Intro. to Soldering Workshop

Through-hole Soldering

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Hosted By:

NEU Wireless

NU IEEE

Workshop Goals:

• Understand the basics of soldering tools, materials (such as solder and flux), and safety protocols.
• Practice soldering and desoldering techniques on through-hole components.
• Solder/Assemble a simple electronic circuit using through-hole components.

Workshop Structure:

Component Sequence

• Because our components are through-hole and we do not have soldering vises or helping hands, we start with the components ordered by vertical height.
• From low-profile resistors to taller components like capacitors and ICs.

Component Details

• Identity - We’ll explain what each component is.
• Polarization - Learn which components are electrically polarized.
• Self-Orientation - We’ll explain the proper orientation of the components themselves (it is not applicable for every component).
• Board Alignment - Learn how to align each piece on the board before soldering.

Soldering Techniques

• Concluding with soldering techniques (different for some components).

So, what are we making?

A “Traffic Light”, powered via USB Type-B 2.0:

Through-hole vs Surface-mount

Through-hole vs Surface-mount

From Hand-Soldering to Automation (Industrial Solutions):

Basic Soldering Tools

Iron & Station

Tweezers

Solder (lead-free)

What is soldering?

Soldering Iron + Solder = Soldering

• Essential for Electronics: Joins electronic components by melting a filler metal (solder) to form a durable bond.
• Solder: A low-melting alloy, often tin-lead (Leaded), or tin-silver-copper (lead-free), used to connect metal parts, like wires to a circuit board.
• Simple yet Skilled: Requires a soldering iron and steady hands, but is a fundamental skill for building and repairing electronics.

Safety - Don’t:

Source

Safety - Do:

The Ideal Solder Joint:

The Ideal Solder Joint:

Through-hole soldering technique - Creating a strong solder joint:

1. Heat Iron: Set to 700F/370C for 60/40 (lead-based, 60% tin, 40% lead) or 750F/400C for lead-free solder. We provide lead-free solder.
2. Prime Tip: Wipe the iron’s tip for better heat transfer (use the non-abrasive brass shavings)
3. Tin Tip: Add a bit of solder to the iron’s tip, then prime again.
4. Heat Joint: Iron touches both PCB pad + component lead to warm.
5. Solder: Apply to joint, not iron, then cool naturally.

Solder Flux is your friend

• Simply put, solder flux helps join metals; it makes soldering easier in both through-hole and SMT.
• There are several categories of solder flux (beyond the scope of this workshop). We supply you with liquid flux pens and a few Chipquik Tacky Flux’s (syringe-form).
• Oxidation is your enemy
• Forms on iron tip and prevents heat transfer/solder adhesion
• Forms on solder and prevents adhesion to surface/other solder
• Flux does a couple things:
• Prevents oxidation from forming on surface of solder
• Provides heat transfer between tip and solder

Liquid Flux Pen:

Tacky Flux:

Fixing Mistakes: Removing Solder

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Common Desoldering Tools

Available:

• Solder Wick: Ideal for precision removal of excess solder in through-hole and SMT.
• Manual Desoldering Pump (Solder Sucker): Great for quick removal in through-hole applications.

Not Available:

• Electric desoldering pump (desoldering gun): Perfect for rapid, continuous desoldering in high-volume through-hole jobs.

Fixing Mistakes: Using Solder Wick

Demo

See next slide for steps

Fixing Mistakes: Using Solder Wick

1. Place Wick Over Excess Solder
1. Position the desoldering braid on top of the unwanted solder.
2. Optional: Apply Flux to Enhance Wicking
• Flux can be used to improve the wick’s ability to absorb solder.
3. Optional: Pre-tin Iron Tip with Solder for Better Heat Transfer
• Adding a small amount of solder to the iron tip can help it heat the wick more efficiently.
4. Press Iron to Wick on Solder
• Gently press the heated iron to the wick where it covers the excess solder.
5. Wait for Solder to Absorb into Wick
• Hold in place until you see the solder melt and move into the braid.
6. Remove Wick with Iron Still Applied
• Carefully slide the wick and iron away together to leave behind a clean area.

Fixing Mistakes: Using a Manual Solder Sucker

Fixing Mistakes: Using a Manual Solder Sucker

Fixing Mistakes: Using a Manual Solder Sucker

1. Heat the Solder: Heat the solder joint with your soldering iron. Make sure the solder becomes fully melted.

2. Prepare the Desoldering Pump: While the solder is still liquid, remove the iron from the solder joint and immediately position the tip of the pre-primed desoldering pump (already cocked and ready to use) near the molten solder. The closer, the better, but avoid direct contact with the soldering iron tip.

3. Activate the Pump: Press the release button or trigger on the desoldering pump to create a vacuum. This action sucks the molten solder out of the joint and into the pump.

