Printed circuit boards which may also be called Printed wiring boards or Printed wiring cards are the fundamental blocks in advanced modern circuits and advanced modern electronics. A printed circuit board in its essence is a board or a card which provides ways and means i.e. physical and electrical of connecting the electronic components. A PCB is a rigid board made from laminate comprising of mostly glass epoxy base material with coating of copper on single or either side of it. The rigid board provides physical means for handling or mounting the electronic components of an integrated circuit on it while the copper coating allows the drawing of copper paths which acts as wires for the conduction of electricity between the components.
When the base material of the printed circuit board is taken into account, the PCBs can be classified into two type i.e. flexible circuit boards and rigid circuit boards. The rigid circuit boards are made of substrate material which can range from glass epoxy resin material to ceramic and Teflon material. In case of flexible Printed Circuit Boards or flexible circuits, the substrate material is mostly a thin film of Polyimide and Polyester. The thickness of the substrate material can be same for the two types of the printed circuit boards but the flexible properties are greatly different.
Depending upon the layers in a flexible printed circuit board, they can be divided in to four main types namely,
- Single layer Flex Circuit
- Double layer Flex circuit
- Multi layer Flex Circuit
- Rigid Flex Printed circuit board
Single Layer Flex Circuit
A single layer flex circuit is the simplest and among the fundamentally basic kind of printed circuit boards. They comprise of a flexible polyimide film or sheet laminated with a thin layer of copper or the conducting material of the printed circuit board. The copper layer in the designing and development of the PCB is then chemically etched to produce a circuit pattern as per the specific design requirements of the integrated circuitry. A polyimide overlay can be provided for insulation and environmental protection of the printed circuit board.
The single layer flex circuit board has multiple advantages. Some of the advantages are listed below,
• The flexible circuit boards provide higher density as compared to their competitive rigid single layer circuit boards
• The design capability and flexibility provided by the flex circuits is much higher as compared with the rigid circuits.
• The impedance control in flexible circuits is superior as compared with the rigid circuits.
• The size and weight of the flex circuits can be much lower as compared with the rigid circuit as the flex circuits significantly reduces the need to use the wiring
• The optimal operating temperature range provided by the flex PCB is much higher as compared with the rigid circuits.
Double Layer Flexible Circuits
A double sided flex circuit comprises of two conducting layers, with conducting layers on each side of the substrate layer of polyimide within the printed circuit board. In case of double layer printed circuit board the trace patterns as per the specific design requirements of the integrated circuit can be etched on both sides of the substrate film and connection can be made where desired with copper plated through-holes commonly known as via. The plated through holes or PTH connect the two layers of the double sided printed circuit board for the conduction of electricity and signals between them.
Some of the advantages of the double layer printed circuit boards are given below,
• The double sided printed circuit boards are more flexible as compared to the rigid circuits and hence they provide more opportunities for installation and design of the electronic devices.
• There is better heat dissipation facility in flexible double sided printed circuit boards due to greater surface to volume ratio.
• The flexible circuit boards provide higher density as compared to their competitive rigid double layer circuit boards
• The design capability and flexibility provided by the flex circuits is much higher as compared with the rigid circuits.
• The impedance control in flexible circuits is superior as compared with the rigid circuits.
• The size and weight of the flex circuits can be much lower as compared with the rigid circuit as the flex circuits significantly reduces the need to use the wiring
• The optimal operating temperature range provided by the flex PCB is much higher as compared with the rigid circuits.
Multi Layer Flexible Printed Circuit Boards
A multi layer flexible printed circuit board comprises of number of single-layer or double-layer printed circuit boards with complicated and high density interconnections and connection, protecting layers and SMT mounting technologies in a multi layer PCB design. The connection between different layers of the PCB is through via of all kinds as per the needs of the design. They make the used of micro-via for greater density applications and provide better construction and layout options for the designers. HDI technology uses thinner material while provides greater reliability as compared to ordinary flexible circuits.
Some of the advantages of the Multi layer Printed Circuit Boards are as follow,
• The flexible circuit boards provide higher density as compared to their competitive rigid double layer circuit boards
• The design capability and flexibility provided by the flex circuits is much higher as compared with the rigid circuits
• The impedance control in flexible circuits is superior as compared with the rigid circuits.
• The size and weight of the flex circuits can be much lower as compared with the rigid circuit as the flex circuits significantly reduces the need to use the wiring.
• It also eliminates the need to color code the wires and making them into bundle thus driving the volume production up while at the same time driving the cost of manufacture down.
• They provide replacement for wire harness by greatly reducing the use of wires and connectors. It is estimated that the use of flexible circuits reduces the size and cost of wiring required in a conventional circuit by 75% while retaining the efficiency of operation and reliability of the conventional circuits.
Synergise PCB Inc. provides solutions for your flexible circuit needs with long term performance for your devices. We adhere to international norms and standards of manufacturing and our products can compete in quality and reliability anywhere in the international arena.
