Determining Critical Cleaning Process Parameters for ... Kalyan Nukala, Speaker: Kalyan Nukala, Kalyan Nukala, M.S.Chem.Eng.M.S.Chem.Eng. Application Engineer [email protected]

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Speaker: Speaker: Speaker: Speaker: Kalyan Nukala, Kalyan Nukala, Kalyan Nukala, Kalyan Nukala, M.S.Chem.Eng.M.S.Chem.Eng.M.S.Chem.Eng.M.S.Chem.Eng.Application EngineerApplication EngineerApplication EngineerApplication Engineer

[email protected]@[email protected]@zestronusa.com

Determining Critical Cleaning Determining Critical Cleaning Determining Critical Cleaning Determining Critical Cleaning Process Process Process Process Parameters for Parameters for Parameters for Parameters for QFNsQFNsQFNsQFNs

ZESTRON ZESTRON ZESTRON ZESTRON America America America America –––– Europe Europe Europe Europe –––– Asia www.zestron.com Asia www.zestron.com Asia www.zestron.com Asia www.zestron.com Copyright Copyright Copyright Copyright ZESTRONZESTRONZESTRONZESTRONZESTRON ZESTRON ZESTRON ZESTRON America America America America –––– Europe Europe Europe Europe –––– Asia Asia Asia Asia www.zestron.com www.zestron.com www.zestron.com www.zestron.com Copyright ZESTRONCopyright ZESTRONCopyright ZESTRONCopyright ZESTRON

DeterminingDeterminingDeterminingDetermining Critical Cleaning Critical Cleaning Critical Cleaning Critical Cleaning Process Process Process Process

Parameters for Parameters for Parameters for Parameters for QFNsQFNsQFNsQFNs

� Introduction

� Core Objectives

� Phase 1 Methodology

� Phase 1 Results


� Phase 2 Results

� Conclusion


IntroductionIntroductionIntroductionIntroduction

� Quad Flat No Leads (QFN) or Micro Lead Frame (MLF) packages are the fastest growing types within the electronics industry


� QFN package is similar to the Quad Flat Package except that the leads do not extend out from the package sides

� Leads are located underneath the component body posing challenges to clean flux residues after soldering

� Low standoff (1-2 mil) and the large thermal pad at the center of the component body present barriers to the complete removal of flux residues



� Partially removed or untouched residues can lead to component failure resulting from:

� Electrochemical migration resulting in dendritic growth

� Electrical leakage currents



� Introduction

� Core Objectives


� Phase 1 Results


� Phase 2 Results

� Conclusion




� Design of Experiment (DOE) developed to determine the critical cleaning process parameters for complete cleanliness underneath leadless devices or QFNs

� Study designed in two phases

Core ObjectivesCore ObjectivesCore ObjectivesCore Objectives


� Phase 1:� Determine critical wash parameters and cleaning equipment settings for the MLF-68 component

� Cleanliness assessment through visual analysis

� Phase 2: � Utilizing process parameters from Phase 1, verify cleaning results underneath various QFN configurations

� Cleanliness assessment through visual analysis and Ion Chromatography

Core ObjectivesCore ObjectivesCore ObjectivesCore Objectives


� Introduction

� Core Objectives


� Phase 1 Results


� Phase 2 Results

� Conclusion




� Substrate: ZESTRON® low standoff test board:

� MLF-68 component

� 10 mm x 10 mm body / 0.5 mm pitch

Phase 1 MethodologyPhase 1 MethodologyPhase 1 MethodologyPhase 1 Methodology

MLFMLFMLFMLF----68686868


� Paste types used:

� A: Water soluble lead free (w/s l/f)

� B: No-clean lead free (n/c l/f)

� Cleaning equipment:

� Spray-in-air inline cleaner

� Cleaning agent:

� Dynamic surfactant



� Cleaning equipment parameters evaluated:

� Wash pressures obtained:

� Full factorial analysis

4 Spray bar V4 Spray bar V4 Spray bar V4 Spray bar V----jet designjet designjet designjet design 8 Spray bar intermix design8 Spray bar intermix design8 Spray bar intermix design8 Spray bar intermix design

Top Spray Top Spray Top Spray Top Spray bars:bars:bars:bars: 85 psi85 psi85 psi85 psi 70 psi70 psi70 psi70 psi

Bottom Spray Bottom Spray Bottom Spray Bottom Spray bars:bars:bars:bars: 40 psi40 psi40 psi40 psi 40 psi40 psi40 psi40 psi

