Although not the cheapest, ebay is probably the easiest way to find faulty systems.

Some equipment recommendations:

• A TS100 soldering iron. I use a more expensive Hakko FX888-D, but I've heard great things about this one for the price. Try to get a chisel tip for general purpose use, it has a balanced combination of size and heat transfer.
  
• iFixit 64-bit toolkit, for handling all the various screws you'll encounter.
  
• Soldapullt desoldering pump. Don't bother with the Chinese knock-offs, they seem to break easily.
  
• Fine 63/37 solder. One roll will last you a long time. Don't bother with cheap Chinese solder, it will not have the advertised metal composition and give poor results.
  
• I like this flux, but it's kind of pricey.
  
• Desoldering braid is essential.
  
• Neoteck multimeter. Very good for the price.
  
• If you need to remove SMD components, a 858D hot air station available under various Chinese brands you've never heard of. Kind of sketchy, but works and has not burned down my home yet.

Build Log 5: Viterbi

Highlights

• Viterbi split ortholinear 70 key keyboard from keeb.io
  
• Kailh Pro Purple Switches from NovelKeys
  
• DSA Honeywell Keycaps from PrimeKB
  
• Socketed Pro Micro controllers
  
• First personalized QMK keymap!
  
  

  Parts List
  

• 1x Viterbi PCB Kit
  
  • 2x Viterbi PCBs (Rev 1.0)
    
  • 2x Push buttons for reset
    
  • 2x 4.7kΩ resistors
    
  • 2x TRRS jacks
    
  • 78 1N4148 diodes
    
• 70x Kailh Pro Purple Switches (Tactile 50g)
  
• 1x Black PCB Viterbi Plate
  
  • 2x PCB swtich plates
    
  • 2x PCB bottom plates
    
  • 16x M2 6mm screws
    
  • 8x M2 11mm standoffs
    
  • 8x adhesive bumper pads
    
• 1x Silver Sheathed TRRS Cable
  
• 1x DSA Honeywell Keycaps
  
• 1x Red Rubber O-Rings
  
• 2x Pro Micro (ATmega32U4)
  
• 4x Mill-Max 12 Position Ultra Low Profile Socket
  
  

  Resources
  

• Nyquist Build Log
  
• An Overly Verbose Guide to Building a Let's Split Keyboard
  
• Socketing a Pro Micro
  
• A Guide to Flashing a Let's Split for Beginners (Windows)
  
• Build Log 1: Nyquist
  
  

  Tools
  

• Hakko FX888D-23BY & Flush Cutters
  
• Hakko T18D16P Tip for general purpose soldering
  
  • The tip that comes with the FX888D is either this tip or one that is extremely similar.
    
• Kester Rosin Core Solder (63/37 .020)
  
• XOOL ESD Tweezers Tools Kit
  
  • ESD-15 for most work, especially inserting the wires during controller socketing
    
  • ESD-34A for desocketing the Pro Micro controllers after they've been socketed (as a pry bar under the controller and then as a wedge between the underside of the controller and the top of sockets)
    
• Engineer SS-02 Solder Sucker
  
• NTE Electronics SW02-10 Solder Wick
  
  

  Notes
  

• The Viterbi build process is pretty much the same as the Nyquist, with the addition of 10 keys. The other difference is the placement of the two resistors, which now are only installed on the master side (the side with the USB cable, the left hand side).
  
• When flashing, I wasn't able to find eeprom files specifically for the Viterbi. I instead used the eeprom files from the Nyquist and everything seems to be working so far.
  
• Some of the keys are a bit crooked... I'm not sure if this is the switches themselves, or me somehow soldering the switches crooked.
  

This is highly recommended: Kester 44 Rosin Core Solder 63/37 .020 1 lb. Spool https://www.amazon.com/dp/B00068IJWC/ref=cm_sw_r_cp_api_Tn0vybNY3QZ01

And if you plan more than one project this soldering iron is great: Hakko FX888D-23BY Digital Soldering Station FX-888D FX-888 (blue & yellow) https://www.amazon.com/dp/B00ANZRT4M/ref=cm_sw_r_cp_api_Bo0vyb4YNQS1G

Do not use that solder.

Do not use that solder iron.

I use 63/37 resin core solder mostly.

I use a Hakko FX888D (also get T18 compatible wedge tips).

Try this solder. I am using a thicker solder now, but I am going to switch to this one probably.

