T962 Reflow Oven?

[jpanhalt]

I was seeing 10° to 15°C differences in temperature left to right using independent thermocouples/thermometers (see post #48).  That was with a slow fan speed.   After I increased that minimal speed to 20, the difference got smaller (post #49), but I didn't save those notes.

[EE-digger]

Since the Unified Engineering firmware exposes offsets and gains for left and right TC channels, I decided to take a closer look at these before tossing this thing out a window.

With a third TC mounted between and at the same height as the chamber TCs, I adjusted the offsets on a cold chamber, then adjusted the gains with temp set to 200C.  With this simple adjustment, tracking was perfect between left, right and the third TC.

The real problem with IR, especially with a chamber this small, is deciding upon a reference board on which to set up a profile.  Without stirring the hot air, the IR has too many variables, from reflective gold to board density (plane layers), etc.

I now think the oven can be put to pretty good use, once you set up a profile based on the needs of the paste AND the characteristics of your reference board.  Repeated assemblies of the same type should be a breeze, provided chamber uniformity (i.e. size) is considered.

Thanks for you reply but I've gone ahead and ignored left to right delta for the moment.  I think there are bigger fish to fry ... ok, bake

[Roger_Ramjet]

What leaded and lead free solder are people using in T962? Should you go for a low temp lead free solder to improve chances of reflowing? Thanks

[jpanhalt]

I use Kester EP256 63/37 tin/lead.

I only use leaded solder and have no experience with lead-free low-temp alloys.  They presumably are based on bismuth or indium and tin alloys.  The former is less expensive and probably more common.

[Southerner]

https://github.com/UnifiedEngineering/T-962-improvements/releases

to get the hex file but there is no hex file there that I could find.

Click on Assets to expand the list and you'll see a link to download the hex file
https://github.com/UnifiedEngineering/T-962-improvements/releases/download/v0.5.2/T-962-controller.hex

That github page is 9 years old.  I do not see a releases page but the latest still seems to be the V0.5.2 that you linked.  Is there anything newer?
Thank you.

[Kean]

That github page is 9 years old.  I do not see a releases page but the latest still seems to be the V0.5.2 that you linked.  Is there anything newer?
Thank you.

The last "official" release 0.5.2 was in Feb 2008 but it works reasonably well considering the (significant) design limitations of the oven.

Releases page: https://github.com/UnifiedEngineering/T-962-improvements/releases

There are some pull requests and issues on that repo which list additional mods people have come up with.  And there are 174 forks, so plenty of people have created other versions and you're welcome to dig through all of that to try find something that suits you better... but you will likely need to set up a suitable compiler and so on.

[girts]

That github page is 9 years old.  I do not see a releases page but the latest still seems to be the V0.5.2 that you linked.  Is there anything newer?
Thank you.

That oven was designed and is sold unchanged from 2005.
About SW updates on git - why? If everything works as promised?

[Southerner]

About SW updates on git - why? If everything works as promised?

Because it does not work as promised. That is why this thread is so long as many/most of us that own the T962 get temp excursions all over the map and major temperature variations depending on where you measure it inside the T962. the mods (if I read them correctly) were designed to fix that.

[jpanhalt]

I don't believe the firmware mod was designed to fix problems with uneven heating.  There are still just 2 TC's and minimal circulation in the oven.  The mod allows better user control and a genuine "cold" junction correction.

The mod also allows relatively easy calibration of the TC's to a reference measurement and adjustment of the heating profile.  On mine, tracking of the actual temp to the profile is relatively close.  Actual undershoots the peak a little, but 63/37 solder relows fine, so I haven't messed with it.  Increasing soak time might help, if you are having problems.  I ran a blank run before doing my boards, but I don't know whether that made any difference.

Another factor is the small drawer v. big drawer version.  Mine is the small drawer.  I would expect more problems with the bg drawer version.