Challenges and Solutions for Cleaning No-Clean Flux Residues from Surface Mount Components Eric...

Challenges and Solutions Challenges and Solutions for Cleaning No-Clean Flux for Cleaning No-Clean Flux

Residues from Surface Residues from Surface Mount ComponentsMount Components

Eric CamdenEric Camden

Foresite, IncForesite, Inc

Kokomo, INKokomo, IN

Experimental ProcedureExperimental Procedure

Test VehicleTest Vehicle

Umpire BoardUmpire Board

Populated with LCC, Populated with LCC, TQFP, and BGATQFP, and BGA

Other parts available, Other parts available, focusing on low standoff focusing on low standoff SMT components for this SMT components for this studystudy

DOE DetailsDOE Details

In this study we looked at four groups of In this study we looked at four groups of 10 Umpire test boards with identical level 10 Umpire test boards with identical level of contaminates. 40 Umpire boards were of contaminates. 40 Umpire boards were all processed with no-clean paste and then all processed with no-clean paste and then each component area was doped with 5ml each component area was doped with 5ml of liquid flux, using a syringe to control of liquid flux, using a syringe to control application. The processing conditions are application. The processing conditions are as followsas follows

Group DetailsGroup Details

Control – Fluxed Not CleanedControl – Fluxed Not Cleaned

Group 1 – DI water only wash and rinseGroup 1 – DI water only wash and rinse

Group 2 – saponified wash with DI water Group 2 – saponified wash with DI water rinse rinse

Group 3 – saponified wash, steam Group 3 – saponified wash, steam cleaned , DI water rinse cleaned , DI water rinse

Wash DetailsWash Details

2 FPM2 FPM

140140ooFF

60 PSI Top60 PSI Top

40 PSI Bottom40 PSI Bottom

52 each 1 GPM Nozzles total for wash, 52 each 1 GPM Nozzles total for wash, rinse tank mirrors wash. rinse tank mirrors wash.

Test MatrixTest Matrix

After the cleaning process all four groups After the cleaning process all four groups of boards went through SIR testing and of boards went through SIR testing and Ion Chromatography testing to determine Ion Chromatography testing to determine the most effective cleaning approach. All the most effective cleaning approach. All SIR testing was performed to IPC TM-650 SIR testing was performed to IPC TM-650 2.6.3.3(A), and IC was performed to IPC 2.6.3.3(A), and IC was performed to IPC TM-650 2.3.28, with the IC extractions TM-650 2.3.28, with the IC extractions being performed on localized areas being performed on localized areas beneath the components after removal. beneath the components after removal.

Control Group Control Group

Control group was not Control group was not washed at all after washed at all after conditioning conditioning

Examples of BGA, Examples of BGA, LCC, and QFP on LCC, and QFP on board and underneath board and underneath componentscomponents

Control Group continuedControl Group continued

Baseline IC DataBaseline IC DataSample Description Acetate Cl- Br- NO3

- SO42- WOA Na+ NH4+ K+

Foresite Limits SMT NC <3 <3 <12 <3 <3 <25 <3 <3 <3

Control - not cleaned

Control Umpire 4 BGA 6.65 3.05 0.96 0.69 3.36 398.95 6.25 4.91 1.74

Control Umpire 4 LCC 7.61 3.71 0.21 0.53 3.44 181.24 7.15 5.61 1.36

Control Umpire 4 TQFP 8.54 4.57 0.50 0.70 3.23 155.32 6.69 6.30 1.40

Control Umpire 4 Ref. area H2 2.36 3.84 0 0.52 1.86 2.67 0.51 1.74 1.37




Control Umpire 5 Ref. area 1.92 3.36 0.06 0.69 1.16 6.54 0.65 1.42 1.88




Control Umpire 6 Ref. area 2.67 3.48 0 0.80 1.69 5.02 0.51 1.97 1.92




Control Umpire 12 Ref. area 2.65 3.69 0.06 0.65 1.22 4.24 0.53 1.96 1.84

Baseline SIR DataBaseline SIR DataBoard # Pattern Initial 24 hour 96 hour 168 hour Final

