The copper-free hole is also called the via hole, which belongs to the functional problem of the PCB circuit board. With the development of technology, the precision (aspect ratio) requirements of the PCB circuit board are getting higher and higher. It not only brings trouble to the PCB circuit board manufacturer ( Contradiction between cost and quality), and it has laid a serious quality hidden danger to downstream customers! The following editors will take a look at it with you, and I hope it can inspire and help relevant colleagues!

　　2. Classification and characteristics of copper-free holes

　　1. There are burrs in the holes of the pcb circuit board, and the vias are blocked. Because the hole wall is not smooth and has burrs during drilling, the copper sinking and the hole copper during electroplating are uneven. Once the customer debugs the copper-thin place of the through hole, it may burn out, resulting in an open circuit on the pcb circuit board and the through hole is blocked.

　　2. PCB circuit board electric copper thin hole without copper:

　　(1) The electric copper thin hole of the whole circuit board has no copper: the surface copper and the electric layer of the hole copper plate are very thin. The picture layer is wrapped;

　　(2) Copper-free thin holes in the inner plate of the hole: the electric layer of the surface copper plate is uniform and normal, and the electric layer of the inner plate of the hole shows a decreasing trend from the hole to the fracture, and the fracture is generally in the middle of the hole, and the copper at the fracture layer left

　　The right uniformity and symmetry are good, and the fracture is covered by the graph electric layer after the graph.

　　circuit board/circuit board

　　circuit board/circuit board

　　3. There is no copper in the PTH hole: the electrical layer of the surface copper plate is uniform and normal, the electrical layer of the inner plate of the hole is evenly distributed from the orifice to the fracture, and the fracture is covered by the electrical layer after the drawing. Repair the hole:

　　(1) Broken holes in copper inspection: the electrical layer of the surface copper plate is uniform and normal, the electrical layer of the hole copper plate has no tendency to be pointed, and the fracture is irregular, which may appear in the hole or in the middle of the hole, and rough convexities often appear on the hole wall. If it is not good, the fracture is covered by the graph electric layer after the graph is electrified.

　　(2) Etching and repairing the hole: the electrical layer of the surface copper plate is uniform and normal, the electrical layer of the hole copper plate has no tendency to be pointed, and the fracture is irregular, which may appear in the hole or in the middle of the hole, and roughness and convexity often appear on the hole wall. The electric layer of the board is not covered by the electric layer of the diagram at the fracture.

　　4. There is no copper in the plug hole: After the pcb circuit board pattern is electro-etched, there are obvious substances stuck in the hole, most of the hole walls are etched away, and the electrical layer of the pattern at the fracture does not cover the electrical layer of the board.

　　5. Repair the hole

　　(1) Broken holes in copper repair: the electrical layer of the copper plate on the surface of the pcb circuit board is uniform and normal, the electrical layer of the hole copper plate has no tendency to be pointed, and the fracture is irregular, which may appear in the hole or in the middle of the hole, and often occurs on the hole wall. There are rough bumps and other defects, and the fracture is covered by the map layer after the map is electrified.

　　(2) Etching and repairing the hole: the electric layer of the copper plate on the surface of the pcb circuit board is uniform and normal, the electric layer of the hole copper plate has no tendency to be pointed, and the fracture is irregular, which may appear in the hole or in the middle of the hole, and often occurs on the hole wall. There are defects such as rough bulges, and the electrical layer at the fracture is not covered by the electrical layer of the board.

　　6. There is no copper in the graphic hole: the graphic layer at the fracture does not cover the board electrical layer - the thickness of the graphic layer and the PCB board electrical layer is uniform, and the fracture is evenly broken; the graphic layer tends to be sharp until it disappears, and the board is The layer continues to extend a distance beyond the graphic layer and then disconnects.

　　3. Improvement direction

　　1. Materials (plates, potions);

　　2. Measurement (potion test, copper inspection);

　　3. Environment (variations caused by dirty, messy, and miscellaneous);

　　4. Methods (parameters, procedures, processes and quality control);

　　5. Operation (upper and lower panels, parameter setting, maintenance, exception handling);

　　6. Equipment (crown block, feeder, heating pen, vibration, pumping, filter cycle).

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