🔥🔥 Don’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.

🔍
BSI PD IEC/TR 62866:2014

BSI PD IEC/TR 62866:2014

$215.11

Electrochemical migration in printed wiring boards and assemblies. Mechanisms and testing

Published By Publication Date Number of Pages
BSI 2014 96
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. We’re here to assist you 24/7.
Email:[email protected]

This Technical Report describes the history of the degradation of printed wiring boards caused by electrochemical migration, the measurement method, observation of the failure and remarks to testing in detail.

PDF Catalog

PDF Pages PDF Title
4 English
CONTENTS
9 FOREWORD
11 INTRODUCTION
12 1 Scope
2 Electrochemical migration
2.1 Operation failure of electronic and electric equipment
Figures
Figure 1 – Main causes of insulation degradation in electronic equipment
13 2.2 Name change of migration causing insulation degradation and nature of the degradation
2.2.1 History of naming with migration causing insulation degradation
2.2.2 Process of degradation by migration
2.3 Generation patterns of migration
14 Figure 2 – Generation patterns of migration
15 3 Test conditions and specimens
3.1 Typical test methods
Tables
Table 1 – Standards for migration tests
16 3.2 Specimens in migration tests
3.2.1 Design of test specimens
Figure 3 – Basic comb pattern
17 Figure 4 – Comb type fine pattern
Table 2 – Standard comb type pattern (based on IPC-SM-840)
Table 3 – Comb fine pattern (based on JPCA BU 01)
18 Figure 5 – ECM group comb type pattern (mm)
Figure 6 – Comb pattern for insulation resistance of flexible printed wiring board
19 Figure 7 – Insulation evaluation pattern for through-holes and via holes
20 Figure 8 – Details of the insulation evaluation pattern of Figure 7 (cross section of 4 and 5)
Figure 9 – Test pattern of the migration study group
Table 4 – Dimension of insulation evaluation pattern for through-holes
21 3.2.2 Specifications and selection of specimen materials
22 3.2.3 Remarks on the preparation of specimens
3.2.4 Storing of specimens
3.2.5 Pretreatment of the specimen (baking and cleaning)
23 3.2.6 Care to be taken in handling specimens
3.3 Number of specimens required in a test
3.3.1 Specifications given in JPCA ET 01
Table 5 – Surface pretreatment to printed wiring board
24 3.3.2 Number of specimens in a test
3.3.3 Number of specimens for the different evaluation purposes of a test
Table 6 – Number of specimens (JPCA ET 01)
Table 7 – Approximate number of specimens required depending on the purpose of the test
25 4 Test methods
4.1 General
4.2 Steady state temperature and humidity test and temperature-humidity cyclic test
4.2.1 Purpose and outline of the test
26 4.2.2 Test profile
Figure 10 – Recommended profiles of increasing temperature and humidity
27 Figure 11 – Humidity cyclic profile (12 h + 12 h)
28 Figure 12 – Profiles of combined temperature-humidity cyclic test
29 4.2.3 Test equipment
Figure 13 – Structure of steady state temperature-humidity test equipment
30 4.2.4 Remarks on testing
31 Figure 14 – Specimen arrangement and air flow in test chamber
Table 8 – Ionic impurity concentration of wick (10–6)
32 4.3 Unsaturated pressurized vapour test or HAST (highly accelerated temperature and humidity stress test)
4.3.1 Purpose and outline of the test
Figure 15 – Effective space in a test chamber
33 4.3.2 Temperature-humidity-pressure profile
Figure 16 – HAST profile
34 4.3.3 Structure of and remarks on the test equipment
Figure 17 – Two types of HAST equipment and their structures
35 Figure 18 – Difference in failure time among different test laboratories
36 4.3.4 Remarks on performing HAST
Figure 19 – Colour difference of specimen surface among different laboratories (130 °C/85 %RH/DC 50 V)
Table 9 – Insulation covering materials for cables for voltage application
37 Figure 20 – Resistance and pull-strength of cables used in HAST (130 °C 85 %RH)
38 4.4 Saturated and pressurized vapour test
4.4.1 Purpose and outline of the test
4.4.2 Test profile
4.4.3 Remarks on test performing
39 4.5 Dew cyclic test
4.5.1 Purpose and outline of the test
4.5.2 Dew cycle test temperature-humidity profile
Figure 21 –Difference between unsaturated and saturation control of PCT equipment (relative humidity and average failure time)
40 4.5.3 Structure of the test equipment
4.5.4 Remarks on the test method
Figure 22 – Temperature-humidity profile of dew cycle test
Table 10 – Dew cycle test condition
41 Figure 23 – Structure of dew test equipment
42 Figure 24 – Dew-forming temperature and dew size
43 4.5.5 An example of migration in the solder flux from the dew cycle test
Figure 25 – Board surface at the best dew formation condition
Table 11 – Dew formation condition and dew size
Table 12 – Dew cycle test condition
44 Figure 26 – Surface state before test
Figure 27 – Surface state after 27 h
Figure 28 – SEM image of specimen surface after the test
45 4.6 Simplified ion migration tests
4.6.1 General
4.6.2 De-ionized water drop method
Figure 29 – Element analysis of the surface after the test
46 Figure 30 – Circuit diagram of water drop test
Figure 31 – Migration generated in the water drop test
47 4.6.3 Diluted solution method
Figure 32 – Electroerosion test method using the diluted solution
48 4.7 Items to be noted in migration tests
Figure 33 – Current and concentration of electrolytic solution
