Fact Sheet: Printed Circuit Board Manufacturers

Virginia Waste Minimization Program
Vol. 1 Issue 9

A Fact Sheet from the Virginia Waste Minimization Program: Printed Circuit Board Manufacturers

Background

The Printed Circuit (PC) Board Manufacturing industry generates a variety of production wastes. Reducing this waste generation can decrease your future liabilities, make regulatory compliance easier, and reduce your disposal costs. thus saving you money.

Typical wastes generated by the PC board industry are:

• Industrial wastewater and treatment residues
  
• Spent process baths
  
• e/acids used for cleaning equipment
  
• Copper sulfate crystals
  
• Re-flow oil.

Waste Reduction

Waste reduction can reduce the amount of hazardous wastes generated in your shop. A waste reduction program benefits you by minimizing:

• Disposal costs
  
• Regulatory compliance costs (e.g.. recordkeeping, reporting, tracking, etc.)
  
• Current operating costs (i.e., raw material costs, etc.)
  
• Transportation costs
  
• Off-site treatment costs
  
• Worker safety costs.

The Uniform Hazardous Waste Manifest requires large quantity generators to certify that they 'have a program in place to reduce the volume and toxicity of waste generated... [as) determined to be economically practicable' and have selected the [most] practicable method of treatment, storage, or disposal currently available ... [that] minimizes the present and future threat to human health and the environment.' Small quantity generators must certify that they have made a 'good faith effort to minimize waste generation" and have selected the best affordable waste management method available.

Since waste reduction methods reduce the amount of waste generated as well as the amount subject to regulation, these practices can help a shop to comply with the requirements and to save money. The following list details some common waste reduction methods for PC board manufacturing shops, including source reduction, recycling and resource recovery and treatment alternatives.

Begin at the Top

The shop's owner or manager must be committed to waste reduction and must pass that commitment on to the employees.

Training should be established for employees in waste reduction. hazardous material handling and emergency response.

Incentive programs should be formed to encourage employees to design and use new waste reduction ideas.

Assess Hazardous Waste

Waste assessments are used to list the sources, types and amounts of hazardous waste generated to make it easier to pinpoint where wastes may be reduced.

Source Reduction

Some source reduction opportunities are the least costly approaches to minimizing waste. Many of these involve housekeeping changes or minor in-plant process modifications.

Improve Procedures and Segregate Wastes

• Keep work areas clean. Good housekeeping is the easiest and often the cheapest way to reduce waste.
  
• Designate protected raw material and hazardous waste storage areas with spill containment. Keep the areas clean and organized, and give one person the responsibility for maintaining the areas.
  
• Label containers as required. and cover them to prevent contact with rainfall and to avoid spills.
  
• Use a "first-in, first-out" policy for raw materials to keep them from becoming too old to be used. Give one person the responsibility for maintaining and distributing raw materials.
  
• Segregate waste streams for recycling and treatment and keep non-hazardous material from becoming contaminated.
  
• Prevent and contain spills and leaks by installing drip trays and splash guards around processing equipment.
  
• Routinely inspect tanks and tank liners to avoid failures.
  
• Use dry cleanup wherever possible to reduce the volume of wastewater.
  
• Tom off rinse tanks when not in use.

Material Substitution

• Use materials that reduce sludge generation or are easy to recycle.
  
• Use de-ionized water instead of tap water in process baths and/or rinsing operations to reduce sludge volume.
  
• Use non-chelated rather than chelated process chemistries to reduce sludge volume.
  
• Try using mild chelators if chelators are required in the process.
  
• Use alkaline cleaners instead of solvents for degreasing operations. These cleaners may be treated on-site and may usually be discharged to the local sewer with permit authorization.

Extending Process Bath Life

• Treatment (e.g., filtration, electrolytic dummying, etc.) of process baths can extend their useful lives.
  
• Bath replenishment extends the useful life of the bath.
  
• Monitoring the baths (using pH meters or conductivity meters) can determine the need for bath replenishment.

Drag-Out Reduction

• Minimize bath concentrations to the lower end of their operating range.
  
• Maximize bath operating temperatures to lower the solution's viscosity.
  
• Use wetting agents which reduce the surface tension of the solution in process baths to decrease the amount of drag-out.
  
• Withdraw work pieces from tanks slowly to allow maximum drainage back into process tanks.
  
• Use air knives or spray rinses above process tanks to rinse excess solution off of work piece and into process bath.
  
• Install drainage boards between process tanks and rinse tanks to route drag-out back into process tank.
  
• Use dedicated drag-out tanks after process baths to capture drag-out.
  
• Install rails above process tanks to hang work piece racks for drainage prior to rinsing.

Rinse Systems

• Use air agitation or work piece agitation to improve rinse efficiency.
  
• Install multiple rinse tanks (including counterflow rinse tanks) after process baths to improve rinse efficiency and reduce water consumption.
  
• Installation of flow controls can improve rinsing efficiency and reduce wastewater volume generated by rinsing operations.

Equipment Cleaning

Use a multistage cleaning line for work piece racks similar to a multistage rinse system. This will reduce your waste cleaning solutions.

Recycling and Resource Recovery

• Reuse the acid rinse effluent as influent for the alkaline rinse tank. This allows the fresh water feed to the alkaline rise tank to be turned off (reactive rinsing). This can also be applied to process tank rinses.
  
• Treat rinse water effluent to recover process bath chemicals. This allows the reuse of the effluent for rinsing, or neutralization prior to discharge.
  
• Spent process baths include strong and mild etchants and alkaline photoresist stripper. These baths can be regenerated to recycle valuable etchants.
  
• Use treatment technologies to recover metal and metal salts from process baths.
  
• Reuse the spent reagents from the process baths in the wastewater treatment process.
  
• Recycle spent solvents on-site or off-site.
  
• Use treatment technologies to recycle rinse waters in a closed loop or open loop system.
  
• Some recycling and most treatment processes require a permit. Be sure to contact the Department of Waste Management to determine if you need a permit to treat or recycle your wastes.

Treatment Alternatives

• Pre-treat process water to reduce the natural contaminants which contribute to the sludge volume.
  
• Use treatment chemicals that reduce sludge generation (e.g., caustic soda instead of lime).
  
• Use sludge dewatering equipment to reduce sludge volume.
  
• Use treatment technologies (such as ion exchange) that do not use standard precipitation/clarification methods which generate heavy metal sludges.

(This information was reprinted with permission from the California Department of Health Services, Toxic Substances Control Program, Alternative Technology Section. Modifications have been made to tailor this factsheet for use in Virginia.)

This Waste Reduction Fact Sheet is provided as a service of the Virginia Waste Minimization Program, a technical assistance program of the Virginia Department of Waste Management.

For more information on opportunities to reduce waste contact:

Virginia Waste Organization Program
11th Floor Monroe Building, 101 North 14th Street
Richmond, Virginia 23219
804-371-8716 or 1-800-552-2075
TDD 804-371-8737