Soldering Advice #1

SOLDERING INFORMATION & ADVICE #1

The Black Art de-mystified

Part 1: The right stuff!

A little about Soldering, Soldering Tools & Solderable metals

What is soldering?

Here are a couple of “ex web” definitions – all accurate, but they really describe only the “what”, but not the “How” of soldering…..

#1: A technique used in making or repairing items whereby two pieces of metal are joined by applying a molten metal which has a lower melting point than the two metals being joined.

#2: A process that is used to bond similar or dissimilar materials by melting a filler metal or alloy that is placed between the components being joined. Solders are generally filler metals or alloys that melt at temperatures below 450 degrees C. (Above this temperature the process is usually termed “Brazing”, and uses very different materials and tools)

HOW does Soldering work?

Soldering is a process by which two metals or alloys are joined together with a third metal or alloy.

The third metal or alloy is the solder, and has a much lower melting point compared to the first two metals. Soldering is different from adhesive joining.

Adhesives bond by mechanical attraction having to do with mechanical surface properties of the material relative to the adhesive. In the case of solder, there is also a chemical reaction in addition to physical reaction.

Soldering is primarily used to provide a convenient reasonable strength joint, to ensure electrical contact or seal against leakage. Solders typically do not provide overly high mechanical strength, given the soft nature of popular solder materials. Soldering is used extensively in the electronics industry printed circuit boards. It is also used in joining metals in hobbies and in industries such as cutlery, tools, metal box making etc, where its strength is more than adequate.

The Soldering process bonds by creating an Inter-metallic Layer.

In order to have a good soldering joint, one must form the thinnest possible inter-metallic layers between the solder material and the base metal. Otherwise, the solder simply solidifies over the base metal without forming any bond (The “dry joint” familiar to all in electronics manufacturers).

Within each inter-metallic layer, there are actually a number of different compounds formed by the solder materials and the base metal. These compounds are typically quite brittle and will adversely affect the integrity of the solder joint. As the joint is subject to stress, thermal cycles, vibration, or shock, the inter-metallic layers are usually where it fails.

Why should you consider Soldering?

Mechanically soldering is usually fast, strong, waterproof & shock-resistant compared to glues… as well as being generally impervious to most solvents. Because it utilizes materials of a similar surface texture to those it joins, it can form a contiguous surface that is easy to finish invisibly and paint well… In other words, its neat and tidy!

Of course, if we are talking electrical or electronic products soldering is the ONLY way to reliably connect items to a PCB or circuit automatically and at low cost.

However… there are a few other VERY important reasons for the modeller to solder:

A. Because it is the ONLY way to achieve some forms of joint in scale modelling (Try fixing rungs to a scale sized ladder with glue…. Or invisibly fixing fine detail to a brass loco…. Or building signals using scale materials or a loco chassis or trackwork or perhaps a series of fine fences).

B. Because once simple skills are learned, it is MUCH EASIER quicker and far stronger than glue for most hobby applications

C. Because it is faster, more permanent and more refined than making models with Glue.

D. Because working with metal and solder allows for second attempts and makes errors more easily corrected than glue or any other form of fixing ever can.

A 4mm scale English prototype Royal Scot locomotive, soldered together from brass and nickel silver components. Even the connecting rods are each made from three parts, inner, centre and outer, in order to reproduce a scale thickness and shape that is totally correct.

Advanced work yes, but something that every one of you could do if you read these pages carefully, make sure you have the right tools, take your time and follow kit instructions carefully!

Soldering tools and their uses:

Basic soldering requires only a few tools.

For once most of them except for a good soldering Iron are quite inexpensive but if the modeller wishes to do a good job they must be correct for the job. Get in the habit of using them with every task (in particular the simple ones like a damp sponge) and you’ll soon be routinely making the perfect solder joint!

A quality Soldering Iron:

A good quality soldering iron of a size that can be handled precisely AND with adequate power to heat the job rapidly PLUS a tip of the appropriate size/shape to deliver the power where it’s needed… ONLY where it’s needed: High quality doesn’t necessarily mean expensive - In this context it means well designed so it can do the job properly!

When choosing a Soldering Iron, it is VERY important to understand the difference between heat and temperature.

