I E C 61 -5-50 ® Edition 201 7-05 I N TE RN ATI ON AL S TAN D ARD colour i n sid e Tes t m eth od s for el ectri cal m ate ri al s, pri n te d board an d oth e r i n tercon n e cti on s tru ctu res an d ass em bl i es – P art 5-50 3: G en e ral tes t m eth od for m ate ri al s an d ass em bl i es – C on d u cti ve IEC 61 89-5-503:201 7-05(en) an od i c fi l am e n ts (C AF ) te s ti n g of ci rcu i t board s T H I S P U B L I C AT I O N I S C O P YRI G H T P RO T E C T E D C o p yri g h t © I E C , G e n e v a , S wi tz e 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 I EC copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or your local I EC 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 Ab ou t th e I E C The I nternational Electrotechnical Commission (I EC) is the leading global organization that prepares and publishes I nternational Standards for all electrical, electronic and related technologies Ab o u t I E C p u b l i ca 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 Catal og u e - webstore i ec ch /catal og u e 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 I E C pu bl i cati on s s earch - www i ec ch /search pu b 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variety of criteria (reference number, text, technical committee,…) It also gives information on projects, replaced and withdrawn publications E l ectroped i a - www el ectroped i a org The world's leading online dictionary of electronic and electrical terms containing 20 000 terms and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 G l os sary - s td i ec ch /g l oss ary 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 Pu bl i s h ed - webstore i ec ch /j u stpu bl i sh 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 I E C C u stom er S ervi ce C en tre - webstore i ec ch /csc 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 61 -5-50 ® Edition 201 7-05 I N TE RN ATI ON AL S TAN D ARD colour i n sid e Te s t m eth od s for el ectri cal m ate ri al s, pri n ted board an d oth e r i n tercon n ecti on s tru ctu res an d ass em bl i e s – P art 5-50 3: G en e ral tes t m eth od for m ate ri al s an d ass em bl i e s – C on d u cti ve an od i c fi l am e n ts (C AF ) tes ti n g of ci rcu i t board s INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 31 80 ISBN 978-2-8322-4320-6 Warn i n g ! M ake s u re th a t you ob tai n ed th i s p u b l i cati on from an au th ori zed d i stri b u tor ® Registered trademark of the International Electrotechnical Commission –2– I EC 61 89-5-503: 201 I EC 201 CONTENTS FOREWORD Scope Norm ative references Terms and definitions Testing condition Standard condition Judgm ent state Specimen Outline of CAF test vehicle design Evaluation design for the glass cloth direction Design between plated through hole (PTH) CAF test board Exam ple A 2 Exam ple B 1 Number of specim ens Equipm ent/Apparatus or m aterial Environm ental test cham ber Measuring equipm ent Power suppl y Current lim iting resistors Connecting wire 6 Other dedicated fixtures Resistance m easurement method Manual insulation resistance m easurem ent method Automatic insulation resistance measurem ent m ethod Test method Test method selection Stead y-state temperature and hum idity test Object 2 Test condition Temperature and hum idity (1 h + h) cycle test Object Test condition 3 Number of cycles of the test Temperature and hum idity cyclic test with and without low tem perature exposure Object Test condition Stead y-state high tem perature and high hum idity (unsaturated pressurized vapour) test Object Test condition Procedure Test specim en preparation General Sample identification I EC 61 89-5-503: 201 I EC 201 –3– Prescreen for opens and shorts Cleaning 9 Connecting wire 9 Cleaning after attachment 9 Dry 9 Precondition 9 Test procedure 9 Setting of the specim en 9 Test voltage and m easuring voltage 9 3 Tem perature and humidity condition at the start time of the test 20 Measurement 20 Procedure in test interruption 21 End of test 21 Visual inspection 21 General 21 Shape of electrochem ical m igration 21 Annex A (informative) Form s of electrochemical migration 22 A Example of dendrite-shaped m igration 22 A CAF (Exam ple of m igration along the glass fibre) 22 Bibliograph y 23 Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Table Table Table Table Table Table Table – Schematic of in-line test comb, with possible failure site – Schematic of staggered test com b, with possible failure site – Manhattan distance – Schematic section of via pair with bias – Exam ple of inner layer via pads and layer patterns – Exam ple of no inner layer via pads and layer patterns – I nsulation evaluation pattern for through-holes and via holes 1 – Layouts of the two versions of the CAF test boards – Measurement with insulation resistance meter – Temperature and humidity in a test 20 A – Example which is generated on the board surface 22 A – Example of CAF 22 – Dimension of insulation evaluation pattern