Instructables
Picture of How to Solder SMD ICs the easy way!
INSTRT2Pic1.png
INSTRT2Pic2.png
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!
 
Remove these adsRemove these ads by Signing Up

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:

Picture of
INSTRT2Pic11.png
INSTRT2Pic12.png
INSTRT2Pic13.png
INSTRT2Pic14.png
INSTRT2Pic15.png
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!
trussell151 month ago

You made that look so incredibly easy! Trying to do one pin at a time is a nightmare.

Been soldering my smd's one pin at a time - going to try this next time.

SparkysWidgets (author)  throbscottle1 month ago

This will definitely make soldering easier, when I first started (I used to make some USB/serial to 7816 interfaces hand etched etc...) I would do it one pin at a time and it was just a PIA, ever since I learned how to drag solder and reflow solder life has been much easier! P.S keep an eye on my channel over the next couple days for a couple new videos!

tarun311 month ago

I had a small doubt. Won't gliding over the pins like that cause a short between two pins somewhere in between unknowingly?

SparkysWidgets (author)  tarun311 month ago

Usually not especially if there is proper soldermask and flux usage. But it can happen on milled copperclad without enough flux for example.

Wow, you make that look so easy!
Thanks for giving me the confidence to try something new :)
Dodge2 years ago
This is great.
Now I have a use for all the smds I stripped off scrap boards over the years. Thank you.
pfred22 years ago
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.
SparkysWidgets (author)  pfred22 years ago
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?
Jayefuu pfred22 years ago
Sounds like you just need more practice :) I go for the solder paste and heat gun method personally, nice and easy and there's no chance of knocking the chip while you're soldering.
pfred2 Jayefuu2 years ago
Why would I want to practice doing something I've zero interest in?
Scucci pfred22 years ago
I'll give you one thing... it does make some jobs harder. I've even lost actual paying jobs because I'm rubbish with SMT soldering. Big plant here, that has pick and place machines... still required people to be able to hand solder (quickly, and at the same quality level as the machines) SMDs. I'm not to that level yet, and probably never will be.

BUT, on the other side... there are some things I do like about SMT. If you're getting boards made for your projects and you want to limit the size of the board for price reasons, it's hard to beat surface mount. While a board with only through hole parts might be 30x30 (usually above the price break size from hobby level manufacturers), you can easily squeeze that onto a 10x10 or 20x20 board, which are much cheaper. I'll use through hole and perf board for protos... but when I need to get a few boards made, I'll usually swap to surface mount just because it is so much cheaper for me.

It is a trade off though, the extra effort you have to put into the surface mount parts versus the additional cost of through hole components and the additional costs of boards being made larger for those through hole parts.


As far as gutting the hobby... I'll always blame the ex-hobby shops like Radio Shack for that. When I was younger I used to be able to walk into RS and they'd have 2 full isles for just components. Peg after peg of at least the basics. Now it's all cell phones and iPod cases... the parts are in a little parts bin in the back and it's always out of stock of anything useful (who doesn't have at least a few 555's, I mean... come on RS...). I have to get all my parts from online places now (at $5 in shipping for each little order) and while I know my way around sites like DigiKey and Mouser, they do confuse some of the newer people and that can/does frighten some people off. ... /rant
pfred2 Scucci2 years ago
I'm a DIY electronics hobbyist so I don't ever send boards out to be done for me. It is rare I ever need more than one of whatever I make. I only do it because I enjoy doing it too. I think I may have the Mr. Wizard gene or something. I also pursue electronics as a hobby because it is usually low to no cost for me to do. Nothing thrills me more than to make a project 100% out of scrap I've scavenged. For me that is the holy grail of electronics. Total junk box projects.

Don't blame Radio Shack. They had to adjust with the times. Everyone else didn't and they went out of business. Long ago everyone could see a tube glow and they knew it was working etc. But things have miniaturized so much today that electronics is simply too abstract a subject for most now.

It is hard to be too interested in what you cannot even see.

I just paid $46 to get 2 10 mm capacitors shipped to me. Granted I didn't have to pick overnight, but I was in a rush to get them. Was Mouser in case anyone is wondering. I needed them to repair my TV. For what it cost I almost could have had someone else do it for me though.
fagnelli2 years ago
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
Awesome instructable! I have been soldering for years, and this is the best explanation of drag soldering I have seen.
dafonso2 years ago
Good job. Drag soldering is almost always the way to go.
ac1D2 years ago
Thanks you very much for this method. I used to solder each pad one by one, yelling every 5-6 pads when something went wrong.
I sure will give this a try ;-)