PCBA Tech - PCBA hole wall has copper particles and copper wires

Summary of content: If there is a hole in the copper processing process, there are copper particles and copper wires on the PCBA hole wall, what is the problem with the potion? What is the SAP process?

The industry generally defines primary copper as the process of removing three glue residues, chemical copper and a complete printing plate. Holes, copper particles and copper wires will occur in the PCBA hole wall. These problems are usually not copper problems, but problems caused by chemical copper precipitation or slag removal processes. In the process of excrement, the circuit board will undergo three treatment processes of filler, oxidant and reducing agent. If the solution ages during the reduction process, permanganate residues may remain on the PCBA pore walls and cannot be completely removed. When this type of circuit board enters the electroless copper plating process, it will be corroded by the micro-etching solution, resulting in partial detachment. At this time, the active layer formed by the porogen will be destroyed, resulting in severe growth of chemical copper and rupture of the pores.

Of course, the chemical process of copper itself can also cause opening problems. For example, the copper chemical activity is insufficient, the hole depth is too large, chemical copper cannot be processed, the use of metal modifiers, palladium holes and colloid problems, these will also affect the PCBA hole wall quality. If the drill is of poor quality, the hole is more likely to break. Especially if the PCBA hole wall is too thick, it will cause problems such as poor cleaning and residual liquid, which will affect the precipitation of chemical copper. Holes are particularly prone to occur. As for the occurrence of electroplating problems such as copper particles and copper wires, the most common source of problems is poor brushing and copper chemical roughness. As far as the improvement of chemical copper is concerned, the improvement of water washing, the integrity of the extraction rack and the substitution of chemical liquids are feasible methods. Among them, it is particularly necessary to avoid mixing the copper chemical micro-engraving and the extraction grating treatment tank. Such problems are usually found in foundries and occur in factories with restricted workplaces. When the two are mixed, the colloid left in the peeling grid process will settle into the hole, and the PCBA hole wall will be rough. From this point of view, in order to eliminate these problems, not only a mixed storage tank is needed, but also palladium colloid and water washing filtration circulation system should be paid attention to. Only in this way can the roughness of the PCBA hole wall be minimized.

If PCBA products allow, the company can also consider using a direct coating process. This type of process does not have the problem of palladium colloids, but due to the structure of the circuit board and past historical experience, some system suppliers have restricted the use of this technology. This is the first step in establishing the process, please consider this part. Processes such as "shadows" and "black holes" are representative of this type of technology, and they can also have the function of enhancing the copper particles on the PCBA hole walls.

The full name of SAP is "SemiAdditiveProcess", because the general circuit production is divided into two methods: full etching and partial etching. This partial etching method has the ability to manufacture stronger circuits and can produce finer circuits. Therefore, if the external circuit of the ordinary circuit board is thin, you can consider using the SAP process to make the circuit. In recent years, the requirements for circuit production have become more and more precise. Therefore, some circuit boards are manufactured using an all-chemical copper-based method. Today, most industries use the so-called SAP process, which is this type of practice.

In fact, all circuit board production methods can be called SAP processes, but their basic copper thicknesses are different, but the current industry believes that only the process in which the basic copper is pure chemical copper should be called. In addition, in the field of structural load panels, the industry partly uses ultra-thin copper cladding to make circuits. At this time, a different name "M-SAP" was added. This M stands for metal, which means copper metal. At this time, the manufacturing process is not the basis of pure copper, but ultra-fine copper. The above is for reference only.