I never for one minute considered that anyone was still building SMOTL (Solder Mask over Tin Lead) Apparently it is still common in the UK. When i said that Fused T/L was more expensive to process, I was thinking of SMOBC (Solder Mask over Bare Copper) with either selectivley plated or stripped T/L, which had a spurt of approval in the '80's. (very few shops could pull it off.)(plugged or reduced diameter holes was the killer issue). Werner, having been specialized in the HASL process for 12 years, I must say, your understanding of the process is amazingly good. TechNetters are well advised to listen activley when you speak about the process. Kudos. Related Notes: When i started with the leveling service in '78, the biggest part of the biz was re-working T/L plating. usually because of low deposits and de-wetting probs. As Werner indicated, HASl is the only finish that accuratley previews the coppers solderability. This is due to the passive nature of application. The copper must accept the metal. Also, as i may have said in the past, all that glitters is not HASL. There is a wide variety of equip. in the field. Vertical and Horizontal. Not all have the same level of control. The two primary vendors for the Horizontal process, are Halco and Cemco. Non coverage, exposed Cu after the first pass has always been an issue with SMT and i suspect this is the main reason for multiple passes. Afri hit all the right buttons when he described his efforts to minimize the problem. Maintanance is paramount to process control. There are also significant design differnces between these two above mentioned OEM's but thats another story. Sorry for the diatribe, but this is important stuff. Mark Simmons ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################