Lets see if I can shed some light on this process. First off I'm an ex process Eng. that worked in a contract SMT manufacturing facility here in the US before every thing moved offshore. Actually started at Compaq the Motorola then did a stint with a little contract house then moved on to one of the big contractors. So what all this means is I know what I'm talking about.
1) The above poster is correct in that the first pic we have is a Screen printer. It's function is to apply solder paste to the PCB. The machine next to it in the same pic is a laser and vision solder inspection station. It's job is to make sure the screen print is good. It checks both the hight, registration and coverage of the past. Approximately 90% of all defects in a good SMT manufacturing process are cause at this point due to clogged solder stencils so in high volume shops you put a solder past inspection system in place to catch those errors while it is very easy to recover from them. You just wash the PCB and run it again plus clean the stencil before you have to many bad boards.
2) The next machine he takes a picture of is a Pick and Place machine which means he missed one. The actual next step after solder inspection is the chipshooter and as the name implies its job is to place the passive components on the board. When I left the business about 5 years ago the current state of the art was able to place about 10 components per second. This machine is basically a big gattling(sp) gun type of design. In that the placement heads rotate around a turret and the board moves (That is why you can only place small devices with it). After the chips are placed we normally also placed the smaller IC's with the chipshooter as well. You just have to slow it down to do that part or the IC's will slide off the board as it moves (it moves very fast normally about 12 inches per second and from dead stop to full velocity in under .01 sec's).
3) Now comes the pick and place machine that he did take a picture of. It's purpose is to place the larger components on the board. In this machine the placement head moves not the board. All components are both vision tested(leg bend left right test) and laser (for leg flatness or bend up down tested) before the component is placed on the board. Depending on the part and the number of heads on the machine the pick and place can place parts on the board at about the 4 per second range. Larger parts take longer mostly due to there size and or weight. Basically if you move the head to fast the part will fall off or become missaligned.
4) The next machine he takes a pic of he got right it what it does. It visually checks to make sure all of the parts are on the board. It will also check alignment and if the part has some distinctive feature it will make sure it is the right part as well.
5) The next picture is the reflow oven. It is basically a big convection oven the better ones are forced air ovens. The problem with his description is that he states that it heats the board up to 200c which is not correct it gets a little hotter than that. How hot you have to heat the board and components depends on the solder past and the components you are using. Now that most SMT manufacturing has moved to lead free paste it is mostlikly getting closer to 250c.
6) Visual inspection. Yes this is still done by humans. There are many issues with doing this by machine at this point that are not easy to solve. You can machine check components but we already did that before we put the board in the oven so why do that again. What the girls are looking at are the solder joints mostly. If the oven has lost a zone or the air flow is not right for some reason then the solder joints will change in color and how it looks. Again this is a very hard problem to solve with a machine because it is hard to see fillets and hills (the solder wick up the side of a component) with a camera no matter how high of a resolution you have because to see it you have to have light and the light will cause bright spots in the pic which will cause all kinds of issues. Again I is just simpler to pay some one to do it. Here in the states a good inspector made good money (we started them out around $15 an hour after they proved they were good they could get $20 an hour).
7) The pick he calls a functional test is not a functional test. It is a component test. It only tests the individual components in isolation.
8) The pic of the reals of components. The components are supplied in reals of paper or plastic for IC's. They are done this way so that the component can be presented to the chipshooter and pick and place machines at a consistent location. There are bulk type feeders (what feeds the component to the machine) but they have issues at this point in that they can not consistently present the component to the machine fast enough.
9) The pic he has labeled as the BIOS tape area. Typically programmed parts are supplied in plastic tubes. You feed the tubes into the automated programmer which will then place them back in another tube. The machine he has taken a pic of takes the tubed components and places them in Tape (normally Anti static plastic tape). This is so you can put the part on the Pick and place machine. Most pick and place machines do have tube feeders but because of the limited capacity of a tube (normally about 10-20 parts depending on there size) It is more efficient to tape and reel the parts in reels of a couple hundred at a time.
10) Skipping a bunch of worthless pics. On to the through hole assembly line. His fits pic of the through hole assembly line looks like final assembly so I'm going to skip it as it is out of order.
11) Through Hole hand assembly. Now quite a few post up some one wondered why this is still done by hand and was complaining about exploiting the worker and wonder why this was not automated. Well let me tell you. You really can not automate this process you have to do it by hand. And I'm talking from the experience of actually trying to automate this part of the process. The tolerances needed for modern through hole components make it such that a machine just can't do this. And the pin counts on modern parts also exaggerates the problem. All it takes is one pin misaligned and you have a defect. The cost to rework the part and the decrees in reliability almost makes you want to just throw it away. But because of part supply issues and such you rework the board anyways. Good through hole people get paid well and they are worth every penny.
12) I can't believe this person did not take a picture of the wave solder machine. After the through hole parts are put on the board the board is ran through a wave solder machine. It is called a wave solder machine because the wave of solder is created and the board is ran over the top of the wave. The solder hits the through hole pins and wicks up through the hole in the board and solders the part on the board.
Well thats it other then the final inspection, rework, ICT (in circuit Test) and then functional test then pack and ship.
Hope this long winded write up helps explain some of those pics.
