Performance Of Pb Free Solder Pastes At Different Reflow

3,084 views

Published on

Published in: Business, Technology
0 Comments
4 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
3,084
On SlideShare
0
From Embeds
0
Number of Embeds
11
Actions
Shares
0
Downloads
107
Comments
0
Likes
4
Embeds 0
No embeds

No notes for slide

Performance Of Pb Free Solder Pastes At Different Reflow

  1. 1. Performance of Pb-free Solder pastes at different reflow profiles
  2. 2. Primary Objective <ul><li>To analyze the defects of Pb-free solder pastes from two different manufacturers, subjected to three different reflow profiles, viz., </li></ul><ul><ul><li>In-Spec Profile </li></ul></ul><ul><ul><li>Above-Spec Profile </li></ul></ul><ul><ul><li>Below-Spec Profile </li></ul></ul>
  3. 3. Secondary Objective <ul><li>To come up with the above said reflow profiles based on the two different solder paste manufacturer’s specification sheets. </li></ul><ul><li>The two solder pastes selected were, </li></ul><ul><ul><li>Alpha OM-338-T Pb-free </li></ul></ul><ul><ul><li>Indium 5.1 Pb-Free </li></ul></ul>
  4. 4. Alpha Pb-free Specification <ul><li>Ramp Rate : 0.8°C to 1.7 o C/Second </li></ul><ul><li>Soak Temp : 130°C to Liquidus </li></ul><ul><li>TAL : 35 - 90 sec </li></ul><ul><li>Peak Temp : 232-250 o C </li></ul>
  5. 5. Indium 5.1 Pb-free Specification <ul><li>Ramp Rate : 0.5°- 2.0°C/Second </li></ul><ul><li>Soak Temp : 200°-210°C </li></ul><ul><li>TAL : 30 - 90 sec </li></ul><ul><li>Peak Temp : 229-260 o C </li></ul>
  6. 6. Project Description <ul><li>The above mentioned Pb-free solder pastes are subjected to three different profiles. </li></ul><ul><li>The performance of each paste is analyzed by examining the possible defects. </li></ul><ul><li>The defects are then superimposed on the reflow profile explaining the reasons for their occurrence. </li></ul>
  7. 7. Profiling Procedure <ul><li>The paste and the reflow specification are collected from the paste manufacturer specification document. </li></ul><ul><li>The three different reflow recipes for the Pb-free solder pastes are then generated. </li></ul><ul><li>The zone temperature and the conveyor speed for each specification of each paste are noted down. </li></ul><ul><li>The thermocouple-attached copper coupons are used for profiling. </li></ul>
  8. 8. Alpha Reflow Statistics Profile Ramp Rate (°C/Sec) Soak Temperature TAL (Seconds) Peak Temp (°C) Alpha Above-Spec 2.8 130 °C to 217 °C 134.7 270.5 Alpha In-Spec 1.2 130 °C to 217 °C 64.3 241.4 Alpha Below Spec 1.1 130 °C to 217 °C 19.6 220.2
  9. 9. Zone Temperatures for Alpha Paste Profile Conveyor Speed Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Alpha Above-Spec 38 153 187 212 249 268 281 Alpha In-Spec 36 86 116 148 193 235 256 Alpha Below Spec 35 65 94 124 164 201 240
  10. 10. Alpha Reflow Profiles
  11. 11. Indium Reflow Statistics Profile Ramp Rate (°C/Sec) Soak Temperature TAL (Seconds) Peak Temp (°C) Indium Above-Spec 1.7 200 °C to 210°C 124.5 268.1 Indium In-Spec 1.3 200 °C to 210°C 62.5 239.7 Indium Below-Spec 1.1 200 °C to 210°C 7 218.2
  12. 12. Zone Temperatures for Indium Paste Profile Conveyor Speed Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Indium Above-Spec 29 125 166 205 211 257 282 Indium In-Spec 31 104 139 173 217 201 254 Indium Below-Spec 35 84 110 130 161 190 240
  13. 13. Indium Reflow Profiles
  14. 14. Reflow Procedure <ul><li>The Pb-free solder paste is pasted on the copper coupons using a 0.25 in diameter stencil aperture. </li></ul><ul><li>The first printed copper coupon was subjected to reflow with a Above-Spec profile recipe for both pastes. </li></ul><ul><li>The second printed copper coupon was subjected to reflow with an In-Spec profile recipe for both pastes. </li></ul><ul><li>The third printed copper coupon was subjected to reflow with a Below-Spec profile recipe for both pastes. </li></ul>
