Thanks everyone for your help. The article at www.circuitree.com "Copper Plating of Electronic Interconnects without Additives" was very helpful indeed. By "additives" they are referring to brighteners and levelers. The bath they described contained polyethylene glycol. This article lead me to find two more lnks. http://www.pcfab.com/db_area/archive/2001/0103/taylor.html And US patent 6,303,014, which describes the "additive free" process in greater detail. However, they also use a "supressor", such as polyethelene glycol in combination with the chloride ion. http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1 &u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1='6,303,014'.WKU.&OS=PN/6,303,014&RS =PN/6,303,014 In reply to Rudy Sedlak, I beginning to see that the rectifier cannot be a total solution. Adam Seychell --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------