WELCOME!WELCOME!

The Art Of Soldering

Tips & Techniques To Improve Your Soldering Skills

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This is an EduTRAIN™ Clinic

EduTRAIN™Copyright © 2014, National Model Railroad Association, Inc.

PLEASE Set Cell Phones to Stun!

“Soldering is an interesting activity because it normally requires at least one more hand

than most of us come with.”

-- Jack Hamilton, Tool Car, Feb 2014 NMRA magazine

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“There’s nothing difficult about soldering.It just takes a little practice.”

The problem is knowing WHAT to practice.

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What Can You Expect From this Clinic?

1. It is assumed that you have tried to solder something at some time in the past, and that it probably resulted in some amount of frustration for you.

2. This clinic is derived from the training material that is used to teach soldering to electronics manufacturers building electronics for the military.

3. The key techniques are presented that you need to know so that you can be successful at hand soldering. The goal here is to help you improve your skills in the Model RR hobby.

4. This clinic will “bust” some of the myths about soldering that you see every so often in various articles about soldering.

5. This clinic is intended only for soldered electrical connections.1

6. This clinic is not intended for soldered mechanical connections2; both use the same techniques, but the differences are that:

- A more active (acid type) flux may be used- The Solder alloy may be different

1 See the February 2007 issue of MR, “Ready…Set…Solder!”2 See the July 2003 issue of MR, “The Lost Art of Soldering”

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I. MATERIALSI. MATERIALS

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What Is Solder?

SOLDER is a fusible metallic alloyused to join metal surfaces without

melting either surface.

SOLDERING is the processof creating permanent interconnections

between electrical components.

For electrical soldering, the tin-lead alloynormally used is either:

63% tin + 37% lead (Sn63)-or-

60% tin + 40% lead (Sn60)

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• Flux used for electrical soldering typically use natural rosin as a base. Rosin is derived from pine tree sap, and has a light brown color.

• Flux is inert until heated, but when heated, it activates and removes surface oxidation that occurs when you heat any metal.

• Flux comes in different forms: Liquid, Solid, Paste, or contained within the solder wire itself (called “flux-cored solder”).

• Residues from rosin-based fluxes are the least corrosive and least conductive, making rosin based-fluxes most desirable for electrical soldering.

• Flux formulations can be made from non-rosin base materials with higher activity levels. The more active a flux is, the easier it removes oxidation -- but the more difficult it becomes to clean the residues after soldering.

• The residues from inorganic or water-based acid fluxes can be corrosive or cause shorts, which is why acid fluxes are NOT recommended for electrical soldering!

What Is Flux?

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Why Use Flux?

PURPOSE:

Flux ONLY removes the slight surface oxidation that occurswhile heating a metal during soldering.

Flux does not remove dirt, corrosion, finger oils,or other contamination.

These can only be removed by proper cleaning.

Two Good Rules of Thumb:

1) Adding more flux does not make a better connection,it just makes a bigger mess to clean up!

2) A little bit of flux goes a long way!

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Solder Wick

Solder Wick is a copper braid mesh materialthat comes in various sizes.

It is used to remove solder from connections thru wicking action.

Note: More on solder wick and how to use it later….

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II. TOOLS & EQUIPMENTII. TOOLS & EQUIPMENT

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Suggested Tools

Wire Strippers & Cutters

ReverseTweezers

Solder (2 sizes)

Iron Tips

Solder Wick

Bench Vise

Liquid Flux

Heat Gun

DremelTool

Solder Iron

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The Solder Iron

Hakko FX888 Solder Station EduTRAIN™

What Type of Solder IronIs Best?

The “Best” Solder Iron transfersHEAT

quickly and efficiently

#1 – A tip in good condition that “coats” well with solder

#2 - Interchangeable Tips

#3 - Adjustable Temperature Control

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III. GETTING READY TO SOLDERIII. GETTING READY TO SOLDER

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Before starting, Parts & Components should be Clean

CLEANING

REMEMBER --- Flux by itself does not clean dirty parts!

