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Old 05-19-2004, 10:05 AM   #1
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Default Worried about reliability of soldered connections

Solder and me do not seem to get along. Is there some gel, paste or liquid that is both conductive and adhesive that can be used as a replacement for solder.
------------------------------------------------------------------
What I find hard to believe is that people depend on solder in situations where reliability is critical.
A. Why would I want to press a hot soldering iron up close to anything electronic or electric. Why am I risking my batteries or my motor by heating up part of them hot enough to melt solder.

B. Why in an situation where I know an object will be subject to high speed impacts and sever jolts, major g forces do I want to depend on the adhesive properties of solder to hold 2 pieces of metal together.

C. If I wrap a wire around a post, or I have some kind of connector like a deans plug or a bullet type electric plug, I can look at the connection I can tug on the wire, I can actually test the level of adhesion or security of the connection. With a soldered connection I am always afraid of pulling on the connection and I have no confidence in a visual inspection.

I have had an “old pro” who seems to be an expert a soldering help me. In the last month I have lost 3 races because of his expert soldering ( battery pack bar connecting two cells failed, a soldered motor connection came off and a soldered wire from a deans plug to a battery failed.) All three connections looked good seemed good worked for a number of races but ultimately failed. It is possible this guy is a hack and not really very good with solder, but I am wondering if the dependence on solder as an adhesive in RC racing is not the over all problem.

------------------
My primary interest is reliability but I want to find a method which does not negatively effect the power of my car.
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Old 05-19-2004, 10:15 AM   #2
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Soldering isn't hard.....the biggest piece of advice I can give is to remember to heat the area you are soldering and apply solder to IT, not the Iron....you want the solder to flow to the piece, not the tip of the iron.

Use flux, its a chemical designed to aid the flow of solder.

You need a GOOD iron.....invest the $100 or so for a hakko, ungar, or weller of good quality. Get the part numbers off the ones you see at the local tracks that the fast guys use.

As for this old timer, dump him.....

In 15+ year of racing, I have never had a cell, motor, or battery come unsoldered.....

I can barely remember when the last time I saw plugs on a big racers car......they ALL hardwire. Plugs degrade as you use them and they cost $$$......hardwiring virtually cost nothing.

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Old 05-19-2004, 10:19 AM   #3
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Well, there are a few important things you need to effectively solder... the first of which is a good soldering iron...

If you're trying to use a 15W iron you bought for $10 at radio shack you're gonna spend 10 minutes heating up everything before it gets the solder to melt... if, however, you have a good, HOT iron, it'll melt your solder before you know it without overheating your batteries and electronics... There are plenty of decent irons out there... hakko, weller, etc

Just like any job, you need to have the right tool to do the job RIGHT.

The next part of the equation is practice... knowing how much solder is enough... I've seen tons of over-soldered and under-soldered joints in my day...both of which have their problems... the only advice I can offer is to not be afraid of trying and learning and FYI, a good solder joint should be able to withstand a good tug... it should withstand a hard crash as well...
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Old 05-19-2004, 10:20 AM   #4
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Solder is used everywhere as an electronic connection medium - open your computer and notice that nearly EVERY component is actually connected to your motherboard by solder.

Look in a car that has been in a wreck - a HUGE amount of G-forces and yet all the electronics remain connected to the boards they were soldered to.

I have had very very few good solder connections go bad, and I solder my batteries - I don't use plugs.

It sounds, to me, like you have a hack helping you. Your problem is what is called "Cold Solder Joints" where the solder has not bonded to one or the other side.

Just a couple of things -

first, you want a HOT iron. Sure, it's somewhat unintuitive, but if you have a good HOT iron, you put less heat anywhere but where you want the solder - you don't need to apply it as long so it doesn't spread as much. A cheapy Radio Shack soldering iron will work, but it won't be as good as a good Weller (the GOOD ones) or a Hacko. . . You'll be amazed with the difference.

second, once you have a good solder joint, you won't be able to separate the pieces short of a SERIOUS workout. With batteries, you should not be able to separate them short of utterly destroying the batteries and bars.

third, a solder joint can be and SHOULD be as strong as a mechanical joint (or at least close enough for our purposes).

