Ask the Experts
October 11, 2010 - Updated
October 11, 2010 - Originally Posted

Pick and Place Board Deflection

I was on the shop floor and noticed deflection in the 8x8 inch panel that was being populated. Would the deflection in the middle of the panel cause components to sit higher on the paste and thus have a slightly higher solder joint height than components nearer the support rails?

D. H.

Expert Panel Responses

Probably not! Although there are many variables in the behavior of solder joints including: manufacture of solder paste, material make up of the paste, reflow profile etc... If your component is placed squarely in the solder, when the material goes liquid, the solder will wick-up onto the component and bring it down toward the PCB. The bigger concern would be if the board is warped downward to where the component is dropped above the placement point. If the component is not touching both solder pads evenly, you are more likely to experience tomb stoning or bill boarding. Downward warp can easily be corrected by using underside support, in addition some of newer, higher quality equipment is equipped with board surface mapping and component height detection & compensation and automatic underside support features that would eliminated you concerns automatically and significantly reduce your opportunities for error.

Scott Wischoffer
Marketing Manager
Fuji America Corporation
Scott Wischoffer has been in the SMT industry since 1986 with experience in service, training, sales & applications, and marketing.
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