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Cleaning process and prevention of pollutants in double-sided pcb board manufacturing

2019-10-12 23:27:39 Juding Circuit Technology 330

   Mechanical cleaning, which refers to the physical removal of residues from the outer surface by a mechanical process, reveals a fresh clean surface. This method essentially uses a grinding method, and the difference between the various methods is how to achieve the grinding. In all the grinding and cleaning processes, there is a danger that the particles produced by the grinding will be embedded in the metal surface and the insulating substrate. Reflected on the double-sided metal surface, mainly due to reduced solderability and poor wettability. This can be achieved by first slightly corroding the metal surface (eg, the metal surface is copper, which can be etched away with a persulfate solution to a thickness of 3 pm to obtain a clean surface), followed by rinsing and rinsing with high energy water to remove residual adsorbed particles. There are four main ways for non-weldable surfaces: abrasive brushing, pad brushing, sandblasting, and soft sanding.


Double panel manufacturing cleaning process


   It should be noted that the double-sided solderability surface should not be cleaned by grinding. The metal surface has been tinned, reflowed, leveled, or has been coated with a layer of metal (such as gold), which is a solderable surface. The residue of the grinding may affect its solderability or surface insulation resistance. These cleaning techniques are only applicable to double-layer laminates prior to the formation of the primary pattern or to the plating pattern before the solder mask. This cannot be used after assembly of any components, which is determined by the nature of the grinding.


   Prevention of Contaminants Under normal circumstances, most dual-panel manufacturers do not take any tests at this stage because the size of the sheets is too large for general operation and most cleaning equipment. This process is to cut a large board into the usual operating dimensions, such as cutting the large board into four or six pieces, and punching or drilling according to the pre-made procedure.


    Contaminant shearing and drilling of raw materials may carry metal shavings and crushed debris. Surface pretreatment is the first process of cleaning contaminants on the surface of the board. Double-layer laminate release agents and other greases adhere to the surface of the copper clad laminate, and many suppliers use rust inhibitors to protect the copper surface. Be sure to remove them before the next step.


     Prevention At this stage, some operators do not take special cleaning operations unless it is a "print-etch" board process that drills after etching.


Prevention of double panel pollutants


    Metal and laminate debris is formed when a double-sided copper clad is drilled or punched. In addition, residues of packaging materials and particles from the environment may also be sources of contaminants. In particular, if laser micropore processing is used, it is possible to leave a residue around each hole.


    Drilling Contamination All contaminants introduced by the borehole are particles. Prevention If the debris is not removed, it will affect the quality of the subsequent process, so it is very important to avoid the debris from the previous process to the next process. Vacuum or compressed air purge is a viable method, and it is also feasible to use a solvent or water solvent in combination with ultrasonic waves. If the burr is removed first, the double-sided board surface may be better.


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