Minimizing Voiding. Cristian Tudor Applications Engineer Eastern Europe

Transcription

1 Minimizing Voiding Cristian Tudor Applications Engineer Eastern Europe INDIUM CORPORATION 1

2 Indium Corporation s Business We develop, manufacture, market and support solders, electronics assembly and packaging materials, specialty alloys, alternative energy materials, PVD Targets and inorganic compounds. INDIUM CORPORATION 2

3 Indium Corporation - Overview Privately held business / Family-owned Founded in 1934 > 800 Employees > 5% of revenue invested in R&D 11 Manufacturing Facilities Worldwide INDIUM CORPORATION 3

4 Our Goal Increase our customers productivity and profitability through premium design, application, and service using advanced materials. Our basis for success: Excellent product quality and performance Technical and customer service Cutting-edge materials research and development Extensive product range Lowest cost of ownership INDIUM CORPORATION 4

5 Indium Corporation: Manufacturing and Sales Offices INDIUM CORPORATION 5

6 Verticals Served Automotive Defence Downhole Power Modules Laser/Fibre Optic LED Medical MEMs Metal Refining and Reclaim PCBA RF/Microwave Thermal INDIUM CORPORATION 6

7 Indium s Market Share of Solder Paste Worldwide Market Share: about 10-12% Americas Market Share: about 22-25% Indium Corporation has been the fastest growing premium solder paste supplier during the past two years. Indium is the preferred development partner and supplier for several, industry-leading, western and Asian OEM s INDIUM CORPORATION 7

8 Alignment with Industry Organisations IEEE Dr Ning-Cheng Lee: Exceptional Technical Achievement Award (2006) Electronics Manufacturing Technology Award (2010) Technical Advisory board CPMT SMTA : Greg Evans: Former SMTA President Founder s Award (2005) Dr Ning-Cheng Lee: Member of Distinction (2002) Dr Andy Mackie: Technical advisory board IWLPC show (2010) IMAPS Dr Andy Mackie: imaps Automotive session chair (2010) SEMI Dr Andy Mackie: Standards development inemi Dr Andy Mackie: Chair DOE/SSL Roadmap Packaging Subgroup (2010) IPC Dr Andy Mackie: President s award (2001) Past Vice-Chair Assembly Materials Standards Development Committee INDIUM CORPORATION 8

9 Void requirements - VW < 10% on all components - HKMC < 15% on all components - Ford < 20% on all components - Daimler< 20% on all components INDIUM CORPORATION 9

10 Void Specs IPC 610F Inspection Criteria - BGA < 30% of any ball in X- Ray image area - Through hole joints < 25% of solder joint area INDIUM CORPORATION 10

11 Why the fuss on voids? Longer cycles -40/+125C, 1000 cycles cycles Higher Service Temp 125 deg C 150 & 175 deg C More Dewing cycles Higher Mechanical Shock Resistance INDIUM CORPORATION 11

12 Effect of Voids Mechanical Thermal INDIUM CORPORATION 12

13 Void Types INDIUM CORPORATION 13

14 Voiding Ishikawa Diagram INDIUM CORPORATION 14

15 Solder Paste INDIUM CORPORATION 15

16 No Clean Flux Technology Activators - cleaning agent during reflow, Dissolves oxides off metal surfaces & promotes wetting Gelling Agents thickeners, Regulate viscosity and paste stability - rheological additives Rosin- Tacky and viscous, acts as an oxygen barrier Solvents - dissolve chemicals, activators, gelling agents, & resins to create a homogeneous paste INDIUM CORPORATION 16

17 Flux Engineering for Reduced Voids - Overall void% - Void size - Void position INDIUM CORPORATION 17

18 1. Effect of Temperature on QFN Voiding QFN: Large 7.75mm Square Ground Plane Stencil: 125u thick; Laser Cut stainless steel Printer Settings: (MPM) Squeegee Speed: 75mm/s Squeegee Pressure: ~12Kg Squeegee Length: 300mm Separation Speed: 5mm/s Separation Distance: 2mm 2 Reflow Profiles (peak of C & C) Pastes Indium8.9HF Paste Y 3 Panels 3 Boards Per Panel 4 QFNs Per Board Total of 36 QFNs per Profile per Paste INDIUM CORPORATION 18

