Semiconductor Substrate Metal Deposition Embedding
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Solution Overview
Problem
Conventional semiconductor chip packages face issues with over etching during metal thin deposition, leading to unsupported metal layers that collapse, peel, or break during electrical testing or wire bonding due to dimensional limitations and profile constraints.
Innovation Solution
A substrate with a dielectric layer, conductive circuits, and bonding pads, where a metal thin deposition layer protrudes over the conductive circuits and bonding pads, with the protruding portion embedded in a solder mask to prevent collapse and breakage during testing or bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the metal thin deposition layer is formed by over etching to extend beyond bonding pads, then the coverage area is improved, but the structural stability deteriorates causing collapse and breakage
Solution Approach 1:
The solder mask serves as an intermediary substance that fills the space beneath the protruding metal thin deposition layer. This mediator provides mechanical support to the unsupported portions of the metal layer, preventing collapse and breakage while allowing the layer to extend beyond the bonding pads for improved coverage area.
2Area of stationary object
If the metal thin deposition layer protrudes over bonding pads to increase coverage, then the electrical connection area is improved, but the reliability deteriorates due to collapse and breakage during testing and bonding
Solution Approach 1:
The solder mask is applied beforehand to cover the substrate surface, creating a protective cushioning layer before the metal thin deposition is formed. This pre-existing support structure prevents the metal layer from collapsing under subsequent mechanical stresses during electrical testing and wire bonding operations.
3Object-affected harmful factors
If the solder mask covers the bonding pads to protect them, then the protection function is improved, but the electrical connectivity worsens due to obstruction
Solution Approach 1:
The solder mask is applied with local quality differentiation: it covers and protects most areas of the substrate including the bonding pads, but deliberately leaves specific regions exposed to maintain electrical connectivity. This selective coverage allows the solder mask to provide mechanical protection where needed while preserving electrical pathways where required.
Data Source
AI summary
A substrate for packaging a semiconductor chip includes a dielectric layer, a plurality of conductive circuits and bonding pads formed on the dielectric layer, a metal thin deposition layer formed on the conductive circuits and the bonding pads, and a solder mask formed on the dielectric layer and the conductive circuits. The first ends of the bonding pads extend from the conductive circuits. The metal thin deposition layer has at least a portion to protrude out of the conductive circuits and the bonding pads such that the protruding portion of the metal thin position layer is not supported by the conductive circuits or the bonding pads. The bonding pads are exposed form the solder mask except that the second end of each bonding pad is covered by the solder by the solder mask in the manner that the protruding portion of the metal thin deposition layer is embedded in the solder mask.