For me, as I have moved to smaller and smaller parts, the days of iron/wire are largely gone. Even though it's possible, I don't bother anymore since there are so many great options out there from super DIY/cheap to over-the-top sophisticated.
My daily work includes prototyping and and small batch production with SMD passives down to 0402, but more typically 0603 and 0804. .4mm QFN's present the biggest challenge for me, but I have managed to become friends with those packages after some patient hours of trying.
SUPER CHEAP:
Manual syringe with TYPE 5 solder. It's more expensive, but the very fine solder powder allows me to use fine needles which is critical. Putting paste down with toothpicks is a waste of time unless the components are huge. If you have a few components, this works. The downside is that its hard to be consistent and your hand will get tired pushing paste through a tiny 22ga needle.
PROTO STENCILS:
These things can be pretty handy and don't cost much. I have always been dissapointed with Kapton for small pitch devices. The PROTO STENCILS from houses like STENCILS UNLIMITED and SUNSTONE are steel and have the edges bent into a box. They include a whole placement and squeegee kit. I have used these with pseudo success with .5mm but it takes a delicate touch and some practice. Generally not very consistent since they are not stretched and just taped down. Saved my butt on a few projects before I had a real printer.
COUPLE 'O BUCKS:
I also have a Zephytronics Air Mill solder paste dispenser which is quite awesome. The machine allows consistent deposits without any effort. This setup allows a lot better precision because your muscles are focused on placement while the machine does the hard work of pushing the paste out. Even though it has a timer, I just put it on manual an control the output by "feel". The learning curve was a few hundred components and then I was plowing through proto projects faster than I could order-receive-setup a stencil. I have been successful at using this method to place fine pitch but it is not a free lunch. The pad design is critical for leadless devices and I generally have to do some hand work after re-flow.
COUPLE MORE BUCKS:
Cheap printers for framed stencils are a big step up - but cheap means cheap. I looked at most of them and they are all marginal pieces of machinery, but still a quantum leap forward compared to the previous options. I got the MANNCORP RT2100. They are not kidding when they say "Entry Level Printer". I am a machinist [and MECH ENGINEER] with a 5-axis CNC shop so I was able to make modifications and PCB holders that were good enough for .4mm pitch. It is no longer a chore to deal with fine pitch, I have done hundreds of PCBs with this setup followed by 100% manual placement of components and NONE failed. If I did not have the resources to modify the machine myself, I would have been looking at the $3k models. The problem with the low-end it that they are hard to get a good alignment and tend to be be jiggly. The problem with the higher-end, is that they get expensive real fast. Starting with a low-end machine and modifying it was a fast way for me to get great results. Not everyone is looking for a CNC project though. Without the mods, I would have thrown the RT2100 off a bridgee.
I had been looking at various P&P machines but decided that going in the order of OVEN first, PRINTER, second, and P&P third is a good path. The addition of the stencil printer has been awesome.
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