for through-holes 1 – Test structures A1 through A4 design rules – Test structures B1 through B4 design rules – Test condition – N um ber of cycles of the test – Test condition – Test condition (I EC 60068-2-66) –4– I EC 61 89-5-503: 201 I EC 201 INTERNATI ONAL ELECTROTECHNI CAL COMMISSI 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 AR D AN D O T H E R I N T E R C 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 -5 : G e n e l te s t m e t h o d fo r m a t e ri a l s a n d a s s e m b l i e s – C o n d u c ti ve a n o d i c fi l a m e n ts ( C AF ) te s ti n g o f c i rc u i t b o a rd s FOREWORD ) The I nternati on al Electrotechni cal Comm ission (I EC) is a worl d wid e organization for stan dardization com prisin g all n ation al el ectrotechnical comm ittees (I EC National Comm ittees) The object of I EC is to prom ote internati onal co-operation on all questions concerni ng stand ardi zati on in the el ectrical an d electronic fields To this end and in additi on to other acti vities, I EC publish es I nternational Stan dards, Techn ical Speci fications, Technical Reports, Publicly Avail abl e Specifications (PAS) an d Gui des (hereafter referred to as "I EC Publication(s)") Thei r preparation is entrusted to technical comm ittees; any I EC Nati on al Comm ittee interested in the subj ect dealt with m ay partici pate in this preparatory work I nternational, governm ental an d n on governm ental organ izations l iaising with th e I EC also participate i n this preparation I EC collaborates closel y with the I ntern ational Organi zation for Stand ardization (I SO) in accordance with conditions determ ined by agreem ent between th e two organi zati ons 2) The form al decisions or ag reem ents of I EC on tech nical m atters express, as n early as possible, an i nternati onal consensus of opi nion on the rel evant subjects since each technical com m ittee has representati on from all interested I EC N ational Com m ittees 3) I EC Publications have the form of recomm endations for intern ational use an d are accepted by I EC National Com m ittees in that sense While all reasonable efforts are m ade to ensure that th e technical content of I EC Publications is accu rate, I EC cann ot be h eld responsi ble for th e way in which th ey are used or for an y m isinterpretation by an y en d u ser 4) I n order to prom ote intern ational u niform ity, I EC National Com m ittees und ertake to apply I EC Publications transparentl y to the m axim um extent possible i n their national an d regi on al publicati ons Any d ivergence between an y I EC Publication and the correspondi ng national or regi on al publicati on sh all be clearl y in dicated in the latter 5) I EC itself d oes n ot provi de an y attestation of conform ity I n dependent certificati on bodies provi de conform ity assessm ent services and, in som e areas, access to I EC m arks of conform ity I EC is not responsi ble for an y services carri ed out by ind ependent certification bodi es 6) All users shou ld ensure that th ey h ave the l atest editi on of thi s publicati on 7) No liability shall attach to I EC or its directors, em ployees, servants or ag ents inclu din g in divi du al experts an d m em bers of its tech nical com m ittees and I EC Nati onal Com m ittees for any person al i nju ry, property d am age or other dam age of any n ature whatsoever, whether di rect or indirect, or for costs (includ i ng leg al fees) and expenses arisi ng out of the publ ication, use of, or relian ce upon, this I EC Publ icati on or any other I EC Publications 8) Attention is drawn to the N orm ative references cited in th is publ ication Use of the referenced publ ications is indispensable for the correct applicati on of this publication 9) Attention is drawn to the possibility that som e of the elem ents of this I EC Publication m ay be the su bject of patent rig hts I EC shall not be held responsibl e for identifyi ng any or all such patent ri ghts I nternational Standard I EC 61 89-5-503 been prepared by I EC technical comm ittee 91 : Electronics assem bl y technology The text of this standard is based on the following docum ents: FDI S Report on votin g 91 /1 433/FDI S 91 /1 443/RVD Full information on the voting for the approval of this I nternational Standard can be found in the report on voting indicated in the above table This docum ent has been drafted in accordance with the I SO/I EC Directives, Part I EC 61 89-5-503: 201 I EC 201 –5– 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 I EC website The com mittee has decided that the contents of this document 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 docum ent At this date, the document will be • • • • reconfirmed, withdrawn, replaced by a revised edition, or amended A bilingual version of this publication m ay be issued at a later date I M P O RT AN T th at it – Th e co 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 of ' co l ou r c o l o u rs i ts i n si de' wh i ch c o n