Before you start to solder using a toaster oven, you will need several tools and items. This article describes what is needed for the process, including a modification to the oven, various tools, and a description of how to make a low cost vacuum pickup tool.
The first item is the toaster oven. You can use any kind of toaster oven, but generally I would not recommend the very small ones. The medium sized ones seem to work best. Whichever one you get, it must have a glass door on the front so that you can see what is happening inside the oven without opening the door.
You will also need a digital thermometer and a thermocouple. You can buy these from your local electronics store.
The thermocouple looks like a long wire with a connector on the end. The connector end plugs into the digital thermometer outside the oven, and the other end goes around the edge of the oven door and into the oven cavity.
It is also important to have a stopwatch, so that you can monitor the time as the temperature changes inside the oven.
You will need to make the following modification to your toaster oven so that your boards do not get toasted by direct infra red radiation from the heating elements.
The objective is for the heater elements to simply heat the air inside the oven, so a direct line of infra red heat straight from the elements to the circuit board must be avoided.
The way to achieve this is to get some thin sheet aluminium and make a cut-out shape that just covers up the elements. You can use a disposable baking tray from the supermarket to make this aluminium shield.
The aluminium sheet can be attached by weaving it through one oven the oven rack slides. This will hold it in place.
Make one of these aluminium shields for both the top and bottom heating elements inside your oven.
The next item is a solder paste gun. This is the easiest way to apply little dots of solder paste to the surface mount pads for the chip components.
I use AIM solder cream, but any kind of lead based solder paste is suitable for this process. You can purchase a solder gun and solder paste from your local specialist soldering equipment supplier. I purchased these items from Okay electronic solutions here in Australia.
Now we will discuss how to make a vacuum pickup tool from a small fish tank air pump, which you can get for about ten dollars from your local aquarium shop or pet shop. I will describe the way that I made the modifications.
I removed the case of the air pump so that I could access the air inlet hole of the pump. Then I simply fitted a small plastic nozzle that I got from a syringe dispenser. Attached to that is a short length of 3mm vinyl air hose, which I got from the aquarium shop. Then another nozzle made from metal, which came from another syringe dispenser.
You can get these nozzles from your local specialist soldering equipment supplier. The nozzles generally come with some syringe dispensing kits but you may also be able to purchase them separately.
To use this low cost but effective vacuum pickup tool, simply turn on the pump and bring the nozzle down onto the top of the chip component. The component will be sucked and held onto the end of the nozzle. Then bring the chip component over to the circuit board pads which have been dotted with solderpaste. Place the component down. The solderpaste is sticky enough to grab the component and hold it in place. No vacuum release is necessary.
That covers all the items that you will need to solder using a toaster oven, including a modification to the oven, various tools, and a description of how to make a low cost vacuum pickup tool.