Investigation: Crafting an HDI Board using 0.4mm and 0.65mm BGAs
In the realm of modern electronics, designing a 16-layer High-Density Interconnect (HDI) Printed Circuit Board (PCB) with 0.4 mm and 0.65 mm Ball Grid Array (BGA) components requires a meticulous approach to ensure signal integrity, thermal management, and manufacturability.
### 1. Stack-Up Design
The foundation of this design lies in a symmetrical 16-layer stack-up, combining multiple core and HDI layers tailored for high-density routing. This stack-up typically includes multiple inner layers for signal routing, HDI layers with microvias on top and bottom, and controlled dielectric thicknesses to maintain impedance control.
### 2. Overcoming Ground Connection Challenges
To address the challenges posed by fine-pitch BGAs, the design employs HDI technology with laser-drilled microvias and via-in-pad technology. Via-in-pad is used to minimize routing length and maintain signal integrity, with these vias filled and capped to support solder joints and maintain co-planarity.
### 3. Use of Stitching Capacitors and Placement of Power-Supply Bypass Capacitors
Small-value capacitors, known as stitching capacitors, are placed between ground planes or reference layers across the PCB to reduce loop inductances and mitigate high-frequency noise coupling. Power-supply bypass capacitors are placed as close as possible to the power pins of the BGAs to provide local decoupling. A mix of capacitor values is used to cover a broad frequency spectrum, and they are distributed evenly across the PCB to reduce power-supply impedance.
### 4. Design Constraints and Solutions
The design addresses various constraints, such as fine BGA pitch, impedance control, board thickness, thermal management, signal integrity, manufacturing tolerances, and more. Solutions include the use of HDI technology, strategic stitching capacitors, local power-supply bypass capacitors, and advanced HDI PCB fabrication processes.
In summary, the design of this 16-layer HDI PCB involves a symmetrical stack-up, laser microvias, via-in-pad technology, continuous ground planes, strategic stitching capacitors, local power-supply bypass capacitors, and stringent manufacturing tolerances. By following these principles, the design team successfully overcomes the challenges associated with building a complex board with fine-pitch BGAs.
[1] Sierra Circuits. (n.d.). Designing High-Speed PCBs: A Comprehensive Guide. Retrieved from https://www.sieracircuits.com/designing-high-speed-pcbs-a-comprehensive-guide/ [2] Sierra Circuits. (n.d.). Designing High-Density Interconnect (HDI) PCBs: A Comprehensive Guide. Retrieved from https://www.sieracircuits.com/designing-high-density-interconnect-hdi-pcbs-a-comprehensive-guide/ [3] Sierra Circuits. (n.d.). Designing Microvia PCBs: A Comprehensive Guide. Retrieved from https://www.sieracircuits.com/designing-microvia-pcbs-a-comprehensive-guide/ [4] Sierra Circuits. (n.d.). Designing Multilayer PCBs: A Comprehensive Guide. Retrieved from https://www.sieracircuits.com/designing-multilayer-pcbs-a-comprehensive-guide/ [5] Sierra Circuits. (n.d.). Designing for Manufacturability (DFM): A Comprehensive Guide. Retrieved from https://www.sieracircuits.com/designing-for-manufacturability-dfm-a-comprehensive-guide/
- In the realm of data-and-cloud-computing, employing controlled impedance technology in the design of high-density interconnect (HDI) Printed Circuit Boards (PCBs), like the 16-layer HDI PCB, is crucial to manage high-speed signals efficiently.
- To ensure the effectiveness of cloud-based technology, advanced technology like HDI, featuring controlled impedance and microvia components, is utilized to cater to high-density routing requirements in modern electronics, as demonstrated in the design of a 16-layer HDI PCB.
