BS CECC 00016-1991 Harmonized system of quality assessment for electronic components - Basic specification basic requirements for the use of statistical process control (SPC) in th.pdf

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1、BRITISH STANDARD BSCECC 00016:1991 Harmonized system of quality assessment for electronic components Basic specification: Basic requirements for the use of statistical process control (SPC) in the CECC SystemBSCECC 00016:1991 This British Standard, having been prepared under the directionof the Elec

2、tronic Components Standards PolicyCommittee, was publishedunder the authority ofthe Standards Board and comesinto effect on 20December1991 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference ECL Draft for comment 89/25010 DC ISBN 0 580 20357 3 Committees

3、 responsible for this British Standard This British Standard was entrusted by the Electronic Components Standards Policy Committee (ECL/-), upon which the following bodies were represented: BEAMA Ltd. British Standards Society British Telecommunications plc EEA (The Association of the Electronics, T

4、elecommunications and Business Equipment Industries) Electronic Components Industry Federation Ministry of Defence National Supervising Inspectorate Society of British Aerospace Companies Limited Amendments issued since publication Amd. No. Date CommentsBSCECC 00016:1991 BSI 08-1999 i Contents Page

5、Committees responsible Inside front cover National foreword ii Foreword iii Text of CECC 00016 1 Publication(s) referred to Inside back coverBSCECC 00016:1991 ii BSI 08-1999 National foreword This British Standard has been prepared under the direction of the Electronic Components Standards Policy Co

6、mmittee. It is identical with CECC00016:1990 “Harmonized system of quality assessment for electronic components: Basic specification: Basic requirements for the use of statistical process control (SPC) in the CECC System”, published by the European Committee for Electrotechnical Standardization (CEN

7、ELEC) Electronic Components Committee (CECC). This standard defines the requirements for the application of statistical process control (SPC) in the CECC System in order to improve the quality of processes, products and services by continually reducing process variation. The British Standard which i

8、mplements the CECC Rules of Procedure is BS9000 “General requirements for a system for electronic components of assessed quality” Part 2:1991 “Specification for the national implementation of the CECC System”. The Electronic Components Standards Policy Committee has reviewed the provisions of CECC00

9、011 to which reference is made in the text and has decided that they are acceptable for use in conjunction with this standard. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Complian

10、ce with a British Standard does not of itself confer immunity from legal obligations. Cross-references International standard Corresponding British Standard CECC 00114:RP 14 BS CECC 00114: Quality assessment procedures Part II Part 2:1991 Qualification approval of electronic components (Identical) C

11、ECC 00114:RP 14 BS CECC 00114: Quality assessment procedures Part III Part 3:1991 Capability approval of an electronic component manufacturing activity (Identical) EN 29001 BS 5750: Quality systems Part 1:1987 Specification for design/development, production, installation and servicing (Identical) S

12、ummary of pages This document comprises a front cover, an inside front cover, pages i and ii, theCECC title page, pages ii to iv, pages1to6, an inside back cover and abackcover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in th

13、e amendment table on theinside front cover.BS CECC 00016:1991 ii BSI 08-1999 Contents Page Foreword iii Preface iii 1 Introduction 1 2 Scope 1 3 Terminology 1 4 Relationship of SPC with CECC Qualification Approval and Capability Approval requirements 2 5 General requirements 2 6 Specific requirement

14、s 2 Annex A SPC typical flow chart 5 Annex B SPC loops 6BS CECC 00016:1991 BSI 08-1999 iii Foreword The CENELEC Electronic Components Committee (CECC) is composed of those member countries of the European Committee for Electrotechnical Standardization (CENELEC) who wish to take part in a harmonized

15、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 assessment procedures for electronic components, and by the grant of an internationally recognized Mark, or Certificate, of Confo

16、rmity. The components produced under the System are thereby acceptable in all member countries without further testing. At the date of printing of this specification, the member countries of the CECC are Austria, Belgium, Denmark, Finland, France, Germany, Ireland, Italy, the Netherlands, Norway, Po

