DIY Reflow soldering

This is related to this question.

I'm trying to get started with a DIY reflow soldering station intended for my personal use. I'm planning on starting small and improving the system as time goes on (basically just the unit to begin with and better temperature control as time goes on).

I'm thinking of getting this 1000W hot plate. It has decent reviews and at $20 is pretty cheap, too. I would like the setup to be able to handle lead free solder paste, though I'm not sure if I'll go that route to begin with. I have 2 questions: What pros/cons should I consider when choosing between a hot plate/skillet or a toaster oven? The two I've identified so far are: 1. for the same rated wattage hot plates/skillets are cheaper (~$20 range vs. ~\$30 or higher)
2. According to Sparkfun toaster ovens might melt plastic parts, though I wonder if this may be due to user error/flawed designs.

My second question is related to temperature and power. The devices I've seen are rated in Watts, not maximum temperature. From what I've read a decent reflow system should be able to reach at least 230-260C if it's intended for lead-free work. However, I'm not sure how this translates into what wattage to be looking for.

Anyone with experience have recommendations on what power ratings I should look into and any other factors I should consider?

• I was very impressed with a lab-style hot plate I saw in use: a dead flat thick surface (almost looked like stone) made for even heat/transfer. Also having no edge on it made it easy to slide small boards on/off using the same tweezers we were using for SMT parts, and to look at things in profile. A "skillet" where the heated surface was surrounded by edges wouldn't have that. – Chris Stratton Sep 30 '12 at 18:19

I reflow in a Skillet. Most skillets and toaster ovens I have seen go to 350-400 Farenheight, which I don't think is enough for lead free solder.

The real benefit of a skillet is you can watch the parts on the whole PCB as they reflow, so you are not depending as much on your temperature profile being right. You can see the solder paste first turn a grainy/shiny and then shiny. I also use an infrared temperature gun to maintain the right temperature for soaking.

In my case I had to buy a piece of plastic and put bolts in the corners for leveling the skillet. I also had to run a fan on the skillet after reflow because it didn't cool quickly enough.

• Any advice on wattages I should be looking into for a skillet/hot plate? – helloworld922 Oct 1 '12 at 15:19
• I shopped at Walmart and bought the maximum temperature for the surface area I needed. Maybe you could convert wattage to temperature and shop that way. Otherwise, you could buy the most watts you can afford. Evenness of heating is important, so don't go too cheap. If heating is uneven, then you will have to get a aluminum plate. – BSEE Oct 2 '12 at 18:26

Components designed to be reflowed will not melt in an oven. If a connector is too fiddly to solder by hand, then it's probably designed to be reflowed. If it's hand-solderable, then you can just hand solder it and not worry.

Having said that, I have seen some connectors discolour in an oven, especially after the second bake, which looks kind of unsightly. In this respect a skillet will be better than an oven.

If you're going to be making PCBs with components on one side only, then go with the skillet. It's cheaper, therefore you don't have much to lose if you decide you don't like the results. I've seen people solder boards this way, and it clearly works.

At work we use an oven because we need to do PCBs with components on both sides. That way works too.

• Any advice on wattage? It seems like either method could work with hot plates and skillets being the cheaper option. – helloworld922 Oct 1 '12 at 15:18
• "If you're going to be making PCBs with components on one side only, then go with the skillet" Does oven allow 2-sides reflow? If bottom contains elements, wont they fall off when reflowing the top? – Vadim Chekan Jun 1 '13 at 1:20
• @VadimChekan - Amazingly not. Most small components, chips included won't fall off the bottom. They're held on by the solder, even when it's melted. Large chips, like PLCCs might fall off. I haven't tried them. – Rocketmagnet Jun 1 '13 at 20:31