PCB Technical - Countermeasures for silver layer defects in PCB manufacturing

Countermeasures for silver layer defects in PCB manufacturing
At present, the country has higher and higher requirements for environmental protection and greater efforts in link governance. This is a challenge but also an opportunity for PCB factories. If PCB factories are determined to solve the problem of environmental pollution, then FPC flexible circuit board products can be at the forefront of the market, and PCB factories can get opportunities for further development.
Immersion silver process printing is indispensable in the manufacture of circuit boards, but the immersion silver process can also cause shortcomings or scraps.

The formulation of preventive measures needs to consider the contribution of chemicals and equipment to various shortcomings in actual production, in order to prevent or eliminate the shortcomings and improve the yield rate.

The prevention of the Javanni effect can be traced back to the copper plating process of the previous process. For high aspect ratio holes and micro-vias, a uniform plating thickness helps eliminate the danger of the Javanni effect. Excessive corrosion or side corrosion during film stripping, etching, and tin stripping processes will promote the formation of cracks, and microetching solutions or other solutions will remain in the cracks. Nevertheless, the problem of the solder mask is still the most important reason for the Javani effect. Most of the defective boards with the Javani effect have side corrosion or the solder mask peeling off. This problem mainly comes from the exposure and development process. . Therefore, if the solder mask shows a "positive foot" after development, and the solder mask is completely cured, then the Javanni effect problem can be almost eliminated. To get a good immersion silver layer, the direction of immersion silver must be 100% metallic copper, each tank solution has a good through hole ability, and the solution in the through hole can communicate effectively. If it is a very fine structure, such as HDI board, it is very useful to install ultrasonic or jet in the pretreatment and immersion bath. Regarding the production management of the immersion silver process, controlling the micro-etching rate to form a smooth, semi-bright appearance can also improve the Javani effect. For original equipment manufacturers (OEM), the design of connecting large copper surfaces or high-aspect-ratio through holes with thin lines should be avoided as much as possible to eliminate the risk of the Javanni effect. For chemical suppliers, the silver immersion liquid should not be very aggressive, and the appropriate pH value must be adhered to, the speed of immersion silver should be controlled and the expected crystal structure can be generated, which can achieve the best anti-corrosion function with the thinnest silver thickness. .

Corrosion can be reduced by increasing the density of the coating and reducing the porosity. The use of sulfur-free material packaging, together with a seal to isolate the board from the air, also prevents the sulfur entrained in the air from touching the silver surface. It is best to store the packaged boards in an environment with a temperature of 30°C and a relative humidity of 40%. Although the shelf life of immersion silver plates is very long, the first-in-first-out principle must be followed when storing. Our factory is located in China. For decades, Shenzhen has been known as the world's electronics R&D and manufacturing center. Our factory and website are approved by the Chinese government, so you can skip the middlemen and buy products on our website with confidence. Because we are a direct factory, this is the reason why 100% of our old customers continue to purchase on iPCB.
No minimum requirements
You can order as little as 1PCB from us. We will not force you to buy things you really don't need to save money.
Free DFM
Before you pay in the most timely manner, all your orders will receive free engineering document review services by our well-trained professional and technical personnel.