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

Challenges and Solutions
for Cleaning No-Clean Flux
Residues from Surface
Mount Components
Eric Camden
Foresite, Inc
Kokomo, IN
Experimental Procedure
Test Vehicle
Umpire Board
Populated with LCC,
TQFP, and BGA
Other parts available,
focusing on low standoff
SMT components for this
study
DOE Details
In this study we looked at four groups of
10 Umpire test boards with identical level
of contaminates. 40 Umpire boards were
all processed with no-clean paste and then
each component area was doped with 5ml
of liquid flux, using a syringe to control
application. The processing conditions are
as follows
Group Details
Control – Fluxed Not Cleaned
Group 1 – DI water only wash and rinse
Group 2 – saponified wash with DI water
rinse
Group 3 – saponified wash, steam
cleaned , DI water rinse
Wash Details
2 FPM
140oF
60 PSI Top
40 PSI Bottom
52 each 1 GPM Nozzles total for wash,
rinse tank mirrors wash.
Test Matrix
After the cleaning process all four groups
of boards went through SIR testing and
Ion Chromatography testing to determine
the most effective cleaning approach. All
SIR testing was performed to IPC TM-650
2.6.3.3(A), and IC was performed to IPC
TM-650 2.3.28, with the IC extractions
being performed on localized areas
beneath the components after removal.
Control Group
Control group was not
washed at all after
conditioning
Examples of BGA,
LCC, and QFP on
board and underneath
components
Control Group continued
Baseline IC Data
Sample Description
Foresite Limits SMT NC
Acetate
Cl-
Br-
NO3-
SO42-
WOA
Na+
NH4+
K+
<3
<3
<12
<3
<3
<25
<3
<3
<3
6.65
7.61
8.54
2.36
9.42
5.78
6.07
1.92
3.05
3.71
4.57
3.84
4.14
3.64
4.25
3.36
0.96
0.21
0.50
0
0.69
0.34
0.42
0.06
0.69
0.53
0.70
0.52
0.47
0.31
0.50
0.69
3.36
3.44
3.23
1.86
2.82
3.06
3.38
1.16
398.95
181.24
155.32
2.67
385.02
187.87
148.98
6.54
6.25
7.15
6.69
0.51
5.78
4.89
4.51
0.65
4.91
5.61
6.30
1.74
6.95
4.26
4.48
1.42
1.74
1.36
1.40
1.37
1.28
1.69
1.21
1.88
9.47
10.63
8.95
2.67
4.26
4.84
3.98
3.48
0.62
0.39
0.26
0
0.53
0.69
0.89
0.80
3.44
3.60
3.29
1.69
385.45
177.62
176.54
5.02
6.95
3.97
5.24
0.51
6.99
7.84
6.60
1.97
1.70
1.88
1.27
1.92
10.33
9.85
9.52
2.65
4.42
3.50
3.51
3.69
0.37
0.34
0.34
0.06
0.69
0.47
0.59
0.65
3.06
3.39
3.51
1.22
391.24
180.36
162.71
4.24
5.77
6.52
4.54
0.53
7.62
7.27
7.02
1.96
1.21
1.88
1.65
1.84
Control - not cleaned
Control Umpire 4 BGA
Control Umpire 4 LCC
Control Umpire 4 TQFP
Control Umpire 4 Ref. area H2
Control Umpire 5 BGA
Control Umpire 5 LCC
Control Umpire 5 TQFP
Control Umpire 5 Ref. area
Control Umpire 6 BGA
Control Umpire 6 LCC
Control Umpire 6 TQFP
Control Umpire 6 Ref. area
Control Umpire 12 BGA
Control Umpire 12 LCC
Control Umpire 12 TQFP
Control Umpire 12 Ref. area
Baseline SIR Data
Board # Pattern
Umpire 8
BGA
Umpire 8
LCC
Umpire 8
TQFP
Umpire 8
Head2
Umpire 9
BGA
Umpire 9
LCC
Umpire 9
TQFP
Umpire 9
Head2
Umpire 10 BGA
Umpire 10 LCC
Umpire 10 TQFP
Umpire 10 Head2
Umpire 11 BGA
Umpire 11 LCC
Umpire 11 TQFP
Umpire 11 Head2
Initial
24 hour
96 hour
168 hour
Final
1.78E+12
4.17E+07
2.88E+07
6.31E+06
1.78E+12
1.67E+12
8.32E+05
8.32E+05
8.32E+05
1.20E+06
8.99E+11
6.46E+06
5.50E+06
5.01E+06
1.20E+09
2.14E+11
8.32E+09
9.55E+09
1.10E+10
7.76E+11
1.82E+12
3.09E+07
3.02E+07
2.29E+07
1.58E+12
1.78E+11
8.32E+05
8.32E+05
8.32E+05
8.32E+05
1.74E+12
5.37E+07
3.72E+07
2.63E+07
6.17E+11
3.98E+11
2.57E+09
1.70E+09
1.51E+09
1.78E+12
2.34E+11
8.32E+05
8.51E+05
9.55E+05
9.12E+05
1.78E+12
2.63E+07
1.86E+07
1.66E+07
2.00E+09
2.09E+11
1.00E+06
2.00E+06
1.12E+06
9.77E+05
1.62E+11
8.31E+10
1.91E+09
8.91E+09
1.12E+11
1.86E+12
3.09E+07
1.62E+07
1.29E+07
1.66E+12
1.32E+11
8.32E+05
8.32E+05
8.32E+05
1.62E+06
6.71E+11
8.13E+05
8.91E+05
8.51E+05
9.77E+05
7.59E+12
1.77E+09
1.12E+09
1.10E+09
9.12E+11
Control Results
Bad.