Umpire 8 BGA 1.78E+12 4.17E+07 2.88E+07 6.31E+06 1.78E+12

Umpire 8 LCC 1.67E+12 8.32E+05 8.32E+05 8.32E+05 1.20E+06

Umpire 8 TQFP 8.99E+11 6.46E+06 5.50E+06 5.01E+06 1.20E+09

Umpire 8 Head2 2.14E+11 8.32E+09 9.55E+09 1.10E+10 7.76E+11

Umpire 9 BGA 1.82E+12 3.09E+07 3.02E+07 2.29E+07 1.58E+12

Umpire 9 LCC 1.78E+11 8.32E+05 8.32E+05 8.32E+05 8.32E+05



Umpire 10 BGA 2.34E+11 8.32E+05 8.51E+05 9.55E+05 9.12E+05

Umpire 10 LCC 1.78E+12 2.63E+07 1.86E+07 1.66E+07 2.00E+09



Umpire 11 BGA 1.86E+12 3.09E+07 1.62E+07 1.29E+07 1.66E+12

Umpire 11 LCC 1.32E+11 8.32E+05 8.32E+05 8.32E+05 1.62E+06



Control ResultsControl Results

Bad.Bad.

Of course these are worse case scenario Of course these are worse case scenario type boards but good baseline data for the type boards but good baseline data for the 3 cleaned groups. 3 cleaned groups.

Group 1-IC ResultsGroup 1-IC ResultsDI water only wash and rinseDI water only wash and rinse

Sample Description Acetate Cl- Br- NO3- SO4

2- WOA Na+ NH4 + K+


DI Water Washed ONLY - Aquastorm 200 heated to 140F

Group 1 Umpire 20 BGA 2.01 3.07 0.16 0.51 1.71 135.65 2.87 2.72 1.24

Group 1 Umpire 20 LCC 5.62 3.72 0.18 0.44 3.81 104.74 3.25 7.62 2.06

Group 1 Umpire 20 TQFP 5.33 3.45 0.34 0.36 3.55 118.21 2.35 7.22 2.11

Group 1 Umpire 20 Ref. area 2.04 2.64 0.09 0.27 1.56 1.16 0.42 2.77 1.82

Group 1 Umpire 21 BGA 2.98 3.48 0.26 0.49 3.03 201.36 2.52 4.04 1.05

Group 1 Umpire 21 LCC 5.55 3.64 0.14 0.60 2.40 101.38 2.13 7.52 1.50


Group 1 Umpire 21 Ref. area 1.54 2.04 0 0.21 1.06 1.68 0.56 2.09 1.19

Group 1 Umpire 22 BGA 4.21 3.70 0.40 0.80 2.91 167.95 3.25 5.71 1.61

Group 1 Umpire 22 LCC 5.74 3.51 0.21 0.42 3.59 96.65 3.26 7.78 1.36



Group 1 Umpire 23 BGA 4.86 4.24 0.62 1.08 3.63 175.64 2.98 6.59 2.07

Group 1 Umpire 23 LCC 6.59 4.33 0.22 0.46 1.78 97.89 2.54 8.93 1.20



Group 1-SIR ResultsGroup 1-SIR ResultsDI water only wash and rinseDI water only wash and rinse

Board # Pattern Initial 24 hour 96 hour 168 hour Final

Umpire 14 BGA 2.19E+12 1.41E+08 2.95E+08 9.55E+07 1.55E+10

Umpire14 LCC 2.24E+12 2.09E+07 8.51E+07 2.24E+07 5.37E+08



Umpire 15 BGA 2.04E+12 9.33E+07 5.89E+07 5.01E+07 1.95E+10

Umpire 15 LCC 2.14E+11 4.27E+07 3.09E+07 3.02E+07 3.89E+09



Umpire 16 BGA 1.62E+12 2.14E+08 1.41E+08 9.33E+07 1.91E+08

Umpire 16 LCC 1.32E+12 4.07E+07 2.82E+07 2.82E+07 5.37E+06



Umpire 17 BGA 1.86E+12 1.38E+08 7.41E+07 6.92E+07 2.09E+09

Umpire 17 LCC 9.33E+10 3.63E+07 2.51E+07 2.69E+07 7.24E+07



Group 1 ResultsGroup 1 Results

Still Bad.Still Bad.

