!
n
itio
April 2010
d
E
ial
c
e
Sp
Booth # 865
Go Greener in Your Cleaner – pH-Neutral Cleaning
Over the past 20 years, the common notion in the electronics manufacturing industry has been that alkalinity is a must to remove flux residues. However, recent studies have shown that pH-neutral defluxing agents can accomplish the same tasks while
providing numerous advantages imparted by cleaning in a pH-neutral environment.
The concept of pH was first
introduced by the Danish
chemist Søren Peder Lauritz
Sørensen at the Carlsberg
Laboratory in 1909. Sørensen suggested the notation
“pH” (power of hydrogen) as
a matter of convenience as it
abbreviates the logarithm
for the concentration of hydrogen ions in solution.
Although this definition has been superseded, pH
can be measured with a calibrated electrode in a
solution of known hydrogen ion concentration.
The pH value of pure water at 25°C (77°F) is approximately 7.0. Solutions with a pH level of less than
7.0 are acidic and solutions with a pH greater than
7.0 are basic or alkaline; pH measurements are
important in medicine, biology, chemistry, nutrition
science, environmental science and many other
applications. The other applications include but are
not limited to the electronics manufacturing industry.
Over the past 20 years, the common notion in this
field has been that alkalinity is a must to remove flux
residues.
duce more expensive products that were highly
resistant to alkaline cleaners. Additionally, chemistry
manufactureres have added corrosion inhibitors to
address some of these concerns. Unfortunately,
corrosion inhibitors only offer a temporary solution
as they merely slow the corrosion/oxidation process
and, like most chemicals, are subject to unwanted
performance fluctuations. They may produce undesired chemical reactions, lose effectiveness and
create continuous solubilization.
Recent cleaning studies have clearly shown that pHneutral products are, in some cases, more effective
than their counterparts even at concentrations as
low as 10%. Impressively, this has also been observed while cleaning some of the more challenging
lead-free, no-clean residues. A new reactivity standard has emerged. The classic acid/base reaction is
no longer included in the chemical removal pathway
of residues: The physical and chemical pathway
relies on intermolecular interactions.
manufacturers, better cleaning products add up to
substantial savings due to fewer failures, warranty
claims, rework, as well as lower assembly and
material compatibility (assembly and cleaning
equipment) costs.Neutral (neither acidic nor alkaline) product technologies offer new capabilities to
the chemical cleaning industry as well as to PCB
and cleaning equipment manufacturers. Within the
precision cleaning industry, pH-neutral cleaning
agents provide excellent cleaning results that are
comparable and in some cases superior to alkaline
products.
Furthermore, by combining the advantages of low
operating concentrations, low operating temperatures, and eliminating the need for excessive waste
water neutralizations, they are guiding the way to
greener processes worldwide.
CONTENTS:
Go Greener in Your Cleaner pH-Neutral Cleaning.
In March 2009, pH-neutral defluxing agents were
introduced. Theses agents were designed to provide
superior cleaning results, while protecting extremely
sensitive components.
Furthermore, as these
cleaning agents have a pH similar to water, they
may help customers meet stricter rinse water disposal regula- tions.
Additionally, cleaning under low standoff components (less than 1 mil) is a current industry requirement. This challenge has been met through the use
of alkaline cleaning agents. While many factors
such as surface tension, density, and viscosity play a
crucial role in a cleaning agent’s ability to penetrate low standoff spaces, ZESTRON's pH-neutral products are particularly suited for this challenge. As a
result, cleaning trials have confirmed that pH-neutral cleaning under low standoff devices is not only
possible, but in some cases advantageous.
Previously, commonly used surfactant-based (alkaline) cleaning agents have challenged manufacturers
of cleaning equipment, stencils, and labels to pro-
Since a pH-neutral environment reduces the potential for oxidation/corrosion, pH-neutral residues are
not as harmful as alkaline products. For PCB
Vapor Recovery Devices - Save
46% Annually!
Zestron News April 2010.indd 1
DI-Water vs. Chemistry: Cleaning
Under pH-Neutral Conditions.
Case Study: Process Optimization
through PCB Defluxing Trials.
ZESTRON Welcomes New Sales
Manager - Richard A. Burke.
3/17/2010 5:19:30 PM
DI-Water vs. Chemistry: Cleaning under pH-Neutral Conditions
While most cleaning processes in the North American and Asian markets rely on cleaning with DI-water only (for OA flux removal), recent market studies suggest that water is beginning to reach its cleaning limitation, favoring the use of chemistry-assisted
processes.
