Magnet Wire Repair

Section Overview

Section 5.3 bridged a short break with solder, but solder has no strength across a long gap; where a break is too long to bridge — or where corrosion or damage means the connection must be rerouted — the repair is a wire link (§5.3). A short length of fine wire, soldered to sound copper at each end, carries the connection across the gap the way the original trace did, and for the finest work that wire is usually magnet wire — solid copper under a thin baked-on enamel — or a fine insulated hook-up or Kynar wire (jumper wire). The method adds a few demands over a plain solder joint. The first is choosing the right wire gauge — the wire must carry the trace's current, so you match its thickness, measured in AWG where a higher number is thinner, to what the trace needs, a heavier gauge for a supply trace and a fine one for a signal (§2.4). The second is preparing the wire: magnet wire's enamel is an insulator, so it must be stripped and the end tinned before it will take solder. The third is securing the run: a wire soldered at both ends but left loose will flex and eventually crack its joints, so you tack it flat to the board to give it strain relief against that movement. And the fourth is insulation: the run must not short to whatever it crosses, so a bare stretch is covered with sleeving — thin insulating tubing — or resealed with mask. Done well, a wire link is a strong, low-resistance, and versatile repair that can bridge almost any length and reroute a connection around damage no in-place repair could reach. Learn when a wire link fits, how to size, strip, and tin the wire, how to route, tack, and solder it, and how to insulate and verify it — and you can repair a break of almost any length.

Why This Matters

A wire link is the most versatile trace repair there is — it can cross any gap and reroute around damage — but that reach comes with the responsibility to size it, secure it, and insulate it, or it fails in ways a short solder joint never would. This matters because solder cannot span a long gap: once a break is longer than a millimetre or two, an unsupported solder bead is weak and unreliable, so a wire is the only sound way to carry the connection across (§5.3). This matters because the wire must carry the current: a wire too thin for a supply trace will heat and drop voltage, so matching the wire's gauge to the trace's need is what keeps the repair as good as the original (§2.4). It matters because an unsecured wire fails at its joints: a link left loose to flex and be tugged will fatigue and crack where it is soldered, so tacking it down for strain relief is what makes the repair last. It matters because a bare wire shorts: a link that crosses other traces or pads will short to them unless its bare stretches are insulated, turning a repair into a new fault. And it matters because reach enables rerouting: when corrosion or damage has destroyed a stretch of trace, a wire can carry the connection around the ruined area entirely, saving a board that no in-place repair could (§5.1). Learn to size, route, secure, and insulate a wire link, and you gain the repair that can fix what the others cannot reach.

Required Prerequisites

• Solder Repair — Section 5.3 taught the soldering, heat control, and joint-reading a wire link depends on; a wire link is two solder joints with a wire between them.
• Identifying Damaged Traces — Section 5.1 taught you to find, confirm, and scope a break, including judging the gap length that tells you a wire link is needed. Magnet wire and jumper wire, and how a trace's width sets its current (§2.4), also feed this section. This is a hands-on hot-work repair section — read the Safety Notes before starting.

Recommended Consumables

• Magnet wire in a few sizes, around 30 to 40 AWG, and some fine insulated hook-up or Kynar wire — the conductor that carries the repair across the gap
• Flux and fine solder — to tin the wire and copper and make the two end joints (§5.3)
• Isopropyl alcohol and lint-free swabs — to clean the break and remove flux residue after
• A small tube of adhesive, or Kapton tape — to tack the wire flat to the board for strain relief
• Sleeving, heat-shrink, or a solder mask pen — to insulate any bare stretch of the wire
• Scrap boards with longer trace breaks — to practise on; do NOT practise on any device you intend to use, sell, or return