As expected the data after wash with DI water As expected the data after wash with DI water only is better than the control data but still only is better than the control data but still exhibits very high levels of corrosive flux exhibits very high levels of corrosive flux residues, primarily the acetate, WOA, and residues, primarily the acetate, WOA, and ammonium. DI water alone does not have ammonium. DI water alone does not have enough cleaning energy to remove the enough cleaning energy to remove the uncomplexed flux residues in tight spacesuncomplexed flux residues in tight spaces

Group 2-IC ResultsGroup 2-IC ResultsSaponified Wash/DI RinseSaponified Wash/DI Rinse


2- WOA Na+ NH4 + K+


Saponifier Washed - Aquastorm 200 heated to 140F

Group 2 Umpire 26 BGA 1.95 1.73 0.26 0.42 1.42 79.85 2.36 2.64 0.32

Group 2 Umpire 26 LCC 1.32 1.48 0.16 0.36 1.24 53.26 2.44 1.79 0.26



Group 2 Umpire 29 BGA 1.96 1.05 0.23 0.45 1.36 84.06 2.06 2.66 0.26

Group 2 Umpire 29 LCC 1.50 0.86 0.19 0.62 1.75 61.48 2.14 2.03 0.25



Group 2 Umpire 31 BGA 1.56 1.03 0.24 0.26 1.36 91.45 2.35 2.11 0.36

Group 2 Umpire 31 LCC 1.59 0.55 0.15 0.51 1.27 59.64 2.69 2.16 0.26



Group 2 Umpire 35 BGA 1.71 1.36 0.40 0.41 1.63 74.58 2.36 2.32 0.41

Group 2 Umpire 35 LCC 1.67 1.45 0.10 0.36 1.78 63.28 2.05 2.26 0.51



Group 2-SIR ResultsGroup 2-SIR ResultsSaponified Wash/DI RinseSaponified Wash/DI Rinse


Umpire 24 BGA 2.19E+12 1.17E+08 3.72E+08 9.33E+07 1.62E+10

Umpire 24 LCC 5.62E+12 2.34E+07 9.77E+07 3.47E+07 5.01E+09



Umpire 25 BGA 2.14E+12 3.02E+07 1.45E+08 6.31E+07 1.78E+10

Umpire 25 LCC 6.17E+12 1.38E+07 9.12E+07 3.72E+07 5.37E+08



Umpire 30 BGA 2.24E+12 1.12E+08 2.40E+08 1.02E+08 1.70E+09

Umpire 30 LCC 6.92E+12 2.19E+07 3.99E+07 3.55E+07 5.62E+09



Umpire 32 BGA 2.82E+12 9.33E+07 3.99E+07 1.20E+08 8.32E+08

Umpire 32 LCC 5.75E+12 2.40E+07 1.02E+07 4.37E+07 4.52E+06




Better, but not quite good enough. Better, but not quite good enough.

Group two results; wash with saponifier at 10%, Group two results; wash with saponifier at 10%, showed much better IC data overall but the showed much better IC data overall but the WOA levels are still very high and at these levels WOA levels are still very high and at these levels would pose a mid to high risk of field failures. would pose a mid to high risk of field failures. The SIR data at this level of cleanliness perform The SIR data at this level of cleanliness perform better than the first two groups, but still show better than the first two groups, but still show more failures than not. more failures than not.

