welcome to the world of lead free hot air leveling · operating temp.(0c) ... electrolytic...

Welcome to the Real World of Lead Free

SolderingMetallic Resources, Inc.Metallic Resources, Inc.

Howard StevensHoward StevensNimalNimal LiyanageLiyanage, Ph.D, Ph.D

Metallic Resources, Inc.

Objective: to Provide Education Objective: to Provide Education Regarding the Effects of Various Regarding the Effects of Various Lead Free Soldering Alloys used in Lead Free Soldering Alloys used in Assembly Operations on Available Assembly Operations on Available Board Finishes used in PC Board Board Finishes used in PC Board Fabrication.Fabrication.


Prime Importance to Circuit Board Prime Importance to Circuit Board Fabricators:Fabricators:

Board Finish Selection.Board Finish Selection.Cost.Cost.Shelf Life.Shelf Life.Process Changes and Parameters.Process Changes and Parameters.Demonstrated Demonstrated SolderabilitySolderability..


Prime Importance to Circuit Board Prime Importance to Circuit Board Assemblers:Assemblers:

Alloy Selection.Alloy Selection.Cost.Cost.Wetting and Wicking Capability.Wetting and Wicking Capability.Process Changes and Parameters.Process Changes and Parameters.Demonstrated Demonstrated SolderabilitySolderability..


Primary Board Finish Purpose:Primary Board Finish Purpose:To prevent Oxidation of the Copper To prevent Oxidation of the Copper Traces, Pads, and Through Holes, Traces, Pads, and Through Holes, in Order to Preserve in Order to Preserve SolderabilitySolderability..


When Coating Bare BoardsWhen Coating Bare Boards……Different Finishes Lose Different Finishes Lose SolderabilitySolderability at Different Rates.at Different Rates.SolderabilitySolderability will Deteriorate Over will Deteriorate Over Time.Time.Longer Storage Time Equals Less Longer Storage Time Equals Less SolderabilitySolderability..


Available Board Finishes:Available Board Finishes:Lead Free HAL.Lead Free HAL.Immersion Tin.Immersion Tin.Immersion Silver.Immersion Silver.ENIG.ENIG.OSP.OSP.


Immersion Tin:Immersion Tin:Process Dependent with Relatively High Process Dependent with Relatively High Cost.Cost.66--12 month Shelf Life?12 month Shelf Life?Thickness limited to less than 1 micron Thickness limited to less than 1 micron (Average of 0.75(Average of 0.75--1.2 microns).1.2 microns).Loss of Loss of SolderabilitySolderability when Forming when Forming IntermetallicsIntermetallics with Copper. with Copper.


Immersion Silver:Immersion Silver:Process Dependent with Relatively High Process Dependent with Relatively High Cost.Cost.66--12 month Shelf Life?12 month Shelf Life?Thickness limited to less than 1 micron Thickness limited to less than 1 micron (Average of 0.2(Average of 0.2--0.3 microns).0.3 microns).Loss of Loss of SolderabilitySolderability when Silver has when Silver has Diffused into the copper.Diffused into the copper.Potential for Tarnishing.Potential for Tarnishing.


ENIG (ENIG (ElectrolessElectroless Nickel Immersion Gold):Nickel Immersion Gold):Higher Cost.Higher Cost.Thickness limited to less than 1 micron Thickness limited to less than 1 micron (Average of 0.05(Average of 0.05--0.09 microns). 0.09 microns). More Difficult to Solder to. Introduces More Difficult to Solder to. Introduces Gold into the Solder Pot which may Gold into the Solder Pot which may Cause a more Brittle Solder Joint.Cause a more Brittle Solder Joint.Process can go Awry more Often than Process can go Awry more Often than HAL, requiring replacement of HAL, requiring replacement of Chemicals.Chemicals.


