Bleifreie Bauelemente und Bauelemente oberflächen

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1 Bleifreie Bauelemente und Bauelemente oberflächen E4 Presentation Infineon Technologies /ST Microelectronics/ Philips Semiconductors/ Freescale Semiconductor Dr.ir. Pascal Oberndorff 8. Europäisches Elektroniktechnologie Kolleg März 2004

2 RoHS compliance, green package The E4 classifies a product as green when it is compliant to RoHS: free* from the substances Pb, Hg, Cd, Cr6+,PBB and PBDE * Max. concentration limits to be respected. The actual packages do NOT contain Hg,Cd,Cr6+,PBB and PBDE! Therefore the elimination of Pb will result in the package classification green. It may be remarked that the presence of exempted Pb does not affect the classification green (e.g. Pb based die-attach alloys). The definition of green is subjected to be updated within some years. Halogen free materials might become a part of the new definition, Although a part of the packages is already halogen free, the industrial availability of this type of materials is still limited and and full implementation might take some years.

3 Target / Status Pb-free Programs in the Industry Two Targets: Compatibility with both SnPb and Pb-free board soldering (with extended temperature range) Elimination of Pb in package terminals (leads, balls, bumps) Status Main Japanese consumer market converted to lead-free soldering Major conversion to lead free components by 1H05

4 Standardisation IPC/JEDEC J-STD-020C IPC/JEDEC published an updated spec per July 2004 : J-Std-020C Main changes compared to J-Std-020B : 9 categories (3x thickness, 3x volume ) in stead of 4 today : Package Thickness Volume < 350 mm 3 Volume mm 3 Volume > 2000 mm 3 <1.6 mm mm mm > 2.5 mm C, 250 C and 260 C as specified package peak temperatures. The E4 comply to the new conditions with following notes : The more tough conditions will impact the MSL for a substantial part of the products; restore of the MSL will need engineering time and effort and will also depend on the availability of new materials.

5 Standardisation E4-profile vs. J-STD 020C - designed for lead-free MSL evaluation 260 C for small packages Temperature in C T P T L Tsmin Tsmax Ramp-up t p t L Ramp-down t 25 C to Peak Critical Zone T L to t p Time in s

have been tested according to the agreed

6 MSL statements Lower MSL as temporary action, qualification of new materials (ongoing) as short/mid term action Hundreds of packages in the 4 companies have been tested according to the agreed profiles, following JEDEC STD-020C for the pre-conditioning process and for failure criteria. With present materials and package design, in specific cases a drop in MSL classification may be observed Source Infineon

7 Technology Consolidated lead free solutions: For lead frame based packages Post plate of matte tin Pre plate of NiPdAu For Ball Grid Array packages SnAgCu Note: technology may differ per package family / company

8 Technology Postplate of matte tin (Sn) Main characteristics Material availability is good Closest to SnPb in cost and process Good solderability with PbSn and Pb free solders Good solderjoint reliability Whisker free process available 1) 1) See whisker presentation

9 Technology Preplate NiPdAu Main characteristics Good solderability with PbSn and Pb free solders Good solder joint reliability Used in high volume Offered by major lead frame suppliers

10 Technology SnAgCu Spheres in Ball Grid Array Main characteristics SnAg Cu is the most applied range Good solderability with Pb free solders Offered by all major suppliers Limited backward compatibility with SnPb solders (board application process to be adopted)

11 L/F packages Compatibility supplier customer Pb solder ( C) Pb solder ( C) Increase temp. by 20 C Pb component finish Today Experience of some decades of board assembly Processability: o.k. Processability: o.k. Solderability: o.k. Reliability: o.k. (NCMS-, IDEALS-report,internal evaluations) Processability: o.k. Pb Solderability: o.k. Solderability: o.k. Reliability: o.k. Reliability: o.k.

L/F packages Processability Reflow solder joints Lead containing solder Temperature in degree C 300 250 200 Backw ard Compatibility SC

degree C 300 250 200 Backward Compatibility SC, reduced dt SnAg3.8Cu0.

12 L/F packages Processability Reflow solder joints Lead containing solder Temperature in degree C Backw ard Compatibility SC SnPb36Ag2 150 FQFP HVQFN48 VSO56 50 HTQFP100 SO Time in seconds Lead-free solder Temperature in degree C Backward Compatibility SC, reduced dt SnAg3.8Cu FQFP HVQFN48 VSO56 50 HTQFP100 SO Time in seconds Only slight differences of wetting ( ), fillet ( ) Surface: less shiny for lead-free (see inserts) Source Philips

Pre-heat temperature Leaded 1.25 2.75 0.25s / 250 C 120 10 C Lead-free 1.2 3.

