To fully address the issue of air bubbles in the lamination process of multi-layer boards and enhance the bonding between layers, the use of vacuum lamination technology is becoming increasingly inevitable. Pin-free positioning technology (MASSI. AM) has been widely adopted for 4 to 6-layer boards, while X-ray positioning drilling is utilized to enhance the accuracy of multi-layer boards. In addition to traditional electric heating and hot oil heating methods, the introduction of lamination technology using copper foil resistance direct heating has significantly reduced energy consumption and improved lamination quality through uniform heating.
As electronic technology continues to advance, the development of printed circuit technology has progressed, leading to an increasing proportion of multi-layer boards. The performance requirements for multi-layer boards have evolved towards high precision, fine, large, and small. Lamination is a critical process in the production of multi-layer boards, and the control of lamination quality has become increasingly crucial. Therefore, a better understanding of the multi-layer board lamination process is necessary to ensure its quality. Drawing from years of lamination practice, the following recommendations are made to improve the lamination quality of multi-layer boards from a process technology perspective:
A. Design inner core boards that meet lamination requirements:
Select core board thickness based on total multi-layer board thickness, ensuring consistency in thickness, minimal deviation, and alignment of warp and weft directions.
Maintain spacing between core board external dimensions and effective units to prevent unnecessary board bending and material wastage.
Carefully design positioning holes, considering their quantity and placement to reduce deviation between layers and facilitate manufacturing processes.
Ensure inner core boards are free from open circuits, short circuits, oxidation, and residual film.
B. Select appropriate PP and CU foil configurations to meet PCB user requirements:
Consider characteristics such as dielectric layer thickness, dielectric constant, characteristic impedance, withstand voltage, and laminate surface smoothness when choosing PP.
Recommend PP configurations such as 7628, 7630, or 7628+1080, 7628+2116 for 4-layer laminates, and 1080 or 2116 for multi-layer boards with more than 6 layers.
Select CU foil models based on PCB user requirements, ensuring quality complies with IPC standards.
Ultimately, these recommendations aim to enhance the lamination quality of multi-layer boards by addressing the design of inner core boards and the selection of PP and CU foil configurations.