How On-Site Acid Neutralization Systems Provide Safe Chemical Disposal

How On-Site Acid Neutralization Systems Provide Safe Chemical DisposalWhen the right acid neutralization system is chosen, it can automatically add the required neutralizing chemicals to acid waste left over after a semiconductor manufacturing process step. Ideally such a system should use the least amount of chemicals while ensuring adequate neutralization of waste to comply with environmental standards. The system has to have enough capacity to handle the waste chemical flow and it must operate reliably, protecting against spills and documenting chemical use and discharge. With overall environmental standards tightening and local regulations becoming more stringent, semiconductor manufacturers need acid neutralization systems that provide safe and reliable disposal of chemical waste.

How to Choose Continuous Flow or Batch Acid Neutralization Systems

Acid neutralization systems can operate on a continuous basis or can neutralize individual batches of waste chemicals. For mass production of semiconductor parts, fabrication lines operate over extended periods, using fixed amounts of chemicals and producing uniform quantities of waste.

For these large-scale operations, a continuous flow acid neutralization system is the best choice. Because the nature of the waste chemicals is known and remains consistent over time, the neutralization process can add fixed amounts of low-pH chemicals to continuously neutralize the waste flow. Neutralization can be fine-tuned because the overall process doesn’t change.

Batch neutralization systems are better suited for the production of small quantities of semiconductor products. Typical applications are prototype production, production of small quantities for testing or the manufacture of special components. For these operations, the waste chemicals have to be neutralized in small volumes and each process is different. The batch acid neutralization system has to measure the pH of the waste chemicals, and determine what low-pH additions are appropriate. The neutralization is different for each batch as is each outflow.

Automation Can Play a Key Role in Effective Acid Neutralization Systems

Automated acid neutralization systems can help reduce chemical use, ensure regulatory compliance and reduce spills. The system automatically adds the required chemicals to the waste solution, tracks chemical use, measures outflow pH and records the results. Workplace safety is increased and human error is reduced. The records of chemical use and outflow pH can demonstrate that environmental standards are met.

Automating continuous flow systems is comparatively easy because the process parameters are known and they don’t change. The complete automation of batch neutralization systems can be challenging because key variables as well as the chemicals involved can vary from batch to batch.

For a continuous flow chemical acid neutralization system, the acid to be neutralized and the low-pH chemical to be used are known. The automation only has to add the required amount of neutralizing chemical on a continuous basis and record the resultant pH. For slight variations, a control loop can adjust the amount of neutralizing chemical to achieve the required output pH.

A fully automated batch neutralization system first has to measure the batch pH and add an amount of low-pH neutralizer. Depending on the chemicals involved, the automated system may have to add different neutralizing chemicals in several stages to achieve the required output. The automated system is complicated to program and difficult to set up. For batch neutralization systems, operator involvement to select the type of neutralization required can simplify the operation of the automated system and make it more effective.

Modutek Can Help Select the Right Acid Neutralization System

Modutek has a full line of chemical handling equipment, including acid neutralization systems. The company works closely with customers to determine their needs and can customize systems to meet special requirements. Once delivered, Modutek makes sure that the acid neutralization systems operate as specified and customers are completely satisfied. Contact Modutek for a free consultation to discuss the chemical disposal requirements needed at your facility.

Choosing an Acid Neutralization System to Safely Handle Chemical Disposal

Choosing an Acid Neutralization System to Safely Handle Chemical DisposalWet process semiconductor manufacturing lines use aggressive chemicals to clean and etch silicon wafers. When a cleaning or etching step is complete, the remaining chemicals have to be disposed of safely. Low pH acids such as hydrochloric acid have to be neutralized with high pH chemicals so that the pH of the mixture approaches the neutral value of seven. The acid neutralization can be carried out continuously or in batches and either process can be fully automated. Ideally an acid neutralization system acts reliably with a minimum of supervision and keeps records of chemical use and discharge to demonstrate compliance with environmental regulations.

Continuous Flow and Batch Neutralization Systems Fulfill Different Requirements

The choice of an acid neutralization system reflects the type of semiconductor manufacturing that takes place. Large scale continuous manufacturing lines produce a continuous flow of waste chemicals. The composition of the flow and its volume changes little and can be analyzed in detail. A continuous flow acid neutralization system can then be designed to automatically and reliably neutralize the out flow. Because small changes can easily be detected and the dosages of neutralizing chemicals can be automatically adjusted, the automation required for such a system is easily set up. The automated continuous flow acid neutralization system can keep records of its neutralization activity and the volume and pH of the waste flow.

The neutralization of waste chemicals used in batch manufacturing is usually more complicated. Batch manufacturing is used for prototypes, one-of-a-king components and small quantities of special parts. Each batch can be different and it makes sense to use a batch acid neutralization system for these processes.

Instead of adjusting chemical dosages of an established process as in the continuous flow systems, batch neutralization systems have to measure the pH of the waste chemicals and add specific neutralizers. Several stages of neutralization may be required before the discharge is acceptable. Once the neutralization process is finalized, the sequence can be fully automated and can run as the batch is processed.

Other Considerations When Choosing an Acid Neutralization System

Once the choice of continuous flow or batch system is made, the acid neutralization system has to fulfill a few basic requirements. The system capacity has to be sufficient for the proposed application, with capacities ranging from a few gallons to hundreds of gallons per minute. The system can be located indoors if there is space but it can also be designed for outdoor operation. If automated, the exact automatic functions have to be programmed and set up. Finally the monitoring and record-keeping functions have to be determined.

Operational characteristics have to be considered as well. If the system is fully automated, it may run without supervision but alarms will be required for situations such as low chemical supply or a pH level outside permissible limits. Recording of neutralization process parameters can be digital, with a log, or on a chart recorder. Containment of spills is important and depends on whether the installation is indoors or outdoors. Spill detection has to be incorporated into the alarm system and the whole operation has to comply with environmental regulations.

Modutek Can Supply Acid Neutralization Systems to Meet Customer Needs

Included in Modutek’s complete line of wet process equipment are compact acid neutralization systems that can be customized to meet specific needs. Systems can be designed to fit into the space available at a customer’s facility and Modutek can help select suitable automation and operating characteristics. The Modutek acid neutralization systems operate reliably to keep waste discharge parameters close to specified values and a digital chart recorder documents compliance with discharge regulations.