Soldering Iron Temp and Techniques

This weeks Tip of the Week is about soldering iron temps.  I was once again at the Outback Shootout hosted by The Outback Raceway in Chico, Ca this past weekend. As per normal I was there for support and to get in some racing of my own.

During nearly every event there will inevitably be a new person or racer that I will meet. This conversation generally starts out with “Are you Randy Pike?”  This is generally followed up by a second question one of which is “Hey I blew up my esc hooking it up backwards, can you help?” or “Can you help me solder this up?” I of course enjoy meeting new people but rather prefer the latter question over the first one! LOL

Rx8 Soldering

So joking aside, I get asked to solder all sorts of things.  Esc’s of course, battery pack connectors, starter boxes, as well as switches and servo leads.  Here are some guidelines that I follow having learned the hard way(often the best way in my opinion) soldering all these items.

1. What gauge is the wire I’m soldering?

  • If you’re soldering 18awg wire, you’ll use far less temp than say 12awg wire. In general if I’m soldering on small awg wire like 20-16 I’m likely around 400-600f on the temps. If I’m soldering anything larger I generally go for 750-1000f on the temps.  If the insulation of the wire you’re trying to solder immediately begins to melt or pull back from the area your tip temp is too high, turn it down. Now there is still the consideration of what you’re soldering this wire to. Keep reading…

2. What am I soldering to the wire?

  • If you’re soldering an 18 awg wire to say a servo pcb or esc pcb, you MUST think about the thickness of the board and the size of the “pad” or area that the pcb has cleared for the solder/wire to adhere to. The thickness of the pcb can draw temps from the tip of your iron so take that into account.  If you’re soldering a 12awg wire to a heavy connector such as a deans or EC style, more tip temp will be required for a proper joint.
  • If the pcb is a “through” design these often are easier to do IF you take the time to clean the hole. Regular “non-thru” pads require a bit more finesse since you really have to focus on holding the wire in the right direction while soldering the joint properly. Patience is key here. Take your time, don’t rush, and prepping the area before the job are key.

3.  How do you prep the area/items?

  • Clean the two surfaces you’re joining with the solder joint. This means cleaning wire if it’s dirty or greasy, same goes for the connector or pcb. I use rubbing alcohol most of the time with a clean tooth brush. Note that grease or dirt will contaminate the joint and render it not fit for racing.
  • If you need to clean old solder from an area there are a few ways to go about doing this. To clean pcb’s for example tools such as a solder sucker or solder “braid” work great. The sucker tool is nothing more than a vacuum bulb used to suck the solder away while it’s in liquid form. Solder braid is generally copper braided wire that will “wick” any solder it comes in contact with once the iron is applied.  On larger solder joints you can also use the “heat/tap” method which is heating up the area with solder on it, for example a Rx8 Gen2 solder post. While the solder is in a liquid state hold the item upside down and “tap” it on a table top or other solid object just enough to dislodge the solder. It takes a bit of practice but once you’ve master it, it’s super quick. NOTE: Yes liquid solder is HOT!  Don’t be “that guy” and message me saying you burned yourself with the “Liquid Hot Magma” <Dr. Evil Voice>

4.  Tools and items I use for good solder joints

  • Currently I’m using the new Hakoo 888 iron. I had a 936 up until just recently when the baggage handlers decided I needed an upgrade(don’t ask).
  • I use Miniatronics Rosin Core Solder 60/40. I’ve NEVER had a solder joint fail due to bad solder using this stuff and swear by it. I’ve used Radio Shacks brand before but have had spools that just seemed like crap and had to chuck ’em.
  • I’m sure I’ll start a fun conversation here, but I DO NOT use solder flux.  Flux of course promotes a good clean solder joint but if you prep your stuff right,  I don’t feel we need it in this application. If you have a good iron, clean items, good solder there’s NO excuse for getting a poor solder joint.

5.  Practice, practice, practice.

  • When I was younger and learning to solder I’d use anything I had laying around to practice on. I used to build bulb dischargers for friends, solder and re solder old battery packs, you name it.  Speaker wire is pretty cheap and works great for practice, and NO it’s not great for your rc car.

I’ve done a video on the Tekin Racing YouTube page showing some of these techniques. Be sure to check it out here:

Also a few options to solder our new RSX here:

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