How to Solder SMD ICs the Easy Way!

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Introduction: How to Solder SMD ICs the Easy Way!

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While there are many How to Solder tutorials, there are only a few that cover how to mount some of those tricky small pitched ICs. These .65mm and smaller pitches can seem overwhelming at first, but with the right equipment or even just enough patients they can be soldered, and with practice quite easily at that.

There are several different styles ranging from using small conical tips, to solder paste and re-flow, to drag soldering, but we will just cover drag soldering in this tutorial.


Materials Needed:
Soldering Station -Weller, Hakko, or similar type that has a good range of tips.(NTGW gullwing or T18-C2 bevel)

Solder -If you don't have some good quality solder do yourself a favor and pick some up, it is expensive but will last a very long time.

Flux -depending on your style and the part that is being soldered this may vary and some may prefer a tacky type to a liquid, I am using a Kester 2331-ZX type flux pen.

Clean Wipes- If your flux is the corrosive type you will want to clean up after the IC is finished, use some nice lint free wipes.

PCB and IC to solder!

The steps involved are really straight forward, and once you get the hang of this technique you will use those difficult ICs in more projects! The only real steps are 1) Position IC, 2) Tack or affix IC in place 3) Solder each side or pin!

Step 1: Initial Setup

Now is a good time to take some initial steps which will pay off later in the process. Heat up your iron and prepare the tip cleaning method(distilled water w/ sponge or brass sponge) Tip maintenance is an important step in keeping your Iron and tips in working order and maximizing the use of them, it is important to keep it clean and when stored always keep a nice blob of solder on the working edges of the tip.

Start by cleaning, tinning, and then cleaning the tip again. This will make sure it is ready to go, with a "pure" surface that will transfer heat evenly and quickly. Apply a fair amount of solder on the tip  to keep it from oxidizing and place it back in the stand while we ready the rest of the steps.

First take one of the wipes and a bit of isopropyl alcohol and thoroughly clean the pad and area where our IC will be mounted. We don't want any dust, old flux or other contaminants interfering with our work!

After we have cleaned off the pads we can apply an ample amount of fresh flux, don't worry if it extends too much in any direction most will burn off and we will clean the rest in the last step!

Step 2:

Place the IC carefully making sure the pins are lined up as well as they can be, on some of the larger pin count packages this can be a bit difficult. In some ways this can be the hardest step. Once properly lined up tack a few pins or use a high temp adhesive like Kapton tape to hold the IC in place. Were now ready to solder it!

Start by tinning our tip, clean it and fill the bevel with a bit of solder. This "pocket" of solder will glide over the pins heating them and depositing the perfect amount of solder on each one. Because of the flux, surface tension and temperature differences the solder makes very high quality fillets that usually require no solder wick as the right amount is deposited at each transition.

The key here is to make sure the is enough solder on the bevel to make good connection, but not too much to over load the "pocket". Drag time should be kept minimal but there should be enough time for a wetting action to occur. A good initial time is about 1 second per pin but this depends on a number of factors, and can be sped up. But it is a good place to start at first.

As shown in the video fill the bevel, and drag down the pins at a steady pace, the key is to gently glide. The pocket and solder do the work not pressure from the soldering iron. You are essentially gliding over the pins leaving a tiny bit of solder behind on each one.

Now using the wipes and a bit of distilled water or rubbing alcohol gently clean the IC, pins and area around and took a look at your work! If you have some solder bridges you can clean the tip and re-drag, or use a bit of solder wick to remove the bridge, once you get the hang of it this is pretty rare.

I hope you enjoyed this and found it useful!

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    37 Discussions

    Your tutorial was perfect. At first I was skeptical it would be that easy. I was sweating over how to solder this FTDI chip to the Arduino board.

    Your steps were followed and it worked. I did have the first set of legs bridge in a couple of spots but some flux and solder wick solved that most quickly. The second set of legs worked as advertised.

    The only difference was on the second set of legs I dragged the tip of my iron across the very bottom of the legs right where they meet the pads.

    ftdi.jpg

    My soldering iron lights up my leds when i solder them, is that safe to use with an ic? is it just mine or every soldering iron does that.

    mine is.... well... a 4$soldering iron!

    2 replies

    $4 iron. Well, that may be the problem. If the case of the iron is floating with enough juice to light an LED then you need to get rid of it.

