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1、BRITISH STANDARD BS CECC 00800:1988 Harmonized system of quality assessment for electronic components Code of practice for the use of the ppm approach in association with the CECC system UDC 621.38:(083.75):001.4 (087.3) Licensed Copy: London South Bank University, London South Bank University, Fri
2、Dec 08 16:56:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS CECC 00800:1988 This British Standard, having been prepared under the direction of the Electronic Components Standards Committee, was published under the authority of the Board of BSI and comes into effect on 29 February 1988 BSI 09-1999
3、The following BSI references relate to the work on this standard: Committee reference ECL/- Draft announced in BSI News November 1987 ISBN 0 580 16443 8 Committees responsible for this British Standard The preparation of this British Standard was authorized by the Electronic Components Standards Com
4、mittee (ECL/-), upon which the following bodies were represented: Association of Control Manufacturers TACMA (BEAMA Ltd.) British Telecommunications plc. Department of Trade and Industry (Electronics Applications Divisions) Electronic Components Industry Federation Electronic Engineering Association
5、 Institution of Electronic and Radio Engineers Ministry of Defence National Supervising Inspectorate Society of British Aerospace Companies Limited Telecommunication Engineering and Manufacturing Association (TEMA) Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: Lond
6、on South Bank University, London South Bank University, Fri Dec 08 16:56:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS CECC 00800:1988 BSI 09-1999i Contents Page Committees responsibleInside front cover National forewordii Forewordiii Text of CECC 008001 Publications referred toInside back cover
7、Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 16:56:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS CECC 00800:1988 ii BSI 09-1999 National foreword This British Standard has been prepared under the direction of the Electronic Components Standards Committee.
8、It is identical with CENELEC Electronic Components Committee (CECC) 00800:1986 “Harmonized system of quality assessment for electronic components. Code of practice on the use of the ppm approach in association with the CECC system”. This standard is a harmonized specification within the CECC system.
9、 Details of the national implementation of CECC standards is given in BS 9000 “General requirements for a system for electronic components of assessed quality” Part 2 “Specification for national implementation of CECC basic rules and rules of procedure” . Terminology and conventions. The text of the
10、 CECC code of practice has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards. A British Standard does not purport to include all the necessary provisions of a contract. Us
11、ers of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-reference International StandardCorresponding British Standard CECC 00014:1986BS CECC 00014:1988 Harmonized system of quality as
12、sessment for electronic components. Basic specification: CECC assessed process average procedure (60 % confidence level) (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the CECC title page, pages ii to iv, pages 1 to 6, an inside back cover
13、and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 16:56:24 GMT+00:00 2006, Unco
14、ntrolled Copy, (c) BSI Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 16:56:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS CECC 00800:1988 ii BSI 09-1999 Contents Page Forewordiii Prefaceiii 1Introduction1 2The CECC Systems relationship with AQL, APA and ppm
15、methods1 3Basic principles of the ppm approach1 4The use of the ppm approach in association with the CECC System2 5Conclusion2 Annex A Terminology associated with the ppm approach3 Annex B The use of the ppm approach in association with the CECC System4 Annex C Defect analysis and rectification prog
16、ramme for operation of the ppm approach5 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 16:56:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS CECC 00800:1988 BSI 09-1999iii Foreword The CENELEC Electronic Components Committee (CECC) is composed of those member
17、 countries of the European Committee for Electrotechnical Standardization (CENELEC) who wish to take part in a harmonized System for electronic components of assessed quality. The object of the System is to facilitate international trade by the harmonization of the specifications and quality assessm
18、ent procedures for electronic components, and by the grant of an internationally recognized Mark, or Certificate, of Conformity. The components produced under the System are thereby accepted by all member countries without further testing. At the date of printing of this publication, the member coun
19、tries of the CECC are Austria, Belgium, Denmark, Finland, France, Germany, Ireland, Italy, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Preface This “Code of Practice on the use of the ppm approach in association with the CECC System” was prepared by CECC Wor
20、king Group “Assessment Techniques”. The text of this “Code of Practice” was circulated to the CECC for voting in the document indicated below and was ratified by the President of the CECC for printing: DocumentDate of VotingReport on the Voting CC(Secretariat) 1809December 1985CECC (Secretariat) 187
21、4 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 16:56:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 16:56:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS CECC 00800
22、:1988 BSI 09-19991 1 Introduction The ppm approach provides the climate, opportunity, and procedures for extending quality improvement beyond “conformance to specification” into the field of “fitness for use” with the prime objective of decreasing progressively the level of component rejection occur
23、ring right through the equipment manufacturing process. This level is then measured in units of parts per million (or ppm) as a proportion of the total quantity delivered and used in the specified application. A necessary starting point for any satisfactory application of the ppm approach is a good
24、and technically-sound specification. The CECC System offers a structure of mutually-compatible specifications which are written in accordance with clearly-defined rules and which are very suitable for use with the ppm approach. To employ the principle of the ppm approach between the manufacturer and
25、 the user of an electronic component in order to reach the agreed target, there is need for the establishment of close cooperation between the two parties. This requirement applies throughout the commercial, technical, manufacturing and quality areas of the companies concerned. NOTEAnnex A contains
26、definitions of the terminology used in this Code of Practice. 2 The CECC systems relationship with AQL, APA and PPM methods The CECC System is based on the assessment of component quality in accordance with comprehensive, consistent and precise component detail specifications. The initial assessment