13 L/F packages Processability Wave solder joints Lead containing solder Lead-free solder Process Process speed [m/min] Total soldering time/temp Pre-heat temperature Leaded s / 250 C C Lead-free s / 265 C C Only difference: somewhat less shiny with lead-free Source Philips

14 L/F packages Processability Processability in lead containing vs. lead-free process For reflow soldering: paste application, component placement do not require special measures For wave soldering: glue application, component placement, glue cure do not require special measures Differences in soldering process are time and temperature SnPb plating and Sn plating do not show a different behavior in the soldering processes (more than a decade of experience!)

15 L/F packages Solderability SO 8 No forced ageing Good solderability of Sn coated components in SnPb Wetting force mn/mm Ageing : 16H150 C Wetting balance test 235 C Zero cross time << 3 seconds Wetting force >> 0.10mN/mm Ageing : 8H Steam Immersion 10seconds Source ST Microelectronics

16 L/F packages Reliability Temperature Cycling as reliability test for solder joint Temperature cycling causes thermo-mechanical solder fatigue Degradation/failure goes along the following path: Diffusion and re-crystallization Crack initiation and growth Failure by macroscopic solder fracture Solder fatigue failure is visualized and analyzed according Weibull statistics

17 L/F packages Reliability Weibull analysis of failure in temperature cycle test (-40/+125 o C) lead-free and lead-containing reflow solder Sn plated HTQFP100 components (Cu-based leadframe) HTQFP100, reflow 10 ln[1/(1-f)] 1 0,1 SnPb SnAgCu 0, N cycles Source Philips

18 % P a c k a g e s F a i l e d L/F packages Reliability 132 PQFP Board-Level Air-Air Temperature Cycling -50 C/150 C Number of Temperature Cycles Both combinations, Sn finish with SnPb solder and Sn finish with SnAgCu solder, perform equal to or better than SnPb finish with SnPb solder. Board assembly with SnPb solder paste was performed at the standard SnPb profile. Finish-Solder SnPb-SnPb1 Sn-SnPb2 SnPb-SnAgCu3 Sn-SnAgCu4 1) Current, 220 C reflow 2) Backwards compatible, 220 C reflow 3) Forwards compatible, 240 C reflow 4) Pb-free, 240 C reflow Source Freescale

19 BGA packages Compatibility supplier customer Pb solder ( C) Pb solder ( C) Increase temp. by 20 C Pb component finish Today Experience of some decades of board assembly Processabilty below 230 C critical Processability: Reliability: Processability: o.k. o.k. o.k. Pb Reliability: o.k. (improved to SnPb) Reliability: o.k. For low temperatures critical

BGA Processability Motivation: For array-package the processability has been tested. Different temperature at the ball result in different mounting height.

20 BGA Processability Motivation: For array-package the processability has been tested. Different temperature at the ball result in different mounting height. decreasing mounting height Beginning melting Conclusion: The combination lead-free BGA/SnPb-paste can be processed with a minimum temperature of 230 C (at the ball). Due to restricted self-alignment, a peak temperature at 220 C should only be chosen in exemptional cases Peak temperatures over 230 C are recommended Complete melting, final height mounting height bad joint good solder joint with limited drop good solder joint Source Infineon

21 BGA On board Reliability Lead Free solder balls shear test Source ST Microelectronics Leadfree solder balls are showing same initial shear strength than SnPb balls but shear values remains more stable during ageing

22 388 PBGA, Board-Level Air-to-Air Thermal Cycling, -40 to +125 o C Material/Ball/Paste Current/SnPbAg/SnPb Current/SnAgCu/SnAgCu Halide-Free/SnAgCu/SnAgCu Courtesy Thomas Koschmieder Source Freescale

23 BGA Reliability Lead Free solder balls pull Test 0.40mm solder ball; Pull Test on 0.35mm pad diameter (Ni/Au) Grams AVG Min. AVG Min. Source ST Microelectronics Stable Pull strength after ageing. Higher strength for lead-free balls SnPb AVG Min. SnAgCu AVG Min. Without drypack baking ; Avg Without drypack baking ; Min With drypack baking ; Avg With drypack baking ; Min

24 BGA On board Reliability LFBGA-208, Ball SnAgCu, solder SnPbAg -40 C/+125 C, 2000 cycles Results positive Further reference: for large BGA s (35x35mm) positive results shown by: Thermal Fatigue Resistance of Pb-free Second Level Interconnect ; Patrick Roubaud; SMTA 2001 Source Infineon

BGA On board Reliability Weibull analysis of failure in temperature cycle test lead-free and lead-containing reflow solder TFBGA6x6-46 with 0.

