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The Popcorn Wing

A project log for Keys FeatherWing

A FeatherWing with three keyboard keys.

de∫hipude∫hipu 11/19/2019 at 09:306 Comments

Yeah, I decided to give the tiny keyboard thingy one more try, this time with solder paste and hot air gun. Turns out those small buttons have a pretty narrow thermal curve — they get crispy really easily.

Also, weren't they supposed to just magically pop right into their places, instead of clustering together into a single mega-button?

Discussions

Christian Walther wrote 11/20/2019 at 23:54 point

Same thing happened to me when I tried desoldering such a button from the D1 mini PewPew shield using hot air. Soldering them in the oven at ~220 °C peak on the PicoPew worked well though.

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de∫hipu wrote 11/21/2019 at 10:05 point

Wait, you can solder things at 220°C? I thought solder melts at ~250°C or more if it's lead free...

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Christian Walther wrote 11/21/2019 at 10:16 point

The Sn63/Pb37 solder paste I used is labeled “183°C” (https://www.banggood.com/XG-Z40-10cc-Syringe-Solder-Paste-Flux-Paste-Sn63Pb37-25-45um-p-973158.html) and the oven controller heats to 218° and then overshoots a little (https://www.rocketscream.com/blog/docs-item/tiny-reflow-controller/).

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de∫hipu wrote 11/21/2019 at 10:26 point

you are right, I wonder why my soldering iron is set to 400°C...

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Jan wrote 11/19/2019 at 13:46 point

"Also, weren't they supposed to just magically pop right into their places, instead of clustering together into a single mega-button?" This really depends on the amount and type of solder paste (and pad size) AND hot air flow rate.

I suggest putting a piece of steel or alu on your stove and use that, really reliable!

Edit: I just saw that @davedarko had the exact same idea just before me :)

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davedarko wrote 11/19/2019 at 13:41 point

this might work better on some sort of hotplate? Maybe JLCPCB has more luck with a pcba run?

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