I. PCBA rework process purpose
1. Reflow soldering machine, wave soldering equipment process produced by open circuit, bridging, false soldering and poor wetting and other solder joint defects, the need to manually with the help of the necessary tools (such as: BGA rework station, X-ray machine, high power microscope) to remove a variety of defects in solder joints after trimming to obtain a qualified pcba solder joints.
2. Patch soldering missed components.
3. Replacement of paste position and damaged components.
4. Veneer and machine debugging also have some need to replace the components.
II. The need to rework the solder joints
How to determine the need to rework the solder joints?
1. First of all, we should give the electronic product positioning, determine what kind of solder joints need to rework, to determine the electronic product belongs to which level of the product. 3 is the highest requirements, must be in accordance with the highest level of standard testing. If the product belongs to level 1, according to the lowest level of standards can be.
2. To clarify the definition of “good solder joints”. Excellent SMT solder joints refers to the design considerations in the use of the environment, the way and the life of the solder joints to maintain electrical properties and mechanical strength, therefore, as long as this condition is met, there is no need to rework.
III. Rework considerations
1. Do not damage the pads.
2. Availability of components. If double-sided welding, a component needs to be heated twice: If the factory reworked 1 time, it needs to be heated twice more (disassembly, welding, each heated 1 time). If it is reworked once after shipment, it needs to be heated twice more. According to this projection, the requirements of a component should be able to withstand 6 high-temperature welding is considered a qualified product. Therefore, for high-reliability products, may be after 1 repair components can not be used again, otherwise reliability problems will occur.
3. The component surface and PCB surface must be flat.
4. Simulate the process parameters of the production process as much as possible.
5. Pay attention to the number of potential electrostatic discharge hazards.
Post time: Sep-12-2024