17、rtugal, Spain, Sweden, Switzerland and the United Kingdom, and copies of it can be obtained from the addresses shown on the blue fly sheet. Preface This Basic Specification was prepared by the CECC Task Force on Statistical Process Control. The text of this specification was circulated to the CECC f

18、or voting in the document indicated below and was ratified by the President of the CECC for printing as a CECC Specification. Document Date of Voting Report on the Voting CECC(Secretariat)2480 February 1990 CECC(Secretariat)2628iv blankBS CECC 00016:1991 BSI 08-1999 1 1 Introduction CECC approved co

19、mponents are released under either Qualification Approval (see CECC00114:RP14 Part II), or Capability Approval (seeCECC00114:RP14 Part III). Statistical Process Control (SPC) is a tool which may be used within the CECC System to demonstrate the degree to which the relevant manufacturing processes ar

20、e under control. When the technique is properly applied, it can assist in improving the outgoing product quality, particularly where the number of non-conforming items may be expressed as a low number of parts per million (ppm). No conventional sampling plan, nor even 100% inspection, can accurately

21、 separate out these low level non-conforming items. The only viable approach to quality in this situation is to institute a preventive methodology in the manufacturing process to build quality into the product, adopting a “proactive” method which allows for the improvement of the process on a contin

22、uing basis. SPC is used at the operational level to reduce process variation. SPC is based upon the prevention of failures through the application of statistical tools. It does not eliminate the measurement of products or of product parameters, i.e. inspections, which may be carried out on a samplin

23、g basis or 100%. However, statistical analysis will provide insight into the process and opportunities for improvement. As the process improves, there is a reduced need for extensive testing after the product is completed, with a consequent lowering of the manufacturing cost. By the use of statistic

24、al techniques, process variation with time can be quantified. Corrective actions which are based on this information will lead to continuing improvement in processes and products. A prerequisite for effective implementation of an SPC system is management commitment. This commitment is demonstrated b

25、y involvement and participation in project selection, progress reviews and continuing improvement activities. 2 Scope This specification defines the requirements for the application of statistical process control (SPC) in the CECC System in order to improve the quality of processes, products and ser

26、vices by continually reducing process variation. 3 Terminology 3.1 common or random cause a source of natural variation that affects all individual values of the process output being studied 3.2 control loop a corrective system based on feedback procedure 3.3 control limits the maximum allowable var

27、iation of a process characteristic due to common causes alone. Variation beyond a control limit is evidence that special causes may be affecting the process. Control limits are calculated from process data 3.4 node a point in the process where form, fit or function is altered 3.5 process a combinati

28、on of people, machines, equipment, materials, procedures, methods and environment that produces a given product or service 3.6 special or assignable cause a source of variation that is intermittent or unpredictable, affecting only some individual values of the process output 3.7 target value the nom

29、inal value of a characteristic 3.8 variation (see Note) the difference between individual outputs of a process; the source of variation can be grouped into two major classes: common causes and special causes NOTE“Variability” is sometimes used as an alternative term. 3.9 statistical control the cond

30、ition describing the process from which all special causes have been removed and only common causes remain; this is demonstrated by the absence of points beyond the control limits and by the absence of non-random patterns or trends within the control limitsBS CECC 00016:1991 2 BSI 08-1999 3.10 stati

31、stical process control (SPC) the conversion of data to information using statistical techniques to document, correct, and improve process performance 3.11 failure mode and effect analysis (FMEA) a disciplined analysis of possible failure modes on the basis of seriousness, probability of occurence an

32、d likelihood of detection. FMEA may be applied to both the design and the manufacturing process 3.12 fault tree analysis (FTA) (under consideration) 3.13 process potential an assessment of process capability made from a relatively small amount of sample data gathered over a short period of time, nor

33、mally carried out in a period of pilot or pre-production 3.14 process capability the natural variation of the process due to common causes 3.15 process characteristic a distinguishing feature of a process or its results on which variables or attributes data can be collected 3.16 process potential in

34、dex (C p ) and process capability index (C pk ) measures of the relationship between the specification limits and the process capability 3.17 control chart a plot of a process characteristic (for instance displayed as mean, range, standard deviation, percentage of defects) in its natural order (i.e.