27、 is carried out by means of qualification or capability approval testing, and is followed by testing on a lot-by-lot and periodic basis. In order to sustain confidence in component quality without increasing testing costs to unreasonable levels, statistical sampling methods are applied, usually in a
28、ssociation with defined Acceptable Quality Levels (AQLs). In practice, the actual level of quality is usually far better than the AQL. In order to reflect the actual level of component quality, the CECC System has been augmented by a procedure for determining the Assessed Process Average (APA). This
29、 procedure, published as CECC 00014, applies primarily to large scale production and enables the manufacturer to accumulate and analyse the results of inspection for non-operatives over a number of lots and, on the basis of the information obtained, to determine an APA figure for information to his
30、customers. The procedures associated with both AQL and APA methods are essentially component-based and provide information concerning the components conformance to the relevant detail specification. These procedures do not relate directly to possible end uses of the component, as the equipment manuf
31、acturer, the final use and the operating environment of a component are frequently unknown to the component manufacturer. The ppm approach, in contrast, is intended to optimise the performance of a specific component in a given environment. It has the purpose of minimising rejects and ensuring the c
32、omponents conformance to usability requirements in the particular application for which it is employed by the equipment maker concerned. To achieve this aim, detailed verification and analysis of rejected components are required and it is essential that the component manufacturer and the component u
33、ser maintain close liaison to permit an efficient and rapid response to the results of this analysis. Because of the different basis of the ppm approach, there is no mathematical relationship with values of AQL or APA. 3 Basic principles of the PPM approach A decision to adopt the ppm approach may b
34、e reached by the manufacturer and the user of a component as an extension of quality disciplines beyond the present scope of the CECC System, but not in conflict with its principles. The principal characteristics of the ppm approach are: 3.1 Basic assumption: it is in the interest of both the compon
35、ent manufacturer and the component user to seek manufacture of the component and of the equipment approaching the level of “zero defects”. 3.2 The objects are: 3.2.1 to ensure that the manufacturer is producing the most suitable component for the user and that the user is employing that component ap
36、propriately 3.2.2 to improve not only the quality of the component, but also the context in which it is used 3.2.3 to provide a means of measuring the results achieved and comparing them with the target of “zero defects”. 3.3 The requirements are: 3.3.1 to ensure that both the manufacturer and the u
37、ser of the component recognize commercial benefits which are derived from the use of the ppm approach Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 16:56:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS CECC 00800:1988 2 BSI 09-1999 3.3.2 to ensure close coope
38、ration between the individual manufacturer and the individual user of the component, to develop mutual confidence 3.3.3 to recognize that the ppm approach is always specific to individual component types and to their precise application 3.3.4 to establish clear objectives with regard to defect level
39、s and timescales 3.3.5 to identify any component defect and, by cooperation, establish the mode of defect. 4 The use of the PPM approach in association with the CECC System (see also Annex B) 4.1 During the equipment design stage, great care is required to ensure that the component is used within it
40、s specified conditions of use and in the optimum manner, taking account of the way in which the component will be assembled into the equipment. 4.2 It is necessary to match technical and economic requirements as closely as possible. 4.3 The requirements in 4.1 and 4.2 should be documented in the for
41、m of a CECC detail specification, containing limiting values, characteristics and tests with the associated acceptance limits. 4.4 The component in question should be submitted for qualification or capability approval in accordance with this detail specification, and the approval should be maintaine
42、d for the duration of the components use in the specified context. 4.5 A defect analysis programme shall be instituted for the purpose of identifying and rectifying the causes of defects. This defect analysis and rectification programme is illustrated in Annex C. 4.6 As a result of the actions taken
43、 under 4.3, 4.4 and 4.5, remedial actions may be required, individually or in combination: 4.6.1 amendment of the component detail specification, in order to correct errors which have been detected, to define some parameters more closely, to include characteristics which may have been omitted, or to
44、 vary the specified limiting values and guidance for the use of the component 4.6.2 modification of materials or of manufacturing or handling techniques 4.6.3 as a result of actions taken under 4.6.1 and 4.6.2, retesting or requalification of the component, as necessary 4.6.4 modification of the equ
45、ipments design, assembly or handling, to remove any unnecessary and undesirable stresses 4.6.5 in extreme cases, modification of field use conditions, where it is impossible to reduce the defect rate by other methods. 4.7 A ppm approach project may be given a target value for defect rate, the achiev
46、ement of which signifies the successful completion of the project. 4.8 Where it becomes obvious that the target has not been reached but further progress cannot be achieved without disproportionate effort and expenditure, the manufacturer and the user of the component may declare the project complet
47、e. However, it should be kept under review and cooperation should continue. 4.9 The processes which are described above may result in a large number of sequential and/or parallel activities. 4.10 While it is recognized that the ppm approach is concerned with components in equipment design and manufa
48、cture, field failure data provide additional sources of valuable information affecting component use and selection. 4.11 A flowchart illustrating the use of the ppm approach is given in Annex B. 5 Conclusion As indicated in 4.6, a number of courses of action are available for the reduction of excess
49、ive defect rates. The need for defect analysis and subsequent remedial action can be indeed, should be reduced as much as possible before equipment assembly begins. The methods for achieving this are indicated in 4.1 to 4.4. Particular emphasis should be given to the potential benefits of the CECC System, which offers independent supervision of component conformance, standard quality assessment methods and the disciplines of a firmly- regulated structure of specifications. The CECC System provides a sound basis for the commencement of projects to minimise defect rat
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