Optimizing Multilayer Board Lamination Quality: Strategies and Techniques
A. Selecting Appropriate PP and CU Foil Configuration:
- Meeting PCB user requirements involves considering dielectric layer thickness, dielectric constant, characteristic impedance, withstand voltage, and laminate surface smoothness.
- PP Selection Criteria:
- Resin capability to fill gaps in printed wires during lamination.
- Effective elimination of air and volatile matter between laminations.
- Provision of necessary dielectric layer thickness for multilayer boards.
- Ensuring bonding strength and a smooth appearance.
- Recommended PP Configurations:
- For 4-layer laminates: 7628, 7630, or 7628+1080, 7628+2116.
- For >6 layers: Mainly 1080 or 2116, with 7628 for increased dielectric layer thickness.
- Symmetrical PP placement for mirror effect and prevention of plate bending.
- CU Foil Quality:
- Configured based on PCB user requirements, adhering to IPC standards.
B. Inner Core Board Processing Technology:
- Inner core board treatment involves black oxidation and browning processes.
- Black Oxidation Treatment:
- Forms a black oxide film on inner copper foil.
- Thickness of the black oxide film: 0.25-4.50mg/cm2.
- Browning Process (Horizontal Browning):
- Forms an organic film on inner copper foil.
- Functions of Treatment Process:
- Increases contact surface between inner copper foil and resin, enhancing bonding force.
- Improves effective wettability of molten resin to copper foil.
- Prevents decomposition of curing agent dicyandiamide in liquid resin at high temperatures.
- Enhances acid resistance during wet processes, preventing pink circles.
This comprehensive approach outlines key strategies for improving multilayer board lamination quality, addressing material selection and inner core board processing techniques.