te n ts l og o a re U s e rs on th e cover c o n s i d e re d sh ou l d p ag e to t h e re fo re of th i s be p ri n t p u b l i cati on u s e fu l th i s fo r i n d i c ate s th e d ocu m e n t c o rre c t u si n g a –6– I EC 61 89-5-503: 201 I EC 201 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 AR D AN D O T H E R I N T E R C 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 -5 : G e n e l te s t m e t h o d fo r m a t e ri a l s a n d a s s e m b l i e s – C o n d u c ti ve a n o d i c fi l a m e n ts ( C AF ) te s ti n g o f c i rc u i t b o a rd s S cop e This part of I EC 61 89 specifies the conductive anodic filament (hereafter referred to as CAF) and specifies not onl y the stead y-state temperature and hum idity test, but also a temperaturehum idity cyclic test and an unsaturated pressurized vapour test (H AST) N o rm a t i ve re fe re n c e s The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this docum ent For dated references, onl y the edition cited applies For undated references, the latest edition of the referenced docum ent (includin g an y am endm ents) applies I EC 60068-1 : 201 3, Environmental testing – Part 1: General and guidance IEC 60068-2-30, Environmental testing – Part 2-30: Tests – Test Db: Damp heat, cyclic (12 h + 12 h cycle) IEC 60068-2-38, Environmental testing – Part 2-38: Tests – Test Z/AD: Composite temperature/humidity cyclic test IEC 60068-2-66, Environmental testing – Part 2: Test methods – Test Cx: Damp heat, steady state (unsaturated pressurized vapour) I EC 60068-2-67, Environmental testing – Part 2: Tests – Test Cy: Damp heat, steady state, accelerated test primarily intended for components I EC 60068-2-78, Environmental testing – Part 2-78: Tests – Test Cab: Damp heat, steady state I EC 601 94, Printed board design, manufacture and assembly – Terms and definitions IPC-TM-650 N o 2.6 , Electrochemical Migration Resistance Test [viewed 2017-01-31] Available at: https://www ipc org/TM/2-6_2-6-14-1 pdf IPC-TM-650 N o 25, Conductive Anodic Filament (CAF) Resistance Test: X-Y Axis [viewed 2017-01-31] Available at: https://www ipc org/4 0_Knowledge/4 1_Standards/test/2-6-25 pdf T e rm s a n d d e fi n i t i o n s For the purposes of this docum ent, the term s and definitions given in I EC 601 94 and I EC 60068-1 as well as the following appl y I SO and I EC m aintain term inological databases for use in standardization at the following addresses: I EC 61 89-5-503: 201 I EC 201 –7– • I EC Electropedia: available at http://www electropedia.org/ • I SO Online browsing platform : available at http://www iso.org/obp 3.1 electrochemical migration degradation of insulation characteristics between conductors due to eletrochemical elution of ions in a hum id environment when voltage is applied to conductors of a printed wiring board Note to entry: I n ad dition, i onic im purities present in th e i nsulations contri bute to thei r d egradation Note to entry: El ectrochem i cal m igration m ay take th e form s of dend rite (3 2) an d CAF(3 3) 3.2 dendrite metal migration Note to entry: Dend rite is visibl e in that it creates a branching an d tree l ike structu re on th e su rface, on th e interface between layers, etc of a pri nted wi rin g board 3.3 CAF conductive anodic filament migration which occurs along the monofilam ent of reinforcing material such as glass cloth in an inner layer part of a printed wiring board 3.4 HAST highly accelerated temperature and humidity stress test stress test under unsaturated pressurized vapour test Note to entry: See I EC 60068-2-66 3.5 automatic insulation resistance measurement measurement to take continuous or predetermined periodic test data using an automatic measurement system without an operator 3.6 manual insulation resistance measurement measurement to take predetermined periodic test data using m easurement equipm ent by an operator Note to entry: Measurem ent can be d one with or without taking out a specim en from the test cham ber 3.7 test voltage voltage to appl y on the specim en as a stress in the testing environment 3.8 measuring voltage voltage to appl y on the specimen in order to measure the insulation resistance Testing condition 4.1 Standard condition Measurement is perform ed under the standard atm ospheric condition which is specified in Clause of I EC 60068-1 : 201 –8– I EC 61 89-5-503: 201 I EC 201 It depends on a reference condition stated in when an ambiguity is found for the j udgm ent in the standard atm ospheric condition or when it is required in particul ar It may be performed under other conditions than the standard atmospheric condition, when no doubt about the judgm ent subsits and when m easuring in standard condition proves difficult, or when specified in particular specifications 4.2 Judgment state Reference condition is the standard atm ospheric condition for measurement as stated in 4.2 of I EC 60068-1 :201 Specimen 5.1 5.1 Outline of CAF test vehicle design Evalu ation design for the