Group 3-IC ResultsGroup 3-IC ResultsSaponified wash with Steam Saponified wash with Steam


2- WOA Na+ NH4 + K+


Saponifier / Steam Washed - Aquastorm 200 heated to 140F

Group 3 Umpire 36 BGA 0.26 0.59 0.24 0 0 3.54 1.05 0 0

Group 3 Umpire 36 LCC 0.35 0.63 0.22 0 0 5.63 1.03 0 0

Group 3 Umpire 36 TQFP 0.33 0.59 0.26 0 0 4.77 0.87 0 0

Group 3 Umpire 36 Ref. area 0 0.24 0 0 0 0 0.22 0 0

Group 3 Umpire 37 BGA 0.45 0.63 0.13 0 0 2.43 0.97 0 0

Group 3 Umpire 37 LCC 0.65 0.38 0.27 0 0 4.27 0.69 0 0


Group 3 Umpire 37 Ref. area 0 0.33 0.08 0 0 0 0.07 0 0

Group 3 Umpire 40 BGA 0.51 0.69 0.22 0 0 2.77 1.05 0 0

Group 3 Umpire 40 LCC 0.32 0.68 0.18 0 0 3.88 0.67 0 0


Group 3 Umpire 40 Ref. area 0 0.27 0.08 0 0 0 0.05 0 0

Group 3 Umpire 44 BGA 0.21 0.40 0.24 0 0 2.05 0.94 0 0

Group 3 Umpire 44 LCC 0.29 0.36 0.15 0 0 3.14 0.85 0 0


Group 3-SIR Results Group 3-SIR Results Saponified wash with SteamSaponified wash with Steam


Umpire 38 BGA 2.09E+12 8.68E+08 2.39E+09 8.45E+09 1.91E+12

Umpire 38 LCC 5.75E+11 4.07E+09 2.13E+09 2.04E+09 5.50E+12



Umpire 39 BGA 2.04E+12 9.20E+08 8.51E+09 2.45E+10 1.70E+12

Umpire 39 LCC 4.68E+11 8.13E+08 1.15E+09 5.37E+09 3.72E+11



Umpire 41 BGA 2.29E+12 3.72E+09 5.89E+09 2.14E+10 1.86E+12

Umpire 41 LCC 5.62E+11 9.33E+09 1.48E+09 5.75E+10 5.13E+11



Umpire 45 BGA 1.91E+12 4.90E+09 3.89E+09 9.00E+09 2.57E+12

Umpire 45 LCC 6.03E+11 5.25E+08 1.41E+09 9.62E+09 5.01E+11




Good! Good!

The test results for group 3 show acceptable The test results for group 3 show acceptable results on both the ion chromatography and SIR results on both the ion chromatography and SIR test which indicates good field performance. The test which indicates good field performance. The steam energy combined with the saponifier on steam energy combined with the saponifier on the PCB between the wash and rinse cycles of the PCB between the wash and rinse cycles of the in-line process are effective at removing all the in-line process are effective at removing all of the uncomplexed no-clean flux residues. of the uncomplexed no-clean flux residues.

ConclusionsConclusions

Sometimes more is indeed better. Sometimes more is indeed better.

With more cleaning energy applied with With more cleaning energy applied with steam pushing the saponified wash steam pushing the saponified wash underneath the low standoff components underneath the low standoff components the results are clear according to ion the results are clear according to ion chromatography and SIR testing, the more chromatography and SIR testing, the more energy you throw at it the cleaner and energy you throw at it the cleaner and more reliable the product becomes. more reliable the product becomes.

Conclusions cont.Conclusions cont.

The parameters in the study are not intended to The parameters in the study are not intended to be implemented into normal production of PCB’s be implemented into normal production of PCB’s but for rescue and remedial cleaning of but for rescue and remedial cleaning of contaminated assemblies. contaminated assemblies.

Rescue cleaning is becoming a very important Rescue cleaning is becoming a very important option for hardware found to have cleanliness option for hardware found to have cleanliness issues long after the boards are built. issues long after the boards are built.

It is of most importance to remember not to build It is of most importance to remember not to build a recipe according to flux manufacturer spec a recipe according to flux manufacturer spec sheets but to the product being built. sheets but to the product being built.

Secondary StudySecondary Study

Flux residues are introduced to PCB’s in a Flux residues are introduced to PCB’s in a number of ways. number of ways. Hand solderHand solder Selective solderSelective solder Touch upTouch up Repair and ReworkRepair and Rework

Real World ProblemsReal World Problems

A customer came to Foresite with a A customer came to Foresite with a problem with boards failing at ICT and problem with boards failing at ICT and even more after environmental testing. even more after environmental testing.

