ECA-SP-5179-2009.pdf

10 march 2009 subject: standards proposal no. 5179, proposed new tp-112, eia-364-112 “test procedure for determining the contact resistance and current rating of parallel circuits in an electrical connector or socket.” (if approved, to be published as ansi/eia-364-112). background: at the october 2008 meeting, the ce-2.0 national connector and socket standards committee authorized circulation of the document for sp balloting. sp-5179 is herewith submitted to the ce-2.0 membership for voting and for ansi public review and other interested parties for comment as steps towards standardization. if this sp ballot receives insufficient ballot returns, the committee chairman may place it on the formulating committee agenda as an item up for vote at its next stated meeting. once the sp is placed on the agenda, those members not able to attend the scheduled meeting and wishing to vote must submit their vote to eca prior to that meeting. please provide the following information whether voting or commenting via public review. number each comment whether it is either editorial and/or technical. company name - comment no. type of comment - technical or editorial reference - page no., clause no., line suggested change - change from:. to:. add:, delete: rationale for technical change for purpose of committee vote: voting period expires may 11, 2009 for purpose of public review: comment period expires may 11, 2009 prior to this date, you may forward your comments to the designated eia contact noted below. following the expiration of the comment period, this standards proposal will be submitted to the eia technology strategy fax: 703-875-8908; email: comment period expires: may 11, 2009 each comment submission should indicate either: _i am providing the attached technical comments concerning standardization of the contents of sp-5179 as an american national standard, and recommend that the attached, along with the reason(s) for making the recommendation, be considered by the ce-2.0 committee. _i am providing the attached editorial comments concerning standardization of the contents of sp-5179 as an american national standard, and recommend that the attached, along with the reason(s) for making the recommendation, be considered by the ce-2.0 committee. date _ name _ (please print) tel:_ name _ (signature) e-mail:_ company _ _ address _ _ copyright electronic components, assemblies & materials association provided by ihs under license with eca licensee=hp monitoring/1111111164 not for resale, 04/09/2009 03:45:50 mdtno reproduction or networking permitted without license from ihs -,-,- copyright electronic components, assemblies & materials association provided by ihs under license with eca licensee=hp monitoring/1111111164 not for resale, 04/09/2009 03:45:50 mdtno reproduction or networking permitted without license from ihs -,-,- notice this document is an eia engineering standards proposal, rather than an interim or final standard. it is published for purposes of comment and is subject to further review and modification by the eia engineering department executive committee (edec), which may accept or reject the standards proposal. accordingly, readers of this standards proposal are cautioned against relying on information contained therein prior to the adoption of a final standard. eia disclaims any liability or responsibility for the consequences of such reliance. published by electronic components association 2009 eia standards and technology department 2500 wilson boulevard suiter 310 arlington, va 22201 all rights reserved printed is u.s.a. iii preliminary - subject to revision. do not specify or claim conformance to this document. copyright electronic components, assemblies & materials association provided by ihs under license with eca licensee=hp monitoring/1111111164 not for resale, 04/09/2009 03:45:50 mdtno reproduction or networking permitted without license from ihs -,-,- contents clause page 1 introduction 1 1.1 scope 1 1.2 object 1 1.3 background 1 1.4 prerequisites 2 2 definitions 2 3 test method 2 3.1 method a, central limit theorem parallel contact resistance 2 3.2 method b (reserved for future use) 3 4 details to be specified 3 5 test documentation 4 table a.1 test groups a-1 a.2 test results a-2 a.3 monte carlo simulation results a-3 a.4 histogram results a-4 a.5 distribution of parallel resistance means results a-6 a.6 unit-to-unit variation relative to the pin-to-pin variation a-7 annex a method a, example central limit theorem parallel contact resistance (informative) a-1 a.1 test sequences a-1 a.2 results a-2 a.3 validation a-3 a.4 histogram results a-4 a.5 discussion a-4 a.6 implementation a-7 a.7 summary a-8 a.8 notes a-8 iv preliminary - subject to revision. do not specify or claim conformance to this document. copyright electronic components, assemblies & materials association provided by ihs under license with eca licensee=hp monitoring/1111111164 not for resale, 04/09/2009 03:45:50 mdtno reproduction or networking permitted without license from ihs -,-,- (this page left blank) v preliminary - subject to revision. do not specify or claim conformance to this document. copyright electronic components, assemblies & materials association provided by ihs under license with eca licensee=hp monitoring/1111111164 not for resale, 04/09/2009 03:45:50 mdtno reproduction or networking permitted without license from ihs -,-,- test procedure no. 112 contact resistance and current rating of parallel circuits test procedure for electrical connectors and sockets (from eia standards proposal no. 5179, formulated under the cognizance of eia ce-2.0 committee on national connector standards) 1 introduction 1.1 scope this procedure applies to connectors and sockets when multiple circuits are electrically connected in a parallel configuration and there is a need to determine the expected parallel resistance and or current rating. 