Silicon Die Package Form Factors and Board Land Pattern Tolerances
Precision land pattern design balances component manufacturing tolerances against board assembly capability to eliminate thermomechanical stress on silicon die output registers.
Microvia in Pad
Via Filling
Connection structures integrate small laser drilled holes directly into the surface mount pads of a circuit board. Utilizing microvia in pad technology eliminates the need for separate fan out traces and saves significant surface area. This configuration allows for higher component density and more direct routing of signals from fine pitch packages.
Thermal Management
Copper filled vias provide a direct path for heat to move from the component into the internal power and ground planes. This improves the cooling of power sensitive parts and prevents hot spots on the board. The number of vias and their placement are optimized for both electrical and thermal performance.
Reliability Concern
Repeated thermal cycling can cause stress at the interface between the via fill and the plated cap. If the materials have different coefficients of expansion, the cap might bulge or crack over time. Strict manufacturing controls are necessary to ensure the adhesion of the plating remains intact during the life of the product.
Surface Planarity
The hole must be filled with a conductive or non conductive epoxy and then plated over with copper to create a flat solderable surface. If the via is left open, solder paste will wick into the hole during reflow and cause a poor joint. Planarization ensures that the pad is level and ready for component placement.
The final copper thickness on the pad must meet the IPC class requirements.