In order to do this a new profile will be required moving from tin-lead to Pb-free solders. To make sure that your assemblies have good reliable solder joints you want to insure that all the solder joints on the PCB fit the minimum required solder profile provided by your solder paste vendor. Sn63/Pb37) melts at 183C whereas the common tin-silver-copper (SAC) Pb-free alloys melt at 217C.įor Sn63 assemblies it is common to have a peak temperature of approximately 220C, for Pb-free assemblies it is common to have the coolest portion of the board reach a temperature of at least 230C in order to achieve good wetting and solder spread. Marc has authored several industry articles on Soldering, Flux collection, nitrogen use and Lead Free conversion.ĭeveloping a unique profile for tin-lead and lead-free assemblies is critical. Peo has been with Heller Industries for over 20 years and has been President for the past 8 years. So the real trick is to segregate the profiles –not the machines. The Lead Free profile can be 20-40 degrees hotter than the Tin Lead profile so using the Tin Lead profile for Lead Free parts will certainly not provide acceptable results. You have to be sure to run the appropriate profile for the material being processed. The big difference between running Tin Lead and Lead Free is profile. Solder paste stays on the pcb and does not "contaminate" the Reflow oven.Īnd even if Tin Lead or Lead Free solder fell on to the bottom of the oven (as part of a pin-in-paste application for instance) it would not affect any performance at board level. This question is an important one for Wave solder as pot contamination can be a big issue.īut on the Reflow solder side, there really is no issue. iodes ncorporporated A product ine of Diodes Incorporated. February 2019 Diodes Incorporated S 1-408-232-100 T 88-3-4518888 RE)L: All specifications are subMect to change without notice. Al has been a significant contributor to the development and optimization of reflow and rework processes and systems, particularly lead-free transitions and microelectronic applications. Reflow Soldering Profile, Per J-STD-020D, Table 5-2, Pb-Free Devices. His expertise includes through-hole, surface mount and semiconductor packaging with an emphasis on soldering and heat transfer. Consultation with specific oven manufacturers is recommended, they should be able to provide oven related details.Īl Cabral is Regional Sales Manager for Finetech and Martin rework products. If desired, atmosphere samples can be collected and analyzed from strategic locations within the Reflow oven's process chamber to confirm.Īdditionally, oven components or subsystems that inherently collect process by-products such as exhaust manifolds, traps, collectors, condensers and exhaust stacks can be examined as well. Modern convection dominant Reflow ovens exchange atmospheres at relatively high rates, continuously introducing fresh gas (air or N2) and exhausting as required. Intimate contact within the solder interconnects is prohibited by design, limiting lead migration to the Reflow oven's atmosphere. It's highly unlikely that dedicated Reflow ovens are required to process lead base and lead free alloys for traditional SMT applications. How critical is the requirement to use separate reflow ovens for my leaded and lead-free assemblies? Reflow for leaded and lead-free assemblies
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