It is a complete misunderstanding of the soldering process to think that a smaller soldering iron or lower power iron is needed for smaller tasks or for “lower temperature” soldering jobs. The temperature to which the bit can be heated is only an indication of the potential level of the Irons output – The actual ability of the Iron to deliver adequate HEAT to the joint in the minimum of time will be the measure of the Irons quality.

In all cases the best result will come from the ability to deliver the right amount of heat at the right place as quickly as possible. This will ensure that fluxes can do their work properly, that solder can flow and bond properly and will result in minimum collateral heat damage to the parts being soldered PLUS the lowest possibility of damaging other parts or materials or (dislodging adjacent parts).

Simplest example for railway modellers: soldering “droppers” to rails in plastic track – we want a fast, small, unobtrusive joint with NO heating of sleepers or rail fastenings as this causes very ugly visible damage, changes gauge & weakens track.

Therefore the “perfect Iron” is one that is powerful enough to do ANY soldering job and small enough to be handled precisely. Ideally it will have (a) excellent temperature regulation (b) rapid heat delivery to maintain consistency (c) allow the both operating temperature range and (d) either the tip or Iron itself to be changed quickly and conveniently for extreme differences in use. This ability to change is important – ie: tiny for SMT electronics, larger for “heavy metal” use.

When it comes to soldering irons, like may things in life it is not the biggest or most expensive that wins, it’s the RIGHT Iron that wins, and that’s always no more or less than the most appropriate type for the task in hand. An expert or an average modeller can all do a good job with a good iron, but nobody can produce a good result with an inadequate one.

To see the temperature controlled soldering Iron that was used to make the locomotive we showed you earlier on in this page, and the several other soldering Irons that we recommend very highly, CLICK HERE

A Soldering Iron Stand

You have to put it down sometimes and it needs to be somewhere safe. If you’ve ever wrecked a model by accidentally letting the iron get close when you put it down for a moment or leaned on a hot Iron with your arm you’ll understand why in no uncertain terms.

A good soldering Iron stand will have a heavy solid base for stability, a soldering Iron holder that will hold the Iron properly AND shield the hot tip. It should also have a sponge holder in the base to hold a damp sponge for tip wiping before every joint!

If you’d like to see what one looks like, or need one for your workbench, then please CLICK HERE

Please note:

High quality soldering Irons, especially temperature controlled Irons, may come with there own stand included in the box… so if you are purchasing a new Iron, check before you spend more than you need by buying one separately.

A Damp sponge.

This is to keep the tip shiny and clean while it is turned on, between solder tasks. Ideally it should be a natural sea sponge but these are expensive!

You can happily use a normal kitchen sponge as long as it’s kept very damp. Just place it on a saucer or similar!

A quick wipe of the tip on this before EVERY use of the Iron will ensure best results for each joint as the tip will stay clean and shiny for best heat transfer speed.

A fiberglass pen or abrasive cleaner:

Cleanliness is at the core of good soldering and that means removing hard oxides and surface treatments to get a good joint.

Fluxes are in effect powerful cleaners but flux alone can’t do this on some materials and anyway, a fiberglass brush is the easy way to do the initial cleaning quickly and cleanly on many jobs.

Generally available at reasonable cost, they DO wear down quite rapidly but most have an easily replaceable “brush insert” so it’s a one-off reasonable cost with a low maintenance cost.

We have them ex stock: CLICK HERE

A Clean & Flat soldering surface:

Soldering can be harder than it needs to be if you can’t see what you are doing, and if you can’t hold items in the correct relationship to each other, so a good practical work surface to solder on is just as important as it is for any other form of modelling task. We are fortunate in that a material that’s VERY common makes the perfect soldering surface – Melamine covered chipboard.

This is the white coated chipboard usually used for Kitchen cupboards etc… It is usually available as off cuts (free if you ask nicely) from any kitchen maker’s premises, and is often available at a good price from “Steptoe” type yards.

Use a good thickness (usually 12~15MM). White is usually best.

It’s easily marked out with squared lines and the melamine, although very thin is smooth and VERY good at handling chemicals and heat – the perfect hobby bench surface really.

Its cheap so don’t be afraid to drill it or tack on bits of timber to give a guide or work-fence to solder against.

