EEVblog #562 - More SMD Oven Reflow

[EEVblog]

Dave assembles his first uCurrent in the SMD reflow oven.
With random running commentary while pick and place assembling.

[jesuscf]

Securing the strips of parts tape to a piece of soft wood board with push pins is much easier than using tape.  The push pins fit perfectly into the tape's holes.

[dumle29]

Dave, you might want to take a look at this

[nitro2k01]

Or as told by Mike:

[EEVblog]

Dave, you might want to take a look at this

I know. I don't have a vacuum pump. Will eventually get one.

[scopeman]

Nice Job Dave.

Now you have me thinking about another project - a DIY SMD reflow oven. As if I need yet another project!

Sam
W3OHM

[MatCat]

Nice Job Dave.

Now you have me thinking about another project - a DIY SMD reflow oven. As if I need yet another project!

Sam
W3OHM

I just got done doing one, works fantastically, I am documenting it here https://www.eevblog.com/forum/projects/another-diy-reflow-controller/

[Nermash]

Will there be any review of that Metrahit Ultra?

[Michael_P]

Oh!
Dave, could you please recommend or suggest any cheap source of current reference, it would be perfect.

[SeanB]

http://www.voltagestandard.com/DMMCheck_Plus.html

Simple low cost one, though might not be to the spec you want.

[redben]

How would you use this oven with smd parts on both sides ?
Does the soldering paste hold the components upside down ?

[SeanB]

You would need an extra stencil to screen on an adhesive to hold the components, allow it to dry then screen on the paste, then place the underside and activate the adhesive to hold the components. Then paste the topside and place and reflow to do all at once. You can see this on some boards where the components are held down by red dots of thermoset adhesive then reflowed.

[trackman44]

Now that, my friends, is uCurrent Gold #1!! Would probably be worth alot.

Will

[Towger]

What's the ticking sound during the oven shots?  It seems to be there when the oven is not on, so not the controller turning it on/off.

[EEVblog]

Dave, could you please recommend or suggest any cheap source of current reference, it would be perfect.

For the class required to test the uCurrent, no such thing as really cheap. I'm building a not-so-cheap one now, but still <$100 maybe.

[robrenz]

What's the ticking sound during the oven shots?  It seems to be there when the oven is not on, so not the controller turning it on/off.

Probably the oven mechanical timer. It would have to be turned on for the oven to work since the oven mains plug goes into the controller output.

[mikeselectricstuff]

You would need an extra stencil to screen on an adhesive to hold the components, allow it to dry then screen on the paste, then place the underside and activate the adhesive to hold the components. Then paste the topside and place and reflow to do all at once. You can see this on some boards where the components are held down by red dots of thermoset adhesive then reflowed.

Unless you have big/heavy parts on both sides, you don't need glue - surface tension will hold parts on during the second reflow.
Probably the biggest difference is your stencilling setup needs to be able to support a board with parts on the underside when stencilling the second side, and of course you need to support the board during reflow. 
 

[trackman44]

What's the ticking sound during the oven shots?  It seems to be there when the oven is not on, so not the controller turning it on/off.

Probably the oven mechanical timer. It would have to be turned on for the oven to work since the oven mains plug goes into the controller output.

You could hack the oven and remove the timer, if its only purpose is for reflow work, but I wouldn't toast anything edible, that's for sure

Will

[mikeselectricstuff]

What's the ticking sound during the oven shots?  It seems to be there when the oven is not on, so not the controller turning it on/off.

Probably the oven mechanical timer. It would have to be turned on for the oven to work since the oven mains plug goes into the controller output.

You could hack the oven and remove the timer, if its only purpose is for reflow work, but I wouldn't toast anything edible, that's for sure

Will

I left the electronic timer on my oven, and use it as a fall-back set to 6 mins to prevent incineration if I forget to check it..

[hikariuk]

What's the ticking sound during the oven shots?  It seems to be there when the oven is not on, so not the controller turning it on/off.

My guess would be the sound metal things make when they cool down and contract.

[ion]

Dave, you might want to take a look at this

I know. I don't have a vacuum pump. Will eventually get one.

You could get an aquarium air pump and reverse the valves - I made a decent pickup tool like that.

[MatCat]

I just scored a VIRTUAL INDUSTRIES V8000 SMD-VAC-GP Vac pen on ebay for $60!  Got it in today and I must say it's pretty nice, beats the pants off of placing SMD with tweezers .  The model I have is an older model but the company still makes them and they start at around $300!  So I think I got a good score, plus ebay has variants of it.  I plan on doing a photo tare down to check it out, will have a thread for that soon .

[Stonent]

Dave, could you please recommend or suggest any cheap source of current reference, it would be perfect.

For the class required to test the uCurrent, no such thing as really cheap. I'm building a not-so-cheap one now, but still <$100 maybe.

Considering some of those resistors were in the dollar range, I could imagine costs going up significantly with precision.

[Stonent]

If anyone's looking to roll your own reflow oven, Kevin Darrah had a couple of nice videos on it.

He, like Mike, left the time enabled and also left the internal thermal protection enabled in case the microcontroller goes into a runaway mode. That way the oven will turn off by itself and at least won't go over the maximum safe temperature for the oven.  Also he found that he could get a lot better temp control by coating the glass with foil.  He also mounted a small fan in the back to circulate the air to help eliminate hot/cold spots but my concern with that would be even with the fan on a standoff, it could start to melt.

One thought I had is you could also do it without modifying the oven at all. Just move the electronics into an outlet strip or use a Power Switch Tail that is controlled by your Arduino. 

The actual setup he had was, Arduino (well AVR board programmed as an Aduino), cheap Walmart oven, Sharp 16A/250VAC solid state relay with heatsink, a start button, K type thermocouple, Maxim thermocouple amplifier,  and a standard Hitachi interface 2 line LCD.

Video 1 is the teardown and conceptualizing of the design, Video 2 is his finished design and explanation of what he came up with.

[trackman44]

Wouldn't it be nice if you could cut some louvers on the top that were attached to a servo controlled by the Arduino? Then you'll have a proper cool-down cycle. That would be awesome.

Will