T-962 Reflow Oven Custom Profile Calculator | Voltlog #339

In the last video I showed you how I upgraded the T-962 oven to fix some of the issues that were present on this oven. I also mentioned that there is an option to configure a custom reflow profile with this oven and that’s probably something you’re gonna have to use sooner or later because there are so many options of solder paste on the market and not only that but also there is variation between different ovens so it’s likely you’re gonna have to tweak that.

So in this video I’m gonna show you how to define a custom reflow profile in the open source unified engineering firmware.  Before doing any actual configuration on the oven you need to start with the specs of your solder paste. For this example let’s assume we are working with the NP545 series from Kester, we need the datasheet of this product to check out the recommended reflow profile. Inside the datasheet we can find the recommended graph, it’s an unusually small one for this paste but luckily we can zoom in and increase the size of the graph.

At this point I recommend you grab a screenshot of this profile and import it into your favorite img editing tool because we need to draw some lines on this graph to extract some values. First I added a scale on the Y axis with a line at each 5 points. Then I added these lines to plot the absolute values on the Y axis. So we now have a set of temperature values for every 30 seconds of the profile but the firmware on the oven, the procedure for inputting a custom reflow profile expects data points every 10 seconds so we need to somehow extrapolate our values to generate more points in between.

T-962 Reflow Oven Upgrades & Fixes | Voltlog #338

This is the famous T962 reflow oven coming from China, you might find it under a bunch of different brands, it’s available to order directly from China but also from a bunch of local distributors who are importing these ovens but in general they all have this list of problems which can be easily addressed for improving the performance as well as the safety aspects of operating one of these.

I got mine for about $180 shipped from Germany so there was no tax involved and it got here pretty quickly but you can probably find it for less if you are willing to wait a bit longer and get it from China. I used to run my own reflow oven based on a toaster oven but trust me, unless you invest in a really expensive toaster oven you’re not going to get the same performance as with one of these dedicated ovens. They’re not perfect as I’m gonna show next, they still have a bunch of problems but once we address those problems it becomes a decent oven with superior performance when compared to a toaster oven.

So let’s start with the paper tape insulation problem. This oven uses glass wool for insulation of the hot chamber and to seal that they used a combination of aluminium tape and paper tape, it really looks like the cheap painters tape. Now obviously the insides of this oven are gonna get hot and that paper tape is gonna start to burn and it will release fumes and a nasty smell. If you buy this oven and start using it right away without implementing this fix, you will need to vent that room most certainly. 

Luckily this is an easy fix, the only thing you need is kapton tape. The idea here is to equip yourself with a pair of gloves and place the oven on a table that you can wipe clean when you’re finished to avoid contamination with the fine particles released by the glass wool. It’s best if you have some genuine kapton tape because it will stick better and you will have to remove all of the paper tape and replace it with kapton tape. You might also find some pieces of rigid cardboard/paper like material in there, I wrapped those in some kapton tape as well for protection against the heat and inserted them back where they were. Your oven should look something like this when you’re done.