Clean regularly with anything that will remove residues and chemicals – it’s very tolerant and anything from a bathroom cleaner to MEK will do it well.

Assorted Clamps and “Holding materials”.

There are lots of options here, but avoid plastics for obvious reasons. Here are a few that are low cost and very useful.

Disposable: * Balsa Glue (dries almost instantly, and spotted in place can hold two bits of metal long enough to solder them) * Blue-tack * double sided Sellotape * wooden clothes pegs (they can be carved to shape to fit your current need).

Long life: * Dolly grips” – these are the long straight Aluminium hair clips that ladies used to use to hold rollers in their hair when they had a “Permanent wave”.

Perfect as customizable clamps (they are bendable) and REALLY good as “heat sinks – clamped on close to a joint to absorb heat and stop previously made joints coming unstuck. * Low cost mini-clamps from the dime, pound or dollar shop * steel bulldog clips from the stationers.

A “Scrawker” or scraper.

I’m not really sure where the strange name came from… but it’s nothing exotic!

A scraper can be made from an old scalpel blade, snapped hacksaw blade, by snapping a piece off a worn needle file or something similar – it’s used to get into tight or right angles to remove any excess solder and give a perfectly square corner, usually where there’s a tad too much solder where cab-side meets footplate for example.

Useful sources of this sort of thing are everywhere – needle files, broken scalpel blades etc… use your imagination.

De-soldering Wick.

The sophisticated way to remove excess solder. This is made with a pure copper “braid” in many widths. Place it on the joint and place the soldering iron firmly (but not too hard) on top of it.

It will suck up excess solder and clean up a PCB or clean off a brass model.

Dipped in flux its an excellent way of cleaning up accessible surfaces that have accidentally received too much solder…used with care it’s the perfect way to clean up seams in whitemetal models, but DO be careful about overall temperature when doing that!

When the job is done clip off and discard the “solder filled part” ready for next use.

We carry de-soldering wick ex stock. Click here to see it or buy: CLICK HERE

Soldering Iron Tip cleaner.

With a solid base and brass “wool” this is used to clean burned flux residue and oxidization from the soldering iron tip and keep it totally clean. Excellent to use before and after soldering to keep the Iron in “best” condition. You CAN use other means but the fine brass “wool” is clearly best for stubborn muck or to remove excess solder when changing solder types (Important when changing from low melt to normal solder for example – some solder alloys just do NOT mix well).

Tweezers & pliers of various shapes.

Holding metal without pain is important... heat travels quickly through some metals and you’ll find that you run out of pain tolerance just before the solder hardens quite often if you do not have some means of holding things other than your fingers. Actually any plated tweezers will do, but avoid untreated mild steel or brass as it’s likely to end up soldered to the job in hand.

I also find a selection of bamboo skewers or Satay sticks and wood scraps helpful here – and there’s also the best of them all – a long fingernail, “gods gift to those that solder fine work” as a finger tip/nail is very sensitive to positioning things properly so it can be super accurate, and it doesn’t transfer heat …plus it is constantly growing ready to use (Which is useful, as solder heat + fluxes makes them brittle… ask me how I know that).

** In these well groomed days I don’t expect you to grow talons, but sharp fingernails were once useful cutting & marking out tools for the “older trades” too – I once knew an old saddler that used to sharpen his thumbnail and use it to cut kangaroo hide into long leather spirals to make the most beautiful plaited bridles reins and whips!

Do you have any more interesting ideas? – Do let us all know …. I’m presenting this to YOU but I’m still always happy to learn, because constantly gaining new knowledge is the ONLY way I can get better at what we do!

Solder types and when to use them

I once spent hours creating some notes on soldering to present at a club meeting. One attendant scanned them and blustered “I got a soldering kit from my daughter for my birthday and I can do anything I need with that – why are we wasting time on this”.

The same “deaf to improvement” person told me not long after that he was replacing his flex-track with set-track because “its impossible to make even curves otherwise”… and still seems to find it hard to open the boxes his trains are sold to him in as well…

All in all a genuine shame as that same man loves his hobby and would enjoy it so much more with FAR less frustration if he’s only accept a few simple things. (As it is, as far as I know, he still hasn’t used the soldering Iron of course…..)

