reflow soldering process

[gauravkothari23]

Hi all...
i need a small guidance about re-flow soldering..
i have made a small PCB and about to assemble it using some SMD components.
i just want to ask that the temperature to maintain under re-flow soldering is around 250 degree Celsius... so in such a temperature wont the SMD components get damaged. because i think around 80 to 100 degree Celsius the components get burned out.
can anybody please guide me for this...

 

[DigitalDeath]

The actual reflow temperature is much higher than 100 degrees C.
SMD components should have no problem.

Here's an example of a reflow temperature profile:

 

[KlausST]

Hi,

so in such a temperature wont the SMD components get damaged. because i think around 80 to 100 degree Celsius the components get burned out.
can anybody please guide me for this...

If they would get damaged, no SMD board would work.

The ICs don´t work at those temperatures, so please don´t power your PCB during soldering ;-)

For homebrew soldering I recommend to pre-warm it to about 100°C for half a minute before going above 200°C.
(Usually you can´t do a continous temperature rise rate of about 2°C/s, but the flux needs some time to become activated and the thinner needs to be dried before the reflow phase)

So maybe you have two plates, one with 110..120°C and the other with about 220°C. (don´t cool down the PCB between pre-heat and soldering)

Klaus

 

[gauravkothari23]

Thanks a lot you all....
i have tested re-flow soldering by soldering a SMD LED and resistor and it works perfectly...
what for cooling process....
should i use a blower to cool it down at room temperature or can i put the PCB to freezer for immediate cooling.

 

[KlausST]

Hi,

Do slow cooling at free air.
Fast cooling generates mechanical stress.

I usually place it for some seconds back to the 100° plate, then free air.

Klaus