Basics Of PCB Rework and Repair
Sep 2nd 2022
Soldering operations rarely result in 100% error-free assemblies. Occasionally, not even the best parts will hold up. This is why it's crucial for individuals who create, maintain, or repair PCBs to be familiar with proper circuit board rework procedures and safety measures.
How should circuit boards (PCBs) be handled to avoid injury?
Handling PCBs requires caution to avoid causing more harm than good. Here are a few points to consider:
● Use protective eyewear
It is important to always wear protective eyewear when working on a PCB since solder flecks and stray leads from lead trimming might cause damage.
● Turn off and discharge your gadgets
If you're working on an electrical gadget, unplug it and let the battery die completely to eliminate the risk of a short circuit and an electric shock. It is important to make sure that all capacitors and voltage regulators are completely drained before using them again. It's also a good idea to turn off any backup batteries.
● Try to avoid a static shock
Sparks, or electrostatic discharge (ESD), occurs when a static charge on one surface causes electrons to suddenly flow to another. This is because there is an imbalance of electrons between the two surfaces.
Since balance is so prized by Mother Nature, electrons are constantly being traded in order to maintain it. In order to avoid electrostatic discharge (ESD), it is recommended to use a grounded wrist strap and an ESD-safe mat.
Overcharged electrons can be dissipated by a wrist strap's conductive skin contact. Similarly, an electrostatic discharge (ESD) mat drains the charge from any object placed on it. If you're using a personal computer, the strap can be clipped to any section of the case that isn't covered with paint.
● Handle PCBs by their edges to reduce contamination
Soldering problems and even board failure via rusting or dendritic growth can be caused by contamination from a technician's hands. Silicone from hand creams or other sources can act as a barrier to contact regions, preventing the solder from forming a strong metallurgical bond during the soldering process.
When subjected to heat or physical force, the solder may adhere momentarily but then fall off. The best approach to avoid board failure is to wash your hands frequently and to use electronic-safe hand lotion.
Techniques for Fast, Reliable Desoldering
● For optimal heat conduction, make sure the tip of your soldering iron is always clean and tinned.
● Keep the board and its components from getting too hot for too long.
● Wick width must correspond with solder junction or contact pad width.
● For precision, line up the width of your soldering iron's tip with the width of your braid.
● Use a flux that is appropriate for the method of cleaning you intend to employ.
● Use a good flux remover to prevent corrosion on your board.
How may PCB repairs lessen heat stress on components?
The goal is to swiftly and safely remove the component by heating and removing the solder junction, without overheating the surrounding region. Removing faulty components requires heating only the solder joints necessary for removal, and doing so rapidly saves thermal stress on adjacent locations.
When only a small amount of solder needs to be removed, a desoldering station or solder wick can do the trick. When attempting to repair a PCB, methods that use heat, such as hot plates or hot air, increase the likelihood that the board may fail in the future.