The global electronics market is heavily influenced by various factors such as Artificial Intelligence (AI), automation and digitalisation. The fast-paced development of materials and processing is only necessary to support the huge demand for reliable electronics. Not all devices should be high-speed, but also compact and lightweight, requiring advanced packaging technologies.
The scaling down in size of semiconductor chips in the electronics industry triggered the development of substrate interconnection that will support product requirements. Printed Circuit Boards or PCBs are the substrates that hold the components to provide physical, electrical and structural support for these semiconductor packages. In this artqicle, we will get to know more about one type of printed circuit board, which is the IC Substrate PCB. Furthermore, we will discuss its structure, materials, benefits and applications.
What is an IC Substrate PCB?
An IC Substrate PCB is a type of printed circuit board particularly intended for mounting ICs or Integrated Circuits. It provides interconnection between the semiconductor chip and the conventional printed circuit board, providing both electrical routing and structural support on the IC component. This allows sophisticated integration as a significant interface between tiny packages and macroscopic printed circuit boards.
IC substrate PCBs have higher density available for routing compared with traditional printed circuit boards. These PCBs have micro vias multi-drilled for fine trace routing. Multiple layers within the IC substrate circuit board are dedicated to high-speed and high-frequency applications. Its manufacturing process involves core layer preparation through lamination processes, drilling, plating and surface finish processes.
What are the Different Types of IC Substrate PCBs?
Below are the different classifications of IC substrate PCBs according to the type of semiconductor packaging.
- Ball Grid Array (BGA). This type of IC substrate PCB connects semiconductor packages with a grid of solder balls that are the input-output interconnects of the chip. The solder balls allow high density and superior thermal performance.
- Flip Chip (FC) Package. Flip chip Package IC substrate consists of an IC that is oriented upside down, which is connected through wire bonding or ball grids. FC substrates are also favourable for high I/O density with good electrical performance.
- Chip Scale Package (CSP). Chip-scale Package IC substrates are highly miniaturised with a surface mount IC component that is as small as the semiconductor chip. It enables small form factors due to a small mounting area.
How is the IC Substrate PCB Manufactured?
To deepen the understanding of IC substrate PCB, we will explain the manufacturing process of IC substrate circuit board:
- Core Material Preparation: The core material, usually FR-4, is layered with conductive copper. Subsequent lamination processes are performed to combine the stacks together. The core material has a very thin profile; thus, lamination processes must be controlled.
- Via Drilling: Vias are drilled through laser or mechanical means to add conductive channels across layers. Micro-vias are often laser-drilled to enable high-density interconnects.
- Plating and Etching: The drilled vias are plated with copper to make vertical structures conductive. Etching, through photolithography, is done to form the desired circuit pattern. Etching is done using either chemical or plasma to remove the unnecessary copper.
- Solder Masking: To protect the circuit from solder shorting, a solder mask is applied on the PCB surface. Aside from isolating the circuit, it also shields the IC substrate PCB from getting contaminated or oxidised.
- Surface Finish: The solderability of copper pads is further enhanced using a metallic surface finish. This final surface coating is also needed to protect the reactive copper from oxidising.
- Inspection and Testing: Inspection and testing are done to check if the IC substrate PCBs are free from physical defects. The final PCBs must meet the specifications in terms of electrical, functional and visual standards.
What are the Benefits of IC Substrate PCB?
We will expand our understanding of the vast benefits of using IC substrate PCB. Below are its major benefits:
- Miniaturization. For applications where space and weight are both constraints, IC substrate PCBs bridge the gap for higher functionality and optimal form factor. Laser drilling is typically done to form micro-vias, which are necessary for high-density applications. Chip-scale packaging and Ball grid array packages are used for high-density interconnects to lessen the physical soldering footprint.
- Good Thermal Management. Proper heat dissipation is a critical parameter in IC substrate PCB design. Thermal vias and heat sinks are incorporated into the PCB design to channel the heat away from significant components. Proper thermal management assists in maintaining the electrical and signal integrity of the circuit. This technique is even more suitable for high power densities to enable the PCB to work at an optimum level at high power and temperature ranges.
- High-Density Interconnect Reliability. High-performance resin materials are used to build the stack-up of IC substrate PCB, ensuring good impedance across layers and long-term reliability. Thermal cycling is being conducted as well as stress tests against humidity and moisture to evaluate the IC substrate PCB’s reliability.
- Superior Electrical Performance. IC substrate circuit boards are dependable solutions, especially for high-speed and frequency applications. Signal losses are minimised through careful design by controlling impedance correctly. Laminates with low dissipation factors and dielectric constant are utilised to keep signal integrity.
What are the Applications of IC Substrate PCB?
Year-on-year growth of the semiconductors and electronics market is still expected to be observed due to recent trends and important drivers for higher computing power and better system integration.
- Consumer Electronics. The most familiar application of IC substrate PCBs is consumer electronics. Mobile phones and computers consist of miniaturised IC substrates such as System-in-Package (SiPs) and Package on Package (PoP). These technologies are characterised by high-density layers and embedded passives.
- Automotive and Mobility. Automotive markets have a strong demand for IC substrate PCBs with the requirement for 5G and high-performance computing (HPC). These PCBs are qualified for high reliability through thermal cycling tests.
- Medical. Devices used as implants, such as pacemakers and neurostimulators, have sensors and interposer boards that must be qualified for life-critical applications. A few of the important features of medical IC substrate PCBs include high reliability, ultra-thin laminates, and biocompatibility of surface finishes.
- Industrial. Industrial equipment using intelligent sensors has sophisticated substrate PCB interconnects that can tolerate long service cycles and withstand harsh environments. Vision systems in industrial devices utilise electronics with an IC substrate PCB suited for long-term reliability.
Conclusion
IC substrate PCB plays a crucial role towards higher integration and better performance electronics. Raw material suppliers, IC substrate circuit board manufacturers and customers must work together to understand critical requirements in achieving a fully functional product. In the long run, IC substrate PCBs will still be a major technology in the development of advanced devices in many applications.
