It will inevitably encounter some defective process of PCB circuit board processing, there may be errors caused by the machine, there may be a man-made causes, such as sometimes is called a abnormal state of broken hole, concrete analysis of specific situations.
If the state of the hole is a point distribution rather than the whole circuit of the phenomenon, it is known as the point hole broken, it was also called "wedge shaped hole broken". Common causes, resulting in the process of removing the residue of glue. When the PCB circuit board is processed, the process of removing the glue residue is first treated with a leavening agent, and then the strong oxidant is used for the erosion of the permanganate. After the removal of the residual oxidant, it depends on the removal of reducing agent, the typical formula using acidic liquid treatment.
Due to the treatment of the gum residue, and will not see residual gum residue problem, the general neglect of the monitoring of the reduction of acid, which may allow the agent to stay on the wall surface. After the circuit board into the electroless copper, after the whole hole agent processing circuit board micro etching, then the residual oxidant again by acid soaking and let the resin stripping residual oxidizing agent area, and at the same time will destroy the whole hole agent.
At the same time, the destruction of the hole wall, in the subsequent palladium colloid and chemical copper treatment will not react, these areas will show no copper analysis appears. Based on the establishment of copper plating, of course, can not be completely covered and produce a hole broken point. This kind of problem has been in a lot of circuit board factory in the circuit board processing happened, pay more attention to the process of the addition of slag slag reduction process monitoring should be improved.
PCB circuit board in the process of each link we need to strictly control, because the chemical reaction sometimes in the corner we do not pay attention to the slow, thus undermining the entire circuit. This hole in the state to be vigilant.
Bare boards (no parts above) are also often referred to as "printed circuit boards Printed Wiring Board (PWB)". The board itself is made of insulating and heat insulating material which is not easy to bend. The fine lines can be seen on the surface of the material is copper foil, copper foil is covered in the original on the board, and in the manufacturing process partly etched off, left to the part of a network of thin wires. These lines are referred to as pattern (conductor) or wiring and are used to provide circuit connections on parts of the PCB board.
Usually the color of the PCB board is green or brown, which is the color of solder (solder mask). It is an insulating protective layer, which can protect the copper wire, prevent the short circuit caused by the wave welding, and save the amount of soldering tin. A layer of screen printed surface (silk screen) will be printed on the solder mask. It is usually printed on words and symbols (mostly white) to indicate the position of each part on the board. Screen printing surface is also known as the icon surface (legend).
In the final product, it will be integrated circuits, transistors, diodes, passive components (such as: resistors, capacitors, connectors, etc.) and a variety of other electronic components. By connecting the wires, electronic signals can be formed and connected.