LED solder overheat?

I hand soldered some surface mount LEDs and most of them seem broken now. I assume I overheated them. However, I`ve soldered lots of other kinds of surface mount LEDs with no problems, even really small ones were fine. The problem was with some warm white (yellowy white) LEDs. I removed some of them to check for a soldering error and they still won`t light up when I test them so I guess they are really broken. This is a bummer because I paid over 100 yen a piece for them.

Do you think I overheated these LEDs when I soldered them? 

How can I avoid this problem in the future?

Why did this only happen with this particular kind of surface mount LED? 

framistan6 years ago
They MIGHT have been bad before you installed them. You can check LED's using a digital volt meter by setting your meter to "diode test" If you forward bias the LED, it should light up (dimmly). if it doesn't light up, it is bad.
Its really easy to damage SMD LEDs with too much heat. Did you use a conventional iron ? A hot-air gun is a much better way to set them.
rickharris6 years ago
Are they the right way round? Did you include a series resistor.