glass cloth direction The in-line test combs are comprised of a series of alternate rows of via holes with a voltage applied across the comb They represent the most comm on failure sites where CAF can occur: between via hole walls The via holes are in line with one another and in alignm ent with th e woven glass fibre reinforcem ent The closest point between each via pair is the most likel y point for CAF growth (exam ple highlighted in Figure ) The black spots represent the drilled hole, and the copper pads associated with the via holes are in orange The construction of staggered com bs is sim ilar to that of the in-line combs, however, the via pairs are arranged at 45° This m eans that the most likel y route for potential CAF growth is longer since the orientation of the glass fibres may onl y perm it growth in the horizontal and vertical directions (as represented by the white ellipses in Figure 2) Fibre weave IEC Figure – Schematic of in-line test comb, with possible failure site – 12 – I EC 61 89-5-503: 201 I EC 201 perpendicular to the rows of same-net daisy chain vias for A1 to A4 (machine/grain direction tends to fail first) Test board designs shall have sufficient m inim um spacings on outer layers to ensure that surface insulation resistance failures not occur Layouts of the I PC-9253 and I PC-9254 test board structures (CAF test boards) are shown in Figure The test board design rules are listed in Table and Table A1 A2 A3 A4 B1 B2 B3 B4 C1 C2 C3 C4 D1 D2 A1 A2 A3 A4 B1 B2 B3 B4 C1 C2 C3 C4 D1 D2 Area of PTH s for test wi re attachm ent Area of PTH s for test wi re attachm ent IEC IEC a) I P C -9 53 b ) I P C -9 F i g u re – L a y o u t s o f t h e t w o v e rs i o n s o f t h e C AF t e s t b o a rd s T a b l e – T e s t s t ru c t u re s A1 A1 t h ro u g h A4 d e s i g n ru l e s A2 A3 A4 Outer l ayer pad size 0, 86 m m (0, 033 i n) 0, 81 m m (0, 031 i n) 0, 75 m m (0, 029 i n) 0, 69 m m (0, 027 i n) I nner l ayer pad size 0, 86 m m (0, 033 i n) 0, 81 m m (0, 031 i n) 0, 75 m m (0, 029 i n) 0, 69 m m (0, 027 i n) Drill ed hol e size 0, 74 m m (0, 029 i n) 0, 63 m m (0, 024 i n) 0, 51 m m (0, 020 i n) 0, 37 m m (0, 025 i n) Via edge to via edg e (sh ortest distance) 0, 27 m m (0, 01 i n) 0, 38 m m (0, 01 i n) 0, 51 m m (0, 020 in ) 0, 65 m m (0, 025 i n) Via edge to via edg e (Manh attan distance) 0, 27 m m (0, 01 i n) 0, 38 m m (0, 01 i n) 0, 51 m m (0, 020 i n) 0, 65 m m (0, 025 i n) On I PC-9254 on ly, bias applied between: J1 , J5 J 2, J J 3, J J 4, J I EC 61 89-5-503: 201 I EC 201 – 13 – Table – Test structu res B1 through B4 design ru les B1 B2 B3 B4 Outer l ayer pad size 0, 94 m m (0, 037 i n) 0, 89 m m (0, 035 i n) 0, 84 m m (0, 033 i n) 0, 75 m m (0, 030 i n) I nner layer pad size 0, 94 m m (0, 037 i n) 0, 89 m m (0, 035 i n) 0, 84 m m (0, 033 i n) 0, 75 m m (0, 029 i n) Drill ed hol e size 0, 81 m m (0, 031 i n) 0, 71 m m (0, 028 i n) 0, 57 m m (0, 022 i n) 0, 46 m m (0, 01 i n) Via edge to via edg e (sh ortest distance) 0, 26 m m (0, 01 i n) 0, 37 m m (0, 01 i n) 0, 51 m m (0, 020 in ) 0, 62 m m (0, 024 i n) Via edge to via edg e (Manh attan Distance) 0, 37 m m (0, 01 i n) 0, 52 m m (0, 020 i n) 0, 72 m m (0, 028 i n) 0, 88 m m (0, 034 i n) On I PC-9254 on ly, bias applied between: J 7, J 1 J 8, J 1 J 9, J 1 J 0, J 1 5.3 Number of specimens Num ber of specim ens, test boards or coupons required in a test depends on the purpose of the test, for exam ple for prototypes or for m ass produced products For CAF testing of circuit boards for m ass production, a m inim um quantity of 25 is needed for statistical reliability anal ysis More than 25 specimens may be needed for a test lot in order to provide at least as many opportunities-for-failure as a single production board (see I PC-9691 B) Equipment/Apparatus or material 6.1 Environmental test chamber a) A clean test cham ber capable of producing and recording an environm ent of 65 °C ± °C or 85 °C ± °C at 87 °C ± % RH, and that is equipped with cable access to facilitate m easurement cables to be attached to the specim ens under test b) The temperature and hum idity in the cham ber can be continuously supplied and not reused, and independently controlled to prevent condensation c) Hum idification water in the cham ber can be continuousl y supplied and not reused d) The condensation water does not drop from the wall and the ceiling in the cham ber e) I m purities and the residual substances of the previous test shall be rem oved so as to not affect the test f) The cham ber should be made of the m aterials which not have an y influence on the specim en and humidification water 6.2 M easuring equipment A high resistance m eter equivalent to that described in ASTM D257, with a range up to 1 Ω and capable of yielding an accuracy of ±5 % at 1 Ω with a DC applied voltage of 00 V ± V, or an amm eter capable of reading − A and capable of yi elding an accuracy of ±5 % in com bination with 00 V ± V DC power supply The values of resistors used shall be