SAE EIA-554A-1996 Method Selection for Assessment of Nonconforming Levels in Parts Per Million (PPM) (Formerly TechAmerica EIA-554 SET).pdf

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4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/EIA554A TECHNICAL REPORT EIA-554 REV. A Revised 1996-07 Reaffirmed 2002-09 Method

5、 Selection for Assessment of Nonconforming Levels in Parts Per Million (PPM) NOTICE This document has been taken directly from the original TechAmerica document and contains only minor editorial and format changes required to bring it into conformance with the publishing requirements of SAE Technica

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8、standard format. TechAmerica Standard Method Selection for Assessment of Nonconforming Levels in Parts Per Million (PPM) EIA-554-A August 1996 EIA-554-ANOTICE TechAmerica Engineering Standards and Publications are designed to serve the public interest by eliminating misunderstandings between manufac

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12、ndard or Publication. This TechAmerica Standard is considered to have International Standardization implications, but the ISO/IEC activity has not progressed to the point where a valid comparison between the TechAmerica Standard and the ISO/IEC document can be made. This Standard does not purport to

13、 address all safety problems associated with its use or all applicable regulatory requirements. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations before its use. (From Standard Propo

14、sal No. 4959, formulated under the cognizance of the TechAmerica Quality and Reliability Engineering (QRE) Committee) Published by 2011 TechAmerica Standards nonconforming units are removed if found. The action resulting from an audit is taken on the process that produced the material. 5.3 average o

15、utgoing quality (AOQ) - The average proportion nonconforming components, in parts per million, from a series of lots. 5.4 proportion nonconforming - The unknown proportion nonconforming of the total population of components. Estimates of proportion nonconforming are derived from samples. 5.5 inspect

16、ion - The assessment of a characteristic and its comparison to a standard. Examples of inspections include low temperature electrical test, room temperature test, visual inspection. 5.6 lot - An aggregate of components produced under essentially the same set of conditions from which the sample is ra

17、ndomly drawn. 5.7 nonconformance - A component characteristic that does not conform to an individual specified criterion. 5.8 nonconforming component - A single component that has one or more nonconformances. These nonconforming components may be placed into classes for reporting purposes. 5.9 parts

18、 per million (PPM) - The unit of measurement used to describe the quality of manufactured product, giving an average number of nonconforming components for each million units. 5.10 sample period - The period of time selected by the manufacturer to accumulate data for the calculation and reporting of

19、 PPM. EIA - 554A Page 3 6.0 ASSUMPTIONS The methods described herein are primarily directed at components whose production or procured volume is large enough, during some predefined sampling period, to give statistically meaningful information. 7.0 METHODS 7.1 There are currently three standards ava

20、ilable to the electronics industry for determining the proportion nonconforming and for providing standardized definitions of PPM nonconforming. Each is applicable in a particular situation and care should be used when selecting any method. It is particularly important that the assumptions associate

21、d with each method be examined to ensure that the results obtained will be meaningful to the user and truly representative of the process being evaluated. 7.2 The standards described in this document are applicable in three different situations: 7.2.1 Acceptance Inspection Sampling Using Attributes

22、Data This method is fully described in EIA 554-1. 7.2.2 Audit Inspection Sampling Using Attributes Data This method is fully described in EIA 554-2. 7.2.3 Inspection Sampling Using Variables Data This method is fully described in EIA 591. 7.3 The acceptance inspection sampling standard (EIA 554-1) i

23、s designed for use with data from a traditional lot-by-lot acceptance inspection. The data gathered from such an activity are used to calculate Average Outgoing Quality (AOQ) expressed as PPM. Since this type of inspection is often done prior to the shipment of product it may not be necessary to add

24、 a separate inspection step. If sample sizes are sufficient, this method provides 90% statistical confidence that the reported AOQ PPM values are within 30% of the true population AOQ value. If sample sizes are insufficient to do this, formulas to calculate a one-sided upper 90% confidence bound are

25、 included. If specified conditions are met, a procedure for exclusion of abnormal data is available in this method. EIA - 554A Page 4 7.4 The audit inspection sampling standard (EIA 554-2) is designed for use when audit inspection is performed. Audit inspection is not used to accept or reject produc

26、t but only to gather data to assess quality levels. This method has a built-in statistical confidence so that no additional calculation is required. This method may be used in situations where acceptance inspection is not performed or at any point in a process where data can be obtained to estimate

27、quality levels. If specified conditions are met, a procedure for exclusion of abnormal data is available in this method. 7.5 The variables inspection sampling standard (EIA-591) is designed for use when traditional attributes sampling methods (7.3 and 7.4) are not desirable. Attributes inspection ty

28、pically requires large sample sizes. The use of variables sampling can provide statistically meaningful estimates with significantly reduced sample sizes. The procedure described in this standard is a useful approach to estimating PPM nonconforming using variables data if, and only if, the data are

29、consistent with the assumption of an underlying population distribution that is normal (Gaussian). If this assumption is met, this method can provide a cost effective method for estimating PPM nonconforming with relatively small sample sizes. EIA - 554A Page 5 8.0 SUMMARY The following table provide

30、s a comparison of the methods presented in the three standards described in this document. EIA 554-1 EIA 554-2 EIA 591 What is it? Acceptance sampling Audit sampling Inspection sampling using attributes data using attributes data using variables data Approach Assesses AOQ PPM Assesses PPM Assesses P

31、PM nonconforming using nonconforming using nonconforming using attributes data from attributes data from variables data acceptance inspection audit inspection Primary Provides PPM Provides PPM Provides PPM Advantage nonconforming nonconforming nonconforming estimate from existing estimate with built

32、in estimate from acceptance sampling statistical confidence variables data with operations with level smaller sample sizes statistical confidence than are required for the level and minimum same statistical confidence sample size calculation using attributes data Primary Requires relatively Require

33、s relatively Limited to quality Disadvantage large sample sizes large sample sizes characteristics with normal distributions Recommended When reporting PPM When reporting PPM When reporting PPM for use nonconforming levels nonconforming levels nonconforming levels using attributes data using attribu

34、tes data from using variables data from outgoing audit inspection acceptance inspection TechAmerica Document Improvement Proposal If, in the review or use of this document, a potential change is made evident for safety, health, or technical reasons please fill in the appropriate information below an

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