Coreless Packaging Substrate Protruding Elements Bonding
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Solution Overview
Problem
Conventional coreless packaging substrates have a small contact area between conductive pads and bumps, leading to poor bonding and reduced product reliability due to planar contact surfaces.
Innovation Solution
The formation of protruding elements on the conductive pads, which provide larger contact surfaces, including upper and side surfaces, to enhance bonding with external conductive elements such as bumps, and a method involving multiple layers and processes to fabricate these substrates, including resist layers, conductive layers, and dielectric layers for electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the conductive pads are reduced in size to meet miniaturization requirements, then the substrate size is reduced, but the contact area between conductive pads and bumps is reduced, resulting in poor bonding and reduced reliability
Solution Approach 1:
The invention transforms the contact interface from a two-dimensional planar surface to a three-dimensional protruding structure. The protruding elements extend vertically from the conductive pad surface, creating multiple contact surfaces (top surface and lateral surfaces) that engage with the bump structure. This dimensional transition effectively increases the contact area without expanding the planar footprint of the conductive pad, thereby maintaining miniaturization while improving bonding reliability.
Solution Approach 2:
The protruding elements are designed with curved or rounded surfaces rather than sharp edges, creating a spheroidal contact interface. This curvature allows for better mechanical interlocking with the bump structure and distributes contact stresses more evenly across the interface, enhancing bonding strength and reliability while maintaining a compact form factor.
2Ease of manufacture
If planar contact surfaces are used between conductive pads and bumps, then the manufacturing process is simple, but the contact area is small, resulting in poor bonding
Solution Approach 1:
The protruding elements are formed on the conductive pad surfaces before the bump attachment process. This preliminary structuring of the contact surface ensures that when bumps are subsequently attached, they engage with the pre-formed three-dimensional contact surfaces, achieving enhanced bonding strength without requiring complex post-attachment processing or additional manufacturing steps.
Data Source
AI summary
A coreless packaging substrate is provided, which includes: a dielectric layer having opposite first and second surfaces; a first circuit layer embedded in the dielectric layer and exposed from the first surface of the dielectric layer, wherein the first circuit layer has a plurality of first conductive pads; a plurality of protruding elements formed on the first conductive pads, respectively, wherein each of the protruding elements has contact surfaces to be encapsulated by an external conductive element; a second circuit layer formed on the second surface of the dielectric layer; and a plurality of conductive vias formed in the dielectric layer for electrically connecting the first circuit layer and the second circuit layer. The present invention strengthens the bonding between the first conductive pads and the conductive elements due to a large contact area between the protruding elements and the conductive elements.