OSP (Organic Solder Preservative):OSP (Organic Solder Preservative):Limited Shelf Life.Limited Shelf Life.Works better with High Activity Works better with High Activity Fluxes.Fluxes.Temperature Dependent.Temperature Dependent.Thickness limited to less than 1 Thickness limited to less than 1 micron (Average of 0.2micron (Average of 0.2--0.3 0.3 microns).microns).


Hot Air Leveling:Hot Air Leveling:The most Cost Effective.The most Cost Effective.Yields the Best Yields the Best SolderabilitySolderability of the of the PCB.PCB.Yields an Excellent, Long Shelf Life Yields an Excellent, Long Shelf Life (1 to 1.5 years) no Different than (1 to 1.5 years) no Different than Sn63/Pb37.Sn63/Pb37.


Hot Air Leveling:Hot Air Leveling:Compatible with Wave Soldering, Compatible with Wave Soldering, SMT, Selective Soldering.SMT, Selective Soldering.Existing Equipment Historically Existing Equipment Historically Geared to Hot Air Leveling.Geared to Hot Air Leveling.SolderabilitySolderability Confirmed by Visual Confirmed by Visual Inspection.Inspection.


Many Lead Free Alloys Considered Many Lead Free Alloys Considered for Board Fabrication, Wave, SMT, for Board Fabrication, Wave, SMT, and Selective Soldering.and Selective Soldering.


Some Guidelines in Alloy Choice:Some Guidelines in Alloy Choice:Melting Point was not as Important Melting Point was not as Important as was First Thought.as was First Thought.Adjust the Process to Compensate Adjust the Process to Compensate (somewhat Higher Solder Pot (somewhat Higher Solder Pot Temperatures will be Necessary).Temperatures will be Necessary).


Alloy Choices for Fabrication and Alloy Choices for Fabrication and Assembly:Assembly:

Antimony (Antimony (SbSb) and Bismuth (Bi) ) and Bismuth (Bi) Eliminated due to Brittle Solder Eliminated due to Brittle Solder Joints and Finishes.Joints and Finishes.Adding Zinc (Zn) Creates a Dull, Adding Zinc (Zn) Creates a Dull, Elastic Finish, which LeavesElastic Finish, which Leaves……


Alloy Choices for Fabrication and Alloy Choices for Fabrication and Assembly:Assembly:

Sn96.5/Ag3.0/Cu0.5 (SAC Alloys)Sn96.5/Ag3.0/Cu0.5 (SAC Alloys)Sn99.3/Cu0.7 EutecticSn99.3/Cu0.7 EutecticSn99.5/Cu0.5/Ni0.5Sn99.5/Cu0.5/Ni0.5Sn99.5/Cu0.5/CoSn99.5/Cu0.5/Co


A Binary Alloy is Preferable to a A Binary Alloy is Preferable to a Tertiary Alloy Because it is: Tertiary Alloy Because it is:

Easier to Keep the Solder in Spec Easier to Keep the Solder in Spec for Both PC Fabrication and PC for Both PC Fabrication and PC Assembly Operations.Assembly Operations.Lower in Cost. Lower in Cost.


SAC Alloys:SAC Alloys:Advantages: Readily Accepted by Advantages: Readily Accepted by Industry, Lower Melt Point Compared to Industry, Lower Melt Point Compared to SnSn/Cu Alloys./Cu Alloys.Disadvantages: Higher Cost, Limited Disadvantages: Higher Cost, Limited Longevity Studies, Dull Crystalline and Longevity Studies, Dull Crystalline and Grainy Solder Joint, Higher Melt Temp., Grainy Solder Joint, Higher Melt Temp., Poorer ThroughPoorer Through--Hole Fill, Potential for Hole Fill, Potential for Stainless Steel Corrosion, Poor Stainless Steel Corrosion, Poor Coplanar Surfaces in HAL, Tertiary Coplanar Surfaces in HAL, Tertiary Alloy.Alloy.


