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1、BRITISH STANDARD BS CECC 00803:1996 Harmonized system of quality assessment for electronic components Guidance document: Visual inspection of soldered surface mounted assemblies ICS 31.020 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:23:25 GMT+00:00 2006,
2、Uncontrolled Copy, (c) BSI BS CECC 00803:1996 This British Standard, having been prepared under the direction of the Electrotechnical Sector Board, was published under the authority of the Standards Board and comes into effect on 15 July 1996 BSI 10-1999 The following BSI references relate to the wo
3、rk on this standard: Committee reference EPL/91 Draft for comment 94/204042 DC ISBN 0 580 25908 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee EPL/91, Surface mounting technology, upon which the following bodies were r
4、epresented: Association of Contract Electronics Manufacturers (ACEM) British Telecommunications plc Federation of the Electronics Industry Membrane Switch Manufacturers Association Ministry of Defence National Supervising Inspectorate (BSI Product Certification) Surface Mount and Related Technologie
5、s (Smart Group) Ltd. Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:23:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS CECC 00803:1996 BSI 10-1999i Contents Page Committees responsibleInside front cov
6、er National forewordii Foreword2 Text of CECC 008033 List of referencesInside back cover Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:23:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS CECC 00803:1996 ii BSI 10-1999 National foreword This British Standard
7、 has been prepared by Technical Committee EPL/91 and is identical with CECC 00803:1995 Guidance document: Visual inspection of soldered surface mounted assemblies, published by the European Committee for Electrotechnical Standardization (CENELEC) Electronic Components Committee (CECC). The British S
8、tandard which implements the CECC Rules of Procedure is BS 9000 General requirements for a system of electronic components of assessed quality Part 2:1996 Specification for the national implementation of the CECC system. A British Standard does not purport to include all the necessary provisions of
9、a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references Publication referred toCorresponding British Standard CECC 00802:1994BS CECC 00802:1994 Harmonized syst
10、em of quality assessment for electronic components. Guidance document: CECC Standard method for the specification of surface mounting components (SMDs) of assessed quality Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the CECC title page, pages 2 to 2
11、2, an inside back cover 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, Sat Dec 09 01:23
12、:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI GUIDANCE DOCUMENT DOCUMENT GUIDE LEITFADEN CECC 00803 August 1995 English version Guidance document: Visual inspection of soldered surface mounted assemblies (Nexiste pas en franais)Leitfaden: Sichtprfung von aufgelteten oberflchenmontierbaren Bauelemen
13、ten This CECC Specification was approved on 1995-06-17. This CECC Specification exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat
14、has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC Europe
15、an Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1995 Copyright reserved to CENELEC members Ref. No. CECC 00803:1995 E Licensed Copy: London Sout
16、h Bank University, London South Bank University, Sat Dec 09 01:23:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS CECC 00803:1996 2 BSI 10-1999 Foreword This guidance document was prepared by Working Group CLC/TC CECC/WG Surface Mounting Devices (SMT). The text of the draft based on document CECC (
17、Secretariat)3518 was submitted to the formal vote; together with the voting report, circulated as document CECC (Secretariat)3651, it was approved as CECC 00803 on 1995-06-17. Contents Page Foreword2 1Introduction3 2Scope4 3Related documents4 4Terminology5 4.1Definitions5 4.2Abbreviations, letter sy
18、mbols and signs6 5Pre-assembly in-process visual inspection6 5.1Method of inspection6 5.2Unpopulated printed boards and surface mounting components6 5.3Solder paste deposition7 5.4Non-conductive adhesive deposition7 5.5Component placement7 5.6Populated board prior to reflow soldering/adhesive curing
19、7 6Post soldering visual inspection of surface mounted assemblies7 6.1Method of inspection7 6.2General requirements for visual inspection of all SM soldered components and assemblies7 6.3General requirements for visual inspection of SM soldered assemblies8 6.4Visual inspection of SM component solder