    Yeah i did buy a 20-10$~ one which can use different tips and has tinning, and ITS AWESOME! I can't call my old soldering iron a soldering iron :D I couldn't tin it no matter what, and it was a mess, but this one, with a slight touch to solder it just tins itself! Oh and i did easily solder an attiny13a! It was actually easier then a dip one (but smd led and resistors were kind hard ) but aftrr being done i accidentally droped a bulb of solder on the silicon part and my circuit doesnt work, not sure if my attiny is thr problem tho!

    Hey Yo!

    Drag-soldering. It is the easiest, fastest way and yields the best results of any type of SMD soldering. Now you are wondering where do I get these tips huh?

    Drag-solder, gull-wing, whatever these tips are called - there is the problem. I understand that there is an issue with the patent here in the US, so if you are lucky to find one of these tips, then you are going to pay thru the nose for it - am I right?

    Well - why not make one of your own? It's easy. All you need is a 2.5mm (shaft diameter) bevel-tip that you can buy online for a buck. You know - the ones with the slanted oval face on the end? Chances are, you already have one. You will also need a 2.0mm round burr for your Dremel tool.

    5-10 seconds hollowing out the center face of that bevel is all that is needed. You just need to make a nice shallow pocket in the middle. Then, fire up the iron and tin-it. You're done and you just saved yourself a wad of chedder. You are going to be so pleased with the results!

    One more thing: if you clear the pocket out of solder, the tip will pick up excess solder quite easily.

    Solder- use .2mm diameter solder. You will be amazed at the results with the right amount of solder.

    The wet sponge is OK but I prefer the ball of shredded brass. There is no thermal shock to the tip, the tip remains at temperature, does not smell, never needs cleaning or rewetting and it cleans the tip real good. The solder falls to the bottom of the holder and rarely needs cleaning. One could reuse the collected solder for their solder pot too.

    The flux pens can be pricy. Buy liquid flux in a small plastic bottle with a needle tip dispenser. You can never use too much flux. It spreads the heat and cleans up easily. This will not dry out, does not spill, is refillable, and last forever.

    Nice job, SparkyWidgets, by the way.

    Kim wipes can set you back 5 bucks or more. I wear glasses so I save my used lens wipes and let them dry. They are reusable, lint free, absorbent and they are free.

    Nice hand! The only other time I've seen this method used, the board was held in a vertical position and the solder was continuously fed to the side of the tip, while dragging back and forth. Very interesting.

    Question: I am under the impression that the "pocket" in the tip is essential for this method to work. You mentioned a bevel tip (the Hakko), which does not have the pocket. Am I mistaken? It seems very hard to find these tips; would you have any suggestion on where to get them?

    Thanks, Fabio

    1 reply

    See my post on easily making one of these tips yourself.

    It is easy. Go on ebay and find the SMD practice boards that sell for a $1 or $2 and free shipping. Buy several. It may take a month from China but they are well worth the trouble. They allow you to hone your technique before tackling the real thing. Surface mount is easy and I never thought that I would be able to say that. You need some magnification. I us 3X for working and then 10X for inspection. Good luck.

    Not so scary. I've been drag soldering like this excellent article shows for years with great success. If you do short a couple of pins, it's easy to clean up with a little flux and a clean tip. Also, it helps to get a 10x loupe to really inspect your work.

    All I can see SMT doing for a hobbyist is limiting their construction methods while increasing difficulties working with the devices. Not my idea of fun. Personally I avoid the stuff like the plague. So far that has been the best technique for me to employ in regards to SMT.

    So color me not interested as I leave SMT to the pick and place machines it was designed for.

    2 replies

    It really is up to each person and their preferences. Having said that,
    I think any tools, methods, or knowledge that can make "hacking", hobbies, software or other activities like this more accessible are a great service to those interested. After all that is what this site is all about, limiting would be to simply shrug this off when it can clearly be done, and quite easily at that.

    (On a side note a DIY PnP to an oven similar to a production line would be sweet! Someone make this project/instructables!)

    Well I am an electronics hobbyist and I voiced my opinion on SMT. I do have an axe to grind with it as I have seen it gut my pastime into but a pale shadow of its former glory.

    You mentioned it so I blame you! Which likely isn't fair, but who ever said life was fair?