I mention this because I’m often told that “60/40 standard solder is just fine” and there’s no need for any other.

Well… that’s simply not the case. One of the BIGGEST problems you have in soldering is that the same solder will NOT do the job in all cases.

We need to consider the metal that will be soldered, the conditions it will be used under, the need for strength and the need for flow.

General Solders:

60/40 is the standard solder sold in hardware stores....

It’s usually flux cored and is a very good “general solder”. It is composed of 60% tin and 40% of lead; this solder melts at appx 190^oC/374^oF, but doesn't become completely solid until it cools to 180^o/361^oF. This means it has a "pasty range" or "working range" of 7/13 degrees.

The liquid temperature and narrow "pasty range" can make it easy to form and maintain consistent high, rounded, beaded joints, such as on electrical work, however its long “pasty” time also means that if you don’t hold the work perfectly still for several seconds after making a solder joint, a “dry” or imperfect joint will result.

63/37 is a better choice for most “standard” work electronic work though… (sometimes called “Eutectic” solder)

That’s’ because it has two properties that are better than 60/40.

It makes a stronger joint AND, more importantly, it goes from solid to liquid AND back again over a very narrow temperature range…. Meaning it can make a much faster joint that is much more likely to be perfect. It’s therefore excellent for electrics/electronics BUT it has poor flow characteristics for tasks other than simple electrical/mechanical joints.

50/50 is the better choice if you want to have the solder flow smoothly…

as when making a seam or “tinning” two bits of material ready to join them with solder. It melts (depending on additives) between 182 and 188 degrees. We sell a superb 188 degree solder from Carrs that has exceptional flow and “wetting” properties.

Add a little silver….. and you get the DCCconcepts favourite!

We LOVE the solder we created for use under our own label as it has all the best properties of all of the above. It is stronger than 60/40, its slightly better as a conductor so is perfect for electronics & electrics, it has quite a low melting point of 179 degrees with a VERY FAST melt transition just like 63/37 and it flows beautifully just like 50/50. All because we added some silver to the 63/37 mix.

It works well on almost anything actually… many of our clients love using it on their brass kits too, as it flows really well and makes a fine, strong joint on all the harder alloys such as copper, Brass and Nickel silver. In combination with our own flux, it will also very easily solder spring steel or piano wire, and even most grades of stainless steel!

It is certainly the BEST solder for attaching wire to rails, bar none!

We call it “Sapphire 179” and it is available now: CLICK HERE

More DCCconcepts “Specialist solders”:

Many tasks will be covered by “general solders” and with the fluxes I now have available I do find myself using our own really superb DCCconcepts 179 solder for many kit building tasks, however there is NO doubt that there are tasks that really do need the correct specific solder for the job, as only the right solder will work best in many applications… so with our success in creating Sapphire 179, we went a little further and created two more excellent solder products.

DCCconcepts Sapphire 145 solder

While developing our 179, we also talked to our Mfr about the importance of smooth flow with kit-building and the need for a fine solder wire to aid precision, and they came up with another winner… our “Sapphire 145”. Very similar to the Carrs 145, it has a very slightly different formulation and we are delighted to say, has the best performance of any solder we have ever used in kit-building… The difference in flow and its ability to go where its wanted with zero “wicking” or peaking has been noticed by the experts, In fact, it is now used exclusively by a couple of the UK’s better professional loco builders, despite the fact that in bulk, its more than twice the price of its nearest competitor.

For more information on our Sapphire 145 solder, please click here.

DCCconcepts Sapphire 100 whitemetal solder

Finally, we have just approved yet another exclusive DCCconcepts Solder—this one took a while to get right, but our new “whitemetal” solder has some really nice characteristics…

Its melt point is 100 degrees rather than 70, however unlike 70 degree solder, it can be applied directly to brass to attach whitemetal parts with NO need for pre-tinning with normal solder!

Its due for delivery July 2009, so click here to see if its ex stock yet!

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CARRS Solders

Much of the info below is from the Manufacturers website… with snippets of added data based on our own experiences… which with Carrs products are always positive!

