GUIDELINE FOR AUTOMATED REFLOW SOLDERING PROCESS FOR PRODUCTS CONTAINING WIREWOUND TRANSFORMERS Forward The guidelines provided in this application note consider the guidelines of JEDC J-STD-020 and describe the basic surface-mounting assembly requirements for solder reflow of wire wound transformer based products manufactured by Synergy Microwave Corporation. Optimum yields are achieved by careful optimization of the heating profile to allow for package size limitations. Peak Reflow Temperature Determining the maximum allowable peak reflow temperature is a process that involves consideration of the package volume and thickness for Pb-free soldering processes as described in Table I below: Table I. Package peak reflow temperature (Tp) Reflow Process Thickness Pb-Free >2.5 mm Volume <350 mm 3 230oC +0/-5oC >350 mm3 >2000 mm3 225oC +0/-5oC 225oC +0/-5oC tP Tp Critical Zone TL to TP Temperature Ramp-up TL tL Tsmax Ramp-down Tsmin tS Preheat 25oC t 25oC to Peak Time Figure 1. 1 of 3 Temperature reflow profile AN7301 Rev. B 11/02/09 Table II. Reflow profile parameters Reflow Profile Feature Average ramp-up rate (Tsmax to Tp) Preheat -Minimum Temperature (TSmin) -Maximum Temperature (TSmax) -Time (TSmin to TSmax) Time maintained above: -Minimum Temperature (TL) -Time (tL) Peak Temperature (Tp) Time within 5oC of actual peak temperature (tp) Ramp-down rate Time at 25oC to Peak Temperature Pb-Free Assembly 3oC/second max. 150oC 200oC 60 – 180 seconds 217oC 60 – 150 seconds Per Table I 10 - 20 seconds max. 6oC/second max. 8 minutes max. Consideration for maximum reflow temperature limits – One reflow pass For technical assistance contact: Synergy Microwave Corporation 201 McLean Boulevard Paterson, NJ 07504 Tel. 973-881-8800 Fax 973-881-8361 Email: [email protected] 2 of 3 AN7301 Rev. B 11/02/09 - Recommended Solder Reflow profile for Pb-Free Process - Temperature Tp Tp=230oC Ramp-up to tp 60 sec 180oC 220oC 30 sec (+/-10 sec Reflow) 150oC 1 to 5oC per sec Ramp down 90 (+/-30 sec) Preheat 25oC Heating Time (Sec) 3 of 3 AN7301 Rev. B 11/02/09