An overview of multi-layer rigid and flex PCB fabrication

PCB fabrication is an all-important process in the entire system of creating circuit boards. They are the main building blocks that make electronic and computer equipment work. In electronics manufacturing, the board layers are assembled with a particular surface pattern. Many companies offer PCB manufacturing services and supply PCBs to other companies. One such company is Illinois-based Imagineering, Inc., which has been in operation for 20 years. So far, more than 2,500 companies have trusted them with their PCB needs, among other related services.

PCB fabrication

PCBs are typically built on sheets that have copper surfaces, materials for flexible circuit and membrane switches, and rigid laminates to be used on the circuit board.These sheets are basically insulators, and are called substrates. Substrates are typically made from special polymers, Teflon and ceramics. Imagineering, Inc. offers multi-layer rigid and flex PCB fabrication. They also offer hard-to-procure substrates like Aluminum-core PCBs.

Flex circuits are PCBs that have, as the name suggests, flexibility.
This allows it to have three-dimensional configurations which can save up to 75% of space. If board thickness and space constraints are issues in the electrical connections, using flex circuits is the perfect solution. It also has the feature of vibration and shock resistance, which saves up on repair and replacement costs. It has all the features of a rigid PCB such as high density, reliability and repeatability, but with the added feature of the board conforming to a desired shape during its application. A multi-layer flex circuit contains three or more conductive layers.

These layers have flexible insulating layers in between each one. The connections between layers are done through plated-through holes. Flex PCB fabrication has a customized routing path that is repeatable. Even though it is quite thin, it is quite durable and its longevity has been proven in the market. Flex PCBs are commonly used in consumer electronic devices with tightly assembled electric connections, hard disk drives and desktop printers. They are also widely utilized in industries such as Communications, Industrial, Aerospace, Automotive, Medical, Military, and Transportation.

There are also PCBs that are called rigid-flex. Rigid-flex PCBs are a combination of rigid PCBs that are connected by integrated flex circuits. Flex circuits can be added with rigid areas to provide hard support for sensitive connectors and components. Multi-layer rigid-flex circuits have two or more conductive layers. These layers contain flexible or rigid insulation in between each one. Rigid-flex PCBs are ideally used for circuits where the components must be mounted on both sides of the board. The integration of resistant areas which are rigid and the resilient areas which are flexible combine the best of both worlds.

There is usually a smooth transition between rigid and flex surfaces on a PCB. There are important considerations in designing and fabricating a multi-layer rigid-flex PCB. These considerations are materials selection, the number of layers in the design, adhesion methods and control over dimensions.

During the manufacturing process, their PCBs pass through stringent quality standards tests, including 6x solder tests at temperatures of 288 degrees Celsius. This assures customers that their PCBs are of the highest quality and will work efficiently and reliably.

PCB-Fabrication

Imagineering, Inc. adheres to PCB fabrication standards. All PCB manufacturers are asked to follow the RoHS directive which prohibits the use of certain raw materials in products. RoHS stands for The Restriction of Hazardous Substances and it is a European-initiated directive that bans these hazardous and toxic substances from manufacturing processes:

lead, mercury, hexavalent chromium, cadmium, polybrominated biphenyls, and polybrominated biphenyl ethers. This stems from the issue that electronic equipment made with lead and other hazardous materials that are thrown in junkyards mixes and dissolves with rain water and go straight to the water table. When a community drinks contaminated water, it leads to a serious host of health problems, affecting the central nervous system, kidneys, reproductive, and circulatory systems.

Safe and hazard-free materials in manufacturing PCBs include Isola and Nanya products. Instead of using traditional solder materials such as tin and lead, PCB manufacturers are now using replacement such as copper, immersion tin, immersion silver, and immersion gold in gluing the electronic components together. Aside from the replacement materials listed above, Imagineering, Inc. also uses an organic solder preservative called ENTEK/OSP.