- 1. Higher I/O (input/output) density. As the drive to reduce board size continues, the need for greater I/O density intensifies. The fine-pitch µBGA package offers several times the amount of I/Os per square inch of PCB space than the widely used BGA.
- 2. Mechanically robust design. The µBGA can be handled without concern for bending and misaligning the leads. This reduces component packaging costs and pre-assembly defect rates of components.
- 3. More stringent placement tolerances. Standard BGAs typically offer a much larger pitch between terminals, making them more forgiving in terms of placement accuracy. The µBGA and land grid array (LGA) with their smaller ball size and lower pitch require more accurate placement. Typically, a machine with a placement accuracy of 1mil is required. Likewise, the use of lead-free solders presents additional challenges, including decreased occurrences of self-centering during reflow and the inability to rely on the surface tension of the solder self-centering the device as in the past with standard, leaded BGAs.
- 4. Direct thermal path. In terms of heat dissipation from component to PCB, the LGA’s center ground pad provides a direct path for heat to dissipate into the board. This reduces the thermal resistance of the interconnections, thus minimizing the likelihood of damage to the chip and internal wire bonds.
- 5. Ease of stencil printing. The LGA makes the stencil printing process a requirement for rework since these components are supplied without solder. An LGA stencil plate must be designed to meet the requirements of the pattern and be fitted to the rework machine.
- 1. Reflow (for removal)
- 2. Site preparation
- 3. Solder paste or flux deposition
- 4. Placement
- 5. Reflow
