| Hello, | | I need some users information about "hot air knife" after the wave | bath: | - Defects reduction ? | - In what kind of boards(TH/SMT SOICS ect.) it is applied ? | - Where can I purchase it as a retrofit (Soltec Delta 6622cc) ? | | Thanks | Roni Haviv - Tech. Eng. | ECI Telecom - ISRAEL Roni, Hot air (or nitrogen) knives are one of the greatest inventions known to assemblers. They open up your process window, reduce your defects, and open up your design window as well. You can use them on just about any type of technology. For through-hole only boards, you run a shallow angle to the board to blow through the leads. For SMT and mixed tech, you run the air stream more perpendicular to the boards to avoid blowing solder to the back of the pad, or blowing parts off the board completely. You can run your wave higher without worrying about bridges from a bad peel off (this is a huge help if you don't have attentive operators) You can let your designers jam more components on less real estate and use finer pitch connectors because you'll be able to debridge. You can run SOIC's at nearly perfect yields without thieve pads. But all this doesn't come for free. You have to be cautious about your knife settings. You can blow solder out of holes, onto the top of boards, up dip leads to create bridges on the top side, all over the machine, or, I've even seen people blow lead out the load end of the machine onto their operators because they had very poor knife settings. You can also blow tant caps and SOICS's right off the board. Or you can hit the board with such a huge third temperature spike thatyou reflow topside components. It's not that difficult to control, though. I've found that low air pressures and moderately high (650F) temperatures work the best on my mixed technology boards. And I would highly recommend the knife. I don't know who retrofits them to Soltec machines, however. I've seen retrofits to Sesnby machines that were installed by nitrogen providers, and I was far less than impressed. Have you contacted Soltec directly? They were talking about a knife-like apparatus at Nepcon last year. I think Electrovert has the patent on the knife itself for wave soldering. Good Luck, Chrys
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Hello,
I need some users information about "hot ai...
- May 28, 1998
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