A common misperception in the industry has
been that introducing a cleaning agent to a DIwater process is environmentally harmful. Interestingly, the opposite is true. The combination
of low concentrations, low operating temperatures, pH-neutral cleaning agents, and significant reductions in effluent volumes offer not
only an environmentally sound process, but also
a more cost-effective one.
These facts coincide with the recent trend
towards cleaning with chemistry. First, the
increased use of lead-free solder requires higher soldering temperatures which result in more
burnt-in fluxes that are much harder to remove
as they begin to produce water-insoluble contamination. So far, the industry’s reaction has
been to adjust cleaning processes by raising
operating temperatures to above 150°F, increasing spray pressures, and lowering belt speeds to improve and
prolong the exposure time.
However, DI-water alone has a
very limited to no ability to solubilize non-ionic residues.
using test boards populated with 0603 chip
capacitors and 12 of the most used watersoluble, lead-free solder pastes. All assemblies
were reflowed in a 10 zone oven to simulate
production conditions as closely as possible. A
full factorial analysis evaluated the variables of
wash temperature, cleaning agent technology,
cleaning agent concentration, and brands of
solder pastes used. The following three hypotheses were formed:
H1: Water-soluble flux residues are becoming
harder to remove completely with DI-water
alone.
H2: Component standoffs limit the penetration
of DI-water.
H3: Low chemistry concentrations can provide
better cleaning results and widen the process
window.
Second, cleaning leaded and
lead-free water-soluble fluxes
(especially under low standoff
components) has also become a
lot more difficult. Water, with its
high surface tension of over 70
dynes/cm, cannot effectively
penetrate low standoff components while chemistry-assisted
cleaning can reduce the surface
tension to 30 dynes/cm and
below.
Part 2: Cleaning under 0603 chip capacitors
with low standoffs
With the exception of 2 cases, the chemistryassisted process outperformed straight DI-water.
An increase in temperature generally supported
slightly better results, but numerous cases showed full flux removal at temperatures as low as
120°F.
Relative concentration levels indicated that chemistry levels of 3% might be sufficient for a
variety of pastes currently used in the industry.
Only a few pastes were not cleanable indicating that the tested
chemistries seem to be chemically capable of removing most
commonly used flux residues.
Hypothesis II and III are therefore
validated.
Conclusion:
Figure 1 demonstrates that the
use of cleaning agent 1 at a 3%
concentration level, 150ºF wash
temperature and 2.0 fpm belt
speed provided up to 111% better cleaning results (reaching
100% cleanliness) underneath
the low standoff components
when compared with a pure DIwater inline cleaning process!
Figure 1: Overall Cleaning Results
Also, removing the water from
under the components presents another challenge. Some cleaning equipment is not capable
of extracting the water sufficiently in the drying
section. And, since water does not completely
remove all residues as previously discussed, it
leads to the entrapment of contamination in a
moist environment, which is a recipe for component failure.
An internal 2-part case study was conducted
Zestron News April 2010.indd 2
active concentration. This is an important conclusion as it suggests that 3% is a feasible concentration pointing to potentially lower operating temperatures when using a cleaning agent
other than DI-water. Hypothesis I is therefore
validated.
Part 1: Cleaning without components
The cleaning results for all 12 water-soluble
pastes tested on bare, reflowed assemblies
showed significant differences. The limitations
of DI-water are already becoming quite evident
when compared to a 3% and 5% chemically
supported cleaning process. Temperature and
concentration did factor into the cleaning results
for DI-water, but there was no significant difference for both chemistries between 3% and 5%
Using chemistry seems to offer a
number of previously unknown “value added”
benefits, which, in the long run, exceed those of
DI-water in terms of performance. Furthermore,
the low operating concentrations, lower temperatures, and significant reductions in effluent
volumes that are possible with a pH neutral
chemistry-assisted cleaning process offer customers a more environmentally friendly route to
addressing the limitations of DI-water cleaning.
3/17/2010 5:19:35 PM
Process Optimization through PCB Defluxing Trials
In collaboration with a leading global security company that provides innovative systems, products, and solutions for military
and commercial applications, ZESTRON investigated the possibility of improving their current process performance while reducing the overall process costs. The feasibility of using only DI-water in the future was also examined.
In the trials, 18 IPC-B-36 test
boards populated with four
68-LCC components and soldered
with a commonly used waterbased, eutectic paste were cleaned
in a spray-in-air inline cleaner
(Speedline Aquastorm AS200)
applying the same predetermined
process parameters.
ZESTRON’s ATRON® AC 205 (5%
conc.), pure DI-water (100% conc.)
and the company’s current
cleaning agent (5% conc.) were
tested at belt speeds of 1 and 2 ft/
min and with wash and rinse
temperatures of 140ºF.
but also RMA and no-clean fluxes.