25 BGA On board Reliability Weibull analysis of failure in temperature cycle test lead-free and lead-containing reflow solder TFBGA6x6-46 with 0.4mm solder balls (both SnPb-SnAgCu) 4 tested processes SnPb balls + SnPb paste (220C) SnAgCu balls + SnPb paste (220C) SnAgCu balls +SnAgCu paste (245C) SnAgCu balls +SnAgCu paste (250C) -40 C/+125 C cycles Source ST Microelectronics

26 Compatibility Conclusion for compatibility Leadframe-package Processability: Sn plated products show identical behaviour as SnPb plated products Solderability: Sn- and NiPdAu surfaces are solderable with SnPb and Pb-free solder paste Solder joint reliability tested at >> 2000 TC does show no failure BGA-package Processability: good processabilty for temperature over 230 C Solder joint reliability is improved compared to SnPb-balls

27 Roadmap General Conversion Roadmap (BGA excluded) ST Philips IFX Freescale 1 IC Commodities IC ASICS Q2 05 Q1 05 Q2 05 Q2 05 Q2 05 Q1 05 Q2 05 Q2 05 Discrete Q1 05 done done N/A Memories Q2 05 = Q2 05 N/A Dedicated Automot.pkgs 05 Q Q3 05 The dates indicate the completion of the volume conversion to lead free 1 FSL dates represents package platform qualification completion with conversion based on customer demand.

28 Roadmap IC Package Conversion Roadmap ST Philips IFX Freescale 1 L/T/F BGA Q2 05 Q2 05 Q2 05 Q1 05 M/L/T/QFP Q1 05 Q4 04 Q1 05 Q2 05 QFN done done Q4 04 Q2 05 SO Q1 05 Q4 04 Q4 05 Q4 04 TSSOP Q205 Q1 05 done Q1 05 SSOP Q105 Q4 04 = Q1 05 PLCC Q205 Q4 04 Q2 05 Q2 05 The dates indicate completion of the volume conversion to lead-free 1 FSL dates represents package platform qualification completion with conversion based on customer demand.

29 Conclusion Leadframe packages Sn-plating or NiPdAu-plating is introduced as lead-free technologies For leadframe packages there is a full compatibility to SnPb- and Pb-free solder process BGA packages For BGA packages SnAgCu is the chosen metallurgy On board reliability is proven In the case of BGA-packages the soldering temperature must be above 230 C for processability Note: technology may differ per package family / company

30 Whiskers and Pb-free Plating

31 Comparison of Various Plating Options! +/-

32 Main Cause for Growth Most literature agrees whiskers grow because of internal compressive stress in plating layer Important: whiskers not only grow on pure Sn but also on Sn alloys; even SnPb!

33 Whisker growth not only with pure Sn! Bright Sn SnBi3 SnCu1 SnPb Source: General Dynamics

34 Reasons for Stress in Plating Irregular intermetallic formation Mismatch of CTE with leadframe Incorporation of foreign particles in plating Mismatch of crystal orientation Mechanical operations The growth of whiskers is relieving the present stress

35 Introduction Period of potential whisker growth FeNi42 L/F no whisker growth whisker see FeNi42 presentation L/F whisker countermeasure baking see this presentation no whisker growth storage conditions service life conditions tin plating board assembly/ soldering product end of life 2 years ~ 15 years

