Pad Repair

With traces repaired, this chapter turns to the other copper feature a repair most often has to save: the pad — the copper landing a component leg, wire, or ball solders to. Pads fail in their own ways: lifted from the board by heat or prying, torn away entirely, or damaged at the ring around a plated hole. The chapter works through them in order of severity — re-adhering and reconnecting a pad that has lifted but survived, rebuilding a pad that has been destroyed, repairing the annular ring of a through-hole pad, and the exacting work of restoring a fine-pitch or BGA pad — then closes by verifying that a repaired pad is electrically sound and mechanically able to hold a component. By the end you can assess pad damage, choose the right repair for it, carry it out with a hot iron and the right materials, and prove the pad will hold.

• 6.1Lifted Pad RepairChapter 5 repaired the copper roads of a board; this chapter turns to the landings at their ends — the pads a component solders to — starting with the commonest pad fault, a pad that has lifted. A solder pad is the small area of copper a component lead, wire, or ball is soldered to, making both the electrical connection and the mechanical grip that holds the part. Like a trace, a pad is bonded to the board by an adhesive layer, and like a trace it can come loose: a lifted pad has peeled from the laminate beneath it, usually from too much soldering heat, a component pried off, or corrosion working underneath. This section saves the pad that has lifted but survived — still whole, just no longer stuck down. The key is re-adhesion: cleaning the pad and the board and bonding the pad back with a high-temperature adhesive that will survive soldering, so the pad holds while you resolder its component. Before that you assess — a pad still intact can be re-adhered, but one torn away, or sitting over cracked laminate showing pad cratering, may need rebuilding instead. And after, you reconnect the pad to its trace if that broke, resolder the component with as little heat as possible, and verify the pad holds and conducts. Learn what a pad is, why it lifts, and how to judge, re-adhere, reconnect, and verify one, and you can save a board a lifted pad would otherwise doom.IntermediateMedium Risk22 min read
• 6.2Rebuilding a Destroyed PadThe last section saved a pad that had only lifted; this one rebuilds a pad that is gone — torn away, its copper lost, or sitting over laminate too cratered to hold it. When a pad cannot be re-adhered because there is no sound pad left to stick down, the answer is a replacement pad: a fresh piece of copper, shaped to the pad's size and place, bonded to the board and connected to its trace, standing in for the copper that was destroyed. The new pad comes from one of two sources — copper foil, thin copper sheet you cut and shape yourself, or a pad-repair kit of pre-formed pads and lands sized to standard footprints. The work has a clear sequence: prepare the site by clearing the destroyed copper and any cratered laminate back to sound material and exposing the trace stub; cut and bond the new pad down with a heat-proof adhesive; connect it to its trace with solder or a short wire link; then resolder the component with the gentlest heat and verify the new pad holds and conducts. This section teaches when to rebuild, what to build from, and how to prepare, fit, connect, and verify a new pad — so a destroyed pad stops being the end of a board.IntermediateMedium Risk22 min read
• 6.3Annular Ring and Through-Hole Pad RepairThe pads repaired so far sat flat on the surface; this advanced section takes on the through-hole pad, which is really two connected features and so has two things that can fail. A through-hole pad has an annular ring — the ring of surface copper around a drilled hole, on one or both faces of the board — joined through the board by a barrel, the thin plated-copper wall lining the hole that carries the connection from side to side. A component lead passes through the hole and solders to the ring, and the barrel ties the two faces together. Either part can fail: the ring can tear or break, pulled off with a stubborn component, and is repaired much as any pad by rebuilding it from copper and reconnecting it to its trace; the barrel is harder — its plating can crack or be destroyed when a seized lead is drilled out, breaking the connection through the board. When the barrel is gone, the through-connection is restored mechanically with an eyelet, a small hollow rivet fitted into the hole and set by swaging so its flared ends grip the ring on each side, or, where it suffices, with a wire passed through the hole and soldered to both sides. Deep barrel re-plating belongs to via repair in the next chapter. This section walks the anatomy, the failure modes, rebuilding a ring, restoring the through-connection by eyelet or wire, and fitting the lead and verifying both sides — so the most structured pad on the board becomes repairable.AdvancedMedium Risk24 min read
• 6.4SMD and Fine-Pitch Pad RepairThe pads so far have been ones you can see and reach; this section takes on the smallest and most demanding — the fine-pitch surface-mount pads, and the hidden pads of a ball grid array, where everything that makes pad repair hard is multiplied. A fine-pitch pad is one of a row set very close together, its pitch (the center-to-center spacing) perhaps half a millimetre or less, so the pads are tiny, thin, close-packed, and easily bridged. A ball grid array is harder still: its connections are an array of solder balls on the underside of the package, landing on a grid of pads hidden beneath it, so a damaged pad may not even be reachable without removing the chip. Rebuilding a fine-pitch pad uses the same idea as any pad — a new land from a kit or cut copper, bonded and reconnected — but at a size that demands a microscope and a steady hand, and refitting a fine-pitch or BGA part needs hot-air rework, reflowing solder paste with a controlled stream of hot air rather than an iron. Above all this section teaches a limit: much BGA and multi-pad fine-pitch damage — especially hidden pads under a fitted package — is beyond hand repair and belongs to professional reball and rework. Learn what makes these pads hard, how to assess and rebuild a fine-pitch pad, how to rework with hot air, when to stop, and how to verify under magnification — and you meet the hardest pad repair with judgement intact.AdvancedHigh Risk24 min read
• 6.5Pad Repair VerificationThis chapter has repaired every kind of pad — lifted, destroyed, through-hole, and fine-pitch — and each ended by pointing here, to the check that proves a pad repair sound. A pad is not a trace: it does two jobs at once, carrying a connection and holding a component, so verifying a pad repair means proving both, that it conducts and that it grips. The electrical check is familiar from trace verification — continuity and resistance from the component through the pad to its trace, near a known-good value, with no short to a neighbour. The mechanical check is what a pad adds: a repaired pad must physically hold its part, so you confirm its bond and its joint integrity by reading the solder fillet and by a pull test, a gentle controlled tug on the component that a sound pad survives and a weak one gives up under. Beyond the bench a pad repair is proven in service, the part staying put and conducting under power, load, and time. And it ends in a decision: a pad that passes both the electrical and the mechanical check is done; one that fails either is redone or, if it cannot be made sound, referred. This section closes the pad-repair chapter by teaching how to verify a pad both ways, test it in service, and judge and record it — so you can prove your work on every pad you repair.IntermediateMedium Risk21 min read
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