Now - you can actually SEE when the connection is good. It should FLOW - nicely. If it's lumpy and "bulby" on the surface of whatever, then it's NOT CONNECTED. It should be a nice shiny smooth puddle, say, on the battery.

Here's a checklist for you:

1. Make sure all surfaces are clean. Solder does NOT like grease or dirt.

2. Make sure you have a good HOT iron. Solder needs heat and, actually, a hotter iron will do less damage to surrounding electronics, etc. than will a hot iron.

3. Don't drip the solder onto the joint. Heat the two joining materials together and apply solder to the joint - once it FLOWS (key is FLOW. . .FLOW. . .FLOW) into, between, and around the joint area, you're good.

4. Scuff any surfaces that you will be applying solder to - battery ends and motor terminals primarily. These surfaces will take solder better if they have a bit of a scuff - use a dremel or even a knife or screwdriver. . .just scrape a bit will do.

5. "Tin" both surfaces. This means apply a LIGHT coat of solder to both surfaces PRIOR to mating. For a battery or motor terminal, this means heating the surface until solder will melt and FLOW nicely onto it - coat the entire area to be mated. For WIRE - strip 1/4 inch, keep wire strands together (some like to twist. . .), heat the exposed end and apply solder to the WIRE, not the iron. Apply solder until the exposed wire is one piece, no individual strands, and the solder has reached the core as well. NOW mate both pieces and heat until the solder on both surfaces melts and FLOWS into each other (add a small amount of solder if needed. . .)

ExtremeRC, RCCA, etc. all have periodic articles about proper methods of soldering, with pictures, etc. I would do a google for them - in fact, here's ExtremeRC's "Advanced Soldering Techniques" - http://rc411.com/howtos/94/index.htm

Edited to add recommendations of things I missed, like a noob. . .ack!
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Last edited by Boomer; 05-20-2004 at 12:52 AM.
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Old 05-19-2004, 10:21 AM   #5
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I sucked at soldering myself until I learned how to do it. Its super easy an reliable now that I know how. The one factor that will make or break your solder job is "tinning" .(sp?) . You have to tin the wire and spot your going to solder before you solder the two together.

If your soldering a wire to motor, take the wire aside. Strip about an 1/8-1/4 of insulation off of it and twist the wires. Then take your soldering iron and hold it on the wire. Then once the wire is hot enough feed the solder into the wire. You'll see it when it happens. Then do the same thing to the motor lead. once that is done put the wire and lead together and hold the iron on the wire like a sandwich with the wire inbetween the iron and the lead. once its hot enough both parts will join together and make a pretty unbreakable connection.

Edit*** great point above, you should see the solder FLOW into the wire when tinning
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Old 05-19-2004, 10:42 AM   #6
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Default Re: Worried about reliability of soldered connections

Quote:
Originally posted by imjonah
Solder and me do not seem to get along. Is there some gel, paste or liquid that is both conductive and adhesive that can be used as a replacement for solder.
------------------------------------------------------------------
What I find hard to believe is that people depend on solder in situations where reliability is critical.
A. Why would I want to press a hot soldering iron up close to anything electronic or electric. Why am I risking my batteries or my motor by heating up part of them hot enough to melt solder.

B. Why in an situation where I know an object will be subject to high speed impacts and sever jolts, major g forces do I want to depend on the adhesive properties of solder to hold 2 pieces of metal together.

C. If I wrap a wire around a post, or I have some kind of connector like a deans plug or a bullet type electric plug, I can look at the connection I can tug on the wire, I can actually test the level of adhesion or security of the connection. With a soldered connection I am always afraid of pulling on the connection and I have no confidence in a visual inspection.

