1/4 oz. is something that many shops have evaluated or may be using for "leading edge" technologies. Some difficult .004/.004" technologies may have better yields utilizing this type of thin foil. Pricing-I'm finding that the cost (at this point in time) is much higher. Availability is also an issue. Sometimes we must order large amounts to justify the "cut and tool to size" requirements. Handling is an issue. Some of it is available with a temporary carrier. (Peeled away after lamination) This is far beneficial than the loose thin foil. These foils are additionally available in 3/8 oz and 1/8 oz. Technology....hummm. I believe that with these thin foils that image and develop become the gauging factor. (eg. <.005" technology is achievable) Other issues that become apparent are AOI resolution and electrical test. (Electrical test when the parts have extremely high IO) Peel strength-You can anticipate a peel strength much less than 1/2 oz. These thin foils have very low profile topology on the treated side and naturally yield low peel strengths. Rework/pads lifting off- I don't have any idea on that question. Maybe someone else can offer more input. If you would like to discuss further information, please feel free to email me direct. [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: 1/4 oz cu Author: [log in to unmask] at SMTPLINK-HADCO Date: 12/6/95 10:20 AM We have traditionally used 1/2 oz cu in our designs and are considering 1/4 oz on some new designs (density issues). Are any of you using 1/4 oz? What min trace/clearance are you using. In rework, do the pads lift off? Any special concerns in manufacture?? Is cost greater/less than 1/2 oz? Special handling problems? Etc etc etc??? Any input would be appreciated. thanks gary ...