Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

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Material Property Change During reflow

#6290

Material Property Change During reflow | 23 August, 2000

Dr. Lee: How do the metallurgical properties of solder change during a second reflow. Please provide detail on this phenomenon.

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Dr. Ning-Cheng Lee

#6291

Re: Material Property Change During reflow | 23 August, 2000

During the second reflow, the solder remelts and resolidifies. In general, the reflow temperature is not high enough to erase the microstructure developed during the first reflow. As a result, the net effect of a second reflow typically is grain coarsening due to annealing experienced at cooling stage. In addition, more intermetallics will be formed, as a straight forward result of more heat input.

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