Of course these are worse case scenario
type boards but good baseline data for the
3 cleaned groups.
Group 1-IC Results
DI water only wash and rinse
Sam ple Description
Foresite Limits SMT NC
Acetate
Cl-
Br-
NO3-
SO42-
WOA
Na+
NH4 +
K+
<3
<3
<12
<3
<3
<25
<3
<3
<3
DI Water Washed ONLY - Aquastorm 200 heated to 140F
Group 1 Umpire 20 BGA
Group 1 Umpire 20 LCC
Group 1 Umpire 20 TQFP
Group 1 Umpire 20 Ref. area
Group 1 Umpire 21 BGA
Group 1 Umpire 21 LCC
Group 1 Umpire 21 TQFP
Group 1 Umpire 21 Ref. area
Group 1 Umpire 22 BGA
Group 1 Umpire 22 LCC
Group 1 Umpire 22 TQFP
Group 1 Umpire 22 Ref. area
Group 1 Umpire 23 BGA
Group 1 Umpire 23 LCC
Group 1 Umpire 23 TQFP
Group 1 Umpire 23 Ref. area
2.01
5.62
5.33
2.04
2.98
5.55
5.23
1.54
3.07
3.72
3.45
2.64
3.48
3.64
3.11
2.04
0.16
0.18
0.34
0.09
0.26
0.14
0.57
0
0.51
0.44
0.36
0.27
0.49
0.60
0.45
0.21
1.71
3.81
3.55
1.56
3.03
2.40
2.76
1.06
135.65
104.74
118.21
1.16
201.36
101.38
121.31
1.68
2.87
3.25
2.35
0.42
2.52
2.13
4.12
0.56
2.72
7.62
7.22
2.77
4.04
7.52
7.09
2.09
1.24
2.06
2.11
1.82
1.05
1.50
1.44
1.19
4.21
5.74
5.64
1.69
3.70
3.51
4.15
2.14
0.40
0.21
0.63
0.08
0.80
0.42
0.75
0.40
2.91
3.59
3.41
1.16
167.95
96.65
105.27
1.88
3.25
3.26
3.25
0.45
5.71
7.78
7.64
2.29
1.61
1.36
1.14
1.89
4.86
6.59
6.85
2.74
4.24
4.33
4.04
2.41
0.62
0.22
0.65
0.07
1.08
0.46
0.85
0.55
3.63
1.78
2.97
1.21
175.64
97.89
124.51
1.92
2.98
2.54
2.69
0.51
6.59
8.93
9.28
3.71
2.07
1.20
2.94
1.23
Group 1-SIR Results
DI water only wash and rinse
Board # Pattern
Umpire 14 BGA
Umpire14 LCC
Umpire 14 TQFP
Umpire 14 Head2
Umpire 15 BGA
Umpire 15 LCC
Umpire 15 TQFP
Umpire 15 Head2
Umpire 16 BGA
Umpire 16 LCC
Umpire 16 TQFP
Umpire 16 Head2
Umpire 17 BGA
Umpire 17 LCC
Umpire 17 TQFP
Umpire 17 Head2
Initial
24 hour
96 hour
168 hour
Final
2.19E+12
1.41E+08
2.95E+08
9.55E+07
1.55E+10
2.24E+12
2.09E+07
8.51E+07
2.24E+07
5.37E+08
1.74E+12
6.17E+07
1.29E+08
5.75E+07
9.55E+07
1.70E+12
1.32E+09
1.95E+09
9.12E+09
1.66E+12
2.04E+12
9.33E+07
5.89E+07
5.01E+07
1.95E+10
2.14E+11
4.27E+07
3.09E+07
3.02E+07
3.89E+09
1.91E+12
7.08E+07
3.89E+07
4.17E+07
1.91E+08
1.95E+12
8.51E+09
1.23E+09
7.76E+09
1.62E+12
1.62E+12
2.14E+08
1.41E+08
9.33E+07
1.91E+08
1.32E+12
4.07E+07
2.82E+07
2.82E+07
5.37E+06
2.04E+12
7.76E+07
4.68E+07
4.79E+07
5.79E+07
2.04E+12
4.07E+09
2.24E+09
7.94E+09
1.38E+12
1.86E+12
1.38E+08
7.41E+07
6.92E+07
2.09E+09
9.33E+10
3.63E+07
2.51E+07
2.69E+07
7.24E+07
2.00E+12
5.89E+07
3.55E+07
3.63E+07
1.86E+08
2.04E+12
9.10E+09
7.94E+09
6.76E+09
1.95E+12
Group 1 Results
Still Bad.