1.2 object 1.2.1 this standard establishes a procedure for determining the predicted parallel contact resistance of a connector or socket when multiple circuits are connected in parallel. a statistical approach is employed to determine the parallel or effective contact resistance using empirical data from eia connector test sequences such as eia-364-1000. 1.2.2 the procedure for determining current rating of a connector or socket when multiple circuits are connected in parallel will be added in the near future to this document. 1.3 background traditional methods for determining low level contact resistance limits for parallel circuits such as a worst case parallel resistance calculation employ extremely conservative calculations that produce limits unlikely to be seen in actual application. this procedure outlines a more realistic method that is based on sound statistical principles and determines the parallel resistance limit with a percentile derived from calculations made using easily-obtained data. the limit calculated by this standard may be used by system designers to plan their voltage drop budget. unrealistically high limits calculated with the previous method result in inefficient use of power resources in an application. method a applies the central limit theorem to parallel resistance distributions. 1 preliminary - subject to revision. do not specify or claim conformance to this document. copyright electronic components, assemblies & materials association provided by ihs under license with eca licensee=hp monitoring/1111111164 not for resale, 04/09/2009 03:45:50 mdtno reproduction or networking permitted without license from ihs -,-,- 1.4 prerequisites the proposed methods are not a substitute for common connector qualification practices. these methods rely upon said qualification test data. in such tests, a maximum resistance and/or a maximum delta resistance limit will be applied to individual contact data. it is not appropriate the apply theses methods to products with open circuits or high resistances that do not meet these criteria. connector products that do not meet these criteria should not be considered qualified for use in an application based solely upon its calculated parallel resistance. the connectors must meet a clear individual contact limit before a parallel resistance is calculated. 2 definitions 2.1 parallel circuit two or more connector or socket circuits electrically connected together on both sides of the separable interface. 2.2 central limit theorem a mathematical theorem that is central to the use of statistics. it states that for a random sample of observations from any distribution with a finite mean and a finite variance, the mean of the observations will follow a normal distribution. this theorem is the main justification for the widespread use of statistical analyses based on the normal distribution. 3 test method 3.1 method a, central limit theorem parallel contact resistance see annex a for an example and additional information. 3.1.1 identify the end-of-life low level contact resistance measurements, r, for each stress group in a typical connector qualification test. calculate the mean (r) and standard deviation (sr) of the distribution of r for each test group. 3.1.2 determine the number of contacts (n) in the parallel circuit for the connector of interest. 3.1.3 calculate the expected parallel resistance (pr) through the connector of interest using the following formula. n r rp 2 preliminary - subject to revision. do not specify or claim conformance to this document. copyright electronic components, assemblies & materials association provided by ihs under license with eca licensee=hp monitoring/1111111164 not for resale, 04/09/2009 03:45:50 mdtno reproduction or networking permitted without license from ihs -,-,- 3.1.4 consideration may be given to analyzing the data per the actual use case. the computations for rp would use the exact contact positions planned in the final application. alternately, if other contacts in the product are identical to those used in the final application, then that data could also be utilized. 3.1.5 use the following formula to calculate the expected parallel resistance standard deviation (sp), found by applying the central limit theorem. nn s s r p 3.1.6 per the central limit theorem, assume the distribution of pr is normal. 3.1.7 calculate the percentile of interest using pr and sp and normal probability according to the following formula. p pszrp+= 99 3.1.8 the value of z comes from a z-table. for the 99th percentile, z = 2.326. for a more conservative calculation, a t-table may be used rather than a z-table. when a t-table is used, the degrees of freedom equals n 1. 