SMD Soldering
 

Hey everyone,
I need some input on what type of iron I need to solder SMDs. At the moment I only have a standard iron from RadioShack that can switch between 15W and 30W. However, I have heard that irons with adjustable temperatures are far superior. I've also heard little snippets about hot air irons, but I'm very unfamiliar with these. Any links to store pages for recommended products would be greatly appreciated.

Re: SMD Soldering
 

Check out this video. It's got a pretty good intro into SMD soldering: http://www.youtube.com/watch?v=b9FC9fAlfQE

Re: SMD Soldering
 

This one: http://www.hakko.com/english/products/hakko_fx888d.html

You can get it from Amazon, SparkFun, or Adafruit.

It has enough power to apply heat quickly and efficiently, and still maintain tip temperature. Ideally, you want to make the connection as quickly as possible so that heat isn't transferred into surrounding components. I usually solder PCBs at 750F, and haven't had any problems so long as the iron has enough heat capacity. You can easily swap the tips out on the Hakko for fine point work, or something bigger for through hole or large gauge wire. This will be the biggest difference for doing SMD work.

[ninja edit]Skip the hot air rework tools until your proficient at SMD work with the iron. Do some research so you know what a good connection looks like, and what you need to strive for. Once you have some hand on experience, you'll have a much more intuitive grasp of how the heat transfers and what would be easier with a hot air gun. [/ninja edit]

Re: SMD Soldering
 

It'll be harder with a cheaper radio shack soldering iron, but not impossible. What package are you trying to solder? Some are easier than others.

The easiest way to do SMD soldering without great equipment (IMO), is to put a bit of solder on one pad on the PCB, then solder one pin of your component to the pad. This may take a few tries to get the component lined up. Next, put way too much solder over all the pins so that they're all shorted together but soldered to the pads underneath. Finally, reheat with your iron, and use solder wick to pull away extra solder. That's how I do it with a 15 watt soldering iron I bought for $7 from radio shack.

Re: SMD Soldering
 

The FX-888 is a tried and true iron. I like my Weller WESD-51. As long as you have something with good heat capacity and a temperature control. Good heat capacity is good for getting to packages with pads on then. Steer clear of ones that you plug in and change the tip for different temperatures. Those are pretty garbage.

Re: SMD Soldering
 

When it comes to soldering especially at the component level you get what you pay for in terms of irons. The adjustable irons are useful but doesn't mean they are good quality. In my opinion good tips are far more important especially with the small SMD components. Most of the Wellers from Frys or Digi Key can do the job, just be sure replacement tips are available. There are a few models with tips that are difficult to find. If your doing a massive amount of surface mount parts you should look in to using solder paste and a heat gun/oven (don't use your oven in the kitchen, once you use a oven for soldering you should never use it for food again).

Re: SMD Soldering
 

Ya, this is important too. I like the wedge tips for SMD work. The conical tips they usually come with aren't usually very good. The chisel tips give you more contact with whatever you're trying to solder.

Re: SMD Soldering
 

How pricey should the tips be? I just saw that the ones for the Hakko FX-888D cost around $10 or so. (2.4 mm chisel tip is $8.58)

Re: SMD Soldering
 

I've heard about doing this, someone called it a "Smash and Grab." However, I'm not terribly confident in my skills with solder wick, I haven't even had much practice desoldering with my pump. I'll get some more experience and try that eventually. :P

Re: SMD Soldering
 

I own one of these:
http://www.amazon.com/Aoyue-968A-Dig...dp/B006FA481G/

I bought it for my senior year at Purdue, which made doing senior design much easier since I didn't have to share this with other people.

I did 90% of the surface mount soldering and debugging (there were a handful of caps and resistors that another team member did). The temperature control is really nice, the hot air is superb (had many people asking me to help with their projects since what I had was nicer than most of the equipment in the lab), the smoke absorber is a really nice feature once you get used to it (the extra hose makes the cord a little less flexible).


