Prototype oven recommendations

Hi,

I'm looking for recommendations for a small-ish oven for SMD prototype fab. Small boards (non-palletized). Probably just a couple/few square feet total board area at a time. No exotic processing, fancy controls, etc. Seldom used -- though I want it available "when I need it" (instead of sending off to a fab house "a la carte").

Operating it in a home environment so nothing beyond "220" (ideally, repurpose a stove/dryer or other "dedicated" service for it).

(No, I'm not keen on the EZ-Bake/"toaster oven" approach!)

Thx!

--don

Reply to
Don Y
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I have thought these would handle some heavy loads:

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Reply to
hamilton

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.

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Rick
Reply to
rickman

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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! :>

Reply to
Don Y

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

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
Principal Consultant 
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Reply to
Phil Hobbs

The advanced controller plus hand characterized toaster oven approach is tough to beat for that use case. The characterised aspect is rather important for best results.

?-)

Reply to
josephkk

For the occasional board, you might like to look at

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for their experiences using different techniques.

I've had some success with their "skillet" method, except I used

2mm of sand to spread/diffuse the heat, and monitored the sand/board temperature with a handheld non-contact thermometer.

For small single-sided SMD boards including 100-way mezzanine connectors, small 820uH inductors, leaded ICs with 0.3mm pads on 0.65mm pitch, I was /surprised at how good/ the results were.

I don't see any issues with using larger boards, other than the size of the saucepan.

As with all techniques (and probably different components) you'll need to hone your technique with a sacrificial example.

Reply to
Tom Gardner

Hi Don - One of our neighbors is extremely happy with this one:

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Good luck, Best Regards, Dave

Reply to
Dave Nadler

ROTFL! No, VERY sore subject! SWMBO has been increasingly hinting that I build a wood-fired one for the back yard. As we don't eat it often enough to justify that effort, I counter that we could simply have them shipped here from Chi-town and come out greatly ahead! As well as much better quality! :>

(building a wood fire surely requires a fair bit of "planning ahead"; why not PHONE AHEAD and just wait for the FedEx guy to show up with one?? :> )

Reply to
Don Y

Uh -- I don't think FedEx would ship a wood fire. They're kinda weird that way.

Seriously, though, if you had good enough temperature sensing you could probably do decent reflow in a pizza oven, as long as it has hot spots and cool spots.

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Tim Wescott 
Wescott Design Services 
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Reply to
Tim Wescott

I have a T-962A that I've used for several years. Probably put

500+ boards through it. I've lost count. Others bitch but I have not had a problem with it. The keyboard debounce is not great and a couple other minor issues but it does work.

It's not a $30K reflow oven so it does have some limitations. Temp control is OK but does tend to over shoot by about +10C when trying to ramp up. You can program 2 custom profiles.

Runs off 110V 15A circuit.

I have learned not to shove it full of boards. You have to subtract about 1" from the sides as keep out. If you go this route get the larger T-962A.

For me it was a buy vs build decision and buy won out. At the time when I bought it I simply did not have time to be screwing around with a toaster oven approach.

That's my story. Like I say, others bitch it's just Chinese junk and it does have some warts but it works for me.

I use Amtech LF4300 paste. If you are going to make more than just a few of the same board it is well worth the money to get a proto stencil.

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Chisolm 
Republic of Texas
Reply to
Joe Chisolm

No, pizza -- packed in dry ice. (actually haven't ordered one in a few years... :< )

... and you have a way of moving the kit around to seek them out, dynamically.

Reply to
Don Y

Argh!!! ------------------^^^^^^^^^^ s.b. "panellized" (I had to paLLetize a bunch of kit for shipment this week so got the wrong word stuck in my head! :< )

This seems a bit larger than the other unit mentioned in this thread -- closer to 1 sq ft. Still a bit smaller than I would like, though. (buy two??)

Is this a typo? "LARGER t-962A" (isn't that what you were describing already?)

I don't want to build. I don't want to use paste gun and Leister. I don't want to be in the board fab business. I don't want to save pennies and waste hours.

OTOH, I want to be able to assemble boards *when* I want them without having to send off to a fab house (esp for small quantities). But, I don't need to construct an "out building" just to house a small fab!

Most of my designs are small quantities - five or six pieces. Biggest (quantity) one is ~75 pieces. I am currently trying to merge designs and/or support differential stuffing to cut down on the number of layouts, etc. and drive the number of instances up. But, I am *sure* I will never get to JUST one or two designs... there are too many physical constraint differences as well as cost, performance, etc.

(optimizing designs also "wastes" my time, beyond a certain point. Easier just to settle on a reasonable compromise and let the quantities be what they may be)

Reply to
Don Y

After using a toaster oven with home-brew temperature control I bought a T-962. For the price I am very statisfied with it.

Same here. The largest PCB I put in it was a eurocard (100x160mm).

I totally agree.

Wouter

Reply to
Wouter van Ooijen

Of course. Think of the cache you could gain by reflowing your boards in a wood-fired oven.

--
Tim Wescott 
Wescott Design Services 
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Reply to
Tim Wescott

More interested in controlling how my *time* gets used than trying to impress the neighbors!

"Hey, Bob! I bet *you* can't reflow PCB's in *your* pizza oven!!"