36 Experience in Tin plating within E4 Electrolytes Production line Lab scale Shipley ST-200 Shipley ST 300 Schlötter Slototin40 Pyramid Pyra Tin Lux Technic Technistan EP OMG Reel Satin 2544 LF Lucent Satin bright Tin Leadframe Material Shipley ST-150 Shipley ST-200 Shipley ST 300 Schlötter Slototin 40 Pyramid Pyra Tin Lux Technic Technistan EP OMG Reel Satin 2544 LF Atotech HSM ASTM / material number Brand name / short notification Composition C14415 C18070 C19210 C18090 C19400 C50710 C70250 C22000 K 81 / CuSn0,15 K 75 / CuCrSiTi K80 / CuFeP, KFC K62, CuSn1CrNiTi Olin 194, K 65 / CuFe2P MF 202 / CuSn2ZnP Olin 7025, K 55 / CuNi3Si1Mg MS10 Alloy Sn; <0.02 Ni/Zn 0.3 Cr; 0.35 Si; 0.07 Ti 0.1 Fe; 0.03 P 0.6 Sn; 0.4 Ni; 0.3 Cr; 0.3 Ti 2.4 Fe; 0.12 Zn; 0,03 P 2.0 Sn; 0.2 Ni; 0,15 P; 0,15 Zn 3.0 Ni; 0.65 Si, 0.15 Mg; <1.0 Zn CuZn10 FeNi42

37 Applied Test Conditions No standardised test method available! E3 combine their knowledge in joint EU-project (PROTIN) to standardise a test method and acceptance criteria. Isothermal Storage Ambient atmosphere (uncontrolled) 23 o C /93 % r.h. 55 o C /ambient humidity 30 o C /60 % r.h. 55 o C/ 85% r.h. 60 o C /93% r.h. 85 o C /85 % r.h. 5 o C/ ambient humidity Temperature Cycling -55 o C/85 o C -40 o C/85 o C -40 o C/125 o C -15 o C/85 o C -65 o C/150 o C 0 o C/125 o C 50 o C/175 o C 45 o C/85 o C Furthermore tests after preconditioning, assembly and bias No correlation of test conditions to shelf life available Different behavior depending on base material

38 Influence of Plating Thickness longest whisker in μm ,9 μm Sn 4,2 μm Sn 5,7 μm Sn 10,8 μm Sn Cu based LF- ambient storage longest whisker broken, continued with second longest time in days Observation of of strong strong dependency on on thickness may may result result in in acceleration factor factor according to to thickness Similar Similar results results available for for 4 Cu-materials and and 3 electrolytes

39 Storage conditions Test data showed that whiskers grow longest at room temperature Explanation: irregular intermetallic growth length of longest whisker in μm ,9 μm ambient longest whisker broken, continued with second longest 1,9 μm 55 C / ambient 1,9 μm 85 C / 85 % r.h. time in days

40 Whisker Mechanism on Cu based leadframes Whiskers grow because of compressive stress in the plating which is caused by irregular growth of intermetallics Cu 6 Sn 5 Tin Whisker is forced out Whisker Sn Deposit Cu Substrate Cu L/F Cu 6 Sn 5

41 Experimental: Selective Etching Cu 6 Sn 5 Sn Deposit Cu based LF

42 Intermetallic Growth 1 hour after plating 1 week after plating Intermetallic (Cu 6 Sn 5 ) grows after plating by grain boundary diffusion of Cu into Sn.

43 Calculation of Volume Change 6 Cu + 5 Sn => Cu 6 Sn 5 V V uc * m n N av Calculation of the volume change with help of X-ray data of the unit cell results in: V = / = = 3.2% Not taking into account the contribution of the reacting Cu: V = /81.4= = 57.3 % Thus: Cu 6 Sn 5 formation can result in compressive stress.

44 Protection by Postbake (1h, 150 o C) (Within 24 hours of plating) Because of higher temperature diffusion will shift from grain boundary to bulk diffusion and thus regular intermetallics Recrystallization of Sn Diffusion barrier for further intermetallic growth Annealing of stress Postbake does NOT change CTE mismatch! No whisker! Sn deposit Cu 6 Sn 5 /Cu 3 Sn Cu based LF

45 Morphology of the Intermetallics Bulk Diffusion Recrystallization 1 h 150 o C Same amount of 4 h 125 o C intermetallics! Grain Boundary Diffusion Less Recrystallization 42 days 55 o C 1 year RT

46 Diffusion barrier

47 Postbake Characteristics Postbake results in double layer of Cu 3 Sn and Cu 6 Sn 5 The average layer thickness of the resulting intermetallic is 0.7 m (+0.2/-0.3) Sn grain size 5 to 25 m No additional intermetallic after 12 months storage at ambient Postbake doesn t effect CTE mismatch

