I am sending this question again, soon after I sent the question, I lost contact with the forum and have just now signed back on. Still looking for an answer: Question: Our company processes circuit boards in panel form, (eg. six three inch square boards forming a panel that will be six inches wide by nine inches long.) The individual circuit boards are joined to each other with small webs, 0.25"long by 0.060" wide, separated by two to three inch spaces. A shear is used to separate the individual boards from the panel after the wave solder operation. Most of our products have been Type III assemblies, CEM1 board material, but we have also been doing Type II assemblies, FR4 board material for the past year. Our problem is that the larger, multi board FR4 panels(0.060" thick) are bowing during the reflow process across the width of the panel by as much as 1/4". The bow creates problems in the next operations of thru-hole insertion or SMT placement. The bowing appears to be compounded by the panels while they are in a magazine. I feel that this is due primarily to the practice of using the webs to connect the circuit boards within the panel. However, if the amount of web material is increased, we will have to switch from shearing to a routing process, scored panels or punch/return style boards(I hear that these warp also!). Another option is a pallet, but this will affect the flow-thru process, non-value added labor, and increases tooling cost (we are a high volume shop). Is there another method to eliminate the warp problem, or will FR4 material always warp in the reflow process, if so by how much? Is there a panel width, with or without webs that the material will not warp? I am presently planning to purchase a new reflow oven, and a center board support is another option. I am using a standard reflow profile with standard soak zone temperatures, liquidous temperatures, and peak temperatures. *************************************************************************** * 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. * ***************************************************************************