Minimizing Voiding - Amtest 2017 - Void-free lemljenje... · © INDIUM CORPORATION Minimizing Voiding Cristian Tudor Applications Engineer – Eastern Europe [email protected] 9/25/2017

© INDIUM CORPORATION © INDIUM CORPORATION

Minimizing

Voiding Cristian Tudor

Applications Engineer – Eastern

Europe

[email protected]

1 9/25/2017

mailto:[email protected]

© INDIUM CORPORATION 2 9/25/2017

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 - Overview

• Privately held business / Family-owned

• Founded in 1934 > 800 Employees

• > 5% of revenue invested in R&D

• 11 Manufacturing Facilities Worldwide


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:

Manufacturing and Sales Offices


Verticals Served

Metal Refining and Reclaim

Automotive Defence Downhole Power Modules

Laser/Fibre Optic LED Medical MEMs

PCBA RF/Microwave Thermal


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


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

http://www.smta.org/index.cfm

http://www.imaps.org/imaps2009/index.htm

http://www.ieee.org/index.html?WT.mc_id=hpf_logo


Void requirements

- VW < 10% on all components

- HKMC < 15% on all components

- Ford < 20% on all components

- Daimler< 20% on all components


Void Specs

IPC 610F Inspection Criteria

- BGA < 30% of any ball in X-Ray image area

- Through hole joints < 25% of solder joint area


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


Effect of Voids

Mechanical Thermal


Void Types


Voiding – Ishikawa Diagram


Solder Paste


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


Flux Engineering for Reduced

Voids

- Overall void%

- Void size

- Void position


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



Voiding

P5 Hot Profile



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


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


2. Voiding (BGA, 0402, SOIC)

Voiding < 10%

Effect of

- Metal load

- Air vs Nitrogen

- Cold vs Hot

profiles


3. DPAK Voiding

Indium8.9HF Paste Y Indium8.9HF Paste Y

- Different stencil apertures

- Different via design

- Air vs N2


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


5. Via in Pad Voiding - CSP


6. Effect of Intermetallics


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


8. QFN Voiding – PCB Pad

Designs



Designs Profiles Used



Designs Reflow Profile Effect



Designs Venting Effect


8. QFN Voiding – PCB Pad Designs.

SMD vs NSMD Thermal Pad Effect



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


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


10. Vacuum Soldering for Lower

QFN Voiding

Low Voiding no problem What about solder splash, long TAL, IMC…?


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)


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

Thank you!

38 9/25/2017

Documents

Minimizing Voiding - Amtest 2017 - Void-free lemljenje... · © INDIUM CORPORATION Minimizing Voiding Cristian Tudor Applications Engineer – Eastern Europe [email protected] 9/25/2017