Yes, you are correct. sorry about missing that very important point. ---------- From: TechNet-request To: TechNet-request; TechNet Subject: Re[2]: ASSY: Post-wave Warpage Date: Friday, May 17, 1996 14:42 Whoa. Before you bake your boards higher than their Tg, you must figure out if your components can stand that kind of temperature. You may end up with a board full of melted connectors (generally 85C ~ 105C rated). Tg may be in the 130C range. We have baked BARE boards to relieve warpage, but never a loaded board. Regards, Roger Held Hitachi Computer Products (America) ______________________________ Reply Separator _________________________________ Subject: RE: ASSY: Post-wave Warpage Author: [log in to unmask] at Internet-HICAM-OK Date: 5/17/96 1:43 PM bake the board flat in an oven. You must get the board above its glass transition temperature. Bake for a least 3 hrs. and allow a slow cool down with the weight still applied. Some warpadge occurs from the board design, random placement of holes in the board, bad distribution of copper layers or component weight. If this is the case a fixture that holds the boards shape may need to be developed for wave process. Other warpedge could be a warning sign that somthing in your process has gone wrong. To high a temperature, bad fixturing during wave etc.... Good luck ---------- From: TechNet-request To: TechNet Subject: ASSY: Post-wave Warpage Date: Friday, May 17, 1996 12:28 Can anyone give me some suggestions on returning a board to flat after it has gone over the wave? I have a new customer who has been using someone else to solder his boards and is experiencing warpage after it has been wave soldered. The board measures 16 cm x 23.5 cm with two (2) 96-pin connectors (.100" spacing) along the 23.5 cm side of the board. He said the other shop's solder pot is about 480 degrees and it is assumed they are running the board with the short side in the grippers so as to avoid hand-soldering the 96-pin connectors since they hang off the egde of the board. Some additional data: I.C. orientation: 33 run east-west, 11 run north-south, 1 PLL. There is one 20-mil pitch SMT QFP device on the board. The QFP is the only SMT device on the board. Any ideas on how to avoid the warpage in the first place and when you do have it, how to eliminate it? Thanks to all who may contribute.