๐Ÿ”ฅ๐Ÿ”ฅ Donโ€™t Miss Out on Our End of Autumn Sale. If you have any questions, feel free to click the bottom right corner to contact our customer service..

Concat us[email protected]
Shopping Cart

No products in the cart.

๐Ÿ”
BSI PD IEC TR 61191-7:2020

BSI PD IEC TR 61191-7:2020

$215.11

Printed board assemblies – Technical cleanliness of components and printed board assemblies

Published By Publication Date Number of Pages
BSI 2020 118
PDF Format Searchable Printable Preview Now
Guaranteed Safe Checkout
Category:

If you have any questions, feel free to reach out to our online customer service team by clicking on the bottom right corner. Weโ€™re here to assist you 24/7.
Email:[email protected]

This part of IEC 61191 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.

PDF Catalog

PDF Pages PDF Title
2 undefined
4 CONTENTS
10 FOREWORD
12 INTRODUCTION
13 1 Scope
2 Normative references
3 Terms and definitions
4 Technical cleanliness
4.1 What is technical cleanliness?
14 4.2 History โ€“ standardisation of technical cleanliness
4.3 Technical cleanliness in the electronics industry
4.4 Potential particle-related malfunctions
15 5 Technical cleanliness as a challenge for the supply chain
5.1 General
16 5.2 Contamination
5.2.1 Definition of particles
5.2.2 Definition of fibres
17 5.3 Test procedure to determine technical cleanliness
5.3.1 Fundamentals
18 5.3.2 Clarification form
Figures
Figure 1 โ€“ Test method as per VDA 19 Part 1
20 5.3.3 System technology
Figure 2 โ€“ Examples of extraction systems
21 5.3.4 Process parameters for pressure rinsing extraction
5.3.5 Pressure rinsing process
22 5.3.6 Preparing membrane filters for measurement analysis
Figure 3 โ€“ Component holder during manual pressure rinsing
23 Figure 4 โ€“ Examples of different options for drying membrane filters
Figure 5 โ€“ Slide frame with membrane filter
24 5.4 Measurement analysis
5.5 Evaluating the results of cleanliness analyses
5.5.1 Overview
25 5.5.2 Particle count relative to component surface
26 5.5.3 Procedure for violation of action control limits
Figure 6 โ€“ Example procedure if specifications are exceeded
Tables
Table 1 โ€“ Influence of the blank value on the measurement results for different material surfaces (examples for a blank value fraction of 2,2 % and above)
27 5.6 Extended risk assessment
5.6.1 General
5.6.2 Example
28 Figure 7 โ€“ Particle size distribution and corresponding process capability
29 5.7 Component cleanliness โ€“ Data management and visualization
5.7.1 Component cleanliness analysis โ€“ flow diagram
Figure 8 โ€“ Flow diagram for component cleanliness analysis
Figure 9 โ€“ Scope of analytical report
30 5.7.2 Explanation of SCI (Surface Cleanliness Index)
Figure 10 โ€“ Derivation of Illig value
31 Figure 11 โ€“ Derivation of SCI
32 Figure 12 โ€“ Evaluation of 7-pin HV strip connector
Figure 13 โ€“ Graph showing cleaning effect based on SCIs
33 5.7.3 Creating a database
Figure 14 โ€“ Comparison of the three largest particles
34 Figure 15 โ€“ Structural levels of a database
Figure 16 โ€“ Option A โ€“ Evaluation of the largest particles by length and width
35 Figure 17 โ€“ Option B โ€“ Extension to include the degree of contamination โ€“ SCI
Figure 18 โ€“ Option C โ€“ Extension to include a separate data sheet “direct comparison of test series”
36 5.7.4 Summary
Figure 19 โ€“ Option D โ€“ Extension of the database “to include’comparison with customer standards'”
37 6 State of the art โ€“ Technical cleanliness in the electronics industry
6.1 Process flow (per cluster)
6.1.1 General
6.1.2 Electronics manufacturing cluster
Table 2 โ€“ Electronics manufacturing cluster process flow
38 6.1.3 Passive components cluster (e.g. for inductors and aluminium electrolytic capacitors)
Table 3 โ€“ Process flow for inductors
39 6.1.4 Electromechanical components cluster
Table 4 โ€“ Aluminium electrolytic capacitors
40 Table 5 โ€“ Stamped contact production/plastic production (housing) process flow
Table 6 โ€“ Housing assembly process flow
41 6.1.5 PCB cluster
6.2 Technical cleanliness in the electronics industry โ€“ current situation
6.2.1 General
Table 7 โ€“ PCB cluster process flow