Top Top Top Top Hurricane:Hurricane:Hurricane:Hurricane: 40 psi40 psi40 psi40 psi 40 psi40 psi40 psi40 psi


FactorsFactorsFactorsFactors LevelsLevelsLevelsLevelsPaste TypePaste TypePaste TypePaste Type w/s l/fw/s l/fw/s l/fw/s l/f n/c l/fn/c l/fn/c l/fn/c l/f

Spray configurationSpray configurationSpray configurationSpray configuration 4 V4 V4 V4 V----jetjetjetjet 8 Intermix8 Intermix8 Intermix8 IntermixConcentration (%)Concentration (%)Concentration (%)Concentration (%) 5%5%5%5% 10%10%10%10% 15%15%15%15%Belt Speed (ft/min)Belt Speed (ft/min)Belt Speed (ft/min)Belt Speed (ft/min) 0.50.50.50.5 1.01.01.01.0 1.51.51.51.5


Trial #Trial #Trial #Trial # PastePastePastePaste Concentration (%)Concentration (%)Concentration (%)Concentration (%) Spray ConfigurationSpray ConfigurationSpray ConfigurationSpray Configuration Belt Speed (ft/min)Belt Speed (ft/min)Belt Speed (ft/min)Belt Speed (ft/min)1111 w/s l/fw/s l/fw/s l/fw/s l/f 5555 4 V4 V4 V4 V----jetjetjetjet 0.50.50.50.52222 w/s l/fw/s l/fw/s l/fw/s l/f 5555 4 V4 V4 V4 V----jetjetjetjet 11113333 w/s l/fw/s l/fw/s l/fw/s l/f 5555 4 V4 V4 V4 V----jetjetjetjet 1.51.51.51.54444 w/s l/fw/s l/fw/s l/fw/s l/f 5555 8 intermix8 intermix8 intermix8 intermix 0.50.50.50.55555 w/s l/fw/s l/fw/s l/fw/s l/f 5555 8 intermix8 intermix8 intermix8 intermix 11116666 w/s l/fw/s l/fw/s l/fw/s l/f 5555 8 intermix8 intermix8 intermix8 intermix 1.51.51.51.57777 w/s l/fw/s l/fw/s l/fw/s l/f 10101010 4 V4 V4 V4 V----jetjetjetjet 0.50.50.50.58888 w/s l/fw/s l/fw/s l/fw/s l/f 10101010 4 V4 V4 V4 V----jetjetjetjet 11119999 w/s l/fw/s l/fw/s l/fw/s l/f 10101010 4 V4 V4 V4 V----jetjetjetjet 1.51.51.51.510101010 w/s l/fw/s l/fw/s l/fw/s l/f 10101010 8 intermix8 intermix8 intermix8 intermix 0.50.50.50.511111111 w/s l/fw/s l/fw/s l/fw/s l/f 10101010 8 intermix8 intermix8 intermix8 intermix 111112121212 w/s l/fw/s l/fw/s l/fw/s l/f 10101010 8 intermix8 intermix8 intermix8 intermix 1.51.51.51.513131313 w/s l/fw/s l/fw/s l/fw/s l/f 15151515 4 V4 V4 V4 V----jetjetjetjet 0.50.50.50.514141414 w/s l/fw/s l/fw/s l/fw/s l/f 15151515 4 V4 V4 V4 V----jetjetjetjet 111115151515 w/s l/fw/s l/fw/s l/fw/s l/f 15151515 4 V4 V4 V4 V----jetjetjetjet 1.51.51.51.516161616 w/s l/fw/s l/fw/s l/fw/s l/f 15151515 8 intermix8 intermix8 intermix8 intermix 0.50.50.50.517171717 w/s l/fw/s l/fw/s l/fw/s l/f 15151515 8 intermix8 intermix8 intermix8 intermix 111118181818 w/s l/fw/s l/fw/s l/fw/s l/f 15151515 8 intermix8 intermix8 intermix8 intermix 1.51.51.51.5

� Water soluble lead free trial matrix:



� No-clean lead free trial matrix:

