>Dear MEMS colleagues, > Has anyone attempted to solder onto sputtered metal, what >procedure and >metal will optimize the bond (currently I'm working with AlCu bond pads)? >Wirebonding leads are too thin and weak. > Thanks, > George Lopez > CMU MEMS I realize that I am responding to this late, but I only just discovered the archive, so this is about all I can do. This email response was also initiated as a new thread, but I hope the title match will work well enough. Onward! If you are seriously considering solder I will assume that you are developing a test structure, since your average solder ball is a bit too big for a microsystem. In that case, you may be able to do something similar to what I did. If your active electrodes are small, but you can form good wirebonds to them, you have the option of designing a contact pad that is electrically isolated from the active electrode. So for my 7mm*7mm silicon die, I developed a series of electrically isolated bond pads that were far enough apart that I could make a wirebond contact to them and then safely contact them with a conductive epoxy. (I used Epotek 410 in my later experiments.) If you go to the following webpage, you can see a diagram of my silcon die, in its earliest form, and its most advanced form. http://www.demodave.com/presentation/sld027.htm By way of exmplanation, the figure on the right is the plan view of the die that should interest you. On the bottom, there are 4 squares, representing 0.3 mm squares, which are the contact pads. The array of square electrodes in the top half of the diagram are my top electrodes, varying in size from 0.1 to 1.5 mm squares. At the far right and top, there is a contact to the bottom electrode, which I would wirebond to the rightmost of the four contact pads on the bottom of the die. Feel free to borrow the .gif, because you can see it better when you isolate it from the webpage. If you do anything real with it, please cite my thesis in the literature. My electrodes are 5000A layers of gold, because I am using a gold wire for the wirebonding. The silver-based Epotek 410 doesn't seem to have any problems making good electrical contacts to that material. I realize that this isn't an ideal connection for a single plane MEMS, but it worked in my test structures. David -- David Drinkwater 3530 Bloomington Ave. S. #3 Minneapolis, MN 55407 Phone: 612.724.6359 drink003@tc.umn.edu http://www.demodave.com