Recommended Practice Hardware

• A temperature-controlled soldering iron with a fine tip, around 350 °C — to make the two end joints quickly and cleanly (§5.3)
• Fine tweezers and a heat-shunt clip — to place the fine wire and to draw heat from a nearby part (§4.3)
• A way to strip enamel — a sharp blade, fine abrasive, or the iron and flux — to bare the magnet wire's ends for soldering
• A magnifier or loupe and a bright light — to route the fine wire and inspect its joints
• A multimeter with a low-ohms range — to verify the link by resistance, not just a continuity beep (§5.1)
• Good ventilation or a fume extractor — to keep flux and enamel-burn fumes out of your breathing air

Real-World Applications

A wire link is the repair that turns up wherever a break is too long or too awkward for an in-place fix, and it rescues boards the other methods cannot. A technician facing a trace destroyed over a centimetre by corrosion reroutes the connection on a magnet wire soldered to sound copper beyond the damage (§5.1). Someone repairing a board where a wide track has been gouged away chooses a heavier wire gauge so the link carries the same current the track did (§2.4). A repairer bridging a break that would leave a long, fragile solder bead runs a fine wire instead for a joint that is strong at both ends and supported between them (§5.3). A technician linking two points across a crowded board sleeves the wire so it cannot short to the traces it crosses (sleeving). And a repairer whose earlier loose jumper cracked its joint now tacks every link flat to the board so it cannot flex (strain relief). The failures this skill prevents: a solder bead too long to hold, a link too thin for the current, a bare wire shorting to its neighbours, and a joint cracked by an unsecured, flexing wire.

Common Challenges

• Choosing too thin a wire. A fine wire cannot carry a supply trace's current and will heat or drop voltage — match the wire gauge to the trace's need (§2.4).
• Leaving the wire loose. An unsecured link flexes and cracks its joints — tack the run flat to the board for strain relief.
• A bare wire shorting. A stripped or uninsulated stretch shorts to what it crosses — insulate it with sleeving or reseal it before trusting the repair.

Safety Notes

Risk Level: Medium. A wire link is soldering work, so the hot-iron hazards of the last section all apply — with the small addition of the fumes from stripping enamel.

Professional Tips Before Starting

• Size the wire first. Decide the gauge from the trace's current before anything else — a link too thin for the job is a repair that fails under load (§2.4).
• Tack before the second joint. Solder one end, route and tack the wire flat, then solder the other — a secured wire will not pull its own joints as you work.
• Insulate as you finish. Sleeve or reseal any bare stretch before you call the repair done — a bare link is a short waiting to happen (sleeving).

Repairing a Trace with a Wire Link

Recap and Frame

The last section bridged a short break with solder, and this one carries a break of any length on a wire — so the frame to hold is that a wire link is the most versatile of the trace repairs, and the one to reach for when a gap is too long or a route must change (§5.3). The idea is simple: rather than fill the gap, you span it with a conductor — a short length of wire soldered to sound copper at each end — that carries the connection across, exactly as the original trace did. This does two things solder alone cannot. It bridges a long gap: a wire is strong along its length, so it spans a centimetre as easily as a millimetre, where an unsupported solder bead would sag and crack (§5.1). And it reroutes: because the wire can take any path between its two endpoints, it can carry a connection around a stretch of trace that corrosion or damage has destroyed, reaching sound copper well beyond the ruin. The cost of that versatility is a few extra steps — sizing the wire to the current, stripping and tinning it, securing it against flexing, and insulating it against shorts — and the rest of this section walks them in order: choose the wire, prepare it and the break, route, tack, and solder the link, then insulate and verify it. Hold the frame — solder for a short gap, ink for a light low-current break, a wire link for a long gap or a reroute — and you will know when the extra steps are worth taking (§5.2; §5.3).