A wider process window allows for
environmentally friendly cleaning by
giving the customer the flexibility to
reduce temperature, concentration
and save energy.
Interested users should, however, be
aware that due to the lack of the chemical isolation section, many cleaning
machines designed for DI-water processes are not equipped to properly
handle chemistry without modification.
Figure 1: Pass-fail Criteria
All boards were visually inspected
with a SZ 40 microscope (4- to 60-fold
magnification). The findings detailing the
observed cleanliness of each board and quad
area (i.e., 24 results per cleaning agent) were
documented. Figure 1 visually demonstrates
the pass-fail criteria.
The data obtained proved to be in accordance
with the commonly accepted limitations of DIwater. The most promising results were found
with ATRON® AC 205 as it showed full removability at a belt speed of 1ft/min across all
surfaces and under all four quad areas and, in
particular, underneath the low standoff components.
18 out of 24 quad areas (75%) examined were
surface clean. The remaining 6 quads only
showed very minor residues. DI-water, on the
other hand, only produced surface clean
results on 7 out of 24 quad areas
(less than 30%). The competing
cleaning agent provided surface
clean results for 12 out of 24 quad
areas (50%) (Figure 2).
Based on these findings, current DIwater users are advised to closely
investigate their cleanliness levels
and give some consideration to
installing a chemistry-assisted process, which will allow them to operate at lower temperatures, with a
wider window and clean not only OA
As we look ahead, making the initial
investment now will provide increased
process flexibility, greener cleaning
processes and substantial cost savings in the
future.
Figure 2: Performance Comparison
ZESTRON Welcomes New Sales Manager - Richard A. Burke
ZESTRON America
recently welcomed
Richard A. Burke to
its staff as the new
Northeast Regional
Sales Manager.
In his new role, Rich
will be responsible
for ensuring excellent customer support for
our existing and potential customers.
Zestron News April 2010.indd 3
“We are delighted to have Rich as part of
our rapidly expanding team. His vast experience and commitment to customer satisfaction will certainly complement our world class
customer support,” says Michael McCutchen,
Manager, Sales & Marketing, ZESTRON America.
accomplished sales and marketing strategist
with an extensive, and, yet, unique technical
background.
Specifically, Rich gained tremendous core
cleaning and high precision process expertise while managing Speedline’s Electrovert’s
Wave, Reflow and cleaning product lines.
With more than 23 years of professional experience and a proven track record in the
electronics manufacturing industry, Rich is an
3/17/2010 5:19:36 PM
Booth # 865
ZESTRON provides the superior technical support and know-how for precision cleaning
applications and services in the electronics
manufacturing
industry.
11285 Assett Loop
Manassas, VA 20109
Phone:
(703) 393-9880
Toll free:
(888) 999-9116
Fax:
(703) 393-8618
E-mail: [email protected]
www.zestron.com
Application Technology:
Umut Tosun
x 120
Marketing and Sales:
Michael McCutchen
x 100
Sales:
North America
Sheldon Brennan
Mexico
Cesar Gazcon
(703)-627-5194
(01152) 1-333-496-8894
ZESTRON Europe:
Ingolstadt, Germany
E-mail: [email protected]
ZESTRON China:
Shanghai, China
E-mail: [email protected]
ZESTRON South East Asia:
Kulim, Malaysia
E-mail: [email protected]
Vapor Recovery Devices – Save 46% Annually!
The ZESTRON® Demister and Condenser have been specifically developed to reduce cleaning agent losses from
automated operations in the electronics manufacturing industry leading to greener cleaning processes and cost
savings.
ZESTRON® Demister
ZESTRON® Condenser
• Active recovery of cleaning agent
from exhaust – up to 14%.
• Lower operating costs.
• Unique internal airflow design has
no negative impact on exhaust blo
wer.
• No additional blower capacity
required.
• Greener process due to reduced
VOC emissions and chemistry reco
very.
• Active recovery of cleaning agent – up
to 85% significant cost savings.
• Designed for cleaning processes using
VIGON® and ATRON® products.
• Easy maintenance and high quality
construction.
• Greener process due to reduced VOC
emissions and chemistry recovery.
Figure 1: ZESTRON® Demister
“With the newly installed ZESTRON® Condenser and the process knowledge of ZESTRON’s engineers, Zentech Manufacturing, Inc. is now saving an average of 46% of the total chemistry consumption,” says Dave Hughes, Director of
Quality, Zentech Manufacturing, Inc.
Zestron News April 2010.indd 4
3/17/2010 5:19:36 PM