Trial #Trial #Trial #Trial # PastePastePastePaste Concentration (%)Concentration (%)Concentration (%)Concentration (%) Spray ConfigurationSpray ConfigurationSpray ConfigurationSpray Configuration Belt Speed (ft/min)Belt Speed (ft/min)Belt Speed (ft/min)Belt Speed (ft/min)19191919 n/c l/fn/c l/fn/c l/fn/c l/f 5555 4 V4 V4 V4 V----jetjetjetjet 0.50.50.50.520202020 n/c l/fn/c l/fn/c l/fn/c l/f 5555 4 V4 V4 V4 V----jetjetjetjet 111121212121 n/c l/fn/c l/fn/c l/fn/c l/f 5555 4 V4 V4 V4 V----jetjetjetjet 1.51.51.51.522222222 n/c l/fn/c l/fn/c l/fn/c l/f 5555 8 intermix8 intermix8 intermix8 intermix 0.50.50.50.523232323 n/c l/fn/c l/fn/c l/fn/c l/f 5555 8 intermix8 intermix8 intermix8 intermix 111124242424 n/c l/fn/c l/fn/c l/fn/c l/f 5555 8 intermix8 intermix8 intermix8 intermix 1.51.51.51.525252525 n/c l/fn/c l/fn/c l/fn/c l/f 10101010 4 V4 V4 V4 V----jetjetjetjet 0.50.50.50.526262626 n/c l/fn/c l/fn/c l/fn/c l/f 10101010 4 V4 V4 V4 V----jetjetjetjet 111127272727 n/c l/fn/c l/fn/c l/fn/c l/f 10101010 4 V4 V4 V4 V----jetjetjetjet 1.51.51.51.528282828 n/c l/fn/c l/fn/c l/fn/c l/f 10101010 8 intermix8 intermix8 intermix8 intermix 0.50.50.50.529292929 n/c l/fn/c l/fn/c l/fn/c l/f 10101010 8 intermix8 intermix8 intermix8 intermix 111130303030 n/c l/fn/c l/fn/c l/fn/c l/f 10101010 8 intermix8 intermix8 intermix8 intermix 1.51.51.51.531313131 n/c l/fn/c l/fn/c l/fn/c l/f 15151515 4 V4 V4 V4 V----jetjetjetjet 0.50.50.50.532323232 n/c l/fn/c l/fn/c l/fn/c l/f 15151515 4 V4 V4 V4 V----jetjetjetjet 111133333333 n/c l/fn/c l/fn/c l/fn/c l/f 15151515 4 V4 V4 V4 V----jetjetjetjet 1.51.51.51.534343434 n/c l/fn/c l/fn/c l/fn/c l/f 15151515 8 intermix8 intermix8 intermix8 intermix 0.50.50.50.535353535 n/c l/fn/c l/fn/c l/fn/c l/f 15151515 8 intermix8 intermix8 intermix8 intermix 111136363636 n/c l/fn/c l/fn/c l/fn/c l/f 15151515 8 intermix8 intermix8 intermix8 intermix 1.51.51.51.5



Zone Zone Zone Zone

1111

Zone Zone Zone Zone

2222

Zone Zone Zone Zone

3333

Zone Zone Zone Zone

4444

Zone Zone Zone Zone

5555

Zone Zone Zone Zone

6666

Zone Zone Zone Zone

7777

Zone Zone Zone Zone

8888

Zone Zone Zone Zone

9999

Zone Zone Zone Zone

10101010

Top:Top:Top:Top: 100100100100°CCCC 120120120120°CCCC 150150150150°CCCC 180180180180°CCCC 190190190190°CCCC 210210210210°CCCC 225225225225°CCCC 235235235235°CCCC 245245245245°CCCC 225225225225°CCCC

Bottom:Bottom:Bottom:Bottom: 100100100100°CCCC 120120120120°CCCC 150150150150°CCCC 180180180180°CCCC 190190190190°CCCC 210210210210°CCCC 225225225225°CCCC 235235235235°CCCC 245245245245°CCCC 225225225225°CCCC

� Lead free Reflow Profile:

� Belt Speed: 89.0 cm/min (266.4 seconds to peak temperature)



� Standoff under MLF-68 component:


2 mil2 mil2 mil2 mil


� Introduction

� Core Objectives


� Phase 1 Results


� Phase 2 Results

� Conclusion




� Cleaning results were evaluated on the surface and underneath all components

� Percentage (%) area completely cleaned on all quadrants of the MLF were assessed

� Average of these values was taken as the % cleanliness for the trial

Phase 1 ResultsPhase 1 ResultsPhase 1 ResultsPhase 1 Results


60% Clean60% Clean60% Clean60% Clean

50%50%50%50%CleanCleanCleanClean







� Overall cleanliness assessment underneath MLF-68 basis:

