The electronics companies who swear by DOE and Taguchi arrays are many. There's the classic example of the Wave solder matrix, two types of flux, two pre heat settings, two conveyor speeds and two bath temperatures. The wonders of this experimental method are praised through out the electronics manufacturing world. Yet nobody ever enters the parameter "Pad dimensions". As far as I'm concerned the experiment is a pile of rubbish without this. The Array doesn't tell us what parameters to enter. Anyway, enough ranting....... Don't worry about the semantics regarding the occurence of bridging between the new and old oven. Don't consider DOE or Taguchi. Convection ovens are the standard, going from IR to Convection is a good choice. Pad geometry and stencil apertures will have a much more significant impact. Establish the dimensions used and we can comment. If their geometries aren't suitable then no oven will change the defects due to bridging. Not all is being told here. The profile will have an influence on bridging, but small compared to the effect of pad geometry. Establish what flux is being used in the paste. Let us know the details and we'll sort you out. Regards Edward Brunker PSION COMPUTERS GREENFORD LONDON ______________________________ Reply Separator _________________________________ Subject: [TN] Solder Bridging Author: "TechNet E-Mail Forum." <[log in to unmask]> Energy Technology Systems <[log in to unmask]> at INTERNET Date: 03/02/99 10:58 I have a customer who recently replaced a very old IR reflow oven with a brand new convection one. Since the new oven has been installed they are noticing an increase in solder bridging on some very fine pitch components. Even the customer says that they do not suspect the reflow oven but they cannot place a finger on it. Being the manufacturer of this oven I want to help prove that it is not the problem as none of our other customers have ever complained about solder bridging and from my experiences solder bridging has been reduced dramatically when switching from IR to Convection. Can anyone suggest additional places to look. The area I am most suspect of is the conveyor just prior to reflow. The reflow has an edge conveyor and the linking conveyor just prior to reflow is "power loading" the boards. By power loading I mean the upline conveyor is running considerably faster so that the boards slide a ways onto the conveyor prior to slowing to match the reflow conveyor speed. I have heard that boards can crash into the conveyor pins, other boards, etc. when power loaded and cause components to shift. Could this be the case? I know it can not be related to the energy transfer as the delta on their boards was reduced from 40 degrees C to less than 15 (actually 8 - 15 degrees depending on the board) by switching from IR to convection. Comments? Brian ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################