Hello,

Has anyone ever seen any studies or papers about the effects of running FR-4, .062"Thk, boards across the wave solder twice. These are 2-sided, SMT (no BGA's), .062" Thk. and about 7.5"W X 8.0"L. The first pass resulted in boards sagging in the middle (approx .080" bow along the 7.5" width), and then being held in a warped state when the thru hole joints solidified. When these boards are placed in a custom fixture and ran across the wave again they relax and are straight. I'd like to know if anyone has had any experiences like this and did the results have any effect on the life of the boards? Did it effect the board function. Are there any papers written or data available in someone's archives that would support no harm has been done to the SMT solder joints being flexed (twice). Or no degradation of the 0603 ceramic caps being flexed. No harm, no foul so to speak? I haven't been able to find any white papers to support it or critique the process so I'd appreciate any feed back. Thanks. 

Jack Bryant

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