What I learned in Soldering 101
at BEST Soldering
Soldering is one of those black sheeps of the repair industry, viewed by many as a nearly insurmountable obstacle. No one really seems to be sharing what they know about soldering leaving many questions left unanswered. What is soldering? How it is relevant to my business? Where do I start? What are good practices? Is it profitable? The questions are many and that is understandable – especially with so many soldering YouTube videos where the application isn’t just what you are looking for, or the person who made the video just somehow miraculously finishes the job. Not to mention all of the, “How (not) to solder” videos that are out there. It is no help that more and more repairs are requiring soldering.
Here at eTech Parts we are anticipating seeing more and more soldering required on the next generation of the iPhone. Contacts in China aside, have you seen the supposed new rear housing for the iPhone 6? It is looking more and more like an iPod Touch every passing day. The most recent iterations of the iPod Touch have several soldered parts. If this is indicative of what to expect on the iPhone 6, the industry could be in for a steep learning curve to learn how to solder in a short amount of time to keep up with the repair needs of their customers.
In anticipation of that we have set up a strategic partnership with BEST Soldering. Well known in the manufacturing industry and playing a critical role in consulting and training, BEST has an established place as soldering professionals. In fact there is potential for BEST to be holding a hands-on training at CTIA for anyone who wants to learn about some specific solder jobs. I was lucky enough to attend the Soldering 101 training course at the BEST headquarters in Chicago. It was a great learning experience – one that this blog is dedicated towards. But looking through a microscope can be tedious work – and after nearly a dozen hours on the scope in two days you just need a visual break. For this reason before I go into great detail about what I learned I am going to share a picture that I snagged during my flight:
The most difficult soldering work I had done before this training was to solder a new headlight bulb socket into place in a very awkward Toyota Celica. I thought that was tough – but when I walked into the soldering classroom and was greeted with this setup:
My first thought was that I was in over my head. My classmates all had experience in the trade – up to twenty years on PCB (Printed Circuit Boards), leaving me as the odd one out. They were concerned mostly about through hole soldering, something that I had seen on the internet but never dealt with. This type of soldering would be the focus of the first day’s class. This is also a type of soldering that is mostly irrelevant to iPhones. The principles were great to learn if not exactly a perfect match to what I was looking for.
Let’s examine a bit of what we are looking at in the previous picture. The soldering station is on the right, it consists of a soldering iron, soldering tweezers and the power supply. We didn’t touch the soldering tweezers at any point during the training. As it turns out you have to take correct care of your soldering iron (or more specifically the tips). Good practice is to leave the tip covered in solder whenever it is in the iron stand. While it is hot this helps keep the tip from oxidizing, which can be cleaned, but it is easier to just leave extra solder on the tip. This is the same reason you can put a little extra solder on the tip and leave it during cooling. Speaking of solder – for our industry use lead-free solder and do not contaminate with leaded solder. If you have multiple applications and one calls for leaded solder, use a different tip.
All of our solder melts at some temperature below 350°C. You can probably make a strong guess about what my iron was set at for both days. Too low and the temperature transfer won’t be so great and you end up with “Cold Joints“. Which are bad – that’s all you really need to know. Too hot and you will break something, solder pads will lift, the board will get damaged, or the component you are working with. I found 350°C to be a happy temperature for my application. Your application and iron will probably be different so experiment to find a good temperature.
The other big piece is the microscope. Historically optics cannot be compromised on. They will be expensive. But that is mostly just my background in photography speaking. Cheaper and cheaper optics are coming out it seems like every day. But newer isn’t always better. Leica makes a good microscope, this one was pretty adjustable. Few things can bring you back to middle school as quickly adjusting a microscope – even though this one was incredibly clear. Soldering anything on an iPhone needs some kind of magnification. I learned quickly how big a difference a little bit of magnification makes.
Can’t have a good class without a good lecture. The curriculum and lecture from BEST were excellent. The class was small which gave the instructor plenty of room to spend time with each student working on their particular application. Admittedly spending hours talking about the basics of soldering does not carry the same level of excitement as riding a roller coaster – but you must have a realistic expectation of these things going in. Some of the topics covered at length were:
- Form, Fit and Function
- Risks of ESD damage (Including actual numbers. Did you know that the newest components can be damaged by as little as 4 volts of discharge? Did you also know that you will not feel a static shock unless there is 2000 Volts worth of discharge? Meaning you can easily destroy a device without ESD protection and not even know that was the cause.)
