Minimizing Voiding - Amtest 2017 - Void-free lemljenje... · © INDIUM CORPORATION Minimizing...
Transcript of Minimizing Voiding - Amtest 2017 - Void-free lemljenje... · © INDIUM CORPORATION Minimizing...
© INDIUM CORPORATION © INDIUM CORPORATION
Minimizing
Voiding Cristian Tudor
Applications Engineer – Eastern
Europe
1 9/25/2017
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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.
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Indium Corporation - Overview
• Privately held business / Family-owned
• Founded in 1934 > 800 Employees
• > 5% of revenue invested in R&D
• 11 Manufacturing Facilities Worldwide
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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
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Indium Corporation:
Manufacturing and Sales Offices
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Verticals Served
Metal Refining and Reclaim
Automotive Defence Downhole Power Modules
Laser/Fibre Optic LED Medical MEMs
PCBA RF/Microwave Thermal
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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
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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
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Void requirements
- VW < 10% on all components
- HKMC < 15% on all components
- Ford < 20% on all components
- Daimler< 20% on all components
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Void Specs
IPC 610F Inspection Criteria
- BGA < 30% of any ball in X-Ray image area
- Through hole joints < 25% of solder joint area
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Why the fuss on voids?
• Longer cycles
-40/+125C, 1000 cycles
3000-5000 cycles
• Higher Service Temp
125 deg C 150 & 175 deg C
• More Dewing cycles
• Higher Mechanical Shock Resistance
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Effect of Voids
Mechanical Thermal
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Void Types
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Voiding – Ishikawa Diagram
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Solder Paste
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No Clean Flux Technology
Activators - cleaning agent during reflow, Dissolves oxides off metal surfaces & promotes wetting
Rosin- Tacky and viscous, acts as an oxygen barrier
Gelling Agents – thickeners, Regulate viscosity and paste stability - rheological additives
Solvents - dissolve chemicals, activators, gelling agents, & resins to create a homogeneous paste
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Flux Engineering for Reduced
Voids
- Overall void%
- Void size
- Void position
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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 235-240C & 250-255C)
• Pastes
– Indium8.9HF
– Paste Y
• 3 Panels
• 3 Boards Per Panel
• 4 QFNs Per Board
• Total of 36 QFNs per Profile per Paste
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1. Effect of Temperature on QFN
Voiding
P5 Hot Profile
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1. Effect of Temperature on QFN
Voiding – Void% vs Peak Temp
250-255C peak
235-240C peak
Paste Y
250-255C peak
235-240C peak
7.3% 11.6%
22.7%
34.1%
Indium8.9HF
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2. Voiding (BGA, 0402, SOIC)
Cold Profile Hot Profile
Peak Temp = 235-240 deg C
Profile time = 4 min
Peak Temp = 250-255 deg C
Profile time = 6.5 min
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2. Voiding (BGA, 0402, SOIC)
Voiding < 10%
Effect of
- Metal load
- Air vs Nitrogen
- Cold vs Hot
profiles
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3. DPAK Voiding
Indium8.9HF Paste Y Indium8.9HF Paste Y
- Different stencil apertures
- Different via design
- Air vs N2
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4. Effect of Stencil Thickness
Void % 5 Mil StencilVoid % 4 mil Stencil
18
17
16
15
14
13
12
Data
Interval Plot of Void % 4 mil Stencil, Void % 5 Mil Stencil95% CI for the Mean
Individual standard deviations are used to calculate the intervals.
100u stencil 125u stencil
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5. Via in Pad Voiding - CSP
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6. Effect of Intermetallics
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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
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8. QFN Voiding – PCB Pad
Designs
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8. QFN Voiding – PCB Pad
Designs Profiles Used
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8. QFN Voiding – PCB Pad
Designs Reflow Profile Effect
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8. QFN Voiding – PCB Pad
Designs Venting Effect
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8. QFN Voiding – PCB Pad Designs.
SMD vs NSMD Thermal Pad Effect
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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
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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
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10. Vacuum Soldering for Lower
QFN Voiding
Low Voiding no problem What about solder splash, long TAL, IMC…?
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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)
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Indium8.9HF Solder Paste
• Excellent Pin in Paste Solderability and Hole Fill
• Superb Slump Resistance
• Clear, Restricted, Encapsulating Flux Residue with High
Reliability
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Thank you!
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