48 Whisker Formation on Tin Plated FeNi42 Results and Conclusion

49 Temperature Cycling Different Whisker Mechanism Temperature changes: Sn = ~ 23 ppm/ o FeNi42 = ~4 ppm/ o Sn FeNi42 Whisker growth on NiFe due to difference in CTE: Sn Cu FeNi42 ~23 ppm/ o ~17 ppm/ o ~4 ppm/ o

50 Introduction Major mechanism and conditions for whisker formation Copper FeNi42 Whisker Whisker Tin Cu 6 Sn 5 Cu-based L/F irregular growth of intermetallics Ni 3 Sn 4 Tin = ~23 ppm/k FeNi42 = ~4 ppm/k mismatch of cte isothermal storage at moderate temperature thermal cycling

51 Introduction Period of potential whisker growth FeNi42 L/F no whisker growth whisker see this presentation L/F whisker countermeasure baking no whisker growth storage conditions service life conditions tin plating board assembly/ soldering product end of life 2 years 15 years

52 Whisker on FeNi42 leadframes Isothermal storage of tin plated FeNi42 max. whisker length in μm Uncontrolled ambient atmosphere Further test w/o whisker formation 55 C 600 days 85 C / 85 % r.h. 6 months 60 C / 93 % r.h 3 months 150 C 1000 h 3,7 μm Sn 6,6 μm Sn 9,5 μm Sn 11,7 μm Sn 14,7 μm Sn time in days Isothermal storage does not result in whisker formation for matt Sn plated FeNi42 based components

Experimental procedure and inspection test package

5 μm matt tin Thermal cycling Optical microscope SEM on

and read number of cycles for readout (5 data per 330

53 Experimental procedure and inspection test package TSOPII μm matt tin Thermal cycling Optical microscope SEM on FeNi42 assembled modul 5 components per test condition and read number of cycles for readout (5 data per 330 leads) identify longest whisker per component overview photo photo of longest whisker per package length measurement

54 Whisker on FeNi42 Temperature cycling after board assembly Comparison of Sn- and SnPb10 plated components 120 Board assembly with SnAgCu paste and process whisker length in μm SnPb10 plating Sn plating -40 C / +85 C, 5 K/min, 30 min dwell cycles SnPb plating shows whiskers of similar size as Sn-plated components

55 Whisker on FeNi42 Temperature cycling after board assembly Comparison of Sn- and SnPb10 plated components 120 Board assembly with SnPbAg paste and process whisker length in μm SnPb10 plating Sn plating -40 C / +85 C, 5 K/min, 30 min dwell cycles SnPb plating shows whiskers of similar size as Sn-plated components

56 Summary and conclusions Whisker length after board assembly equal for Snplated and SnPb10 plated components Little influence of solder paste type and respective process for board assembly Whisker risk for Sn-plated components equal to actual SnPb standard plated components

57 E4 Whisker Test Data on Cu based leadframes

58 Test Results * whiskers found after severe corrosion and exceeding 3000 h test time. Test condition Preconditioning Non postbaked Cu leadframes Max. Whisker Time Length ( m) (h)/ # Cycles Postbaked Cu leadframe Max. Whisker Length ( m) Time (h)/ # Cycles o C, % r.h. - ~ 90 > 5000 <10 ~ o C, % simulated reflow 0 > ~ o C o C, % simulated reflow ~ o C o C, % 215 o C 0 > ~ 6000 r.h o C, % 260 o C 0 > ~ 3000 r.h o C, % 215 o C ~ 5000 r.h. with 5 V bias applied 55 o C/85% r.h - ~ 60 > 5000 < 10 ~ o C/93% r.h * ~ o C/93% r.h simulated reflow * ~ 215 o C 60 o C/93% r.h simulated reflow * ~ 260 o C 60 o C/93% r.h 215 o C ~ o C/93% r.h 260 o C ~ o C/85% r.h 260 o C 0 ~ o C/93% r.h with 215 o C ~ 30 ~ ~ V bias applied -40 o C/125 o C, TST, - ~ ~ >7 dwell -55 o C/85 o C, TST, 10 dwell - ~ ~ o C/85 o C, TST, simulated reflow - - ~ o C -55 o C/85 o C, TST, simulated reflow - - ~ o C -55 o C/85 o C, TST, 215 o C - - ~ dwell -55 o C/85 o C, TST, 260 o C - - ~ dwell -40 o C/125 o C, TST, 215 o C < 10 ~ dwell -40 o C/125 o C, TST, 20 dwell 260 o C < 10 ~

59 Whisker Observation after Postbake after Temperature Cycling -55/85-55/ C -55/ C -40/125-40/ C -40/ C Maximum Whisker Length (μm) # cycles Postbake does NOT change the mismatch of CTE!