verified by reference resistors traceable to known industry or national standards 6.3 Power supply A power supply capable of producing a standing bias potential of V DC up to 00 V DC with a ±2 % tolerance, and current supply capacity of at least A – 14 – 6.4 I EC 61 89-5-503: 201 I EC 201 Current limiting resistors Tight control of the total current lim iting resistance value is critical for this test method M Ω resistor in series shall be used for each current path I nsert the current lim iting resistors in series with the terminating leads going to each test pattern N ote that some test equipm ent has current lim iting resistors built into the testing systems For the purposes of this standard test, excluding the current lim iting resistor and for each CAF test circuit, the total series resistance of the m easuring equipm ent and wires shall not be more than 200 Ω A lower total resistance value will increase potential for damage to the test board when a CAF failure occurs A higher total current lim iting resistance value for each test net rem oves test conditions further from actual field conditions and is not recommended 6.5 Connecting wire Use PTFE- or PFE-insulated copper wires and solder the copper wire directl y to the board to connect test points for each test board to the m easurement apparatus 6.6 Other dedicated fixtures Hard-wiring is the default connection method Other dedicated fixtures m ay be used, provided that the fixture does not change the resistance by more than 0, decade com pared to a comparable hard-wired system when measured at the test conditions These fixtures should be checked for their resistance values frequently The colour of the leads connected to plus and minus electrodes of the measuring equipment should be changed Usuall y red is used for the cable connected to the plus term inal and black to the minus term inal Resistance measurement method 7.1 Manual insulation resistance measurement method The resistance measuring unit can m easure the resistance range of Ω to 1 Ω Figure illustrates an example of a manual measuring system in the chamber, using an insulation resistance meter This m easuring system has a built-in power source, can select the test voltage and the measuring voltage arbitrary, and is capable of resistance m easurem ent of up to 1 Ω using double shielded cables and a shielded test cham ber I EC 61 89-5-503: 201 I EC 201 – 15 – IEC Ke y guard insulati on resistance m eter active guard dou ble shi eld cable power su ppl y cham ber Fi g u re – M easu rem en t wi th i n su l ati on resi stan ce m eter Au tom ati c i n su l ati on resi stan ce m easu rem en t m eth od The insulation resistance generall y decreases as temperature and relative hum idity increase The volume resistance is sensitive to the change of the tem perature, but the surface resistance changes rapidl y with the change of the relative humidity As for both cases, the change is exponential Since insulation resistance is dependent on both volume resistance and surface resistance, it is necessary to hold tem perature and humidity to the specified values as m uch as possible For this reason, it is desirable to perform the measurem ent of insulation resistance within the cham ber (m easurem ent in the chamber) I n taking out the specimen from the chamber to measure, the time to shift to room tem perature (measurem ent conditions) and leaving tim e in the room tem perature should be decided I n principle, this m easurement shall be made within 24 h The condition other than stated here should be provided in an individual specification The autom atic insulation resistance equipm ent can control automaticall y the applied voltage and measurem ent by a computer, and generate an alarm when anomal y is generated in the m easurement without taking out the specimen under test from the test cham ber The test voltage is applied to each specim en and leak electric current is monitored so that the generation and tim e of electrochem ical migration can be m easured precisel y Tests of man y specim ens can be carried out efficientl y A test should be continued when such phenom ena as a m om entary low resistance state or a temporary short in the measurem ent using an autom atic insulation resistance m easurement equipm ent not occur frequentl y – 16 – I EC 61 89-5-503: 201 I EC 201 Test m eth od Tes t m eth o d s el e cti o n The ECM test method is used as a lifetim e evaluation test of substrate m aterials and electronic parts and acceptance test at the order source The form er is requi red to obtain the tim e to failure, which is the standard for calculating the useful life I n the latter, the tem perature/hum idity condition, the applied voltage, and the test time are determined, and the process is com pleted in a predeterm ined tim e Selection of the various ECM test methods described here is left to the user 8 S tead y-s tate tem p e ratu re an d h u m i d i ty tes t O bj ect This test is im plemented to ensure or