Assuming you mean surface mount LEDs, this anecdote might be relevant.
I bought 100 LEDs from DigiKey, specifically (THESE). My selection criteria were cost, cost, cost, size=1206, cost, cost, cost, brightness, and cost. Because they were so inexpensive, I assume these are representative of most SMD LEDs.
They arrived from DigiKey in a sealed Moisture Barrier Bag which contained a Humidity Indicator Card. Affixed to the bag was a label which said:
Since I hand-soldered them to my PCB, without using a reflow oven, I cheerfully ignored the label.
I bought 100 LEDs from DigiKey, specifically (THESE). My selection criteria were cost, cost, cost, size=1206, cost, cost, cost, brightness, and cost. Because they were so inexpensive, I assume these are representative of most SMD LEDs.
They arrived from DigiKey in a sealed Moisture Barrier Bag which contained a Humidity Indicator Card. Affixed to the bag was a label which said:
- Calculated shelf life in sealed bag: 12 months at < 40 Celsius and < 90% relative humidity (RH)
- After bag is opened, devices that will be subjected to reflow solder or other high temperature processes must be EITHER (a) mounted within 168 hours of factory conditions 30 Celsius / 10% RH; (b) stored at <10% RH
- Devices require bake, before mounting if: (a) Humidity Indicator Card is >20% when read at 23C; (b) 2a or 2b not met
- If baking is required, devices may be baked for 48 hours at 125 +/- 5 Celsius
Since I hand-soldered them to my PCB, without using a reflow oven, I cheerfully ignored the label.
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As Mark has already explained, check for moisture sensitivity, LEDs can blow up during reflow, due to moisture being trapped in the device outgassing with some force during reflow and rendering the LED useless.
Standard LEDs are usually wave or selectively soldered so the plastic housing does not get that hot, so you also need to check that the LED body is suitable for Intrusive reflow (Pin in Paste).
Standard LEDs are usually wave or selectively soldered so the plastic housing does not get that hot, so you also need to check that the LED body is suitable for Intrusive reflow (Pin in Paste).
Thank you, that is all I need to know. I knew about wave and selective soldering, my question was for reflow and you answered that.
Thanks again
If you take parts intended for reflow out of their moisture controlled packaging for more than 24-48 hours, you generally have to bake them for a while before letting them go through reflow. I seem to recall the temperature of the drying bake being around 100~125 C. Once all the moisture is out of the part, you can send it through reflow.
Edit: Just realized this is the same answer as Post #2. DOH!
~Tom
Edit: Just realized this is the same answer as Post #2. DOH!
~Tom
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A standard T1-3/4(5mm) Led. No,
unless the package data specifically states that it can.
If there is no re-flow data, then the assumption is not.
For a Cree C513A (5mm)
Max. 260°C for 3 sec. max.
(3 mm from the base of the epoxy bulb)
For a Cree smt type
In testing, Cree has found XLamp XP- E LEDs to be compatible with JEDEC J-STD-020C,
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