Prototype oven recommendations

On Thu, 04 Sep 2014 12:02:34 -0700, Don Y wrote:

> 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

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.

-- 
Chisolm
Republic of Texas

Hi Tim,

On 9/5/2014 9:33 AM, Tim Wescott wrote:
> On Fri, 05 Sep 2014 06:32:17 -0700, Don Y wrote:
>> On 9/5/2014 5:28 AM, Dave Nadler wrote:

>>> Hi Don - One of our neighbors is extremely happy with this one:
>>> http://tinyurl.com/dn37gm
>>
>> 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??  :>  )
>
> Uh -- I don't think FedEx would ship a wood fire.  They're kinda weird
> that way.

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

> 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.

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

Hi Joe,

On 9/5/2014 10:31 AM, Joe Chisolm wrote:
> On Thu, 04 Sep 2014 12:02:34 -0700, Don Y wrote:

>> I'm looking for recommendations for a small-ish oven for SMD prototype
>> fab.  Small boards (non-palletized).  Probably just a couple/few square

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!  :< )

>> 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!)
>
> 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.

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??)

> 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.

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

> 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.

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!

> 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.

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)

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

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

> I have learned not to shove it full of boards.

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

> 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 totally agree.

Wouter

On Fri, 05 Sep 2014 11:11:12 -0700, Don Y wrote:

> Hi Tim,
> 
> On 9/5/2014 9:33 AM, Tim Wescott wrote:
>> On Fri, 05 Sep 2014 06:32:17 -0700, Don Y wrote:
>>> On 9/5/2014 5:28 AM, Dave Nadler wrote:
> 
>>>> Hi Don - One of our neighbors is extremely happy with this one:
>>>> http://tinyurl.com/dn37gm
>>>
>>> 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??  :>  )
>>
>> Uh -- I don't think FedEx would ship a wood fire.  They're kinda weird
>> that way.
> 
> No, pizza -- packed in dry ice.  (actually haven't ordered one in a few
> years...  :< )
> 
>> 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.
> 
> ... and you have a way of moving the kit around to seek them out,
> dynamically.

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

-- 

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

Hi Tim,

On 9/5/2014 12:00 PM, Tim Wescott wrote:
>>> 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.
>>
>> ... and you have a way of moving the kit around to seek them out,
>> dynamically.
>
> Of course.  Think of the cache you could gain by reflowing your boards in
> a wood-fired oven.

<grin>  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?  :>

On Fri, 05 Sep 2014 11:26:28 -0700, Don Y wrote:

> Hi Joe,
> 
> On 9/5/2014 10:31 AM, Joe Chisolm wrote:
>> On Thu, 04 Sep 2014 12:02:34 -0700, Don Y wrote:
> 
>>> I'm looking for recommendations for a small-ish oven for SMD prototype
>>> fab.  Small boards (non-palletized).  Probably just a couple/few
>>> square
> 
> 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!  :< )
> 
>>> 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!)
>>
>> 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.
> 
> 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??)
>
 
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.
 
>> 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.
> 
> <frown>  Is this a typo?  "LARGER t-962A" (isn't that what you were
> describing already?)
> 

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

>> 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.
> 
> 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!
> 

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 <100 or so pads per board, a paste dispenser is not too bad.  I use
one of those portable air tanks.  It will last longer than my butt will
take sitting there squirting boards, but it still gets old quick.
The dispenser is tucked away on the work bench. I have done the hot air
gun thing.  I'm glad it just sits on the shelf now.
  
>> 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.
> 
> 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)

I have found that trying to do QFNs or .5 pitch is difficult without a
stencil.  Others report they can do this small but I always get too much
paste and bridges.  If I'm going to, even "someday", do more than 10 of
some board I get a stencil.  It just makes life so much easier.
I generally use Stencils Unlimited.  Never had a problem with them.
Upload your paste layer gerbers and 4 or 5 days later UPS shows up.
I have noticed a lot of the board houses are now offering proto stencil
service.  I think they all just send it out to the same place.

-- 
Chisolm
Republic of Texas

Hi Joe,

On 9/5/2014 1:04 PM, Joe Chisolm wrote:

[elided]

>>> 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.
>>
>> 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??)
>
> I have an extra one as a spare.

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

> 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.

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!!]

> 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.

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"!

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

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.

>>> 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.
>>
>> <frown>   Is this a typo?  "LARGER t-962A" (isn't that what you were
>> describing already?)
>
> I mean the larger T-962A vs the T-962.

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)

>>> 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.
>>
>> 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!
>
> 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.

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)

> For<100 or so pads per board, a paste dispenser is not too bad.  I use
> one of those portable air tanks.  It will last longer than my butt will
> take sitting there squirting boards, but it still gets old quick.

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.)

> The dispenser is tucked away on the work bench. I have done the hot air
> gun thing.  I'm glad it just sits on the shelf now.

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!

>>> 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.
>>
>> 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)
>
> I have found that trying to do QFNs or .5 pitch is difficult without a
> stencil.  Others report they can do this small but I always get too much
> paste and bridges.

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

> If I'm going to, even "someday", do more than 10 of
> some board I get a stencil.  It just makes life so much easier.

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 generally use Stencils Unlimited.  Never had a problem with them.
> Upload your paste layer gerbers and 4 or 5 days later UPS shows up.
> I have noticed a lot of the board houses are now offering proto stencil
> service.  I think they all just send it out to the same place.

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

Hi Wouter,

On 9/5/2014 11:34 AM, Wouter van Ooijen wrote:
>> I have a T-962A that I've used for several years.
>
> After using a toaster oven with home-brew temperature control I bought a
> T-962. For the price I am very statisfied with it.

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??"  :> )

>> I have learned not to shove it full of boards.
>
> Same here. The largest PCB I put in it was a eurocard (100x160mm).

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

>> 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 totally agree.

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.

>> Same here. The largest PCB I put in it was a eurocard (100x160mm).
>
> Surely not a *single* board?  Or, is that just all you needed to
> bake at that time?

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

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

Wouter