Sn99.3/Cu0.7 Eutectic:Sn99.3/Cu0.7 Eutectic:Advantages: Lower in Cost, Binary Advantages: Lower in Cost, Binary Alloy.Alloy.Disadvantages: Higher Melt Point Disadvantages: Higher Melt Point (228(228°°C Compared to 183 C Compared to 183 °°C for C for Sn63), Duller Crystalline Finish, No Sn63), Duller Crystalline Finish, No Longevity Studies, Corrosion in Longevity Studies, Corrosion in Stainless Steel Solder Pot?Stainless Steel Solder Pot?


Sn99.5/Cu0.5/Ni0.05:Sn99.5/Cu0.5/Ni0.05:Advantages: Brighter, Shinier Board Advantages: Brighter, Shinier Board Finish and Smoother, more Flat Surface.Finish and Smoother, more Flat Surface.Disadvantages: Higher Melt Point Disadvantages: Higher Melt Point (228(228°°C Compared to 183 C Compared to 183 °°C for Sn63), C for Sn63), Limited Longevity Studies, Corrosion in Limited Longevity Studies, Corrosion in Stainless Steel Solder Pot? Patented Stainless Steel Solder Pot? Patented Alloy Results in Higher Cost.Alloy Results in Higher Cost.


Sn99.5/Cu0.5/CoSn99.5/Cu0.5/Co::Advantages: Lower Cost. Smoother, Advantages: Lower Cost. Smoother, Uniform Flat Surface. Brighter, Shinier Uniform Flat Surface. Brighter, Shinier Board Finish and Solder Joint, no Joint Board Finish and Solder Joint, no Joint Cracking or Solder Voids, Binary Alloy.Cracking or Solder Voids, Binary Alloy.Disadvantages: Higher Melt Point Disadvantages: Higher Melt Point (228(228°°C Compared to 183 C Compared to 183 °°C for Sn63, C for Sn63, 217 217 °°C Compared to SAC305), Limited C Compared to SAC305), Limited Longevity Studies, Corrosion in Longevity Studies, Corrosion in Stainless Steel Solder Pot? Stainless Steel Solder Pot?


Sn99.5/Cu0.5/CoSn99.5/Cu0.5/Co::The Addition of Grain Refining The Addition of Grain Refining Trace Elements such as Trace Elements such as Germanium, Nickel, Silver and Germanium, Nickel, Silver and Cobalt will Overcome Many Cobalt will Overcome Many Disadvantages of Disadvantages of SnSn/Cu and SAC /Cu and SAC Alloys.Alloys.


Sn63/Pb37 Bottom Side Fill:Sn63/Pb37 Bottom Side Fill:


Sn99.5/Cu0.5/Co Bottom Side FillSn99.5/Cu0.5/Co Bottom Side Fill::


Sn99.5/Cu0.5/Co Top Side Fill:Sn99.5/Cu0.5/Co Top Side Fill:


Testing of Various Alloys.Testing of Various Alloys.Physical Properties:Physical Properties:

SAC305SAC305 SnSn/Cu/Co/Cu/Co 63/3763/37

Melting Point (Melting Point (00C) 217 227 183 C) 217 227 183 Density (g/cmDensity (g/cm33) 7.4 7.3 8.) 7.4 7.3 8.44Operating temp.(Operating temp.(00C) 250C) 250--260 265 260 265 -- 275 245275 245--260260Tensile Strength (M Pa) 52 28 Tensile Strength (M Pa) 52 28 3131Elongation 27 Elongation 27 27 3527 35


Testing of Various Alloys.Testing of Various Alloys.Physical Properties:Physical Properties:

SAC305SAC305 SnSn/Cu/Co/Cu/Co 63/3763/37Thermal ConductivityThermal Conductivity(J/m(J/m••s s ••K)K) 64 64 64 64 50 50 Electrical Resistance Electrical Resistance ((µµΏΏmm) 0.15 0.13) 0.15 0.13 0.170.17Thermal Shock Thermal Shock ((--40/+80 40/+80 00C Each 1 Hr) C Each 1 Hr) ››1000 Cycles 1000 Cycles ››1000 Cycles 500 Cycles1000 Cycles 500 Cycles


