Ask the Experts
April 8, 2014 - Updated
April 2, 2014 - Originally Posted

Minimum Component Lead to Lead Spacing for Wave Soldering

What is the recommended minimum lead to lead spacing for through hole components run through a wave soldering system? Would the spacing be different for lead-fee solder compared to leaded solder?


Expert Panel Responses

Theminimum practical pitch for multi-lead components such as connectors is about1.27mm (0.050); I have not personally dealt with any with smaller pitches. Itis in theory possible to do smaller pitches, but the required hole diameter,and thus the maximum lead size, becomes very small. Pad sizes are also severelylimited, which will affect soldering performance. The small hole alsorepresents a problem for getting flux penetration and hole fill. The minimum pitch should not be different for Pb-free vs. SnPb. Ineither case, it is necessary to tightly control lead protrusion to reduceshorting risk. It is potentially more critical with Pb-free due to the highersolder surface tension.

Fritz Byle
Process Engineer
Fritz's career in electronics manufacturing has included diverse engineering roles including PWB fabrication, thick film print & fire, SMT and wave/selective solder process engineering, and electronics materials development and marketing. Fritz's educational background is in mechanical engineering with an emphasis on materials science. Design of Experiments (DoE) techniques have been an area of independent study. Fritz has published over a dozen papers at various industry conferences.
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