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Topic: soldering a QFN23? (Read 764 times) previous topic - next topic

vasquo

I have a need to use a chip but it's only available as a QFN chip.

Does anybody have any tips for soldering a QFN23 chip?  Can this be done in-house (without sending the board for professional PCB Assembly).
What method did you use?
How did you apply the paste? Can you just run solder paste bead across the pads? or did you use a template?
do I need a reflow oven for QFN chip soldering?

The smallest part I've tried is a SSOP-28 (hot air + solder paste).

Zapro

I guess you mean a QFN32, since i've never heard of a 23-pin device ;-)

Have a look here:

http://www.youtube.com/watch?v=c_Qt5CtUlqY
http://www.youtube.com/watch?v=M_rO6oPVsws
http://www.youtube.com/watch?v=d-f-SBC0GrU

// Per.

CrossRoads

I think your best bet is paste &  hot air.

This place has stencils for all kind of chip sizes, I have stencils for 28-pin FTDI chip, 32 pin ('328P)-44 pin (1284P)-100pin ('2560) TQFPs, and maybe a couple of others, or maybe just those 4.
http://www.proto-advantage.com/store/

I don't see QFN-23, are you sure that's the correct #?
Maybe QFN-32? Will need to know the pin pitch & body size too.

http://www.proto-advantage.com/store/advanced_search_result.php?keywords=qfn-32
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

vasquo

Ahhh... thanks!  No wonder I didn't get any results from Youtube when I searched for QFN23!  :smiley-mr-green:

Yes, I meant 32.

dc42

Use solder paste and either hot air or a hotplate. There are plenty of tutorials about both.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

JoeN

Schmartboard makes breakout for QFNs also.  See this video for how they do it:

http://www.youtube.com/watch?v=lKahRk9-uB4
I have only come here seeking knowledge. Things they would not teach me of in college.

jonisonvespaa

#6
Dec 26, 2012, 03:20 pm Last Edit: Dec 26, 2012, 03:21 pm by jonisonvespa Reason: 1
i used to solder thousands of 200 pin sm ics, used to use a hot air gun and tweezers and to position the ic, then cover all the pins with a small paint brush with flux, then go over the pins with just a soldering iron no solder, just using the solder/tin from the pins and the pads, if they look a bit dry then add a very small  dab of solder

try using a gently heat from hot air gun first else you will burn the board.

MarkT

The other approach is to have a solder stencil made - then you need a way to hold the stencil under tension on the board
and squeegee the solder paste onto the pads - place component, hot air or a toaster oven...

The tricky bit is the stancil mask holder/frame - expensive commercially, can be made if you have suitable mechanical
construction skills though.  Some PCB houses charge for laser-cut stencils, some throw them in as part of the deal.
[ I won't respond to messages, use the forum please ]

dhenry

1) glue it belly up.
2) use thin wires - I use those tiny strands from speaker cables - tin the wire and put some flux on the pads.
3) put one wire on a pad, and a quick touch of the solder tip will do.

If you like, you can glue it to a dip adapter so you can use the whole thing as a dip chip.

JoeN

I just soldered a QFN32 ATTiny88 on a Schmartboard DIP adapter (this one: http://www.schmartboard.com/index.asp?page=products_smttodip&id=460).  It works fine.  I didn't check every pin but it looks perfect under the microscope and I know the 2 grounds, 2 VCCs, and 11 other pins are working no problem, first time.  It's actually amazing how easy it was to do.
I have only come here seeking knowledge. Things they would not teach me of in college.

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