# What does "Bake a LED" means ????



## cdrov (May 29, 2008)

In the CREE tech specs of XR-E i read the following..


Baking Conditions
It is not necessary to bake all XLamp LEDs. Only the LEDs that meet all of the following criteria must be baked:
LEDs that have been removed from the original MBB packaging 
LEDs that have been exposed to a humid environment longer than listed in the Moisture Sensitivity section above
LEDs that have not been soldered 
LEDs should be baked at 80ºC for 24 hours. LEDs may be baked on the original reels. Remove LEDs from MBB packaging before baking. Do not bake parts at temperatures higher than 80ºC. This baking operation resets the exposure time as defined in the Moisture Sensitivity section above

What does that means ?? Do i have to put them in the oven??? Or should i ignore it?


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## Skywise (May 29, 2008)

Baking is the heating of electronic component to remove moisture, usually from improper or long storage.


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## VidPro (May 29, 2008)

i think (meaning not know) that its nessisary when it will be running through a Machine to solder in a "bath" when it smacks the hot solder baths any moisture would steam harshly and ruin things.
so unless your soldering in a pool of solder, or baking to solder, or other methods that heat up the whole thing quickly, hand soldering correctally shouldnt be a problem.
also i would assume anyone who is doing 100+ items, is getting them out of the sealed package, or taking proper precautions.


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## adamlau (May 29, 2008)

Baking on an application of MILITEC-1 on a LunaSol 27  ...


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## Probedude (May 30, 2008)

Skywise said:


> Baking is the heating of electronic component to remove moisture, usually from improper or long storage.



Yep,
The plastic package of IC's absorb moisture over time. During the reflow process the moisture expands and can cause damage to the package of the device - delamination or even bond wire breakage (the breakage is what we experienced on our product).

So there's a max exposure time that IC's are allowed to sit before being reflowed. If it is exceeded, the chips need to be 'baked' out to remove the moisture gradually. With our chips it's 168 hours. For RoHS chips its even shorter due to the higher reflow temperatures.

Plastic packages absorbing moisture and damaging chips? I thought the vendor was pulling my leg when they said that's what our problems were. 
Dave


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