The SP200501 document provides detailed starting point compensation factors for Rogers RO4350B™ laminates. These factors are essential for optimizing PCB fabrication processes and ensuring precise dimensional control during etching, drilling, and lamination. By accounting for the material’s inherent properties and processing behavior, manufacturers can achieve high precision in RF and microwave circuit designs.

Key Considerations

1. Material Characteristics of RO4350B™:
   • Dielectric constant (Dk): 3.48 ± 0.05
   • Low dissipation factor (Df): 0.0037 @ 10 GHz
   • Excellent mechanical and thermal stability.
2. Dimensional Stability:
   • RO4350B laminates exhibit minimal dimensional movement during processing, but compensation factors ensure better precision in multilayer stack-ups and high-frequency designs.
3. Processing Environment:
   • Standard PCB manufacturing techniques can be used, but temperature, pressure, and chemical treatments need adjustments for optimal results.

Starting Point Compensation Factors

Process Step	Compensation Factor	Notes
Etching	0.1 mil/inch per side	Adjust for copper thickness and etching depth.
Drilling	Oversize by 2 mils	Accounts for resin shrinkage and hole wall plating.
Lamination	Shrinkage: 0.02% – 0.05%	Depends on press conditions and material thickness.
Imaging	±1 mil per inch	Ensure proper scaling for artwork and films.

Process Guidelines

1. Etching:
   • Control etch parameters to maintain consistent line widths and spacings.
   • Use compensation factors for signal integrity in high-frequency designs.
2. Drilling:
   • Pre-drill size compensation ensures final hole dimensions meet design requirements.
   • Use high-speed drills and optimized speeds to minimize burrs.
3. Lamination:
   • Maintain uniform pressure and temperature during multilayer lamination.
   • Use balanced stack-ups to reduce warping or bowing.
4. Artwork Scaling:
   • Apply artwork scaling based on material movement during processing.
   • Verify scaling factors with test runs to ensure accuracy.

Application Example

For a 10-layer PCB using RO4350B laminates:

1. Lamination:
   • Calculate overall shrinkage based on the material’s thickness and processing conditions.
2. Drilling:
   • Apply oversizing compensation for via holes, ensuring proper plating thickness post-processing.
3. Etching:
   • Use compensation factors for conductor width reduction during chemical etching.
4. Verification:
   • Validate compensation factors with a prototype run to confirm dimensional accuracy.

The SP200501 guidelines for RO4350B starting point compensation factors ensure precise control of critical dimensions during fabrication. By incorporating these factors into your PCB manufacturing processes, you can optimize performance and reliability for high-frequency and RF applications.