Display Panel Chip Bumps With Composite Contacts for Bent Carriers
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Solution Overview
Problem
Conventional display panel packages experience bonding issues and shear stress-related failures at bent portions due to inadequate bonding strength between the chip and the carrier, leading to cracks, breaks, and open circuits.
Innovation Solution
The introduction of composite contacts with a base and a bonding layer on the bumps, forming a nonplanar surface, which increases the bonding area between the bumps and second pads, enhancing the bonding strength and resistance to shear stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a chip is mounted on a bent portion of a carrier using conventional bumps, then the display panel can be bent to conform to curve requirements, but shear stress causes cracks, breaks, or peeling at the bumps or intermetallic interface
Solution Approach 1:
The patent applies composite contacts consisting of a base and a bonding layer with different material properties. The base provides mechanical strength and stress resistance, while the bonding layer provides strong adhesion to both the chip pad and carrier pad. This composite structure resolves the contradiction by combining materials with complementary properties to simultaneously achieve bendability and bonding reliability.
Solution Approach 2:
The patent transitions from planar (2D) contacts to three-dimensional (3D) nonplanar contacts with bumps having composite structures. This dimensional change increases the bonding area and creates a gradient structure that better distributes shear stress during bending, thereby improving both adaptability to bending and bonding strength simultaneously.
2Device complexity
If conventional planar bumps are used for mounting chips on bent portions, then the structure remains simple, but the bonding area is insufficient leading to shear stress failures
Solution Approach 1:
The patent employs nonplanar contacts with bumped (curved) surfaces instead of flat contacts. The spherical/curved geometry increases the contact area between the bump and pads, distributing shear stress more effectively. This curvature-based approach enhances bonding strength without requiring complex multi-layer structures, maintaining relative structural simplicity.
Solution Approach 2:
The invention moves from two-dimensional planar contacts to three-dimensional nonplanar contacts with vertical height and curved surfaces. This dimensional enhancement naturally increases bonding area and creates stress distribution pathways that improve strength while adding only moderate structural complexity.
Data Source
AI summary
A display panel package includes a carrier, light-emitting elements and a chip, the light-emitting elements are mounted on the carrier, and the chip is mounted on a portion to be bent of the carrier. The chip includes bumps each having at least one composite contact. The composite contact includes a bonding layer and a base which is covered by the bonding layer to form a nonplanar surface on each of the bumps. The bonding layer located on the nonplanar surface is bonded to a pad of the carrier to increase bonding area of the bump and the pad and improve bonding strength between the carrier and the chip.