> Hand-soldering PTH is painful...  We started out that way.   Then I went 
> to the "dip the whole board in flux, preheat it on a old electric grill, 
> and then dip it in a pot of molten solder" method.   That makes PTH much 
> easier, except doing 100 boards/month that way also becomes so tedious 
> after a few months that it's really hard to feel the desire to run a 
> batch of boards.   This is primariliy because of how agressive the 
> environment is - you know, flux fumes, hot solder, etc..  It is not 
> pleasant at all.
> 
> The Wave Solder machine made this a whole heck of a lot easier.
> 
> What I like about the PTH process the way we do it today is that my 
> hand-inserter is able to do the insertion at their leisure onto some 
> foam-sided 1/4" boards.  Or more specifically, we have cut/trim machines 
> which precut all of the components to the appropriate length.  Then at 
> insertion time, we just lay the panels on a piece of insertion-grade 
> conductive foam which we have glued to a piece of paneling as a backer, 
> and the person doing the insertion is able to insert how ever many 
> boards we expect to solder with no rush to get them actually in the wave 
> solder machine.   Once every couple weeks we fire up the wave solder 
> machine, and run a fair number of boards through it, and basically stack 
> them for use over the next couple of weeks.  Those boards could have 
> been inserted days or weeks previously.
> 
> In the SMD world, I dislike the "criticality" about the whole placement 
> process.   That is, from the point you put the paste on the board, you 
> only have a certain period of time to place all the components and get 
> it into the oven.   Or put differently, if you hand-place your placer 
> can't work on a different schedule than the person who is the oven 
> person - who unfortunately is often not the same person just because 
> good eyesight and fine motor control skills are not necessarily in the 
> same person as someone who can tweak an oven and figure out what they 
> need to change in the process to get good results. 
> 
> I am curious though...  How are you "pasting and placing" the SMD 
> today?    I do have some low-volume products I am really thinking about 
> doing this way just because SMD is the easiest way to do them.
> The cost of a paste dispenser really depends on the unit.   Some are 
> really cheap - a couple hundred dollars.  Others more so..   Really most 
> dispensers are just that syringe you already use mounted to the head in 
> such a way that the P&P can put the syringe in the right spot and 
> dispense.  I'm assuming you're using a semi-automatic dispenser on the 
> syringe....  if not, then modify the above statement accordingly.
> 
> What I really don't like about the whole stencil thing is the setup and 
> cleanup costs.   Compare the two options, in my context.  That is, I 
> usually run a 4-5 different panels, perhaps 3-4 "copies" of each panel.
> 
> Stencils: You have a set of stencils for each panel.  For each panel you 
> have to mount the stencil including board alignment, "screen" 3-4 
> boards, clean up that stencil, put the next one on, and so on.   You're 
> putting down 4-5 stencils and cleaning 4-5 stencils and it's a real 
> pain.  Plus you're placing, which is included in the other option.
> 
> P&P w/dispenser:  You have a P&P machine with a dispenser.  The P&P 
> machine has all of your common parts on it already.  The dispenser needs 
> to be set up once at the start of the entire run (and perhaps be 
> refilled occasionally), but to run 4-5 different panels, it's just put 
> the board in the P&P, select the right board file and hit go.
> 
> I would expect that one person could keep the P&P loaded, and run the 
> boards through the oven while the P&P is placing the next board, with 
> little mid-run downtime.
>> Have you considered used equipment? I think that a used machine in good 
>> working order would be more affordable.
>>   
> I have a used Zevatech/Juki P&P I got off of ebay.   I've been playing 
> with getting it working right.  It would be good to place larger parts, 
> but not smaller ones.   The problem I see is that the used equipment 
> seems to be not much less than the new one, and the new ones come with 
> some setup help.
> 
> Plus there is the whole feeder thing.   I'm still looking for the right 
> used P&P, but I sure haven't found it.
>> When I made the original post, I was hoping people would suggest auction 
>> sites or used equipment dealers, along with recommendations for what could 
>> be considered "starter" pick-and-place machines. :)
> I would suggest of course ebay, and perhaps smtnet or caeonline or one 
> of the similar used brokers.   The wave solder machine I got through one 
> of the brokers and I've been pretty happy with it.  But a P&P machine is 
> a whole lot more complicated.
> 
> -forrest

This is an excellent summary. We went through almost the same process 
except we never got a wave soldering machine since I believe TH is dead. 
We ended up being a contract manufacturer doing mainly small runs 
(100-5000).

You can easily do all SMD operations in-house except automated pick&place.

For very small runs we found a pneumatic foot-activated paste dispenser 
very useful. It can even do fine pitch, of course there are bridges but 
that's easy to fix with high viscosity tacky flux and hot-air (we are 
very happy with www.amtechsolder.com consumables). We place by hand 
using a vacuum pick tool. You will need a microscope, strong light, 
steady hands and good eyes. We use at least two employees to do it 
quickly to avoid paste drying out. The oven is not critical at all 
(unless you want lead-free), you only need temperature reading and a 
powerful heater to bring up the temperature quickly enough.

For a bit larger runs (20-100) or lots of components you really need a 
stencil. Mylar is finicky and only good for 1mm+ pitch. You can print 
without a printer but it's slow. If you misprint, you must wash the 
boards thoroughly with solvent (ultrasound bath works perfectly) since 
the balls will stick to the board. A manual printer is great, but you 
are right, changing and cleaning stencils is a real pain, there is no 
way around it.

The automated pick&place is really not for occasional use. We bough our 
JUKI/Zevatech from a guy just like you, they realized that it's just not 
worth the trouble. You will need an employee who will only work on the 
machine, who will know the quirks and problems. The setup requires a lot 
of time, each time you will have a few bad boards until you get it 
right. You also can't use cut tape with 100 components that you get at 
DigiKey since you have to remove 10-30 components to load the feeder 
(perhaps there are better feeders that fix this).

You also need a LOT of feeders. We have 150+ for ours and we still want 
more. This can be a real problem if you buy an used machine, also the 
nozzles and other spare parts. Detailed manuals are also a must, we 
struggled a few weeks until we managed to calibrate ours and we had all 
the manuals.

If you do all this, like we did, then, why don't you become a 
manufacturer for other people? My point is, even if you don't want to 
send your small runs to a manufacturer like us, you must have someone 
nearby who has the machines sitting there and who will do the assembly 
for a decent price.

If you buy, buy with top and bottom vision, get spare nozzles, and check 
if you can get extra feeders, avoid cheap machines.

Djula
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