HDI glass fibre for added strength

AGY, a USA-based producer of glass fibre yarns and high-strength glass fibre reinforcements, has recently introduced S-3 HDI glass fibre containing a patent-pending glass composition that has been especially designed for use in high performance PCBs.

Designed to meet the demanding technical requirements of HDI technology in PCBs – especially integrated circuit package substrates – S-3 HDI fibres enable the production of PCB laminates that have a significant reduction in the co-efficient of thermal expansion (CTE) and increased dimensional stability.

“As miniaturisation of electronic devices continues, and functionality of those devices increase, the need for higher performing substrates has emerged,” explained Drew Walker, Vice President Marketing and Sales at AGY. “In response to this need, AGY has introduced S-3 HDI glass fibre for use in very thin high performance laminates.”

Containing a patent-pending glass composition, S-3 HDI glass fibre was developed with specific performance criteria in mind. “As laminates become thinner and circuit density increases, PCBs become more prone to warping,” said Walker.

“S-3 HDI glass fibre has a tensile modulus of 82 GPa (11.9 msi), which is 17% higher than the traditional E-Glass used in PCBs, and provides improved stiffness and excellent dimensional stability. In the case of IC package substrates, finer pitch circuitry and the elevated processing temperature of lead-free soldering have magnified the need for a closer match of the laminate CTE with that of the IC component. S-3 HDI fibre addresses this need with a CTE of 3.5 ppm/oC (1.9 ppm/°F), versus 5.4 ppm/oC (3.0 ppm/°F) for traditional E-Glass, yielding laminates with CTEs in the range of 10 ppm/oC (5.6 ppm/°F) versus E-Glass laminates at 15 ppm/oC (8.33 ppm/oF), depending on the choice of resin. This improves thermal stability and reduces stress at solder joints, resulting in higher reliability.”