Charlene, The weak link when using photoimagable soldermask is the mechanical alignment of the artwork (films) and the skill of the soldermask technician. Both LPI and dryfilm soldermasks are imaged after they are applied to the PCB, therefor it is the imaging (film alignment) which is critical, not the application of the soldermask material or it's type. Larger fabrication panels and films make alignment more difficult because they suffer from greater expansion and contraction than smaller panels. It is in the fab houses best interest to use large panels because they reduce the cost of PCB manufacturing (larger panels=more PCB's per panel=less labor and less wasted materials). It may be helpful to talk to the cam operators at your fab house. Explain your soldermask clearance requirements, they may be unaware of the panel size issues (turnover is very high at most fab houses and technicians are often inexperienced). They are probably willing to work with you to achieve the best possible registration. If they won't or can't then shop around, there are fab houses that can work with 2 mil clearances (1 mil ??). Good Luck, Mark Koitmaa TechServ www.TechServInc.com ---------- From: Charlene Dwyer[SMTP:[log in to unmask]] Sent: Thursday, September 05, 1996 10:23 AM To: [log in to unmask] Subject: Soldermask-misregistration Does anyone know if there is a particular soldermask that will keep tighter registration. For instance, is a liquid soldermask able to keep a tighter registration than a dry film? Currently, we allow for a 4mil misregistration in our soldermask opening. We would like to bring that number down to 2 or 1mil on a very tight board we have (that has cooper covering the ground pads-causing the ground pads to have a larger shape) without having the manufacturer scrap alot of boards. Our plating is immersion nickel/gold. Thank-you Charlene Dwyer [log in to unmask] **************************************************************************** * The mail list is provided as a service by IPC using SmartList v3.05 * **************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * **************************************************************************** **************************************************************************** * The mail list is provided as a service by IPC using SmartList v3.05 * **************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ****************************************************************************