Most of the process was WS flux and the Most of the process was WS flux and the PCB’s are washed after wave with a few PCB’s are washed after wave with a few components being hand soldered after components being hand soldered after wash due to water intolerant issues.wash due to water intolerant issues.


After looking at the entire process all of the After looking at the entire process all of the thermal profiles were well within acceptability thermal profiles were well within acceptability limits on the reflow and wave solder equipment. limits on the reflow and wave solder equipment.

A large water intolerant thru-hole transformer A large water intolerant thru-hole transformer was being hand soldered after wash.was being hand soldered after wash.

Line operator was using a bottle of liquid flux to Line operator was using a bottle of liquid flux to achieve better solder joints faster without regard achieve better solder joints faster without regard to the effect of non-complexed no-clean flux has to the effect of non-complexed no-clean flux has on neighboring components. on neighboring components.


Transformer has large thermal dissipation Transformer has large thermal dissipation properties and required massive amount properties and required massive amount of heat to fully complex the NC flux, and of heat to fully complex the NC flux, and make an acceptable solder joint. make an acceptable solder joint.

Liquid flux was spreading to resistor Liquid flux was spreading to resistor network adjacent to transformer without network adjacent to transformer without being fully complexed and causing the being fully complexed and causing the failures. failures.


Customer did not want to use localized Customer did not want to use localized cleaning due to the issues with water cleaning due to the issues with water intolerant components. intolerant components.

Also did not want to use pen type de-fluxer Also did not want to use pen type de-fluxer because of the flux being under resistors. because of the flux being under resistors.

Solution?Solution?

Real World SolutionReal World Solution

Send the PCB’s through another thermal Send the PCB’s through another thermal excursion to fully complex the flux using a excursion to fully complex the flux using a reflow oven. reflow oven.

Lose the bottle of liquid flux!Lose the bottle of liquid flux!

Further education for line operators to Further education for line operators to convey how every action impacts the convey how every action impacts the quality of the boards.quality of the boards.

IC ResultsIC Results

The PCB’s were tested with ion chromatography The PCB’s were tested with ion chromatography to ensure that secondary thermal excursion was to ensure that secondary thermal excursion was effective at complexing the fluxeffective at complexing the flux

Ionic Species Cl- NO2- Br- NO3

- PO42- SO4

2- WOA

Bare Panel 0.78 0.10 0.05 0.20 0.48 2.93 0

After SMT 8.78 7.36 2.28 2.27 0 4.86 0

After Wave 370.23 0 0.28 0.28 0.02 1.42 5.37

After in line wash 1.14 0.10 0.07 0.22 0 2.20 0.37

Top side of hand solder 7.90 0.09 0.56 0.43 0.29 12.80 159.53

After secondary thermal 1.60 0.07 0.08 0.16 0.07 2.51 0.23

IC ResultsIC Results

Looking at the IC results from a localized Looking at the IC results from a localized extraction area over the resistor network extraction area over the resistor network before and after thermal excursion the before and after thermal excursion the levels of ionics is reduced to an levels of ionics is reduced to an acceptable level. acceptable level.

Final ConclusionsFinal Conclusions

Flux is goodFlux is goodActive flux after the build process is badActive flux after the build process is badThermal mass plays an important role in Thermal mass plays an important role in soldering that no flux spec sheet can adjust for. soldering that no flux spec sheet can adjust for. Flux can come from many sourcesFlux can come from many sources Selective waveSelective wave Palletized wavePalletized wave Secondary hand solder, repair/reworkSecondary hand solder, repair/rework Localized cleaningLocalized cleaning Bottles of liquid flux are among the worst offenders. Bottles of liquid flux are among the worst offenders.

Questions?Questions?

Special thanks to Special thanks to Terry Munson, Meaghan Munson, Terry Munson, Meaghan Munson, Josh Fording, Cameron Solis for Josh Fording, Cameron Solis for

support on this study. support on this study.

Eric CamdenEric CamdenForesite, IncForesite, IncKokomo, INKokomo, IN

[email protected]@residues.com

Challenges and Solutions for Cleaning No-Clean Flux Residues from Surface Mount Components Eric...

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