LED SMD CHIP FAILURE - HAS ME SCRATCHING MY HEAD.

Hello, I'm new here, but I thought maybe someone can help me.

I've been producing LED lights in my workshop since last summer. I use a 10w SMD Chip in side a metal housing, with a driver and heatsink. I've noticed over the past month or so i have been experiencing a lot failures, before I had none, or they were very rare.

Sometimes the LED fails right after I solder the two wires to it. By fail I mean usually one or two lines in the LED cease to light up.

This last time the LED didn't fail until I poured the epoxy over the LED [I use clear epoxy to produce a lens].

I am wondering if temperature could be a problem? My work shop is not heated during the nights. I turn the heat on when I go in to work.

Do you think where the LED chips are cold, and they come in contact with the solder that it is damaging them?

Also, I heat the EPOXY to about 100F degrees before pouring it. Could that damage the LED?

I did not have this problem at all during warm weather.

I use a 10watt driver to test my lights, and when the failure occurs it occurs instantly. I'm not overheating the light by using it with out an heat sink, or over powering the light.

What do you think?

The heat can damage them but typically only around 160F does it become an issue. I think I may have had an Xml 16mm led die to heat last night it was working fine then suddenly it stopped working batteries are fine switch is fine and it was direct drive by the design of the dropin. The thing is visually the led looks fine. It just does not work.

If the LED and substrate are cold, you could likely be giving the LED a thermal shock with the hot soldering iron. I used to have that problem on occasion with the old XR-E LEDs, until I started to preheat the LED before soldering. Try preheating the LED and heatsink using a mug warmer, or other type device. For the epoxy, try applying it indoors at room temperature. You will likely get a clearer result than in the cold workshop environment.

I would be interested in seeing what you are building. It sounds interesting.

datiLED said:

If the LED and substrate are cold, you could likely be giving the LED a thermal shock with the hot soldering iron. I used to have that problem on occasion with the old XR-E LEDs, until I started to preheat the LED before soldering. Try preheating the LED and heatsink using a mug warmer, or other type device. For the epoxy, try applying it indoors at room temperature. You will likely get a clearer result than in the cold workshop environment.

I would be interested in seeing what you are building. It sounds interesting.

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Sounds like good advice. I think it's probably thermal shock too.

I'd also be interested in what you're building.

Hello,

You guys are correct, it was thermal shock. The Work shop was dropping to 25 F at night. When I solder them COLD they have a high failure rate. So I pre-heated them, and they did better, but I also learned that if I drop the freshly soldered LED into the Brass housing [which was COLD], it would kill it too!

So I have to pre-heat the LED'S and the Brass Housing,, or let the LED's cool completely before assembly..

Thanks for the advice.

God Bless
Martin

www.babylonforsaken.com