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Soldering again

why am I rubbish?

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Dylan Reynolds LaserCraft Services17/12/2012 22:30:34
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1704 forum posts
661 photos

What the hell am I doing wrong?

I studied several vids on youtube on how to connect deans to lipos and esc's, looks so easy......

......then i tried it, i can tin the wire and the connectors ok, but when i come to do the joint it just isn't happening, all I am succeeding in doing is making a huge pile of mess an not much else, I even succeeded in shorting a 5s 5A with a nice little firework display.

I have used several irons from a 40w leccy (as used in vid) to a cheap gas powered to a very expensive high powered dremel gas one, all the gas ones seem to do is melt the plastic casing on the connector

What is the big secret on soldering? I really think it is one of those black arts

ken hamer17/12/2012 23:12:41
1 forum posts

HAVE BEEN LOOKING FOR AN ARTICLE IN QEFI MAG BUT LENT IT OUT , HOW I DOIT IS TWIST THE BATT WIRES TOGETHER APPLY FLUX IT MELTS, THEN ADD SOME SOLDER TILL IT FLOWS THRU THE WIRES I USE BULLET CONNECTORS, STAND THE CONN ON END AND TIN IT WITH FLUX AND SOLDER , STICK THE WIRE INTO THE CONN APPLY HEAT TO SIDE OF CONN HOLDING SOLDER TO WIRE WHEN HOT ENOUGH SOLDER FLOWS DOWN INTO CONN WITH A NICE CONE SHAPE ROUND WIRE ,BEEN DOIN THIS FOR YEARS AND NEVER HAD A JOINT FAIL YET GOOD LUCK KEN

Martin Harris17/12/2012 23:22:41
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8728 forum posts
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Cleanliness, tinning, good mechanical connection*, sufficient heat, application of the iron to the work and the solder to the heated work, not the iron.

Unless pre-tinned with leadfree solder then always use proper leaded solder - and high silver content leaded solder gives the best results of all.

*The solder is there to hold the joint not provide the contact as it's not a great conductor.

P.S. When soldering batteries to connectors do one lead at a time and fully insulate the first connection before doing the second.

Edited By Martin Harris on 17/12/2012 23:34:18

WolstonFlyer17/12/2012 23:52:52
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2104 forum posts
189 photos
I tend to tin both parts quite heavily with proper leaded solder putting a bit extra on the wire. Then quickly heat the connector a bit to pre heat it, then bring the wire into contact and apply heat to just the wire until the solder on the wire melts and then melts the solder on the connector. Then do not move anything while it cools or you will get a weak "dry" joint that will look dull grey.

I hardly ever add any extra solder doing it this way as there is enough on both tinned areas to melt together.

It does take a bit of practice, I melted a few plugs first time. Don't forget to put your heat shrink on the wire before you solder the connector on.

If you are melting the plastic plug try connecting the other half of it together, that way there is more metal in contact to take the heat, if the plastic has gone a bit soft the pins are held in place by the other part of the connector until it all cools down.
kc18/12/2012 00:11:22
5954 forum posts
168 photos

Modern lead free solder needs a hotter soldering iron it seems. Buy a newer iron! Or buy proper lead solder from The Component Shop etc.

A gadget to hold the wires while they are soldered and while they cool should be used. Somewhere on Modelflying is a photo of a gadget made from bit of wood and 2 wooden clothes pegs. Also has holes for round connectors.

Biggles' Elder Brother - Moderator18/12/2012 00:16:04
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It really is cleanliness and heat (in the right place) that makes all the difference!

You say that you manage to tin the parts - but is the tinning bright silver and shiny, or is it a dull grey colour? If the latter it hasn't tinned. It may have solder on it - but that isn't the same thing at all!

In my experience 99.99% of soldering problems are caused by the two things;

1. The parts are not clean - really clean! If you handle the wire or the connector you're putting grease on it from your fingers all the time. If there is even the slightest bit of grease the solder won't wet that area. Simple as that. I tend to avoid any handling with my fingers if I can. If I really must handle it then I clean it with either a light brush with a fibreglass pencil and/or a drop or two of 9% acid flux applied off an old modelling paintbrush. My dad taught me many years ago - in soldering "cleaniless truely is next to godliness"! In fact a very good way to stop solder going where you don't want it to (for example when soldering a retaining washer on an axle stub) is to simple spread a little grease at the point where you want the solder to stop - it wont cross that point - and even if it does it will be possible to just break it off when cooled.

