TT COST MP0602 meeting, Brno “MatPack” – deposition, modelling and characterisation of high melting point lead-free micro solders Peter T. Tang IPU

TT COST MP0602 meeting, Brno MatPack Concept and Subprojects 3D-modelling of phase formation Prediction of solder properties Focused Ion Beam preparations SEM imaging and composition analysis Phase quantification by x-ray diffraction Determination of melting point Metrology Life cycle assessment and toxicology PVD of diffusion barriers Electroplating of alloys Deposition of multi-layers

TT COST MP0602 meeting, Brno High Melting Point Solder Applications High melting point solder Low melting point solder (SnAgCu, 217 °C) High melting point = Low melting point plus 50 °C or more! Ref EC exemptions, final report (ERA Technology)

TT COST MP0602 meeting, Brno Solder Deposition

TT COST MP0602 meeting, Brno Electroplating Processes The following electroplating processes are established at IPU: SnZn (9% Zn)Commercial process, SLOTOLOY ZSN Melting point (eutectic) 198 ºC SnCu (0.7% Cu)Commercial process, Yuken Melting point (eutectic) 217 ºC SnCu (3% Cu)Semi-commercial process, Yuken Melting range ºC AnSn (20% Sn)Commercial process, Technic AuroStan H Melting point (eutectic) 278 ºC Pure Au and Pure SnAvailable in several versions

TT COST MP0602 meeting, Brno Well-known Pb-Sn Solders 183°C~315°C

TT COST MP0602 meeting, Brno SnCu Phase Diagram

TT COST MP0602 meeting, Brno Elements that can be deposited

TT COST MP0602 meeting, Brno Multi-layers or Composition Modulated Alloys

TT COST MP0602 meeting, Brno Tin-silver Alloys for Soldering Advantages:  Mildly alkaline electrolyte (pH=9) compatible with photoresist  No “whiskers” tendency due to a silver content of 3.8 At.%  No phase transformation at low temperatures (13 °C)  Melting point approximately 10 °C lower than pure tin  Relatively “safe” bath

TT COST MP0602 meeting, Brno Phase Diagram of Tin-silver

TT COST MP0602 meeting, Brno Electrolyte Composition Triethanolamine Tin chloride Potassium pyrophosphate Silver iodide Triethanolamine Potassium iodide SnCl 2 · 2 H 2 O K2P2O7K2P2O7 KI AgI C 6 H 15 NO M Room temperature pH = 9.3

TT COST MP0602 meeting, Brno Surface Without TEA

TT COST MP0602 meeting, Brno Rotating Cylinder Electrode

TT COST MP0602 meeting, Brno Silver Concentration

TT COST MP0602 meeting, Brno Rotational Speed

TT COST MP0602 meeting, Brno Bath Temperature

TT COST MP0602 meeting, Brno Influence of pH x2400 x % Ag 3.8% Ag

TT COST MP0602 meeting, Brno Flip-chip Bonding Components Bumps are pure tin from a neutral electrolyte!

TT COST MP0602 meeting, Brno Hot-stage Microscope 1. Vacuum system 2. Heating chamber (6x8x6 mm) 3. Imaging system

TT COST MP0602 meeting, Brno Forming and Remelting c)d) AuSnNi

TT COST MP0602 meeting, Brno Cross-section (LOM) mg of Au and Sn powder – a slightly hypoeutectic composition of 83.1% Au and 16.9% Sn (wt.%)

TT COST MP0602 meeting, Brno AuSn Phase Diagram Au 5 Sn AuSn Au 2 Sn Sample composition

TT COST MP0602 meeting, Brno Cross-section (SEM) Au 5 S n Au80Sn20 (eut.)