Fiberglass news from “DD Fiberglass“, Apr 10th, 2009.

AGY has introduced L-Glass, a low-loss glass fibre yarn for printed wiring board (PWB) applications.

L-glass fiber introduction:

In response to the rapid development of high-speed digital electronic systems, AGY, a leading global producer of glass fiber yarns and high-strength glass fiber reinforcements, has introduced L-Glass™, a new low-loss glass fiber yarn for printed wiring board (PWB) applications; as unveiled on March 24, 2009. The low dielectric constant (Dk) and low dissipation factor (Df) properties of L-Glass fiber are ideally suited for designs requiring increased signal speeds and better signal integrity than traditional E-Glass/epoxy substrate materials.

Low-loss laminates for high-speed applications have traditionally been produced in one of two ways. In one method, a higher performing epoxy resin system is used in conjunction with E-Glass. This approach limits the achievable Dk and Df properties.

The second method combines very low Dk/Df resins, such as PTFE, with ceramic filler and a much lower E-Glass content. While these systems can achieve much lower Df/Dk properties, they suffer from high material and processing costs. The low glass loading also reduces the dimensional stability of the laminate. The use of L-Glass fiber overcomes these limitations by allowing epoxy resin systems to achieve much lower Dk/Df properties, and the PTFE-based systems to use a higher glass loading.

At 10 GHz L-Glass fiber has a dielectric constant of 4.86 and a dissipation factor of 0.0050 whereas E-Glass has a dielectric constant of 6.81 and a dissipation factor of 0.0060 at 10 GHz. The coefficient of thermal expansion (CTE) of L-Glass fiber is 3.9 ppm/°C compared to 5.4 ppm/°C for E-Glass. This makes L-Glass fiber an attractive material for use in IC packaging, where CTE mismatches with silicon are magnified due to the thermal environment and can cause defects.

L-glass fiber properties:

• Low dielectric constant (Dk)
• Low dissipation factor (Df)

L-glass fiber applications:

Substrate materials that provide low dielectric constant and low dissipation factor properties have become an essential element of high-speed digital systems such as mobile communication base stations, high-end routers and servers, and high speed storage networks. As these systems move to higher processing speeds, substrates with low-loss properties are needed to ensure the speed and integrity of the signals.

L-Glass fiber is a cost-effective alternative to current systems,The low- loss properties make it ideal for applications operating at the highest signal speeds and provide designers a compelling alternative to traditional materials.

L-glass fiber specifications:

AGY’s L-Glass fibers will be available in a variety of yarn counts, that will allow production of low-loss fabrics analogous to styles 106, 1080, 2113/2313, and 2116.

Additional yarn counts can be produced as needed to meet market demands.