Some more advice: the wattage you use with cheap soldering irons like that depends on many factors. Do not focus on the temperature/wattage alone. What you want is to get the contact hot enough within 2 seconds to form a good joint. So, touch the iron, two seconds, touch solder, immediately wets and forms the joint (and you remove the solder and iron as the situation dictates).

My recommendations, and what I have used for a long time. Really don't go super cheep on your iron, you will regret it:

Weller WES51

Long Conical Tip Really necessary if you are going to be building things with small components.

Kester 44 Rosin Core Solder 63/37 .020 the link is to a full pound which you might not want to spend the money on right away. The price seems to have doubled in the last 3 months at amazon for some reason. But plenty of places sell Kester Solder

IMO you can use whatever iron you want, but spend money on good solder. I like Kester 44 63/37. 63/37 means 63% lead, 37% tin, which is the "eutectic alloy" for solder. That means it's the lowest melting temp you can achieve (less heat on the joints is a good thing), and maybe more importantly, it melts at one precise temperature, while most solder melts at a range of temps, and within that range it is a kind of goopy solid that's hard to work with. 63/37 totally alleviates that scenario.

Kester 44 is great in particular because it has a huge rosin core which means a lot of flux on the joints, which lets solder flow into the joint easily and avoids oxidation.

Oh shoot! Thanks for reminding me, I was at work when I responded. I use this https://www.amazon.com/gp/aw/d/B00068IJWC?psc=1&ref=ppx_pop_mob_b_asin_title

It's 0.02" not sure about mm sorry Dx

This is what I use.

Yeah, that would be alright. An unregulated iron would get way too hot, so having any kind of regulation makes all the difference. With one of those irons, I would use an official Hakko T18-S7 tip, this solder, a flux pen, and some 99% isopropyl on q-tips to clean up the flux afterwords.

The temperature you want is as low as possible but still hot enough to melt the solder pads as soon as the iron contacts. Somewhere around 330C. When you're doing a hard mod, you don't want to make contact with the iron for more than a few seconds at a time or you could start melting off SMD components around the pads. Allow the board time to cool between wires.

To contradict OP, almost anyone can do a hard mod with the right equipment and technique. It's basically cheating with the above setup. People who botched theirs had to be doing things very wrong.

I agree here. If you can spring for some "good" stuff, Kester 44 Rosin Core Solder 63/37 (in your diameter of choice) is my go-to all purpose solder, and a 1lb spool lasts a really long time.

Also, some rework flux is good for fixing mistakes. I can personally recommend ChipQuik

Unless I specifically need solder paste, I can do anything with those two products.

This stuff, Kester 63/37, 0.20 inches, is pretty perfect for small fiddly stuff without being too thin to use for through-hole soldering. The 63/37 mix is eutetic which is a fancy way of saying that both the tin and lead melt at the exact same temperature.

For flux, you won't regret getting a flux pen, for example something from SRA soldering or MG Chemicals.

This low temperature solder paste is interesting, also. It is lead free, and melts at fairly low temperature. In fact I think this is the same alloy also sold as 'Chip Quik'. Even if you only have a soldering iron, assembling boards can be quite a bit faster with solder paste. And hey, a hot air station is only like 50 bucks.

Continuing this thought process, I just got this iron and [this](
https://www.amazon.com/gp/product/B00068IJWC/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1) solder in the mail the other day and they've treated me incredibly well. If that's out of our price range then I suggest getting only the solder and going for a cheaper iron.

Okay, so what you're saying is you do not necessarily need additional flux if you're using rosin core? Makes sense. Getting a pen sounds like a good idea here then, and will probably be much cheaper. Thanks!

I am thinking of buying these two rolls of solder:

Kester 44: 63/37 .031 diameter (For general soldering)

Kester 44: 63/37 .020 diameter (For SMD's)

& Kester 951 in a 12mL pen

Would these be suitable?

The solder I linked is 0.8mm. A lot of those Amazon descriptions are wonky, but just check the manufacturers part number. I think Dave suggested 63/37 with <0.5mm, so you can try to find that if you like.

http://www.kester.com/products/product/44-flux-cored-wire

They make more types than you can shake a stick at. A lot of them aren't even stocked anywhere.

Edit: Found one: https://www.amazon.com/Kester-Rosin-Core-Solder-Spool/dp/B00068IJWC

Maybe in USA/GB.
For me, it’s $60


Edit: now $90
amazon.fr

BUT I ordered it even if it was 3x more expensive and I don’t regret that choice

This, this and this should get you started.