% cleanliness = 42.5% % cleanliness = 100%



Trial #Trial #Trial #Trial # PastePastePastePaste Concentration (%)Concentration (%)Concentration (%)Concentration (%)Spray Spray Spray Spray

ConfigurationConfigurationConfigurationConfigurationBelt Speed Belt Speed Belt Speed Belt Speed (ft/min)(ft/min)(ft/min)(ft/min)

Results (% clean)Results (% clean)Results (% clean)Results (% clean)UnderneathUnderneathUnderneathUnderneath SurfaceSurfaceSurfaceSurface

1111

w/s l/fw/s l/fw/s l/fw/s l/f

5%5%5%5%

4 V4 V4 V4 V----jetjetjetjet0.50.50.50.5 98.7598.7598.7598.75 100100100100

2222 1.01.01.01.0 97.597.597.597.5 1001001001003333 1.51.51.51.5 98.7598.7598.7598.75 1001001001004444

8 intermix8 intermix8 intermix8 intermix0.50.50.50.5 96.2596.2596.2596.25 100100100100

5555 1.01.01.01.0 93.7593.7593.7593.75 1001001001006666 1.51.51.51.5 96.2596.2596.2596.25 1001001001007777

10%10%10%10%

4 V4 V4 V4 V----jetjetjetjet0.50.50.50.5 100100100100 100100100100

8888 1.01.01.01.0 98.7598.7598.7598.75 1001001001009999 1.51.51.51.5 100100100100 10010010010010101010

8 intermix8 intermix8 intermix8 intermix0.50.50.50.5 100100100100 100100100100

11111111 1.01.01.01.0 100100100100 10010010010012121212 1.51.51.51.5 100100100100 10010010010013131313

15%15%15%15%


14141414 1.01.01.01.0 97.597.597.597.5 10010010010015151515 1.51.51.51.5 93.7593.7593.7593.75 10010010010016161616


17171717 1.01.01.01.0 92.592.592.592.5 10010010010018181818 1.51.51.51.5 92.592.592.592.5 100100100100

� Water soluble lead free cleaning results:



� No-clean lead free cleaning results:

Trial #Trial #Trial #Trial # PastePastePastePaste Concentration (%)Concentration (%)Concentration (%)Concentration (%)Spray Spray Spray Spray

ConfigurationConfigurationConfigurationConfigurationBelt Speed Belt Speed Belt Speed Belt Speed (ft/min)(ft/min)(ft/min)(ft/min)

Results (% clean)Results (% clean)Results (% clean)Results (% clean)UnderneathUnderneathUnderneathUnderneath SurfaceSurfaceSurfaceSurface

19191919

n/c l/fn/c l/fn/c l/fn/c l/f

5%5%5%5%


20202020 1.01.01.01.0 38.7538.7538.7538.75 10010010010021212121 1.51.51.51.5 5555 10010010010022222222


23232323 1.01.01.01.0 40404040 10010010010024242424 1.51.51.51.5 12.512.512.512.5 10010010010025252525

10%10%10%10%


26262626 1.01.01.01.0 25252525 10010010010027272727 1.51.51.51.5 2.52.52.52.5 10010010010028282828


29292929 1.01.01.01.0 65656565 10010010010030303030 1.51.51.51.5 42.542.542.542.5 10010010010031313131

15%15%15%15%


32323232 1.01.01.01.0 55555555 10010010010033333333 1.51.51.51.5 35353535 10010010010034343434


35353535 1.01.01.01.0 65656565 10010010010036363636 1.51.51.51.5 52.552.552.552.5 100100100100



� Water soluble and no-clean fluxes easily cleaned from MLF-68 board surface in all scenarios



� Water Water Water Water soluble flux soluble flux soluble flux soluble flux averaged 96.94% averaged 96.94% averaged 96.94% averaged 96.94% cleanliness cleanliness cleanliness cleanliness underneath all underneath all underneath all underneath all components components components components



� NoNoNoNo----clean flux averaged 45.4% clean flux averaged 45.4% clean flux averaged 45.4% clean flux averaged 45.4% cleanliness cleanliness cleanliness cleanliness underneath all underneath all underneath all underneath all components components components components











� The flux type is the most significant factor that determined cleanliness underneath the QFN component

� Improved cleaning results are achieved with:

