SMD hand soldering looks impossible from outside and is merely disciplined in practice. Flux, a fine tip, magnification and two techniques drag-soldering pins, and hot-air for the rest.
At a glance: 7 minute guide · part 6 of 10 in the tools and equipment complete guide track · includes a worked example and a quick-reference table.
Two-pin passives
Tin one pad, place the part with tweezers while reflowing that pad, then solder the second end. Surface tension self-centres 0603-and-up parts beautifully. Inspect under magnification: the joint either looks like a tiny tent or it does not.
| Package | Method | Difficulty |
|---|---|---|
| 0805/0603 passives | Iron, two-pad | Easy |
| SOT-23/SOIC | Iron, pin by pin | Easy |
| TQFP 0.5 mm | Drag + flux | Moderate |
| QFN/DFN | Hot air | Moderate |
| BGA | Stencil + oven/reflow | Not hand work |
IC pins and drag soldering
Flood pins with flux, tack two corner pins, then drag a lightly-tinned chisel tip across the pin row surface tension deposits perfect fillets and bridges self-clear into the flux. Wick rescues the rare stubborn bridge from the opposite direction.
Hot air and realistic limits
Hot air reflows QFNs and connectors a iron cannot reach. Preheat gently, flow with circular motion, watch the part settle. With practice, 0. 5 mm pitch is routine; 0. 4 mm demands better tools and honestly a stencil.
How to apply this in your build
Work through the sequence below each step assumes the previous one passed. For numbers that need calculating, the linked tools at the end of this guide do the arithmetic instantly.
- Flood the work area with flux before touching it
- Tack one end/corner and verify placement under magnification
- Drag-solder pin rows, then wick any bridge
- Clean and inspect flux hides sins
Worked example
A first TQFP-32 drag-soldered with generous flux needed one wick pass on two pins and measured perfect continuity the intimidating package took under four minutes. Run the numbers yourself with the related calculator and the result should agree to within rounding.
Practical note from the bench. Flux is the entire secret: our SMD sessions use more flux than solder, by volume and by philosophy.
Pitfalls that cost real hardware
- Dry joints no flux, no flow, bridges everywhere
- Pressing parts with the iron instead of letting surface tension place them
- Attempting BGA hand rework and discovering physics
Key takeaways
- Two-pin passives the foundation of this guide; revisit it if any measurement here surprises you.
- IC pins and drag soldering the foundation of this guide; revisit it if any measurement here surprises you.
- Hot air and realistic limits the foundation of this guide; revisit it if any measurement here surprises you.
Prerequisites and preparation
Before starting: flood the work area with flux before touching it and tack one end/corner and verify placement under magnification. Keep a calculator to hand every number in the worked example is reproducible. Total time including the bench steps: about 6–7 minutes.
Who benefits most
Hobbyists meeting this topic for the first time, students who want the version with real numbers instead of abstract symbols. Returning engineers refreshing a corner of the craft. The mistake list alone justifies the visit every entry in it was learned the expensive way.
Quick reference card
| Aspect | Where to find it in this guide |
|---|---|
| Core theory | Two-pin passives |
| Application steps | How to apply this in your build |
| Worked numbers | Worked example |
| Failure modes | Pitfalls that cost real hardware |
How this fits the tools and equipment complete guide track
This guide is one stop in the structured learning path. Start from the tools and equipment complete guide complete guide for the full map, or continue with temperature basics and hot air rework.
Frequently asked questions
What tip for SMD? A small chisel or hoof (1–2 mm) fine enough for pins, broad enough to transfer heat. Conical needles starve joints.
Do I need a microscope? Magnification is the difference between hoping and seeing; a £20 loupe already transforms results.
Where do I go next? Back to the tools and equipment complete guide complete guide it indexes every guide in this track and updates as new ones are published.
Continue this track
- Building a foundation? The tools & equipment complete guide maps every step in order.
- Next: Using an LCR Meter: Measuring L, C and R Properly
- Next: Soldering Iron Temperature: The Numbers That Work
- Next: Logic Analyzers: Watching Digital Buses Talk
- Work the numbers: frequency converter · trace width tool
Continue the learning path
- The complete tools & equipment guide: Tools & Equipment complete guide
- Read next: how to use a multimeter: every mode that matters
- Also in this track: oscilloscope triggering: the skill that makes waveforms stand still
- Continue with: probe compensation: the one-minute scope calibration
- Calculate as you go: frequency and wavelength tool · trace width calculator · resistor decoder
- Bookmark this page against the day a measurement surprises you. Most readers return to the table and the mistake list first, and that is the correct order.
Measurement discipline
Keep a lab notebook entry for every build in this track. The measured values, the deviations from the guide and the reason for each. Six months from now, those notes are worth more than any tutorial. They describe your bench and your components rather than a general case.
When a result here disagrees with your expectation, write down both numbers before changing anything. The gap between predicted and measured is where the real engineering lives. It is usually a tolerance, a parasitic or an assumption that was never checked.
Formulas and checks from this guide
Verification checklist for this track: compensate probes before trusting amplitudes, verify meter fuses before current work. Keep one known-good reference to sanity-check instruments. Calibration you can demonstrate beats calibration you assume.
Bookmark this page against your next build in the track. The checklist above is the same one used across 12 guides in this series.
Hard-won notes
After every move between scopes, and monthly as ritual. It costs one minute.
Warm-up drift is real in both. Swap in a known-good reference to decide which side drifts.
Last updated 23 August 2026