4. Remove Excess Solder: If any solder remains in the joint, repeat the process.

Now, let’s get started soldering our components.

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Remember, we will go component by component.

Resistors

What is it: A passive component that restricts current flow and helps control voltage levels in the circuit. You can tell what the resistance (in ohms) of a through-hole resistor is by its color code or multimeter

Polarized/Orientation Matter: No, resistors are not polarized, so orientation does not matter.

Orientation on component: No specific orientation needed for through-hole resistors.

Orientation on board: Insert the leads through the designated holes (refer to the designators on the board).

Soldering Technique: Bend the leads slightly on the other side of the board to keep the resistor in place. Flip the board and solder each lead, making sure the solder flows smoothly around the pad and lead for a reliable connection.

Resistors

Resistors

Through-hole

Resistor Color Code Calculator

{4,5,6}-Band

Timers (ICs - Integrated Circuits)

What is it: A 555 timer IC that generates timing signals in the circuit.

Polarized/Orientation Matter: Yes, orientation is crucial.

Orientation on component: Pin 1 is identified by a small circular divot or notch on the chip.

Orientation on board: Align Pin 1 with the board’s marking.

Soldering Technique: Place the IC onto the board, solder each pin, working from one side to the other to minimize heat buildup.

Timers (ICs - Integrated Circuits)

Information continued:

• These chips are what help determine how “long each light lasts”
• Can think of them as a form of automation

LEDs (Light Emitting Diode)

What is it: An LED that emits light when current flows through it.

Polarized/Orientation Matter: Yes, it is electrically polarized.

Orientation on component: The shorter lead indicates the negative end (cathode), or it may have a flat side.

Orientation on board:Align the negative end with the board’s marking for the cathode.

Soldering Technique: Insert leads through the board, ensure the cathode is in the correct hole, and solder each lead in place.

LEDs (Light Emitting Diode)

Capacitors (Electrolytic)

What is it: A component that stores electrical charge temporarily.

Polarized/Orientation Matter: Yes, electrolytic capacitors are polarized.

Orientation on component: The shorter lead is the negative side; the negative side may also have a strip with minus symbols.

Orientation on board: Place the negative lead in the marked hole.

Soldering Technique: Insert the leads, ensure correct polarity, and solder each lead securely to the pad.

Capacitors (Electrolytic)

USB Connectors

What is it: A USB Type-B 2.0 port/receptacle, used for power only in this case.

Polarized/Orientation Matter: Yes, the connector is physically polarized. It will only align one way.

Orientation on component: The connector aligns only one way onto the board.

Orientation on board: Match the connector’s shape with the board’s layout.

Soldering Technique: Align the connector on the board, ensure stability, and solder each leg carefully.

USB Type-B 2.0

Pin1

Build from shortest to tallest!

Check Your Work:

Troubleshooting Your Board: Tools Available

• Don’t be afraid to ask us
• Use a multimeter to check continuity or read resistor values
• Common mistakes:
• Double check you put the correct component in the correct designator
• Bridges/shorts: Double check all joints are are not bridged, resulting in short in the circuit

Other Awesome Resources:

• Adafruit Guide To Excellent Soldering (Web)
• Adafruit Guide To Excellent Soldering (PDF)
• Digikey - How to Solder
• NASA’s guide to soldering and workmanship standards
• Digikey - DIY Soldering Kits
• Cyber City Circuits - Learn to Solder
• Through-hole N-Band Resistor Color Code Calculator (Digikey)
• 555 Timer Calculator (Digikey)
• Decoding Resistors (Sparkfun)

Questions?

{elarbi.m, heaney.ma, aviedov.v}@northeastern.edu

References/Attributions

• https://www.pcbpower.us/blog/comparison-between-through-hole-assembly-surface-mount-assembly
• https://www.ifixit.com/products/precision-tweezers-set
• https://www.digikey.com/en/maker/projects/another-teaching-moment-through-hole-soldering-basics/be3bd0a005bd4df9927609d4ff4a7ab6
• https://learn.adafruit.com/adafruit-guide-excellent-soldering/common-problems
• https://en.wikipedia.org/wiki/Desoldering
• https://en.wikipedia.org/wiki/Flux_(metallurgy)
• https://www.chipquik.com/store/
• https://www.mouser.com/images/texasinstruments/hd/ITP_TI_PDIP-8_P_t.jpg
• https://www.adafruit.com/product/465
• Microsoft Excel Screenshots by Muhammad Elarbi, 2024, licensed under CC BY-SA 4.0.
• For certain images in this presentation, the original source is unknown. We acknowledge that these images may be subject to copyright, and we appreciate the work of the creators. If you are the creator of any of these images or know the original source, please contact us so that we can provide proper attribution or remove the image if necessary.