The smallest thing I've successfully soldered was a 10 pin QFN with a footprint of about 2mm x 2mm using a reflow technique.

I've heard toaster ovens can also work if you don't have hot air..

Re: SMD Soldering
 

It depends on the name brand my Metcal uses $25-50 tips my weller at home uses $5 tips

Re: SMD Soldering
 

I own 2 WES-51's for SMT work. I use the 0.01" conical tips. You can angle the iron and grab the side of the part with the side of the tip. Make sure to get some water-soluable flux. It makes SMT work easy and possible.

For 2 pin parts, I like using 2 irons. Tin both pads first, and then apply flux. Then, grab each side of the part with an iron, and place the part in the solder. Done! Way easier than messing around

I wouldn't do SMT work above 700* F if at all possible. The higher the temperature, the more thermal shock on the board and the higher likelihood of damaging something. I own a board warmer http://www.mcmelectronics.com/produc...XncaAmOY8P8HAQ to pre-heat the board so the localized heating requirements are much lower, reducing thermal stress and making it a lot easier to solder harder parts.

Re: SMD Soldering
 

I've never done any SMD / SMT work myself, but folks who run a local hacker space do it all the time-- and they don't use a soldering iron:

http://tymkrs.tumblr.com/post/794649...nna-solder-smt

Re: SMD Soldering
 

The way we solder our RN42s down, you probably don't need any fancy equipment. We put some double stick tape on the bottom and generously apply flux paste. This method works great for lining up but you can't be too overeager with the solder as the tape creates a small gap that can cause shorts underneath the board. The most important thing with SMD soldering is having the component lined up properly. As long as it is lined up, you shouldn't have any difficulties.

Re: SMD Soldering
 

That is the normal cost for the genuine Hakko tips.

I actually just purchased one of these irons and let me tell you, after owning the one you said you have for years it was an absolute dream. You get fine temp control, a great iron holder, and tips that last, but the immediate difference I felt was the cord. Its extremely flexible, as opposed to the radioshack one, and will let you solder at whatever orientation you want.

Honestly I find soldering so relaxing now. Some people get a massage, I go into my basement and solder up a board...

Re: SMD Soldering
 

Dave give a very thorough explanation of how to solder SMD components.


With IC's, it works better to tack down two pins on opposite corners.

You can also get good deals from eBay on new and used temperature controlled irons. Look for Hakko 926, 936 or 937. Make sure you are getting the handpiece as well as the base. I find the newer Hakko's we have at work a bit flimsy.

An alternative to using the wire type solder is to purchase some solder paste that is loaded into a syringe. Make sure it comes with a plunger. Some of the solder paste syringes are meant to be used with automated equipment where the solder paste is pushed out by the machine. Squeeze out a tiny drop on each pad. Place the component on top of the solder paste and press down gently. The surface tension of the paste should hold the part in place. Heat up the pin/pad with the tip of the iron to melt the paste. Clean up with isopropyl alcohol (rubbing alcohol).

If you are going to be doing a fair amount of SMD soldering, you will eventually have to remove parts for one reason or another. It is easiest to remove two terminal SMD components using two soldering irons, one on each terminal (electric chopsticks). IC's are best removed by using two irons to "blob-on" enough solder to bridge all the pins on each side (as quickly as possible) and flicking the IC off the pads.

Re: SMD Soldering
 

Flux, flux, and more flux.

For either through hole or surface mount the key to good solder joints is heat flow.

One thing that can get in the way of heat flow is oxidation. Do you know what helps oxidation form? Heat, like all that heat in your soldering iron. That's why most solder that you buy is actually a tube with a goopy core of a chemical called flux. The flux melts as the solder melts and helps clean the joint of any oxidation, vastly improving the heat flow.

I've seen a lot of people "paint" with the iron. That is, flowing some solder on the tip of the iron, and trying to spread that solder blob onto the joint. This doesn't work because all the flux in the solder has already burned off and none is left to clean the joint.

