IEC TR 61191-7:2020

Printed board assemblies - Part 7: Technical cleanliness of components and printed board assemblies

IEC TR 61191-7:2020(E) serves as a Technical Report and provides information, how technical cleanliness can be assessed within the electronics assembly industry. Technical cleanliness concerns sources, analysis, reduction and control as well as associated risks of particulate matter, so-called foreign-object debris, on components and electronic assemblies in the electronics industry.

General Information

• Status: Published
• Publication Date: 10-Mar-2020
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 31.180 - Printed circuits and boards
• ICS: 31.190 - Electronic component assemblies
• Technical Committee: TC 91 - Electronics assembly technology
• Drafting Committee: WG 1 - TC 91/WG 1
• Current Stage: PPUB - Publication issued
• Start Date: 17-Feb-2020
• Completion Date: 11-Mar-2020

Standards Content (Sample)

IEC TR 61191-7 ®
Edition 1.0 2020-03
TECHNICAL
REPORT
colour
inside
Printed board assemblies –
Part 7: Technical cleanliness of components and printed board assemblies
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IEC TR 61191-7 ®
Edition 1.0 2020-03
TECHNICAL
REPORT
colour
inside
Printed board assemblies –
Part 7: Technical cleanliness of components and printed board assemblies

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.180; 31.190 ISBN 978-2-8322-7901-4

– 2 – IEC TR 61191-7:2020 © IEC 2020
CONTENTS
FOREWORD . 8
INTRODUCTION . 10
1 Scope . 11
2 Normative references . 11
3 Terms and definitions . 11
4 Technical cleanliness . 11
4.1 What is technical cleanliness? . 11
4.2 History – standardisation of technical cleanliness . 12
4.3 Technical cleanliness in the electronics industry . 12
4.4 Potential particle-related malfunctions . 12
5 Technical cleanliness as a challenge for the supply chain . 13
5.1 General . 13
5.2 Contamination . 14
5.2.1 Definition of particles . 14
5.2.2 Definition of fibres . 14
5.3 Test procedure to determine technical cleanliness . 15
5.3.1 Fundamentals . 15
5.3.2 Clarification form . 16
5.3.3 System technology . 18
5.3.4 Process parameters for pressure rinsing extraction . 19
5.3.5 Pressure rinsing process . 19
5.3.6 Preparing membrane filters for measurement analysis . 20
5.4 Measurement analysis . 22
5.5 Evaluating the results of cleanliness analyses. 22
5.5.1 Overview . 22
5.5.2 Particle count relative to component surface . 23
5.5.3 Procedure for violation of action control limits . 24
5.6 Extended risk assessment . 25
5.6.1 General . 25
5.6.2 Example . 25
5.7 Component cleanliness – Data management and visualization . 27
5.7.1 Component cleanliness analysis – flow diagram . 27
5.7.2 Explanation of SCI (Surface Cleanliness Index) . 28
5.7.3 Creating a database . 31
5.7.4 Summary . 34
6 State of the art – Technical cleanliness in the electronics industry . 35
6.1 Process flow (per cluster) . 35
6.1.1 General . 35
6.1.2 Electronics manufacturing cluster . 35
6.1.3 Passive components cluster (e.g. for inductors and aluminium
electrolytic capacitors) . 36
6.1.4 Electromechanical components cluster . 37
6.1.5 PCB cluster . 39
6.2 Technical cleanliness in the electronics industry – current situation . 39
6.2.1 General . 39
6.2.2 Electronics manufacturing . 40

6.2.3 Electronic components. 41
6.2.4 Electromechanical components. 44
6.2.5 Metal housings . 48
6.2.6 Packaging. 49
6.2.7 Printed circuit boards (PCBs) . 49
6.3 Determining potential particle sources in production areas . 52
6.3.1 General . 52
6.3.2 Particle generation . 52
6.3.3 Electronics manufacturing cluster . 52
6.3.4 Passive components cluster . 53
6.3.5 Electromechanical components cluster . 59
6.3.6 PCB cluster . 63
6.4 Cleanliness-controlled design and process selection . 72
6.4.1 Aspects of cleanliness-controlled design/production with regard to
metallic particles . 72
6.4.2 Environmental cleanliness and internal production processes . 74
6.5 Environmental cleanliness analysis and visualisation . 76
6.5.1 General . 76
6.5.2 Procedure for environmental analysis . 76
6.5.3 Conclusions: . 80
6.6 Cleaning tips . 81
6.6.1 General . 81
6.6.2 Washing . 81
6.6.3 Brushing . 81
6.6.4 Suction-cleaning . 82
6.6.5 Blowing. 83
6.6.6 Reducing carry-over and controlling cleanliness in workplace design . 83
6.6.7 Adhesive methods . 84
6.7 Packaging and logistics requirements . 84
7 Why do metallic particles in assemblies so rarely cause short circuits? . 84
7.1 General . 84
7.2 Probability of contact . 85
7.2.1 Introduction and theory . 85
7.2.2 Testing the probability of contact . 88
7.2.3 Results . 90
7.3 Rinsing extraction versus actual mobility . 92
7.4 Particle sinks . 92
7.5 Effect of short circuits on ICs . 93
7.6 Tool for estimating the risk of short circuit . 93
7.6.1 Overview . 93
7.6.2 Model hypotheses . 94
7.6.3 Calculation methods . 95
7.6.4 Orientation factor . 95
7.6.5 Critical area . 96
7.6.6 Number of particles per size class . 97
7.6.7 Weighting factors . 98
7.7 Example use of the risk assessment tool . 99
7.7.1 Example use of the risk assessment tool for calculating failure rate . 99
7.7.2 Example use of the risk assessment tool for design changes . 100

– 4 – IEC TR 61191-7:2020 © IEC 2020
7.7.3 Example use of the risk assessment tool for specification violations . 101
8 Summary . 102
9 Outlook . 102
10 Related topics .
...