20、 joints12 Figure 5.1 Adhesive Deposition7 Figure 6.3.12 (a) Fillet height10 Figure 6.3.12 (b) Fillet height referenced to Lead Thickness10 Figure 6.3.13 Solder wetting of plated through-holes without leads11 Figure 6.4.1 (a) Flat Ribbon, “L” and Gull Wing Lead joint description12 Page Figure 6.4.2 (
21、a) Round or Flattened (Coined) Lead joint description13 Figure 6.4.3 (a) “J” Lead joint description14 Figure 6.4.4 (a) Rectangular or Square End Components15 Figure 6.4.5 (a) Cylindrical End Cap terminations joint illustration16 Figure 6.4.6 (a) Bottom Only Terminations17 Figure 6.4.7 (a) Leadless C
22、hip Carriers with Castellated Terminations joint description18 Figure 6.4.8 (a) Butt Joint description19 Figure 6.4.9 (a) Inward L Lead description20 Figure 6.4.10 (a) Flat Lug Leads21 Table 6.4.1 (a) Dimensional Criteria Flat, Ribbon “L” and Gull Wing Leads12 Table 6.4.2 (a) Dimensional Criteria Ro
23、und or Flattened (Coined) Leads13 Table 6.4.3 (a) Dimensional Criteria “J” Leads14 Table 6.4.4 (a) Dimensional Criteria Rectangular or Square End Components15 Table 6.4.5 (a) Dimensional Criteria MELF Terminations16 Table 6.4.6 (a) Dimensional Criteria Bottom Only Terminations17 Table 6.4.7 (a) Dime
24、nsional Criteria Leadless Chip Carriers with Castellated Terminations18 Table 6.4.8 (a) Dimensional Criteria Butt Joints19 Table 6.4.9 (a) Dimensional Criteria Inward L Leads20 Table 6.4.10 (a) Dimensional Criteria Flat Lug Leads21 Licensed Copy: London South Bank University, London South Bank Unive
25、rsity, Sat Dec 09 01:23:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS CECC 00803:1996 BSI 10-19993 1 Introduction This specification applies to electronic assemblies containing surface mounted components and produced by using soldering techniques. It is targeted for human visual inspection. Altho
26、ugh the wetting and contour requirements for solder joints are equally applicable to automatic visual inspection, some differences in approach will be necessary in a future version for such methods. Surface mounted component terminations are designed for direct attachment to pre-determined conductiv
27、e footprint geometries which form part of the interconnection pattern on a supporting insulating substrate. The terminations may be either leads in disciplined format or leadless metallized areas on the surface of the component body. The leads provide a degree of mechanical flexibility between the c
28、omponent body and the substrate. In the case of leadless components, the metallized areas are joined directly to the footprint pads on the substrate and a comparatively rigid attachment structure results. Adhesives may be used to secure component bodies to the substrate prior to soldering. Even thou
29、gh many investigations have been dedicated to the interrelation of visual appearance of the joint and joint reliability, the results of such investigations do not allow a quick and simple assessment of the joint. Therefore the data given in this guideline reflects consensus practice rather than prov
30、en fitness for use. Post-mounting visual inspection of surface mounted components, joints and substrates should therefore be regarded primarily as a means of subjective decision on the likelihood of their suitability from mechanical, electrical and cleanliness standpoints. Secondly, the inspection i
31、s an important means of feedback in respect of substrate design, solder paste and adhesive quantity, placement accuracies, component termination and substrate footprint solderabilities, resistance to solder heat, cleaning-and all related process controls. This fact underlines the need for thorough t
32、raining of the operators and inspectors involved. New surface mount component types are continually emerging and the list of inspection points in this document should not be regarded as exhaustive. The limits given are considered applicable to board assemblies operating in a wide spectrum of industr
33、ial, automotive, computer, telecommunications and consumer products. Special considerations (not given in this document) apply to surface mount assemblies in high stress environments e.g. extended temperature range requirements, high power dissipation, shock, vibration. In specifying the criteria fo
34、r acceptance, a careful balance is required between the respective needs of process control, cosmetic factors and fitness for purpose. Unnecessarily restrictive dimensional tolerances can lead to excessive rework which, even if closely controlled, may deteriorate the long term reliability of solder