verify the ability to maintain the service life if the specim en is used under constant temperature and hum idity conditions This test is an accelerated test which is set at a higher tem perature and hum idity than when the specim en is used I t is im portant that linearity can be achieved for the Arrhenius plot obtained from the fault tim e to tem perature changes to evaluate the lifetim e I f the linearity is not obtained, it is necessary to review the test conditions and to pay sufficient attention to high tem perature conditions On the basis of the results of the life test, the test conditions of the confirm ation test are determined Tes t d i ti o n The stead y-state tem perature and hum idity test conditions follows in Table These m ay be used in the absence of an y defined test specification Test condition of temperature/hum idity is specified in I EC 60068-2-78 and I EC 60068-2-67 except 60 ºC/90 % RH , which is added as one of the temperature hum idity stead y-state conditions because it has been used as one of the standard environmental test conditions for the integrated circuits Tabl e – Te s t d i ti o n S p eci fi c ati o n STD I PC-TM-650 (2 25) I PC-TM-650 (2 ) 8 Te m p era tu re H u m i di ty Te s t ti m e °C % RH h 40 ± 93 ± 60 ± 90 ± 85 ± 85 ± 65 ± 87+ 3/ − 85 ± 40 ± 93 ± 65 ± 88, ± 3, 85 ± 88, ± 3, 68 −0 ＋ 24 500 ± 48 000 ± 96 (2 000 ± 92) – Test boards to stabili ze for 96 h (±30 m in) After the 96 h (±30 m in) stabil i zation peri od, insu lation resistance m easurem ents shall be m ade between each daisy ch ain n et an d g rou nd – Additional tem peratu re/h um idity/bias conditionin g m ay be perform ed after 500 h of bi as, som etim es up to 000 h or m ore Tem pe ratu re an d h u m i d i ty ( h + h ) cycl e te s t O bj ect This test exam ines the insulation degradation, resistance to electrochem ical m igration, and other perform ance degradations for printed wiring boards under the h + h cyclic dam p heat condition with an applied voltage to the specim en in which dew is generated on the surface I EC 61 89-5-503: 201 8.3.2 I EC 201 – 17 – Test condition The h + h cyclic damp heat test condition is specified in I EC 60068-2-30 8.3.3 Number of cycles of the test The com bination of the upper temperature an d the number of cycles define the severity of the test The upper temperature and the num ber of cycles shall be chosen from Table Table – Number of cycles of the test Condition Upper temperature Number of cycles a) 40 °C 5, 0, 20, 30, (50) b) 55 °C 5, 0, 20, (30) Condition a) or b) shall be selected based on i ndi vid ual specifications 8.4 8.4.1 Temperature and humidity cyclic test with and without low temperature exposure Object This test evaluates the resistance of the board to electrical insulation degradation and resistance to migration under the temperature and humidity cyclic test with and without low temperature exposure I t is an effective test to confirm the durability of the products in environments with varying temperature and hum idity 8.4.2 Test condition The test condition for the stead y-state tem perature and humidity test is given in Table unless there is an y additional condition Table – Test condition 1) The test conditi on of tem peratu re/h um idity is specified i n I EC 60068-2-38 2) Test severities: cycles 3) Tol erance for tem peratu re: ±2 ºC (in cham ber) 4) Tol erance for relati ve hum idity: ±3 % RH (d uring th e peri ods constant or risi ng tem peratu re) 80 % to 96 % RH (d uri ng th e falling tem peratu re) 5) Test severities (unl ess ten cycles): depen din g on i ndi vi dual specification 6) Measuri ng tim e: depen din g on indi vid ual specification 7) Test voltage: d epend ing on in d ivid ual specification 8) Measuri ng voltage: depen din g on in dividu al specificati on 8.5 8.5.1 Steady-state high temperature and high humidity (unsaturated pressurized vapour) test Object This test enables an accelerated evaluation of insulation deterioration of material by forced moisture absorption, resistance to migration, comparison of material characteristics, lot reliability, moisture proof reliability for insulating film (solder resist, etc.) and other performance degradations – 18 – I EC 61 89-5-503: 201 I EC 201 This test enables the evaluation of material characteristics in a short time I t was originall y developed to assess semiconductor devices in a package N ote that the relation between the glass transition tem perature of an organic resin and the test temperature has an important influence on the estimated lifetim e I f the acceleration factor of lifetim e between this test method and the actual operating condition is not clear, this test method is suitable for test comparison purposes, but may not be used as a guarantee for the material T es t d i ti o n Unless a specific condition is specified, the test condition shall be selected from the conditions given in Table 7, which is specified in I EC 60068-2-66 However, the application of Table depends