BSI PD IEC TR 60068-3-12:2022 – TC
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Tracked Changes. Environmental testing – Supporting documentation and guidance. Method to evaluate a possible lead-free solder reflow temperature profile
| Published By | Publication Date | Number of Pages |
| BSI | 2022 | 90 |
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 54 | undefined |
| 56 | CONTENTS |
| 58 | FOREWORD |
| 60 | INTRODUCTION |
| 61 | 1 Scope 2 Normative references 3 Terms and definitions 4 Determination of an envelope reflow profile 4.1 Temperature-time-envelope curve |
| 62 | 4.2 Diagram of a theoretical envelope reflow profile 4.3 Key parameters of the envelope reflow profile Figures Figure 1 – Schematic envelope reflow profile Tables Table 1 – Temperature-time curve – Units |
| 63 | Table 2 – Envelope points of a reflow temperature-time-profile |
| 65 | 5 Temperature profile measurements 5.1 Determining the measurement locations |
| 66 | 5.2 Selection and attachment of thermocouples 5.2.1 Types of thermocouples Figure 2 – Recommended temperature measurement locations on a test board Figure 3 – X-ray of a sheath thermocouple |
| 67 | 5.2.2 Preparation of thermocouples 5.2.3 Attachment of thermocouples Figure 4 – Example of a) acceptable and b) unacceptable attachment of the thermocouples |
| 68 | Table 3 – Thermocouple attachment methods |
| 69 | Figure 5 – Examples of good and bad thermocouple attachment |
| 70 | 5.2.4 Influence of attachment method and operator on measurement results 5.3 Temperature gradient 5.3.1 Gradient calculation Figure 6 – Thermocouples (TC) fixed to an LED Figure 7 – Results of the same test board prepared by different methods |
| 71 | Figure 8 – Gradient calculation |
| 72 | 5.3.2 Sampling rate 5.4 Analysis, comparison and overlay of different reflow profiles and best practice Figure 9 – Example of a gradient calculation on a temperature-time curve |
| 73 | 5.5 Measuring equipment 6 Tolerance analysis of the measurement chain Figure 10 – Overlay of different reflow profiles (origin at oven entry) Figure 11 – Overlay of different reflow profiles (overlap at start of peak zone) |
| 74 | Figure 12 – Measurement chain Table 4 – Tolerances of the temperature measurement chain |
| 75 | 7 Optimizing a temperature profile 7.1 General procedure 7.2 Description of a typical test board and the used reflow oven |
| 76 | 7.3 Schematic envelope reflow profile for the example board Figure 13 – Description of a test board (electronic assembly) |
| 77 | Table 5 – Envelope points at the envelope reflow profile for the test board |
| 78 | 7.4 Preparation of test board Figure 14 – Envelope reflow profile for the test board Figure 15 – Thermal images of the test board after cooling down from 150 °C |
| 79 | 7.5 Possibility of temperature profiling optimization with simulation tools Table 6 – Measurement locations on the sample assembly |
| 80 | Figure 16 – Geometric and thermal description of the test board Figure 17 – Geometric and thermal description of the reflow soldering equipment |
| 81 | 7.6 Iteration steps for finding reflow equipment setup Figure 18 – Predicted reflow profile with help of simulation (blue band) |
| 82 | Table 7 – Settings according to experience Table 8 – Measurement results for the settings from Table 7 Table 9 – Settings for second run Table 10 – Measurement results for the settings from Table 9 |
| 83 | Figure 19 – Overlay envelope curves of the temperature-time curvesof three profiling steps, 0201-chip solder joint Table 11 – Settings after adjustment of the heating zone temperatures Table 12 – Measurement results from Table 11, adaptation of heating zone temperatures |
| 84 | 8 Examples of envelope reflow profiles 8.1 Key data for two different solders Figure 20 – Overlay envelope curves of the temperature-time curvesof three profiling steps, ERU25 solder joint |
| 85 | 8.2 Example of a qualification temperature profile for component used in lead-free reflow soldering (SAC) Table 13 – Examples for envelope reflow profile key data for two different solders |
| 86 | Figure 21 – Exemplary qualification reflow temperature profile for the qualification of components intended for use in assemblies with a wide variation of thermal masses Table 14 – Key parameters for a lead-free SAC reflowtemperature profile for component qualification |
| 87 | Bibliography |
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BSI PD IEC TR 60068-3-12:2022
Environmental testing – Supporting documentation and guidance. Method to evaluate a possible lead-free solder reflow…
