Electronics > FPGA

FPGA/CPLDs that are hand solderable

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Martin Miranda:
https://www.latticesemi.com/Products/FPGAandCPLD/MachXO2

asmi:

--- Quote from: nctnico on January 19, 2022, 07:46:29 pm ---The trick is to have the pads extend further away from the QFN package so you can reach them with a soldering iron. The recommended footprints are usually no good for hand soldering. During soldering use a big tip and lots of flux. The worst mistake to make when soldering QFP or QFN is trying to solder each pin. Instead, solder 3 or 4 pins at the same time (look up drag soldering).

--- End quote ---
No need for any of that. Simply pre-tin the pads, add some tacky flux, place a part and start heating with a hot air gun. It will probably take a few attempts until you master this approach, but once you do, it will become super-easy from that point on. Just make sure you keep your heat gun far enough to not blow the part away, nor to blow away neighboring components (you can protect them with a capton tape if you need to, but usually it's not required).

asmi:

--- Quote from: SiliconWizard on January 19, 2022, 06:51:04 pm ---I personally do not like QFNs. They are the most annoying to hand solder reliably, unless you can use a stencil. Just my opinion though, as apparently some people can handle them with one hand and eyes shut. ;D
--- End quote ---
Like I said above, just invest some time once into mastering this, and it won't ever be a problem for you in the future. Just get some cheap QFNs to practice if you don't have any already, and get cracking. It will only take a few tries until you get a hand of it.


--- Quote from: SiliconWizard on January 19, 2022, 06:51:04 pm ---As to the future of all this, having no crystal ball, I don't know. Is the hobbyist market going to disappear altogether one day? Are conventional PCBs going to themselves be obsolete (and replacement tech going to be completely out of reach for hobbyists)? Who can tell.

--- End quote ---
It won't disappear as long as there will be enough people willing to do it, which will probably never happen. The exact nature of it will likely change though, as the industry is trending towards miniaturization and ever higher interface speeds, so BGAs will become more prevalent as the time goes on.

Mario87:
Personally, I find the hand soldering of smaller / more challenging components to be some of the best part of a project. Maybe I am just strange like that  :-// :P

NorthGuy:

--- Quote from: asmi on January 19, 2022, 08:54:28 pm ---Just get some cheap QFNs to practice if you don't have any already, and get cracking. It will only take a few tries until you get a hand of it.

--- End quote ---

With QFNs, putting the correct amount of solder on the center pad is key. If you put too much, the chip will tilt one side and the pins on the other side will be left in the air. If you put too little, the solder on the center pad will suck the chip down and it won't self-align. It is easier to do with biggish QFNs (i.e. 20+ pins), but I often struggle with very small 0.4 mm parts.

If you use solder paste, you get better control of the solder quantity. In this case, QFNs are one of the easiest, way better than TQFPs. As stencils gets cheaper and better, solder paste becomes more advantageous than hand soldering.

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