Emerging PCB Laminate Trends
Laminate materials are used in PCB fabrication. As electronic systems designs continue to evolve exponentially, the trends in PCB laminate too are undergoing major changes. As per the emerging PCB laminate trends, substrate materials are being manufactured with fiberglass (FR4), polyimide, metal core laminates, PTFE, and ceramic materials.
Thermal management through Metal Core PCBs
Metal core PCB laminates are best for the thermal management of the high power electronic circuits used in automotive LED application, power converters in telecom industry and large scale urban development projects like street lights.
Nowadays, when the PCBs are integrated with power devices like motor drivers and controllers, power supplies, TV regulators, amplifiers and LED modules, it has become essential for sinking the thermal heat generated by these devices in a controlled way or else the PCB system will fail and the shelf life of the equipments will be reduced.
Traditional fiberglass (FR4) laminates have low thermal conductivity; therefore, metal core PCB laminates are used as an alternative. Metal cores PCBs dissipate heat approximately 9 times faster than fiberglass PCBs which keeps the heat generating electronic components cool, thereby prolonging the life of the board and enhancing performance.
High Quality FR4
PCB fabrication processes in terms of substrate evolution have undergone several improvements over the course of years. In PCB laminate industry, FR4 is typically used as a standard to compare other laminates. This material is preferable for it is low cost. Nowadays, FR4 laminates are available in the markets that have transmission rates up till 6 GBps – the signal depends upon the trace widths and the routing dimensions.
As the usage of lead-free solder was emphasized, FR4 also advanced in technology to support the cause. In order to curb the power costs, lead-free FR4 are now being utilized in high speed applications. The thermal-mechanical characteristics of FR$ is being improved by layering the boards with non-critical and hybrid PCB stack up. The Df rating of the FR4 has improved significantly.
Low Df and Dk PCB Laminates
PCB laminates suffer from conduction and dielectric losses. These laminates have Df ratings that are below 0.005. The Dk ratings should not be more than 3.7. Commonly, PTFE materials and recently even ceramic material (Rodgers 400 series) are a popular choice for low loss high speed PCB laminate. These laminates are used by complex high-density interconnect (HDI) PCBs.
Polyimide Laminate
Polyimide resins are used to manufacture the PCB substrate that is expected to be used in high temperature applications and process (up to 3000C). Alongside exceptional thermal stability, the polyimide substrate also makes up a better base for surface mounted PCB electronic components in flexible PCBs as compared to hard boards.
The thermal expansion coefficient is low and the high glass transition temperature combined with the low shrinkage of polyimide films reduces the stress at the interface with other PCB components at the time of construction. Additionally, polyimide laminates also offer high resistance to chemicals. In printed electronic technology, polyimide is estimable for being lightweight and possessing superior electrical properties.