We also use Carrs products extensively on our own models and kits and love them, so in line with ONLY selling those things we are happy to use ourselves, we are delighted to also stock a range of Carrs Solder products as follows:

It is available here: CLICK HERE

Carrs 70:

This is the standard “Low temperature solder” for the assembly of whitemetal castings. It is sold in bar form and one pack will last for more than one whitemetal loco kit or many whitemetal accessory soldering jobs.

The solder melts at 70° C but when fully fused with whitemetal it re melts at a higher temperature. As this solder does not have good penetration qualities, when soldering whitemetal to brass or nickel silver, you should ‘tin’ the brass with a 138 or 145° C Solder before soldering the parts together.

Whitemetal often contains a high proportion of Antimony, which reacts badly with Zinc, a constituent of brass. (Antimony is an essential ingredient of some low melting point solders. The drawback is that it makes joints brittle. Tinning helps to avoid this problem.

NB: What we call ‘whitemetal’ is a Low Temperature Alloy for Centrifugal Casting. The melting rage varies from 125 - 285° C, so you really should be able to ‘undo’ a white-metal kit by immersing it into a bath of very hot water.

It is available here: CLICK HERE

Carrs 145:

This is 145° C solder is normally used for detailing. This enables you to add the small parts to an otherwise completed structure with a reduced risk of melting the main joints and other details. Its lower melting temperature also means that less heat is required. It should be used with the appropriate fluxes for the metals being joined. It should be noted that Carrs 145 contains Cadmium and care should be taken over its use.

It is available here: CLICK HERE

Carrs 179:

This is a Tin/Lead/Silver solder….very like our own 179 solder.

Solders containing silver have brilliant ‘creep and flow’ characteristics, making them ideal for laminating. Perfect for all electronic circuitry, they are also suitable for tinning of aluminium and some zinc rich alloys – like the casting metal used by Hornby Dublo, or that of US made models which is called Mazak. (When used with Carrs Grey Label Flux or DCCconcepts “Alloy & Hard to solder” Flux).

NB. As aluminium absorbs a lot of heat, it needs a higher iron heat transfer rate than for brass. Soldered aluminium is highly susceptible to corrosion; therefore it is important to seal all joints from the atmosphere within an hour or so of making them. Carrs Electrofix is ideal for this purpose…. As is a quality general purpose automotive undercoat.

NOTE: The high heat needed and the aggressive nature of aluminium fluxes is very hard on soldering irons. DO it if you must, but perhaps a soldering torch is the best tool. To be honest, we really don’t think that aluminium is a suitable modelling material unless it can be glued.

Carrs 179 is available here: CLICK HERE

Carrs 188:

Under-used as it’s a great solder to use… sometimes its especially nice to have a solder that really flows well leaving the tiniest possible fillet at the joint, and this solder flows beautifully for long seams and tinning of parts. This is ideal for soldering sheet metals and close fitting joints.

The short melting range minimizes the heat required and thus the risk of distortion. Low surface tension means that only a small fillet is left along a joint, it also flows more readily than less pure common solders

Carrs 188 is also available as a solder cream which is VERY convenient to use for attaching detail parts or when sweating together complex etched laminations where minimal solder will always give a better result.

It is available here: CLICK HERE

Carrs 224

This is the same basic formula as 'Tin-man's Solder', but with a low antimony content so as to be suitable for use with brass.

It has a longer melting range than No. 188 and a higher surface tension (it stays “plastic” longer). It also tends to hold shape well, and so this makes Carrs 224 solder useful for filling gaps, as when making fuel tanks or supporting bearings in oversize holes to obtain precise location.

Some railway modellers like to solder locomotive chassis with this, as the fillets strengthen the assembly. For the same reason, its not good for detail attachment.

It is better for joining solid or higher stress components together than No. 188.

It is available here: CLICK HERE

Carrs 243

The high melting range of 235-243° C makes this useful when further soldering is to be done nearby.

You should then be able to continue without the worry of earlier soldered items beginning to bubble, melt and become un soldered. (such as soldering loco assemblies that will later have details added with 145 or perhaps turnout “common crossings or frogs” which will later be soldered to copper-clad sleepers).

The reverse is also possible… as in when you need to solder small parts onto the larger pieces, before the main assembly. For the creators of kits, it is ideal for soldering up masters and sub masters for assembling masters for white-metal castings. It flows very well (The flow characteristics are similar to those of No. 188).

