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Peak Temperature during reflow

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aj

#54883

Peak Temperature during Leadfree reflow | 28 May, 2008

Hi all,

I would like to know what sort of peak temps people are seeing during reflow - I understand that there are many variables that contribute to this but there should be an average through out all the profiles.

We are still seeing issues with delamination on & off but I am confident that our process is good.

On average our PCB peak Temp is 248-250 0c.

All replies greatly appreciated.

aj...

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#54884

Peak Temperature during Leadfree reflow | 28 May, 2008

Hi, AJ,

In general, the peak PCB temperature is variable depending on the profile used. We try to keep our peak temperatures in line with the paste manufacturers recommended temperatures; ignoring the peak temps for the PCBs. For the peak temps you mentioned, I assume this is a lead free process.

We profile all assemblies prior to production. Since we run lead free and leaded assemblies, we achieve different peak temperatures. For our leaded assemblies, we try to hold the peak below 215 degrees. For lead-free assemblies, we try to hold the peak below 249.

Cheers ..rob

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#54885

Peak Temperature during Leadfree reflow | 28 May, 2008

I've talked to several Applications Engineers and Chemists from a couple of different paste manufacturers and they confirm that the profiles on their data sheets are nothing but guidelines. It's up to you, Process Engineer or Process Tech, to develop a thermal profile that works for the assemblies that you run in your shop.

The 248�C to 250�C that you mention is typical for lead-free, but again, just a guideline. For a leaded process, if you're reflowing SAC/RoHS BGAs, then obviously you'll want to be above 217�C and peak about 10�C higher. (Hybrid Profile).

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