Hand-soldering Teeny Tiny Chips!

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Introduction: Hand-soldering Teeny Tiny Chips!

About: currently a graduate student at the MIT Media Lab

Have you ever looked at a chip that's smaller than your fingertip, and has no pins, and wondered how you could ever possibly hand-solder it? another instructable by Colin has a nice explanation of doing your own reflow soldering, but if the your chip is not BGA, and you want a technique that's quicker and won't put as many poisonous fumes into the air, read on...

p.s. here's what you need:
- soldering iron (fine tip)
- microscope (or very, very good eyesight)
- some flux will help (flux pen)

Step 1: Check Out the Chip

Make sure you know which orientation the chip is supposed to go on the PCB. In this picture, you can see the little dot to the left of 'CYG'. The convention for chips is that that the little dot indicates the top-left corner of the chip, and you can have a look at the PCB layout diagram to figure out how the chip is meant to be oriented on the board.

Step 2: Tin the Pins (and Maybe the Pads)

Turn the chip upside-down, and melt a little dab of solder onto each of the pins. You can do the same for the board too, if you want. Make sure you heat the metal of the pad enough to melt the solder itself, rather than melting the solder with the tip of the iron directly. After you tin all of the pads, use a flux pen to put some flux onto the board where the chip will attach.

Step 3: Put the Chip in Place

Turn the chip right-side up, and gently nudge it into place with a pair of tweezers until it's centered on the spot where it belongs.

Step 4: Connect Top to Bottom

Now comes the fun part. One by one, you need to heat the balls of solder that you've created, so that they become connected to the chip *and* the board. You can do this by touching the pads/pins from the side with the soldering iron tip, and sometimes wiggling it up and down to encourage a connection to form. A nice trick for the first pin that you solder (can be any pin, it doesn't really matter which) is to hold the chip firmly in place with a pair of tweezers (pin it down to the board), and touch the hot iron to the pin/pad in one corner until the solder bridges the gap. With any pin, you may need to wiggle it up and down, or add a little more solder (see the picture) to get it connected. But don't add too much, or you risk bridging pins underneath that shouldn't be bridged. With even just one connected pin, the chip will be stable enough that you can do the rest without having to keep it pinned down. You can work your way around the chip, connecting each pin to the board until you've got them all. See the next step for how to make sure you've connected everything successfully.

Step 5: Check Your Work

Now you can tilt the chip up on and look at the connection points, to see if you've made all of the connections successfully. Zoom in enough that you can see if the solder is going all the way from pin to pad or not. For the ones that are not, add a little more solder to the pad and wiggle the iron up and down until you get it to bridge, like a stalagtite meeting a stalagmite.

Step 6: Go for It!

Once it all looks good, give it a try! With a microcontroller, the first thing to do is to try programming it and see if it responds. From there, you can test if it can interact with the things that it's connected to (LED's, sensors, actuators, etc). Happy soldering!

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    48 Comments

    My dremel versatip gas soldering iron just won't let me melt things with its tip. I dont know, but no matter what I try, the tip just wont melt things, and solder doesn't stick to the tip too, but rather further down the tip, which is useless for me...

    My mainboard look bad, any chance to fix this ? heat gun doesn't work here as you can see my joint is made frm plastics.

    DSC03846.JPG

    I prefer to presolder the chip (Like you did here), but then after the positioning (and securing), ill take my heatgun, set it to 410°C and quickly solder all points down in a few secs. No additional solder is needed and the result is much less excess tin around the pads.

    I succesfully soldered this way down to 0201-sized SMD-Items. Havent had to solder 01005 (Fortunately) but who knows...

    Anyway: Your instructable is nice and explains the process quite well and also does note the important part of checking the solderpoints afterwards.
    Nice instr.!

    4 replies

    Wouldn't the use of a hot air gun be detrimental to the chip? (obviously not, as you have used it) Whenever I use mine for whatever task (shrink shrinktubes, bend plastic) it will burn stuff very very quickly.

    Hot air gun is the right translation I think :-) I just call it an 'Hete lucht pistool' :-)

    My Hot Air Gun is not a cheap one with only ON/OFF but with a digital part with sensor and stuff. Costs over 100 Euros.
    You can set the temperature and air-flow and oh-boy does it regulate the temperature well! We measured it against a calibrated PT100 and it came out in just around 2% error. Not bad!

    See 2nd image @ Amazon: http://www.amazon.de/STEiNEL-Hei%C3%9Fluftgebl%C3%A4se-HG-2310-LCD/dp/B000UXBMVS/ref=sr_1_1?ie=UTF8&qid=1349882910&sr=8-1

    The trick is to set the temperature to just a few degrees above the melting-point of the tin or paste you use.
    Normal Chips can witstand such temperatures without any problems for quite some time... I once tripple-re-Soldered an FRAM tis way... Took 5 Minutes of hot-airing in total for sure. No problem at all for the Chip...

    I like the sound of a heat gun. Do you use a pencil style heat gun, or can a regular size heat gun work? Just blast it for 5 secs?

