Somehow missed this thread starting, guess it's better late than never....
My story goes something like this:
Back in 2006, I decided to start selling some products I had designed. For ease of assembly (so I thought), I designed these products with through hole technology. Initially, I was hand soldering each board. Then someone told me about dip soldering, so I was dipping boards in a pot of molten lead or more accurately a electric skillet modified so it would get hot enough to melt solder in it. That was very nasty. A year or so later, I bought a wave solder machine.
Fast forward to 2010 and I had a really good year, well at least on paper. Because of the details of the US tax code, I had about $80K or so of profit according to the books and very little cash to show for it - since most of the $80K went into inventory which you can't call an expense until you actually sell it. I had also been looking at/for a pick and place machine for some time - mainly because through hole was becoming so obsolete it was hard to find certain types of components in through hole. Because of another part of the US tax code, one way to resolve these issues is to go out and buy a big piece of equipment, write it off in a single year, and then pay the loan off over time, spreading the tax impact over several years. So, I went out to a vendor which I had been looking at for some time and bought a surface mount line consisting of a Manncorp/Autotronk MC384 P&P machine, a small batch oven, and a dry box.
This was one of the best purchases I've made for the business. I typically use the same parts over and over in my designs - I have around 30 different boards we assemble, and all of them use the same power supply section, I use the same capacitors, etc. Because of this, once a part goes on the machine it stays one the machine. There are some very very low volume parts that we do hand place, but almost everything else is just one the machine. (we probably hand-place around 100 parts/month, if even that many).
I did spend some extra money on a high-precision dot dispenser for solder paste on the machine. This allows us to do a certain amount of assembly without a stencil. For instance, all of the prototype boards which come in are done on the board, and I don't bother with a stencil. There are a few very low volume products (like we build maybe 20-30 a year) that we also use the dispenser for. I wouldn't recommend this for high volume runs (we have a stencil printer for those), but for prototypes it's great.
I will say that the machine has relatively trouble free. I suspect a lot of this is because it was a brand new machine. Not to say it isn't without it's problems. I think the biggest two I'm aware of are issues where the cover tape on a reel will remain stuck to the carrier tape and the feeder misfeeds when it reaches the pick location. And the other are odd vision issues which prevent proper placement - usually caused by some component change or difference such that the vision doesn't do a good job of figuring out the actual alignment of the part on the head.
Every once in a while I'll send out one of our higher-volume products for an assembly quote just to check to see how we're doing cost-wise. Although it's getting closer to what it costs us to do assembly every time I do this, so far it really hasn't come close enough to seriously consider it. Plus, I have to consider the somewhat intangibles such as control over the process, and also that ability to do one-off prototypes using the actual machine and parts we'd be using in production.
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