Our major problems were in the areas of controlling part placement and lead misalignment to prevent opens during assembly. This was mostly equipment and training related and essentially had to do with getting people used to the fragility of these leads when placing the devices (we autoplaced but VERY SMALL forces can move leads out of alignment (vertically or horizontally). As we conquered this, we also had some problems on "mixed technology" PWAs with fine pitch on top and also wave soldered (PTH) devices. Problem was that the wave solder schedule was "too hot" and tended to cause localized reflow/voiding under the fine pitch device leads. These joints would look OK but have very little mechanical strength. We had to lower wave solder preheats/dwells to overcome this. IBM has had similar issues (I believe this was reported in a recent IPC Tech Review article. Jim Maguire Boeing Defense & Space Group [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: transition to fine pitch Author: [log in to unmask] at esdigate Date: 7/5/95 8:56 AM Hello, Our design requirements are driving us to finer pitch technologies. We currently assemble 50mil pitch devices. My expectation is that our next generation of products will be 20 to 25 mil pitch. I am interested in hearing war stories of people who have been through this process. Specifically, what was the number one problem encountered and how was it overcome? Thanks Mitch Austin Itron [log in to unmask]