Upon finally finishing reading the entire micRo thread today my thought immediately turned to two things. 1) How can I make one of these as a CNC router to replace my current Roland MDX-20 (http://www.rolanddg.com/product/3d/3d/mdx-20_15/mdx-20_15.html) and get some more serious fab ability, as well as 2) Brainchild really made me start thinking about how awesome it would be to have an automated pick & place machine with his comment half way through the thread. As someone who currently does hand PCB assembly (boo!!), it would be an amazing saver of time to automate the pick and place functionality for many of the small components that I have to tediously step through. On large boards it can be a real drag to count through all the parts needing to be manually placed and soldered. I can see how the precise X-Y-Z can be achieved with the micRo, but how would you automate the vacuum control and feed mechanism for the component pickup assembly? Inexpensive vacuum tips and motors could be sourced from Madell Technology (http://www.ntscope.com/m2-6.html) but would have to be coupled with a miniature air valve (http://www.numatics.com/applications/products/valves/s.aspx) and air filter. Homing would be key, and could be achieved with limit switches, optical interrupters, or mechanical end stop detection. Capacitive sensing would be ideal for height adjustment (http://www.lionprecision.com/capacitive-sensors/cap-products.html) I am sure that more reasonable suppliers could be located for all the above parts, and the difficult aspect of all of this would be tying all the additional sensors into the control system. End calibration and touch based height sensing would be a boon for other CNC mill operators to aid in auto calibration, so maybe we can get some other CNC'ers interested in this project. Any ideas on how to move forward out there?

Well you know I'm all for it.

Nothing to it really, a capillary "picker" powered by a vacuum pump. The pump is switched on by a relay to pick up the piece, and switched off upon deposit. If you want to use the pump as a vacuum table, you can use a simple solenoid valve off the same pump for switching the picker. Control of the solenoid is easily programmed with EMC2's HAL (hardware abstraction layer), and there's even ports left for smd roll feeders etc. The rest is just CAM'n up the positions of the pieces, and the locations of the smts, paste etc.

Something I am interested in is using an IR lamp for the reflow. I'm not sure if IR can flow the solder or not... Ever heard of it?

We used to use a vacuum tip to move thousands of tiny reaction vessels around...I would consider using a dual head pump / compressor and switching between vacuum and regulated pressure to push the piece off the head. Otherwise you can end up with stuck parts and a mess of tiny electronic bits.

Let me see...

As I understand it, the SM piece is picked by vacuum, dunked in flux/paste, then crammed down onto its position where the paste takes hold and the capillary, free of vacuum, moves onward.

Oh yea, reaction vessels?

Ummm yeah, I forgot about the solder paste, so that probably wouldn't be too much of an issue. The line probably at least needs to be vented to air then, even if the pump is left running.

As a side note, the paste is usually applied through a stencil first, then the pieces are just placed on top. Of course, the micRo could easily cut the stencil first...



Yeah, the blood analyzers performed all of their analysis in reaction vessels aka cuvettes:

http://www.stago-us.com/pages/products.php?section=vds

4 independent 3-axis arms moving blood samples, reagents, and cuvettes for ~350 tests/hour:

http://www.stago-us.com/pages/products.php...n=view&id=1

Fun stuff.

All of the reflow ovens that I have used are either convection or IR+convection. I have not seen any IR only ovens, probably because the heat would be incredibly localized. That and the power draw is very high, think in the kW range. It might be possible to have to IR on a smaller scale to reflow the components by applying local heat. Decent ovens are cheap enough on eBay though, probably not worth your time to try and solve that problem.

Stago uses NT??!!! BAD ROBOT!


BTW, where'd you get the blood??

About this venting...on the vacuum line is a simple ball check valve that maintains the negative line pressure as long as the vacuum from the pump is present, the instant the pump stops, the ball falls and the line is vented to atmosphere. This little doodad limits the need for more expensive pneumatic valves, requiring just a relay and the ball-check.

Hmmm, yes I knew about the paste stencils, but lately have seen the "waggle bots" that dunk and plop. This is akin to micRo speed, so has kept my interest as "the method". The 'dunk' portion doesn't add that much time really...





I appreciate that! Robin pointed out the 'no-duh' thing, which is chips are black IR sponges. The reason I am interested in a "portable" heat source is that I envisage a machine that solders as it goes. I've posited numerous ideas, but my favorite is that the "picker" capillary is reversely used as a highly localized hot air gun after deposition. How does it improve upon anything? I doubt it does...I think I like the 'art' of it; that is a machine that is more autonomous...for instance, it can etch, place and reflow in just one continuous operation. That makes it closer to a "board printer" in my mind, so I enjoy thinking on it (hey, it's the only thrills I get these days).

Yeah, NT....can't really defend that. I haven't worked or consulted for them in many years at this point, so that's my defense.

These are installed 95% in hospitals and the rest in research labs. If you ever get blood drawn with a blue top tube, it might go into one of these analyzers to determine how well your blood clots (and if it's not, which protein factor of the chain reaction is out of whack). So, it's your blood!

Yes, the simple ball check valve - simplicity is best when it works.

Cheap reflow= electric skillet.. There's a interesting little tidbit concerning reflow ovens vs. the electric skillet over at sparkfun. If I remember correctly, they ended up liking the $15 electric skillet more in the end. I could see a means of cheap and reliable automated control for the reflow-skillet being provided via EMC. As far as doing all of this in one un-broken operation.... Applying a stencil could be done in-situ , if only part of the work area would be used.. That way you could keep the registration. Though I could see possibly "dunking" the components in solder paste.... But that sounds hard to make consistent.