General Wetting Characteristics:General Wetting Characteristics:


Testing of Sn63 @ 250Testing of Sn63 @ 250°°CC: Wetting: Wetting


Testing of Sn99.5/Cu0.5/CoTesting of Sn99.5/Cu0.5/Co: Wetting: Wetting


Comparison of WB Tests:Comparison of WB Tests:Sn63/Pb37Sn63/Pb37 SnSn/Cu/Co /Cu/Co

Alloy Temp. Alloy Temp. 00C 250 265C 250 265Max Wetting Force 0.32 >0.31Max Wetting Force 0.32 >0.31((mNmN/mm) /mm) Time to achieve max Time to achieve max wetting Force (sec) 0.241 0.24wetting Force (sec) 0.241 0.24Av. force at 1.125 sec. 0.32 0.31Av. force at 1.125 sec. 0.32 0.31


Wetting ComparisonWetting Comparison::For the Sn63 solder, wetting was For the Sn63 solder, wetting was instaninstan--taneoustaneous, rising to maximum wetting force in , rising to maximum wetting force in 0.241 seconds. Maximum wetting force was 0.241 seconds. Maximum wetting force was 0.32mN.mm of 0.32mN.mm of wettablewettable length.length.For the Sn99.5/Cu0.5/Co at 265 and 275For the Sn99.5/Cu0.5/Co at 265 and 275°°C, C, the wetting was also instantaneous. The rate the wetting was also instantaneous. The rate of rise is uniform, near textbook, and the of rise is uniform, near textbook, and the maximum wetting force is very slightly lower maximum wetting force is very slightly lower at 0.31mN/mm.at 0.31mN/mm.


Spread ComparisonSpread Comparison: Sn63/Pb37: Sn63/Pb37


Spread ComparisonSpread Comparison: SAC305: SAC305


Spread ComparisonSpread Comparison: : SnSn/Cu/Co/Cu/Co


Spread ComparisonSpread Comparison::


Wetting/Spread Test Results:Wetting/Spread Test Results:ENIG Showed Poor Wetting. Sn63 ENIG Showed Poor Wetting. Sn63 gave 20% more Spread than gave 20% more Spread than SAC305 and SAC305 and SnSn/Cu/Co Pastes./Cu/Co Pastes.Immersion Silver Showed Poor Immersion Silver Showed Poor Wetting with all Pastes.Wetting with all Pastes.


Wetting/Spread Test Results:Wetting/Spread Test Results:OSP Showed Poor Wetting with OSP Showed Poor Wetting with SnSn/Cu/Co and SAC Alloys. Sn63/Pb37 /Cu/Co and SAC Alloys. Sn63/Pb37 was 30% Better in Wetting and Spread.was 30% Better in Wetting and Spread.Immersion Tin Showed Total Diffusion Immersion Tin Showed Total Diffusion of Sn63 through the Tin Coating onto of Sn63 through the Tin Coating onto Underlying Copper. Also Evidence of Underlying Copper. Also Evidence of IntermetallicsIntermetallics at the Outer Edges of the at the Outer Edges of the Spread.Spread.


Wetting/Spread Test Conclusions:Wetting/Spread Test Conclusions:HAL Provided the Best Overall HAL Provided the Best Overall Wetting no Matter what Paste was Wetting no Matter what Paste was Used.Used.The The SnSn/Cu/Co Alloy Wets as Well /Cu/Co Alloy Wets as Well as the SAC305 Alloy, therefore the as the SAC305 Alloy, therefore the Low Cost of Low Cost of SnSn/Cu/Co becomes /Cu/Co becomes Much More Important.Much More Important.


