1. SMTA Southeast Asia Technical Conference April 15-16, 2015

2. ELECTRONIC CLEANING FLUID ADVANCEMENTS Presented By Jason Chan Kyzen Corporation

3. Introduction Electronic Hardware Innovations Problem Statement Exposed Metal Corrosion Potential Advanced Cleaning Agent Designs Experimental Inference from Data Findings Matching Cleaning Agent to the Process Agenda

4. INTRODUCTION

5. More interconnects Higher density Tighter pitch Low standoffs Mixed metals Modern Electronics

6. Residue trapped under BTCs Ionics in flux residue can exacerbate – Contamination levels under part – Flux Bridging – Creation of high resistance shorts across pads Insufficiently Cleaned Component

7. Surface - Yes / BTC - No Looks Can Be Deceiving Parts Removed with Heat Only Residue Pool Across Pads!!!

8. Dendrites (in Electronics) – Metallic tree-branch-like projection that passes current along an unintended path – Typically Constructed of Metal Ions How Dendrites are Formed/Grown Leakage Currents PCB + + + + + ++ ++++++ ++ +++ Liquid Carrier +- ++++ +++++ Applied Voltage Migrating Metal Ions Metal Ions Board Terminations

9. Harder to clean Longer time in wash May impact metal and material compatibility Cleaning Highly Dense Assemblies

10. ELECTRONIC HARDWARE INNOVATIONS

11. Challenges – Processor and memory functions – Electronic interconnection system – Cleaning process Substrate – Key enabler – Array configured packaging – Smaller footprints – Progressively smaller outline – Mixed metal exposure Increased Signal Speed

12. Mixed Metals – Cu / Al / SAC LEDs

13. Al/Cu Pads

14. Copper Wire Bonds

15. Copper Pillar

16. Memory

17. PROBLEM STATEMENT

18. Require specialized materials Different alloy combinations The problem is some reactive metals exposed to the cleaning process can be Oxidized Etched Attacked There is a need for advanced cleaning fluid designs that are – Multi-metal safe – Effective at cleaning soils Electronic Circuit Innovations

19. EXPOSED METAL CORROSION POTENTIAL

20. Can affect exposed metals – Electrochemical deterioration – Chemical attack May affect – Reliability – Uninterrupted operation of electric components Harsh Cleaning Agents

21. 4 essential factors – Anode – Cathode – Electrical connection between cathode and anode for the electron current flow – Electrolyte to facilitate ionic movement Corrosion Theory

22. Anodic reaction – Metal dissolution – Formation of electrons Cathodic reaction – Metals attracted to cathode – Metal forms a dendrite and grows toward anode Charges are balanced Tighter spacing increases risk of dead short Anodic / Cathodic Reaction

23. 1.Change to a more suitable cleaning agent 2.Modifications to the environment 3.Use of protective coatings 4.Application of cathodic and anodic protection 5.Design modifications to the system or component Minimizing Corrosion Failures

24. ADVANCED CLEANING FLUID DESIGNS

25. Material Compatibility Factors

26. SOLVENTACTIVATORBUFFER SURFACTANT INHIBITOR Cleaning Fluid Technology Cleans Soils Material Compatibility Wide Process Window Low Cost of Ownership Removal of soils under BTCs No attack to exposed metals Dissolves Contaminants Softens contaminants for better dissolving in the solvent Maintains a very stable pH Reduces the surface tension for better penetration Protects all sensitive metals from corrosion or etch

27. Important driving force for o Solvating non-polar resins, rosin, and polymers Rate of dissolution depends on … o Matching up to the flux residue o Wash concentration o Wash temperature o Wash time o Impingement energy Solvency

28. Organic or Inorganic compounds with functional groups – Containing a polar atom – Weak or strong base Activators

29. Van der Waals force – Attractive / Repulsive forces between molecules – Example: Rosin flux reacts with a basic cleaning solution Converts rosin into a water soluble soap London Dispersive force – Intermolecular force – Induces a dipole / dipole interaction – Example: Induces a dipole on non-polar no clean flux residues to improve dissolution Activator Drivers