on individual specifications Tab l e – T e s t d i ti o n ( I E C 0 -2 -6 ) T e s t t e m p e t u re H u m i di ty Te s t ti m e V a p o u r p re s s u r e °C % RH h MPa 110 ± 85 ± 96, 92, 408 –0 0, 20 ± 85 ± 48, 96, 92 ~ 0, 30 ± 85 ± 24, 48, 96 +2 0, 23 1) The testin g tim e represents the test end tim e and d oes not m ean the tim e to extract the test specim en 2) The testin g voltag e is selected between V DC and 00 V DC 3) The m easuri ng voltage is selected between V DC an d 00 V DC 4) I tem s to be specified by i ndi vi d ual specificati on a) Different ditions from this test conditions and severity of the specified dition (m andatory) b) I nitial m easurem ent (m andatory) c) J ig to be used for the test P ro c e d u re 9 Test speci m en p re p a t i o n G e n e l A specimen is inspected using a m agn ifying glass with a to 0× m agnification Check observable foreign materials, for exam ple extraneous coppers, peeling of solder resist, grim es, and the condition of the surface of metal plating I f an y defects are found, the specimen should not be used in the testing S a m p l e i d e n t i fi c a t i o n Use a method to identify each test board which does not cause contamination, such as a scribe and making marks away from the biased area(s) of the specimen Test boards shall be handled by the edges of the board onl y, and the use of non-contaminating gloves is recomm ended P re s c re e n fo r o p e n s a n d s h o rt s Perform as-received insulation resistance measurem ents using a m ultimeter by connecting to each net, and check for gross defects Check for shorts at a , M Ω setting N o opens are allowed in connected nets I EC 61 89-5-503: 201 9.1 I EC 201 – 19 – Cleaning Clean the specimen with water or alcohol to rem ove dirt, dust and adhered flux Set the specim en in the chamber and start the test without handling, packaging or storage which m ay affect the test result 9.1 Connecting wire Use PTFE- or PFE-insulated copper wires and solder, and appl y the copper wire directl y to the board to connect test points for each test board to the measurement apparatus Cover the test board with non-contam inating film to prevent flux spattering during the wire attach process Ensure that PWB lam inate m aterial adjacent to the plated holes does not get dam aged during soldering by using appropriate tim e/temperature param eters for the soldering iron 9.1 Cleaning after attachment Perform appropriate local cleaning and rinsing after the attachment of the connecting wires Isolation resistance between connecting wire attachm ent sites should remain excellent during 96 h conditioning N ote that each CAF test failure that occurs during subsequent testing should be checked, to determine whether the connecting wire attach area is the low resistance site I f the connecting wire attach area rather than the daisy chain area is the low insulation resistance site, then that test sam ple is no longer valid for data anal ysis 9.1 Dry Bake sam ple boards for h in a clean oven at (1 05 ± 2) °C 9.2 Precondition Precondition test board sam ples in a bias-free state (no electrical potential applied to an y test pattern) for 24 h m inim um at (23 ± 2) °C and (50 ± 5) % relative humidity prior to an y initial insulation resistance measurements (measuring insulation resistance of each daisy-chain net on each test board before starting the first 96 h (±30 min) of bias-free temperature and hum idity conditioning) 9.3 9.3.1 Test procedure Setting of the specimen a) The ventilation direction and a specim en side should be parallel The specimen m ay be from the ceiling of the cham ber or is put up with a test fixture Specimens should be installed in parallel to the air flow direction wind and be separated mm or m ore so that the air flow in the chamber may not be disturbed b) Avoid cable routing and dips which m ay allow condensed water to drop on the test specimen c) Specim ens should not be placed close to the heat source and wall of a cham ber The working space where the specified testing conditions can be controlled within specified tolerance is specified in I EC 60068-3-5 9.3.2 Test voltage and measuring voltage a) The recomm ended voltage range of test and m easuring voltage is V DC to 00 V DC The voltage range exceeding this range may be used depending on individual specification b) The test voltage and the measuring voltage shall always have the same polarity, and as a general rule shall be assum ed to have the same DC voltage value c) For tests of multilayer boards the method to suppl y test voltage between each layers depends on individual specifications – 20 – 3 T e m p e t u re a n d h u m i d i t y c o n d i ti o n I EC 61 89-5-503: 201 I EC 201 a t t h e s t a rt t i m e o f t h e t e s t Temperatu re a) First the temperature is raised and then the humidity is increased with a suitable tim e lag, as shown in Figure 0, so as to avoid dew formation on the surfaces of the specimen and the wall in the chamber b) The test