When a Wire Link Suits a Break

Choosing a wire link over the other methods comes down to gap length, current, and whether the connection must be rerouted. Its defining strength is reach: a wire has strength along its length, so it can bridge a gap of any size — the moment a break is too long for solder to span reliably, a millimetre or two, a wire link is the answer (§5.3). Its second strength is rerouting: the wire can follow any path between the two points it joins, so where a stretch of trace is destroyed — eaten by corrosion, gouged away, or burnt — a link can carry the connection around the damage entirely, soldering to sound copper on each side of the ruin rather than trying to rebuild what is gone (§5.1). The key choice within the method is the wire gauge: the link must carry the same current the trace did, so you size the wire to the trace — a heavier gauge for a supply or power trace, a fine 30 to 40 AWG magnet wire for a low-current signal — because a wire too thin will heat and drop voltage under load (§2.4). A wire link does have limits. It cannot repair an inner-layer break in place any more than solder can, though it can bypass one across the surface (§2.5; §5.5). And for a very light, low-current break where heat is unwelcome, conductive ink may still be simpler (§5.2). But for the broad middle — any break too long for solder, or any connection that must be rerouted — the wire link is the method. Weigh length, current, and route, and the wire link's place becomes clear.

Preparing the Wire and the Break

A wire link is only as good as its two joints, so preparation means readying both the wire and the copper to solder cleanly. Start with the wire. Cut a length a little longer than the run you need, and strip its ends: magnet wire is coated in a thin baked-on enamel that is an electrical insulator, so the last few millimetres of each end must be bared before the wire will take solder, either by scraping the enamel off with a blade or fine abrasive or by burning it off with the iron and a little flux. Then tin each bared end: a light coat of solder confirms the enamel is fully off and readies the end to join. If the wire is insulated hook-up or Kynar rather than magnet wire, strip the plastic insulation back cleanly without nicking the copper, and tin the exposed end. Now prepare the break exactly as for a solder repair: clean it with alcohol, abrade back to bright copper on both sides — or to sound copper well beyond a corroded stretch if you are rerouting — flux it, and tin each landing point where the wire will attach (§5.3; §5.1). Tinning both the wire and the copper is what lets the two flow together into a clean joint at a brief touch of the iron. If either will not tin, it is not clean: re-strip the wire or re-expose the copper before going on. With the wire tinned at both ends and the copper tinned at both landings, the link is ready to fit. Prepare both halves of every joint, and the soldering itself is quick and sure.

Routing, Tacking, and Soldering the Link

Fitting the link is a sequence — solder one end, route and secure the wire, then solder the other — that keeps the wire under control and its joints unstrained. Begin by soldering one tinned end to its tinned landing with a brief, hot touch, letting the two flow into a shiny joint and holding still while it cools (§5.3). Then route the wire. Lay it flat along a sensible path to the other landing — the shortest sensible route that avoids crossing anything it could short to — and press it down against the board. Now tack it down for strain relief: a small dab of adhesive, or a tab of Kapton tape, at one or two points along the run holds the wire flat so it cannot flex, lift, or be tugged, which is what would otherwise fatigue and crack its end joints over time. With the wire secured, solder the second end to its landing the same way, keeping the touch brief so the heat does not lift the pad or cook a nearby part, and heat-sinking a delicate neighbour if one is close (§4.3). Read both joints: each should be shiny and smoothly wetted, not dull or grainy, and mechanically solid. Keep the run neat and flat: a wire standing proud of the board is easy to snag and hard to insulate, while a wire tacked flat is protected and tidy. Soldered at both ends and secured between them, the link now carries the connection — but it is not finished until it is insulated. Fit it in that order and the wire never pulls against a joint that is still cooling.

Insulating and Protecting the Link

A finished wire link must be insulated so it cannot short, and protected so it will last — the step that turns a bare conductor into a safe, permanent repair. Consider what is bare. Magnet wire's own enamel insulates the length of the run, but the stripped, tinned ends and joints are bare metal, and a plain hook-up wire may have bare stretches too, any of which can short to a trace, pad, or component the wire passes or touches. Insulate those bare stretches. Where a bare length runs near other conductors, cover it with sleeving — thin insulating tubing slipped over the wire, or heat-shrink shrunk down onto it — so it cannot touch what it crosses. Over a bare joint or a short bare stretch, a coat from a solder mask pen or a dab of insulating lacquer does the same (§5.3). Check the whole run for shorts: look, and measure, to confirm the link touches only its two intended landings and nothing else — a wire link that shorts to a neighbour has replaced one fault with another. Then protect the repair: the tack points give it mechanical security, and a final bead of adhesive over a vulnerable joint or a length of exposed wire guards it against handling and flexing. Clean off flux residue with alcohol so it cannot trap moisture or hide a fault. Insulated against shorts and secured against movement, the link is now a finished repair. Insulate every bare stretch and confirm no stray short, and the versatility of the wire link comes with none of its risks.

