From via-in-pad to vacuum plugging: The Evolution of PCB Resin Via Technology

From via-in-pad to vacuum plugging: The Evolution of PCB Resin Via Technology

PCB resin via plugging is a process for creating tiny holes in PCBs (printed circuit boards). It improves the quality and reliability of PCBs and meets the demands of high-density, high-frequency, and high-speed electronics manufacturing. This article will explain the definition, types, and development of PCB resin via plugging to help you understand this technology.

What is PCB resin via plugging?

PCB resin via plugging involves filling holes and defects in a PCB with a resin material to repair functional defects. Holes and defects in PCBs can occur during processes such as drilling, electroplating, and lamination, or they can be designed to achieve specific electrical properties. For example, via-in-pad (VIP) is a process where a via is placed directly on a pad. This saves horizontal space and increases PCB density and interconnectivity, but it can also cause resin to leak out of the via, impacting soldering quality and reliability. Therefore, a resin plugging process is used to fill the via with resin, followed by electroplating to form a metal cap to ensure continuity and smoothness.

What are the types of PCB resin via plugging?

Based on the resin filling method, PCB resin via plugging can be divided into the following two types:

Spraying: Resin material is sprayed onto the PCB, dried, and solidified to form a solid structure, filling holes and defects. This method is suitable for larger holes with fewer holes. It is simple to operate and low-cost, but it has low precision and is prone to bubbles and overflow.

Dip coating: The PCB is immersed in resin material, which is adsorbed and solidified to form a resin film, filling holes and defects. This method is suitable for smaller holes with more holes. It has high precision and fewer bubbles, but it is complex and expensive, requiring specialized equipment and processes.

What is the development history of PCB resin via plugging?

Early Stage: The origins of PCB resin via plugging can be traced back to the 1980s and 1990s. At that time, PCBs were mainly single-sided and double-sided boards, with a low number and density of holes. Spraying was commonly used for resin via plugging to improve the moisture and corrosion resistance of the PCBs, as well as their aesthetics.

Development Stage: With the advancement of electronic technology, the complexity and requirements of circuit boards have continued to increase. New types of circuit boards, such as multilayer boards, high-frequency boards, and high-density printed circuit boards (HDI boards), have emerged. The number and density of holes have increased significantly, and spray coating is no longer able to meet these requirements. Therefore, dip coating has emerged to achieve higher precision and efficiency, as well as better electrical performance.

Innovation Stage: Based on dip coating, the vacuum via plugging process has emerged to address issues such as bubbles and overflow. This involves placing the circuit board in a vacuum chamber and utilizing vacuum adsorption and degassing to better fill the holes with resin, improving resin quality and reliability. Furthermore, new resin materials and curing methods have emerged to suit different circuit board types and performance requirements.