I suggest it might be helpful to consider a small variation to Guy's back to
basics route, which is to use a multimeter connected directly to a t/c.  ].
This will give you a direct reading on the meter which you can read off as
temperature using a*thermocouple reference table* which you can Google or
get from a physics book. Compare with your datapaq readings. This will
probably be slightly easier method. With a watch you could even plot some
curves!

As to the capacity of the oven. If you mean literally how many boards can
you process, this will obviously depend on the conveyor speed and loading.
For loading on a small, small zone count machine like the Dima I would
suggest you think in terms of one board per zone at any time. This will give
you a theoretical number - if you knew conveyor speed. 
I think you probably had capability in mind also and the two are connected.
The capability will depend on the amount of Delta T you can tolerate and
still achieve acceptable results - probably slower on heavier, complex
boards. That will mean some empirical tests.
So running the two together you should be able to come up with some numbers
which will enable you to make an assessment on your capability/capability
and compare to projected workloads if done in house.



Regards

Mike Fenner 
Bonding Services & Products
T: +44 [0] 1865 522 663 E: [log in to unmask]

 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey
Sent: Wednesday, February 15, 2012 6:05 PM
To: [log in to unmask]
Subject: Re: [TN] IR Reflow Oven capability

Hi Howard,

I agree with Dave but you can characterize your oven with the DataPaq. And
if you are on a tight budget you can verify your Datapaq, before you have it
calibrated. 

Put the thermal couple in a bead of solder. Then heat the solder with an air
rework station or on a hot plate. Watch for the solder to change phase. 
And verify that the thermal couple reads 183C or 361F. Put the thermal
couple in boiling water for 100C or 212F. Compare the thermal couple reading
at room temperature. If the instrument tacks well at these readings it
should work okay for your needs. 

Next, mount thermal couples across a large wide board and measure the top
air and bottom air temps through the oven. 

Then, mount thermal couples under a standard part (those QFPs for example)
and place them across large wide board an measure the top and bottom side
variation. 

Finally, mount the loaded couples in a diagonal so you can monitor the
response as the zones are loaded. Do the parts at the front get hotter than
the parts at the back, compared to the results from the previous test.

This should give you confidence or reason to reject the oven for your
applications.  

Guy

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Watson, Howard A
Sent: Wednesday, February 15, 2012 10:44 AM
To: [log in to unmask]
Subject: [TN] IR Reflow Oven capability

Hello all,

Wow, after an 8 year hiatus from the electronics industry, and the Technet,
I am surprised to see so many familiar names still active on the Technet.  I
see this as a testament to your wisdom and staying power, something I didn't
have!

In my new job, in a very small shop of R&D quantity, I see that we have a
very small IR reflow oven that is seldom used (most of our boards are
entirely hand soldered or contracted out).  The oven is a ~15 year old bench
top oven with a heating tunnel that is 3 feet long - 4 heat zones.  The
reports I hear are of  "hit-or-miss" quality output, which might not
necessarily be the oven and could be the process. Our boards can be complex,
multi-layer and with some large QFPs, big ground planes, etc.  My question
is: does anyone have direct experience to share regarding these small bench
top IR reflow ovens, and did/do you have a positive experience?  For the
record, the oven is a DIMA SMT Systems SMRO-0252.  We use 63/37 solder, RMA
flux.  We do profile the boards, but since the datapaq has not been
calibrated in 10+ years, I look at these profiles with some suspicion.  Your
feedback will help my decision process to keep the oven and work on the
process, or work on getting a new oven.  As always, I appreciate your
insight!

Howard Watson



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