35、, time of manufacturing) 4 Relationship of SPC with CECC Qualification Approval and Capability Approval requirements The CECC System is based on the assessment of quality in accordance with comprehensive, consistent and precise specifications. The initial assessment is carried out by means of qualif

36、ication or capability approval testing, and is followed by testing on a lot-by-lot and periodic basis. SPC techniques and concepts may be used by the manufacturer as a means of achieving a consistent level of quality in association with the requirements of the CECC System. For capability approval SP

37、C information may be used in support of the demonstration of capability within the defined technology and for release of product. Such information may be expressed quantitatively, for instance as capability indices. For qualification approval it is necessary to define and demonstrate a satisfactory

38、correlation between process data and product characteristics before SPC information can be used as part of conformance inspection. 5 General requirements 5.1 The manufacturer shall define an SPC system involving critical or key process nodes. 5.2 The manufacturer shall comply with the following SPC

39、relevant requirements of EN29001 “Quality systems Model for quality assurance in design/development, production, installation and servicing”: CECC 00011: Calibration requirements for the CECC System. These requirements form the infrastructure for the preparation and implementation of SPC. 6 Specific

40、 requirements 6.1 Preparing for SPC 6.1.1 Quality plans (clause 4.4.2 of EN29001) The manufacturer shall prepare written quality plans for projects relating to new processes. These plans shall include the activities concerning the definition and testing of the process and its controls. Clause: Requi

41、rement: 4.1 Management responsibility 4.2 Quality system 4.4 Design control 4.5 Document control 4.6 Purchasing 4.8 Product identification and traceability 4.9 Process control 4.10 Inspection and testing 4.12 Inspection and test status 4.13 Control of nonconforming product 4.14 Corrective action 4.1

42、6 Quality records 4.17 Internal quality audits 4.18 Training 4.20 Statistical techniquesBS CECC 00016:1991 BSI 08-1999 3 6.1.2 Nodes and characteristics (clause4.9 of EN29001) The manufacturer shall determine appropriate characteristics to be measured for the critical or key nodes. Tools to be used

43、while establishing those characteristics may include Failure Mode and Effect Analysis (FMEA), fault tree analysis (FTA), cause and effect diagrams and process flow charts. 6.1.3 Target values and limits (clause4.9 of EN29001) The target values and the limits of the characteristics beyond which the p

44、rocess will produce unacceptable (semi-) finished products shall be established. These limits are called specification limits. 6.1.4 Steering means (clause4.9 of EN29001) The manufacturer shall define the steering means necessary to keep the process under control. 6.1.5 Work instructions (clause4.9

45、of EN29001) The manufacturer shall prepare documented work instructions including inspection methods, the definition of deficiencies and the statistical methods to be used by the process operators. 6.1.6 Design reviews (clauses4.4 and 4.9 of EN29001) The manufacturer shall organize design reviews at

46、 defined intervals during the development of the process. All aspects of the development shall be considered. 6.1.7 Process potential studies (clause4.9 of EN29001) The manufacturer shall carry out process potential studies; test runs shall be made to observe the process characteristics. The results

47、 shall be statistically analysed, special causes shall be eliminated and unwanted trends shall be corrected. 6.1.8 Process capability studies (clause4.9 of EN29001) The manufacturer shall establish the process capability while operating it under actual production conditions until all factors likely

48、to contribute to process variation are reflected in the process output. During the investigation special causes shall be identified and eliminated to leave the process in statistical control. Data resulting from special causes can only be eliminated if there is no possibility of recurrence. From the

49、 process data, control limits shall be calculated and are to be used by operators as a basis for judging whether a process is affected by special causes. 6.1.9 Training (clause4.18 of EN29001) The manufacturer shall define, implement and maintain an SPC training programme for all personnel (including management) involved with SPC, reflecting the extent of their contribution. Special attention shall be paid to statistical aspects. 6.1.10 Management corrective action (clause4.1.2 of EN29001) The manufacturer shall define the management involvement in the systematic improveme