This is why it is best to heat the joint with the iron and let the joint melt the solder. This ensures that the joint is at the proper temperature to melt and bond with the solder and allows the flux to do its job.

However, this is difficult for surface mount components. You need a third hand to hold the small component with tweezers in addition to the iron and solder.

Here is where flux paste or a flux pen comes in handy. First, apply flux to the pin and pad you want to solder. Then flow some solder onto your iron tip. Next, hold the part in position with some tweezers and paint the crusty blob of solder from your iron to the joint. The applied flux will magically breath life into that crusty solder blob and beautifully wick it on to the joint.

With lots practice, you can solder QFP packages in no time with plenty of flux and the drag method: https://www.youtube.com/watch?v=erb6-i54tbo

-David

Re: SMD Soldering
 

If you don't mind buying a used iron buy a metcal soldering iron (the ps2e power supply with hand piece and base can be had for around $100- $200 on eBay). The way the iron temperature control works is through the tip, so a brand new tip and you have essentially a brand new iron. The tips are a little bit more expensive (around $20 new) but you only need a few kinds and they last longer than any other iron I have uses.

As for soldering smd components just buy a good flux pen and make sure to use it. It will make a world of difference. Don't worry about getting a fine conical tip, as it will take forever to solder anything. You also won't be able to get enough heat down if you are soldering to ground planes. Instead buy a nice size (1/8") chisel tip and treat it with lots of care.

Re: SMD Soldering
 

I do soldering almost daily at work. The link below is what I use, I just picked up a second unit for the team this week too. Had mine for over 3 years. No problems yet and I still haven't had to replace the elements.

http://www.gqelectronicsllc.com/come...idProduct=4393

Re: SMD Soldering
 

For SMD parts, you could just make a reflow toaster.
Take a $20 toaster, a $10 Arduino clone, a $20 thermocouple, and a $10 relay. Or if you're cheap, a toaster and a seconds timer can work (although not as well as a real reflow oven will).

Re: SMD Soldering
 

I use one of these , it works great and usually comes with some extra tips. I like the soldering iron a little better than our Hakko F-888D and having the hot air rework is great for smd and other things like heat shrink, polycord welding .etc too.

We've also used a hot plate in a box to do some quick small batch reflow. Works quite well as long as you have a accurate thermometer to dial in temps.

Re: SMD Soldering
 

Honestly, I would shy away from the SMD toaster ovens. They're really just toys that kinda do the job. Heat distribution is terrible in them and even the metal grates you put them on can be disastrous. Plus, you still have to get stencils made, unless you want to try to put paste on the pads by hand (have fun with that).

Re: SMD Soldering
 

I have done the paste by hand. It's really not that hard for the standard types of smd stuff with legs and tiny resistors; just use a toothpick to apply. Unless you've got a ton of circuits to solder, in which case it makes sense to invest in a stencil.
I don't use the grate. I use a large metal plate that came with the oven, and that seems to do the job.
For stuff like QFN I would be worried about proper positioning, but you can hardly solder those by hand easily either.
I don't know about heat transfer, but I have done quite a few boards with my $20 toaster, including a sensitive high power LED board. With my shaky fingers I do not want to SMDs by hand (although I imagine it would involve a lot of cussing).

Re: SMD Soldering
 

This looks like a rather viable option. It also appears that the tips this unit uses are 900M (A rather standard size), so it would be easy to replace them.

Thanks for all the help so far, everybody! I never would have imagined that I'd get so many responses in less than 24 hours.

Re: SMD Soldering
 

I forgot to tell you, If you want free shipping, look for them on Ebay! Same company, same item.

http://www.ebay.com/itm/FULL-PACK-GQ...em3cc622 7884

Re: SMD Soldering
 

I find the most essential tool for SMD work is a good magnifier. I have used a binocular microscope in the past but I am using one of those dual magnifiers most of the time now.

http://www.mcmaster.com/#magnifiers/=va4pev