New Pick and Place machine

The delivery of the new Pick and Place machine was confirmed by the shipping company for 17 Dec 2012.  Finally we will have an accurate, fast machine.

Pick and Place machines are car sized purchases and a lot of thought and research went into the choice of the machine.  After sifting through the options for desktop machine only two machines were seriously considered.  The Manncorp 7722FV and the DDM Novastar LE40V.  Both machines are small enough to fit through the doors to our work area.  This is a big deal, kind of a showstopper.  Pick and Place machines can be large and heavy and are made to be rigid.  This often means that the frame is welded or cast and can not be disassembled.  Also, disassembling a machine means re-assembly and alignment.  Alignment is also critical in the machine meeting its accuracy spec.

The runner up was the 7722FV.  Several smaller manufacturers such as Adafruit and Eurobuilder went with the 7722FV and since they must have done their homework I had a very serious look at the machine.  It is a bench-top machine and does not have a welded or cast frame.  It is reasonably light, around 150 lbs.  It has real feeders and optical alignment.  It is reasonably fast at around 2200 components per hour and can handle all the components that I see in immediate future.  Here are some photos http://www.adafruit.com/blog/2009/10/13/our-manncorp-7722fv-pick-and-place-is-here/

In my evaluation of the machine I was slightly uncomfortable with the stated accuracy of the machine and to a lesser extent the way in which the machine is constructed.  The machine’s accuracy is adequate for current parts but it has no room for the feature shrink in packages occurring now.  A while ago, everything was dip packaged and pin pitch was 2.5mm.  Then everything was leaded surface mount.  Now lots of new parts are only available in leadless surface mount and ball grid (or chip scale) packages.  Currently the ball pitch is already down to 0.4mm and t is likely to shrink in the future.  0.4mm is the limit of the 7722.  Also, the 7722 is an open loop machine.  Positioning takes place by counting pulses after a reference was established, the gantry position is not measured.  The reference is found by bringing the part over an up-looking camera and doing a pattern match to a known good position of a part on the nozzle.  The nozzle (and gantry) is then moved to the desired position and the part is placed on the PCB and held in place by the solder paste.  In any well designed machine the movement does not miss steps after the alignment and if the part does not move on the nozzle the only error is the positional error inside the step.  This may appear to be negligible but in practice it depends on exactly where the motor is commanded to stop and the speed at which the motor slows down.  Friction, bending and stretching and temperature effects all add to the complexities.  That is why the accuracy is not equal to the resolution.  The stated resolution of the machine is much better than the accuracy.

My second reservation about the machine is the construction using Aluminium profiles.  When stiffness matters this is not the best way to build the frame.  No doubt the machine meets its accuracy when it is new but I don’t know how it will age.  Secondary things that I took into consideration was the design of the feeders.  The feeder design is ‘classic’.  It has an indexing mechanism and can advance the tape quite precisely and quickly.  The feeder is a mechanical design.  I can’t remember if the machine had an option for ‘smart’ feeders but the default feeder for the LE40 is smart.  A ‘smart’ feeder has an electrical interface to the machine and it can be identified by the machine to verify that it is in place.  Smart feeders also maintain a count of the parts used making inventory tracking easier.

The LE40V was the winner.  The machine base is welded steel and the motion is closed loop in the sense that the actual gantry position is measured using linear encoders.  This gives me confidence that the long term accuracy will be the same as the ‘factory’ accuracy.  The other major factor influencing my choice was that DDM Novastar gave me access to the manuals before purchase and the manuals are complete, legible and in good English.  They even contain circuit diagrams of the machine.  From the manuals I recognized the motion controller used in the machine as a controller made by Galil.  I have first hand experience using their controllers in motion systems and they are used wherever high quality motion control is required.  My current machine uses trapezoidal profiles for the motion and the jerk is not welcome.  S-curve motion is definitely not a luxury.

The price of feeders are also a consideration.  Very often you spend as much in feeders as on the machine.  The LE40 has a very clever bank feeder for 8mm tapes.  8mm tapes are by far the most common size and you can never have enough of them.  The bank feeder is a ‘single’ feeder for 12 8mm tapes and it costs less than a 5 individual 8mm feeders.  Since I have existing products I knew from the beginning that I need more than 12 8mm feeders and this is an economical solution.  The prices for the LE40 feeders are comparable to the feeders for the 7722 but they are smart feeders.  Even though the initial price for the LE40 was higher than the 7722 by the time I factored in the price for the feeders, and external PC and a compressor, the LE40 ended up at roughly the same price.

As they say in the movies, watch this space.  I will provide pictures and details of my experience with the machine.

Happy hacking.

  • honestann

    Thanks for the very helpful comparison. I have been planning to buy a pick-and-place machine for a couple years, chose the LE40V at that time, and now that I’m finally about ready to buy… assuming I can afford it… the LE40V still looks like the winner as far as I can tell. My PCBs have lots of 0201 components, 0.25mm pitch QFN type packages, and 0.40mm pitch BGAs, so I need something up to that accuracy or better, especially looking forward.

    Can you tell me what price they quoted you for the machine and the feeders (separately if possible)? If you don’t want to post that here, I assume you can read the email address I entered, and I’d love to hear from you about prices and other details, especially if you already received your machine!

    Oh, another question. Let’s say I can’t quite afford the machine with all the feeders I should have. Do you know whether it is possible to tell the machine to mount a subset of the components (with the feeders we do buy), then stop while I load new components into the feeders, then continue and mount those components, and so forth (hopefully no more than 3 or 4 iterations)?

    • Hi,
      The LE40 is in almost daily use and I’m satisfied with the machine. The accuracy is good and the repeatability is exceptional.

      In principle you can build a board with one feeder by changing the reel loaded on the feeder after mounting that value component. Loading and unloading reels is tedious and time consuming and wasteful of components, specially small components.

      When you work with small components such as 0402, don’t underestimate how good your solder paste application needs to be. I don’t use passive components smaller than 0603 if I can avoid it. This is to keep the yield high. If you are new to surface mount manufacturing then you should avoid 0201 components like the plague until you have your recipes sorted out. That includes solder paste application, pick and place machine setup including vision, reflow oven profile and rework procedures. While you are building boards rework is a fact of life and unless you can fix what doesn’t work, you won’t have anything to sell.

      Another thing that matters is PCB flatness. The smaller the components, the more critical board flatness is because the machines can’t correct for it. If you don’t get enough pressure of the component into the solder paste then it can tombstone or simply fall off.

      Hopefully this helps
      Daniel

  • Hi Shane,

    I don’t own a 7722 so I’m not the best person to answer this. My understanding is that is supposed to be able to place 0201 but it needs a special nozzle and feeder to handle the small parts. You should ask Manncorp to get a definitive answer.

    Daniel