� Higher concentration

� Slower belt speed

� Eight (8) spray bar intermix nozzle configuration





� Concentration, belt speed and spray configuration are not critical factors in cleaning water soluble fluxes from underneath the QFN component

� For no-clean fluxes, improved cleaning results are achieved with:

� Higher concentration

� Slower belt speed

� Eight (8) spray bar intermix nozzle configuration



� Introduction

� Core Objectives


� Phase 1 Results


� Phase 2 Results

� Conclusion




� Substrate used: Practical Component® PCB007 test board

� MLF-20: 5 mm x 5 mm and 0.65 mm pitch

� MLF-44: 7 mm x 7 mm and 0.5 mm pitch

� MLF-68:10 mm x 10 mm and 0.5 mm pitch

� Dual Row MLF-156: 12 mm x 12 mm and 0.5 mm pitch



� PCB007 test boards:



� PCB007 test boards built at Rochester Institute of Technology

� Screened in automatic printer

� Components placed using pick and place machine

� Reflowed in a six (6) zone industrial reflow oven

� Boards returned to ZESTRON Technical Center for cleaning

� Fluxes were at least 24 hours old



� Paste types used:

Water Soluble PastesWater Soluble PastesWater Soluble PastesWater Soluble Pastes NoNoNoNo----clean Pastesclean Pastesclean Pastesclean Pastes

Paste APaste APaste APaste A Paste EPaste EPaste EPaste E

PastePastePastePaste BBBB Paste FPaste FPaste FPaste F

Paste CPaste CPaste CPaste C Paste GPaste GPaste GPaste G

Paste DPaste DPaste DPaste D Paste HPaste HPaste HPaste H




Zone 1Zone 1Zone 1Zone 1 Zone 2Zone 2Zone 2Zone 2 Zone 3Zone 3Zone 3Zone 3 Zone 4Zone 4Zone 4Zone 4 Zone 5Zone 5Zone 5Zone 5 Zone 6Zone 6Zone 6Zone 6

Top:Top:Top:Top: 110110110110°CCCC 125125125125°CCCC 165165165165°CCCC 200200200200°CCCC 240240240240°CCCC 260260260260°CCCC

Bottom:Bottom:Bottom:Bottom: 110110110110°CCCC 125125125125°CCCC 165165165165°CCCC 200200200200°CCCC 240240240240°CCCC 260260260260°CCCC

� Belt Speed: 35.0 cm/min (287.5 seconds to peak temperature)


� Standoff under MLF-20 component:


2 mil2 mil2 mil2 mil


� Cleaning process settings (based on Phase 1 results):

Cleaning Agent:Cleaning Agent:Cleaning Agent:Cleaning Agent: Dynamic SurfactantDynamic SurfactantDynamic SurfactantDynamic Surfactant

Water Soluble Pastes:Water Soluble Pastes:Water Soluble Pastes:Water Soluble Pastes:

Cleaning Agent Concentration:Cleaning Agent Concentration:Cleaning Agent Concentration:Cleaning Agent Concentration: 10%10%10%10%

Inline Cleaner:Inline Cleaner:Inline Cleaner:Inline Cleaner:• Belt Speed:Belt Speed:Belt Speed:Belt Speed:• Spray Bar Configuration:Spray Bar Configuration:Spray Bar Configuration:Spray Bar Configuration:

0.5 ft/min0.5 ft/min0.5 ft/min0.5 ft/min8 bar intermix8 bar intermix8 bar intermix8 bar intermix

NoNoNoNo----clean Pastes:clean Pastes:clean Pastes:clean Pastes:

Cleaning Agent Concentration:Cleaning Agent Concentration:Cleaning Agent Concentration:Cleaning Agent Concentration: 15%15%15%15%

Inline Cleaner:Inline Cleaner:Inline Cleaner:Inline Cleaner:• Belt Speed:Belt Speed:Belt Speed:Belt Speed:• Spray Bar Configuration:Spray Bar Configuration:Spray Bar Configuration:Spray Bar Configuration:

0.5 ft/min0.5 ft/min0.5 ft/min0.5 ft/min8 bar intermix8 bar intermix8 bar intermix8 bar intermix



� Introduction

� Core Objectives


� Phase 1 Results


� Phase 2 Results

� Conclusion




Wash Temperature RequiredWash Temperature RequiredWash Temperature RequiredWash Temperature Required for Complete Cleanlinessfor Complete Cleanlinessfor Complete Cleanlinessfor Complete Cleanliness