Wetting/Spread Test Conclusions:Wetting/Spread Test Conclusions:Immersion Silver Exhibited the Immersion Silver Exhibited the Poorest Wetting and Spread Poorest Wetting and Spread Across the Board.Across the Board.ENIG and OSP were a Little Better ENIG and OSP were a Little Better with Sn63/Pb37 Pastes.with Sn63/Pb37 Pastes.


Average Comparative Spread of All Average Comparative Spread of All Alloys:Alloys:

8 7.2 %

8 2 .5%8 3 .8 %

8 9 .6 %

9 5.5%

75.0%

80.0%

85.0%

90.0%

95.0%

100.0%

Spread

Performance

ENIGImAgOSPImSnHAL


Average Spread of Water Soluble Average Spread of Water Soluble SAC305 vs. SAC305 vs. SnSn/Cu/Co:/Cu/Co:

0 . 0 %

10 . 0 %

2 0 . 0 %

3 0 . 0 %

4 0 . 0 %

5 0 . 0 %

6 0 . 0 %

7 0 . 0 %

8 0 . 0 %

9 0 . 0 %

10 0 . 0 %

Spread

Performance

SAC305WSCobalt995WS


Average Spread of No Clean SAC305 Average Spread of No Clean SAC305 vs. vs. SnSn/Cu/Co:/Cu/Co:

0.0%10.0%20.0%30.0%40.0%50.0%60.0%70.0%80.0%90.0%

100.0%

Spread

Performance

SA C 3 0 5N C

C obalt 9 9 5N C


Results of SAC305 vs. Results of SAC305 vs. SnSn/Cu/Co /Cu/Co Comparison:Comparison:

No Significant Differences in No Significant Differences in Wetting or Spread Between the Wetting or Spread Between the Two Alloys.Two Alloys.


Testing of Sn99.5/Cu0.5/CoTesting of Sn99.5/Cu0.5/Co::Copper Thickness Reduction:Copper Thickness Reduction:

Number ofPasses

Copper Thickness (Avg.) mils Variation From Original Copper Thickness (mils)

Sn99.7Cu0.3/Co Sn63 Sn99.7Cu0.3/Co Sn63

0 0.8 1 0 01 0.8 0.9 0.0 0.12 0.7 0.9 0.1 0.13 0.6 0.8 0.2 0.24 0.5 0.8 0.3 0.25 0.4 0.7 0.4 0.36 0.2 0.6 0.6 0.4


CoCo--Planarity Testing:Planarity Testing:Sn63/37 PanelsSn63/37 Panels SnSn/Cu/Co /Cu/Co

PanelsPanelsPanels Measured 44 Panels Measured 44 4444Mean 169.6 Mean 169.6 µµ--in. 166.7 in. 166.7 µµ--in.in.Standard Deviation 65.6 Standard Deviation 65.6 µµ--in. 49.1 in. 49.1 µµ--in.in.Minimum 109.0 Minimum 109.0 µµ--in. 102.0 in. 102.0 µµ--in.in.Maximum 486.7 Maximum 486.7 µµ--in. 270.2 in. 270.2 µµ--in.in.Range 377.7 Range 377.7 µµ--in. 168.2 in. 168.2 µµ--inin


Sn99.5/Cu0.5/Co. Sn99.5/Cu0.5/Co. The Addition of Cobalt Makes for a The Addition of Cobalt Makes for a Brighter, Shinier, less Grainy Brighter, Shinier, less Grainy Solder Finish and Joint with no Solder Finish and Joint with no Joint Cracking or Solder Voids Joint Cracking or Solder Voids Compared to Compared to SnSn/Cu or SAC305./Cu or SAC305.


