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1、BRITISH STANDARD BS EN 61188-1-1:1997 IEC 61188-1-1: 1997 Printed boards and assemblies Design and use Part 1: Generic requirements Section 1: Flatness considerations for electronic assemblies The European Standard EN 61188-1-1:1997 has the status of a British Standard ICS 31.180 Licensed Copy: shef
2、fieldun sheffieldun, na, Fri Nov 10 16:41:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 61188-1-1:1997 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 Dece
3、mber 1997 BSI 03-1999 ISBN 0 580 28734 3 National foreword This British Standard is the English language version of EN 61188-1-1:1997. It is identical with IEC 61188-1-1:1997. The UK participation in its preparation was entrusted to Technical Committee EPL/501, Electronic assembly technology, which
4、has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them i
5、n the UK. A list of organizations represented on this committee can be obtained on request to its secretary. From 1 January 1997, all IEC publications have the number 60000 added to the old number. For instance, IEC 27-1 has been renumbered as IEC 60027-1. For a period of time during the change over
6、 from one numbering system to the other, publications may contain identifiers from both systems. Cross-references Attention is drawn to the fact that CEN and CENELEC Standards normally include an annex which lists normative references to international publications with their corresponding European p
7、ublications. The British Standards which implement these international or European publications may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British
8、Standard does not purport to include all the necessary provisions of 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. Summary of pages This document comprises a front co
9、ver, an inside front cover, pages i and ii, the EN title page, pages 2 to 8 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. Amendments issued since publication Amd
10、. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 10 16:41:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN 61188-1-1:1997 BSI 03-1999i Contents Page National foreword Inside front cover Foreword 2 Text of EN 61188-1-1 3 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 10 1
11、6:41:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 10 16:41:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 61188-1-1 October 1997 ICS 31.180 Descriptors: Printed circuits, printed boards
12、and assemblies, design, use, basic requirements, deviations from flatness, placement of SMD English version Printed boards and printed board assemblies Design and use Part 1-1: Generic requirements Flatness considerations for electronic assemblies (IEC 61188-1-1:1997) Cartes imprimes et cartes impri
13、mes quipes Conception et utilisation Partie 1-1: Prescriptions gnriques Considrations concernant la planit densembles lectroniques (CEI 61188-1-1:1997) Leiterplatten und Flachbaugruppen Konstruktion und Anwendung Teil 1-1: Allgemeine Anforderungen Gesichtspunkte zur Ebenheit von elektronischen Baugr
14、uppen (IEC 61188-1-1:1997) This European Standard was approved by CENELEC on 1997-10-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date
15、 lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under t
16、he responsibility of a CENELEC member into its own language and notified to the Central Secretariat 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, Luxe
17、mbourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Bruss
18、els 1997 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 61188-1-1:1997 E Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 10 16:41:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 61188-1-1:1997 BSI 03-1999 2 Foreword The text o
19、f document 52/721/FDIS, future edition 1 of IEC 61188-1-1, prepared by IEC TC 52, Printed circuits, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 61188-1-1 on 1997-10-01. The following dates were fixed: Annexes designated “normative” are part of the body of the sta
20、ndard. In this standard, Annex ZA is normative. Annex ZA has been added by CENELEC. Endorsement notice The text of the International Standard IEC 61188-1-1:1997 was approved by CENELEC as a European Standard without any modification. Contents Page Foreword 2 Introduction3 1Scope3 2Normative referenc
21、e3 3Basic requirements3 3.1Design3 3.2Rigid board manufacture3 3.3Assembly3 3.4Use3 4Deviations from flatness Rigid copper-clad base material3 4.1Causes3 4.2Prevention and correction4 4.3Test methods and requirements4 5Deviations from flatness Unassembled rigid printed boards4 5.1Causes4 5.2Preventi
22、on5 5.3Rectification5 5.4Requirements for flatness6 5.5Measurement methods6 6Deviations from flatness Rigid printed board assemblies6 6.1Causes6 6.2Prevention6 6.3Correction6 7Problems associated with placement of surface-mounted components7 7.1Placement of components (assembly)7 7.2Requirements for
23、 “pick-and-place” machines7 8Deviations from flatness in service7 9Prevention summary7 10Corrective action summary7 Annex ZA (normative) Normative references to international publications with their corresponding European publications8 Table 1 Manufacturing stages and preventive measures7 Table 2 Ma
24、nufacturing stages and corrective actions7 latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement(dop) 1998-07-01 latest date by which the national standards conflicting with the EN have to be withdrawn(dow) 1998-07-01 L
25、icensed Copy: sheffieldun sheffieldun, na, Fri Nov 10 16:41:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 61188-1-1:1997 BSI 03-19993 Introduction Rigid printed board technology demands a high degree of flatness in substrates and assemblies and distortion may result from a number of causes. All i
26、ndividuals involved at any stage of design, manufacture and use shall be aware of and understand the potential problems. It is essential that they pay specific attention to those factors under their control. The following table shows the references to the three test methods given in IEC 61189-2. Bow
27、 and twist test method checklist for materials 1 Scope This part of IEC 61188 describes those factors which control the flatness of rigid printed boards and their assemblies. The object of this standard is to inform the designer, manufacturer, assembler and user of rigid printed boards and their ass