35、joints. Where approved quantitative methods are applied in determining joint strength, results from these should take precedence over cosmetic alignment, wetted area and joint contour aspects-though due allowance would be made for known reductions in strength with time and the effects of long term c
36、yclic stresses. The need for printed board designers and engineers to take note of this document before proceeding to surface mount printed board layout is strongly emphasized. If pad sizes or deposited solder paste quantities emerging from the design team (e.g. via CAD systems) are not correct, the
37、se specifications, may not be met. To avoid repetition, the guidelines in Section 6 are divided into general requirements and those specific to each termination type. Both are needed when compiling the complete visual inspection requirement for any given component. It is not practicable to specify e
38、very possible combination of shapes in three dimensions. Use of experienced judgement in visual inspection is inescapable in many cases, for example, in assessing nominal minimum and “average” solder fillet heights on leads and small components. The visual assessment criteria identified in this spec
39、ification can be used in a manufacturing environment employing statistical process control techniques. This can be achieved by viewing the requirements specified as product quality attributes and conducting the appropriate analysis. The application of the criteria is recommended to assist in process
40、 control in an environment where structured continuous improvement is sought for manufactured products. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 01:23:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS CECC 00803:1996 4 BSI 10-1999 2 Scope This guidance doc
41、ument applies to visual inspection criteria for electronic assemblies containing surface mounted components. The solder joint inspection requirements of this specification are applicable for component lead pitches down to 0.635 mm and for leadless components down to plan size 0603 (1.5 0.75 mm) or t
42、o 1.0 mm diameter. An extended version of this specification will apply both to smaller components and to thermode (hot bar) and laser soldering-the latter methods not being covered by the present text and drawings. The following areas, based upon tin lead alloy soldering are covered: 1) unpopulated
43、 printed boards; 2) solder paste and adhesive deposition; 3) shape of the soldered joint; 4) position of the component and soldered joint; 5) conditions of the components; 6) degree of wetting between component termination and the substrate. The inspection shall lead to decisions as to whether: the
44、soldered joints are acceptable; the soldered joint(s) should be rejected and eventually repaired and/or the assembly process should be improved the component is in an acceptable condition. 3 Related documents Typical steps in manufacturing CECC 00802:Issue 2 Guidance Document: CECC Standard Method f
45、or the specification of Surface Mounting Components (SMDs) of Assessed Quality prEN 160100:Issue 1 Sectional Specification: Capability approval of manufacturers of printed board assemblies of assessed quality currently CECC(Sec)3316 Licensed Copy: London South Bank University, London South Bank Univ
46、ersity, Sat Dec 09 01:23:25 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS CECC 00803:1996 BSI 10-19995 4 Terminology 4.1 Definitions 4.1.1 bridging the unwanted connection by solder of adjacent conducting surfaces 4.1.2 conductive adhesive an adhesive used for both electrical connection and mechanic
47、al attachment of component terminations to conductor footprints on a printed board 4.1.3 dewetting the withdrawal of molten solder from a metal surface which was initially wetted by the solder. It is characterized by dispersed and often irregularly shaped solder droplets, between which a thin coatin
48、g of solder may be left 4.1.4 disturbed joint a joint which has been mechanically disturbed at the moment of solidification 4.1.5 footprint a pattern of conductor areas on a printed board, designed for connection to a specific surface mounted component termination format 4.1.6 dissolution of metalli
49、zation (Leaching) the dissolution of a metallized surface layer into molten solder to the point where patchy local withdrawal of the original metallization occurs 4.1.7 non-conductive adhesive an adhesive used for mechanical attachment of surface mounted components to a printed board to keep them in place during a soldering operation 4.1.8 pinhole pinhole is an imperfection in the form of a small hole that penetrates entirely through a layer of material 4.1.9 pit a small, shallow