MEASUREMENT VARIATION IN THE FILL OF INTRUSIVELY REFLOWED LEAD FREE SOLDER JOINTS WITH DIFFERENT BOARD FINISHES BY X-RAY INSPECTION

摘要

As the implications of switching to using lead-freernmaterials for printed wiring board (PWB) assembly havernparticular impact on the equipment and capability for wavernsoldering, it is attractive to consider the applicability ofrnusing the pin-in-hole intrusive reflow technique as anrnalternative within the production environment. Eliminatingrnwave soldering can reduce the cost of implementing leadfreernand some of the common process defects.rnThis paper will report on the results from percentage-fillrnmeasurements of intrusively reflowed lead-free solderrnjoints, where the same lead-free alloy has been applied tornboards with different finishes. The design rules, hole sizernand other factors associated with intrusive reflow defectrnelimination will be outlined and compared with thernintrusive reflow requirements in the latest IPC 610-Drnstandard. The measurements have been taken by x-rayrninspection at oblique angle views. Variation in the fillrnpercentage of the solder joints after reflow will berndiscussed in terms of the nature of the board finishes usedrnand the conditions that are applied when optimising therncomplete pin-in-hole intrusive reflow process.