This post is the old version of the T962a Reflow oven upgrade documentation. A more up to date version of this post with additional information and pictures can be found in the 1BitSquared forum. The following text is being left here for historical reference. 😀
Many people ask on a regular basis what Reflow oven I am using. To answer that question I use two fully upgraded/modified T962a reflow ovens. You can get them from ebay for around $300 give or take. I heard some people had some success using toaster ovens with modifications for reflow but I personally do not trust that solution enough from not only the safety standpoint but also from the ability to follow a reflow temperature curve in a repetitive manner that I can trust. That also means you will need the T962a and not the less powerful T962, you will need the power to be able to reliably follow a reasonable reflow temperature curve.
That said the T962a is completely useless when you get it and you need to make a few modifications to it. If you do not make those modifications you will create a safety and health hazard. Also you will likely burn up your pcb’s or evaporate the flux from your solder paste before it reflows creating cold solder joints.
The closest thing that I could find that could be an out of the box working replacement is about 10x more expensive than the T962a including the modifications.
This are the supplies you will need:
- Screw driver
- medium width Kapton tape
- Small file or other scraping device
- A serial to USB adapter. (and FTDI cable is a good choice)
- Soldering iron
- A little bit of wire
- Thermocouple interface board with parts (https://github.com/UnifiedEngineering/T-962-improvements/wiki/Better-thermocouple-interface)
- A small replacement “silent” 40mm fan
And these are the following steps you need to perform to modify your oven.
- Open the oven
- Remove all the masking tape and replace it with Kapton tape (pay attention to the masking tape that is hiding under the insulation in the front of the oven attached to the “ruler” shaped cover above the oven’s drawer, you need to replace that too)
- Make sure that the whole case of the oven is connected to the earth ground of your power connector using the multi-meter. You might need to scrape off some paint under the back panel screws to create a connection between the earth and the bottom half of the oven.
- Re-flash the controller board with the Unifiedengineering firmware: https://github.com/UnifiedEngineering/T-962-improvements/wiki
- Build the Thermocouple interface board and mount it in the oven: https://github.com/UnifiedEngineering/T-962-improvements/wiki/Better-thermocouple-interface (you can use the oven without the TC interface to reflow the TC interface, but it might be better if you have some other place you can reflow the board in, but it should work for that one time :D)
- Replace the small cooling fan for the controller electronics with the new “silent” fan.
If you have all the supplies that modification should take no longer than one afternoon and it is really worth it!
Notes about usage:
- Pre-heat the oven to 40C before use.
- Put down scrap PCB material under the board you are reflowing so that it is not sitting directly on the metal tray. If you don’t do that the tray will suck out valuable heat out of your PCB and cause problems.
- Use only the center 1/3rd of the oven tray. The outer area of the reflow tray will not have the same temperature as the center and you will have consistency issues around the edges of your PCB’s. This is a good reason to design your boards as small as you can so that you can squeeze a bunch of them into the center of the oven. ;D
Hope this helps.