Hi Daan, just looked at our data. We use openings with 1.27 (50mil) diameter for 0,3mm finished hole size vias. The boards are 233mmx 160mm. Sounds a bit large ? I thought that we aimed at 1-1,1mm. But thatīs our newest design I opened. The explanation from our CAD guys is that this has been checked with our favorite boardhouses to meet their tolerance specs and to be on the safe side of life. This is not based on any IPC or other document, just our practice to prevent problems. I canīt tell you wich diameter will do with no problems but usually the boardhouse is gonna give us a call if something within our data calls for problems and ask if they are allowed to change it to meet their requirements. For new jobs we usually intergrate those new dimensions in our CAD if there is no problem with other technical requirements. Your spacing doesnīt allow for much tolerance and you have to consider that you have to drill a bit larger to get 0,3mm finished diameter. If your boardhouse didnīt give you a call although they expected trouble I would place their name on a different supplier list. Best to you Wolfgang -----Ursprüngliche Nachricht----- Von: d. terstegge [mailto:[log in to unmask]] Gesendet am: Freitag, 27. Juli 2001 10:37 An: [log in to unmask] Betreff: [TN] Clearance area around holes Hi Technet, Here's a question for the bare board experts out there: One of our pcb-suppliers had rejects on a complete batch of our boards because the clearance between the via's and the surrounding copperplane was so small that it resulted in short circuits. The holes were designed 0.3 mm (finished hole size) and the openings in the copperplane were 0.6 mm, leaving only a small clearance area. The board measures about 20*15 cm. What do you think, is a board like this manufacturable for a decent board shop, or is it really that difficult? Could you give me a typical value for the minimum clearance around the finished-hole that board vendors need ? Best regards, Daan Terstegge SMT Centre Thales Communications Unclassified mail Personal Website: http://www.smtinfo.net ---------------------------------------------------------------------------- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------------