If you or your kids have played with lizards, you may have witnessed their interesting ability to regenerate a tail-for later use in that special etchant mix. For example, the addition of ammonium chloride, monomethanol amine, ethanol, acetonitrile, acetone, or dimethylformamide to cupric chloride produces a better etching rate and increases the amount of dissolved copper. In addition to the etchant, many manufacturers supplement etchants with chemical additives to achieve better etching characteristics. Table one compares the impact of three well-known etching materials. After all, none of would appreciate the extra added flavor of waste etchant in our morning tea or the sensation of etchant mixed with our shower soap. Manufacturers invest significant resources to comply with federal and state regulations that govern liquid wastes. Now that we’ve taken a walk on the wild side, let’s think about the economic and environmental impact. Those processes include the addition of other chemicals that react with soluble pollutants, filtration that removes sludge, reverse osmosis, ion exchange, membrane filtration, and different types of rinsing techniques. Manufacturers use different stages of treatment to recover and reuse the water. Most of the materials that make up the waste streams consist of suspended solids, metals, fluoride, phosphorus, cyanide, and chelating agents. The waste streams from the PCB production processes include spent etchant and waste rinse water that includes ammonia, chromium, copper, iron, and acids. So…why create this list and why care? After all, the etchants work and we have jobs. Before that, many manufacturers used ferric chloride as an etchant liquid.
In terms of etching capabilities, the use of those chemicals has worked well as part of the subtractive method for producing PCBs. We can cut the list to include the two most-used types of etchants: ammoniacal etchant and cupric chloride. A Witch’s Brew: PCB Manufacturing and EtchantsĪt one time or another, PCB manufacturing processes use solvents such as ferric chloride, cupric chloride, ammoniacal etchant, sulfuric acid + hydrogen peroxide, sulphuric and chromic acid, cupric chloride, alkaline etching, and copper ammonia complex ion as etching fluids. However, the poisoned entrails, eye of newt, toe of frog, and lizard tails that go swirling into the cauldron are actually the ingredients for old-style PCB etchant.īut…we may want to stifle our gasps just for a minute while learning about the new wave-not wave solder-of environmental PCBs. If we didn’t know better, we might conclude that the preceding lines are from some type of Shakespearean-like play or something.
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