● Cleaning of contaminated/dirty parts may be accomplished with: - A brush with Isopropyl Alcohol, for light cleaning - Non-Abrasive cleaners (pencil eraser) - Abrasive cleaners (Dremel tool, sand paper, etc.)

● Heavily contaminated/oxidized parts may also be discarded! (I highly recommend only using new wire & parts.)

● If, during soldering, the solder balls up on your parts & wire, check how clean your parts & wire are!

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Wire SelectionStranded vs. Solid?

● Use stranded wire in locations where the wire must remain flexible

● Use solid wire for everything else!

--It’s just much easier to work with!

When should you use stranded wire and when should you use solid wire?

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What Type of ConnectionWill You Be Making?

Use a hook shape for:

Wire Splices & Terminals

WHY? Because they are--

SIMPLE TO MAKE & EASY TO USEEduTRAIN™

Pierced / Perforated Terminal

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Junction – Feeder Wires

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Flat Ribbon/Gull Wing (Surface Mount Lap Solder Joint)

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Prepare the Solder Iron

● Wet the sponge with lukewarm tap water. Keep it damp, not wet.

● Select a tip size and iron temperature based on the size of the work. (Suggestion: Start with a Medium size tip at ~700ºF setting.)

● Clean the tip between each connection by tinning it with a fresh coat of solder – apply a small amount of solder to the tip and wipe it off on the damp sponge.

Never clean the tip with an abrasive cleaner. If the tip does not tin well, get a new one!

● When finished, always apply a bead of solder to the tip (without wiping on the sponge) before placing it back in the holder.

● Turn off the iron when not in use (10 minutes or longer).

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Video #1: Using the Solder Iron

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Wire Preparation

Step 1: Strip the Wire

Video #2: Wire Stripping

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Step 2: Tinning

Always tin stranded wire:

• Aids the forming (turns the stranded wire into a solid wire)

• Improves solderability

Should You Tin Solid Wire?

• Normally, it is not necessary to tin solid wire …

… if the wire is clean & solderable to begin with.

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Video #3: Tinning

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Step 3: Form the Wire

When bending a wire, always form a curve

r ≥ 1d

90º

0º

Start ofBend

End ofBend

d

BendRadiusArea

Good Rule of Thumb:

The Bend Radius shouldbe > 1 diameter of the leadEduTRAIN™

Wire Forming - Incorrect

d

r = 0

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For most model RR connections,use a 180º Bend

0º

180º EduTRAIN™

IV. THE HAND SOLDERING PROCESSIV. THE HAND SOLDERING PROCESS

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Setting Up

2 Key Things to RememberWhen Setting Up to Solder:

1. There should be no movement between the parts you are soldering!

2. Always support the hand that’s holding the solder iron!

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Form The Heat Bridge

Iron Tip

Wire

Pad / Wire / Rail

Heat Transfer

Heat Transfer

IMPORTANT!

Once you have placed the iron tip in position,

Do Not Move It!

Step 1. Place the tip at the junction of both partsso that heat is transferred to

BOTH PARTS AT THE SAME TIME

No Need to apply pressure! The weight of the iron is sufficient EduTRAIN™

Step 2. Holding the solder wire in the other hand,get the solder flowing

Iron Tip

Wire

Pad / Wire / Rail

Heat Transfer

Heat Transfer

Solder Wire

Note: Dwell time mayneed to be as much as5 seconds, depending

on the size of the items.Be Patient!

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Step 3. Move the solder wire to the other side,

and let the solder flow back toward the heat source.

Iron Tip

Heat Transfer

Heat Transfer

Solder Wire

Solder Flow

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Step 4. When enough solder has filled in betweenthe connection elements,

remove the solder wire FIRST!

Iron Tip

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Step 5. Then remove the solder iron LAST!

Iron Tip

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Video #4: Splicing & Soldering

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How To Solder A Surface Mount “Lap” Solder Joint

A Special Case:

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If you use the traditional heat bridge method --you will need 3 hands!

Iron Tip

Solder WireWire, Resistor or LED Lead

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Step 1. Apply solder to the pad surface -–

Iron Tip

Solder Wire

Use the Reflow Method

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-- leaving a bead of solder on the pad.

