Analysis of abnormal processing of PCB circuit board

It will inevitably encounter some defective process of PCB circuit board, 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 hole broken state is a point distribution, rather than the whole ring opening phenomenon, it is called point hole breaking, also called it "wedge shaped hole broken."". The common causes are caused by the bad treatment of the removing slag process. When the PCB circuit board is processed, the process of removing the slag will be processed by a leavening agent, and then a strong oxidizing agent "permanganate" will be used to remove the slag and produce a microporous structure. After the removal process, the residual oxidant is removed by reducing agent, and the typical formula is treated with acid liquid.


Since the residue is not seen again after the treatment of the waste residue, the monitoring of the reducing acid solution has been neglected, which may allow the oxidizer to remain on the wall. 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.


The damaged pore walls do not react with subsequent PD colloids and chemical copper treatment, and these regions show a copper free appearance. If the foundation is not established, the plating copper will not be covered completely and the point hole will be broken. Such problems have occurred in many circuit boards in the process of circuit board processing, and pay more attention to the process of removing slag, and the monitoring of syrup should be improved.


PCB circuit board processing in each link we need to strictly control, because the chemical reaction sometimes in our corner of attention does not occur slowly, thereby undermining the entire circuit. We must be on guard against this hole.


Bare plates are also often referred to as "printed circuit boards Printed, Wiring, Board (PWB)."". The substrate of the board itself is made of insulation, heat insulation and material which is not easily bent. 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 called wires (conductor, pattern), or wiring, and are used to provide circuit connections for parts on the PCB board.


Usually the color of the PCB board is green or brown, which is the color of the solder (solder, mask). The utility model is an insulating protective layer, which can protect the copper wire, prevent the short circuit caused by wave soldering and save the amount of soldering tin. A layer of screen printing (silk, screen) is also printed on the solder resist. Usually, letters and symbols (mostly white) are printed on it to mark the location of the parts on the board. The screen printing surface is also called the legend.


When manufacturing the final product, an integrated circuit, transistor, diode, passive component (such as resistors, capacitors, connectors, etc.), and various other electronic components will be installed. By connecting wires, electronic signals can be connected and functioning.


 

(Source: internal information)

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