In regard to tenting vias. Several years ago we asked ourselves why we tented. The answers were : ICT Design. We solved the ICT reason by going to mechanical fixtures instead of vacuum. Or by the use of a lidded fixture. Design (turned out to be a imagination item) because it was not required as at the same time we were minimizing the use of flow solder process and going to two reflow processes. As it turned out, with attention to the wave process, there was not a need to tent in wave either.... You need to look at your processes in assembly and see if you have a real need! [log in to unmask] ---------- From: TechNet-request To: technet Subject: LPI Soldermask with Tented Via's Date: Friday, June 09, 1995 6:28PM As a manufacturer of high-rel and Mil Printed Circuits, we have seen an increasing number of board designs that require the use of (LPI)Liquid Photo Imageable soldermask. The LPI masks perform well in most cases, but many of these designs incorporate tented via's. In the past, Dryfilm soldermasks have been used for boards with tented via's, but many customers are moving away from the dryfilm soldermask. We are currently using a "via fill" process in which we fill the holes with an epoxy s/m by screen printing. This is followed by application of the Liquid Photo Imageable (LPI) soldermask over the surface of the board. The result is an LPI mask with tented via's. To me, this process seems to be a step backward on the technology curve. It requires more process steps and more time. We would like to get away from the screen printing and pursue a 100% Photo process. I have discussed this issue with several soldermask suppliers, and I have been told that this is a very common procedure and that many other board shops use the same process. None of our suppliers have offered a more effective solution. I would be interested in any feedback related to the use of LPI soldermask when tented via's are required. Would anyone like to share their "success" stories or recommend a supplier that could help with this issue. Thank you in advance for your comments. Sincerely, Jim McNeal ===================================================== Jim McNeal Q.A.and Eng. Mgr. Electro Plate Circuitry, Inc. Carrollton, Tx Ph. 214-466-0818 EMAIL [log in to unmask]