PastesPastesPastesPastes MLFMLFMLFMLF----20202020 MLFMLFMLFMLF----44444444 MLFMLFMLFMLF----68686868 DualrowDualrowDualrowDualrow MLFMLFMLFMLF----156156156156

W/S W/S W/S W/S PastesPastesPastesPastes

AAAA 145145145145°°°°FFFF 145145145145°°°°FFFF 145145145145°°°°FFFF 145145145145°°°°FFFF

BBBB 145145145145°°°°FFFF 145145145145°°°°FFFF 145145145145°°°°FFFF 145145145145°°°°FFFF

CCCC 145145145145°°°°FFFF 145145145145°°°°FFFF 145145145145°°°°FFFF 145145145145°°°°FFFF

DDDD 145145145145°°°°FFFF 145145145145°°°°FFFF 145145145145°°°°FFFF 145145145145°°°°FFFF

N/C N/C N/C N/C PastesPastesPastesPastes

EEEE 145145145145°°°°FFFF 145145145145°°°°FFFF 145145145145°°°°FFFF 155155155155°°°°FFFF

FFFF 145145145145°°°°FFFF 145145145145°°°°FFFF 155155155155°°°°FFFFResidues Residues Residues Residues under under under under one one one one component component component component at at at at 155155155155°°°°FFFF

GGGG 145145145145°°°°FFFF 145145145145°°°°FFFF 145145145145°°°°FFFF 155155155155°°°°FFFF

HHHH 145145145145°°°°FFFF 145145145145°°°°FFFF 155155155155°°°°FFFF 155155155155°°°°FFFF



� Paste F exhibited residues under one Dual Row MLF-156 component, although the other two on the same board were fully clean

� All no-clean pastes required 155°F to clean under the Dual Row MLF-156

� Pastes F and H required 155°F to clean under the MLF-68 component



� Underneath MLF-20 inspection after cleaning:


� Visual Analysis: Fully clean










� Underneath Dual Row MLF-156 inspection after cleaning:





Water Soluble Pastes: Water Soluble Pastes: Water Soluble Pastes: Water Soluble Pastes: AnionsAnionsAnionsAnions andandandand Weak Organic AcidsWeak Organic AcidsWeak Organic AcidsWeak Organic Acids

Ionic SpeciesIonic SpeciesIonic SpeciesIonic SpeciesMaximum Maximum Maximum Maximum

Contamination Contamination Contamination Contamination LevelsLevelsLevelsLevels

(µg/in(µg/in(µg/in(µg/in2222))))

Paste Paste Paste Paste AAAA Paste Paste Paste Paste BBBB Paste Paste Paste Paste CCCC Paste Paste Paste Paste DDDD

Fluoride (FFluoride (FFluoride (FFluoride (F----)))) 3333 0000 0000 0.010.010.010.01 0000 0000 0000 0000 0000

Acetate (CAcetate (CAcetate (CAcetate (C2222HHHH2222OOOO2222)))) 3333 NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND

FormateFormateFormateFormate (CH(CH(CH(CH2222OOOO2222)))) 3333 NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND

Chloride (Chloride (Chloride (Chloride (ClClClCl----)))) 4444 0000 0000 0.020.020.020.02 NDNDNDND 0000 NDNDNDND 0000 0.020.020.020.02

Nitrite (NONitrite (NONitrite (NONitrite (NO2222----)))) 3333 NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND

Bromide (BrBromide (BrBromide (BrBromide (Br----)))) 10101010 2.662.662.662.66 2.262.262.262.26 1.911.911.911.91 2.012.012.012.01 2.442.442.442.44 1.991.991.991.99 2.482.482.482.48 2.142.142.142.14

Nitrate (NONitrate (NONitrate (NONitrate (NO3333----)))) 3333 NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND

Phosphate (POPhosphate (POPhosphate (POPhosphate (PO44442222----)))) 3333 0.280.280.280.28 0.240.240.240.24 0.220.220.220.22 0.280.280.280.28 0.250.250.250.25 0.320.320.320.32 0.280.280.280.28 0.220.220.220.22

Sulfate (SOSulfate (SOSulfate (SOSulfate (SO44442222----)))) 3333 NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND

WOA (Weak Organic WOA (Weak Organic WOA (Weak Organic WOA (Weak Organic Acid)(MSA)Acid)(MSA)Acid)(MSA)Acid)(MSA)