  15. 15. Reflow Procedure <ul><li>The images of the copper coupons are taken after reflow. </li></ul><ul><li>The performance of the solder paste in all the three profiling conditions are analyzed by examining the possible defects using, </li></ul><ul><ul><li>Magnifying scope </li></ul></ul><ul><ul><li>X-Ray </li></ul></ul><ul><li>The images of the defects are captured and further analyzed. </li></ul>
  16. 16. Defects Analysis
  17. 17. Anticipated Defects <ul><ul><li>Solder Balling </li></ul></ul><ul><ul><li>Colder Solder </li></ul></ul><ul><ul><li>Voiding </li></ul></ul><ul><ul><li>Blow Holes </li></ul></ul><ul><ul><li>Non-Wetting </li></ul></ul><ul><ul><li>De-Wetting </li></ul></ul><ul><ul><li>Poor Wetting </li></ul></ul><ul><ul><li>Pin holes </li></ul></ul><ul><ul><li>Porous Solder </li></ul></ul><ul><ul><li>Disturbed Solder </li></ul></ul><ul><ul><li>Solder Spatter </li></ul></ul><ul><ul><li>Scratches </li></ul></ul><ul><ul><li>Oxidation </li></ul></ul>
  18. 18. Solder Balling <ul><li>Small spheres of solder that remain on the board after reflow soldering adhering to the board. </li></ul><ul><li>Solder Balling was seen in </li></ul><ul><ul><li>Alpha Above-Spec </li></ul></ul><ul><ul><li>Alpha Below-Spec </li></ul></ul><ul><ul><li>Indium Above-Spec </li></ul></ul><ul><ul><li>Indium Below-Spec </li></ul></ul>
  19. 19. <ul><li>Indium Above-Spec </li></ul><ul><li>Alpha Above-Spec </li></ul>Solder Balling Solder Balling Solder Balling
  20. 20. <ul><li>Alpha Below Spec </li></ul><ul><li>Indium Below-Spec </li></ul>Solder Balling Solder Balling Solder Balling
  21. 21. Solder Balling <ul><li>The possible reasons for Solder Balling could be </li></ul><ul><ul><li>Preheat temperature too low / high </li></ul></ul><ul><ul><li>Preheat ramp up rate high </li></ul></ul><ul><ul><li>Excessive heating rate </li></ul></ul><ul><ul><li>Solder paste viscosity too low </li></ul></ul><ul><ul><li>Solder paste oxidation </li></ul></ul>
  22. 22. Cold Solder <ul><li>A solder joint with poor wetting and a grayish porous appearance is called as Cold Solder. </li></ul><ul><li>Cold Solder was seen in </li></ul><ul><ul><li>Indium Below-Spec </li></ul></ul>
  23. 23. <ul><li>Indium Below-Spec </li></ul><ul><li>Indium Below-Spec </li></ul>Cold Solder Soldered Region Cold Solder Cold Solder
  24. 24. Cold Solder <ul><li>The possible reasons for Cold Solder could be </li></ul><ul><ul><li>Insufficient heat </li></ul></ul><ul><ul><li>In adequate cleaning </li></ul></ul><ul><ul><li>Excessive impurities in solder </li></ul></ul><ul><ul><li>Poor fluxing action </li></ul></ul><ul><ul><li>Low cooling rate </li></ul></ul>
  25. 25. Non-Wetting <ul><li>A condition whereby a surface has contacted molten solder , but the solder has not adhered to all surface leaving the base metal exposed is called as Non-Wetting </li></ul><ul><li>Non-Wetting was seen in </li></ul><ul><ul><li>Indium Above-Spec </li></ul></ul><ul><ul><li>Alpha Above-Spec </li></ul></ul>
  26. 26. <ul><li>Indium Above-Spec </li></ul><ul><li>Alpha Above-Spec </li></ul>Non-Wetting Non-Wetting
  27. 27. Non-Wetting <ul><li>The possible reason for Non-Wetting is </li></ul><ul><ul><li>Preheat temperature high </li></ul></ul><ul><ul><li>Reflow Temperature too low </li></ul></ul><ul><ul><li>Presence of physical barrier between surfaces to be joined </li></ul></ul><ul><ul><li>Solder paste oxidation </li></ul></ul>
  28. 28. Dewetting <ul><li>Dewetting is a condition that results when molten solder coats a surface and then recedes to leave irregularly-shaped mounts of solder and has an appearance of water on greasy surface. </li></ul><ul><li>Dewetting was seen in </li></ul><ul><ul><li>Indium Above-Spec </li></ul></ul><ul><ul><li>Alpha Above-Spec </li></ul></ul>
