Shinya Kawai

Nano-Silica Composite Laminate

This paper introduces a newly-developed Nano-Silica Composite Laminate packaging technology that utilizes a nano-silica matrix composite material with outstanding properties. Nano-Silica Composite Laminate packaging technology enables us to create a thinner, downsized packaging that is less susceptible to warpage. In order to verify the advantageous properties of Nano-Silica Composite Laminate, we measured the degree of warpage by utilizing a dielectric test substrate that was composed of Nano-Silica Composite Laminate and resin films. The results obtained in this study demonstrated that the dielectric material created using Nano-Silica Composite Laminate allows us to avoid the resins undesirable tendency of allowing the coefficient of thermal expansion (CTE) to increase when the temperature rises beyond the glass transition temperature. The storage modulus of Nano-Silica Composite Laminate showed 30 GPa, which is more than five times higher than that of ordinary resin. Therefore, we were able to confirm that using Nano-Silica Composite Laminate contributes to decreasing warpage of the conventional substrate during the packaging process. Furthermore, we confirmed that the test substrate has the following extremely reliable properties: it can maintain both conductivity and dielectricity under the conditions of both a line/space width of 10/10μm and a via diameter of 30 μm. Consequently, through the test results it has been confirmed that Nano-Silica Composite Laminate is one of the most appropriate substrates available to strengthen the interconnection between a silicon chip and substrate, and to protect the large-scale integrated (LSI) circuits from breaking.

Development of LTCC Materials with High Mechanical Strength

We have developed LTCC materials suitable for substrates of RF modules used in mobile phone. LTCC can provide excellent solutions to requirements of RF modules, such as down-sizing, embedded elements and high performance. It is also important that LTCC material has high mechanical strength to reduce risk of fracture by mechanical impact. We have established a method of material design for high mechanical strength. There are two successive steps in the concept to achieve high mechanical strength. The first step is to improve mechanical strength by increasing the Youngs modulus, and the second step is either further improvement through the Youngs modulus or enhancement of the fracture energy. The developed material, so called high-strength LTCC, thus possesses mechanical strength of 400MPa, which is twice as strong as conventional material whose mechanical strength is approximately 200MPa in typical. As a result, high-strength LTCC shows an excellent mechanical reliability, against the drop impact test for example. The paper presents material design and properties of LTCC materials.