2. The second main cause is too little heat, or the heat in the wrong place! You have to get the workpiece hot - not the solder! The solder should melt because the workpiece is hot! Apply the iron to the work, then the solder to the work. You'll know straight away if its right because the solder will instantly flash right through joint at ligtening speed and it will be bright and shiny. As soon as it flashes, get the heat out of there.

WF is right - if you have tinned correctly then you should be able to form a mechanically good joint. But Martin is also right that unless the surfaces are pressed together there may be higher than desirable resistance in that joint. So pre-tinning is OK but you have to be able to press the surfaces together. For this reason I prefer to just hold them together and then apply iron and then the solder and just let the solder run through and around the joint. If its clean it will get into all the "nooks and crannies" believe me!

That really is all there is to it - the rest is just practice. It will seem tricky at first but suddenly it will just click - and then you'll wonder why you ever had a problem with it!

BEB

Stuart C18/12/2012 00:46:04
121 forum posts
4 photos

I keep a 2nd cut file (less its handle) flat on the bench, which I stroke with the iron to remove the clag. I then dip the tip in the flux and apply some solder to tin the bit. The surplus (if any) is shaken off, and now the iron is ready. Tinning the bit enables the heat to flow over a larger contact area, thus getting the temperature of the work piece higher more quickly, enabling the joint to be made before melting plastics further down the line. Well, that's my theory and it has always worked for me. Hope it helps.

Allan Bennett18/12/2012 08:24:22
1531 forum posts
38 photos

You say you've got a 40W iron, Dylan, but what size tip has it got? For heavy wire and a Deans Ultra connector (probably any connector, but Deans is my only experience), you need a chunky tip that once it's up to temperature will hold its heat when applied to what is effectively a large heat-sink. That way you should get a good flow of solder within two or three seconds.

I use one with interchangeable tips, so I can use 6mm for the larger jobs, and small ones (3mm or less) for PCBs and other small items.

Ernie18/12/2012 08:42:53
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2511 forum posts
20 photos

Hi Dylan, There is an excellent article on just this subject in a recent RCM&E (I can't remember which one) also there are quite a few tutorials on utube

ernie

Plummet18/12/2012 08:51:01
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1391 forum posts
41 photos

If you have a high wattage iron it can get TOO hot, but it can heat up a large lump of metal. Ule it on a small lump, and that will get too hot, Plastic will melt.

With a low wattage iron the lump will never get hot enough.

What you need ideally is a compromise, a large wattage but temperature (thermostat) controlled iron. These are more expensive, but make soldering SO much easier.

I am still using an iron that I rescued from being scrapped 30+ years ago. It has a magnetic thermostat mechanism that keeps it at just the right temperature for the old lead containing solder.

Plummet

malcolm woodcock 118/12/2012 10:40:57
396 forum posts

I would just like to add, if you want to tin a lot of wires, a solder pot can be quite useful.

Erfolg18/12/2012 12:05:11
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11313 forum posts
1121 photos

Bullet connectors should cause no problem at all.

Deans however can be a little more difficult.

The problem with Deans type is that you seldom have enough hands. To combat this, I use one of those hand free devices with a base, a few adjustable arms with crocodile clips on the ends.

The second issue, deans plugs use a thermo plastic, that is it melts, if heated above a certain temperature range. To help keep everything where it should be, you need both the male and female parts, inserted to make a single unit.

After that, you need to tin as you have done.

The next bit, which makes a difference, is to hold all the pieces, the wire, the plugs using the hands free as you want the finished assembly. With the wire applying a little pressure to the plug connector.

I now use a soldering gun, but anything with a broad, but thinnish tip will do.

I put the heated tip between the connector and the wire, so both are being heated. When the solder can be seen to liquidise on both parts, remove the iron carefully (I hold the wire, as it wants to move). Lightly press the wire onto the connector. The excess solder you tinned both parts with ensures that the joint has a good shape. Hold in place for about 30s., all is done. Simples.

Shaunie18/12/2012 16:49:44
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943 forum posts
78 photos

One big thing that seems to be overlooked with soldering irons that Plummet has just mentioned:-

If the soldering iron you own has no thermostat then it needs one important modification... snip off the lead and throw the lead and plug in the bin. You now have a valuable tool that used in pairs can be pushed into the ground to make a handy model restraint, or if you are also a gardener can be used as a handy dibber!

There will be those who say they have soldered fine for years without a thermostatically controlled iron, absolutely, I've been soldering for so long that I can make a decent joint with some solder and a screwdriver heated in a blowlamp flame if I have to, this is down to skill and practice. For those who do not solder regularly a thermostatic iron will improve your results beyond belief.

