Prototype oven recommendations

I have thought these would handle some heavy loads:

for that money why not get something that is made for reflow?

-Lasse

[snipped -- line length]

No picture? The "suggestions" eBay offers look like they may be a bit small. (I'm not obsessed with money constraints; more interested in "not having to screw around" fighting the thing)

Hamilton's suggestion *may* have more "capacity" -- *if* stacking boards (i.e., on different "racks" in the oven) doesn't appreciably alter their individual environments (and the fan is slow enough to not dislodge components).

But, it still seems like a "toaster oven" solution...

Den torsdag den 4. september 2014 22.19.56 UTC+2 skrev Don Y:

I see pictures, search for T962

IR won't work in more than on layer

well IR reflow is basically the same as toaster oven

when you buy a reflow oven instead of a toaster oven you just get the controller that does the ramping of temperature and a fan to do the cooling

or go buy this:

;)

-Lasse

I'm not sure what popped up for you, but I got an eBay listing for a small desktop purpose-built reflow oven.

It's a no-name Chinese one, so it may end up being worse than a restaurant oven and a controller, but it is purpose-built.

--

Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com

high enough for some lead free solders. Then you need to take into account the accuracy of the setting so it might be even lower.

--

Rick

I found the listing. But, first time I went there, no picture though lots of pictures of "suggestions" below the listing ("People who viewed this item also viewed").

I revisited the page and the picture now appears. Perhaps I didn't wait long enough for it to load...

Yeah, but that's less than a square foot (or, is my math wonky? too early in the day... :< )

I was hoping for a "couple/few" square feet. To cook a couple of small batches of different designs at the same time.

Yes, but I understood his to be more of a "real" (conventional) convection oven. E.g., resistive heating element + fan.

Temperature range and better insulated, one hopes. Most of the toaster and countertop ovens I've seen have little more than their metal skin separating the internal heat from "ambient".

[line length]

Exactly. And hysteresis in the controls, etc. I'm not a hobbyist so pinching pennies isn't necessary. OTOH, I'm not looking to sacrifice my *garage* to PCB fab! :-/

Speaking of ovens... timer says the cheesecake is ready! Gotta adjust my priorities, accordingly! :>

I think the fan to do the cooling is important. Once you get to reflow temperature (especially Pb-free) you want to get the temperature down PDQ.

Best regards, Spehro Pefhany

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"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

Dunno about the ovens, but the supplier is great. Those bottom-of-the-barrel eBay reflow ovens get poor reviews.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

Den fredag den 5. september 2014 00.38.12 UTC+2 skrev Don Y:

roughly 7" by 9" but with a cycle time of maybe 5 minutes you don't gain much by doing it all at the same time

That just means you waste a bit of energy heating the room, with closed loo p temperature control it doesn't really matter

ling

-Lasse

I'm not sure why you say that. Every temperature profile I have ever seen has a controlled rate of ramp up, a plateau, more ramp up to max temp, a short hold followed by a controlled rate ramp down.

Maybe I haven't looked at enough detail? Is the ramp down very much faster than the ramp up?

--

Rick

not really, but if you don't have the fan to do the cooling automatically you have to manually open the door and try match the cool down profile

-Lasse

The ramp-up and soak is rather long, followed by a very quick 10C, or so, blip up, followed by a faster ramp down (faster than the ramp up). The ramp down only needs to be slow enough to avoid thermal stress. I'd think the blip in the middle, which has to be quite fast (10 seconds), would be difficult to do with a single oven.

No, it's not that different. It's just that it's hard to get the temperature to drop at the desired rate without a fan. You're pumping many hundreds of watts into it to get it to rise as fast as it should, you have to shed just as many to get it to cool at the same rate. If you allowed it to cool naturally, even without much insulation, I think it would violate the profile by a large margin.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

It's more a matter of my personal work style.

E.g., I've been baking cheesecakes the past few days. It's about a 5 hour process for each one (from start to "ready to deliver"). But, it is in sequential steps: prepare fruit (pineapple); refrigerate; prepare crust; refrigerate; prepare filling; assemble; bake; cool; refrigerate; "package". Each step brings you closer to "done" and is "finished" before moving on.

By contrast, baking *cookies* (pecan sandies) takes a comparable amount of time. But, the "bake" step requires preparing a cookie sheet full of dough, baking it (while preparing another sheet of cookies), removing the baked cookies from the first sheet while simultaneously inserting the second sheet.

Lather rinse repeat.

I.e., you're stuck in this annoying loop and can't move on to the next step (for more than an hour!)

Why not find an ultra tiny reflow oven and do *one* board at a time? :<

[We aren't keen on "surplus heat", here, as our "cooling season" is more than 6 months of the year. I.e., there is a big incentive to locate any such oven out in the garage just to keep that "extra" heat out of the living spaces.]

I'd been hoping for something with significant insulation in the walls (i.e., comfortable to the touch -- even during operation). One less thing to worry about injuring yourself, etc. And, conceivably, the sort of thing one could "load up", start and then *leave* (to complete on its own).

E.g., the kiln gets operated in a far corner of the yard just so it isn't "accidentally encountered" while in use.

I actually don't think there's anything wrong with that. I don't burn microcontroller code in a zillion at a time for small scale production.

If the end board it small you panelize it so you're only handling it once, including the baking. You *do* want an oven that will easily handle at least one of the largest *panel* you might want to use. If it's small stuff, a letter (~11" x 9") size might be just fine.

If the panel has 10 boards and it takes one minute each to inspect, program, configure and test each of them, you're not waiting for the oven.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

As I said in original post, I'm not looking at panelized designs. Rather, one of these, two of those, a couple of something else. I.e., I *could* do "one at a time". And each would be *different*.

When I bake cookies, I'm not waiting for the oven, either! I.e., remove the *baked* cookies from the sheet just taken from the oven; cut the dough and layout the next batch of cookies on this sheet *while* the "other" sheet is *in* the oven.

I.e., same sort of "always busy" activity.

I'd *rather* bake them all (cookies or PCB's) at the same time. Then, when they are *all* done, move on to inspect and test. (This was what I meant to illustrate with the cheesecake/cookie comparison)

E.g., while boards are being baked, clean up from that activity and prepare space for followup activities. Move from one *to* the next. If the cleanup takes longer than the "bake time", then I can stop/pause that activity without affecting the "next batch".

[I'm not an assembly line trying to push the most product through per unit time; rather, trying to do what is comfortable for me that will lead to the fewest screwups, etc. "Hmmm... did I finish testing this board?"]

It's gotten so easy to panelize that I do it when I'm only making a small number, unless the proto house is populated by the sort of coarse ruffians who would penalize you for panelizing. There's no point in getting fewer than a handful of boards in most cases anyway.

Don't forget to *enjoy*!

Having things physically organized seems very helpful, as is avoiding avoidable interruptions.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
Embedded software/hardware/analog  Info for designers:  http://www.speff.com