Wiring Substrate Stepped Cavity Insulation Adhesion
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Solution Overview
Problem
The existing wiring substrates face issues with unsatisfactory adhesion between interlayer insulation layers and the insulation layer filling the cavity, leading to separation when the substrate warps, affecting the reliability of electronic components like chip capacitors.
Innovation Solution
A coreless wiring substrate design with a stepped inner wall surface in the second insulation layer, creating a cavity with a recess wider than the opening, enhances adhesion by anchoring the filling insulation layer, ensuring better insulation and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cavity is formed in the interlayer insulation layer to mount electronic components, then the electronic component can be integrated into the wiring substrate, but the adhesion between the interlayer insulation layer and the filling insulation layer becomes insufficient, causing separation when the substrate warps
Solution Approach 1:
The patent applies curvature by forming a recess with a curved bottom surface in the interlayer insulation layer. This curved recess structure improves adhesion between the interlayer insulation layer and the filling insulation layer, preventing separation when the substrate warps, while still accommodating electronic components effectively
2Reliability
If the cavity is filled with insulation layer to cover the electronic component, then the electronic component is protected and insulated, but the filling insulation layer separates from the interlayer insulation layer due to insufficient adhesion
Solution Approach 1:
The curved bottom surface of the recess enhances the bonding interface between the interlayer insulation layer and the filling insulation layer. This curvature increases the contact area and mechanical interlocking, ensuring the filling insulation layer remains firmly attached while providing adequate insulation and protection for the mounted electronic component
3Adaptability or versatility
If the wiring substrate undergoes warping during manufacturing or operation, then the substrate can accommodate manufacturing tolerances and thermal expansion, but the insulation layer separates from the wiring substrate due to poor adhesion
Solution Approach 1:
The curved recess structure creates a mechanical interlocking effect that maintains strong adhesion between insulation layers even when the substrate warps. The curved geometry allows the structure to accommodate warping stresses while preventing delamination, ensuring the insulation layer remains firmly attached throughout the substrate's operational life
Data Source
AI summary
A wiring substrate includes a first wiring substrate, a first insulation layer covering the first wiring layer, a second insulation layer stacked on the first insulation layer, and a cavity extending through the second insulation layer and exposing a portion of the upper surface of the first insulation layer. The cavity includes an opening, which is defined by an upper portion of a stepped inner wall surface of the second insulation layer, and a recess, which is defined by a lower portion of the stepped inner wall surface that contacts the upper surface of the first insulation layer. The recess is wider than the opening. An electronic component is mounted on the upper surface of the first insulation layer. The opening and the recess are filled with a third insulation layer that covers the electronic component and the second insulation layer.