25252525 0000 0.080.080.080.08 0.030.030.030.03 0.010.010.010.01 0.020.020.020.02 0000 0000 0.010.010.010.01

ND = Not DetectedND = Not DetectedND = Not DetectedND = Not Detected



Water Soluble Pastes: Water Soluble Pastes: Water Soluble Pastes: Water Soluble Pastes: CationsCationsCationsCations

Ionic Species

Maximum Maximum Maximum Maximum Contamination Contamination Contamination Contamination

LevelsLevelsLevelsLevels


Paste Paste Paste Paste AAAA Paste Paste Paste Paste BBBB Paste Paste Paste Paste CCCC Paste Paste Paste Paste DDDD

Lithium (Li)Lithium (Li)Lithium (Li)Lithium (Li) 3333 NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND

Sodium (Na)Sodium (Na)Sodium (Na)Sodium (Na) 3333 0000 0000 0000 0000 0000 0000 0000 0000

Ammonium (NHAmmonium (NHAmmonium (NHAmmonium (NH4444)))) 3333 0.020.020.020.02 0.010.010.010.01 0000 0.020.020.020.02 0.030.030.030.03 0.030.030.030.03 0000 0000

Potassium (K)Potassium (K)Potassium (K)Potassium (K) 3333 0.060.060.060.06 0.040.040.040.04 0.010.010.010.01 0.040.040.040.04 0.050.050.050.05 0.020.020.020.02 0000 0000

Magnesium (Mg)Magnesium (Mg)Magnesium (Mg)Magnesium (Mg) 1111 NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND

Calcium (Calcium (Calcium (Calcium (CaCaCaCa)))) 1111 0.020.020.020.02 0.010.010.010.01 0.020.020.020.02 0.020.020.020.02 0.040.040.040.04 0.020.020.020.02 0.040.040.040.04 0.020.020.020.02




NoNoNoNo----clean Pastes: clean Pastes: clean Pastes: clean Pastes: Anions Anions Anions Anions and and and and Weak Weak Weak Weak Organic AcidsOrganic AcidsOrganic AcidsOrganic Acids




Paste Paste Paste Paste EEEE Paste Paste Paste Paste FFFF Paste Paste Paste Paste GGGG Paste Paste Paste Paste HHHH

Fluoride (FFluoride (FFluoride (FFluoride (F----)))) 3333 0000 0000 0000 0.250.250.250.25 0000 0000 0000 0000

Acetate (CAcetate (CAcetate (CAcetate (C2222HHHH2222OOOO2222)))) 3333 NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND

FormateFormateFormateFormate (CH(CH(CH(CH2222OOOO2222)))) 3333 NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND

Chloride (Chloride (Chloride (Chloride (ClClClCl----)))) 4444 0000 0000 0000 0000 0.010.010.010.01 0.010.010.010.01 0.010.010.010.01 0.010.010.010.01

Nitrite (NONitrite (NONitrite (NONitrite (NO2222----)))) 3333 NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND

Bromide (BrBromide (BrBromide (BrBromide (Br----)))) 10101010 2.492.492.492.49 1.911.911.911.91 1.081.081.081.08 1.191.191.191.19 0.950.950.950.95 1.391.391.391.39 1.771.771.771.77 2.232.232.232.23

Nitrate (NONitrate (NONitrate (NONitrate (NO3333----)))) 3333 NDNDNDND NDNDNDND 0.070.070.070.07 NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND

Phosphate (POPhosphate (POPhosphate (POPhosphate (PO44442222----)))) 3333 0.190.190.190.19 0.230.230.230.23 0.300.300.300.30 0.350.350.350.35 0.350.350.350.35 0.300.300.300.30 0.270.270.270.27 0.320.320.320.32

Sulfate (SOSulfate (SOSulfate (SOSulfate (SO44442222----)))) 3333 NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND

WOA (Weak Organic WOA (Weak Organic WOA (Weak Organic WOA (Weak Organic Acid)(MSA)Acid)(MSA)Acid)(MSA)Acid)(MSA)

25252525 0.010.010.010.01 0.010.010.010.01 0000 0.010.010.010.01 0.010.010.010.01 0.010.010.010.01 0000 0000




NoNoNoNo----clean Pastes: clean Pastes: clean Pastes: clean Pastes: CationsCationsCationsCations




Paste Paste Paste Paste EEEE Paste Paste Paste Paste FFFF Paste Paste Paste Paste GGGG Paste Paste Paste Paste HHHH

