Optimizing batch cleaning for removing lead-free flux residues on PCAs
lower chemical usage, higher throughput, area array components. Fan and coherent spray when cleaning under the Z-axis is needed.
and ultimately, a lower cost to clean. nozzles were studied to determine the optimal Steve Stach is the CEO and President of
As mentioned in the introduction of the energy source for removing trapped flux residues. Austin American Corporation. Steve has more
paper, global environmental mandates are The data findings indicated the importance of than 30 years experience in designing electronic
real and require reduction and elimination fluid flow, pressure at the board surface and assembly cleaning systems. Steve’s contact infor-
of lead, volatile organic compounds (VOCs) directional forces. From this research, progressive mation: sstach@aat-corp.com.
and other pollutants from our product energy dynamics was developed. Dr. Mike Bixenman is the CTO and
and our production lines. Understanding This year’s research focused on process co-founder of Kyzen Corporation. Mike has
the thermodynamics of cleaning can help equivalence. The data findings indicate the im- twenty years experience in designing cleaning and
to minimize environmental impacts and portance of wash temperature effects when using optimizing electronic assembly cleaning materials.
improve the cleaning at the same time. batch dishwasher systems. Additionally, the re- Mike’s contact information: mikeb@kyzen.com.
search finds the importance of soil effects and the
references selection of solder pastes that form soft residues
[1] Wack, H., Becht, J., Ph.D., Tosun, U.,
& Ellis, D. (2007, April). A New Defini-
tion of Low Stand Off Cleaning. Apex/
IPC Technical Forum. L.A Convention
Center
[2] Wack, H., Becht, J., Ravindran, N.,
Tosun, U., Chamousset, S., & Stach,
S. (2008, April). Fluid Flow Mechanics Reference Books
-Key to Low Standoff Cleaning. Apex/
IPC Technical Forum. Las Vegas, NV

[3] Bixenman, M. (2008, April). Engineered
by Dr. Jennie Hwang
Cleaning fluids Designed for Batch
Processing. Apex/IPC Technical Forum.
Las Vegas, NV
[4] Stach, S., & Bixenman, M. (2004, Sep).
Optimizing Cleaning Energy in Batch
and Inline Spray Systems. SMTAI Tech-
TO ORDER:
Online: www.LeadFreeService.com Fax: 216-896-0405
nical Forum, Rosemont, IL: Donald
Stephens Convention Center.
Dr. Hwang’s upcoming Lead-free lectures/seminars
[5] Rosin Data Sheet, www.penglaichem.
Visit: www.LeadFreeService.com
com
[6] Bixenman, M., & Stach, S. (2007,
Oct). Development and validation of a
new test platform for cleaning process
development. SMTAI Technical Forum,
Orlando, FL.
This research paper is fifth in a series written by
Stach and Bixenman on optimizing electronic
cleaning processes presented each year at the
SMTAI conference. From these research efforts,
key developments have improved cleaning process
understanding.
The Process Cleaning Rate theorem infers
that the static cleaning rate (chemical and
temperature influences) plus the dynamic clean
rate (mechanical influences) equals the process
cleaning rate. Based on this theorem, follow on
research focused on cleaning material, soil, and
dynamic energy effects.
Using glass area array test vehicles, the
research findings indicate different removal rates
for different solder paste flux residues. Soft resi-
dues were bridged rapidly from cleaning material
and energy effects. Hard residues require more
time and removed in layers similar to peeling a
union.
Nozzle types were studied to understand
dynamic energy needed to bridge flux residue
trapped under Z-axis components. Glass test ve-
hicles were bumped using anisotropic adhesive as
BookAD020708.indd 1 2/8/2008 8:38:13 AM
www.globalsmt.net Global SMT & Packaging – September 2008 – 19
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