United States Environmental Protection Agency
Washington, D.C. 20460
Office of Solid Waste and Emergency Response
July 12, 1994
Mr. Christopher R. Rhodes
Director of Environmental, Safety & Governmental
Relations Programs, IPC
7380 N. Lincoln Avenue
Lincolnwood, Illinois 60646-1705
Dear Mr. Rhodes:
This letter is in response to your March 9, 1994 letter in which
you requested a regulatory interpretation regarding photoresist
solids ("skins") generated in the printed circuit board
manufacturing industry. You asked for a decision as to whether
these wastes are or are not F006 listed hazardous waste. This
longstanding issue arose originally when the Virginia Department
of Environmental Quality asked EPA's Region III office for assistance
in making a site specific hazardous waste determination at a printed
circuit board manufacturing facility in Virginia.
We have reviewed the data available to us, including the State
and Regional interpretations you have provided, and have conducted
further analyses of the manufacturing processes involved. Based
on this review, I have made the following determination regarding
the status of photoresist solids.
For the reasons stated below, we cannot categorically state that
photoresist solids generated in stripping operations are not F006
wastes. Their regulatory status is dependent on the type of operation
employed at each individual facility. Therefore, the determination
as to whether or not skins are hazardous waste will be dependent
on the analysis of the individual facility by the State or Regional
regulatory authority. Regulatory authorities should make this
determination based on the following interpretation of the F006
hazardous waste listing description:
_ The crux of this issue is whether the stripping of photoresist
solids from printed circuit boards is an electroplating operation
included within the scope of the F006 listing as defined by the
Agency in the Interpretative Rule on this subject which was published
in the Federal Register on December 2, 1986 (51 FR 43350). Please
note that although the printed circuit board manufacturing industry
is no longer specifically identified in the F006 listing as a
result of the December 2, 1986 interpretive rule (51 FR 43350),
the processes used (e.g., electroplating, chemical etching, and
cleaning and stripping) may still cause wastewater treatment sludges
to meet the F006 listing. The interpretive rule was merely a correction
to reflect the Agency's policy of referring to "processes"
only, rather than specific industries in the "non-specific
source" F listings; the notice did not otherwise change the
scope of the listing with respect to the printed circuit board
industry. This was also explained in the attached memorandum from
Sylvia K. Lowrance, Director, Office of Solid Waste, to Ted A.
Hopkins of the Oregon Department of Environmental Quality.
If stripping solutions are within the scope of the listing and
are, therefore, electroplating wastewaters, the filtering of skins
from that solution should be considered the generation of wastewater
treatment sludge from electroplating operations and thus would
be considered F006 listed hazardous wastes. If stripping solutions
are not electroplating wastewaters then the skins would not be
wastewater treatment sludges and thus not F006.
_ Because the "cleaning and stripping" subcategory of
electroplating operations is a conditional one (cleaning and stripping
operations are only defined as electroplating operations when
they are associated with common and precious metals electroplating,
anodizing, or chemical etching and milling operations), and because
there has not been specific guidance issued as to when there is
a strong enough "association" between a cleaning and
stripping operation and another included process, we are issuing
the following determination as to when a cleaning or stripping
operation is defined as an electroplating operation for purposes
of the F006 listing:
- If the stripping operation is in line with or contiguous with
an electroplating operation, then the stripper solution itself
becomes an electroplating wastewater. "In line with or contiguous
with" in this case would mean the stripping operation is
not physically separated from these operations and the printed
circuit boards are not rinsed and dried prior to the photoresist
stripping operation. The stripper solutions thus could be mixed
or intermingled with electroplating wastewater.
Photoresist solids generated in this case would be F006 wastes.
- If the stripping operation is not in line with or contiguous
with an electroplating operation the stripping solution itself
does not become anelectroplating wastewater.
Photoresist solids generated in this case would not be F006 wastes.
The rationale for this interpretation is based on the intent of
the listing of F006 wastewater treatment sludges. F006 hazardous
wastes were listed for reasons explained in the November 14, 1980
RCRA Background Document for listed hazardous wastes. Among the
reasons was the conclusion that these wastes frequently contain
cadmium, hexavalent chromium, nickel, and complexed cyanide in
significant concentrations. The listing process is designed to
insure that wastes which meet the listing criteria are managed
as hazardous wastes. (Please note that wastes which meet the listing
description but do not contain the constituents or do not exhibit
the properties for which they were listed can petition the Agency
or authorized State for a site-specific exclusion). If there is
any possibility of skins stripping solutions being mixed or commingled
with other electroplating wastewater, or if the hazardous constituents
generated by other electroplating processes can otherwise be "carried
forward" by the nature of the association of the two processes,
the skins themselves could become contaminated with these hazardous
Our analysis suggests that physical separation of the two operations
together with rinsing and drying operations of printed circuit
boards prior to stripping serve to prevent the carryover of potential
hazardous contaminants from the electroplating and etching operations
to the stripping operation.
