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AUGUST 2024 I PCB007 MAGAZINE 39 agents, this method does not yield quantitative results. With the real-time analyzer, it is pos- sible to measure the organic addition effects accurately and within a short time. is pro- vides data in real-time and allows the opera- tors and engineers to quickly make necessary adjustments in chemistry while maintaining a very tight process control window. When the key organic addition agents are maintained within a narrow operating window, there will be minimal variation in the physical properties of the copper deposit. is cannot be over-emphasized. Rinsing Another oen overlooked process is rinsing. PCB fabrication wet processes require good quality rinse water and the implementation of best practices with respect to proper rinsing design. Here again, is the quest to reduce cost by cutting back on rinsing. is is not an ideal situation. It is a hard fact that processing printed cir- cuit boards consumes large volumes of water, a precious resource. However, there are ways to perform the function of removing contam- inants from the printed circuit board and still conserve water. Rinsing is oen defined as the removal of pro- cess solution from the panel. is is mostly true, if not absolutely true. Rinsing, in general, is not the complete removal of the contaminants, but rather a dilution of a process solution from the work (panel) down to "manageable" concentra- tions. With this definition in mind, rinsing sys- tems can be designed to minimize harmful con- taminants on a printed circuit board and reduce water consumption. I'm oen asked whether there is some "standard" that can be applied to the rinsing process. Are all types of contami- nants the same? Is there a hard and fast rule for rinsing? e short answer is, not really. What constitutes a "manageable" concentration is dependent upon three conditions: • e type of contaminant • e tolerance of the following process step for the particular contaminant in question • e effect the residual contaminants have on the work e bottom line is to use tempered water rinses along with sufficient dwell times required to remove the majority of these harmful con- taminants. Counterflow rinses are particularly effective. When rinsing is ineffective (Figure 3), the stark reality of contaminant drag-in to subse- quent process steps is certain. Figure 2: Note cracking of the plated copper due to organic addition agent imbalance. Figure 3: Poor rinsing leads to cleaner drag-in to another key process tank, showing significant foam from residual cleaner drag-in.