Sn99.5/Cu0.5/Co. Sn99.5/Cu0.5/Co. Electrolytic Processing with Lower Electrolytic Processing with Lower Viscosity and Surface Tension Provides Viscosity and Surface Tension Provides Improved Fluidity, and Greater Wetting Improved Fluidity, and Greater Wetting and Wicking Capability for the Best and Wicking Capability for the Best ThroughThrough--Hole Fill.Hole Fill.Electrolytic Processing Reduces ReElectrolytic Processing Reduces Re--Work (Bridging, Flagging, Work (Bridging, Flagging, CobwebbingCobwebbing, , IciclingIcicling, Solder Voids) at Least 30% and , Solder Voids) at Least 30% and Joint Cracking Compared to All Other Joint Cracking Compared to All Other Lead Free Alloys!Lead Free Alloys!


Cost of Sn99.5/Cu0.5/Co: Cost of Sn99.5/Cu0.5/Co: Little Difference Compared to Little Difference Compared to SnSn/Cu./Cu.Significantly Less Expensive than Significantly Less Expensive than SAC305 for Assembly Operations. SAC305 for Assembly Operations. Less Expensive Compared to Other Less Expensive Compared to Other Available Board Finishes due to no Available Board Finishes due to no Additional Processes Involved.Additional Processes Involved.


Summary: Summary: Many Board Finishes are Available and Many Board Finishes are Available and Each Works Differently for PC Each Works Differently for PC Fabrication. Hot Air Leveling Provides Fabrication. Hot Air Leveling Provides More Advantages than Other Board More Advantages than Other Board Finishes.Finishes.Many Lead Free Alloys are Available for Many Lead Free Alloys are Available for PC Assembly. A Binary Alloy has PC Assembly. A Binary Alloy has Advantages over a Tertiary Alloy for Advantages over a Tertiary Alloy for Wave Soldering.Wave Soldering.


Summary: An Summary: An SnSn/Cu/Co Alloy/Cu/Co Alloy……Provides the Greatest Cost Provides the Greatest Cost Effectiveness for both PC Effectiveness for both PC Fabrication and Assembly Fabrication and Assembly Operations.Operations.Provides Excellent Provides Excellent SolderabilitySolderability. . Thoroughly Independently Tested.Thoroughly Independently Tested.


Summary: An Summary: An SnSn/Cu/Co Alloy/Cu/Co Alloy……Provides a more Uniform Coating Provides a more Uniform Coating and Smoother Surface in HAL and and Smoother Surface in HAL and the Brightest, Shiniest Solder the Brightest, Shiniest Solder Joints with No Grain or Voids Joints with No Grain or Voids compared to all other lead free compared to all other lead free alloys in all Assembly Operations.alloys in all Assembly Operations.


Benefits of Partnering with Metallic Benefits of Partnering with Metallic Resources:Resources:

Unlimited Free Pot Analysis. For Unlimited Free Pot Analysis. For Lead Free, One Analysis each Lead Free, One Analysis each Week is Recommended to Monitor Week is Recommended to Monitor Copper and Other Contaminant Copper and Other Contaminant Levels. Levels.



Uninterrupted Supply of Product Uninterrupted Supply of Product Guaranteed. Product is Stocked All Guaranteed. Product is Stocked All Over the USA. In Case of any Over the USA. In Case of any Catastrophe, Dual Manufacturing Catastrophe, Dual Manufacturing Locations Assure No Loss of Locations Assure No Loss of Production.Production.



Complete Recycling Services.Complete Recycling Services.Customer Audits and Tours Available at Customer Audits and Tours Available at Your Request to See our Manufacturing Your Request to See our Manufacturing Process in Person. (Bose, Harman Process in Person. (Bose, Harman Becker, Honeywell, Rockwell, etc.)Becker, Honeywell, Rockwell, etc.)


Thank You for Your Interest! Thank You for Your Interest! Metallic Resources Hopes Metallic Resources Hopes You Now Have More You Now Have More Information to Help Make the Information to Help Make the Critical Choices You Face.Critical Choices You Face.

welcome to the world of lead free hot air leveling · operating temp.(0c) ... electrolytic...

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