Conversely, our analysis suggests the lack of separation and rinsing
and drying operations can result in the carryover of wastewater
from the electroplating processes into the stripping solution.
In these cases, the filtering of the skins from the contaminated
stripping solution would constitute treatment of an electroplating
wastewater and would result in the generation of F006.
Although skins may in some cases be determined to not be F006
listed hazardous waste under federal regulations, the skins may
be subject to more stringent state or local regulations. However,
even if the skins do not meet the listing description for federal
or state regulations, they are still subject to evaluation for
hazardous waste characteristics, as specified at 40 CFR Part 261
The Agency may revisit this issue at a later time based on new
information or facts which it may gather.
Thank you for your patience in this matter. If you have any further
questions, please contact Rick Brandes of my staff at (202)
Michael Shapiro, Director
Office of Solid Waste
cc: Waste Management Division, Directors, Regions I - X
7380 N. Lincoln Avenue
Lincolnwood, Illinois 60646-1705
March 9, 1994
Mr. Michael Shapiro
Director, Office of Solid Waste
U.S. Environmental Protection Agency
401 M Street, SW/5301
Washington, D.C. 20460
Dear Mr. Shapiro:
For almost two years, the IPC and the American electronic interconnection
industry have been seeking a resolution from your office on a
regulatory interpretation problem brought about by the EPA Region
III office. Unfortunately, we have still received no written response.
Therefore, we are writing you today on behalf of the 800 independent
circuit board manufacturers in the United States and strongly
requesting an expedited resolution of this issue.
To briefly restate the issue, on 24 June 1991, John Humphreys,
Chief of the General States Permits Section for U.S. EPA Region
III, issued a written interpretation to a PWB fabrication facility
in Virginia that photoresist solids separated from the facility's
stripper solution (commonly called "skins") should be
classified as a hazardous waste, designated as F006. As you know,
the RCRA waste code F006 is reserved for waste water treatment
sludges from electroplating operations.
Mr. Humphreys' decision was apparently based on two opinions.
First, Mr. Humphreys considered an in-process filtration operation
that separates photoresist solids from the stripper solution in
order to recycle the stripper solution to be a waste treatment
operation. In addition, Mr. Humphreys considered the residue resulting
from the recovery of the resist stripping solution to be a categorical
hazardous waste because of its connection with electroplating
operations. A copy of Mr. Humphreys' letter is enclosed.
This issue has been carefully reviewed by members of the IPC Environmental,
Health, Safety & Transportation (EHST) Committee, as well
as several industry suppliers who provide photorisist for circuit
board manufacturing and other uses. After carefully reviewing
all facts including process flow information, TCLP data, and other
regulatory documents, IPC's EHST Committee feels that Mr. Humphreys'
interpretation is erroneous for numerous reasons.
First of all, we disagree that solids filtered from an in-process
recycle loop should be considered "waste water treatment
sludges." This filtration process is a closed recycle loop,
and the resist skins are filtered out to prevent plugging of spray
nozzles, prevent redeposition on panels, and prolong bath life
for the stripper solution. Such a closed loop recycling system
qualifies for the 261.4 (a)(8) "closed-loop" exemption.
Second, we argue that photoresist skins are not categorical F006
waste because they are not inherently connected to the plating
operation. Photoresist application and stripping is distinct from
electroplating in PWB manufacturing. In fact, in some cases, no
electroplating appears anywhere in the manufacturing process at
all. This operation is called "print and etch" in which
a photoresist pattern is applied to copper clad laminate, which
is then etched prior to photoresist stripping.
In addition, the IPC has collected TCLP data from more than 20
companies on their photoresist skins and solid residues. All samples
passed the TCLP test. None showed toxicity characteristics high
enough to be classified as characteristic hazardous waste. In
order to properly monitor and control the filtered skins, IPC
encourages all of its members to conduct periodic TCLP testing
on the skin residues. We feel that these photoresist skins are
already properly regulated through the present TCLP testing regimens.