As expected the data after wash with DI water
only is better than the control data but still
exhibits very high levels of corrosive flux
residues, primarily the acetate, WOA, and
ammonium. DI water alone does not have
enough cleaning energy to remove the
uncomplexed flux residues in tight spaces
Group 2-IC Results
Saponified Wash/DI Rinse
Sample Description
Foresite Limits SMT NC
Acetate
Cl-
Br-
NO3-
SO42-
WOA
Na+
NH4 +
K+
<3
<3
<12
<3
<3
<25
<3
<3
<3
Saponifier Washed - Aquastorm 200 heated to 140F
Group 2 Umpire 26 BGA
Group 2 Umpire 26 LCC
Group 2 Umpire 26 TQFP
Group 2 Umpire 26 Ref. area
Group 2 Umpire 29 BGA
Group 2 Umpire 29 LCC
Group 2 Umpire 29 TQFP
Group 2 Umpire 29 Ref. area
Group 2 Umpire 31 BGA
Group 2 Umpire 31 LCC
Group 2 Umpire 31 TQFP
Group 2 Umpire 31 Ref. area
Group 2 Umpire 35 BGA
Group 2 Umpire 35 LCC
Group 2 Umpire 35 TQFP
Group 2 Umpire 35 Ref. area
1.95
1.32
1.36
0.84
1.96
1.50
1.27
0.91
1.73
1.48
1.10
1.09
1.05
0.86
1.04
1.30
0.26
0.16
0.06
0.04
0.23
0.19
0.22
0.06
0.42
0.36
0.25
0.33
0.45
0.62
0.58
0.31
1.42
1.24
1.49
0.78
1.36
1.75
1.27
1.07
79.85
53.26
74.11
0.22
84.06
61.48
78.11
0.58
2.36
2.44
2.63
0.41
2.06
2.14
2.17
0.15
2.64
1.79
1.84
1.14
2.66
2.03
1.72
1.23
0.32
0.26
0.25
0.17
0.26
0.25
0.34
0.28
1.56
1.59
1.47
0.84
1.03
0.55
1.14
0.98
0.24
0.15
0.42
0.06
0.26
0.51
0.22
0.09
1.36
1.27
1.32
0.89
91.45
59.64
81.41
1.02
2.35
2.69
2.48
0.34
2.11
2.16
1.99
1.14
0.36
0.26
0.25
0.36
1.71
1.67
1.30
0.84
1.36
1.45
1.22
1.48
0.40
0.10
0.23
0.03
0.41
0.36
0.26
0.35
1.63
1.78
1.54
0.95
74.58
63.28
74.61
0.59
2.36
2.05
2.65
0.37
2.32
2.26
1.76
1.14
0.41
0.51
0.36
0.28
Group 2-SIR Results
Saponified Wash/DI Rinse
Board # Pattern
Umpire 24 BGA
Umpire 24 LCC
Umpire 24 TQFP
Umpire 24 Head2
Umpire 25 BGA
Umpire 25 LCC
Umpire 25 TQFP
Umpire 25 Head2
Umpire 30 BGA
Umpire 30 LCC
Umpire 30 TQFP
Umpire 30 Head2
Umpire 32 BGA
Umpire 32 LCC
Umpire 32 TQFP
Umpire 32 Head2
Initial
24 hour
96 hour
168 hour
Final
2.19E+12
1.17E+08
3.72E+08
9.33E+07
1.62E+10
5.62E+12
2.34E+07
9.77E+07
3.47E+07
5.01E+09
2.09E+12
2.75E+07
1.07E+08
4.27E+07
8.91E+09
2.09E+12
1.07E+09
1.95E+09
8.91E+09
1.48E+12
2.14E+12
3.02E+07
1.45E+08
6.31E+07
1.78E+10
6.17E+12
1.38E+07
9.12E+07
3.72E+07
5.37E+08
2.00E+12
1.91E+07
1.26E+07
4.68E+07
1.78E+10
2.04E+12
1.15E+09
2.82E+09
3.79E+09
1.78E+12
2.24E+12
1.12E+08
2.40E+08
1.02E+08
1.70E+09
6.92E+12
2.19E+07
3.99E+07
3.55E+07
5.62E+09
1.95E+12
2.95E+07
2.02E+07
4.68E+07
1.38E+10
2.00E+12
8.71E+09
1.86E+10
8.71E+10
1.07E+12
2.82E+12
9.33E+07
3.99E+07
1.20E+08
8.32E+08
5.75E+12
2.40E+07
1.02E+07
4.37E+07
4.52E+06
1.70E+12
2.69E+07
1.29E+07
6.92E+07
1.38E+09
1.74E+12
1.17E+09
2.09E+09
1.26E+09
1.48E+12
Group 2 Results
Better, but not quite good enough.
