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Help! I'm killing my DotStars!
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Help! I'm killing my DotStars!

by Disciple on Fri Jan 11, 2019 1:55 am

I bought the 10-pack of 5050's and the breakout boards to take my first crack at dealing with SMD components. With a pointy iron, I got the first one to work by tinning everything and hot-joining them. Yay! But I melted the 5050 package on the second and third. Today I tried dots of solder paste, a new hot air station, and Made in NYC videos to imitate. Everything seemed to take, and my fourth DotStar lit up green, blue, but not red. Woe. The clock and data lines of pixels one and four chain up nicely in either order, but pixel four is still missing a color.
Either that pixel was already defective, or I damaged it. The pixels have been out of their humidity-seal for months. Did heat and moisture break my 5050? Can I dry out my last six lest they break as well, like 15 minutes under a blow-dryer and into a zipper bag? I'm hoping to salvage my melted ones, too. If I can get eight pixels working, my POV idea can proceed. What should my next step be with this moisture problem? Thanks for reading.

Hallelujah!
Disciple

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Re: Help! I'm killing my DotStars!

by Keebie81 on Fri Jan 11, 2019 9:30 pm

Maybe instead of a hot air station try the electric skillet reflow method. Ive used that for when repairing some bad neopixel rings

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Re: Help! I'm killing my DotStars!

by franklin97355 on Fri Jan 11, 2019 11:28 pm

Dotstars and Neopixels are VERY sensitive to temperature fluctuations and tend to crack internally. Even with environmentally controlled conditions and proper soldering profiles it can be hit and miss.

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Re: Help! I'm killing my DotStars!

by jps2000 on Sat Jan 12, 2019 12:11 am

There is also a 138°C solder paste available. I like it for critical hot air soldering because you gain time to adjust components ( < =0.5mm pitch)

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Re: Help! I'm killing my DotStars!

by Disciple on Sat Jan 19, 2019 4:38 am

Well, thanks for the tips. I'll be looking into them. Websearch time.

My dad just obtained a USB microscope, and I'm surprised at what I see. That my pixels work at all in their condition is amazing. The good one is scorched at the edges, but the window is smooth and clear. The injured pixel has a deformed window, and maybe a crack next to the blue emitter.
HotStars001.jpg
HotStars001.jpg (129.91 KiB) Viewed 21 times
Can a skillet do the job with less damage than this? Research will tell, I guess.

Hallelujah!
Disciple

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Please be positive and constructive with your questions and comments.