Wiring Substrate Dummy Posts for Uniform Underfill Fillet

The patent applies local quality by varying the height of posts at different locations along the periphery. Specifically, posts at corner positions are set at a first height, posts at central portions of sides are set at a second height (lower than the first), and posts at other peripheral portions are set at intermediate heights. This localized variation in post height controls the underfill material drainage pattern to achieve uniform fillet formation around the relay board while maintaining manufacturing feasibility through a systematic height distribution pattern.

The patent introduces posts as intermediary structures that mediate between the main board and relay board during the joining process. These posts, with specifically designed varying heights, act as control elements that guide the underfill material drainage. The posts prevent uncontrolled spreading of the underfill material while still allowing it to flow to form fillets, thereby achieving uniform fillet shapes that provide adequate mounting area and flexibility for placing parts near the relay board without requiring complex joining processes.