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Comment by csdvrx | Hacker News Reader

For smaller numbers of connections, you don't even need a stencil if you how to use surface tension and have a fine tipped soldering iron.

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Yup, the trick though is you want some way to get all the pads balled to roughly the same height - otherwise when you heat it to solder it and the chip floats on the pads one or two may be too high to make contact ... or there's too much solder and it squeezes out and causes a hidden short.

The process of filling each hole in the stencil with the same amount of solder and carefully scraping any excess off of the top effectively adds the same amount to each ball

> Yup, the trick though is you want some way to get all the pads balled to roughly the same height -

I see you are familiar with the method :)

Here's another "ghetto BGA reball" trick if that happens: lower the temperature of your iron to make the "pseudo balls" that are too big thinner by drawing some paste away into a vertical line extending up : let it cool down and just trim it to length with nail clippers.

You can get balls again by rewarming a bit - ideally with a special IR heater to avoid pushing the balls away by the flow of air coming from a hot hairgun, but in a pinch a regular oven can do the job (prebake to temp of course)

If you see this late reply - what sorts of IR heaters would I be looking for?

that reminds me of when I tried to soldier an extra chip on my PS1 and instead pulled up an original one oops

Letting people know you could pull this off eventually leads to the inevitable assignment in which you need to solder a dozen of NAND chips in some obscure package that nobody seems to have a stencil for :) Oh and the deadline is 24 hours away.

Exactly why I'm only saying that anonymously here on HN :)

FYI, I also do some SMD by hand. It's not very hard with leaded paste. It's a very practical skill to have when you only use it for yourself and a few select friends (read: not colleagues!)

Good thing we can reach you through GitHub ;-)

Half joking, if you have forgotten that you added that link here's your chance to remove it B-)

And... it's gone now! (Thanks for reminding me BTW)

I prefer keeping a low profile. Because I like speaking my mind freely, which I might not do if my account was linked to my name.

You can never be too careful, you can get cancelled for thoughts that go against groupthink.

If you dealing with these kinds of jobs you either get a generic stencil and use a kapton tape as a mask or you invest in a laser cutter capable of cutting stencils in a half/quarter of a mil stainless sheet.

Also RoHS goes out of the window and you use a leaded tin which makes your life so much easier, as well as usually guarantees a longer life time for the fix because it’s far more ductile after soldering.

Unleaded solder is awful, sadly.

If you see this late reply - what if you use a fume extractor turned up to "headphones with music required"-dB, connected to an optimal exhaust configuration?

Sounds profitable, whats the problem?

https://www.youtube.com/watch?v=I4m0LoGx7Qo

you can also go one ball at a time https://www.youtube.com/watch?v=LrXL1uGs0vU

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