- Different classes of electronics
- The tip size of the iron (should be at least 50% of the pad size)
- The importance of cleaning throughout the process
- Letter designations of components
- Acceptance Criteria
- Identifying good and bad solder joints
The list goes on, but I won’t be copying all of my notes here. On most all of the videos I found online there is a comment along the lines of, “this is good enough.” Turns out what the pros are referring to is an actual standard in soldering. The standards are very rigid, the size, shape, and even texture of the solder, not to mention the leads can take what appeared to be a good solder job and make it into a bad one. This is where good optics come back into play, the high magnification makes all the difference for inspection which allowed me to identify my own mistakes. At first there were plenty. It’s a good thing no one’s life depends on my solder jobs.
Through Hole Soldering
The very first focus was on through hole soldering. This type of soldering is simple enough and does not really exist in our industry of tiny logic boards. The information was great, and the principles of soldering were well applied and taught. None-the-less it was still difficult to find a good application for the information. Or at least I thought. Almost immediately on my return I found a garage door logic board in my hands for repair and what do you know? It is through hole soldered. Good information will always turn out as an asset somewhere along the line.
The above board may not look familiar to you. When I first encountered it I thought it was something out of the ancient past – maybe 5 or ten years in technology time. As it turns out this type of board is still widely used in certain applications – like airplanes. Anywhere safety of a human is an issue you are more likely to see this type of board as they are in fact, much more dependable than the Surface Mount Devices (SMD).
Surface Mount Devices
Surface Mount Devices have become the standard in smart devices. The smartphone you [probably] own uses surface mount technology. The computer you may be reading this on uses SMD technology. Processes especially are apt to use what is called BGA (Ball Grid Array) mounts. The introductory class did not include BGA instructions but my instructor was kind enough to show me how to mount one during a lunch break. Much like everything else in soldering the key was to take time, use rework hot air, be diligent, check temperatures and ensure that the surrounding environment wouldn’t interfere.
The class was focused on soldering with an iron as opposed to hot air so that is where I got my hands on experience. This is the information that I had been looking for. How to replace a backlight coil on an iPad Mini? This was the information I needed on how to remove and replace that component. Knock off a cap while unplugging a LCD cable? No problem, this course helped me understand how to prepare the pad and replace the component. Want to make some quick cash by repairing a Samsung charging port? The information was all here.
Going from this board:
to this board:
Was not a challenge. I simply found the process that worked for me. It looked something like this:
- Investigate the target – What was my goal? Which component would go where and in what orientation?
- Ensure cleanliness – Dust the board and apply way more flux than I thought I needed (You can always clean extra flux later)
- Place small amount of solder on one corner pad
- Place the component, align as carefully as possible, and heat the solder – The component will sink into the solder and set on that one pad.
- Check for alignment and manipulate as needed
- Solder the adjacent corner
- Apply flux as needed on all other pins
- Add some solder to the tip of the iron
- Lightly drag the tip across the legs
- Clean the board with chem wipes, iso-alcohol and a brush
- Inspect – It is very important to inspect. It was common to have bridging, especially when I started. A Solder Wick removed the extra solder and with it the bridge
- Add/Remove solder where the joints failed my inspection
- Clean it again
One of the things about extremely detailed work is that it can prove to be mind numbing and even exhausting. In years gone by, I have worked at several different companies doing high volume photography. I always encouraged my fellow photographers and myself to be very intentional about breaking the mold. After 10-14 hour of taking pictures of the same thing the last thing you want to do is pick the camera back up. But it is needed. Picking the camera back up is a reminder of what we were passionate about, great photography. In a similar way, it is needed to step out from the view of the microscope and take a look around from time to time. With that in mind, I stepped outside on my lunch break for a walk and took this picture:
I know it is not a good picture but that isn’t the point. The experience was a great one and I am very happy to share my excitement not only as a technician but also as a member of the team at eTech Parts. It is eTech’s dedication to informing and enabling our customers what allowed this trip. As the industry grows, we are excited to grow along with it and will continue in our efforts to stay on the cutting edge and keep an eye open for anything that could be the next big thing. It is the repair community that helps guide us to the individual needs of our customers. So join the discussion, ask questions, share relevant information. As the identity of the community improves the idea of repair will continue to become more respected and well known, which means more business for everyone!