There are holes broken, there are copper particles and copper wires on the walls of the holes. What are the problems with the potions?

- Dec 19, 2019-

There are holes broken, there are copper particles and copper wires on the walls of the holes. What are the problems with the potions?

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

 Primary copper as defined by general industry refers to the three processes of removing glue residue, chemical copper, and full-plate plating. Hole breakage, copper particles and copper wires occur in the hole wall. These problems are usually not a copper problem, but a problem caused by the precipitation of chemical copper or the process of removing slag. In the process of removing the dregs, the circuit board will be subjected to three treatment processes of bulking agent, oxidizing agent and reducing agent. If the solution is aged during the reduction process, permanganate residues may be left on the wall of the pores and not completely removed. When this kind of circuit board enters the process of chemical copper, it will be attacked by the micro-etching solution to cause local peeling off. At this time, the active layer created by the pore-forming agent will be destroyed, which will cause the chemical copper to grow poorly and cause holes to break.

Of course, the chemical copper process itself may also cause pore breaking problems, such as insufficient chemical copper activity, too high pore depth, chemical copper cannot be processed, problems with the use of pore modifiers and palladium colloids, and these will also affect the quality of the pore wall. If the quality of the drill hole is poor, hole breakage is more likely to occur. Especially if the hole wall is too thick, it will cause problems such as poor cleaning and residual liquid affecting the precipitation of chemical copper. It is particularly easy for hole breakage to occur. As for the occurrence of electroplating problems such as copper particles and copper wires, the more common sources of problems are poor brushing and chemical copper roughness. In terms of improving chemical copper, improving water washing, stripping rack integrity, and chemical liquid replacement are all feasible methods. Among them, it is especially necessary to avoid mixing of chemical copper micro-etching with stripping rack treatment tanks. Such problems are often found in foundry and Occurred in factories with restricted workplaces. When the two are mixed, the colloid remaining in the peeling rack treatment will precipitate in the hole, and the hole wall will be rough. From this perspective, to eliminate such rough problems, not only should the tanks be mixed, but also pay attention to the palladium colloid and water-washing filtration circulation system. Only in this way can the pore wall roughness be minimized.

Businesses can also consider using a direct plating process when the product allows it. This type of process does not have the problem of palladium colloid, but some system vendors restrict the use of this technology because of the circuit board structure and past historical experience. This is the first step when setting up a process Consider the part. Processes such as Shadow and Black Hole are representative of this type of technology, and may also have the function of improving the copper particles on the hole wall.

SAP's full name is "SemiAdditiveProcess", because general circuit production is divided into two methods: full etching and partial etching. This method of partial etching has a stronger circuit making ability and can produce finer circuits. Therefore, if the external circuit of the general circuit board is thin, the SAP process may be considered for making 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 approach. At present, most of the industry refers to the so-called SAP process, which refers to such practices.

In fact, all methods of circuit plating production can be called the SAP process, but their base copper thickness is different, but currently the industry thinks that only the process where the base copper is pure chemical copper should be called like this. In addition, in the field of structural loading boards, the industry also partially uses ultra-thin copper skin to make circuits. At this time, a different designation "M-SAP" has been added. This M refers to Metal, which means copper metal. At this time, the manufacturing process is not Then it is the basis of pure copper, but ultra-thin copper. The above is for reference only.

Previous:FPC shape and hole processing-double-sided FPC manufacturing process Next:Essential electronic circuit knowledge selection for electronic engineers