Verifying the Repair

A wire link is not finished until it is proven, and verifying one means confirming both that it connects and that it connects only where it should. Test electrically first: a continuity beep should now sound across the once-broken trace, and a resistance reading on a low-ohms range should be near that of a healthy copper trace — a wire link, unlike a conductive-ink track, adds almost no resistance, so a high or drifting reading points to a cold joint at one end that needs reflowing (§5.1; §5.3). Inspect both joints under magnification: each should be shiny and smoothly wetted, not dull or grainy, and the wire should flow cleanly into each landing. Check the whole run for shorts: look along its length, and measure, to confirm the link touches only its two intended points and nothing it crosses — a bare stretch shorting to a neighbour is the wire link's own failure mode, so this check is not optional. Test it mechanically: a gentle nudge on the wire should move neither a joint nor the tacked run, because a joint that shifts was never soundly made, or the wire was never secured. Only when the link reads low resistance end to end, shorts to nothing, and holds firm is the repair complete — the standard of proof every trace repair in this chapter is held to (§5.1).

Common Mistakes

• Under-sizing the wire. A wire too thin for the trace's current heats and drops voltage — match the wire gauge to the load (§2.4).
• Not stripping the enamel fully. Magnet wire will not solder through its enamel, giving a false or open joint — bare and tin each end until it takes solder cleanly.
• Leaving the run loose. An unsecured wire flexes and cracks its joints — tack it flat for strain relief before soldering the second end.
• Skipping insulation. A bare stretch shorts to what it crosses — sleeve or reseal every bare length (sleeving).
• A dull joint at the end. A cold joint at either landing is weak and high-resistance — tin both halves and let the solder flow shiny (§5.3).

Troubleshooting Guidance

Wire-link problems come down to a joint that will not take, a link that shorts, or one that fails under load. If the wire will not solder: its enamel is not fully stripped — re-bare and tin the end (§5.3). If a joint is dull or the repair reads open: it is a cold or incomplete joint — reflow it and re-measure (§5.1). If the repair reads high resistance or drops voltage under load: the wire is too thin for the current — replace it with a heavier wire gauge (§2.4). If a neighbouring net is now shorted: a bare stretch is touching it — insulate the run with sleeving and recheck. If the joint cracks or the link goes intermittent later: the wire was not secured and flexed — tack it flat for strain relief and reflow the joint. If a pad lifts while soldering: you are overheating — work faster and hotter, and heat-sink the area (§4.3). If the break is on an inner layer: a surface wire link can bypass it, but it cannot be repaired in place (§2.5; §5.5). If you are unsure the link is sound: measure its resistance and check for shorts rather than trusting the beep. The throughline: size, strip, and tin the wire, solder shiny joints, secure the run, insulate every bare stretch, and verify by resistance.

Verification & Testing Methods

Confirm the repair by measurement and inspection before trusting it:

• [ ] I chose a wire gauge that can carry the trace's current, sizing it to the load (§2.4).
• [ ] I stripped and tinned the wire's ends and tinned the copper, then soldered shiny joints at both landings (§5.3).
• [ ] I routed the wire flat and tacked it down for strain relief so it cannot flex its joints.
• [ ] I insulated every bare stretch with sleeving or fresh mask and confirmed the link shorts to nothing it crosses.
• [ ] I verified the repair with a continuity beep and a resistance reading near that of a healthy copper trace (§5.1).

Then try the practice exercises below — hands-on repair practice on scrap boards; scenarios differ from the quiz.

