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Soldering WS2812B - Damaged chips?
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Soldering WS2812B - Damaged chips?

by garetbiglow on Thu Dec 24, 2015 6:52 pm

So recently, myself and another fellow from work ordered some of these WS2812's (neopixels) from Adafruit. We ordered them loose, so we could build our own boards here in our shop and run them through our reflow oven. We use pneumatically dispensed solder paste and a conveyer style reflow oven. The reflow curve is calibrated frequently and does not exceed 250 degrees Celsius. Upon testing the WS2812's, approximately 30 percent of the LED's had failures (missing R or G or B LED diode).

I'm wondering what the proper protocol for soldering these chips is? I found this on adafruit's product page for the WS2812B:

"These raw LEDs are cut from a reel and/or might be loose. They may not suitable for pick & place + reflow. WS2812's are notoriously difficult to use in an automated process due to being very sensitive to moisure and temperature. We recommend these for careful hand soldering only! Comes in a package with 10 individual LEDs."

Hand soldering? That's crazy. These chips are not being hand soldered when being made into panels in China. Our project required solder ~300 of them. There must be a better way?

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Re: Soldering WS2812B - Damaged chips?

by franklin97355 on Thu Dec 24, 2015 7:57 pm

In most cases the chips are slow baked to drive out the moisture then tempered before reflow. I would check with a supplier in China for chips and their recommended soldering process.

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Re: Soldering WS2812B - Damaged chips?

by garetbiglow on Wed Apr 27, 2016 7:16 pm

What do you mean by "tempered"? What does that process look like?

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Re: Soldering WS2812B - Damaged chips?

by franklin97355 on Wed Apr 27, 2016 7:24 pm

In this case it means slowly heating the chips to avoid thermal shock when soldering.

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Please be positive and constructive with your questions and comments.