42 6.2.2 Electronics manufacturing
Table 8 โ€“ Empirical data from electronics manufacturing cluster
43 6.2.3 Electronic components
Table 9 โ€“ Empirical data from inductors
Table 10 โ€“ Empirical data from aluminium electrolytic capacitors
44 Table 11 โ€“ Empirical data from tantalum capacitors
Table 12 โ€“ Empirical data from chip components
45 Table 13 โ€“ Empirical data from shunts
Table 14 โ€“ Empirical data from quartz
46 6.2.4 Electromechanical components
Table 15 โ€“ Empirical data from semiconductors
Table 16 โ€“ Empirical data from metallic components โ€“stamping from pre-treated strip stock
47 Table 17 โ€“ Empirical data from metallic components โ€“ stamping of contact from untreated strip stock and subsequent electroplating process
Table 18 โ€“ Empirical data from metallic components โ€“ turning of pins andsubsequent electroplating process
48 Table 19 โ€“ Empirical data from pure plastic parts
Table 20 โ€“ Empirical data from joined strip connectors
49 Table 21 โ€“ Empirical data from high-voltage connectors (typically shielded)
Table 22 โ€“ Empirical data from the assembly process of non-metallic components
50 6.2.5 Metal housings
Table 23 โ€“ Empirical data from die-cast aluminium housing
51 6.2.6 Packaging
6.2.7 Printed circuit boards (PCBs)
Figure 20 โ€“ Flexible circuit board
Table 24 โ€“ Empirical data from deep-drawn trays (new)
52 Figure 21 โ€“ Rigid circuit board
Table 25 โ€“ Empirical data from flexible PCBs without cleaning step
53 Table 26 โ€“ Empirical data from bare, flexible PCBs with cleaning step
Table 27 โ€“ Empirical data from bare, rigid PCBs
54 6.3 Determining potential particle sources in production areas
6.3.1 General
6.3.2 Particle generation
6.3.3 Electronics manufacturing cluster
55 6.3.4 Passive components cluster
56 Figure 22 โ€“ Burr formation on copper wire (D = 2,25 mm) after use of wire-cutter
Figure 23 โ€“ Particles generated by wire cutting D = 1,8 mm (tinned copper)
57 Figure 24 โ€“ Particles generated by wire cutting D = 1,8 mm (tinned copper)
Figure 25 โ€“ Particle (tin) adhering to a tinned copper wire D = 2,25 mm
58 Figure 26 โ€“ Hair-like particle (tin whiskers) chipped off a tinned wire (655 ยตm long)
Figure 27 โ€“ Milled enamel wires
59 Figure 28 โ€“ Molten solder balls fused to plastic housings
60 Figure 29 โ€“ Ferrite particle, identified as metallic (419 ยตm)
Figure 30 โ€“ Ferrite particle, identified as non-metallic (558 ยตm)
61 6.3.5 Electromechanical components cluster
Figure 31 โ€“ Non-metallic particle, probably burr or plastic residue (217 ยตm)
Figure 32 โ€“ Non-metallic particle, probably pink polystyrene packaging material
62 Figure 33 โ€“ Shielding plate
63 Figure 34 โ€“ Stamped contacts
Figure 35 โ€“ Connector pin
64 Figure 36 โ€“ Connector housing
Figure 37 โ€“ 58-pin connector housing
65 6.3.6 PCB cluster
Figure 38 โ€“ 12-pin connector with bridged contacts
66 Figure 39 โ€“ Plastic particles + fibres
Figure 40 โ€“ Plastic particles
Figure 41 โ€“ Metallic particle
67 Figure 42 โ€“ Milling crosses V-scoring line
68 Figure 43 โ€“ V-scoring line on milling edge
Figure 44 โ€“ Chip formation in milled hole
69 Figure 45 โ€“ Edge plating
Figure 46 โ€“ Connections for electroplated gold areas
70 Figure 47 โ€“ Deep milling
Figure 48 โ€“ Chip formation caused by stamping
71 Figure 49 โ€“ Flexible circuit board with undercut
Figure 50 โ€“ Punching burr in hole
72 Figure 51 โ€“ Punching burr
Figure 52 โ€“ Damaged metallic stiffener
73 Figure 53 โ€“ Stamping residue along stamped edge
Figure 54 โ€“ Stamping residue loosened by pickling bath
74 6.4 Cleanliness-controlled design and process selection
6.4.1 Aspects of cleanliness-controlled design/production with regard to metallic particles
Figure 55 โ€“ Plastic element with burr
Figure 56 โ€“ Particles on externally supplied plastic elements
76 6.4.2 Environmental cleanliness and internal production processes
77 Figure 57 โ€“ Process chain analysis as per VDA 19 Part 2
78 6.5 Environmental cleanliness analysis and visualisation
6.5.1 General
6.5.2 Procedure for environmental analysis
Figure 58 โ€“ Cleanroom production
79 Figure 59 โ€“ Example particle trap
