Hi balakrisnan-
No-clean fluxes have been available for more than a decade but have
become more widely available, with dozens of products now available.
These fluxes are based on a wide range of chemistries and composition,
but all share the characteristics of leaving a minimal and
theoretically benign residue on electronic assemblies that does not
have to be removed with any post-solder cleaning process. Many of
these products contain a much lower solids content than traditional
fluxes — 2-3% by weight as opposed to 25-35% by weight.
(See No-Clean Technology Review below)
Synthetic fluxes have an advantage over rosin-based and water-soluble
fluxes in that 0they can be custom formulated to meet the requirements
of the application. They can be formulated to exhibit higher
printability, tack and tack time, printing life, and can be designed
to be cleaned or to be "No-cleans". There are no restrictions on the
formulation.
http://www.aat-corp.com/whynocleans.pdf.
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An Expert Looks at the Issues™ by
Dennis Bernier in Chip Scale Review Sept. 1999
Bernier is vice president, research & development for the Kester
Solder Division of Litton Industries, Des Plaines, Ill.
http://www.chipscalereview.com/9910/featuree1.htm
"There is generally wide acceptance of the mild, no- clean fluxes used
for wave soldering, hand soldering and reflow soldering with solder
paste. The cost savings experienced by not having to remove the flux
residues can be enormous. Of course, the electronics assembly must be
able to operate with the flux residue remaining. This requires the use
of a very mild flux that can pass electrical resistivity testing at
high temperature and humidity.
Complete removal of the flux residue after soldering is required for
some applications, such as military equipment, medical electronics and
some high-voltage applications. Some no-clean fluxes can be removed
effectively and some cannot."
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http://www.pprc.org/pprc/p2tech/noclean/nointro.html
Pacific Northwest Pollution Prevention Resource Center prepared a
comprehensive report on no clean technology, "No-Clean Technology
Review."
The PPRC’s investigation found that published literature about
no-clean approaches focused on one specific application: no- clean
applications for soldering in electronics assembly. Two different
types of approaches have been used to eliminate the cleaning step
required after traditional soldering: using no-clean fluxes and, very
recently, using fluxless soldering. This article focus on no-clean
fluxes and will briefly introduce fluxless soldering.
The report has overview and information on no-clean soldering can also
be found in a number of links.
Here are some major segments of the report:
Technical Issues and No-Clean Approaches
A discussion of the technical feasibility of no-clean approaches and
results that indicate visible residues are not necessarily
detrimental. Further information that using a no-clean flux does not
necessarily eliminate all cleaning in the solder area, and that use of
an alternative atmosphere, such as nitrogen, can improve the no-clean
process. Lastly, those considering a change to no-clean will require
specific testing.
No-Clean Economics
A summary of research that evaluates the conversion to and operational
costs of no-clean approaches.
Gaps in Existing No-Clean Research
An analysis of areas that merit further study.
A bibliography
Pacific Northwest Pollution Prevention Resource Center
phone: 206-352-2050, e-mail: office@pprc.org, web: www.pprc.org
--------------------
http://www.aimsolder.com/techarticles/Incompatibilities.pdf.
No-Clean Flux:The Use of Multiple Vendors Can Produce a Reliability
Time Bomb
By John Savi, Allan MacCormack and Curt Gold
in the June, 1992 edition of CIRCUITS ASSEMBLY
Discusses the diverse formulations of no clean fluxes and their
possible incompatibility.
"Incompatibilities between similar solder flux
products supplied by different vendors can
create serious product reliability problems if not
detected during initial product qualification.
Due to the multitude of new fluxes being
introduced to the industry and the proprietary
and varied nature of these formulations, such
incompatibilities are certain to arise
occasionally."
-------------------------
Three specific manufacturers data sheets:
Amtech No-Clean solder wire
Technical Data Sheet
http://www.amtechinc.com/downloads/no-clean-wire.pdf.
"Amtech No-Clean solder wire is a low residue flux core solder,
designed for hand soldering and re-work applications. The core
provides sufficient activity to solder successfully to bare copper and
other hard to solder surfaces. The blend of resin and polymer
dendrimer activator provides rapid wetting, with a clear non-corrosive
residue."
-------------
Loctite
http://www.loctite.com/pdf/soldering.pdf.
LoctiteŽ offers a full array of Multicore
solder pastes, fluxes, and accessory products
Site includes basic technical specs.
--------
Material Safety Data Sheet
for M.G. Chemicals No Clean Rosin Flux
http://www.ee.ryerson.ca:8080/~jkoch/MSDS_Sheets/MG_MSDS_835-liquid.htm
---------
Chip Scale Review
Directory of Solder Suppliers
http://www.chipscalereview.com/issues/1001/f3_01.html
---------
Hand Soldering Tips & Techniques
including discussion of various types of flux
http://www.metcal.com/tips/1.3.2.htm
------------------
Discussion of ramifications of switching to a no clean flux by circuit
board manufacturer Daytronic
"No-Clean" Soldering Compromises Cosmetics for Safety, Efficiency, and
Cost"
http://www.daytronic.com/reference/newsletters/ss2/ss2-2.htm
I hope this meets your requirements. If I can be of further assistance
please submit a request for an answer clarification.
Nellie Bly |
Clarification of Answer by
nellie_bly-ga
on
22 Sep 2002 17:52 PDT
I have been unable to find industry standards for the the composition
of no clean solder wire or mention thereof.
There are standards for performance:
"Common specifications used to test soldering pastes and fluxes
include IPC, Bellcore (Telcordia), and Japanese Industrial
Standards (JIS). The ANSI/J-STD-004 document classifies
fluxes or the flux component of soldering paste, cored wire,
and preforms. The flux is characterized as RO (rosin), RE
(resin), OR (organic) or IN (inorganic). The flux activity
level is specified as L0, L1 (low), M0, M1 (medium), H0 or
H1 (high). Various test methods, including SIR, are used to
determine the activity level of the material under test. Other
specifications, Bellcore and JIS for example, have
pass/fail criteria for the soldering paste or flux."
http://www.tracelabs.com/east/Technical%20Papers/SIR%20-%20Pan%20Pacific%202001%20-%20Hawaii.pdf.
SURFACE INSULATION RESISTANCE TESTING OF SOLDERING PASTES AND FLUXES
Renee Michalkiewicz, Janet Green, and Scott Opperhauser
Trace Laboratories East Hunt Valley, Maryland, USA
And I found a paper discussing the performance of various
formulations:
http://www.turi.org/PDF/AIM_Suraski_at_BTU_workshop.ppt.
A Study of Lead-Free Solders AIM
But, as indicated in the articles first cited, there is obviously
significant variation among products.
If you have any suggestions as to what entity might establish the
standards you are seeking, please let me know. Otherwise, I have
exhausted my search ideas.
Search Strategies: no clean flux; no clean solder wire; industry
standards no clean solder; standards solder; standards no clean
solder: standards solder compostion; standards no clean solder wire
compostition
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