3.2 method b (reserved for future use) 4 details to be specified the following details shall be specified in the referencing document: 4.1 analysis method to be used 4.2 end of life contact resistance data for each test sequence from a connector qualification test program such as eia-364-1000 (see the annex(s) for an example) 3 preliminary - subject to revision. do not specify or claim conformance to this document. copyright electronic components, assemblies & materials association provided by ihs under license with eca licensee=hp monitoring/1111111164 not for resale, 04/09/2009 03:45:50 mdtno reproduction or networking permitted without license from ihs -,-,- 5 test documentation documentation shall contain the details specified in clause 4, with any exceptions, and the following: 5.1 title of test 5.2 test equipment used, and date of last and next calibration 5.3 results of the analysis (see the annex(s) for an example) 5.4 name of operator and start/finish dates of test 4 preliminary - subject to revision. do not specify or claim conformance to this document. copyright electronic components, assemblies & materials association provided by ihs under license with eca licensee=hp monitoring/1111111164 not for resale, 04/09/2009 03:45:50 mdtno reproduction or networking permitted without license from ihs -,-,- annex a method a, example central limit theorem parallel contact resistance (informative) the following data illustrates the method using data from a sample of 25 fb dimm parts, divided into five groups and subjected to the following stress tests: a.1 test sequences table a.1 test groups test group test or examination a b c d e 1 low level contact resistance 1,4,6 1,4,6,8 1,3,5,7 1,4,6,8,10 1,4,6,8 2 durability 2 2 2 2 2 3 temperature life 3 4 thermal shock 3 5 physical shock 6 6 random vibration 4 7 cyclic temperature &humidity 5 8 reseating 5 7 9 7 9 mixed flowing gas 5 10 thermal cycling 5 11 thermal disturbance 7 12 temperature life (preconditioning) 3 3 specimen quantity (pieces) 5 5 5 5 5 notes 1 group c did not compete testing on all contacts. 2 the data included here is for those contacts on which testing was completed. a-1 preliminary - subject to revision. do not specify or claim conformance to this document. copyright electronic components, assemblies & materials association provided by ihs under license with eca licensee=hp monitoring/1111111164 not for resale, 04/09/2009 03:45:50 mdtno reproduction or networking permitted without license from ihs -,-,- a.2 results the method produces the results given below for circuits using 4, 22, and 59 contacts in parallel. table a.2 test results group number of data points (readings) r srn (number of contacts in parallel) pr sp99th %tile a 1200 7.4409 1.0617 4 1.86022 0.13272 2.16891 b 1200 7.7255 0.714 4 1.93136 0.08925 2.13895 c 290 5.7362 0.4641 4 1.43406 0.05801 1.56900 d 1200 7.0192 0.5723 4 1.75479 0.07153 1.92118 e 1200 7.676 0.7201 4 1.91900 0.09001 2.12836 a 1200 7.4409 1.0617 22 0.33822 0.01029 0.36215 b 1200 7.7255 0.714 22 0.35116 0.00692 0.36725 c 290 5.7362 0.4641 22 0.26074 0.00450 0.27120 d 1200 7.0192 0.5723 22 0.31905 0.00555 0.33195 e 1200 7.676 0.7201 22 0.34891 0.00698 0.36514 a 1200 7.4409 1.0617 59 0.12612 0.00234 0.13157 b 1200 7.7255 0.714 59 0.13094 0.00158 0.13460 c 290 5.7362 0.4641 59 0.09722 0.00102 0.09961 d 1200 7.0192 0.5723 59 0.11897 0.00126 0.12191 e 1200 7.676 0.7201 59 0.13010 0.00159 0.13380 a-1 preliminary - subject to revision. do not specify or claim conformance to this document. copyright electronic components, assemblies & materials association provided by ihs under license with eca licensee=hp monitoring/1111111164 not for resale, 04/09/2009 03:45:50 mdtno reproduction or networking permitted without license from ihs -,-,- a.3 validation a.3.1 a monte carlo simulation can validate the results given above. the simulation method uses bootstrapped data points from the original raw data set with replacement. for a simulation meant to validate a 4-pin circuit, the simulation randomly selects 4 readings from a single stress group. the simulation calculates the parallel resistance of these 4 points and saves it. the simulation repeats this until 2,500 parallel resistances for the given pin count and stress group have been calculated. a.3.2 the monte carlo simulations produced the results given below. the percentile here is the actual percentile from the simulated parallel resistances, not a calculation based on the mean and standard deviation of those resistances. the is the difference between the prediction percentile given in the formulaic method above and the simulation percentile. table a.3 monte carlo simulation results group simulations n pr sp99th %tile a 2500 41.831330.128602.15800 0.01091 b 2500 41.915690.089842.11717 0.02178 c 2500 41.428080.052401.57970 -0.01070 d 2500 41.746970.071201.91877 0.00241 e 2500 41.909380.086092.13530 -0.00694 a 2500 220.332130.009510.35617 0.00598 b 2500 220.348030.007070.36431 0.00294 c 2500 220.259310.004030.26997 0.00123 d 2500 220.317110.005420.32952 0.00243 e 2500 220.346210.006430.36226 0.00288 a 2500 590.123730.002130.12894 0.00263 b 2500 590.129830.001570.13336 0.00125 c 2500 590.096660.000800.09866 0.00095 d 2500 590.118200.001220.12094 0.00096 e 2500 590.129050.001450.13260 0.00120 a-1 preliminary - subject to revision. do not specify or claim conformance to this document. copyright electronic components, assemblies & materials association provided by ihs under license with eca licensee=hp monitoring/1111111164 not for resale, 04/09/2009 03:45:50 mdtno reproduction or networking permitted without license from ihs -,-,- a.4 histogram results the charts below graphically depict the results. the histograms represent the data for each group and pin count. the red lines represent the calculated limit from the prediction percentile. the blue lines represent the actual percentile from the simulations. table a.4 histogram results group raw n = 4 n = 22 n = 59 a 50 100 150 200 250 count .117 .119 .121 .123 .125 .127 .129 .131 50 100 150 200 1.81.9 100 200 300 .7 50 100 150 200 678910 b 100 200 300 .5.36.37 100 200 300 count .3.132.134 100 200 300 22.12.2 50 100 150 200 6789 c 100 200 3