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Mixing Non-Rohs and Rohs Compliant Temperatures

newbie

Feb 15, 2010
2
Joined
Feb 15, 2010
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2
Hi,

Not sure if this is the place for this, but I need some advice please on the effects of running a non-RoHS/Leaded solder paste through a reflow oven at RoHS/Non-Leaded temperatures.

Peak temperature of the Non-RoHS profile is 270 degrees whilst the peak temperature of the RoHS profile is 313 degrees. (These are the oven settings, not necessarily the actual temperatures achieved in the oven... the point being that the RoHS profile is around 45 degrees higher).

In addition, what would be the effect on a 1206 non-RoHS resistor of the higher temperatures... I can't find any information in the parts datasheet...

Thanks
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
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25,510
I doubt there would be any issue for the solder paste itself. The flux will do its thing, and the paste will melt. The higher temp won't affect the solder.

However, it may cause lead contamination of your oven (I'm not sure how strict ROHS qualification is and whether this would cause sufficient lead contamination of a subsequent board to cause problems.

I would suggest that the non-ROHS component would simply not be rated for that temperature profile. I would not expect it to cause huge problems, but if the manufacturer hasn't tested it, then all bets are off.

If this is for hobby work, I would test it a few times to see what happens.

However if it's for something that requires compliance with international standards, you'd be best to avoid it (unless you can find manufacturer recommendations).
 

newbie

Feb 15, 2010
2
Joined
Feb 15, 2010
Messages
2
Thanks Steve. We've noticed that some legs on a couple of PLCCs have not soldered properly and that there are a lot of solder balls congregating underneath resistors, caps and diodes...

I'm taking that as a bad sign as to how the solder paste was affected in the oven. I'm going to recommend scrapping the build and starting again.

Thanks for your comments
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
Something other than beautifully (re)flowed solder joints definitely seems like a bad sign.
 
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