30. Strongly buffered solutions increase bath life Bath Life

31. Multi-functional ingredients that – Lower surface tension – Wet the surface Needed to penetrate low gaps – Detergency Hydrophobic ~ non-polar loving Hydrophilic ~ polar loving Surfactants

32. Improves the ability of the cleaning agent to penetrate and wet soil Wetting DI Water Cleaning agent in DI Water

33. Corrosion Mechanism Metal surface immersed in an electrolyte – Alkaline cleaning agent in water – Metal ions tend to be lost from the metal into the electrolyte – Leaves electrons behind on the metal – Continues to occur until the metal reaches its equilibrium potential – Longer exposure results in more and more metal ions being lost, resulting in continuous corrosion of the metal

34. Corrosion Inhibition 1. Inhibitor is adsorbed on the metal surface – Process of chemisorption / physisorption – Forms thin protective film in conjunction with metallic ions 2. Protective film over the metal – High solids rosin flux coats alloy during cleaning 3. Inhibitor ties up corrosive substance in water

35. EXPERIMENTAL

36. SEM analysis of – SAC 305 – Ni layer – Cu Pillar – Al Pad 10 min. soak 7% 60˚C Copper Pillar Die Selected

37. Cleaning Agents Evaluated

38. Cleaning Agent #1

39. Cleaning Agent #2

40. Cleaning Agent #3

41. Cleaning Agent #4

42. Cleaning Agent #5

43. Summary of Data Findings

44. INFERENCES FROM DATA FINDINGS

45. Equilibrium phase in an aqueous solution – No reaction – Immunity / Passive range Metals can react based on – pH of the solution Some metals are more reactive Some stable at different pH levels Some react with water Other react slowly in water – Vigorously with acid or bases Metals

46. Al pad is the most reactive metal Al reacts with acids and bases – Stable oxide or coating reduces attack SAC305 – Pitting corrosion from highly basic solutions Cu Pillar – Oxidizes from highly basic solutions Ni – No effect from highly basic solutions Copper Pillar Die

47. Adsorbs on the metal surface – Forms a protective film Form an oxide on metal – Protective film reduces corrosion effect Improves immunity Alloy specific Corrosion Inhibition

48. Improve cleaning effects – Attractive forces – Oxidation / Reduction – Induces a Dipole on No-Clean flux residues In the absence of these attractive forces – Reduces cleaning effects – Some soils not cleanable in an aqueous solution Low levels reduces bath life Polar Activators

49. Industry standards – Excellent cleaning on all soil types – Engineered Corrosion Inhibition Data Finds – Good Compatibility SAC305 Ni Cu – Corrosion potential found on Al Cleaning Agent 1 & 3

50. Neutral range cleaning agents – Low Levels of Polar Activators – Less Reactive to Exposed Metals – May not be as effective on some flux residues – Bath life will be shorter Data Finds – Good Compatibility SAC305 Ni Cu Al Cleaning Agent 2 & 5

51. Saponified cleaning agent – High levels of polar activators – Greater potential to attack exposed metals Data Finds – Good Compatibility Ni – Poor Compatibility SAC305 Cu Al Cleaning Agent 4

52. MATCHING CLEANING AGENT TO THE PROCESS

53. Engineered cleaning agent matched to – Part being cleaned – Soils – Cleaning machine Key factors – Exposed metals – Interaction potential with the cleaning process – Residue properties – Cleaning machine – Z-Axis under Bottom Termination – Advanced Cleaning Fluids design to clean under these factors Matching Cleaning Agent to Process

54. Thank You 54 Dr. Mike Bixenman CTO, Kyzen Corporation mikeb@kyzen.com mikeb@kyzen.com Jason Chan Technology Manager, Asia jason_chan@kyzen.com jason_chan@kyzen.com Haley Jones Chemist haley_jones@kyzen.com haley_jones@kyzen.com Chelsea Jewell Science/Application Technician chelsea_jewell@kyzen.com chelsea_jewell@kyzen.com TC Loy Sales Mgr. Malaysia tc_loy@kyzen.com tc_loy@kyzen.com