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Common problems and countermeasures in the production process of Pcb and fpc soft circuit boards

Shenzhen Inno Circuit Co.,Ltd | Updated: Jun 05, 2018

Common problems and countermeasures in the production process of Pcb and fpc soft circuit boards


With the conversion of surface solder to lead-free type, the soldering temperature of the circuit board is required to rise, and the thermal shock resistance of the surface solder resist layer is required to be higher and higher. The terminal surface treatment and the solder resist layer (ink, cover film) Peeling strength of the ), and the bond strength to the base copper are more and more demanding, we need a pretreatment process with better effect to do the protection. By improving our processes to increase product yields, we can achieve profit growth. High-quality pre-treatment potions can undoubtedly help us at a low cost.


  This article mainly introduces the problems and countermeasures often encountered in the production process of PCB rigid circuit board and FPB flexible circuit board. First, the side etching occurs during the etching process after dry film or wet film processing at the line section, and the etchback phenomenon occurs. , resulting in insufficient line width or uneven lines. The reasons are nothing more than improper selection of dry and wet film materials, improper exposure parameters, and poor exposure performance. Development, adjustment of the etched section nozzles, improper adjustment of relevant parameters, improper concentration of the liquid medicine, improper transmission speed, etc. may cause problems. However, we often find that after checking the above parameters and related equipment performance, there is no abnormality. However, circuit board over-etching, etchback and other problems still occur during board fabrication. what is the root cause? 


  Second, when doing PCB pattern electroplating, PCB, FPC terminal surface treatment such as gold, electric gold, electric tin, chemical tin, etc., we often find that the board made in the edge of the wet and dry film or solder mask edge seepage The phenomenon of plating, or the appearance of most of the boards, or parts of the board, will cause unnecessary scrap or unfavorable conditions to bring unnecessary troubles to the processing of the post-segment, and eventually to end-of-life. ! The reason for this analysis is that we often think of wet and dry film parameters and problems with material properties; solder resists such as inks used for hard plates, problems with cover films for soft boards, or problems in printing, lamination, curing, etc. . Indeed, each of these places can cause this problem to occur. Then we are also puzzled that after checking the above steps, there are no problems or problems, but the phenomenon of seepage is still present. What are the reasons for not finding out?


  Third, the circuit board will be tested on tin before shipping. Customers will of course use tin soldering components when they are in use. It is possible that both stages will occur, or that tin dipping or soldering will occur at a certain stage. The substrate will be peeled off. When the tape is used to test the peel strength of the ink, the ink will appear when the peel strength of the cover sheet is tested. Obviously peeled off or the problem of insufficient or uneven film peeling strength, this type of problem is absolutely unacceptable to the customer, especially for precision SMT placement. Once the solder mask layer is peeled off during the soldering process, it will not be able to mount the original parts accurately. This will cause customers to lose a large number of components and lose their jobs. The circuit board factory will face great losses such as deductions, feeds, and even lost customers. So what do we usually do in those areas when we encounter such problems? We usually analyze whether it is a problem of solder resist (ink, cover film) materials; whether it is a problem of screen printing, lamination, or curing; is there a problem with electroplating solutions? and many more. . . So we usually order the engineer to look for the cause from these sections—and improve it. We also think of the reason for the weather? Recently more humid, the plate absorbs moisture? (Substrate and barriers are susceptible to moisture absorption) After some hard work, how much can be achieved, the problem is temporarily solved on the surface. However, inadvertently, such problems have occurred again. What is the reason? The sections that may have problems have clearly been checked and improved. What else is not noticed?


  For the above belongs to the PCB, FPC industry, a wide range of puzzles, problems. We conducted a large number of tests and research, and finally found that an important reason for the problems of poor circuit, permeation plating, delamination, foaming, and insufficient peel strength turned out to be the pre-processing part. Including dry and wet film pretreatment, solder mask treatment, plating pretreatment and other multi-section pre-processing section. Here, perhaps many industry people can't help laughing. Pre-treatment is the easiest, pickling, degreasing, micro-etching. Which is the same as the pre-treatment syrup, performance, parameters and formula, many technical personnel in the industry are clear.