Figure 60 โ€“ Position of particle trap
80 Figure 61 โ€“ Database โ€“ Visualisation
Figure 62 โ€“ Illustration of the Illig value with max. three particles
81 Figure 63 โ€“ Airborne dispersion diagram
Figure 64 โ€“ Analysis results in the cleanroom
82 6.5.3 Conclusions:
Figure 65 โ€“ Analysis results in the area not governed by VDA 19
Figure 66 โ€“ Weighting of factors influencing technical cleanliness
83 6.6 Cleaning tips
6.6.1 General
6.6.2 Washing
6.6.3 Brushing
84 6.6.4 Suction-cleaning
Figure 67 โ€“ Manual cleaning with brush and illuminated magnifier
Figure 68 โ€“ ESD brush
85 6.6.5 Blowing
6.6.6 Reducing carry-over and controlling cleanliness in workplace design
Figure 69 โ€“ Workstations designed for cleanliness control
86 6.6.7 Adhesive methods
6.7 Packaging and logistics requirements
7 Why do metallic particles in assemblies so rarely cause short circuits?
7.1 General
Figure 70 โ€“ Adhesive roller system for PCB contact cleaning
87 7.2 Probability of contact
7.2.1 Introduction and theory
Figure 71 โ€“ Diagram showing failure risks based on metallic particles on assemblies
88 Figure 72 โ€“ Sketch of electrical arrangement (particle forming “bridge” between two conductors)
89 Figure 73 โ€“ Diagram showing contact point of a particle on a conductor โ€“nickel-gold conductor and copper particle
90 7.2.2 Testing the probability of contact
Table 28 โ€“ List of materials used in the test
91 Figure 74 โ€“ SIR test circuit boards (interleaving comb pattern layout)
Figure 75 โ€“ Voltage source that measures current with an analogue picoamperemeter
92 7.2.3 Results
Figure 76 โ€“ Automated current measurement with software
93 Figure 77 โ€“ Comparison of CU particles in three conditions on SAC305 PCBs
Figure 78 โ€“ Overview of all metals in the voltage classes, rounded
94 7.3 Rinsing extraction versus actual mobility
7.4 Particle sinks
95 7.5 Effect of short circuits on ICs
7.6 Tool for estimating the risk of short circuit
7.6.1 Overview
96 7.6.2 Model hypotheses
Figure 79 โ€“ Functional structure of risk assessment tool
97 7.6.3 Calculation methods
7.6.4 Orientation factor
98 7.6.5 Critical area
Figure 80 โ€“ Geometric constraints at a contact pair
99 7.6.6 Number of particles per size class
Figure 81 โ€“ Clearance areas up to 400 ยตm (in white)
Figure 82 โ€“ Clearance areas up to 600 ยตm (in white)
Figure 83 โ€“ Clearance areas up to 1000 ยตm (in white)
100 7.6.7 Weighting factors
101 7.7 Example use of the risk assessment tool
7.7.1 Example use of the risk assessment tool for calculating failure rate
Figure 84 โ€“ Example calculation 1 โ€“ Calculating an absolute probability of failure
102 7.7.2 Example use of the risk assessment tool for design changes
Figure 85 โ€“ Example calculation 2 โ€“ Calculating probabilities of failurefor layout changes e.g. for a new generation component
103 7.7.3 Example use of the risk assessment tool for specification violations
Figure 86 โ€“ Example calculation 3 โ€“ Optimising the main variables
Figure 87 โ€“ Example calculation 3 โ€“ Calculating the changed probabilityof failure in the event of specification violation
104 8 Summary
9 Outlook
105 10 Related topics
10.1 Filmic contamination
10.1.1 General
10.1.2 Biological films
10.1.3 Chemical films
10.2 Whiskers
106 Figure 88 โ€“ Whiskers growth of > 8 mm over a period of 10 years
107 Figure 89 โ€“ Whiskers growth of > 2 mm over a period of 6 months
108 Annex A (informative)Determining the surface area of componentsand assembled circuit boards
Figure A.1 โ€“ Dimensions of cuboid components
109 Figure A.2 โ€“ Dimensions of cylindrical components
110 Table A.1 โ€“ Sample values of standard components to determinethe component surface area
111 Annex B (informative)Examples of cleanliness clarification forms
Figure B.1 โ€“ Ambient cleanliness clarification form
112 Figure B.2 โ€“ Ambient cleanliness clarification form
113 Figure B.3 โ€“ Component cleanliness clarification form
114 Figure B.4 โ€“ Component cleanliness clarification form
115 Figure B.5 โ€“ Component cleanliness clarification form
116 Bibliography

Related products

BSI PD IEC TR 61191-7:2020
$215.11