    Unsure what it is called in english... Native swiss guy here speaking german ;)
    I use this one: http://ch.farnell.com/steinel/hg-2310lcd-eu/heissluftpistole-230v-eu-lcd/dp/1712315 which is with 330 swiss francs a very expensive one...
    Cheaper ones also work no problem... But i like the option to regulate the temperature to degrees and not only with "1-10" and also being able to adjust the airflow independent from the rest...

    So yes: Large one; not stylus-type like http://ch.farnell.com/oki-metcal/hct-900-21/heissluft-loet-entloetstation/dp/1015504 as an example.

    Heatgun may NOT be the term you use... In german it is "heissluftpistole".
    Heissluft = hot air / heat
    Pistole = handgun / gun
    So heatgun seems to work... Also wikipedia knows it with this name:
    http://en.wikipedia.org/wiki/Heat_gun
    "They are also used in electronics to desolder circuit board components" is even listed in the wiki! :) And also there is a citation needed.. Maybe they want to link to here? ;)

    Great Instructable, terrific photos! Thank you.

    I like Caig Labs Circuit Writer, a pen-shaped dispenser that places a small dab of conductive glue that dries hard. For tiny connections, transfer it with the tip of a straight pin. No worries, no shorts, no heat. Clean surfaces, but flux is probably not needed. About $20, check Froogle.com

    I've used it to place surface-mount capacitors, resistors, etc. directly to the pins of mini-DIP IC's and create power buss traces on the case, so I make tiny projects with no PC board, then encapsulate with clear epoxy or hot-melt glue. Use 40-ga. Kynar or "wire-wrap" wire for jumpers.

    For a tiny solder pencil tip, file a piece of solid wire to a point and hold with pliers and wrap it tightly around the tip, then tin the wrap and the point. The common copper wire used for electric outlets is handy.

    If your eyesight is lacking, try a pair of "readers" eyeglasses at any drugstore for a few dollars or get a set of magnifying glasses on a flip-up headband.

    For a steadier hand, hold tools closer to the work, same as you were taught to choke-up on a baseball bat to improve control. Also hold your hand against a solid surface, same as steadying a camera.

    The "ground" shown in the center of the chip above also acts as a heat sink, so heat will determine its need. Digital circuits rely on solid supply voltage and reliable ground. If either is the least bit flaky, odd results will occur, so make sure both are solid.

    I had a chip have crack issues on the joint/trace junction etc. I found that by using a flat nose 30 watt iron I could flow solder over all traces. some became joined but that is ok because your only half way there.

    Take a piece of solder wick and lay over a line of connections. have a slight film of flux on your wick. heat it and any solder not attached to a trace/connection will be removed by capillary attraction to the wick, leaving nice chip to joint attachments. remember to lightly use some alcohol to (read Q tip) to remove excess flux as sometimes I can make a chip act funky.

    I have a different technique. I first apply some solder on 1 PCB trace, let cool. Place chip with a bit of downward pressure, make sure it's aligned, melt the solder. Then i just take advantage of capillary action and melt the solder on the traces and it'll just go to the pins. Too much=short though. Alot of flux helps.

    my friend said that he had a chip smaller than his thumb,I shoulda believed him!

    1 reply

    Many chips are smaller than a grain of rice these days. Open up some broken electronics made in the last 5 or 10 years, I doubt you'll find chips with actual through-hole leads.
    It's rather irritating when your parts *require* a custom etched circuit board to even be used.

    wow that is small hey could i make a robot that small hmm i wonder

    There is one huge problem with your method. You put solder on each pad, which has thickness. Then you melt only one pad, when you do this all the other pads will keep that one pad from properly seating. As a result the entire chip will not be seated properly. If you could heat all pads at the same time, then this would work.

    What I do is put solder on only one pad, then solder down that one pad. Then I head each trace and have the trace melt the solder. This will cause the solder to wick-up onto the pad. This way all the pads are properly seated.

    I like your ideas of using the Flux marker, I didn't know these existed.

    -Matt

    Thanks for the good tips. I have never done anything before............I am starting out doing whatever I can do with electronic stuff, because I started with PCs...um, this is my project and after reading your post I may have a go at this 3rd generation ipod headphone to motherboard connecton repair job. Tricky because the wires on the "board" part are torn from the chip pins.

    Picture 162.jpgPicture 158.jpgPicture 161.jpg

    I needed a chip that small -- I was building a little battery powered ring that could communicate using infrared, so everything had to be tiny!

    NO need for steady hands. Just get some Masking Tape and your set. Use a razor to cut a long thin strip and place over half the IC and then solder a few pins and remove tape and continue the rest.

    Nice! Doesn't really address the major problem, though, and that's the requirement of VERY steady hands...

    2 replies

    yeah, you might want to avoid having too many cups of coffee on the morning that you're doing this!

    Take some dramamine before soldering (or dissecting tiny critters). Will steady your hands right up. lol People have been know to use this tactic to fool lie detectors as well. though at larger intake levels.