However, Note carefully: it should not be mixed with other lead solders as it may become brittle.

It is available here: CLICK HERE

SOLDER CREAM – 139 degrees (Perfect for conventional soldering irons)

It is available here: CLICK HERE

SOLDER CREAM – 179 degree (Ideal for resistance soldering, excellent with conventional Irons too)

It is available here: CLICK HERE

The introduction of this 138 & 179 degree cream has may well revolutionise the construction of etched brass kits and many modellers now use little else.

Everything about it is good. The particle size is right; the particle shape is right; the resin flux is the best we have used. It is supplied in syringe, together with a micro nozzle, which allows you to apply the very minimum amount you need.

Consequently, the work is neater and cleaning up is but seconds work. The 138 is ideal for adding detail. The Solder Cream is particularly suited to the use of Resistance Soldering Units.

This is a special note for the brave. One particular application for the more skilled modeller is the using of 138 Solder Cream for fixing white metal castings to brass or nickel silver.

Whilst it is normal “Conventional wisdom” to use low melt solder to fix whitemetal castings to each other, some folk feel that the normally accepted practice of tinning the brass first with Tin/Lead solder and then using a low melt material, produces a joint that is fundamentally weak. So, for fixing whitemetal castings to brass or nickel silver, you clean both surfaces, mate them together, smear a small amount of 138 cream onto both surfaces and flood the work with Yellow Label Flux. Touch the brass immediately adjacent to the whitemetal and remove the bit the instant you see the solder starting to flow. The result is a strong clean joint. You can use the same technique with lost wax castings.

However, you ARE working closer to the melting point of some whitemetal, so please test with a scrap piece and ensure you are comfortable and able to properly control the application of heat to the model before soldering in this way.

An Important note about Solder Creams to “occasional solderers”:

Solder creams are expensive compared to solder and flux and they are also relatively short lived, so consider carefully before purchasing them unless you will use them up within a short time...

Once opened they will start to deteriorate and the solvents will slowly leach out. At the very least they must be stored in an airtight bag and kept in the refrigerator to have any reasonable shelf life.

LEAD FREE SOLDERS:

Because of the problems created for the environment in the recycling of electronics, recent global legislation has made it illegal to use lead bearing solders in many applications especially where assembly is via a production line or factory process. HOWEVER Hobby applications (and all military products) are excluded from this onerous change – which is a good thing as to be frank it is far harder to solder well with the current generation of lead free solders!

We DO however wish to make the point that with leaded solders now being produced in far lower volumes, we CAN expect significant price increases over then next decade PLUS inevitable shortages in the lower temperature solders

(These also contain some quite specific and quite dangerous products like cadmium, so are only made by very few specialist companies)

SOLDERING ON “FACTORY MADE” LEAD-FREE PCB’s

Lead free solder does NOT mix well with leaded solder. If you are repairing or adding to a PCB made in the last few years it is likely to have been created with lead-free solder. If you do not want to buy lead free solder just for this job that’s OK… BUT Before re-soldering a new part in place thoroughly clean off the solder pad with de-soldering braid or a “solder sucker” plus a fiberglass burnishing brush and make sure there’s not enough lead free solder left to compromise the leaded solder you are using.

Solderable Materials.

Things you CAN solder given the right technique, solders, tools & fluxes:

Despite the “fear of soldering” and the denial of many modellers that it can be done, basically almost all of the commonly available modelling metals are quite readily soldered with little difficulty by the average modeller using average tools, providing he uses the right techniques, the correct flux AND the correct Solder.

Easiest of all to Solder:

Tin, Copper, Steel, Brass, Nickel Silver, Steel alloys.

A wee bit harder but still relatively easy for the average modeller:

English Whitemetal, lead, Pewter. Spring Steel.

Difficult without special fluxes and techniques BUT not impossible:

Iron, Stainless Steel, Aluminium & its alloys, Zamac & its derivatives.

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There are two more pages of soldering information. If you would like to go to the next page directly, simply click on the link below

Do you have other questions about soldering? No problem – just click here to email us and ask, we’ll be happy to help!

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