Printed circuit boards (PCB) are of two types depending on their substrates - rigid printed circuit cards and flexible printed circuit boards.
Why flexible circuits are necessary?
PCBs yesterday were mostly rigid. In this modern era of mobile technology around the world is inching toward miniaturization, the need was felt for circuit boards were lightweight, flexible, thin, small, and had high density wiring. Flexible printed circuit cards were invented to meet these needs. These are printed circuit boards that can be wired in three dimensions and can be reshaped to fit available space.
What are flexible circuits?
A flexible PCB consists of a flexible board, wirings provided on the flexible board and connection pads to be conductive through wirings, which are provided on the edge of the flexible plate. A copper foil is laminated to a resin substrate layers and joined by adhesive or by the application of heat and pressure in an integral joint. There can be more than one conductive layer for the manufacture of circuits on both sides. There are insulating layers, adhesive layers, and encapsulate the layers between the conductive layers to ensure sufficient isolation. The plastic substrate of flexible printed circuit boards is formed of polyimide or similar thermoplastic material, such as polyetherimide.
The substrate is then coated with an adhesive and includes a cable having a plurality of electrically conductive lines embedded. The openings may be formed in one of the insulation layers for electrical connection to other electronic components. Electronic devices are connected to each other. In general, the front and rear surfaces of them are covered with insulating layers for preventing a wiring pattern to be conducted to another wiring pattern formed on another circuit board.
6 Step basic DIY for flexible printed circuits
1. Take polyimide thin sheets of copper are coated on both sides. Cut the sheet to the required size. Make sure the copper is not stained and the edges of the sheet are not unequal, which can damage the printer later.
2. Take a solid ink printer that prints in melted wax. Wax forms a layer on the copper that protects it later as etching.
3. Using Computer Aided Design (CAD) to draw a diagram of your circuit.
4. Use the printer to print this design on a sheet of polyimide. Printed areas will come as copper tracks. Use easily distinguishable dark colours, like black or magenta.
5. Soak the printed polyimide ferric chloride. We are now in the stage called etching, in which ferric chloride is a copper engraver. It can take up to half an hour to trace to dissolve copper and polyimide to appear.
6. The circuit is now ready for mounting. You can cut in smaller circuits if necessary or use it as is. Holes are drilled with lasers for mounting electronic components. The circuit is now ready for welding.
Flex PCBs are easy to make and versatile in use. However, sophisticated equipment requires high quality PCB stay together for long. The right material, right hole, and expertise make all the difference.
The information was shared on behalf of Global Connector Technology, is a leading supplier of standard and custom interconnect products.