Package Structure Intersecting Pattern Portions for Bonding Strength
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Solution Overview
Problem
Conventional package structures with redistribution layers face delamination and cracking due to stress concentration on small contact areas and thermal variations, especially with fine circuits less than 25 um in width.
Innovation Solution
The package structure incorporates a pattern portion and fixing portions that intersect with the circuits, along with a bending portion in some embodiments, to increase the contact area between the circuits and passivation layers, enhancing bonding strength and mitigating thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the circuit width is reduced to less than 25 um to meet increased electrical contact requirements, then the circuit density and electrical functionality are improved, but the bonding strength between circuits and passivation layers deteriorates due to stress concentration on small contact areas
Solution Approach 1:
The circuit is segmented into multiple portions along its length, with at least one pattern portion formed on the passivation layer that intersects with the circuit. This segmentation increases the contact area between the circuit and passivation layer, distributing stress more evenly and preventing delamination while maintaining fine circuit dimensions for high density.
Solution Approach 2:
The pattern portion is strategically placed at specific locations where the circuit intersects with the passivation layer, creating localized reinforcement zones. This local quality enhancement strengthens the bonding interface precisely where stress concentration occurs, without requiring overall circuit width increase, thus maintaining high circuit density elsewhere.
2Productivity
If the circuit width is reduced to less than 25 um to achieve fine circuit configuration, then the electrical functionality is improved, but the circuit reliability deteriorates due to cracking from thermal stresses during operation
Solution Approach 1:
The circuit is divided into multiple portions with pattern portions intersecting the passivation layer at strategic locations. This segmentation creates expansion joints that can accommodate thermal expansion and contraction, reducing stress concentration that leads to cracking during temperature variations while maintaining fine circuit dimensions for high density.
Solution Approach 2:
The pattern portion acts as a pre-formed stress relief structure that anticipates and cushions against thermal stresses before they cause damage. By incorporating this intersecting pattern during fabrication, the circuit is pre-equipped to handle thermal expansion and contraction, preventing cracking and improving reliability during operation.
3Ease of manufacture
If conventional fabrication processes are used for fine circuits, then the manufacturing process is simple, but the bonding strength between circuits and passivation layers is insufficient leading to delamination
Solution Approach 1:
The pattern portion is formed on the passivation layer before the circuit is deposited, using standard photolithography and etching processes. This preliminary action creates the stress-distributing structure in advance, allowing the circuit to be formed over it using conventional processes, thus maintaining fabrication simplicity while achieving enhanced bonding strength.
Solution Approach 2:
The pattern portion creates localized regions of enhanced bonding interface between the circuit and passivation layer. These local quality improvements are achieved through additional pattern formation steps that intersect with the circuit path, providing targeted stress relief and bonding enhancement without requiring complete process redesign.
Data Source
AI summary
A package structure is disclosed, which includes a substrate having a body, a plurality of conductive pads formed on the body and a surface passivation layer formed on the body and having a plurality of openings for exposing the conductive pads; a plurality of conductive vias formed in the openings of the surface passivation layer and electrically connected to the conductive pads; a plurality of circuits formed on the surface passivation layer and electrically connected to the conductive vias, wherein the circuits have a plurality of electrical contacts; at least a pattern portion formed on the surface passivation layer and intersecting with the circuits; and a second passivation layer formed on the surface passivation layer, the circuits and the pattern portion d having a plurality of openings for exposing portions of the electrical contacts of the circuits, thereby strengthening the bonding between the circuits and the passivation layers.