Once overheating is impossible due to the thermostat then the iron power can be safely increased. I use Xytronic irons at the moment as they are much cheaper than Weller gear and are rated at 60W, I'll work on surface mount stuff with these!

The trick is not in having a high temperature, it is in having a good heat flow at a reasonable temperature. To do this you need a sensible number of Watts, a thermostat and as thick a tip as you can reasonably use without being "clumsy". Weller do a miniature soldering pencil (and it is pencil sized) for SMD work, it is 90W rated, just can't afford one at the moment.

From memory CPC are offering a temperature controlled soldering station in the 50-60W range for about 40 quid, bearing in mind what we spend on this hobby of ours that's not very much.

Update: Just had a look in CPC's website, catalogue numbers SD01695 (£41.99), or for a little more money, SD01119, SD01117, SD01120.

Shaunie

Erfolg18/12/2012 17:04:23
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11313 forum posts
1121 photos

Having seen many rows of people soldering electronic components together, week in, wek out, using soldering irons without thermostaic control, I am a little perplexed as to the issue.

Oxidation will be faster the higher the temperature, yet oxidation does occur in the presence of oxygen even at low temperatures and no flux.

No, many, many, sucessful joints have been made with standard non thermostaic soldering irons.

Dylan Reynolds LaserCraft Services18/12/2012 17:33:11
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1704 forum posts
661 photos

Thanks guys, much appreciated and makes very interesting reading

After re-re-re-watching the vid on YT, the problem may be as mentioned above getting too hot and the wrong tip, i'm using a pointed tip, now the dremel iron comes with 6 different tips and not one of them is suitable for the job by the looks of things, also the don't make a flat tip for their iron, which seems very odd but there ya go.

Now it looks like another shopping spree, thanks for the suggestions of irons above, will certainly look at those.

Right now the important bit, because of my stupidity, lack of knowledge/skill etc, I did manage to short the lipo by accidently melting the shrink on one and bridged the connectors, it was a fraction of a second they made contact, there was sparks and a crackly sound, is the battery now bound for the bin? if it is i'm a bit more miffed than i was as its one of my brand new 5s 5000mAh 40c jobbies and not cheap as you all know, ah well you live and learn

Erfolg18/12/2012 18:04:53
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11313 forum posts
1121 photos

Dylan

Given you have so many tips, there may be one that you can modify and you cannot see a more important use.

I am assuming that the tip is copper or something similar. Just file the tip to the required shape. You will then have to put on the soldering iron, clean with steel wool,immediately coat with something like Fry;s non corrosive flux. Then heat up the iron and tin the tip, with cored solder, wipe clean on damp sponge. It is now ready for use.

WolstonFlyer18/12/2012 18:24:09
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2104 forum posts
189 photos
Dylan, you are lucky you didn't have that LiPo go "bang" if you dead shorted it.

You need to be very careful as a LiPo fire is nasty to deal with.

You will have to test it once you have the connector on, see if it balance charges ok etc, there may be some damage done to one of the cells.

Do you have a club mate that could help / give you a lesson?
Dylan Reynolds LaserCraft Services18/12/2012 18:45:47
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1704 forum posts
661 photos

Erflog - I would guess they are copper, coated with something as they look chromey lol

WF - Tell me about it, I have actually seen one go bang and trust me every single solitary hair on my body stood ion end and certain body parts disappeared inwards when mine shorted, was waiting for the big bang, but it never came (phew)

Unfortunately I live no where near our club or its members (I really do miss town life lol), untill I moved to this address this year I used to have to walk 2 miles to my next door neighbour lol

gliggsy18/12/2012 22:26:35
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97 forum posts
4 photos

Hi Fellas, I think one of the biggest mistakes with novice solderers is the fact that the iron should be kept away from the work and allowed to heat to temp' and then introduced to the workpiece allowing the transfer of heat at a quick, short blast therefore ensuring a good joint. Holding the iron to the work too long, before it's hot, is merely using the workpiece as a heat-sink, this will melt the plastic on the Deans and cause a poor joint......G

Martin Harris18/12/2012 22:52:37
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8728 forum posts
214 photos

I find a dab of solder onto the iron moments before applying it to the work helps the heat transfer via the freshly melted solder.

If you have a coated iron tip (the norm these days) you should NEVER file it - it will burn away rapidly if you do. What you should do is wipe the tip on a dampened sponge frequently to remove accumulated solder and flux residues.

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