Conductive Bumps for Packaging Substrate Bonding
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Solution Overview
Problem
The existing packaging substrate fabrication methods face issues with low bonding strength between conductive elements and conductive pads due to small contact areas, leading to delamination and non-wetting problems, which affect product reliability.
Innovation Solution
A packaging substrate with conductive bumps formed on the conductive pads that protrude above the dielectric layer surface, increasing contact area and preventing delamination, and a method involving forming a dielectric layer, a first circuit layer, and conductive bumps on the carrier, which ensures effective electrical connection and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a planar contact surface is used between conductive elements and conductive pads, then the fabrication process is simple, but the contact area is small leading to low bonding strength and delamination
Solution Approach 1:
The patent transforms the contact interface from a two-dimensional planar surface to a three-dimensional protruding structure. Conductive bumps are formed on the conductive pads, extending vertically upward to create multi-surface contact areas. This dimensional change allows conductive elements to contact the bumps from multiple angles, significantly increasing the effective contact area and bonding strength while maintaining fabrication simplicity through standard electroplating processes.
2Manufacturing precision
If the first circuit layer is recessed into the dielectric layer to create a lower surface, then the conductive pads are exposed, but non-wetting occurs causing conductive elements to stick on the dielectric surface without electrical connection
Solution Approach 1:
The patent applies preliminary action by forming conductive bumps on the conductive pads before the soldering or bonding process. These pre-formed protruding structures serve as ready-made contact points that guide the conductive elements to the correct location and provide immediate mechanical interlocking. This preliminary structuring prevents the non-wetting problem by ensuring that conductive elements contact the conductive bumps rather than sticking to the dielectric surface, thereby guaranteeing effective electrical connection.
3Reliability
If conductive bumps are formed on conductive pads, then contact area increases and bonding strength improves, but the fabrication process becomes more complex
Solution Approach 1:
The patent employs self-service by utilizing the existing conductive pad structure and electroplating process to automatically form the conductive bumps. The electroplating process naturally deposits metal material that protrudes from the pad surface, creating the bump structure without requiring separate machining or forming operations. This self-forming mechanism increases contact area and bonding strength while avoiding significant additional fabrication complexity, as the bumps are created as an integral part of the existing manufacturing flow.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The conductive bumps enhance bonding strength and prevent delamination by increasing contact area and ensuring proper wetting, thereby improving product reliability and ensuring effective electrical connection.
Implementation Method 1
a first circuit layer 11 is formed on the conductive layer 100 by electroplating
Data Source
AI summary
A packaging substrate is disclosed, which includes: a dielectric layer; a circuit layer embedded in and exposed from a surface of the dielectric layer, wherein the circuit layer has a plurality of conductive pads; and a plurality of conductive bumps formed on the conductive pads and protruding above the surface of the dielectric layer. As such, when an electronic element is disposed on the conductive pads through a plurality of conductive elements, the conductive elements can come into contact with both top and side surfaces of the conductive bumps so as to increase the contact area between the conductive elements and the conductive pads, thereby strengthening the bonding between the conductive elements and the conductive pads and preventing delamination of the conductive elements from the conductive pads.