>-----Original Message----- >[mailto:[EMAIL PROTECTED] On Behalf Of Jon Elson >Sent: Tuesday, January 11, 2005 1:54 PM >Subject: Re: [PEDA] Tenting > >> >>From: Dennis Saputelli [mailto:[EMAIL PROTECTED] >>i recently sent a board to a new shop for us >>the notes said 'tent smallest vias' >> >>they called and said they can't tent the vias unless they use >dry film, ... >> >> >Well, I think it is more than terminology. The dry film >soldermask goes on as a sheet of material thermally laminated >to the board. It is quite thick, and will remain as a planar >sheet, covering holes up to maybe 1/8" diameter without >sagging into the hole. > >The LPI is a thick liquid squeegeed onto the board. It may >fill in the holes, or sag down and then pop, coating the hole >walls partially. The very smallest vias might actually get >tented pretty well as the stuff goes on. But, then when it is >exposed and developed, the LPI in the holes may not harden, >and it will then get washed away during the development step. >You've got to trust the fab shop, as they know their processes >and materials better than anybody.
That's something good to know. I've always just trusted the fab shops to acomplish the task outlined by the gerbers and never stopped to think about the process used...I've been lucky so far, in that I've seen little in the way of LPI-realted problems, but I wouldn't want to get caught with my proverbial pants down by some future project where it really mattered! Thanks for the explanation. It could come in quite handy in the future. aj ____________________________________________________________ You are subscribed to the PEDA discussion forum To Post messages: mailto:[email protected] Unsubscribe and Other Options: http://techservinc.com/mailman/listinfo/peda_techservinc.com Browse or Search Old Archives (2001-2004): http://www.mail-archive.com/[email protected] Browse or Search Current Archives (2004-Current): http://www.mail-archive.com/[email protected]
