commission – 14 – I EC TS 61 89-3-301 : 201 I EC 201 IEC F i g u re B a) – G /R c o l o u r d i s tri b u t i o n F i g u re B b) – T h re s h o l d i m ag es F i g u re B – I m a g e s o f c o l o u r d i s t ri b u t i o n B.2 F e a t u re e x t c t i o n a n d d i s c ri m i n a n t a n a l y s i s Figure B.3 shows an example of frequency analysis result of the feature quantity extracted from gold-plating with colour non-uniformity as shown in Figure B.2 For the feature quantity, the number of times that the images were contracted is used to count the numbers of pixels remaining in the resulted images This extracting method is found to be suitable comparing to the method using the length of diagonals in roughness mode irregularities shown in Figure A.4 b) The classification of the quality has been performed by visual inspection of skilled testers in advance Freq u ency Figure B illustrates an example of a frequency analysis of the feature quantity of goldplating in non-defective (No.1 -84) and defective specimens (N o 85-1 05) with colour nonuniformity For the feature quantity, the number of times that the images were contracted is used to count the numbers of pixels remaining in the resulting images Featu re qu anti ty N u mber of test specimen IEC F i g u re B – F re q u e n c y a n a l ys i s e x a m p l e o f a fe a t u re q u a n t i t y Copyright International Electrotechnical Commission I EC TS 61 89-3-301 : 201 I EC 201 – 15 – Figure B.4 shows an example of the linear discriminant analysis result for the specimens of gold-plating of non-defective (No.1 -84) and defective specimens (No 85-1 05) with colour nonuniformity The specimens of non-defective products give positive values of Z, while defective ones reveal negative values of Z The specimens are the same as those shown in Figure B.3 250 200 N on-d efective 50 00 Defective Z 50 –50 –1 00 –1 50 –200 –250 20 40 60 80 00 20 N u mber of test specimen IEC Figure B.4 – Example of the discriminant analysis result Copyright International Electrotechnical Commission – 16 – I EC TS 61 89-3-301 : 201 I EC 201 Bibliography [1 ] [2] Kazuhiro Nonaka, Toshihiro Kamohara, Toshiaki Koga, Kazufumi Sakai, and Kousuke Miura, Development of Compact Inspection Apparatus for the Digitization of Nonuniformity in the Luster of Gold Plating , Proceedings of the ECWC1 3, 201 Brian J DeBoo, Jose M Sasian, and Russell A Chipman, Depolarization of diffusely objects , APPLI ED OPTICS, 2005 reflecting man -made _ Copyright International Electrotechnical Commission Copyright International Electrotechnical Commission INTERNATIONAL ELECTROTECHNICAL COMMISSI ON 3, rue de Varembé PO Box 31 CH-1 21 Geneva 20 Switzerland Tel: + 41 22 91 02 1 Fax: + 41 22 91 03 00 info@iec.ch www.iec.ch Copyright International Electrotechnical Commission