PCBA Tech - How to disassemble the BGA chip in SMT processing?

When disassembling the BGA, it is necessary to do a good job of component protection. When desoldering, put a cotton ball soaked in water on the adjacent IC. Many plastic power amplifiers and soft-packaged fonts have poor high temperature resistance, and the temperature is not easy to be too high during blow welding, otherwise, they will be easily blown out.

Put an appropriate amount of flux on the IC to be disassembled, and blow it into the bottom of the IC as much as possible, so that the solder joints under the smt chip will melt evenly. Adjust the temperature and wind of the hot air gun. Generally, the temperature is 3-4 levels, and the wind is 2-3 levels. The air nozzle is moved about 3cm above the chip to heat until the tin beads under the chip are completely melted. Use tweezers to pick up the entire chip. Note: When heating the IC, blow around the IC, don't blow the middle of the IC, otherwise the IC will bulge easily. Do not heat the board for too long, otherwise the circuit board will be blistered.

After the BGA chip is removed, there is excess tin on the pad of the chip and on the board. At this time, add enough solder paste on the PCBA board, and use an electric soldering iron to remove the excess solder on the board, and the tin can be properly applied Make each solder foot of the circuit board smooth and round, and then use thinner to clean the chip and the flux on the board. Be especially careful when removing the solder, otherwise the green paint on the pad will be scraped off or caused The pad comes off.

SMT patch processing needs to pay attention to problems

1. Template design guidelines. It provides guidelines for the design and manufacture of solder paste and surface mount adhesive coating templates. It also discusses template design using surface mount technology, and introduces hybrid technology with through-hole or flip chip components. Including overprinting, double printing and staged template design.

2. Joint standards for the development of electrostatic discharge control procedures. Including the necessary design, establishment, implementation and maintenance of electrostatic discharge control procedures.

3. Semi-aqueous cleaning manual after welding. Including all aspects of semi-aqueous cleaning, including chemical, production residues, equipment, technology, process control, and environmental and safety considerations.

4. Desktop reference manual for through-hole solder joint evaluation. Detailed description of components, hole walls and welding surface coverage according to standard requirements, in addition to including computer-generated 3D graphics. Covers tin filling, contact angle, tin dip, vertical filling, solder pad coverage, and numerous solder joint defects.

5. After PCBA soldering, it becomes water cleaning manual. Describe the cost of manufacturing residues, the types and properties of aqueous cleaning agents, the process of aqueous cleaning, equipment and techniques, quality control, environmental control, employee safety, and cleanliness measurement and measurement.