Group two results; wash with saponifier at 10%,
showed much better IC data overall but the
WOA levels are still very high and at these levels
would pose a mid to high risk of field failures.
The SIR data at this level of cleanliness perform
better than the first two groups, but still show
more failures than not.
Group 3-IC Results
Saponified wash with Steam
Sample Description
Foresite Limits SMT NC
Acetate
Cl-
Br-
NO3-
SO42-
WOA
Na+
NH4 +
K+
<3
<3
<12
<3
<3
<25
<3
<3
<3
Saponifier / Steam Washed - Aquastorm 200 heated to 140F
Group 3 Umpire 36 BGA
Group 3 Umpire 36 LCC
Group 3 Umpire 36 TQFP
Group 3 Umpire 36 Ref. area
Group 3 Umpire 37 BGA
Group 3 Umpire 37 LCC
Group 3 Umpire 37 TQFP
Group 3 Umpire 37 Ref. area
Group 3 Umpire 40 BGA
Group 3 Umpire 40 LCC
Group 3 Umpire 40 TQFP
Group 3 Umpire 40 Ref. area
Group 3 Umpire 44 BGA
Group 3 Umpire 44 LCC
Group 3 Umpire 44 TQFP
0.26
0.35
0.33
0
0.59
0.63
0.59
0.24
0.24
0.22
0.26
0
0
0
0
0
0
0
0
0
3.54
5.63
4.77
0
1.05
1.03
0.87
0.22
0
0
0
0
0
0
0
0
0.45
0.65
0.36
0
0.63
0.38
0.49
0.33
0.13
0.27
0.16
0.08
0
0
0
0
0
0
0
0
2.43
4.27
3.29
0
0.97
0.69
0.55
0.07
0
0
0
0
0
0
0
0
0.51
0.32
0.22
0
0.21
0.29
0.25
0.69
0.68
0.58
0.27
0.40
0.36
0.45
0.22
0.18
0.21
0.08
0.24
0.15
0.24
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2.77
3.88
3.54
0
2.05
3.14
3.33
1.05
0.67
0.39
0.05
0.94
0.85
0.62
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Group 3-SIR Results
Saponified wash with Steam
Board # Pattern
Umpire 38 BGA
Umpire 38 LCC
Umpire 38 TQFP
Umpire 38 Head2
Umpire 39 BGA
Umpire 39 LCC
Umpire 39 TQFP
Umpire 39 Head2
Umpire 41 BGA
Umpire 41 LCC
Umpire 41 TQFP
Umpire 41 Head2
Umpire 45 BGA
Umpire 45 LCC
Umpire 45 TQFP
Umpire 45 Head2
Initial
24 hour
96 hour
168 hour
Final
2.09E+12
8.68E+08
2.39E+09
8.45E+09
1.91E+12
5.75E+11
4.07E+09
2.13E+09
2.04E+09
5.50E+12
1.95E+12
2.63E+09
1.70E+09
1.02E+10
1.78E+12
2.00E+12
4.72E+09
3.02E+09
4.17E+09
1.95E+12
2.04E+12
9.20E+08
8.51E+09
2.45E+10
1.70E+12
4.68E+11
8.13E+08
1.15E+09
5.37E+09
3.72E+11
1.91E+12
9.33E+08
2.04E+09
9.33E+09
1.58E+12
1.66E+12
1.38E+09
5.13E+09
2.57E+09
1.48E+12
2.29E+12
3.72E+09
5.89E+09
2.14E+10
1.86E+12
5.62E+11
9.33E+09
1.48E+09
5.75E+10
5.13E+11
1.82E+12
1.29E+09
2.19E+09
1.32E+10
1.41E+12
1.91E+12
9.55E+09
2.19E+10
1.20E+10
2.04E+12
1.91E+12
4.90E+09
3.89E+09
9.00E+09
2.57E+12
6.03E+11
5.25E+08
1.41E+09
9.62E+09
5.01E+11
1.66E+12
1.00E+09
1.74E+09
1.19E+10
6.31E+11
1.74E+12
1.66E+09
2.63E+09
3.72E+09
1.78E+12
Group 3 Results
Good!
