Mobile electronic devices such as smartphones and tablets require highly populated printed circuit boards (PCBs) to support their functionality and performance requirements in an increasingly competitive market space. Consumers demand faster processing, high resolutions, and longer battery life all in the palm of their hand.
To deliver advanced functionality and performance, board and semiconductor package designers must work together to tightly pack semiconductor devices on PCBs in the most efficient ways possible without causing EMI issues. Mobile electronic device OEMs have no tolerance for EMI issues since performance and reliability drive consumer demand in this market.
To eliminate potential EMI issues caused by densely populated PCBs, PCB and semiconductor designers are investigating novel new ways of shielding semiconductor devices and printed circuit boards. Traditional metal EMI shields are no longer an option, as they take up too much board space and therefore reduce the overall competitive functionality of the mobile electronic device.
One possible solution is an integrated EMI shield: a semiconductor device which has an electrically conductive layer applied over the top and sides of the semiconductor package, which grounds the device to the printed circuit board internally. Integrating the EMI shield into the semiconductor package this way has two main advantages: first, it saves PCB space by incorporating the EMI shield into the semiconductor device itself, reducing the overall size of the final product, and, secondly, it simplifies the board design and shortens product cycles.
PVD or conductive organic coating
The two most common ways to create an integrated EMI shield are applying a metallization layer using some form of physical vapor deposition (PVD) or spraying an electrically conductive coating directly on the semiconductor package. Both technologies provide effective EMI shields, reduce the PCB footprint of the semiconductor device, and simplify the PCB design. Using a PVD process to create an integrated EMI shield can be a high risk and costly option.
In contrast, Chomerics advanced conductive coatings can be applied to semiconductor devices with minimal capital equipment investment in a continuous high volume application process. By applying a conductive coating in a continuous high volume application process, semiconductor manufacturers can minimize their risk and achieve the lowest overall cost/integrated EMI shield. Also, organic conductive coatings are more flexible than typical metalized PVD coatings, resulting in fewer adhesion issues following environmental exposure.
Another method of resolving EMI issues in electronic mobile devices is by applying an organic absorber coating to the semiconductor package or PCB to absorb surplus electromagnetic waves. Chomerics’ absorber coatings are formulated to absorb electromagnetic waves at customer-specific frequencies, and because they are non-conductive - can be applied directly to PCBs already populated with semiconductor packages. These absorber coatings can be applied to the PCBs or sections of the PCBs to reduce unwanted EMI noise after board assembly.
Five main advantages of using absorber coatings to address EMI issues:
They are non-conductive and don’t need to be electrically grounded to the PCB, simplifying or eliminating masking.
The coatings can address EMI issues on the PCB, in-between tightly packed semiconductor devices.
They can be tuned to absorb EMI at customer-specific frequencies.
The coatings can be applied at the end of a product design cycle to solve EMI issues without having to go through another re-design cycle.
They can be applied in a continuous high volume manufacturing environment with minimal capital equipment investment, making them a low cost, low-risk solution for board or component level EMI issues.
The challenges of suppressing board level EMI are not going away. On the contrary, as consumers continue to demand more and more functionality from their mobile electronic devices, OEMs must continue to find novel approaches to solve these ever-growing board level EMI issues without impacting product design cycles and manufacturing costs.