Wiring Substrate Pad Geometry for Dense, Oxidation-Resistant Bonding
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Solution Overview
Problem
Existing display technologies face challenges in manufacturing wiring substrates for Mini LED and Micro LED display apparatuses, particularly in ensuring reliable electrical connections and preventing oxidation, which affects the reliability and efficiency of the display panels.
Innovation Solution
A wiring substrate design featuring a conductive layer with pad groups and a protective layer, where the conductive pads have specific dimensions and orientations, and an oxidation prevention layer to enhance soldering reliability and prevent abnormal growth phenomena, along with a method of manufacturing that includes forming conductive layers and protective layers with precise openings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conductive pad size is increased to improve soldering reliability, then the electrical connection reliability is improved, but the area occupied by each pad increases reducing the number of pads that can be accommodated
Solution Approach 1:
The patent applies different dimensions to conductive pads in different directions: the first dimension (length) is set to 1.5-5 times the distance between adjacent pads, while the second dimension (width) is set to 0.5-2 times the distance between adjacent pads. This anisotropic design optimizes soldering reliability along the primary connection direction while minimizing area consumption in the perpendicular direction, allowing more pads to be accommodated on the substrate.
2Productivity
If the distance between conductive pads is reduced to increase pad density, then the number of pads per unit area increases, but the risk of short circuits and oxidation between adjacent pads increases
Solution Approach 1:
The patent establishes specific parameter ranges for pad dimensions relative to spacing: the first dimension is 1.5-5 times the spacing, and the second dimension is 0.5-2 times the spacing. These parameter relationships ensure that pads are compact enough to achieve high density while maintaining sufficient isolation to prevent short circuits and oxidation, thus balancing productivity and reliability.
3Reliability
If the conductive layer is exposed more extensively to ensure proper soldering, then the soldering reliability is improved, but the oxidation of the conductive layer increases
Solution Approach 1:
The patent applies an oxidation prevention layer on the conductive layer before the soldering process. This preliminary protective action prevents oxidation of the conductive layer during manufacturing and operation, while the conductive pads are designed with appropriate dimensions to ensure proper soldering coverage. The prevention layer remains intact in non-soldering areas while allowing controlled exposure where needed.
Data Source
AI summary
A wiring substrate includes a substrate, at least one conductive layer(s) located on a side of the substrate, and a protective layer located on a side of the at least one conductive layer. A conductive layer includes a plurality of pad groups, and a pad group includes a plurality of conductive pads. The protective layer includes a plurality of openings; a portion of the conductive layer exposed by an opening is a conductive pad. A maximum dimension of the conductive pad in a direction parallel to the substrate is greater than or equal to 1.5 times a minimum distance between an edge of the conductive pad and an edge of the conductive layer, and less than or equal to 30 times the minimum distance between the edge of the conductive pad and the edge of the conductive layer.