October 2016
I’d like to dive into doing surface-mount projects. I’ve heard of people using a regular toaster oven for soldering. Will an off-the-shelf oven work or is a special temperature controller required for a satisfactory result? Or, would I be better off just soldering by hand to start?
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There are circuits to control a toaster oven to make a reflow oven, but I get decent results using a normal toaster oven and the following procedure:
I am this very moment seeking the same solution you are for a variety of surface-mount (SMD) projects. I also have a cheap unused toaster oven just waiting to heat things up!
Two temperature control approaches are readily available, with one being more complicated with PIC processor and other components. I am “Old School” and not yet experienced with programming these, but I located a nifty Nuts & Volts article about a toaster oven controller. This article appeared in NV’s June 2008 issue, authored by Kit Ryan, entitled “Oven Flow 1.0.” I just printed the article out after hunting through my .pdf collection of NV. You should give this a read because K. Ryan covers the essentials of reflow soldering SMD devices. Important for success is knowing and maintaining the proper Time vs. Temperature profile. The temp ramps up, levels off and then ramps down all under processor control. Kit also refers to SparkFun’s Electronics Reflow Toaster Controller for toaster ovens!! Another reference is to Kester’s SMD soldering time/temp profile (kester.com) and I plan to read it: you should too.
The 2nd least complicated method is analog and manual. Should you mount a readily available barbeque thermometer inside your toaster, you’ll be able raise/lower inside heat and time the temperature transitions with a watch. I understand this not-very-fancy-at-all method and notice my grill’s temp gauge reads up to 700 degrees F. That’s more than enough range to see SMD solder paste melt. My grill’s gauge is a replacement I bought in the BBQ section of a local big box store and is not expensive. Now all I need is patience and a working clock!
Toaster ovens are used for surface mount soldering. Usually there is a temperature profile that is used. Sparkfun Electronics made a kit that you could use to control a toaster oven but they don’t sell it anymore. You could probably find the temperature profile on the net and do it manually. You can also use a heat gun to solder surface mount devices by putting solder paste/solder flux on the pads and then heating up the board with the heat gun. I have found this to not be reliable, especially if there are other parts already soldered on the board.
Another way to do it is manually. If the PCB was tinned when it was produced, it is possible to tack down a few key pins on the board and then solder the rest. This requires a very fine tipped soldering iron, very small diameter solder, and a lot of patience, but it has worked for me.
A few other notes. Getting the solder paste/flux onto the board without bridging adjacent pins is tricky. Often times, a stencil mask can be made when the board is produced. They make it easier to get the solder paste /flux down accurately. However, they come in various quality levels with the good ones being higher priced.
For one-sided boards, electric skillets are known to work. You also need a pair of tongs to get the board in and out quickly. If you simply turn the skillet on and wait for it to heat, the flux will burn off before the solder melts. Unfortunately, I presently have a workbench full of boards with components on both sides. For me, it's back to the soldering iron.