60 60 o C/93 %RH Corrosion Toe area of QFP after > 3000 h 60 o C/93%RH Shoulder area of QFP after > 3000 h 60 o C/93%RH

61 60 o C/93 %RH X-sections Parallel crosssections after aging > 3000h Foot Shoulder Perpendicular cross-sections on foot area after aging > 3000h

62 60 o C/ 93 %RH SEM pictures on X- sections

63 Humidity Influence on Whisker Mechanism Whiskers grow because of compressive stress in the plating which is caused by irregular growth of intermetallics or oxidation/corrosion products in the Sn layer. Tin Whisker is forced out Cu 6 Sn 5 SnO Sn Deposit Cu based LF

64 JEITA Results:

65 NEMI DoE3 Test results 60 o C/93%RH

66 E4 DoE STD Cells Variable On-Board FSL Philips STM IFX Process 1 SnPb Component No Yes X X X X 2 SnPb Component reflowed (Air) No Yes X 3 SnPb reflow component No Yes X X X 4 SnPb w/snpb (Clean flux) Yes Yes X X X X X 5 Sn - Component No Yes X X 6 Sn reflowed - Component (55C/85%RH) No Yes X 6a Sn reflowed - Component (60C/93%RH) No Yes X 7 Sn reflowed - Component (Air) No Yes X X 8 Sn (No condensation) - Component No Yes X X X 8a Sn (intentional condensation) Component No Yes X X 9 Sn w/ SnPb (No clean flux) Yes Yes X X X X X X 10 Sn w/ SAC (No clean flux) Yes Yes X X X X X X X 11 Sn w/ SnPb (Clean flux) Yes Yes X X X X X X X 12 Sn w/ SAC (Clean flux) Yes Yes X X X X X X X 13 Deflash - Sn Component No No X 14 Deflash - Sn reflowed - Component No No X 15 Deflash - Sn w/ SnPb Yes No X 16 Deflash -Sn w/ SAC Yes No X 17 Sn + Ni - Component No Yes X X 19 Sn + Ni + Reflow - Component No Yes X X 20 Sn + Ni + Reflow - Component (Air) No Yes X X Denotes # of samples to be shipped to each company Color denotes cell to be shipped to partning company Pkg Type 132 PQFP 128 QFP 64 LQFP TQFP-64-8 TQFP 64-1 Fixed Variables are: Deflash, N2, 150C 1hr Bake, OSP board Leadframe CDA194 C70250 Eftec 64 FeNi42 Finish Thick ~ 10 μm > 7 μm > 7 μm <4μm > 7 μm <4μm >7μm >7μm > 7 μm 60C / 95% 60C / 93% 60C / 93% 60C / 93% 60C / 93% 60C / 93% 60C / 93% Test 60C / 90% 55C / 85% All board assembled components with Conditions intentional condensation 60C / 85%

67 Conclusions Compressive stress is the driving force in pure tin layers (without compressive stress no whiskers). Whisker growth on Copper leadframes is mainly caused by large, irregular intermetallic Cu 6 Sn 5 growth at interface substrate / plating layer. Storage in ambient atmosphere produces longest whiskers on copper leadframe (compared to all other tested storage conditions). The thicker the Sn-layer the shorter is the whisker. Countermeasures are postbake, Ni-, Ag-underlayer. Postbake 1h, 150 o C is performed after plating.

68 Conclusions II Temperature cycling may cause a maximum whisker length of 30 m on Cu leadframes. For FeNi42 the whisker risk for Sn-plated components is equal to actual SnPb standard plated components Maximum specified whisker length is 50 m for accelerated tests. After 2 years storage at ambient and/or soldering on board matt tin plated Cu-L/F, with above mentioned countermeasures, does not show evidence of whiskers.

69 Thank you

Humidity Effects on Sn Whisker Formation. ECTC NEMI workshop June 1, 2005 Dr. Marc Dittes, Dr. Pascal Oberndorff, Peng Su, Paolo Crema

Humidity Effects on Sn Whisker Formation ECTC NEMI workshop June 1, 25 Dr. Marc Dittes, Dr. Pascal Oberndorff, Peng Su, Paolo Crema Outline Overview on experimental approach Results from cross referencing