Practice Exercises

1. Size, strip, and tin (7 minutes, hands-on). For a break on a scrap board, choose a wire gauge for its likely current, cut a length, strip the enamel from both ends, and tin them (§2.4).
2. Solder and route (7 minutes, hands-on). Tin the two landings, solder one end of the wire, route it flat to the other landing, and tack it down before soldering the second end (§5.3).
3. Insulate and check for shorts (5 minutes, hands-on). Sleeve or reseal any bare stretch, then confirm with the meter that the link connects only its two intended points and shorts to nothing else.
4. Verify (6 minutes, hands-on). Measure the link's continuity and resistance against a healthy trace, inspect both joints for shine, and give the wire a gentle nudge to confirm it is secure (§5.1).

These core ideas — when a wire link fits, sizing the wire, stripping and tinning, routing, tacking, and soldering, and insulating and verifying — are tested in the Chapter Quiz at the end of this chapter, where a score of 80% is required to continue.

Key Takeaways

• A wire link — a length of fine wire, often magnet wire, soldered to sound copper at each end — carries a connection across a break of any length and can reroute it around damage no in-place repair could reach (§5.3; §5.1).
• Match the wire gauge to the trace's current: a heavier gauge for a supply trace, a fine 30 to 40 AWG magnet wire for a signal, because a wire too thin heats and drops voltage (§2.4).
• Prepare both halves of every joint: strip the enamel and tin the wire's ends, and clean, expose, and tin the copper, because bare enamel or dirty copper will not take solder.
• Secure the run for strain relief by tacking the wire flat to the board so it cannot flex, lift, or be tugged, which would otherwise crack its end joints over time.
• Insulate every bare stretch with sleeving or fresh mask and confirm the link shorts to nothing it crosses, then verify by a resistance reading near copper's (§5.1).

Skills Learned

• You can now judge when a break needs a wire link rather than solder or ink.
• You can now choose a wire gauge suited to the trace's current.
• You can now strip, tin, and prepare a magnet wire and the break.
• You can now route, tack, and solder a wire link with strain relief.
• You can now insulate, verify, and protect a wire-link repair.

Glossary Additions

• wire gauge — the thickness of a wire, most often stated in American Wire Gauge (AWG), a scale in which a higher number means a thinner wire. A wire's gauge sets how much current it can carry without overheating, so in repair you choose a gauge to match the current the trace must carry: a heavier (lower-number) gauge for a supply or power trace, and a fine one — such as 30 to 40 AWG magnet wire — for a low-current signal. A wire link made with too thin a gauge will heat and drop voltage under load, so sizing the wire is the first decision of a wire-link repair.
• strain relief — any means of securing a wire so that flexing, pulling, or vibration acting on the wire is not transmitted to its soldered joints, which would otherwise fatigue and crack. In a wire-link trace repair, strain relief is provided by tacking the wire flat to the board with a dab of adhesive or a tab of tape at one or more points along its run, so the wire cannot lift, flex, or be tugged at its ends. Providing strain relief is what makes a wire link last, because an unsecured link almost always fails at a joint rather than along the wire.
• sleeving — thin insulating tubing slipped over a bare wire to insulate it from the conductors it passes or crosses, and to protect it; heat-shrink tubing, which shrinks tightly onto the wire when warmed, is a common form. In a wire-link repair, sleeving covers any bare stretch of the link so it cannot short to a trace, pad, or component, turning an exposed conductor into an insulated one. Where sleeving will not fit, a coat of solder mask or insulating lacquer serves the same purpose over a short bare length.

Suggested Next Sections

Must read next:

• Surface vs Internal Trace Repair — Section 5.5 draws together the methods so far and confronts the divide that has run through the chapter: a surface trace you can repair directly, and an inner-layer trace you can only bypass — when each applies, and how to bypass a buried break on the surface.

Recommended:

• Solder Repair — the soldering, heat control, and joint-reading that a wire link's two joints depend on.
• Identifying Damaged Traces — scoping the break and its gap length, which tells you when a wire link is needed.