Many concerns come to mind with this lead length criteria. I assume that you are talking about components that will be hand inserted into a plated thru hole. The accepted norm in the past for all my applications has been a max of 0.100" Longer lead lengths mean that: --Spacing between the leads will have to be increased because there will be a greater tendency for the leads to short together during the wave solder process. --Your solder pot clearance will have to be adjusted for the lead length, and as a result will have to throw a higher wave to contact the PCB, possibly resulting in wave solder defects(skips) if not maintained properly. If you are not using a nitrogen system, this will result in an increased amount of dross. --There is a greater tendency for the leads to be bent in normal handling and could short to each other if they get bent. --Consider the product design and how it fits in the package. I recommend that you set a criteria of 0.060" +/- 0.030" for lead length. This is an accepted standard and has been successful for years. E. Holton [log in to unmask] ------------- Original Text From: C=US/A=INTERNET/DDA=ID/TechNet-request(a)ipc.ipc.org, on 11/15/96 5:59 PM: Greetings Technetters- In the interest of streamlining a process, we're experimenting with straight-thru assembly of leaded components in mixed-tech products. The proposal on the table is to allow protrusion of up to 3.6mm (0.15"). This doesn't conform to existing IPC requirements (we're building Class 2 products). What should be our concerns, other than potential shorts? Why is Class 3 so stringent at 1.5mm max? Thanks for your help. *************************************************************************** * TechNet 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. * *************************************************************************** 0 *************************************************************************** * TechNet 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. * ***************************************************************************