  29. 29. <ul><li>Indium Above-Spec </li></ul><ul><li>Alpha Above-Spec </li></ul>Dewetting Dewetting
  30. 30. Dewetting <ul><li>The possible reason for Dewetting is </li></ul><ul><ul><li>Excessive Reflow temperature </li></ul></ul><ul><ul><li>Excessive heating rate </li></ul></ul><ul><ul><li>Board contamination </li></ul></ul>
  31. 31. Flux Splatter <ul><li>Flux Splatter is a condition where we find the flux is splattered around the solder, creating aesthetic issues. </li></ul><ul><li>Flux Splatter was seen in </li></ul><ul><ul><li>Indium Above-Spec </li></ul></ul><ul><ul><li>Alpha Above-Spec </li></ul></ul><ul><li>The possible reason for Flux Splatter is </li></ul><ul><ul><li>Improper process parameter (Heat / Moisture) </li></ul></ul>
  32. 32. <ul><li>Indium Above-spec </li></ul><ul><li>Indium Above-Spec </li></ul>Flux Spatter Flux Spatter
  33. 33. Craters <ul><li>Craters are formed due to the out gassing of various volatile substances and moisture present in the solder paste, creating aesthetic issues. </li></ul><ul><li>Craters were seen in </li></ul><ul><ul><li>Alpha Above-Spec </li></ul></ul><ul><ul><li>Alpha In-Spec </li></ul></ul><ul><ul><li>Alpha Below-Spec </li></ul></ul><ul><li>The possible reason for Crater formation is </li></ul><ul><ul><li>Out Gassing of volatile substances and moisture. </li></ul></ul>
  34. 34. <ul><li>Alpha Above-Spec </li></ul><ul><li>Alpha In-Spec </li></ul>Craters Crater Craters
  35. 35. <ul><li>Alpha Below-Spec </li></ul><ul><li>Alpha Below-Spec </li></ul>Craters Crater Crater
  36. 36. Flux Charring <ul><li>Due to excessive heat, the flux starts charring and gets deposited on to the board and also blackening of the board occurs, creating aesthetic issues. </li></ul><ul><li>The Flux Charring is seen in </li></ul><ul><ul><li>Indium Above-Spec </li></ul></ul><ul><ul><li>Alpha Above-Spec </li></ul></ul><ul><li>The possible reason for Flux Charring is </li></ul><ul><ul><li>Excessive heat </li></ul></ul>
  37. 37. <ul><li>Alpha Above-Spec </li></ul><ul><li>Indium Above-Spec </li></ul>Flux Charring Flux charring Flux charring
  38. 38. Scratches <ul><li>Scratches are formed on the surface of the solder surface due to poor handling of components during cleaning and other processes, causing aesthetic issues. </li></ul><ul><li>Scratches were seen in all the specifications due to poor handling occurred during cleaning. </li></ul>
  39. 39. Uneven Surfaces <ul><li>Uneven surfaces are formed due to the out gassing of various volatile substances and moisture present in the solder paste, creating aesthetic issues. </li></ul><ul><li>Uneven Surfaced were seen in </li></ul><ul><ul><li>Alpha Above-Spec </li></ul></ul><ul><ul><li>Alpha In-Spec </li></ul></ul><ul><li>The possible reason for Uneven surface formation is </li></ul><ul><ul><li>Out Gassing of volatile substances and moisture. </li></ul></ul>
  40. 40. <ul><li>Alpha In-Spec </li></ul><ul><li>Alpha Above-Spec </li></ul>Uneven Surfaces
  41. 41. Oxidation <ul><li>Oxidation of solder occurs due to the excessive heat in the oven, which is seen outside as a blackened surface causing aesthetic issues. </li></ul><ul><li>Oxidation is seen in </li></ul><ul><ul><li>Indium Above-Spec </li></ul></ul><ul><ul><li>Indium In-Spec </li></ul></ul>
  42. 42. <ul><li>Indium Above-Spec </li></ul><ul><li>Indium In-spec </li></ul>Oxidation
  43. 43. Por
  44. 44. Comparison of three specification <ul><li>While comparing the three profiles, The In-Spec solder is too shiny than the other two profiles. </li></ul>In-Spec Below-Spec Above-Spec

×