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20 PCB007 MAGAZINE I FEBRUARY 2023 stream processes. ese rinse waters become contaminated with wet processing chemicals and need to be treated before disposal. is is something that you can do in-house, but how you do it may depend on the wastewater regula- tions in your area. You may be required to precip- itate any heavy metals out of the water to make it meet your discharge permit limits. In this case, the precipitated metal sludge is another waste steam that will need to be handled. Typically, this sludge is filtered off from the water, dried, drummed, and sent off to a waste treatment facility. Excess etchant is another waste product you need to plan for. As you etch your PCBs and make chemistry adjustments, you will accumulate etchant in your etching machine over time. is excess etchant needs to be pumped out before the level gets too high in your etcher bath. Since the excess etchant usu- ally doesn't meet quality requirements for reuse, and because it is concentrated, it is com- mon practice to pump the excess etchant into a barrel that will get shipped to a waste treat- ment facility. Conclusion If you are looking for a good place to start planning your PCB fabrication process, I hope the information I've provided here gives you a better idea of what to expect. Knowing about these matters and preparing for them ahead of time can make planning your wet process— and your job—much easier. PCB007 Christopher Bonsell is a chemical process engineer at Chemcut. To read past columns, click here. Available Workspace As I mentioned, the floor space require- ments of your equipment should be a major consideration when planning your facility. When deciding on the equipment you will need to meet production goals, you must find a balance between available floor space and how to meet your production needs. When working on the layout of your facility, keep in mind that you'll need to reserve addi- tional space to ensure that people can easily run and maintain your equipment. Poor manu- facturing floor design can create inconvenient situations for operation and maintenance, which can negatively impact the longev- ity and efficiency of your equipment. Having an awareness of space is vital when planning your process because you need a layout that will get your equipment inside the facility and leave enough space for it to be operated efficiently. Process Locations When planning out your wet process, you may want to consider its location relative to other equipment. is is because corrosion is a given with etching equipment. Although the equipment safely contains the etching chem- icals, the process tends to create a corrosive environment; anything metal in the area that lacks some form of corrosion resistance will experience corrosion over time. Etching equip- ment is oen kept in its own room to account for this phenomenon. erefore, if you have an expensive machine testing your printed circuit boards, you do not want it in the same room as your etching machine. Waste Management Producing PCBs generates many different forms of waste. For wet processing, contam- inated rinse water and excess etchant are common waste streams. As you process a panel through one of the wet processes, it's normal to rinse it before it goes to the down-