**1.1. Objective**

90 Dielectric Material

3087, 2009

[7] Hoble, D.A., Claudia Staşac - The analysis of the inductive heating process in cylindrical structures.- Revista de tehnologii neconvenţionale nr.2 ICNcT ., ISSN1454-

[8] Di Barba P., Forghani B., Louwther D.A. – Discrete value deseing optimisation of a

[9] Bitoleanu Alex., Mihai Dan, Popescu Mihaela, Constantin Calin – Convertoare statice şi

[10] S. Lupi – Modelling for research and industrial development in induction heating – 4th

[11] Fireţeanu V.,Monica Popa, T. Tudorache, Ecaterina Vladu – Numerical Analysis of Induction trought Heating Processes and Optimal Parameters Evaluation – Proc. 6th

multiple coil inductor for uniform surface heating. – HES-04 , Padua , Italy

structuri de comandă performante – Ed. Sitech 2000 Craiova

International Symposium EMF 2003 Aachen.

Int.Conf. on EM Processing of Material EPM 2003 Lyon, France.

To determine dielectric properties of paddy waste as a potential alternative material for conventional PCB laminate materials. Paddy waste residues, which already possess the characteristic of these conventional laminates, can be strengthened by fabricating it in a tightly-compacted, highly-dense package. These PCB laminates need to be insulated to avoid short circuit, and be physically rigid to mechanically provide stability for the placement of the copper. These properties will then enable a low-cost, sustainable, and renewable solution, with a comparable performance to PCB laminates available in the market.

## **1.2. Background history**

Perlis is the smallest state in Malaysia with agriculture as its main economic activity. Rich rice fields cover most part of the state, enabling easy access to paddy wastes for the fabrication of these particle boards. The raw materials used in this work are rice husk and rice straw, gathered after the harvest season. It is known that fibers with the smallest particle size exhibits the highest tensile strength and hardness [1], hence its increased usage and demand. Within the 2010-2011 period only, about 577 million tonnes of rice (*Oryzae Sativa*) was produced worldwide. Malaysia is one of the more than 80 countries contributing to this sum, with 100,000 tonnes produced annually. Relative to the large quantity of produced agricultural residues (rice husk and rice straw), only a minor portion is reserved as animal feed, while the rest are burnt openly, causing concerns of air pollution [2]. Various

© 2012 Hoon et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

#### 92 Dielectric Material

other suitable application for such residues are such as mat production, pedestrian bridge, microwave electronic design application, etc [3-4].

Alternatives for PCB Laminates: Dielectric Properties' Measurements at Microwave Frequencies 93

). The relative

(2)

When complex permittivity is drawn as a simple vector, the real and imaginary components

ta

" r '

r ε

1 Energy Lost per cycle Energy Store

(3)

d per c cl <sup>=</sup> *Q* y e

In some cases the term "quality factor or Q – factor" with respect to an electronic microwave

Agricultural residues have been subjected to increasing interest, study, and utilization for some decades. The increase in environmental concerns rationalizes, the reduction of polymers' usage, not only because of their non-biodegradability, but also due to energyintensive production. In other words, polymer production and processing requires large amounts of oil as raw material, which is notoriously not renewable. All these issues induce

Paddy residues such as rice husk and rice straw, shown in Figure 1, are materials of interest for a wide range of applications. Non-destructive dielectric properties' measurements are essential for proper understanding of their electrical behavior, ensuring that they could be effectively put into applications. The use of paddy residues is advantageous due to its high silica content and thick walled , providing a fire-resistant feature. For a typical paddy waste fiber, burning causes a layer of char to develop on the outer surface, insulating its inner

(a) (b)

ε n 

are 900 out of phase. The vector sum forms an angle, δ, with the real axis ( *<sup>r</sup>*

"loss" of a material is the ratio of the energy lost to the energy stored.

tan =D

Loss Tangent

material is used.

the need for alternatives.

**Figure 1.** Paddy residues (a) rice straw (b) rice husk

straw [6].

Dielectric properties of a material define the physical-chemical properties related to the storage and loss of energy contained in a material or substance. The knowledge of a material's dielectric property is necessary in determining its suitability for a specific application. This property, which includes complex permittivity and dissipation factor, is unique for every material type. These unique sets of electrical characteristics are dependent on electromagnetic properties of the materials. Measurement of dielectric properties involves measurement of the complex relative permittivity (εr) and complex relative permeability (μr). A complex relative permittivity (εr) consists of a real part and an imaginary part. The real part of the complex permittivity, also known as dielectric constant is a measure of the amount of energy from an external electrical field stored in the material. The imaginary part is zero for lossless materials and is also known as loss factor. It is a measure of the amount of energy loss from the material due to an external electric field. The term tangent loss (tan δ) represents the ratio of the imaginary part to the real part of the complex permittivity, and is also known as loss tangent, dissipation factor or loss factor. Accurate measurements of these properties enable scientists and engineers to incorporate the material for the suitable application, for more solid designs or to monitor a manufacturing process for improved quality control [5].