Pizza-oven snobbery? :>

Reply to
Don Y

I have an extra one as a spare. Total cycle time for a board/panel can be in the 10 minute range with cool down. The good thing about the Amtech LF-4300 is the long work time. I can get >6 hours out of it. I have thought about using both ovens but I dont feel like running another 20A circuit. I could have one baking while the other is cooling down. The problem I found was not the time in the oven. It's the time to paste and stuff the board or large panel. I have a small air powered paste dispenser with a foot pedal. For dense and or large boards that gets old quick. I'm more than happy to spend the $100 or so for a stencil. Your time can go from 30 minutes squirting pads to 3 or 4 minutes. Sometimes it takes longer to clean up the stencil than to actually paste the boards.

Wish I had the volume to justify a setup like JL has out there in earthquake country. That's a sweet line.

I mean the larger T-962A vs the T-962.

Mine is on a small roll around cart in the garage. You will stink up the house if you use it inside (any oven technique). Need ventilation. For

Reply to
Joe Chisolm
[elided]

Have you had a need for it in that capacity? I.e., something breaking in the "primary" unit that necessitates calling on the "secondary"?

Yes. But you have to have a place to "accumulate" each stuffed board while awaiting their turn in the oven. I'd prefer to just use the oven's tray for that purpose. And, not have to *attend* to the oven by putting it "in use" before I've finished stuffing all of the boards.

[Returning to my cookie/cheesecake analogy: it would be A LOT easier to have 10 cookie sheets and an oven that could accomodate all of them (cooking each with the same general thermal characteristics) than to have to feed a new sheet into the oven -- and clear off the recently withdrawn sheet -- every 4.5 minutes! Or, shove them through on a CONVEYOR!!]

Yes. My current goal is to try to get the number of different artworks down so the "overhead" per design doesn't get silly. E.g., making qty *1* of a board starts to leave you scratching your head re: the costs involved.

Currently, I have only one design that *requires* qty 1. And, it's functionality/feature set is generic enough that I can probably

*buy* something COTS that is more cost effective from top to bottom (as long as I can get complete docs so I can code on bare iron).

But, there are still some designs that are qty 5 or qty 3... Amortizing a $100 stencil over 3 boards -- each with $20-50 of components -- just never feels "right"!

I don't want to build boards for a living. That's a *job*! :>

Likewise, I'm not fond of doing layouts. But, it's a lot easier than having to hover over another engineer's shoulder advising him of mechanical interference issues. Or, having to abandon a particular approach because "things don't fit" -- instead of being able to make a design change on-the-fly.

Rather, I will build boards (and do layouts) of necessity to be more agile in my design/fab process. Once "done", dispose of all the associated kit -- having extracted all the necessary value from it.

Ah, OK. I found a T962c which is apparently larger still. (I hadn't noticed the size difference between 962 and 962A -- I assumed the former was just a typographical omission)

I have a small room off the garage that I will probably repurpose for this use. Venting to the outdoors will be relatively easy. And, it is effectively isolated from the interior of the house. Easy to get necessary power. Etc.

Or, if that doesn't work out, set it out in the yard where the drop for the kiln is located. (i.e., it would be really nice to just be able to load up a drawer *ONCE* and carry it to the oven)

Did I mention "that's a JOB"?? :> OTOH, you get to see the real manufacturing problems that your design and layout pose. Far more helpful than offloading those problems to a fab house and never realizing that "a little tweak" could significantly improve the process/product.

My smallest boards probably barely fit the 100 pad criteria.

1.25" x 2.5" components double-sided. But, I need three (different layouts) or four to complete "one device/design" (i.e., I'm severely constrained on the overall device envelope)

And, there is a fair bit of followup work involved (thru-hole parts, socketed devices, etc.)

Mine (leister) is more than 20 years old. Bought it for one-off prototype builds and occasional rework. Well worth the investment. OTOH, not something I would want to make a career out of!

Yes. This only gets worse with age (vision, tremor, patience, etc.)

In my case, I may build "many" of a particular design, but seldom "all at once". E.g., it's one thing to buy enough bare boards to build 75 (or even *10*) of something. Quite another to also commit to the components and *assembly* before you have thoroughly evaluated and characterized the design!

OTOH, building *one* prototype of each is hardly worth the effort and expense.

I wonder if *any* "laser cutting service" could do a similar job?

Reply to
Don Y

I just can't see using a toaster oven. It reeks of amateurism. (like buying a $99 workstation! "How committed to this endeavor

*are* you, really??" :> )

Surely not a *single* board? Or, is that just all you needed to bake at that time?

I think if you are a business involved in manufacturing boards, you use a different set of criteria.

Similarly, if you are a hobbyist that wants to reflow *a* processor on a motherboard, game console, etc.

I'm somewhere in the middle. I don't want to save pennies at the expense of hours (or *scrap*!). OTOH, I don't want to be tied to a piece of kit that I then need to "feed, regularly" to justify the expense! Nor do I want to discover 6 mos or a year down the road that the fab was "marginal" and I've now got bits of kit failing that need AVOIDABLE rework. Or, that the *design* had a flaw that manifested after a lengthy usage period and now I have to refab those affected boards.

Reply to
Don Y

No, the total series was IIRC 60, but each board needed some afterwork, troug-hole soldering, and then testing, so why not put them in one at a time while I was doing the other work. The middle area of the oven seemed to work more reliable.

I do produce boards, but in very limited quatity (10's/year rather than

100's)

Wouter

Reply to
Wouter van Ooijen

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