First, the process factors of the soft and hard board factory:

　　1. The circuit design of the flexible and rigid board is unreasonable. Designing too thin circuits with thick copper foil will also cause excessive circuit etching and copper rejection.

　　2. A local collision occurs in the process of the flexible and rigid board, and the copper wire is separated from the base material by external mechanical force. This defect is manifested as poor positioning or orientation, and there will be obvious twists in the dropped copper wire, or scratches/impact marks in the same direction. Peel off the bad copper wire and look at the rough surface of the copper foil. It can be seen that the color of the rough surface of the copper foil is normal, there will be no bad side corrosion, and the peeling strength of the copper foil is normal.

　　3. The copper foil is over-etched. The electrolytic copper foil used in the market is generally single-sided galvanized (commonly known as ashing foil) and single-sided copper-plated (commonly known as reddish foil). The common copper rejection is generally more than 70um of galvanized copper Foils, red foils and ashing foils below 18um have basically not experienced batch copper rejection.

　　When the customer's circuit is designed to pass the etching line, if the copper foil specification is changed but the etching parameters remain unchanged, the copper foil will stay in the etching solution for too long. Because zinc is inherently an active metal, when the copper wire on the flexible and rigid board is soaked in the etching solution for a long time, it will inevitably lead to excessive side etching of the circuit, causing the backing zinc layer of some thin circuits to be completely reacted. The material is detached, that is, the copper wire falls off.

　　Another situation is that there is no problem with the etching parameters of the flex-rigid board, but the washing and drying after etching are not good, so that the copper wire is also surrounded by the etching solution left on the surface of the flex-rigid board. If it is not treated for a long time, it will also produce The copper wire is over-etched and the copper is thrown away. This situation is generally concentrated on thin lines, or in humid weather, similar defects will appear on the entire flexible and rigid board. Peel off the copper wire to see the color of its contact surface with the base layer (the so-called roughened surface). It has changed, and the color of the normal copper foil is different. The original copper color of the bottom layer is seen, and the peeling strength of the copper foil at the thick circuit is also normal.

　　2. Reasons for the laminate process:

　　Under normal circumstances, as long as the laminate is hot-pressed for more than 30 minutes in the high temperature section, the copper foil and the prepreg are basically completely combined, so the pressing generally does not affect the bonding force between the copper foil and the substrate in the laminate. However, in the process of stacking and stacking laminates, if PP is polluted, or the rough surface of copper foil is damaged, it will also lead to insufficient bonding force between copper foil and substrate after lamination, resulting in positioning (only for large boards and language) or sporadic copper wires fall off, but there is no abnormality in the peeling strength of copper foil near the disconnected wires.

　　3. Reasons for laminate raw materials:

　　1. It is mentioned above that ordinary electrolytic copper foils are galvanized or copper-plated wool foil products. If the wool foil is produced with an abnormal peak value, or when galvanized/copper-plated, the coating dendrites are not good, causing the copper foil itself. The peeling strength is not enough. The copper wire will fall off when it is impacted by external force when the poor foil pressed sheet is made into a rigid-flex board and inserted in the electronics factory. This kind of poor copper rejection will not cause obvious side etching after peeling the copper wire to see the rough surface of the copper foil (that is, the surface in contact with the substrate), but the peeling strength of the copper foil on the whole surface will be very poor.

　　2. Poor adaptability between copper foil and resin: Some laminates with special properties currently used, such as HTg sheets, are generally PN resins as curing agents due to different resin systems. The resin molecular chain structure is simple, and when curing The degree of crosslinking is low, and it is necessary to use copper foil with special peaks to match it. When producing laminates, the use of copper foil does not match the resin system, resulting in insufficient peel strength of the metal-clad sheet metal foil, and poor copper wire falling off when inserting.

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