Fine Lines in High Yield (Part CLXXXI)

摘要

Many users of aqueous photoresists have experienced the accumulation of solids in the acid etching equipment. These solids are usually greenish-black in color and tar-like in consistency. Analyses have identified these residues as predominantly organic, consisting of photoresist components and antifoam ingredients, such as poly-glycols that are added to the developer for foam control. These organic residues are not specific to a particular type of aqueous dry film photoresist or liquid photoresist.The etcher residue, often referred to as "goo" because of its tarry consistency, builds up over time and collects on the etcher walls near the surface of the etcher liquid level, and it is very difficult to remove. This residue also can enter the etcher spray system and deposit on conveyor wheels and panel guides. From there, it can redeposit on panel surfaces, acting as etch resist and causing excess copper and short defects on inner-layers.