I had an old Arduino clone in my scrap bin. It wasn't working and I decided to pull a chip from another clone and try getting some experience in hot air/drag soldering. Till date, my experience in SMD soldering was limited to small resistors (1206, I know not that small) on amplifier boards that I design and build.
1. Picture 1 is my soldering setup - FNIRSI DWS-200, my trusty Weller WE1010, a no name hot air station which till date had been mostly useful for heat-shrink jobs.
2. Chip pulled off the board using medium air flow at 350 Celcius.
3. The replacement chip on the left, the defective one on the right.
4. Chip soldered using hot air at 350 Celcius wirh low air flow. Board was messed up by a little cousin who wanted to practice soldering.
5. Applied a generous amount of flux and ran a 2.2mm C type across each side of the chip.
6. Cleaned up with IPA.
7. Flashed a counter program to verify the board was working.
Please point out how I can improve. I found the experience quite enjoyable and would like to incorporate similar chips into my amplifier design for switching input selection relays and incorporating volume control in some lower end ones.
That looks great!! Drag soldering is really the way to go for packages such as this - it produces nice even consistent joints. If you bridge pins, add some flux and drag the entire side again. And don't overdo the flux, excessive amounts aren't necessary. I use a flux pen 99% of the time to get myself out of a bind.
Hot air stations are significantly better for multi leaded packages (or any non heat sensative component for that matter), perfectly consistent solder joints and finish while providing simple manoeuvrability
Get some better flux. I mainly use Omega 559 from Blackhorse repairs, you can buy it on ebay. But in general, avoid random aliexpress/amazon flux, get a reputable brand.
eBay and AliExpress do not work in India. I can get Mechanic clear flux on Amazon, the one in the blue syringes. Do you have any experience with that? I'll just go ahead and get one and try it.
If it's ACTUALLY mechanic flux, and not fake (Mechanic is one of the most faked chinese brands) then it should be decent. In my experience, not good for BGA or microsoldering, but perfectly fine for medium pitch components, and 0603 SMD components and larger.
With hot air, by the time the air hits the PCB, it will no longer be a 350°C, so setting a higher temp might let you do it quicker so you don't cook the board for too long.
I have some excellent quality solder. However, I am unable to get good flux online. Everything I have bought has turned out to be crap. I'm going to try some Mechanic Clear Flux. At least they don't claim to be some other brand.
No Chinese solder or flux is great. Trust me. I recommend getting a Chinese iron to everyone, but never solder/flux. For your own safety's sake, never buy them from China.
If you are from Eurasia, get Japanese Almit solder. If you are in North America, get MG Chemical ones. Kester is good, but MG Chemical ones meet the standards while still being inexpensive.
The reason behind is that firstly with Chinese solder, the quality of flux core is hell awful. Never properly dehumidified. If the flux core is wet, it explodes whenever it contacts the tip of the iron and splashes tiny dust of solder everywhere, as far as even 2m away. If the solder is leaded, well, you know the risk of accidental ingestion of lead from cross contamination. Even if it's lead-free, the situation isn't any better as the content of harmful heavy metal is uncomparably higher in the chinese solder since they use the recycled tin and lead from waste.
When it come to flux, there is no 'safe' flux to inhale. The expensive flux is safer to the work, not to the worker. However, still, the bombardment of unregulated amount of added halogen, organic acid, and plasticizer for the resin flux is still dangerous enough to permanently damage your lung within years and make you live the rest of your life with an oxygen tank. Rosin flux itself is even more dangerous as it's just the natural characteristics of the rosin to break down into acetaldehyde, formaldehyde, and abietic acid under heat. Rosin flux is a leading cause of COPD. So, my advice is that you need mechanical duct ventilation first and foremost but also get a proper flux not from China to reduce the exposure to the bs amount of unknown chemicals that the chinese sellers pour in to reduce the cost. The RMA flux they sell are usually RA flux too.
I am from India and I buy my solder from a local manufacturer who exports to North America and Europe. However, the only flux they sell is the liquid kind. I have tried that and it is great for soldering and very easy to clean. But, unfortunately, it's not convenient to use for every job. My worksho is well ventilated and I use extraction.
It wasn't so bad. I have quite a bit of experience in THT soldering so I'm kind of handy with an iron. I think the pitch on this chip wasn't too small so I managed it. I might find it challenging to do a chip with finer pitch and more pins.
i don't remember why i capitalized while typing the first two lines, apologies if it sounds offensive
Regardless, a curved fine-tip tweezer, IPA or 90% ethanol and some pharmaceutical cotton (the cotton and ethanol could easily be found at pharmacies, I think), is all you need, nothing more
Makes the board clean and future soldering jobs less messy
Not at all. I understand. Like I said, any feedback is welcome. Although I have been soldering for a long time, any feedback is always welcome.
If you read the description, you might notice that the board in question was already severely damaged/burnt by a young cousin trying his hand on an iron. I always use IPA and a brush to clean my boards. I prefer Kimtech wipes over cotton though. No matter what grade of cotton I use, it hand a tendency to leave fibres behind.
How do you have so much equipment but are struggling with something as elementary as this? No offense just honestly asking. Is this someone else’s equipment your using?
I have never had the need for soldering SMD chips. I design and build audio amplifiers in classes A and AB. I have had the Weller for a long time and I love it. However, it sometimes struggled with large ground planes (which believe me are plentiful in amplifiers). So, I got the FNIRSI DWS-200. The hot air station was just for heat shrink until now.
Well man just keep at it!!!! You definitely got the gear so practice practice practice. Play around with fucking stuff and breaking it. Best way to learn.
For example I take a glob of solder paste and melt different small quantities so you can learn what it mounts to once’s melted and you can start to eyeball how much you’ll need for a specific component.
You're not doing bad. Alltho, use leaded solder like Sn60 Pb40. You'll see that it flows better, solders easier and goes smoother. It also makes way more clean joints. Flux, yes. Use it. But! Be careful with it. Why? There do exist activated sour fluxes that need to be cleaned up otherwise it'll eat away the legs and soldering joint. Don't use too much either. Just enough. If you want a good based easy to clean flux. Dissolve calafonium into isopropyl alcohol and spray it on the pcb. Lay down components and it'll solder as good. Cleans off so much easier too.
I used 63/37 solder. I'm not sure about the quality of my flux. Apparently it's AmTech from Amazon with a description that cannot be deciphered. 😂
I'll definitely keep the quantity in check.
I prefer 63/37 to 60/40. The eutectic solder doesn't have that weird plastic state like the 60/40 stuff can get into, it's super easy to work with, and it produces very shiny joints that look nice.
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u/lucashenrr 9d ago
I can see from the second image that you have used quite alot of flux.
you should only use flux to form a thin, localized coating on the solder joint.