BSI PD IEC TR 61191-9:2023
$215.11
Printed board assemblies – Electrochemical reliability and ionic contamination on printed circuit board assemblies for use in automotive applications. Best practices
Published By | Publication Date | Number of Pages |
BSI | 2023 | 76 |
PDF Catalog
PDF Pages | PDF Title |
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2 | undefined |
4 | CONTENTS |
7 | FOREWORD |
9 | INTRODUCTION |
10 | 1 Scope 2 Normative references 3 Terms, definitions and abbreviated terms |
11 | 3.1 Terms and definitions related to management 3.2 Technical terms and definitions |
12 | 3.3 Abbreviated terms 4 Failure mode electrochemical migration 4.1 Background of electrochemical migration |
13 | Figures Figure 1 – Principal reaction mechanism of ECM Figure 2 – Uncertainty in local conditions determines ECM failures |
14 | 4.2 Complexity of electrochemical migration Figure 3 – Occurrence of ECM failures during humidity tests |
15 | 4.3 Conductive anodic filament (CAF) and anodic migration phenomena (AMP) Figure 4 – VENN diagram showing the factors influencing ECM |
16 | 4.4 Creep corrosion Figure 5 – Occurrence of CAF and AMP |
17 | 5 Electrochemical migration and relevance of ionic contamination 5.1 General aspects 5.2 Background of ionic contamination measurement Figure 6 – Creep corrosion caused by corrosive gases |
18 | Figure 7 – Ionic contamination measurement |
19 | 5.3 Restrictions and limitations of ionic contamination measurement for no-clean assemblies 5.3.1 Factors determining the result Figure 8 – Principal operation mode (fluid flow) of ROSE |
20 | 5.3.2 Influence by solvent on measurement of no-clean assemblies Figure 9 – Effect of solvent composition on the obtained ROSE results Figure 10 – Effect of solvent composition on the obtained ion chromatography result |
23 | 5.3.3 Influence of extraction time on measurement of no-clean assemblies Figure 11 – Comparison of ROSE values with different solvent mixtures and material variations of the CBA |
24 | 5.3.4 Influence by assembly and interconnect technology on measurement of no-clean assemblies Figure 12 – Variation in ROSE values depending on technology used |
25 | Figure 13 – Destructive action of solvent on resin matrix Figure 14 – Comparison of the resin change |
26 | 5.3.5 Ion chromatography of no-clean assemblies CBA Figure 15 – Destructive action of solvent on resin matrix and chipping effect |
28 | Tables Table 1 – List of ions based on IPC-TM650, 2.3.28 [21] |
29 | Table 2 – Fingerprint after ion chromatography of no-clean assembly shown in Figure 16 |
30 | 5.4 Restrictions and limitations of Ionic contamination measurement for cleaned products 5.4.1 Ionic contamination of unpopulated CBs (bare board, state of delivery) Figure 16 – Assembly manufactured with 2x SMT and 1x THT process for the connector |
31 | Figure 17 – Comparison of SPC-charts from 1-year monitoring of different CB suppliers and two different iSn final finish processes |
32 | Figure 18 – Differences in ROSE values for unpopulated CBs depending on the extraction method |
33 | Table 3 – Fingerprint after ion chromatography of bare CBs (state of delivery) |
34 | 5.4.2 Ionic contamination of electronic and electromechanic components Figure 19 – Reduction of ionic contamination on bare CBs (state of delivery from CB supplier) by leadfree reflow step without solder paste or components |
35 | Figure 20 – Influence of components on the ionic contamination based on B52‑standard |
36 | 5.4.3 Ionic contamination of cleaned CBAs Figure 21 – Formation of a white veil or residue on MLCCs during active humidity test |
37 | Table 4 – Fingerprint after ion chromatography of a bare CB and the respective PBA in uncleaned and cleaned condition |
38 | Figure 22 – Chromatogram derived from ion chromatography measurement of a cleaned CBA |
39 | 5.5 How to do – Guidance to use cases 5.5.1 When is the use of ROSE measurements reasonable? Table 5 – Fingerprint after ion chromatography of an uncleaned CBA compared to the cleaned CBA and after removing the components |