Despite letters and supporting data from the IPC (enclosed) and
state EPAs as well as extensive communication from DuPont and
other photoresist suppliers, we have still received no written
clarification or resolution of this issue from the Federal EPA
office. As a result, the Region III interpretation has caused
industry-wide confusion and is increasing waste handling costs
for circuit board manufacturers without yielding any environmental
benefit. Capturing non-hazardous photoresist solids under the
RCRA F006 classification greatly increases manufacturing costs
while using up precious hazardous waste landfill capacity that
is needed for genuine hazardous waste.
If the Region III ruling is allowed to stand, it could add up
to 10 million pounds annually to the national hazardous waste
stream. This unnecessary and costly expense would further reduce
the competitiveness of an industry already hard pressed by foreign
competitors operating under less stringent environmental and safety
While waiting for a response from your office, a number of IPC
member companies or regional circuit associations have proceeded
with seeking interpretations from the state and local authorities.
We have enclosed copies of all such rulings received to date.
Thus far, every single state ruling has contradicted the Region
For these reasons, we feel that the Region III decision is clearly
erroneous and should be overturned by your office. We respectfully
ask that you please expedite resolution of this issue at your
earliest convenience. If you need additional information or have
questions, we would be happy to discuss this issue and answer
and questions at your convenience. Thank you for your time and
Christopher R. Rhodes
Director of IPC
Environmental Safety & Government Relations
Dr. John Lott
Senior Technical Consultant
Chairman, IPC HST Programs
cc: Rick Brandes, Chief
Waste Identification Branch
DuPont Electronic Materials
14 TW Alexander Drive, P.O. Box 13999
Research Triangle Park, North Carolina 27709-3999
Chronology of Appeal on Resist Skins
_ June 16, 1992 - DuPont letter to U.S. EPA asking for
clarification on why resist stripper skins and sludge were
classified as F006 classification, based on industry data that
there were no hazardous materials in the skins and sludge.
_ July 2, 1992 - IPC letter on behalf of the industry was sent
Sylvia Lowrance, USEPA, asking that a clarification and
reconsideration be made of EPA Region III decision on F006
classification for photoresist skins.
_ Feb. 3, 1993 - Meeting between EPA Chief of Waste Identification
Branch, Rick Brandes, and his staff with DuPont representatives
their lawyer. EPA asked for additional information to confirm
contention that PWB manufacturers do not intentionally allow metals
into their stripper solution in order to dispose of them. EPA
indicated at the time that Federal EPA was in agreement with at
least the skins NOT being F006, but would need some time to "mend
their fences with the regions". Nothing was put into writing.
_ August 2, 1993 - letter sent to EPA by DuPont with arguments
answering questions raised at the February meeting, among them
ones showing that the metal concentration in strippers were not
being used as a method of disposal for metals.
_ December 6, 1993 - DuPont spoke to Rick Brandes by phone to
out what had been done with respect to the F006 issue. Mr. Brandes
indicated that there were still problems with some of the regional
EPAs as to their interpretation. DuPont indicated that Minnesota
had decided that both skins and sludge were NOT F006 and give
Brandes the name of the EPA official who had been sent the
_ January 24, 1994 - DuPont discussed the problem with Mr. Gregory
Helms (Chief, Characteristic Section - Waste Identification Branch)
who was standing in for Mr. Brandes at the AESF/EPA convention
Orlando. Mr. Helms indicated that Region III was still not
cooperating with Washington EPA on the interpretation. Mr. Helms
said that another follow-up letter might help.
_ February 3, 1994 - DuPont sent a follow-up letter to Mr. Brandes
- reiterating all the above, indicating that the Minnesota state
EPA had found that the material are not F006, and that the
interpretation was causing the industry an unnecessary expense
loss of competitiveness. A copy of the letters from Minnesota
Midwest Circuits Association was included.
_ March l, 1994 - We met with Mr. Brandes, but were unable to
reach a resolution of the skins issue.
Summary of States/Regions Findings on F006
Region 2 - New York State - finds resist skins and sludge are
Region 4 - Florida State - finds that skins and sludge are NOT
Region 5 - Minnesota State - finds that resist skins & sludge
NOT F006. [Midwest Circuit Association]
Region 9 - Arizona (and soon to be California) - find that resist
skins & sludge are NOT F006. [Continental Circuits Inc.] [Printed