Hi there, Amith! "I have seen lot of Dross formation every time I power ON the Wave soldering machine. Though I use dross reducing powder, still lot of dross gets formed. What are all the Major factors affecting this? " This one is from experience. I can suggest three things you can check to reduce excessive dross formation on your wave soldering machine. 1. Temperature. High heat facilitates formation of oxide which is the dross you are seeing (tin oxide/lead oxide). Try a solder temperature lower than 270 deg C. 2. Pump Speed. Faster solder flow rate will increase the contact between your solder and surrounding air (which contains oxygen, which forms oxide....) 3. Solder Contaminants. If 1 and 2 fail, have your solder analysed. Consult the ff specifications (BS219, ASTM B32-66T). See if your virgin solder bars comply to the specs, too. We had this problem (increased solder dross formation) before and item #2 worked for us. > "If it is Solder impurities , what are those ?" This is from my notes: " As little as 0.0005% (by weight) Al may increase dross rate without affecting joint formation.0.001 may result in a sluggish or gritty solder." I don't know what other metal impurities can cause increased dross formation. Perhaps other Technetters can help us with this. Hope I had been of help. Best Regards, > Lei Tumibay > Lead Finish Group - Assembly Engineering > Analog Devices - General Trias > Cavite, Philippines > E-mail: [log in to unmask] > http://www.analog.com > ################################################################ 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 ################################################################