28、emblies about those factors affecting their flatness. This standard incorporates advice regarding: design (clause 3); base material (clause 4); unassembled printed boards (clause 5); printed board assemblies (clause 6). 2 Normative reference The following normative documents contain provisions which
29、, through reference in this text, constitute provisions of this part of IEC 61188. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this part of IEC 61188 are encouraged to investigate the possibility o
30、f applying the most recent editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. IEC 61189-2:1977, Test methods for electrical materials, interconnection structures and assemblies Part 2: Test methods for materials
31、for interconnection structures. 3 Basic requirements 3.1 Design The designer of the rigid board/assembly shall aim to achieve a mechanically balanced construction. For the printed board, balanced construction pertains to the even distribution of the amount of resin, reinforcement and metallic foil a
32、bout the centre of the board in any axis. In addition, if metal is bonded to the substrate (e.g. as a heat sink) the contribution to flatness provided by the metal must be understood. Printed board assemblies usually have components on only one side. However, with the advent of surface mounting, man
33、y designs have both sides of the board populated with components. Proper location of components by size, weight and the number of leads to be attached to the board will improve the flatness characteristics of the assembly. 3.2 Rigid board manufacture The rigid board manufacturer shall consider how t
34、o use and process the material to minimize distortion. 3.3 Assembly The rigid board assembler shall try to ensure that no distortion is introduced, particularly during soldering and handling operations. 3.4 Use The user shall, by good storage and equipment practice, minimize the likelihood of distor
35、tion occurring after assembly. 4 Deviations from flatness Rigid copper-clad base material 4.1 Causes The following can contribute, either singly or in combination, to distortion of copper-clad material. 4.1.1 Reinforcement Glass fabrics may be stressed during weaving and treatment. Distortion of the
36、 laminated product introduced by individual sheets of stressed glass fabric will be small. 4.1.2 Copper foil The effect of the copper foil on distortion is usually small. 4.1.3 B-stage material (prepreg) Impregnation of the reinforcement with resin, which is subsequently partially cured, produces “B
37、-stage” base material (prepreg). Non-uniform impregnation can produce stresses which result in distortion in the laminated product. These stresses may be attributed to: uneven tension applied to the reinforcement as it passes through the treater (resin impregnator); ParameterConditionIEC 61189-2 Tes
38、t No. Bow Bow Twist Twist As received After processing As received After processing 2M01 2M02 2M01 2M04 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 10 16:41:34 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 61188-1-1:1997 4 BSI 03-1999 uneven or non-uniform thickness of resin across the reinf
39、orcement sheet width; improper curing (polymerization) of the resin, that is, under or over cure at the B-stage. 4.1.4 Lamination Non-uniform laminating pressure and temperature builds in stresses. Unbalanced construction, i.e. plies which are out of alignment in the X and Y directions will cause st
40、resses to be present. Foil on one side only of a laminate can make any distortion worse. The thicker the foil, the greater will be the distortion. In addition, when one side of a laminate is clad with thicker foil than the other, distortion can result. 4.1.5 Cutting and handling Cutting methods can
41、induce stress. Storage of the finished material other than in the horizontal plane can cause distortion. 4.2 Prevention and correction To minimize distortion the factors discussed in 4.1 shall be controlled. Attention will be paid to the design engineering and specification. Process control has to b
42、e performed. Once lamination has been completed corrective action is not possible if internal stresses have been built into the base material. Glass transition temperature (Tg): The Tg is the temperature at which a thermosetting plastic changes from a glass-like (rigid) state to a deformable (flexib
43、le) state. This change is completely reversible; the material will behave like a glass below the Tg and like deformable material above it. Therefore, deformations introduced in the deformable state will be locked in when the material reverts to the glass-like state. The Tg of epoxide woven glass fab
44、ric materials in common use is normally in the range of 120 C to 135 C but can be as low as 105 C. Other resins can have a significantly different Tg. If the laminated material is not flat at room temperature, the presence of internal stress is obvious. However, even if the material is flat at room
45、temperature, internal stresses can still be present. When the material is heated above the Tg of the resin, the resin no longer restrains the residual stresses and the material relaxes and appears flat. The distortion may, or may not, return if the base material is cooled down in an unrestrained con
46、dition. The distortion may be “corrected” by holding the base material flat while cooling to below the resin Tg but may reappear on reheating. 4.3 Test methods and requirements Test methods and values for a range of commonly used base materials are given in IEC 61189-2. Where there is no existing sp
47、ecification for the material being used in the IEC or equivalent national standards, it is recommended that agreement be reached between customer and supplier on limit values to be obtained using the accepted international standard test method. 5 Deviations from flatness Unassembled rigid printed bo
48、ards 5.1 Causes The following can contribute, either singly or in combination, to distortion of unassembled rigid printed boards. 5.1.1 Printed board design 5.1.1.1 Rigid printed board profile The shape of the profile can influence the amount of distortion. 5.1.1.2 Internal cutouts Large cutouts wit
49、h square corners or long slots centrally positioned may contribute to distortion. Designs incorporating rigid printed board profiles blanked and returned to panel may aggravate distortion. 5.1.1.3 Density and layout of conductive patterns The distortion of single-sided rigid printed boards is most influenced by foil thickness. The greater the area and thickness of copper in the design, the greater will be the distortion. Twist is prevalent in designs containing uneven copper distribution; for example, a design