41 | 5.5.2 When is the use of ion chromatography reasonable? 5.5.3 At what point in the manufacturing sequence ionic contamination measurements are carried out, if a fingerprint or the basis for process control is to be established? |
42 | 5.5.4 How is the sampling for ROSE and IC done? 5.5.5 How is a product-specific process control limit based on ROSE determined? 5.6 Examples for good practice 5.6.1 Ways to achieve objective evidence |
43 | 5.6.2 Introduction of a new product family with new materials Figure 23 – Approach for achieving objective evidence for a qualified manufacturing process in the automotive industry |
44 | 5.6.3 Adaptation of an ECU for a new vehicle type Figure 24 – ROSE as process control tool |
45 | 6 Surface insulation resistance (SIR) 6.1 SIR – An early stage method to identify critical material combinations and faulty processing 6.2 Fundamental parameters of influence on SIR 6.2.1 General aspects |
46 | Figure 25 – View on SIR measurement |
47 | Figure 26 – Principal course of SIR curves Figure 27 – Response graph concerning stabilized SIR-value after 168 h from a DoE with B53-similar test coupons (bare CB) |
48 | 6.2.2 Influence of climate Figure 28 – SIR measurement with B24-CB, no-clean SMT solder paste |
49 | 6.2.3 Influence of voltage |
50 | 6.2.4 Influence of distance Figure 29 – Increase in ECM propensity depending on voltage applied (U) and Cu-Cu distances (d) of comb structures |
51 | 6.2.5 The limit 100 MΩ and optical inspection Figure 30 – Layout of B53 test coupon |
52 | 6.2.6 Influence of materials |
53 | 6.3 Harmonization of SIR test conditions for characterization of materials for automotive applications 6.4 Different steps of SIR testing 6.4.1 General procedure Table 6 – Common test conditions for basic material evaluation |
54 | 6.4.2 Base material 6.4.3 Solder mask and final finish |
55 | 6.4.4 SMT solder paste 6.4.5 THT fluxes Figure 31 – B53 with solder mask, partially covered and fully covered comb structures |
56 | 6.4.6 Encapsulations and adhesives 6.4.7 Process qualification at CB manufacturer |
57 | 7 Comprehensive SIR testing – B52-approach 7.1 General aspects Table 7 – Recommended SIR test conditions for basic material- and process release for the outer layer manufactured by a CB supplier |
58 | 7.2 The main B52 test board Figure 32 – B52 CBA after SMT process, layout slightly adapted to fulfil company internal layout rules |
59 | 7.3 The test patterns Figure 33 – Pattern of B52 CB, layout slightly adapted to fulfill company internal layout rules |
60 | Table 8 – List of materials for components with recommendations for minor adaptations |
61 | 7.4 Processing of B52 boards 7.5 Sample size for SIR testing of B52 test coupons 7.6 Preparation for SIR testing |
62 | 7.7 Sequence of SIR testing Table 9 – Sequence for SIR testing of B52-CBAs for general material- and process qualification |
63 | Figure 34 – Positive example of comprehensive SIR tests obtained for qualification of a SMT process Figure 35 – Negative example of a contaminated B52-sample, tested by the sequence of constant climate and cyclic damp heat climate |
64 | 7.8 Evaluation 8 Example for good practice 8.1 Methodology for material and process qualification, process control 8.2 Step 1 – Material qualification |
65 | Figure 36 – SIR test coupon, similar to B53, for principal material qualification Figure 37 – SIR test with constant climate and cyclic damp heat condition |
66 | 8.3 Step 2 – Product design verification and process validation Figure 38 – B52 test board and example of SIR curve Figure 39 – Example of the product that was realized by the released materials and process |
67 | 8.4 Step 3 – Definition of process control limits Figure 40 – Ionic contamination test results from 4 repetitions of PV samples Figure 41 – Results of ionic residue testing and calculation of upper control limit (UCL) |
68 | Figure 42 – Run chart derived from 2 samples per month during mass production |
69 | Annex A (informative)SIR measurement for SMT solder paste – Representative example A.1 Purpose A.2 Equipment A.3 Example of an instruction how to perform the test |
72 | Bibliography |