Lithium (Li)Lithium (Li)Lithium (Li)Lithium (Li) 3333 NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND

Sodium (Na)Sodium (Na)Sodium (Na)Sodium (Na) 3333 0.120.120.120.12 0.110.110.110.11 0.080.080.080.08 0.130.130.130.13 0.060.060.060.06 0.080.080.080.08 0.080.080.080.08 0.100.100.100.10

Ammonium (NHAmmonium (NHAmmonium (NHAmmonium (NH4444)))) 3333 0.040.040.040.04 0.030.030.030.03 0.030.030.030.03 0.020.020.020.02 0.020.020.020.02 0.020.020.020.02 0.040.040.040.04 0.030.030.030.03

Potassium (K)Potassium (K)Potassium (K)Potassium (K) 3333 0.090.090.090.09 0.130.130.130.13 0.060.060.060.06 0.100.100.100.10 0.070.070.070.07 0.070.070.070.07 0.080.080.080.08 0.100.100.100.10

Magnesium (Mg)Magnesium (Mg)Magnesium (Mg)Magnesium (Mg) 1111 NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND NDNDNDND

Calcium (Calcium (Calcium (Calcium (CaCaCaCa)))) 1111 0.010.010.010.01 0.010.010.010.01 0.020.020.020.02 0.010.010.010.01 0.010.010.010.01 0.010.010.010.01 0000 0.010.010.010.01

ND = Not ND = Not ND = Not ND = Not DetectedDetectedDetectedDetected


� Introduction

� Core Objectives


� Phase 1 Results


� Phase 2 Results

� Conclusion




Phase 1:Phase 1:Phase 1:Phase 1:

� Flux type is the most important factor to consider for achieving cleanliness underneath QFN components

� Water soluble flux residues were more easily cleaned as compared to the no-clean flux residues

� Cleaning agent concentration, wash exposure time and spray configuration are not as critical for achieving cleanliness of water soluble fluxes

ConclusionConclusionConclusionConclusion



� No-clean fluxes:

� Higher cleaning agent concentration, wash exposure time and the eight (8) spray bar manifold with the intermix nozzle technology resulted in better cleaning results underneath all QFN components

� Based on the DOE results, optimized cleaning process parameters are:

� Water soluble fluxes:

� 10%, 145°F, 0.5 ft/min, 8 spray bars

� No-clean fluxes:

� 15%, 145°F, 0.5 ft/min, 8 spray bars



Phase 2Phase 2Phase 2Phase 2::::

� Water soluble fluxes:

� All four pastes were completely cleaned

� All the QFN types were completely cleaned




� No-clean Pastes E and G:

� Completely cleaned underneath MLF-20, MLF-44 and MLF-68 components using the process parameters determined in Phase 1

� Dual Row MLF-156 were completely cleaned underneath at 155°F wash temperature

� No-clean Paste H:

� Completely cleaned underneath MLF-20 and MLF-44 components using the process parameters determined in Phase 1

� Completely cleaned underneath MLF-68 and Dual Row MLF-156 at 155°F wash temperature




� No-clean Pastes F:

� Completely cleaned underneath MLF-20, MLF-44 components using the process parameters determined in Phase 1

� Completely cleaned underneath MLF-68 components at 155°F wash temperature

� Slight residues remained under one of three Dual Row MLF-156 using 155°F wash temperature




� Specific no-clean paste types as well as the MLF size determine the process parameters required to clean underneath

� Cleanliness verified using Ion Chromatography IPC TM-650 2.3.28



� Visual inspection underneath all QFN component types used in this study as well as the Ion Chromatography results confirmed that a dynamic surfactant cleaning agent and an optimized inline cleaning process can fully clean the surface underneath low standoff MLF components!



Speaker: Speaker: Speaker: Speaker: Kalyan Nukala, Kalyan Nukala, Kalyan Nukala, Kalyan Nukala, M.S.Chem.Eng.M.S.Chem.Eng.M.S.Chem.Eng.M.S.Chem.Eng.Application EngineerApplication EngineerApplication EngineerApplication Engineer

[email protected]@[email protected]@zestronusa.com

Thank you!

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Determining Critical Cleaning Process Parameters for ... Kalyan Nukala, Speaker: Kalyan Nukala, Kalyan Nukala, M.S.Chem.Eng.M.S.Chem.Eng. Application Engineer [email protected]