I have had an “old pro” who seems to be an expert a soldering help me. In the last month I have lost 3 races because of his expert soldering ( battery pack bar connecting two cells failed, a soldered motor connection came off and a soldered wire from a deans plug to a battery failed.) All three connections looked good seemed good worked for a number of races but ultimately failed. It is possible this guy is a hack and not really very good with solder, but I am wondering if the dependence on solder as an adhesive in RC racing is not the over all problem.

------------------
My primary interest is reliability but I want to find a method which does not negatively effect the power of my car.
What I can't believe is you're arguing against soldering. It's a basic fundamental skill in this hobby. Solder is not an adhesive, solder permeates into the molecular structure of the material and forms a common bond which joins the metals together.

The so called pro doesn't know how to solder, that's the problem. He's probably using a cheap setup that can't get hot enough to do a proper job. Soldering is not an adhesive process!
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Old 05-19-2004, 10:54 AM   #7
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All I can say is WOW! This "ol' pro" guy really gave you a bad impression. Sorry for the bad news but yup...soldering is essential. Here's a nice primer from my other hobby:



1. Use a good flat chisel-type point

2. ONLY use a grounded iron for electronics work...

3. Let the iron always get really hot before you try to work... (wait 6 mins)

4. Get a stand for the iron if you don't already have one...

5. Get a "helping hands" stand with the two alligator clips, it really helps hold the wires, etc...

6. Go slow...

7. Always flux the two things you intend to solder together with a dab of flux...

8. Always tin the tip of your iron and use a damp sponge to keep it clean while working. A bit of flux on the damp sponge really keeps the iron clean.

9. Last but not least...ALWAYS use heatshrink tubing to cover bare connections, as you don't need to short out your $300.00 graphics card because you goofed while measuring voltage.
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Old 05-19-2004, 11:08 AM   #8
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everything has been pretty much covered the only thing I would add is make sure that you get 60/40 Rosin core solder, it's much easier to work with than other types, also I find it much easier to use the liquid flux, the paste is kinda messy.
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Old 05-19-2004, 11:08 AM   #9
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If you stay in R/C you WILL have to learn how to solder sooner or later, so you might as well start now.
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Old 05-19-2004, 12:01 PM   #10
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Go to deans plugs!
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Old 05-19-2004, 12:16 PM   #11
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Quote:
Originally posted by Charlie O
Go to deans plugs!
you have to solder the wires to the dean plug. no way around soldering.
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Old 05-19-2004, 12:43 PM   #12
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Yes, but you only have to solder once. I think he is worried about soldering the motor, and battery all the time and getting a bad connection, if he only has to do it once, it lessens his chances for a problem, and deans makes a pre soldered female connector.
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Old 05-19-2004, 12:55 PM   #13
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If u wan to be fast in racing, you need to practice, practice and yea ... practice.
Same goes with soldering.
Practice, practice and MORE practice.
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Old 05-19-2004, 01:25 PM   #14
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Quote:
Originally posted by fatdoggy
If you stay in R/C you WILL have to learn how to solder sooner or later, so you might as well start now.
I agree with this, but if you run nitro touring car, no soldering is necessary right off the bat. Everything plugs into the receiver
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Old 05-19-2004, 01:42 PM   #15
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Quote:
Originally posted by jackhammer74
everything has been pretty much covered the only thing I would add is make sure that you get 60/40 Rosin core solder, it's much easier to work with than other types, also I find it much easier to use the liquid flux, the paste is kinda messy.
Quite right, & the only things I'd add are to make sure that the tip of your iron is of decent size & is nice & broad, the more tip surface area you have, the more quickly it can transfer heat(which also helps to prevent the objects you're soldering from overheating), & it's also a good idea to LIGHTLY scuff the surface of what you're soldering, if possible, Like on motor tabs & batteries, I'll use my Dremel with a sanding drum & use it at low speed to scuff the surfaces I'm going to connect, that seems to help a bit in giving the solder something to grab onto, as well as clean off any residues that may have been there from when it was manufactured. When you do it right, the solder joint should be nearly as strong as the materials you just connected, so only heating it up to a temperature hot enough to melt the solder would cause it to break....
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