voltage should be applied as soon as the cham ber is in stable condition Applied test T1 Humidity Tim e T3 Applied test T2 Tim e T1 ≤ × T2 30 m in ≤ T1 ≤ 60 m in m in ≤ T3 ≤ 30 m in T3 : Stability tim e IEC F i g u re – T e m p e t u re a n d h u m i d i ty i n a te s t c) The starting condition of the test is shown in Figure in the case of a stead y-state test d) The cycle test condition depends on the individual specification e) Application of a test condition other than specified here, is described in the individual specification 9 M e a s u re m e n t I n i ti al m e a s u re m e n t a) After observing the specimen visuall y or using a m agnifying glass with a to 0× magnification according to 4, the m easurem ent of the insulation resistance shall be carried out b) The insulation resistance of the test board in standard condition shall be confirmed to be m ore than 1 Ω , but it should be larger than 1 Ω if phenol resin is used When the resistance is stated in an individual specification, observe the resistance I n t e rm e d i a t e m e a s u re m e n t Checks shall be carried out to ensure data being measured using automatic insulation resistance m easurement equipm ent The test may be interrupted and output data should be checked in detail if necessary Fi n al m e a s u re m e n t The specimen is taken out of the cham ber as soon as the temperature in the chamber is back to room tem perature at the end of the test I EC 61 89-5-503: 201 I EC 201 – 21 – The visual inspection of a specim en with a m agnifying glass with a to 0× m agnification is executed according to The insulation resistance m easurement is carried out under the standard atm ospheric condition according to A fault anal ysis should be made if necessary Observe an y condition if specified in individual specifications 9.3.4.4 Evaluation criteria A failure should be recorded if the resistance becom es less than Ω in case of m easurement inside of the chamber, or less than Ω in case of measurement outside of the cham ber 9.3.5 Procedure in test interruption a) I f the test is interrupted, the specim en is carefull y handled to avoid ) handling of the specim en with bare hands, 2) storing in a place which has a large tem perature/humidity difference to the test environm ent, and 3) adhesion of dirt and dust b) During a test interruption the period when the environm ental conditions are not stable should not be included in the test time 9.3.6 End of test The test is finished after the prescribed examination time I f test ends with the m alfunction of the test equipment or abnormal insulation resistance, this status is recorded clearl y in order to obtain an y required information for later analysis 9.4 9.4.1 Visu al inspection General The inspection process is described below For effective observations ensure the illumination of the sample allows for viewing of both of reflectance and transmission com ponents of the light 9.4.2 Shape of electrochemical migration Representative shapes of m igration are shown in a) and b) and photographs are also included in Annex A a) Shape A (see Figure A ): The observed exam ple that dendrite-shaped m igration occurred on the board surface b) Shape B (see Figure A 2): CAF (an exam ple of m igration along the glass fibre) – 22 – I EC 61 89-5-503: 201 Annex A (informative) Forms of electrochemical migration A.1 Example of dendrite-shaped migration IEC Specim en: the FPC wh ich di d Sn-Pb surface finishi ng of copper patterns Pattern gap is 0, mm Test condition: water d ropped m ethod: V DC appli ed Figu re A.1 – Example which is generated on the board surface CAF (Example of migration along the glass fibre) Surface Plated through hol e A.2 Between through-holes IEC Figure A.2 – Example of CAF I EC 201 I EC 61 89-5-503: 201 I EC 201 – 23 – Bibliography I EC 60068-3-4, Environmental testing – Part 3-4: Supporting documentation and guidance – Damp heat tests I EC 60068-3-5, Environmental testing – Part 3-5: Supporting documentation and guidance – Confirmation of the performance of temperature chambers I EC 60721 -1 , Classification of environmental conditions – Part 1: Environmental parameters and their severities I EC 60721 -2-1 , Classification of environmental conditions – Part 2-1: Environmental conditions appearing in nature – Temperature and humidity I EC 60721 -3-0, Classification of environmental conditions – Part 3: Classification of groups of environmental parameters and their severities – Introduction IEC TR 62866, Electrochemical migration in printed wiring boards and assemblies – Mechanisms and testing ASTM D257, Standard Test Methods for DC Resistance or Conductance of Insulating Materials IPC-TM-650 No 9, Environmental and Insulation Resistance Test of Hybrid Ceramic Multilayer Substrate Boards IPC-9691 B, User Guide for the I PC-TM-650, Method 2.6 25, Conductive Anodic Filament (CAF) Resistance and Other Internal Electrochemical Migration Testing _ 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