Thanx Brian. Reminds me.....I used to carry around squares of Kleenex that had been roller tinned. They looked just like a piece of tinned copper right up till you poked them with a soldering iron. Saved hours of discussion about solderability. Regards Mike Fenner Applications Engineer, European Operations Indium Corporation T: + 44 1908 580 400 M: + 44 7810 526 317 F: + 44 1908 580 411 E: [log in to unmask] W: www.indium.com Leadfree: www.Pb-Free.com -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Brian Ellis Sent: Tuesday, March 25, 2003 8:27 AM To: [log in to unmask] Subject: Re: [TN] Roller Tinned PCB's Mike The others have not really answered what roller tinning is. Imagine a trough of molten solder, in which an iron drum is rotated with a peripheral speed of about 10 or 15 cm/s. On top of the iron drum is a heat-resistant "rubber" roller. The drum is tinned with the solder, with the aid of an active water-soluble flux. The PCBs are dipped into the same flux and fed between the drum and the roller, copper side down. This transfers some of the tinning onto the copper. This is the basis of roller tinning. The thickness of the tinning is microscopic and is really only the intermetallic layer with an admixture of iron, except that a blip of thicker solder is left on the trailing edge of each conductor (much worse than the uneveness of HASL). It was used for both single and double (2 passages) sided circuits before plating-through of holes was common, often the holes equipped afterwards with some form of rivet. Obviously, it was useless with PTHs, because there was insufficient tinning on the drum to enter the holes: this was the real cause for its demise. The quality of protection was fairly mediocre, solderability being maintained for only 2 or 3 months, because of the thinness of the coating. Notwithstanding, it was a very popular, cheap, coating in its heyday. It was not replaced by HASL, which came later, but by tin-lead plated boards initially, followed later by hot-oil and then infra-red fusion. About the same timeas the late days of roller tinning was the forerunner of HASL, the Hydrosqueegee. This called for passing the bare boards over a solder wave and then immersing them in a violent spray of hot oil to level off the excess and clear the holes, even PTH. This was not very popular because the smell was atrocious and the machines were a fire hazard. Brian Michael Bell wrote: > Hi all, > > Just a little stumped on terminology here, what is "Roller Tinning". What > is the specific differences between this method and HASL??? Are there any > specific pros/cons for the Roller method??? Any information would be > appreciated. > > Cheers > > Mike > > --------------------------------------------------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8e > 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/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 > ----------------------------------------------------- > > > --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/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 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/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 -----------------------------------------------------