The test results for group 3 show acceptable
results on both the ion chromatography and SIR
test which indicates good field performance. The
steam energy combined with the saponifier on
the PCB between the wash and rinse cycles of
the in-line process are effective at removing all
of the uncomplexed no-clean flux residues.
Conclusions
Sometimes more is indeed better.
With more cleaning energy applied with
steam pushing the saponified wash
underneath the low standoff components
the results are clear according to ion
chromatography and SIR testing, the more
energy you throw at it the cleaner and
more reliable the product becomes.
Conclusions cont.
The parameters in the study are not intended to
be implemented into normal production of PCB’s
but for rescue and remedial cleaning of
contaminated assemblies.
Rescue cleaning is becoming a very important
option for hardware found to have cleanliness
issues long after the boards are built.
It is of most importance to remember not to build
a recipe according to flux manufacturer spec
sheets but to the product being built.
Secondary Study
Flux residues are introduced to PCB’s in a
number of ways.




Hand solder
Selective solder
Touch up
Repair and Rework
Real World Problems
A customer came to Foresite with a
problem with boards failing at ICT and
even more after environmental testing.
Most of the process was WS flux and the
PCB’s are washed after wave with a few
components being hand soldered after
wash due to water intolerant issues.
Real World Problems
After looking at the entire process all of the
thermal profiles were well within acceptability
limits on the reflow and wave solder equipment.
A large water intolerant thru-hole transformer
was being hand soldered after wash.
Line operator was using a bottle of liquid flux to
achieve better solder joints faster without regard
to the effect of non-complexed no-clean flux has
on neighboring components.
Real World Problems
Transformer has large thermal dissipation
properties and required massive amount
of heat to fully complex the NC flux, and
make an acceptable solder joint.
Liquid flux was spreading to resistor
network adjacent to transformer without
being fully complexed and causing the
failures.
Real World Problems
Customer did not want to use localized
cleaning due to the issues with water
intolerant components.
Also did not want to use pen type de-fluxer
because of the flux being under resistors.
Solution?
Real World Solution
Send the PCB’s through another thermal
excursion to fully complex the flux using a
reflow oven.
Lose the bottle of liquid flux!
Further education for line operators to
convey how every action impacts the
quality of the boards.
IC Results
The PCB’s were tested with ion chromatography
to ensure that secondary thermal excursion was
effective at complexing the flux
Ionic Species
Bare Panel
After SMT
After Wave
After in line wash
Top side of hand solder
After secondary thermal
Cl0.78
8.78
370.23
1.14
7.90
1.60
-
NO2
0.10
7.36
0
0.10
0.09
0.07
Br0.05
2.28
0.28
0.07
0.56
0.08
-
NO3
0.20
2.27
0.28
0.22
0.43
0.16
2-
PO4
0.48
0
0.02
0
0.29
0.07
2-
SO4
2.93
4.86
1.42
2.20
12.80
2.51
WOA
0
0
5.37
0.37
159.53
0.23
IC Results
Looking at the IC results from a localized
extraction area over the resistor network
before and after thermal excursion the
levels of ionics is reduced to an
acceptable level.
Final Conclusions
Flux is good
Active flux after the build process is bad
Thermal mass plays an important role in
soldering that no flux spec sheet can adjust for.
Flux can come from many sources





Selective wave
Palletized wave
Secondary hand solder, repair/rework
Localized cleaning
Bottles of liquid flux are among the worst offenders.
Questions?
Special thanks to
Terry Munson, Meaghan Munson,
Josh Fording, Cameron Solis for
support on this study.
Eric Camden
Foresite, Inc
Kokomo, IN
[email protected]