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Step 2. Add a drop of liquid flux --

Flux

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Step 3. Holding the part/lead/wire with one hand and the iron with the other hand, lay the iron tip on top of the wire/lead.

Iron Tip

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Step 4. While holding the part/lead/ wire steady with one hand, remove the iron, and continue to hold the lead/wire steady until the solder cools.

Iron Tip

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The Result

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V. WHAT TO DO AFTER SOLDERINGV. WHAT TO DO AFTER SOLDERING

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Clean the Connection

• You should always clean the completed connection using isopropyl alcohol applied with a brush.

• Even “no-clean” fluxes leave a residue that may interfere with paint adhesion; “no-clean” just means that the residues will not cause corrosion or shorting.

• Cleaning is imperative if you use an acid-type flux for mechanical soldering. The residues can cause corrosion on your work. More aggressive cleaning methods may be necessary.

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The Most

IMPORTANT

Characteristic of a

GOOD

Solder Connection is

WETTING

Check Your Work –

What Should You Look For?

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≤ 30º

Wetting Is Judged by the Contact Angle

Wetting - Excellent

> 30º ≤ 60º

Wetting - Good

Wetting – Just Ok

> 60º ≤ 90º

Wetting – Poor

> 90º

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Check Your Work -- Example

Pierced Terminal (Both sides of the same connection are shown)

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The term “Cold Connection” is just another way of saying “Poor Wetting”

Poor wetting may be caused by either contamination or a lack of heat (i.e., cold)

What is a “Cold Connection”?

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VI. SOLDER REMOVAL/DESOLDERINGVI. SOLDER REMOVAL/DESOLDERING

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1. Solderwick method: - Apply a drop of liquid flux to the solderwick - Press the wick onto the connection with the iron tip - Let the heat draw as much solder away from the connection as possible - Remove the iron tip and the solderwick at the same time

2. Repeat Step 1 as necessary to remove as much solder as possible.

3. When it looks like all of the solder has been removed, you may need to touch the iron tip (without the wick) to the wire to allow the wire to pull away.

4. If parts are to be replaced, remove the remaining surface solder with the solderwick.

Using Solder Wick

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Video #5: Removing Solder

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VII. CONCLUSIONVII. CONCLUSION

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The 7 Sins of Hand Solderingfor Model Railroaders:

1. Using a solder iron with a bad tip; using the wrong tip size, temperature, or solder wire size for the work.

2. Not using clean (or new) parts. (Solderable parts solder best!)

3. Using too much flux. (Usually, the amount in the cored solder wire is all you need!)

4. Allowing movement between the parts during soldering.

5. Not supporting your hand holding the solder iron.

6. Not forming a correct heat bridge.

7. Moving the iron tip around during soldering. (Put it in one place and keep it there!)

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Soldering Resources

Clinic Presentation:

“The Art of Soldering”, http://www.rmrrc.net/clinics/36-digitrax-soldering-video/

Soldering Video:

“Basic Soldering”, http://www.digitrax.com/support/video-depot/dcc-basics/

Tools:

MCM Electronics – http://www.mcmelectronics.com Practical Tool - http://www.practicaltool.com

Micro Mark Tools – http://www.micromark.com

Electronic Parts & Wire:

All Electronics Corp. - http://www.allelectronics.com/

Mouser Electronics – http://www.mouser.com

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References:

1. NMRA Magazine, “Tool Car”, Feb 2014

2. Model Railroader, “Ready…Set…Solder!”, Feb 2007

3. Model Railroader, “The Lost Art of Soldering”, July 2003

4. NMRA Magazine, “The Pulse of DCC”, Feb 2015

5. Model Railroader, “Soldering With Mr. H” by Neil Besougloff, May 2013

6. Model Railroader, “The Art of Soldering” letter to the editor, by David Carlton, Aug 2013

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Remember:

There’s nothing difficult about soldering.It just takes a little practice.

So now, go home and practice!

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That’s All!That’s All!

Thank You For Attending!Thank You For Attending!

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