1998 Pollution Prevention Internship Program
Final report (Sept 10, 1998)
Reducing Ammonia Emissions
Wastewater Recycling
Ceramic Filter Evaluation
Intern:
Greg Griffin
40 Gables Way
Bin 231
Durham, NH 03824
603-862-8988
ggiffin@cisunix.unh.edu
Facilities:
HADCO Corporation
21 Flagstone Drive
Hudson, NH 03051
HADCO Corporation
7 Manchester Road
Derry, NH 03038
Contacts:
Marc Duquette
Phone: 603-896-4181
Fax:
603-896-4189
E-mail: mduquette@hadco.com
Don Kennedy
no longer with HADCO
Executive Summary
There were three major projects that I undertook at the Hudson and Derry
HADCO facilities this summer. The first was examining the possibility of reducing
Hudson's Ammonia emissions from their etching tanks using aqueous hydrochloric acid.
The second was investigating the prospect of recycling Derry's electroplating rinsewater
using ion exchange, reverse osmosis or a combination of the two technologies. The third
was evaluating the recycling of stripper solution in Derry's multilayer stripping line using
a ceramic filter.
Introduction/Background
Both the Hudson and Derry HADCO facilities have DES lines. Each line
consists of a developer, an etcher and a stripper. In the developer, the exposed core is
passed through a chemical solution removing the resist from areas not polymerized. In
the etcher, Copper is chemically removed from the core in all areas not covered by film
resist. In the stripper, the remaining dry film resist is now chemically removed form the
panel, leaving copper only in the patterns described by the artwork.
HADCO at Hudson uses a high Ammonia etch in the etching process of their DES
line. In the past, etch rates on baths have been reduced in order to decrease the amount of
waste etch generated and therefore the amount of gaseous Ammonia emitted. It is
probable that the injection of aqueous hydrochloric acid into the process could reduce
these emissions further.
Both de-ionized and city water is used in the PCB industry to rinse surface
contaminants from boards being plated. The flow rates of rinse water in the
electroplating lines at Derry have already been evaluated and minimized accordingly.
Since there is a cap on the amount of water that the facility can use, recycling rinse water
will reduce cost as well as allow for expansion. HADCO has also informed the town of
Derry that they would be looking into a project of this nature.
The addition of a ceramic filter to Derry's multilayer stripping process could
theoretically recycle 90% of the working solution, greatly reducing the need for fresh
chemistry.
Goals/Objectives
The Hudson objective is to reduce gaseous Ammonia emissions at their source
using an aqueous solution of 5 M PC grade hydrochloric (muriatic) acid. The Derry
objective is to examine ways that wastewater may be recycled from electroplating rinse
tanks using ion exchange, reverse osmosis or a combination of the two technologies. As
you probably already know ion-exchange uses electrical current to remove metal
impurities and reverse osmosis involves forcing water through a semi-permeable
membrane. Proposals from Kinetico and U.S. Filter are being considered. Derry's
secondary objective is to evaluate the performance of the ceramic filter on the multilayer
stripping line to determine whether it is compatible with the process. The ceramic filter
operates analogous to a conventional filter except the flow of permeate is tangential and
as the filter is a porous ceramic medium it won't foul or tear.
Approach/Methodology
The first step in reducing the Ammonia emissions in Hudson is to profile the
production line and determine how much Ammonia is normally emitted. Then, the
change in the amount of Ammonia emitted as hydrochloric acid is added can be
monitored.
In order to recycle wastewater from electroplating tanks at Derry, resistivity
measurements must be taken to find out which rinse waters are compatible with each of
the proposed recycling systems. Currently systems from Kinetico and U.S. Filter are
being investigated.
Once the ceramic filter has been hooked up to the multilayer stripping line,
suspended solid and hydroxide concentration measurements can be taken to determine
how well the system is operating.
