How to NOT reflow your boards. 1

[itsmoked]

This morning about 4AM I was working on a 10 board build that my client would like ASAP. I ran my reflow oven
on the first four boards and essentially stood there for the entire twenty five minute cycle with a flashlight
watching the proceedings. It all went fine...

Getting into the rhythm I carefully loaded the second four boards and hit go.

I closed the door to the "shop" part of my office where the stinky (flux) smell normally evolves and continued
puttering about. I have a large squirrel cage blower blowing out of my bathroom window and open the "shop"
window to keep the noxious fumes out of my office.

The controller ramps the oven up to drying temperature and holds that for a few minutes, about a 15 minute process.
Then it ramps fairly quickly to reflow temperature where all the solder melting happens. It stays at reflow
temperature for something around one minute then switches to cooling. Where I come to its aid by cracking the
oven door for about 5 minutes then open the door fully for about 5 minutes. Remove the boards step-and-repeat
as required.

Well this morning second run of four, I open the door to the shop, the oven is eye level immediately to the left
about a foot back from the plane of the door frame and I'm greeted by the sight of ORANGE smoke roiling out the
oven door and ORANGE slime oooooozing down the face of the oven. Through the oven door window I can see 2 inch
high, inch in diameter, black columns of black foaming putricity! I can't see across the room but I can see the
reflow controller displaying 226C and telling me it was in the reflow hold period - I was a few seconds early..

I yanked the very hot oven door open belching more heinous stench out into the space but hoping like heck I'd
headed off ignition of the board fiberglass and resin. I also hit the disconnect switch that isolates the oven
from the controller's power output.

I ran outside, took a deep breath and fetched my full face respirator out of my shop cabinet and ran outside
again gasping for air. After dawning my respirator I opened my office door and all the windows and had to stand
around waiting for the place to air out. This gave me time to think about the loss of four boards out of a build
of 50. Besides the immediate loss of half a K of product I would now have to go thru a complete buying cycle to
replace the parts. A low quantity cycle at that!! And, the 5 hours of stuffing too. Groan. Plus I have to
figure out what's wrong with the controller.

I totally reeked after this. That is the worst &*@%#$ stinking smoke! I had to leave all my clothes on the driveway
when I got home, lucky it was 5AM and only Jupiter and Mars were witness.

Here's the resulting master pieces:

Keith Cress
kcress -

http://www.flaminsystems.com

 

[VEBill]

Crikey.

 

[ScottyUK]

It will clean up.

 

[itsmoked]

I don't know if I ever will.. A shower and laundering everything I was wearing has merely
blunted the smell. I'd rather be sprayed by a skunk.

I tore the reflow controller apart looking for dried out electrolytics only to find it was
completely SMD with none apparent. One down-side was they powered it with an imprisoned
wall-wart which is, of course, inscrutable.

I hate untrustworthy electronics! I'll just have to baby sit the entire profiles over and over
and over and over.. ad nauseam.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[MacGyverS2000]

I'm assuming this was a DIY style of reflow oven? NEVER leave something like that alone. I only trust pre-manufactured and CE-cleared/UL-approved items when it comes to that much power... ovens, crockpots, etc.

Us laser guys know that mantra cold (at least the ones who have never had a catastrophic fire, that is). The ones who didn't follow eventually lost something serious, ranging from the machine itself to their entire building. I feel for you... nothing like seeing the flame rising and trying to figure out what to do first, kill power or put out the rising flame.


Dan - Owner

http://www.Hi-TecDesigns.com

 

[mcgyvr]

flaminsystems is right on for you...

 

[analogkid2digitalman]

Bummer Keith, I guess the bright side of the story is that it could have been a lot worse.

You may want to think about adding some type of smoke detector and over temp safety relay to kill the mains.

-AK2DM

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"It's the questions that drive us"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 

[itsmoked]

I think I'm going to hunt down a ramp-and-soak commercial temp controller and a separate over-temp monitor, both with a loud alarm I can hear through a shut stink-door over music.

Yes analog, I suspect it was moments from busting into flames. I figured out it had just crashed - no watchdog and sat there dumbly with the power relay closed.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[mudandsnow]

A little isoprop should sort those boards out.

 

[itsmoked]

My shop still reeks. My clothes still reek. I got a ramp and soak controller today that I'll be installing momentarily. It'll have over-temp alarms that will drop out a relay to prevent any recurrences.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[flexoprinting]

Good morning Keith

Surprisingly many people are not aware of the dangers of plastics fumes, I was a volunteer Firefighter and part of my training
was information on this topic. There are many poisons developed while plastic or rubber burns, I'm not sure your respirator is
enough protection.

Be careful out there I enjoy reading your post and would like to keep it that way.

Chuck

 

[Skogsgurra]

I missed this. And now I understand why you suddenly need a controller, as told elsewhere. I also understand why you answer posts at untimely hours. I feel really sorry. This shouldn't happen to nice guys.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[DanEE]

Surprisingly many people are not aware of the dangers of plastics fumes,

Amen! I learned years ago in a product fire investigation that the compounds added to many plastics to pass the UL-94 flame retardant rating in fact contributes to the chlorine and bromine compounds given off when burned. Flame retardant rated plastics will escalate in their burn rate especially when the heat is concentrated in a confined area. It melts into a black goo like the petroleum it came from and burns as you would expect crude petroleum to burn.

 

[Compositepro]

The above is true but not for all plastics. Polyethylene and polypropylene are basically high molecular weight paraffin and smell like candle wax when burning. Acetal (Delrin) burns with an almost odorless invisible blue flame. It decomposes to formaldehyde which then burns. Oddly, it is often the flame retardants that create the noxious smoke.

 

[MacGyverS2000]

Am I losing my mind? I posted up some great suggestions of controllers, but the post is gone!

I'll try a shortened version...

ControLeo2 is a great option at $69 shipped... even controls a servo to open the oven door during those cooldown phases:

http://whizoo.com/reflowoven

Zallus had a Kickstarter... a bit more expensive (starting at $95), but adds a cool color LCD to the mix:

http://www.zallus.com/product/zallus-oven-kit/

Dan - Owner

http://www.Hi-TecDesigns.com

 

[MacGyverS2000]

LOL, looks like I posted the info in another thread

Dan - Owner

http://www.Hi-TecDesigns.com

 

[itsmoked]

LOL!! I was just coming to the same conclusion and bingo.

Yes Flexo I didn't breath much. I'm sure the people that saw me burst out the front door with the motion lights snapping on and me donning a full face respirator were thinking along the lines of Breaking Bad. While I know the all-purpose canisters on it can't catalyze everything, having all traces of the smell cut off is a positive indicator. It only took me perhaps 15 seconds to open windows and fire-up my big squirrel cage exhaust blower - that likely confirmed to all the spectators the BB angle with the alien smell.

Thanks for the sympathies Gunnar.

Dan and Comp; Can you imagine what pours out of a 40 foot boat burning to the water line? Gah.

Dan; I'm in a bit of a hurry here being in the middle of a production run so the fact that the Zallus appears to be on indefinite hiatus doesn't look good and the ControLeo2 is yet another gamble because the fools that designed it made NO adjustability into it. You have to "write code" to change anything. All you can tell it is the single spike temperature!! It takes care of everything else... SuuUUUrrre it does.

Keith Cress
kcress -

http://www.flaminsystems.com