Figure 34 – Precipitation on a specimen and its element analysis
49 Table 13 – Water quality for test
Table 14 – Water quality change in steady-state temperature-humidity test (10–6)
50 Table 15 – Ionic impurities in voltage applying cables (10–6)
51 5 Electrical tests
5.1 Insulation resistance measurement
5.1.1 Standards of insulation resistance measurement
5.1.2 Measurement method of insulation resistance
Table 16 – Standards of insulation resistance measurement
52 Figure 35 – An example of insulation resistance measurement outside of the chamber
53 Figure 36 – Circuit diagram of insulation resistance measurement
54 5.1.3 Special remarks on insulation resistance measurement
Figure 37 – Examples of leakage current characteristics
55 Figure 38 – Relationship insulation resistance with charging time of capacitor mounted boards
Figure 39 – Comparison of insulation resistance measurement inside and outside a test chamber
56 Figure 40 – Relative humidity and insulation resistance
57 5.2 Measurement of dielectric characteristics
5.2.1 General
5.2.2 Dielectric characteristics of board surface
Figure 41 – Effect of interruption of measurement on insulation resistance (variation of insulation resistance with the time left in atmospheric environment)
58 5.2.3 Migration and dielectric characteristics of the printed wiring board surface
59 Figure 42 – Frequency response of dielectric characteristics of printed wiring board
Figure 43 – Temperature response of dielectric characteristics of printed wiring board
60 Figure 44 – Changes of static capacitance and tan δ
of a specimen through a deterioration test
61 5.2.4 Evaluation of migration by AC impedance measurement
Figure 45 – Test procedure of a dielectric characteristics test
Figure 46 – Comparison of dielectric characteristics of two types of flux
62 6 Evaluation of failures and analysis
6.1 Criteria for failures
Figure 47 – Measurement principle of EIS (Electrical Insulation System)
Figure 48 – Gold (Au) plating, non-cleaning
63 6.2 Data analysis
6.2.1 Analysis of experimental data
Figure 49 – Bath tub curve
Table 17 – Criteria of migration failure by insulation resistance
65 6.2.2 Relationship of the parameters in the experimental data and an example of the analysis
66 6.2.3 Electric field strength distribution
Figure 50 – Relation between the variation of insulation resistanceand the weight changes by water absorption
67 6.3 Analysis of specimen with a failure, methods of analysis and case study
6.3.1 General
Figure 51 – Distribution of electric field between line and plane
Figure 52 – Distribution of the electric field between lines
68 6.3.2 Cross section
Figure 53 – Different observations of the same dendrite according todifferent cross section cutting planes
70 Figure 54 – An example of angle lapping
71 Figure 55 – Structure analysis of an angle lapped solder resist in the depth direction
72 6.3.3 Optical observation
Table 18 – Various methods for optical observation of failures
74 6.3.4 Analysis methods
6.3.5 Defect observation and analysis
Table 19 – Various methods for defect analysis
75 Figure 56 – Observed images of dendrite with different illumination methods (without solder resist)
Figure 57 – EPMA analysis of migration (dendrite) on a comb type electrode
76 Figure 58 – EPMA analysis of migration (dendrite) in the solder resist
77 Figure 59 – 3D shape measuring system
Figure 60 – Electrodes which migration was generated
78 Figure 61 – 3D observation of electrodes before and after the test
79 6.4 Special remarks on the migration phenomenon after the test
Figure 62 – 3D observation of dendrite
Table 20 – Board specification and test conditions
80 Table 21 – Effect of the overlap of electrodes
Table 22 – Effect of the area of the conductor
81 Table 23 – Effect of the shape of the tip of the electrodes
82 Annex A (informative) Life evaluation
A.1 Voltage dependence of life
A.2 Temperature dependence of life
A.3 Humidity dependence of life
A.3.1 General
83 A.3.2 Relation between temperature (°C), relative humidity ( %RH) and vapour pressure (hPa)
A.4 Acceleration test of life and acceleration factor
Figure A.1 – Temperature and saturated vapour pressure
Table A.1 – Vapour pressure at test temperature and relative humidity
84 A.5 Remarks
85 Annex B (informative) Measurement of temperature-humidity
B.1 Measurement of temperature and humidity
B.1.1 General
B.1.2 Commonly used temperature-humidity measurement systems and their merits
B.1.3 Requirements for the humidity measurements in a steady-state temperature-humidity test chamber
B.2 Typical methods of temperature and humidity measurement
B.2.1 General
86 B.2.2 Checking procedure for temperature measurement
Table B.1 – Merits of and remarks on various humidity measuring methods (applicable to steady state temperature-humidity tests)
87 B.2.3 Checking procedure for humidity measurement
Figure B.1 – Specification of sensors used in the test and their shapes
88 B.2.4 Derivation of temperature in a chamber
Figure B.2 – Calculation method of the average temperature (humidity), the average maximum temperature (humidity) and the average minimum temperature (humidity)
89 B.2.5 Definition of relative humidity in HAST
Table B.2 – Derivation of relative humidity from dry-and-wet bulb humidity meter
90 Figure B.3 – Relative humidity in a pressurized chamber
91 Bibliography

Related products

BSI PD IEC/TR 62866:2014
$215.11