Kokomo, IN, USA
ESD gloves and finger cots are found at nearly every electronic manufacturing facility at assembly, rework, and repair stations, worldwide. The reason for using hand coverings is twofold: to reduce the risk of transferring detrimental skin oils and salts to the PCBA; to reduce the risk of electrical shock due to static electricity buildup from clothing and the environment. There are many different glove material types, having different advantages, as well as disadvantages. Some gloves and cots are treated with powders or chemicals to help the user fit or tactile feel; however, these can be transferred to the PCBA. The transferred materials may be detrimental to the PCBA by setting up electrical leakage and/or electrochemical migration-related issues in normal field service environments. This study will look at the possible glove related effects in normal use of introducing known contamination, using ion chromatography.
Choosing a protective glove for the production floor is a critical decision and all variable need to be considered. If ESD is not a special consideration, for PCB manufacturing, then all you need to consider is cleanliness as salts and oils can induce an insulative barrier that may inhibit proper solder flow. If they are to be used in an assembly house there needs to be a balance between ESD protection and cleanliness. The results of this study suggest that overall the vinyl gloves have the least total amount of ionic content. All three are at a low risk of introducing enough ontamination to facilitate electrical leakage and/or electrochemical migration. The study was a worst case scenario with repeated exposure of various gloves to a single area. In normal production the risk for causing detrimental damage comes from handling of chemistries and then handling assemblies. When process chemistries come into contact with gloves it takes very little to transfer those residues to the surface of an assembly. The IPC-A-610F  states in 3.3.1 "Touch only the edges away from any edge connector tabs. Where a firm grip on the board is required due to any mechanical assembly procedure, gloves meeting EOS/ESD requirements may be required. These principles are especially critical when no-clean processes are employed" This should always be part of any employee training for handling of PCBs/PCBAs. One best practice is to train employees to properly handle the samples as if they were not going to be wearing gloves, and then wear gloves. Handling is a very real threat to the cleanliness and reliability but it isn't from the glove itself but more likely the manner in which they are being worn.
Initially Published in the SMTA Proceedings