19 1. Effect of Temperature on QFN Voiding P5 Hot Profile INDIUM CORPORATION 19

20 1. Effect of Temperature on QFN Voiding Void% vs Peak Temp Indium8.9HF Paste Y 7.3% 11.6% 34.1% 22.7% C peak C peak C peak C peak INDIUM CORPORATION 20

21 2. Voiding (BGA, 0402, SOIC) Cold Profile Hot Profile Peak Temp = deg C Profile time = 4 min Peak Temp = deg C Profile time = 6.5 min INDIUM CORPORATION 21

22 2. Voiding (BGA, 0402, SOIC) Voiding < 10% Effect of - Metal load - Air vs Nitrogen - Cold vs Hot profiles INDIUM CORPORATION 22

23 3. DPAK Voiding Indium8.9HF Paste Y Indium8.9HF Paste Y - Different stencil apertures - Different via design - Air vs N2 INDIUM CORPORATION 23

24 Data 4. Effect of Stencil Thickness 18 Interval Plot of Void % 4 mil Stencil, Void % 5 Mil Stencil 95% CI for the Mean u stencil Void % 4 mil Stencil 125u stencil Void % 5 Mil Stencil Individual standard deviations are used to calculate the intervals. INDIUM CORPORATION 24

25 5. Via in Pad Voiding - CSP INDIUM CORPORATION 25

26 6. Effect of Intermetallics INDIUM CORPORATION 26

27 7. Reflow Profile Variables & Voiding In general, on the reflow profile If the preheat is too quick - More voiding not enough time for flux volatiles to escape before solder becomes molten there can be excessive slump thus reducing the standoff and prevent escape of flux volatiles- More voiding A very short reflow profile can more easily trap flux volatiles- More voiding Excessive peaks or long profiles can cause more oxidation- More voiding INDIUM CORPORATION 27

28 8. QFN Voiding PCB Pad Designs INDIUM CORPORATION 28

29 8. QFN Voiding PCB Pad Designs Profiles Used INDIUM CORPORATION 29

30 8. QFN Voiding PCB Pad Designs Reflow Profile Effect INDIUM CORPORATION 30

31 8. QFN Voiding PCB Pad Designs Venting Effect INDIUM CORPORATION 31

32 8. QFN Voiding PCB Pad Designs. SMD vs NSMD Thermal Pad Effect INDIUM CORPORATION 32

33 8. QFN Voiding PCB Pad Designs Venting reduces the size of voids & total void area For thermal transfer, large voids are more disruptive -> smaller voids allow for more transfer Solder mask defined pads offer further improvement INDIUM CORPORATION 33

34 9. Flux Coated Preforms for Lower QFN Voiding Flux-Coated preform Less Flux = Less Voiding Flux Coated Preform Placed preform must be as flat as possible after being placed into the paste Placement force is critical Placement pressure should be increased more than normal levels to insure that the component forms good contact with paste perimeter around the preform Nozzle should be large enough to occupy as much of the surface as possible INDIUM CORPORATION 34

35 10. Vacuum Soldering for Lower QFN Voiding Low Voiding no problem What about solder splash, long TAL, IMC? INDIUM CORPORATION 35

36 Indium8.9HF Solder Paste Halogen-Free, Pb-Free, No-Clean Solder Paste High Transfer Efficiency with Low Variability Outstanding broadband print transfer Excellent Response to pause performance Unique Resilient Oxidation Barrier Technology Elimination of HiP defects Eliminates graping phenomenon Robust Reflow Capability Wide Processing window accommodates various board sizes, throughput requirements, and minimizes potential defects. Low voiding (<5%) with a vast array of thermal profiles 12 months refrigerated shelf life (< 10C) 30 days shelf life at room temperature (< 25C) Stencil life: up to 60 hours (at 30-60%RH and 22C-28C) INDIUM CORPORATION 36

37 Indium8.9HF Solder Paste Excellent Pin in Paste Solderability and Hole Fill Superb Slump Resistance Clear, Restricted, Encapsulating Flux Residue with High Reliability INDIUM CORPORATION 37

38 Thank you! INDIUM CORPORATION 38