A few things regarding all this...

I have modified mountsmd.ulp for generation of pick&place data (i.e. 
centroid or "XYRS") so that it outputs mils with comma delimiting, which 
a CM requested a few years ago when I was doing some initial designs. 
If anyone wants it, just ask.  (to jesse AT celestialaudio DOT com).

As mentioned the solder paste openings need to be segmented for some 
devices, this is particularly true of larger QFN, else they may "float" 
on too much solder and their "pin" pads not touch the board.  TI 
datasheets talk about this, as I recall, or google for info.  I made 
modified parts in Eagle to achieve this, and so far, no problems.  It 
can also be a problem if you need vias in the QFN pad.  If the via is in 
an area that gets solder paste, the paste can just flow down the hole 
during reflow.

I really want to get pick&place running ... for the same reason, I often 
need 25-100 of something, and while I have my usual shop relatively 
nearby (Meritronics) sometimes I just want to do it FAST, there is no 
practical (i.e. sane cost) way to get less than a 2-week turn, and it is 
usually 3 weeks.
A year and a half ago I bought one of these:
http://www.bidservice.com/browses/DHTML_PHOTOS.ASP?ProductID=13148&Mfg=MRSI&Mdl=501&InvNum=30063
off of ebay.  Needs total reprogramming for the modern era.  A big 
project, but if the specs are to be believed I should be able to do all 
the way down to 0201.

Anyone who is or will get serious about DIY P&P please let me know, I'd 
like to be part of a forum/discussion/development of basic motion 
control and image recognition software to do this.

Cheers...!
J



PICdude wrote:
> Quoting Vitaliy <piclist@maksimov.org>:
> 
>> PICdude wrote:
>>
>>> FWIW, I'm working on doing my own auto/semi-auto assembly, so more
>>> interested in the details of these processes currently.
>> Sounds cool. What is the motivation behind this project?
>>
> 
> Necessity.  We do 25-100 of many products at a time, and even for some  
> products that we do thousands of per year, it's better to run smaller  
> batches (250-500) so we don't have to float the cost of all those  
> components at once.  Our products are very similar components-wise  
> (layout, config, and firmware very) so setup time (reel changes etc)  
> would be minimal.  Conservative calcs show that in-house will not cost  
> much more.  Quality and appearance will be better too.  Add that I  
> haven't been able to find a local SMD solderer, so I'm doing most of  
> the SMD stuff lately, and getting backaches from being hunched over a  
> desk for hours on end.  CEM's have long lead times just to get a  
> quote, and I expect no more backaches from .  So it's pretty much a  
> no-brainer.
> 
> I got a decent conveyor oven already, but just need to find the right  
> PnP machine at a price I can afford.  In the meanwhile, I am seriously  
> considering building my own PnP.  Time is an issue, but I do have some  
> of the sharper kids from my robotics club ready and eager to help with  
> this though.
> 
> Cheers,
> -Neil.
> 
> 
> 
>> High volume assemblies are best outsourced to China. One-off protos are not
>> worth the setup time. However, it would be nice to have a way to build
>> 10-100 boards without paying an arm and a leg.
>>
>> Vitaliy
>>
> 
> 
> 
> 
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