What is the rework process of fingerprint recognition flexible and rigid board

In the fingerprint recognition Rigid-flex PCB production process, rework is an inconspicuous but very important process. Many fingerprint recognition Rigid-flex PCBs with defective quality have been "reborn" through rework in this production process and become qualified products. Today, we will explain the rework process in the fingerprint recognition Rigid-flex PCB production process in detail.

1. The purpose of fingerprint recognition Rigid-flex PCB rework

(1) In the process of reflow soldering and wave soldering, defects such as open circuit, bridging, virtual soldering and poor wetting are required to be repaired manually with the help of certain tools to achieve the effect of removing various solder joint defects, so as to obtain Qualified fingerprints identify the solder joints of the Rigid-flex PCB.

(2) Repair welding for missing components.

(3) Replace the wrongly placed and damaged components.

(4) After the single board and the whole machine are debugged, replace the inappropriate components.

(5) Fingerprint recognition Rigid-flex PCB machine should be repaired if problems are found after leaving the factory.

2. Determine the solder joints that need to be repaired

(1) Positioning electronic products

To determine what kind of solder joints need to be repaired, you should first locate the electronic product and determine which level of product the electronic product belongs to. Level 3 is the highest requirement. If the product belongs to Level 3, it must be tested according to the highest standard; if the product belongs to Level 1, it can be tested according to the lowest standard.

(2) To clarify the definition of "good solder joints"

Excellent solder joints refer to solder joints that can maintain electrical performance and mechanical strength during the use environment, method and life period considered when designing electronic products; as long as this condition is met, there is no need to rework.

(3) Measure with IPC-A610E standard. Rework is not required if the conditions for acceptable grades 1 and 2 are met.

(4) Detected by IPC-A610E standard, defect grades 1, 2, and 3 must be repaired.

(5) Use the IPC-A610E standard for testing, and the process warns that Levels 1 and 2 must be repaired.

Note: Process Alert 3 means that it is safe to use despite the presence of non-compliant conditions. Therefore, in general, the process warning level 3 can be treated as acceptable level 1, and it is not necessary to return for repair.

3. Precautions for repairing

(1) Do not damage the pads.

(2) Ensure the usability of components. If it is a double-sided welding component, a component needs to be heated twice; if it is repaired once before leaving the factory, it needs to be heated twice; if it is repaired once after leaving the factory, it needs to be heated twice. Based on this calculation, a component must be able to withstand 6 high-temperature soldering to be considered a qualified product. For high-reliability products, components that have been repaired once may no longer be used, otherwise reliability problems will occur.

(3) The surface of the component and the surface of the fingerprint recognition soft and hard combination board must be kept flat.

(4) The process parameters in production should be simulated as much as possible.

(5) Pay attention to the number of potential electrostatic discharge hazards, and perform operations according to the correct welding curve during repair.