Chemical Usage, Equipment Needs
The first project will cause an increase in the amount of hydrochloric acid usage at
Hudson and will require a system of delivering the acid to the line. The second project
will require extensive new equipment but no new chemical usage will result. HADCO is
in possession of a pilot PhoenAnkh ceramic filter that can easily be applied to the
stripping line.
Releases/Wastes Generated At the Facility
The addition of hydrochloric acid to the etching line generates a non-hazardous
waste. As far as the other two projects, no new waste or releases should be generated.
Details Of Work Accomplished/Project Results
With the exception of the stripper data, the data collected doesn't lends itself to
graphical representation.
At Hudson, baseline emission readings were taken on line 1. It was later
determined, however, that these numbers were not very meaningful as the quantity of
product going through the line was not monitored while the measurements were taken.
When the project is continued this fall, a more thorough and comprehensive emission
baseline will be realized.
As a result of this oversight of sorts, there is no way to tell how much the addition
of the hydrochloric acid reduced ammonia emissions. The trial itself, however, was
promising in that the etcher seemed to operate normally for the duration and no
complications were caused by the addition of the acid. Data obtained from the trial can
be found on page i. The only complication was that water started getting into the etch
chamber midday on the second day of the trial. This undoubtedly led to some erroneous
data.
At Derry, resistivity measurements were made in all water containing rinse tanks.
This information was used to determine which tanks were compatible with the proposed
rinsewater recycling system (this information can be found on pages ii-vi). For the most
part, it would be possible to recycle all but the scanning spray rinses. I can't say much
about the proposed system itself as this information is proprietary. Those of you reading
this in the field will no doubt have access to Kinetico's proposal.
Also at Derry, the ceramic filter was in operation for a little over a week. A
diagram of this system can be found on page vii. The hydroxide concentration and TSS
of both the permeate, the filtered chemistry returned to the process, and the stripper bath,
the spent solution fed to the filter, can be found on page viii-xii. The hydroxide
concentration in both the permeate and the stripper bath seemed to reach a steady state
towards the end. The permeate TSS stayed low and more or less constant. There is a lot
of variability among the TSS data of the stripper bath as samples were taken from the
stripper itself rather that the 300 gallon supply tank where the solids were actually being
concentrated.
Pollution Prevention Benefits
None of these projects is a pollution prevention technique. Using a low Ammonia
etchant in the etcher, decreasing the flow rate of rinse water in the electroplating tanks
further or using a different chemistry in the stripper are not options. These projects are
therefore the next best environmental option.
Recommendations for Future Efforts
A meeting was held on July 9 to determine the status of the ammonia emissions
reduction project. It was decided that the line 2 would more easily lend itself to this type
of evaluation when it returns to the facility in the fall. The proposed time line appears
below:
Action
Install line #2
System check/debugging
Release line to production
Baseline study
Begin HCl trial
Issue report
Completion Date
September 7
September 28
October 1
October 15
October 18
October 28
Kinetico is the most promising of the rinsewater recycling systems.
The ceramic filter results look good. A more in depth analysis, however, might be
in order before units are purchased and become permanent fixtures.
Appendices
William S. Banham
Kinetico Incorporated
10845 Kinsman Road
P.O. Box 127
Newbury, OH 44065
Phone: 800-633-5530
Fax: 440-338-8694
Thomas G. Ieronimo
Box 578
17 West Meadows Road
Watertown, CT 06795
Phone: 860-945-6004
Fax: 860-945-6197
Rich E. McCarthy
Dexter
Phone: 800-877-9871 ext. 260
Rick Morgan
Nationwide Circuit Products
15 Colonial Drive
East Hamstead, NH 03826
Phone: 603-329-6983
Fax: 603-329-4021
Dean Schmelter
Water Specialists LLC
P.O. Box O
West Suffield, CT 06093
Phone: 860-668-9779
Fax: 860-668-0660
Janet Torrant
Water Specialists LLC
P.O. Box O
West Suffield, CT 06093
Phone: 860-668-9779
Fax: 860-668-0660