# Chip Change (DD-626) > Replacing a chip on a circuit board is called rework, and the industry's guide to it is the IPC-7711/7721 standard. With a surface-mount chip, every joint has to melt at the same time, or the part can't come off cleanly. A hot-air rework station does this by blowing controlled hot air through a nozzle sized to the part. Many setups also warm the whole board from below with a preheater. Flux goes on first to help the solder flow. Once all the joints are molten, the chip is lifted with tweezers or a vacuum pickup. The bare pads are then cleaned with fresh flux and solder wick, braided copper that soaks up old solder. Too much heat or scrubbing can tear a pad off the board. The new part is lined up, tacked in place and reflowed, then checked for bridges (solder shorting two leads), cold joints and lifted pads. Many chips on modern motherboards are ball grid arrays (BGAs). They have no pins: rows of solder balls sit hidden underneath, so they are usually reworked with special equipment, and their joints can't be checked by eye. - Department: Tech - First published: 2025-07-29 - Last updated: 2025-07-29 - Permalink: https://detailenjoyer.com/case/chip-change/ - Author: Marcus Easterling (DetailEnjoyer), The Detail Department ## Quick facts - **DD-626-F01**: Replacing a chip on a board is called rework. _(Write-up · Exhibit A (It's called rework))_ - **DD-626-F02**: Ball grid array chips have no pins, only hidden solder balls. _(Write-up · Exhibit E (Hidden joints))_ ## Write-up Swapping a chip by hand. Hot air melts the solder, then flux and wick clean the pads. 1. **It's called rework**: Replacing parts on finished boards is called rework, and IPC-7711/7721 is the industry standard for it. 2. **All joints at once**: Hot air melts every joint together, so the chip lifts off cleanly. A preheater often warms the board from below. 3. **Pad prep**: Flux and solder wick clear the old solder. Too much heat or scrubbing can lift a pad. 4. **Back on**: The new part is aligned, tacked, reflowed, then inspected for bridges and cold joints. 5. **Hidden joints**: Ball grid array chips have solder balls underneath instead of pins, so their joints can't be checked by eye. ## Related case files - [Shrinking Circuits (DD-018)](https://detailenjoyer.com/case/shrinking-circuits/): How the chips got so small - [Print Precision (DD-005)](https://detailenjoyer.com/case/print-precision/): Another precision electronics process - [Ada All-Time (DD-095)](https://detailenjoyer.com/case/ada-all-time/): I linked where computing hardware ended up - [Quartz Crystals (DD-168)](https://detailenjoyer.com/case/quartz-crystals/): I linked more about electronics ## Reel vs. record - **Note**: 'Each pin': many motherboard chips are ball grid arrays (BGAs) with solder balls hidden underneath, not pins. Their joints can't be inspected by eye. - **Note**: 'Heat gun': a general-purpose heat gun is too crude for most boards. Rework stations use a controlled hot-air nozzle, often with a preheater warming the board from below. - **Order**: flux goes on before heating, to help the old solder melt and flow. It isn't only used for cleanup. - **Missing risk**: too much heat or scrubbing with the wick can tear pads off the board. Those pads then need repair. - **Missing**: this work has an industry standard, IPC-7711/7721, which covers hot-air reflow, pad prep and fixing bridges and cold joints. ## Video: Chip Change: Swapping a Chip by Hand - Duration: 33.0 s · Published: 2025-07-29 - File: https://detailenjoyer.com/assets/videos/DMtu1Alxg4L.mp4 ### Transcript DID YOU KNOW? Chips on a motherboard can be replaced using soldering in a meticulous process that requires precision, proper tools, and a steady hand. It starts by identifying the faulty chip and carefully cleaning the area around it. Using a heat gun or rework station, controlled heat is applied to melt the solder holding the chip in place, allowing it to be gently removed with tweezers. The exposed pads are then cleaned using flux and a solder wick to remove old solder. Once the new chip is correctly aligned on the board, heat is reapplied to secure it, ensuring each pin is properly soldered without any accidental bridges or cold joints. NOW YOU KNOW! ## Questions & answers **Q: What is replacing a chip on a finished board called?** A: It's called rework. _(Source: Write-up · Exhibit A (It's called rework) · IPC-7711/7721C (2017): Rework, Modification and Repair of Electronic Assemblies (ANSI webstore); IPC-7711C/7721C table of contents)_ **Q: Why use hot air on a surface-mount chip?** A: Every joint has to melt together. _(Source: Write-up · Exhibit B (All joints at once) · OKI: Surface Mount Rework Techniques (SMTnet library); Quecoo: What is a soldering rework station? Soldering iron, hot air and preheater systems explained)_ **Q: What does solder wick do?** A: The copper braid absorbs molten solder. _(Source: Write-up · Exhibit C (Pad prep) · OKI: Surface Mount Rework Techniques (SMTnet library))_ **Q: What is a solder bridge?** A: Unwanted solder joining neighboring leads. _(Source: Write-up · Exhibit D (Back on) · OKI: Surface Mount Rework Techniques (SMTnet library); IPC-7711C/7721C table of contents)_ **Q: What sits under a BGA chip instead of pins?** A: A grid of solder balls. _(Source: Write-up · Exhibit E (Hidden joints) · OKI: Surface Mount Rework Techniques (SMTnet library))_ ## Sources - [OKI: Surface Mount Rework Techniques (SMTnet library)](https://smtnet.com/library/files/upload/OKI-SMT-Techniques.pdf) - [IPC-7711/7721C (2017): Rework, Modification and Repair of Electronic Assemblies (ANSI webstore)](https://webstore.ansi.org/standards/ipc/ipc77117721c2017) - [IPC-7711C/7721C table of contents](https://www.electronics.org/TOC/IPC-TOC-7711-21C.pdf) - [Quecoo: What is a soldering rework station? Soldering iron, hot air and preheater systems explained](https://www.quecoo.com/blogs/blog/what-is-a-soldering-rework-station-soldering-iron-hot-air-and-preheater-systems-explained) ## Cite this case file Easterling, Marcus. "Chip Change." The Detail Department (DetailEnjoyer), case file DD-626, last updated Jul 29, 2025. https://detailenjoyer.com/case/chip-change/