BTU-回流焊冷却斜率控制.pdf

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BTU-回流焊冷却斜率控制.pdf

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BTU-回流焊冷却斜率控制

Controlling Reflow Oven Cooling Rates Nepcon Shanghai April 25, 2007 Rob DiMatteo Product Manager BTU International Cooling Control Why it s important ? • Integral part of the reflow process • Solder joint is not formed until solder is cooled below liquidus temperature • Long term reliability influenced by cooling rate • Product handling – exit temperatures Lead Free Solders It s all about control: Temperature uniformity Process repeatability Heating and cooling rates Atmosphere control Material consistency Reflow Profile Cooling Stages Peak to liquidus Liquidus to exit Exit to ambient Cooling occurs from Peak Temperature down to ambient! Heating the Product All about BTU s Moving thermal Heaters energy from the heater to the product Product Belt Cooling the Product All about BTU s Removing thermal energy from the product. Product Belt Cooling Rates • Typical SMT Cooling Rate – 2 - 4C / second • Slow Cooling – 0.5 – 1.9 C / second • Fast Cooling – 4 – 6 C / second Typical Cooling Profile Peak to Liquidus - 2.0C / second