In the face of space constraints in electronic products like handheld or wearable devices, designers actively seek various methods to shrink the size of PCBA boards. An effective strategy is to adopt multilayer PCB, which can accommodate more circuits in a smaller space to meet the demands of miniaturization. However, as the number of layers increases, the difficulty and cost of manufacturing also rise. Therefore, it is advisable to consider fine-pitch ball grid array technology, which enhances PCB surface utilization by reducing chip package size. FS Technology will introduce this technology and showcase our capabilities through real-life case studies.

What is Fine Pitch Ball Grid Array

As the integration of integrated circuit functions continues to increase, more pins are required to connect and coordinate operations, leading to an increasing issue of electrical short circuits on circuit boards. The introduction of Fine Pitch Ball Grid Array (FBGA) effectively addresses this problem. FBGA packages create pins on the bottom surface of the package in the form of small bumps or solder balls, facilitating chip cooling and improved electrical connections.
Key Features of FBGA:
  • High Integration: FBGA can accommodate more connection points, increasing design flexibility for more complex and high-performance chips and circuits.
  • Reduced Package Size: Compared with traditional BGA, the tighter pitch of FBGA makes the package more compact and improves the utilization of PCB surface area, making it ideal for compact designs.
  • Efficiency: Due to the more compact connection line design, shorter signal transmission distances reduce resistance and inductance, improving circuit efficiency.
  • Case Study of SHENZHEN Technology’s FBGA Implementation

  • Technology is a Chinese turnkey PCB assembly company, providing one-stop services from design to assembly. In a previous project, a customer required an upgrade to their design, necessitating the addition of a Toshiba flash card with a 0.5mm pitch on the circuit board. The original board featured a 16-layer structure, using through-hole connections to link circuits between different layers. However, the new component had very fine pins that did not meet the through-hole requirements. Therefore, an alternative pin-out method was required to redesign the PCB to meet the fine pitch requirement. To meet the customer’s needs, FS Technology’s engineering department provided three potential solutions and conducted evaluations: Option 1: Use microvias with a 10mil diameter and 5mil laser-drilled holes, positioned at the center of the BGA solder pads, placed between the first and second layers. This approach would alter the board’s stacking structure, increase manufacturing costs, and necessitate a redesign of the previously effective circuit routing. Option 2: Employ 3mil traces with 3mil spacing, with the external two rows of pins fanned out on the component side between the pins. This method would increase the manufacturing cost of the PCB because it demanded tighter spacing than the industry standard, potentially causing issues during assembly. Option 3: Utilize the “thru-routing” method. Colleagues in the engineering department identified that seven pins could not be fanned out through a through-hole, leading to this suggestion. We contacted Toshiba to confirm that some of these pins were not internally connected within the IC. Upon confirmation, we were able to fan these adjacent solder pads directly out through the through-hole without changing the existing stacking structure, reducing the manufacturing cost of the PCB and maintaining high-quality design.