In the 1990s, a Japanese company developed a resin that directly plugged the hole and then plated copper on the surface, mainly to solve the problem of air blowing in the green oil plug hole. Intel applied this process to Intel's electronic products, giving birth to the so-called POFV (some factories also called Via on pad) process.
In recent years, the process of resin plugging has been widely used in the circuit board industry, especially for products with high layers and thicker boards. People hope to use resin plug holes to solve a series of problems that cannot be solved by using green oil plug holes or press-fit resin filling. However, due to the characteristics of the resin used in this process, many difficulties need to be overcome in the production to achieve good quality resin plugging products.
The role of the resin plug hole of the circuit board:
The process of using resin plug holes for circuit boards is often due to BGA parts, because traditional BGA may make VIA between PAD and PAD to the back to route the wiring, but if the BGA is too dense and the VIA cannot go out, you can drill directly from the PAD The holes are made via vias and routed to other layers, and then the holes are filled with resin and copper-plated into PAD, which is commonly known as the VIP process (via in pad). If you only make via on the PAD without plugging the holes with resin, It is easy to cause leakage of tin, resulting in short circuit on the back and empty solder on the front.
The process of resin plug holes for circuit boards includes drilling, electroplating, plugging, baking, and grinding. After drilling, the holes are plated through, then the resin is plugged and baked, and finally the resin is polished and polished. It does not contain copper, so another layer of copper is needed to turn it into PAD. These processes are all done before the original circuit board drilling process, that is, the holes of the fortress hole are processed first, and then other holes are drilled. Follow the original normal manufacturing process.
If the plug hole is not plugged properly and there are bubbles in the hole, because the bubbles are easy to absorb moisture, the board may burst when the board is passed through the tin furnace. However, if there are bubbles in the hole during the plugging process, the bubbles will cause the resin to be baked. Extrusion, resulting in a situation where one side is recessed and the other is protruding. At this time, defective products can be detected, and the board with bubbles does not necessarily burst, because the main cause of the burst is moisture, so if the board or the board just left the factory The upper part is baked, and generally speaking, it will not cause the board to burst.